Low Power, Three Electrode
Electrocardiogram (ECG) Analog Front End
Data Sheet
ADAS1000-3/ADAS1000-4
FEATURES
Biopotential signals in; digitized signals out
3 acquisition (ECG) channels and one driven lead
Can be ganged for 8 electrode + RLD using master
ADAS1000 or ADAS1000-1
AC and DC lead-off detection
Internal pace detection algorithm on 3 leads
Support for user’s own pace
Thoracic impedance measurement (internal/external path)
Selectable reference lead
Scalable noise vs. power control, power-down modes
Low power operation from
11 mW (1 lead), 15 mW (3 leads)
Lead or electrode data available
Supports AAMI EC11:1991/(R)2001/(R)2007, AAMI EC38
R2007, EC13:2002/(R)2007, IEC60601-1 ed. 3.0 b:2005,
IEC60601-2-25 ed. 2.0 :2011, IEC60601-2-27 ed. 2.0
b:2005, IEC60601-2-51 ed. 1.0 b: 2005
Fast overload recovery
Low or high speed data output rates
Serial interface SPI-/QSPI™-/DSP-compatible
56-lead LFCSP package (9 mm × 9 mm)
64-lead LQFP package (10 mm × 10 mm body size)
APPLICATIONS
ECG: monitor and diagnostic
Bedside patient monitoring, portable telemetry, Holter,
AED, cardiac defibrillators, ambulatory monitors, pace
maker programmer, patient transport, stress testing
GENERAL DESCRIPTION
The ADAS1000-3/ADAS1000-4 measure electro cardiac (ECG)
signals, thoracic impedance, pacing artifacts, and lead-on/off
status and output this information in the form of a data frame
supplying either lead/vector or electrode data at programmable
data rates. Its low power and small size make it suitable for
portable, battery-powered applications. The high performance
also makes it suitable for higher end diagnostic machines.
The ADAS1000-4 is a full-featured, 3-channel ECG including
respiration and pace detection, while the ADAS1000-3 offers
only ECG channels with no respiration or pace features.
The ADAS1000-3/ADAS1000-4 are designed to simplify
the task of acquiring and ensuring quality ECG signals.
They provide a low power, small data acquisition system for
biopotential applications. Auxiliary features that aid in better
quality ECG signal acquisition include: multichannel averaged
driven lead, selectable reference drive, fast overload recovery,
flexible respiration circuitry returning magnitude and phase
information, internal pace detection algorithm operating
on three leads, and the option of ac or dc lead-off detection.
Several digital output options ensure flexibility when monitor-
ing and analyzing signals. Value-added cardiac post processing
is executed externally on a DSP, microprocessor, or FPGA.
Because ECG systems span different applications, the
ADAS1000-3/ADAS1000-4 feature a power/noise scaling
architecture where the noise can be reduced at the expense
of increasing power consumption. Signal acquisition channels
may be shut down to save power. Data rates can be reduced to
save power.
To ease manufacturing tests and development as well as offer
holistic power-up testing, the ADAS1000-3/ADAS1000-4
offer a suite of features, such as dc and ac test excitation via
the calibration DAC and CRC redundancy testing in addition
to readback of all relevant register address space.
The input structure is a differential amplifier input thereby
allowing users a variety of configuration options to best suit
their application.
The ADAS1000-3/ADAS1000-4 are available in two package
options: either a 56-lead LFCSP or a 64-lead LQFP package;
they are specified over −40°C to +85°C temperature range.
Rev. B Document Feedback
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ADAS1000-3/ADAS1000-4 Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Revision History ............................................................................... 3
Functional Block Diagram .............................................................. 4
Specifications ..................................................................................... 5
Noise Performance ..................................................................... 10
Timing Characteristics .............................................................. 11
Absolute Maximum Ratings .......................................................... 14
Thermal Resistance .................................................................... 14
ESD Caution ................................................................................ 14
Pin Configurations and Function Descriptions ......................... 15
Typical Performance Characteristics ........................................... 18
Applications Information .............................................................. 25
Overview ...................................................................................... 25
ECG Inputs—Electrodes/Leads ................................................ 27
ECG Channel .............................................................................. 28
Electrode/Lead Formation and Input Stage Configuration .. 29
Defibrillator Protection ............................................................. 33
ESIS Filtering............................................................................... 33
ECG Path Input Multiplexing ................................................... 33
Common-Mode Selection and Averaging .............................. 34
Wilson Central Terminal (WCT) ............................................. 35
Right Leg Drive/Reference Drive ............................................. 35
Calibration DAC ......................................................................... 36
Gain Calibration ......................................................................... 36
Lead-Off Detection .................................................................... 36
Shield Driver ............................................................................... 37
Respiration (ADAS1000-4 Model Only) ................................. 37
Evaluating Respiration Performance ....................................... 41
Pacing Artifact Detection Function (ADAS1000-4 Only).... 41
Biventricular Pacers ................................................................... 45
Pace Detection Measurements ................................................. 45
Evaluating Pace Detection Performance ................................. 45
Pace Width .................................................................................. 45
Pace Latency ................................................................................ 45
Pace Detection via Secondary Serial Interface ....................... 45
Filtering ....................................................................................... 46
Voltage Reference ....................................................................... 47
Gang Mode Operation ............................................................... 47
Interfacing in Gang Mode ......................................................... 50
Serial Interfaces ............................................................................... 51
Standard Serial Interface ........................................................... 51
Secondary Serial Interface ......................................................... 55
RESET .......................................................................................... 55
PD Function ................................................................................ 55
SPI Output Frame Structure (ECG and Status Data) ................ 56
SPI Register Definitions and Memory Map ................................ 57
Control Registers Details ............................................................... 58
Interface Examples ..................................................................... 74
Software Flowchart .................................................................... 77
Power Supply, Grounding, and Decoupling Strategy ............ 78
AVDD .......................................................................................... 78
ADCVDD and DVDD Supplies ............................................... 78
Unused Pins/Paths ..................................................................... 78
Layout Recommendations ........................................................ 78
Outline Dimensions ....................................................................... 79
Ordering Guide .......................................................................... 80
Rev. B | Page 2 of 80
Data Sheet ADAS1000-3/ADAS1000-4
REVISION HISTORY
1/15—Rev. A to Rev. B
Changed Frequency Range from 2.031 kHz (Typ) to 2.039 kHz
(Typ); Table 2 ..................................................................................... 7
Changes to Endnote 3; Table 3 and Changes to Table 4 ............. 10
Changes to Figure 16 ...................................................................... 18
Changes to Figure 39 and Figure 40 ............................................. 22
Changes to ECG Channel Section ................................................ 28
Changes to Digital Lead Mode and Calculation Section and
Electrode Mode: Common Electrode A and Common
Electrode B Configuration Section; Added Figure 55;
Renumbered Sequentially .............................................................. 29
Deleted Table 11; Renumbered Sequentially ............................... 29
Added Figure 56 and Figure 57 ..................................................... 30
Added Figure 58 and Figure 59 ..................................................... 31
Added Figure 60 .............................................................................. 32
Changes to Figure 61, Figure 62, and Figure 63 .......................... 33
Changes to Lead-Off Detection Section ...................................... 36
Added Figure 66 and Changes to Respiration (ADAS1000-4
Model Only) Section ....................................................................... 37
Changes to External Respiration Path Section ............................ 39
Changes to Respiration Carrier Frequency Section; Added
Table 13 and Table 14 ...................................................................... 40
Changes to Pacing Artifact Detection Function (ADAS1000-4
Only) Section ................................................................................... 41
Changes to Table 15 ........................................................................ 42
Changes to Detection Algorithm Overview Section .................. 43
Changes to Pace Edge Threshold, Pace Level Threshold, Pace
Amplitude Threshold, Pace Validation Filters, and Pace Width
Filter Sections .................................................................................. 44
Changes to Evaluating Pace Detection Performance Section and
Added Pace Width Section ............................................................ 45
Changes to Voltage Reference Section ......................................... 57
Changes to Data Ready ( EE
AA) Section ..................................... 53
DRDY
Changes to Secondary Serial Interface Section and Table 25 .... 55
Changes to Bit 3, Table 28 .............................................................. 58
Changes to Table 43 ........................................................................ 68
Changes to Table 45 ........................................................................ 69
Changes to Table 51 and Table 52 ................................................. 72
Changes to Example 1: Initialize the Device for ECG Capture
and Start Streaming Data Section ................................................. 74
1/13—Rev. 0 to Rev. A
Changes to Endnote 2, Table 1 ........................................................ 3
Changes to Excitation Current Test Conditions/Comments ...... 5
Added Table 3 .................................................................................... 9
Changes to Figure 36, Figure 37, and Figure 39 ......................... 21
Changes to Respiration (ADAS1000-4 Model Only) Section
and Figure 63 ................................................................................... 34
Changes to Figure 64 ...................................................................... 35
Changes to Figure 65 ...................................................................... 36
Added Evaluating Pace Detection Performance Section ........... 40
Changes to Clocks Section ............................................................. 49
Changes to RESPAMP Bits Function Description, Table 29 ..... 55
11/12—Revision 0: Initial Version
Rev. B | Page 3 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 4 of 80
FUNCTIONAL BLOCK DIAGRAM
Figure 1. ADAS1000-4 3-Channel Full Featured Model
Table 1. Overview of Features Available from ADAS1000 Generics
Generic ECG Operation Right Leg Drive Respiration
Pace
Detection
Shield
Driver
Master
Interface1
Package
Option
ADAS1000 5 ECG channels Master/slave Yes Yes Yes Yes Yes LFCSP, LQFP
ADAS1000-1 5 ECG channels Master/slave Yes Yes Yes LFCSP
ADAS1000-22 5 ECG channels Slave LFCSP, LQFP
ADAS1000-3 3 ECG channels Master/slave Yes Yes Yes LFCSP, LQFP
ADAS1000-4 3 ECG channels Master/slave Yes Yes Yes Yes Yes LFCSP, LQFP
1 Master interface is provided for users wishing to utilize their own digital pace algorithm; see the Secondary Serial Interface section.
2 This is a companion device for increased channel count purposes. It has a subset of features and is not intended for standalone use. It may be used in conjunction with
any master device.
ELECTRODES
×3
VREF
REFOUTREFIN CAL_DAC_IO
AMP
ADC
RESPIRATION PATH
MUXES
AC
LEAD-OFF
DAC
CALIBRATION
DAC
AMP ADC
3× ECG PATH
FILTERS,
CONTROL,
AND
INTERFACE
LOGIC
PACE
DETECTION CS
SCLK
SDI
SDO
DRDY
GPIO3
GPIO1/MSCLK
GPIO2/MSDO
GPIO0/MCS
AC
LEAD-OFF
DETECTION
–
+
COMMON-
MODE AMP
RLD_SJ
DRIVEN
LEAD
AMP SHIELD
DRIVE
AMP
SHIELDRLD_OUT CM_IN
XTAL1 XTAL2
IOVDD
CLOCK GEN/OSC/
EXTERNAL CLK
SOURCE
EXT_RESP_LA
EXT_RESP_LL
VCM_REF
(1.3V)
CLK_IO
A
VDD
ADCVDD
DVDD
EXT_RESP_RA
CM_OUT/WCT
10kΩ
ADCVDD, DVDD
1.8V
REGULATORS
ADAS1000-4
BUFFER
RESPIRATION
DAC
10997-001
Data Sheet ADAS1000-3/ADAS1000-4
SPECIFICATIONS
AVDD = 3.3 V ± 5%, IOVDD = 1.65 V to 3.6 V, AGND = DGND = 0 V, REFIN tied to REFOUT, externally supplied crystal/clock =
8.192 MHz. Decoupling for reference and supplies as noted in the Power Supply, Grounding, and Decoupling Strategy section. TA =
−40°C to +85°C, unless otherwise noted. Typical specifications are mean values at TA = 25°C.
For specified performance, internal ADCVDD and DVDD linear regulators have been used. They may be supplied from external
regulators. ADCVDD = 1.8 V ± 5%, DVDD = 1.8 V ± 5%.
Front-end gain settings: GAIN 0 = ×1.4, GAIN 1 = ×2.1, GAIN 2 = ×2.8, GAIN 3 = ×4.2.
Table 2.
Parameter Min Typ Max Unit Test Conditions/Comments
ECG CHANNEL These specifications apply to the following pins:
ECG1_LA, ECG2_LL, ECG3_RA, CM_IN (CE mode),
EXT_RESP_xx pins when used in extend switch mode
Electrode Input Range Independent of supply
0.3 1.3 2.3 V GAIN 0 (gain setting ×1.4)
0.63 1.3 1.97 V GAIN 1 (gain setting ×2.1)
0.8 1.3 1.8 V GAIN 2 (gain setting ×2.8)
0.97 1.3 1.63 V GAIN 3 (gain setting ×4.2)
Input Bias Current −40 ±1 +40 nA Relates to each electrode input; over operating range;
dc and ac lead-off are disabled
−200 +200 nA AGND to AVDD
Input Offset −7 mV Electrode/vector mode with VCM = VCM_REF
GAIN 3
−7
mV
−15 mV GAIN 1
−22 mV GAIN 0
Input Offset Tempco1 ±2 μV/°C
Input Amplifier Input
Impedance2
1||10 GΩ||pF At 10 Hz
CMRR2 105 110 dB 51 kΩ imbalance, 60 Hz with ±300 mV differential dc
offset; per AAMI/IEC standards; with driven leg loop
closed
Crosstalk1 80 dB Between channels
Resolution2 19 Bits Electrode/vector mode, 2 kHz data rate, 24-bit data-word
18 Bits Electrode/vector mode, 16 kHz data rate, 24-bit data-
word
16 Bits Electrode/analog lead mode, 128 kHz data rate, 16-bit
data-word
Integral Nonlinearity Error 30 ppm GAIN 0; all data rates
Differential Nonlinearity Error 5 ppm GAIN 0
Gain2
N
after factory calibration. User calibration adjusts this
number.
GAIN 0 (×1.4) 4.9 µV/LSB At 19-bit level in 2 kHz data rate
9.81 μV/LSB At 18-bit level in 16 kHz data rate
39.24 μV/LSB At 16-bit level in 128 kHz data rate
GAIN 1 (×2.1) 3.27 μV/LSB At 19-bit level in 2 kHz data rate
6.54 μV/LSB At 18-bit level in 16 kHz data rate
26.15 μV/LSB At 16-bit level in 128 kHz data rate
GAIN 2 (×2.8) 2.45 μV/LSB At 19-bit level in 2 kHz data rate
4.9 μV/LSB At 18-bit level in 16 kHz data rate
19.62 μV/LSB At 16-bit level in 128 kHz data rate
GAIN 3 (×4.2) 1.63 μV/LSB No factory calibration for this gain setting
At 19-bit level in 2 kHz data rate
3.27 μV/LSB At 18-bit level in 16 kHz data rate
13.08 μV/LSB At 16-bit level in 128 kHz data rate
Rev. B | Page 5 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 6 of 80
Parameter Min Typ Max Unit Test Conditions/Comments
Gain Error −1 +0.01 +1 % GAIN 0 to GAIN 2, factory calibrated; programmable
user or factory calibration option enables; factory gain
calibration applies only to standard ECG interface
−2 +0.1 +2 % GAIN 3 setting, no factory calibration for this gain
Gain Matching −0.1 +0.02 +0.1 % GAIN 0 to GAIN 2
−0.5 +0.1 +0.5 % GAIN 3
Gain Tempco1 25 ppm/°C
Input Referred Noise1 GAIN 2, 2 kHz data rate, see Table 4
Analog Lead Mode 6 μV p-p 0.5 Hz to 40 Hz; high performance mode
10 μV p-p 0.05 Hz to 150 Hz; high performance mode
12 μV p-p 0.05 Hz to 150 Hz; low power mode
Electrode Mode 11 μV p-p 0.05 Hz to 150 Hz; high performance mode
12 μV p-p 0.05 Hz to 150 Hz; low power mode
Digital Lead Mode 14 μV p-p 0.05 Hz to 150 Hz; high performance mode
16 μV p-p 0.05 Hz to 150 Hz; low power mode
Power Supply Sensitivity2 100 dB At 120 Hz
Analog Channel Bandwidth1 65 kHz
Dynamic Range1 104 dB GAIN 0, 2 kHz data rate, −0.5 dBFS input signal, 10 Hz
Signal-to-Noise Ratio1 100 dB −0.5 dB FS input signal
COMMON-MODE INPUT CM_IN pin
Input Voltage Range 0.3 2.3 V
Input Impedance2 1||10 GΩ||pF
Input Bias Current −40 ±1 +40 nA Over operating range; dc and ac lead-off disabled
−200 +200 nA AGND to AVDD
COMMON-MODE OUTPUT CM_OUT pin
VCM_REF 1.28 1.3 1.32 V Internal voltage; independent of supply
Output Voltage, VCM 0.3 1.3 2.3 V No dc load
Output Impedance1 0.75 kΩ Not intended to drive current
Short-Circuit Current1 4 mA
Electrode Summation
Weighting Error2
1 % Resistor matching error
RESPIRATION FUNCTION
(ADAS1000-4 ONLY)
These specifications apply to the following pins:
EXT_RESP_LA, EXT_RESP_LL, EXT_RESP_RA and selected
internal respiration paths (Lead I, Lead II, Lead III)
Input Voltage Range 0.3 2.3 V AC-coupled, independent of supply
Input Voltage Range (Linear
Operation)
1.8/gain V p-p Programmable gain (10 states)
Input Bias Current −10 ±1 +10 nA Applies to EXT_RESP_xx pins over AGND to AVDD
Input Referred Noise1 0.85 μV rms
Frequency2 46.5 to 64 kHz Programmable frequency, see Table 30
Excitation Current Respiration drive current corresponding to differential
voltage programmed by the RESPAMP bits in the
RESPCTL register; internal respiration mode, cable
5 kΩ/200 pF, 1.2 kΩ chest impedance
64 μA p-p Drive Range A
32 μA p-p
Drive Range B2
16 μA p-p
Drive Range C2
8 μA p-p
Drive Range D2
Resolution2 24 Bits Update rate 125 Hz
Measurement Resolution1 0.2 Ω Cable <5 kΩ/200 pF per electrode, body resistance
modeled as 1.2 kΩ
0.02 Ω No cable impedance, body resistance modeled as 1.2 kΩ
In-Amp Gain1 1 to 10 Digitally programmable in steps of 1
Gain Error 1 % LSB weight for GAIN 0 setting
Gain Tempco1 25 ppm/C
Data Sheet ADAS1000-3/ADAS1000-4
Parameter Min Typ Max Unit Test Conditions/Comments
RIGHT LEG DRIVE/DRIVEN LEAD
Output Voltage Range 0.2 AVDD − 0.2 V
RLD_OUT Short-Circuit Current −5 ±2 +5 mA External protection resistor required to meet
regulatory patient current limits; output shorted to
AVDD/AGND
Closed-Loop Gain Range2 25 V/V
Slew Rate2 200 mV/ms
Input Referred Noise1 8 μV p-p 0.05 Hz to 150 Hz
Amplifier GBP2 1.5 MHz
DC LEAD-OFF Internal current source, pulls up open ECG pins;
programmable in 10 nA steps: 10 nA to 70 nA
Lead-Off Current Accuracy ±10 % Of programmed value
High Threshold Level1 2.4 V Inputs are compared to threshold levels; if inputs
exceed levels, lead-off flag is raised
Low Threshold Level1 0.2 V
Threshold Accuracy 25 mV
AC LEAD-OFF Programmable in 4 steps: 12.5 nA rms, 25 nA rms,
50 nA rms, 100 nA rms
Frequency Range 2.039 kHz Fixed frequency
Lead-Off Current Accuracy ±10 % Of programmed value, measured into low impedance
REFIN
Input Range2 1.76 1.8 1.84 V Channel gain scales directly with REFIN
Input Current 113 μA Per active ADC
450 675 950 μA Three ECG channels and respiration enabled
REFOUT
drive other components reference inputs directly,
must be buffered externally
Output Voltage, VREF 1.785 1.8 1.815 V
Reference Tempco1 ±10 ppm/°C
Output Impedance2 0.1 Ω
Short-Circuit Current1 4.5 mA Short circuit to ground
Voltage Noise1 33 μV p-p 0.05 Hz to 150 Hz (ECG band)
17 μV p-p 0.05 Hz to 5 Hz (respiration)
CALIBRATION DAC Available on CAL_DAC_IO (output for master, input for
slave)
DAC Resolution 10 Bits
Full-Scale Output Voltage 2.64 2.7 2.76 V No load, nominal FS output is 1.5 × REFOUT
Zero-Scale Output Voltage 0.24 0.3 0.36 V No load
DNL −1 +1 LSB
Output Series Resistance2 10 kΩ Not intended to drive low impedance load, used for
slave CAL_DAC_IO configured as an input
Input Current ±5 nA When used as an input
CALIBRATION DAC TEST TONE
Output Voltage 0.9 1 1.1 mV p-p Rides on common-mode voltage, VCM_REF = 1.3 V
Square Wave 1 Hz
Low Frequency Sine Wave 10 Hz
High Frequency Sine Wave 150 Hz
SHIELD DRIVER
Output Voltage Range 0.3 2.3 V Rides on common-mode voltage (VCM)
Gain 1 V/V
Offset Voltage −20 +20 mV
Short-Circuit Current 15 25 μA Output current limited by internal series resistance
Stable Capacitive Load2 10 nF
CRYSTAL OSCILLATOR Applied to XTAL1 and XTAL2
Frequency2 8.192 MHz
Start-Up Time2 15 ms Internal startup
Rev. B | Page 7 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Parameter Min Typ Max Unit Test Conditions/Comments
CLOCK_IO
is configured as an input when the device is
programmed as a slave
Operating Frequency2 8.192 MHz
Input Duty Cycle2 20 80 %
Output Duty Cycle2 50 %
DIGITAL INPUTS Applies to all digital inputs
Input Low Voltage, VIL 0.3 × IOVDD V
Input High Voltage, VIH 0.7 × IOVDD V
Input Current, IIH, IIL −1 +1 μA
−20 +20 μA EE
AA has an internal pull-up resistor
RESET
Pin Capacitance2 3 pF
DIGITAL OUTPUTS
Output Low Voltage, VOL 0.4 V ISINK = 1 mA
Output High Voltage, VOH IOVDD − 0.4 V ISOURCE = −1 mA
Output Rise/Fall Time 4 ns Capacitive load = 15 pF, 20% to 80%
DVDD REGULATOR
Output Voltage 1.75 1.8 1.85 V
Available Current
1
1
mA
Short-Circuit Current Limit 40 mA
ADCVDD REGULATOR Internal 1.8 V regulator for ADCVDD; not
recommended as a supply for other circuitry
Output Voltage 1.75 1.8 1.85 V
Short-Circuit Current Limit 40 mA
POWER SUPPLY RANGES2
AVDD 3.15 3.3 5.5 V
IOVDD 1.65 3.6 V
ADCVDD 1.71 1.8 1.89 V If applied by external 1.8 V regulator
DVDD 1.71 1.8 1.89 V If applied by external 1.8 V regulator
POWER SUPPLY CURRENTS
AVDD Standby Current
785
975
μA
IOVDD Standby Current 1 60 μA
EXTERNALLY SUPPLIED ADCVDD
AND DVDD
All three channels enabled, RLD enabled, pace enabled
AVDD Current 2.4 4.1 mA High performance mode
2.2 4.1 mA Low performance mode
3.2 mA High performance mode, respiration enabled
ADCVDD Current 4.5 6.5 mA High performance mode
3.3 5.5 mA Low performance mode
5.4 mA High performance mode, respiration enabled
DVDD Current 2.0 4 mA High performance mode
1.1 3 mA Low performance mode
2.0 mA High performance mode, respiration enabled
INTERNALLY SUPPLIED ADCVDD
AND DVDD
All three channels enabled, RLD enabled, pace enabled
AVDD Current 9 12.6 mA High performance mode
6.6 9.6 mA Low performance mode
11
14.6
mA
POWER DISSIPATION All 3 channels enabled, RLD enabled, pace enabled
Externally Supplied ADCVDD
and DVDD3
Three Input Channels and RLD 19.6 mW High performance (low noise)
15.2 mW Low power mode
Internally Supplied ADCVDD
and DVDD
All three channels enabled, RLD enabled, pace enabled
Three Input Channels and RLD 29.7 mW High performance (low noise)
21.8 mW Low power mode
Rev. B | Page 8 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Parameter Min Typ Max Unit Test Conditions/Comments
OTHER FUNCTIONS4
Power Dissipation
Respiration 7.6 mW
Shield Driver 150 μW
EXTERNALLY SUPPLIED ADCVDD
AND DVDD
Two electrodes enabled for one lead measurement,
RLD enabled, pace enabled
AVDD Current 1.9 3.7 mA High performance mode
1.7 3.7 mA Low performance mode
ADCVDD Current
3.6
5.5
mA
2.5
4.5
mA
DVDD Current 1.7 4 mA High performance mode
0.9 3 mA Low performance mode
INTERNALLY SUPPLIED ADCVDD
AND DVDD
Two electrodes enabled for one lead measurement,
RLD enabled, pace enabled
AVDD Current 7.3 10.7 mA High performance mode
5.3 8.2 mA Low performance mode
POWER DISSIPATION Two electrodes enabled for one lead measurement,
RLD enabled, pace enabled
Externally Supplied ADCVDD
and DVDD3
Two Input Channels and RLD 15.8 mW High performance (low noise)
11.7 mW Low power mode
Internally Supplied ADCVDD
and DVDD
Two Input Channels and RLD
24
mW
17.5
mW
1 Guaranteed by characterization, not production tested.
2 Guaranteed by design, not production tested.
3 ADCVDD and DVDD can be powered from an internal LDO or, alternatively, can be powered from an external 1.8 V rail, which may result in a lower power solution.
4 Pace is a digital function and incurs no power penalty.
Rev. B | Page 9 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
NOISE PERFORMANCE
Table 3. Typical Input Referred Noise over a 0.5 sec Window (μV p-p)1
Mode Data Rate2
GAIN 0 (×1.4)
±1 VCM
GAIN 1 (×2.1)
±0.67 VCM
GAIN 2 (×2.8)
±0.5 VCM
GAIN 3 (×4.2)
±0.3 VCM
Analog Lead Mode3
High Performance Mode 2 kHz (0.5 Hz to 40 Hz) 8 6 5 4
2 kHz (0.05 Hz to 150 Hz) 14 11 9 7.5
1 Typical values measured at 25°C, not subject to production test.
2 Data gathered using the 2 kHz packet/frame rate is measured over 0.5 seconds. The ADAS1000-3/ADAS1000-4 internal programmable low-pass filter is configured for
either 40 Hz or 150 Hz bandwidth. The data is gathered and post processed using a digital filter of either 0.05 Hz or 0.5 Hz to provide data over noted frequency bands.
3 Analog lead mode as shown in Figure 56.
Table 4. Typical Input Referred Noise (μV p-p)1
Mode Data Rate2
GAIN 0 (×1.4)
±1 VCM
GAIN 1 (×2.1)
±0.67 VCM
GAIN 2 (×2.8)
±0.5 VCM
GAIN 3 (×4.2)
±0.3 VCM
Analog Lead Mode3
High Performance Mode 2 kHz (0.5 Hz to 40 Hz) 12 8.5 6 5
2 kHz (0.05 Hz to 150 Hz) 20 14.5 10 8.5
2 kHz (0.05 Hz to 250 Hz) 27 18 14.5 10.5
2 kHz (0.05 Hz to 450 Hz) 33.5 24 19 13.5
16 kHz 95 65 50 39
128 kHz 180 130 105 80
Low Power Mode 2 kHz (0.5 Hz to 40 Hz) 13 9.5 7.5 5.5
2 kHz (0.05 Hz to 150 Hz) 22 15.5 12 9
16 kHz 110 75 59 45
128 kHz 215 145 116 85
Electrode Mode4
High Performance Mode 2 kHz (0.5 Hz to 40 Hz) 13 9.5 8 5.5
2 kHz (0.05 Hz to 150 Hz) 21 15 11 9
2 kHz (0.05 Hz to 250 Hz) 26 19 15.5 11.5
2 kHz (0.05 Hz to 450 Hz) 34.5 25 20.5 14.5
16 kHz 100 70 57 41
128 kHz 190 139 110 85
Low Power Mode 2 kHz (0.5 Hz to 40 Hz) 14 9.5 7.5 5.5
2 kHz (0.05 Hz to 150 Hz) 22 15.5 12 9.5
16 kHz 110 75 60 45
128 kHz 218 145 120 88
Digital Lead Mode5, 6
High Performance Mode 2 kHz (0.5 Hz to 40 Hz) 16 11 9 6.5
2 kHz (0.05 Hz to 150 Hz)
25
19
15
10
2 kHz (0.05 Hz to 250 Hz) 34 23 18 13
2 kHz (0.05 Hz to 450 Hz) 46 31 24 17.5
16 kHz 130 90 70 50
Low Power Mode 2 kHz (0.5 Hz to 40 Hz) 18 12.5 10 7
2 kHz (0.05 Hz to 150 Hz) 30 21 16 11
16 kHz 145 100 80 58
1 Typical values measured at 25°C, not subject to production test.
2 Data gathered using the 2 kHz packet/frame rate is measured over 20 seconds. The ADAS1000-3/ADAS1000-4 internal programmable low-pass filter is configured for
either 40 Hz or 150 Hz bandwidth. The data is gathered and post processed using a digital filter of either 0.05 Hz or 0.5 Hz to provide data over noted frequency bands.
3 Analog lead mode as shown in Figure 56.
4 Single-ended input electrode mode as shown in Figure 59. Electrode mode refers to common electrode A, common electrode B, and single-ended input electrode
configurations.
5 Digital lead mode as shown in Figure 57.
6 Digital lead mode is available in 2 kHz and 16 kHz data rates.
Rev. B | Page 10 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Rev. B | Page 11 of 80
TIMING CHARACTERISTICS
Standard Serial Interface
AVDD = 3.3 V ± 5%, IOVDD = 1.65 V to 3.6 V, AGND = DGND = 0 V, REFIN tied to REFOUT, externally supplied crystal/clock =
8.192 MHz. TA = −40°C to +85°C, unless otherwise noted. Typical specifications are mean values at TA = 25°C.
Table 5.
IOVDD
Parameter1 3.3 V 2.5 V 1.8 V Unit Description
Output Rate2 2 128 kHz Across specified IOVDD supply range; three programmable output data
rates available as configured in FRMCTL register (see Table 37) 2 kHz,
16 kHz, 128 kHz; use skip mode for slower rates.
SCLK Cycle Time 25 40 50 ns min See Table 21 for details on SCLK frequency vs. packet data/frame rates.
tCSSA 8.5 9.5 12 ns min
ACSE
A valid setup time to rising SCLK.
tCSHA 3 3 3 ns min
ACSE
A valid hold time to rising SCLK.
tCH 8 8 8 ns min SCLK high time.
tCL 8 8 8 ns min SCLK low time.
tDO 8.5 11.5 20 ns typ SCLK falling edge to SDO valid delay; SDO capacitance of 15 pF.
11 19 24 ns max
tDS 2 2 2 ns min SDI valid setup time from SCLK rising edge.
tDH 2 2 2 ns min SDI valid hold time from SCLK rising edge.
tCSSD 2 2 2 ns min
ACSE
A valid setup time from SCLK rising edge.
tCSHD 2 2 2 ns min
ACSE
A valid hold time from SCLK rising edge.
tCSW 25 40 50 ns min
ACSE
A high time between writes (if used). Note that ACSE
A is an optional input,
it may be tied permanently low. See a full description in the Serial
Interfaces section.
tDRDY_CS2 0 0 0 ns min
ADRDYE
A to ACSE
A setup time.
tCSO 6 7 9 ns typ
Delay from ACSE
A assert to SDO active.
ARESETE
A Low Time2 20 20 20 ns min
Minimum pulse width; ARESETE
A is edge triggered.
1 Guaranteed by characterization, not production tested.
2 Guaranteed by design, not production tested.
Figure 2. Data Read and Write Timing Diagram (CPHA = 1, CPOL = 1)
DB[30]DB[31] DB[0]DB[1]DB[29] DB[25] DB[24] DB[23]
SCLK
CS
SDI
t
CH
t
CL
t
CSSA
t
CSHA
t
CSHD
t
CSSD
t
DH
t
DS
t
CSW
SDO
t
DO
R/W
MSB LSB
DATAADDRESS
DO_25 DO_1 DO_0
DO_29DO_30DO_31DRDY
MSB LSB
t
CSO
10997-002
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 12 of 80
Figure 3. Starting Read Frame Data (CPHA = 1, CPOL = 1)
Figure 4. Data Read and Write Timing Diagram (CPHA = 0, CPOL = 0)
SCLK
CS
SDI
t
CH
t
CSSA
t
CSHA
t
CSHD
t
CSSD
t
DH
t
DS
SDO
t
DO
DB[30]
N
DB[31]
N
R/W
DB[29]
NDB[25]
N
MSB LSB
DB[24]
N
DATA
MSB LSB
DRDY
t
CSO
DRDY
t
DRDY_CS
DB[30]
N + 1
DB[31]
N + 1 DB[0]
N + 1
MSB LSB
DB[1]
N + 1
DATA = NOP or 0x40
MSB
DB[31]
NDB[0]
N
DB[30]
NDB[1]
N
LSB
DB[30]
N – 1
DB[31]
N – 1 DB[1]
N – 1 DB[0]
N – 1
DB[23]
N – 1
DB[25]
N – 1
PREVIOUS DATA HEADER (FIRST WORD O F FRAME)
DB[1]
DB[23]
t
CL
t
CSW
ADDRESS = 0x40 (FRAMES)
DB[24]
N – 1
10997-003
SCLK
CS
SDI
t
CH
t
CL
t
CSHA
t
CSHD
t
CSSD
t
DH
t
DS
t
CSW
SDO DO_28
LAST
DO_29
LAST
DO_30
LAST
DO_1
LAST
DO_0
LAST
DB[30] DB[29] DB[28] DB[24] DB[1] DB[0]
LSB
MSB
MSB
LSB
t
DO
t
DO
DATAADDRESS
R/W
DO_31
t
CSSA
DB[31] DB[2]
10997-004
Data Sheet ADAS1000-3/ADAS1000-4
Rev. B | Page 13 of 80
Secondary Serial Interface (Master Interface for Customer-Based Digital Pace Algorithm) ADAS1000-4 Only
AVDD = 3.3 V ± 5%, IOVDD = 1.65 V to 3.6 V, AGND = DGND = 0 V, REFIN tied to REFOUT, externally supplied crystal/clock =
8.192 MHz. TA = −40°C to +85°C, unless otherwise noted. Typical specifications are mean values at TA = 25°C. The following timing
specifications apply for the master interface when the ECGCTL register is configured for high performance mode (ECGCTL[3] = 1), see
Table 28.
Table 6.
Parameter1 Min Typ Max Unit Description
Output Frame Rate2 128 kHz All five 16-bit ECG data-words are available at frame rate of 128 kHz only
fSCLK2
2.5 × crystal
frequency
MHz Crystal frequency = 8.192 MHz
tMCSSA 24.4 ns
AMCSE
A valid setup time
tMDO 0 ns MSCLK rising edge to MSDO valid delay
tMCSHD 48.8 ns
AMCSE
A valid hold time from MSCLK falling edge
tMCSW 2173 ns
AMCSE
A high time, SPIFW = 0, AMCSE
A asserted for entire frame as shown in
Figure 5, and configured in Table 33
2026 ns
AMCSE
A high time, SPIFW = 1, AMCSE
A asserted for each word in frame as shown in
Figure 6 and configured in Table 33
1 Guaranteed by characterization, not production tested.
2 Guaranteed by design, not production tested.
Figure 5. Data Read and Write Timing Diagram for SPIFW = 0, Showing Entire Packet Of Data (Header, 5 ECG Word = [ECG1, ECG2, ECG3 and 2 Words with Zeros],
and CRC Word)
Figure 6. Data Read and Write Timing Diagram for SPIFW = 1, Showing Entire Packet Of Data (Header, 5 ECG Word = [ECG1, ECG2, ECG3 and 2 Words with Zeros],
and CRC Word)
t
MSCLK
t
MCSSA
t
MSCLK
2
MSCLK
MCS
t
MCSHD
MSDO D0_15
t
MDO
MSB
D0_14 D0_1 D1_15
LSB
SPIFW = 0*
D5_0
D0_0 D1_14
*SPIFW = 0 PRO V I DES M CS FOR EACH F RAME , S CL K STAYS HI G H FOR 1/ 2 MS CL K CYCL E BE T W E EN E ACH WORD.
D6_15
MSB
D6_14
MSB LSB
D6_0
LSB
HEADER: 0xF AND 12-BI T CO UNT E R 5 × 16-B IT E CG DATA 16-BIT CRC WORD
t
MCSW
10997-105
tMSCLK
tMCSSA tMCSHD
MSCLK
MCS
MSDO
SPIFW = 1*
tMSCLK
tMCSW
D0_15
t
MDO
MSB
D0_14 D0_1 D1_15
LSB
D5_0
D0_0
D1_14 D6_15
MSB
D6_14
MSB LSB
D6_0
LSB
5 × 16-BI T ECG DATAHEADER: 0xF AND 12-BI T CO UNTER 16-BIT CR C W ORD
*
SP I FW = 1 P ROV I D ES M CS FOR E AC H F RA M E , SCLK S T AYS HIG H FO R 1 M S C L K C Y CLE BE TW E E N E A CH WO R D.
10997-005
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 14 of 80
ABSOLUTE MAXIMUM RATINGS
Table 7.
Parameter Rating
AVDD to AGND −0.3 V to +6 V
IOVDD to DGND −0.3 V to +6 V
ADCVDD to AGND −0.3 V to +2.5 V
DVDD to DGND −0.3 V to +2.5 V
REFIN/REFOUT to REFGND −0.3 V to +2.1 V
ECG and Analog Inputs to AGND −0.3 V to AVDD + 0.3 V
Digital Inputs to DGND −0.3 V to IOVDD + 0.3 V
REFIN to ADCVDD ADCVDD + 0.3 V
AGND to DGND −0.3 V to + 0.3 V
REFGND to AGND −0.3 V to + 0.3 V
ECG Input Continuous Current ±10 mA
Storage Temperature Range −65°C to +125°C
Operating Junction Temperature Range −40°C to +85°C
Reflow Profile J-STD-20 (JEDEC)
Junction Temperature 150°C max
ESD
HBM 2500 V
FICDM 1000 V
Stresses at or above those listed under Absolute Maximum
Ratings may cause permanent damage to the product. This is a
stress rating only; functional operation of the product at these
or any other conditions above those indicated in the operational
section of this specification is not implied. Operation beyond
the maximum operating conditions for extended periods may
affect product reliability.
THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 8. Thermal Resistance1
Package Type θJA Unit
56-Lead LFCSP 35 °C/W
64-Lead LQFP 42.5 °C/W
1 Based on JEDEC standard 4-layer (2S2P) high effective thermal conductivity
test board (JESD51-7) and natural convection.
ESD CAUTION
Data Sheet ADAS1000-3/ADAS1000-4
8BPIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
Figure 7. ADAS1000-3, 64-Lead LQFP Pin Configuration
Figure 8. ADAS1000-3, 56-Lead LFCSP Pin Configuration
Figure 9. ADAS1000-4, 64-Lead LQFP Pin Configuration
Figure 10. ADAS1000-4, 56-Lead LFCSP Pin Configuration
DGND
IOVDD
GPIO0/MCS
GPIO1/MSCLK
GPIO2/MSDO
GPIO3
DGND
CS
DRDY
SDI
SCLK
SDO
IOVDD
DGND
NC
NC
DGND
DVDD
SYNC_GANG
PD
RESET
ADCVDD
AGND
AGND
AVDD
VREG_EN
SHIELD
CAL_DAC_IO
NC
AVDD
NC
NC
PIN 1
ADAS1000-3
64-LE AD LQFP
TOP VIEW
(Not t o Scal e)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17181920 21 222324 25 26 2728 293031 32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
495051
52
53
54
55
565758
59
60
616263
64
NC
NC
REFGND
REFOUT
REFIN
ECG1_LA
ECG2_LL
NC
AGND
NC
NC
AGND
NC
NC
NC
ECG3_RA
CM_OUT/WCT
RLD_SJ
AVDD
AGND
AGND
ADCVDD
XTAL1
RLD_OUT
DGND
CLK_IO
CM_IN
AVDD
NC
DVDD
NC
XTAL2
NOTES
1. PINS LABELED NC CAN BE ALLOWED TO FLOAT, BUT IT IS BETTER TO CONNECT
THESE PINS TO GROUND. AVOID ROUTING HIGH SPEED SIGNALS THROUGH THESE
PINS BE CAUS E NOIS E COUPL ING M AY RE S ULT.
10997-007
PIN 1
INDICATOR
1
AGND
2
NC
3
NC
4
NC
5
NC
6
REFGND
7
REFOUT
8
REFIN
9
ECG1_LA
10
ECG2_LL
11
ECG3_RA
12
NC
13
NC
14
AGND
35
DGND
36
CS
37
DRDY
38
SDI
39
SCLK
40
SDO
41
IOVDD
42
DGND
NOTES
1. PINS LABELED NC CAN BE ALLOWED TO FLOAT, BUT IT IS BETTER
TO CONNECT THESE PINS TO GROUND. AVOID ROUTING HIGH SPEED
SIGNALS THROUGH THE S E P INS BECAUS E NOIS E COUPL ING
MAY RESULT.
2. THE EXPOSED PAD IS ON THE TOP OF T HE PACKAGE;
IT IS CONNECTED TO THE MOST NEGATIVE POTENTIAL, AGND.
34
GPIO3
33
GPIO2/MSDO
32
GPIO1/MSCLK
31
GPIO0/MCS
30
IOVDD
29
DGND
15
AVDD
16
CM_IN
17
RLD_OUT
19
CM_OUT/WCT
21
AGND
20
AVDD
22
AGND
23
ADCVDD
24
XTAL1
25
XTAL2
26
CLK_IO
27
DVDD
28
DGND
18
RLD_SJ
45
SYNC_GANG
46
PD
47
RESET
48
ADCVDD
49
AGND
50
AGND
51
AVDD
52
VREG_EN
53
SHIELD
54
CAL_DAC_IO
44
DVDD
43
DGND
ADAS1000-3
56-LE AD LFCS P
TOP VIEW
(Not t o Scal e)
55
NC
56
AVDD
10997-006
DGND
IOVDD
____
GPIO0/MCS
GPIO1/MSCLK
GPIO2/MSDO
GPIO3
DGND
CS
DRDY
SDI
SCLK
SDO
IOVDD
DGND
NC
NC
DGND
DVDD
SYNC_GANG
PD
RESET
ADCVDD
AGND
AGND
AVDD
VREG_EN
SHIELD/RESPDAC_LA
CAL_DAC_IO
RESPDAC_LL
AVDD
NC
NC
PIN 1
ADAS1000-4
64-LE AD LQFP
TOP VIEW
(Not t o Scal e)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
495051525354555657585960616263
64
EXT_RESP_LA
EXT_RESP_LL
REFGND
REFOUT
REFIN
ECG1_LA
ECG2_LL
EXT_RESP_RA
AGND
NC
RESPDAC_RA
AGND
NC
NC
NC
ECG3_RA
CM_OUT/WCT
AVDD
AGND
AGND
ADCVDD
XTAL1
RLD_OUT
DGND
CLK_IO
CM_IN
AVDD
NC
DVDD
NC
XTAL2
RLD_SJ
NOTES
1. PINS LABELED NC CAN BE ALLOWED TO FLOAT, BUT IT IS BETTER TO
CONNECT THE S E P INS T O GROUND. AV OID ROUTING HIGH S P E E D
SIGNALS THROUGH THE S E P INS BECAUS E NOIS E COUPL ING
MAY RESULT.
10997-009
PIN 1
INDICATOR
1
AGND
2
RESPDAC_RA
3
EXT_RESP_RA
4
EXT_RESP_LL
5
EXT_RESP_LA
6
REFGND
7
REFOUT
8
REFIN
9
ECG1_LA
10
ECG2_LL
11
ECG3_RA
12
NC
13
NC
14
AGND
35
36
37
38
39
40
41
42
34
33
32
31
30
29
15
AVDD
16
CM_IN
17
RLD_OUT
19
CM_OUT/WCT
21
AGND
20
AVDD
22
AGND
23
ADCVDD
24
XTAL1
25
XTAL2
26
CLK_IO
27
DVDD
28
DGND
18
RLD_SJ
45
SYNC_GANG
46
PD
47
RESET
48
ADCVDD
49
AGND
50
AGND
51
AVDD
52
VREG_EN
53
SHIELD/RESPDAC_LA
54
CAL_DAC_IO
44
DVDD
43
DGND
ADAS1000-4
56-LE AD LFCS P
TOP VIEW
(Not t o Scal e)
55
RESPDAC_LL
56
AVDD
DGND
CS
DRDY
SDI
SCLK
SDO
IOVDD
DGND
GPIO3
GPIO2/MSDO
GPIO1/MSCLK
GPIO0/MCS
IOVDD
DGND
NOTES
1. PINS LABELED NC CAN BE ALLOWED TO FLOAT, BUT IT IS BETTER TO
CONNECT THE S E P INS T O GROUND. AV OID ROUTING HIGH S P E E D
SIGNALS THROUGH THE S E P INS BECAUS E NOIS E COUPL ING
MAY RESULT.
2. THE EXPOSED PAD IS ON THE TOP OF T HE PACKAGE;
IT IS CONNECTED TO THE MOST NEGATIVE POTENTIAL, AGND.
10997-008
Rev. B | Page 15 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 16 of 80
Table 9. Pin Function Descriptions
ADAS1000-3 Pin No. ADAS1000-4 Pin No.
Mnemonic Description
LQFP LFCSP LQFP LFCSP
18, 23,
58, 63
15, 20,
51, 56
18, 23, 58,
63
15, 20, 51,
56
AVDD Analog Supply. See recommendations for bypass capacitors in the Power Supply,
Grounding, and Decoupling Strategy section.
35, 46 30, 41 35, 46 30, 41 IOVDD Digital Supply for Digital Input/Output Voltage Levels. See recommendations for
bypass capacitors in the Power Supply, Grounding, and Decoupling Strategy section.
26, 55 23, 48 26, 55 23, 48 ADCVDD Analog Supply for ADC. There is an on-chip linear regulator providing the supply
voltage for the ADCs. These pins are primarily provided for decoupling purposes;
however, the pin may also be supplied by an external 1.8 V supply should the user wish
to use a more efficient supply to minimize power dissipation. In this case, use the
VREG_EN pin tied to ground to disable the ADCVDD and DVDD regulators. The
ADCVDD pin should not be used to supply other functions. See recommendations for
bypass capacitors in the Power Supply, Grounding, and Decoupling Strategy section.
30, 51 27, 44 30, 51 27, 44 DVDD Digital Supply. There is an on-chip linear regulator providing the supply voltage for the
digital core. These pins are primarily provided for decoupling purposes; however, the
pin may also be overdriven supplied by an external 1.8 V supply should the user wish to
use a more efficient supply to minimize power dissipation. In this case, use the
VREG_EN pin tied to ground to disable the ADCVDD and DVDD regulators. See
recommendations for bypass capacitors in the Power Supply, Grounding, and
Decoupling Strategy section.
2, 15, 24,
25, 56, 57
1, 14, 21,
22, 49, 50
2, 15, 24,
25, 56, 57
1, 14, 21,
22, 49, 50
AGND Analog Ground.
31, 34,
40, 47, 50
28, 29,
36, 42, 43
31, 34, 40,
47, 50
28, 29, 36,
42, 43
DGND Digital Ground.
59 19 59 19 VREG_EN Enables or disables the internal voltage regulators used for ADCVDD and DVDD. Tie this
pin to AVDD to enable or tie this pin to ground to disable the internal voltage
regulators.
10 6 10 6 ECG1_LA Analog Input, Left Arm (LA).
11 5 11 5 ECG2_LL Analog Input, Left Leg (LL).
12 4 12 4 ECG3_RA Analog Input, Right Arm (RA).
4 12 EXT_RESP_RA Optional External Respiration Input.
5 11 EXT_RESP_LL Optional External Respiration Input.
6 10 EXT_RESP_LA Optional External Respiration Input.
62 16 RESPDAC_LL Optional Path for Higher Performance Respiration Resolution, Respiration DAC Drive,
Negative Side 0.
60 18 SHIELD/
RESPDAC_LA
Shared Pin (User-Configured).
Output of Shield Driver (SHIELD).
Optional Path for Higher Performance Respiration Resolution, Respiration DAC Drive,
Negative Side 1 (RESPDAC_LA).
60 18 SHIELD Output of Shield Driver.
3 13 RESPDAC_RA Optional Path for Higher Performance Respiration Resolution, Respiration DAC Drive,
Positive Side.
22 52 22 52 CM_OUT/WCT Common-Mode Output Voltage (Average of Selected Electrodes). Not intended to drive
current.
19 55 19 55 CM_IN Common-Mode Input.
21 53 21 53 RLD_SJ Summing Junction for Right Leg Drive Amplifier.
20 54 20 54 RLD_OUT Output and Feedback Junction for Right Leg Drive Amplifier.
61 17 61 17 CAL_DAC_IO Calibration DAC Input/Output. Output for a master device, input for a slave. Not
intended to drive current.
9 7 9 7 REFIN Reference Input. For standalone mode, use REFOUT connected to REFIN. External 10 μF
capacitors with ESR < 0.2 Ω in parallel with 0.1 μF bypass capacitors to GND are
required and should be placed as close to the pin as possible. An external reference can
be connected to REFIN.
8 8 8 8 REFOUT Reference Output.
7 9 7 9 REFGND Reference Ground. Connect to a clean ground.
27, 28 47, 46 27, 28 47, 46 XTAL1, XTAL2 External crystal connects between these two pins; external clock drive should be
applied to CLK_IO. Each XTAL pin requires a 15 pF capacitor to ground.
29 45 29 45 CLK_IO Buffered Clock Input/Output. Output for a master device; input for a slave. Powers up in
high impedance.
41 35 41 35 ACSE Chip Select and Frame Sync, Active Low. ACSE
A can be used to frame each word or to frame
the entire suite of data in framing mode.
Data Sheet ADAS1000-3/ADAS1000-4
Rev. B | Page 17 of 80
ADAS1000-3 Pin No. ADAS1000-4 Pin No.
Mnemonic Description
LQFP LFCSP LQFP LFCSP
44 32 44 32 SCLK Clock Input. Data is clocked into the shift register on a rising edge and clocked out on a
falling edge.
43 33 43 33 SDI Serial Data Input.
53 25 53 25 APDE Power-Down, Active Low.
45 31 45 31 SDO Serial Data Output. This pin is used for reading back register configuration data and for
the data frames.
42 34 42 34 ADRDYE Digital Output. This pin indicates that conversion data is ready to be read back when
low, busy when high. When reading packet data, the entire packet must be read to
allow ADRDYE
A to return high.
54 24 54 24 ARESETE Digital Input. This pin has an internal pull-up resistor. This pin resets all internal nodes to
their power-on reset values.
52 26 52 26 SYNC_GANG Digital Input/Output (Output on Master, Input on Slave). Used for synchronization
control where multiple devices are connected together. Powers up in high impedance.
36 40 36 40 GPIO0/AMCSE General-Purpose I/O or Master 128 kHz SPI ACSE
A.
37 39 37 39 GPIO1/MSCLK General-Purpose I/O or Master 128 kHz SPI SCLK.
38 38 38 38 GPIO2/MSDO General-Purpose I/O or Master 128 kHz SPI SDO.
39 37 39 37 GPIO3 General-Purpose I/O.
1, 3, 4, 5,
6, 13, 14,
16, 17,
32, 33,
48, 49,
62, 64
2, 3, 10,
11, 12,
13, 16
1, 13, 14,
16, 17, 32,
33, 48, 49,
64
2, 3 NC No connect. Do not connect to these pins (see Figure 7, Figure 8, Figure 9, and
Figure 10).
57 57 EPAD Exposed Pad. The exposed pad is on the top of the package; it is connected to the most
negative potential, AGND.
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 18 of 80
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 11. Input Referred Noise for 0.5 Hz to 40 Hz Bandwidth, 2 kHz Data
Rate, GAIN 0 (1.4)
Figure 12. Input Referred Noise for 0.5 Hz to 40 Hz Bandwidth, 2 kHz Data
Rate, GAIN 3 (4.2)
Figure 13. Input Referred Noise for 0.5 Hz to 150 Hz Bandwidth, 2 kHz Data
Rate, GAIN 0 (1.4)
Figure 14. Input Referred Noise for 0.5 Hz to 150 Hz Bandwidth, 2 kHz Data
Rate, GAIN 3 (4.2)
Figure 15. ECG Channel Noise Performance over a 0.5 Hz to 40 Hz or 0.5 Hz to
150 Hz Bandwidth vs. Gain Setting
Figure 16. Typical Gain Error Across Channels
–6
–4
–2
0
2
4
6
8
INPUT REFERRED NOISE (µV)
TIME (Seconds)
0.5Hz T O 40Hz
GAIN SETTING 0 = 1.4
DATA RATE = 2kHz
10 SECONDS OF DAT A
012345678910
10997-039
–6
–4
–2
0
2
4
6
8
INP UT REFE RRED NO ISE
(
µV)
TIME (Seconds)
0.5Hz T O 40Hz
GAIN SE TT ING 3 = 4. 2
DATA RA TE = 2 kHz
10 SECONDS OF DATA
TIME (Seconds)
012345678910
10997-040
–15
–10
–5
0
5
10
15
INPUT REF E RR ED NO ISE (µV )
0.5Hz T O 150Hz
GAIN SETTING 0 = 1.4
DATA RATE = 2kHz
10 SECONDS OF DATA
TIME (Seconds)
012345678910
10997-041
–15
–10
–5
0
5
10
15
INPUT REF E RR ED NO ISE (µV )
0.5Hz T O 150Hz
GAIN SETTING 3 = 4.2
DATA RATE = 2kHz
10 SECONDS OF DATA
TIME (Seconds)
012345678910
10997-042
0
5
10
15
20
25
GAIN 0 GAIN 1 GAIN 2 GAI N 3
INPUT REFERRED NOIS
E
(µV)
GAIN SETTING
LA 15 0Hz
LA 40Hz
10997-043
0.010
0.012
0.014
0.016
0.018
0.020
LA LL RA V1 V2
GAIN ERROR (%)
AVDD = 3.3V
GAIN SETTING 0 = 1.4
10997-116
ELECTRODE INPUT
Data Sheet ADAS1000-3/ADAS1000-4
Figure 17. Typical Gain Error vs. Gain
Figure 18. Typical Gain Error for All Gain Settings Across Temperature
Figure 19. Typical ECG Channel Leakage Current over Input Voltage Range
vs. Temperature
Figure 20. DC Lead-Off Comparator Low Threshold vs. Temperature
Figure 21. DC Lead-Off Comparator High Threshold vs. Temperature
Figure 22. Filter Response with 40 Hz Filter Enabled, 2 kHz Data Rate; See
Figure 72 for Digital Filter Overview
0.001
0.021
0.041
0.061
0.081
0.101
0.121
GAI N 0 GAI N 1 GAI N 2 GAIN 3
GAI N E RROR ( %)
AVDD = 3. 3V
GAIN SETTING
10997-045
–0.35
–0.30
–0.25
–0.20
–0.15
–0.10
–0.05
0
0.05
0.10
0.15
–40 –20 020 40 60 80
GAI N E RROR ( %)
TEMPERATURE (°C)
GAI N E RROR G 0
GAI N E RROR G 1
GAI N E RROR G 2
GAI N E RROR G 3
AVDD = 3. 3V
GAIN SETTING 0 = 1.4
GAIN SETTING 1 = 2.1
GAIN SETTING 2 = 2.8
GAIN SETTING 3 = 4.2
10997-046
–5
–4
–3
–2
–1
0
1
2
3
4
5
0.3 0.8 1.3 1.8 2.3
LEAKAGE (n A)
VOLTAGE (V)
+85°C
+55°C
+25°C
–5°C
–40°C
AVDD = 3. 3V
GAIN SETTING 0 = 1.4
10997-047
0.180
0.185
0.190
0.195
0.200
0.205
0.210
0.215
–40 –20 020 40 60 80
THRESHOLD (V)
TEMPERATURE (°C)
ECG DC LEAD- OF F THRE S HOL D
RLD DC LEAD-OF F THRE S HOL D
AVDD = 3. 3V
10997-048
2.375
2.380
2.385
2.390
2.395
2.400
2.405
2.410
2.415
2.420
–40 –20 020 40 60 80
HIG H THRES HOL D ( V )
TEMPERATURE ( °C)
ECG DC LEAD- OF F THRE S HOL D
RLD DC LEAD-OF F THRE S HOL D
AVDD = 3. 3V
10997-049
–10
–9
–8
–7
–6
–5
–4
–3
–2
–1
0
110 100 1k
GAI N (dB)
FREQUENCY (Hz)
AVDD = 3. 3V
10997-050
Rev. B | Page 19 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 20 of 80
Figure 23. Filter Response with 150 Hz Filter Enabled, 2 kHz Data Rate; See
Figure 72 for Digital Filter Overview
Figure 24. Filter Response with 250 Hz Filter Enabled, 2 kHz Data Rate; See
Figure 72 for Digital Filter Overview
Figure 25. Filter Response with 450 Hz Filter Enabled, 2 kHz Data Rate; See
Figure 72 for Digital Filter Overview
Figure 26. Analog Channel Bandwidth
Figure 27. Filter Response Running at 128 kHz Data Rate; See Figure 72 for
Digital Filter Overview
Figure 28. Typical Internal VREF vs. Temperature
–10
–9
–8
–7
–6
–5
–4
–3
–2
–1
0
1 10 100 1k
FREQUENCY (Hz)
GAIN (dB)
AVDD = 3.3V
10997-051
–10
–9
–8
–7
–6
–5
–4
–3
–2
–1
0
1 10 100 1k
FREQUENCY (Hz)
GAIN (dB)
10997-052
–10
–9
–8
–7
–6
–5
–4
–3
–2
–1
0
FREQUENCY (Hz)
1 10 100 1k
GAIN (dB)
AVDD = 3.3V
10997-053
–6
–5
–4
–3
–2
–1
0
FREQUENCY (Hz)
1 10 100 1k 10k 100k
GAIN (dB)
AVDD = 3.3V
10997-054
–9
–8
–7
–6
–5
–4
–3
–2
–1
0
FREQUENCY (Hz)
GAIN (dB)
1 10 100 1k 10k 100k
AVDD = 3.3V
10997-055
1.7965
1.7970
1.7975
1.7980
1.7985
1.7990
1.7995
1.8000
1.8005
1.8010
–40–200 20406080
VOL
T
AGE (V )
TEMPERAT URE (°C)
10997-056
Data Sheet ADAS1000-3/ADAS1000-4
Figure 29. VCM_REF vs. Temperature
Figure 30. Typical AVDD Supply Current vs. Temperature, Using Internal
ADVCDD/DVDD Supplies
Figure 31. Typical AVDD Supply Current vs. Temperature, Using Externally
Supplied ADVCDD/DVDD
Figure 32. Typical AVDD Supply Current vs. Temperature in Standby Mode
Figure 33. Typical AVDD Supply Current vs. AVDD Supply Voltage
Figure 34. Respiration with 200 mΩ Impedance Variation, Using Internal
Respiration Paths and Measured with a 0 Ω Patient Cable
TEMPERATURE ( °C)
1.2970
1.2975
1.2980
1.2985
1.2990
1.2995
1.3000
1.3005
1.3010
–40 –20 0
20
40 60 80
VOLTAGE (V)
AVDD = 3. 3V
10997-057
TEMPERATURE ( °C)
12.20
12.25
12.30
12.35
12.40
12.45
12.50
–40 –20 020 40 60 80
AVDD SUP PLY CURRENT (mA)
AVDD = 3. 3V
3 ECG CHANNE LS E NABLED
INTERNAL LDO UTILIZED
HIGH PERFORMANCE/LOW NOISE MODE
10997-060
TEMPERATURE ( °C)
3.395
3.400
3.405
3.410
3.415
3.420
3.425
3.430
–40 –20 020 40 60 80
AVDD SUP PLY CURRENT (mA)
AVDD = 3. 3V
3 ECG CHANNE LS E NABLED
ADCVDD AND DVDD SUP P LI E D E X TERNALLY
HIGH PERFORMANCE/LOW NOISE MODE
10997-058
765
770
775
780
785
790
795
800
805
–40 –20 020 40 60 80
AVDD SUP PLY CURRENT (µA)
TEMPERATURE (°C)
AVDD = 3. 3V
10997-069
12.35
12.40
12.45
12.50
12.55
12.60
12.65
3.0 3.5 4.0 4.5 5.0 5.5 6.0
CURRENT (mA)
VOLTAGE (V)
LOW NOISE/HIGH
PERF ORMANCE M ODE
10997-059
0.142925 0 5 10 15 20 25 30
0.142930
0.142935
0.142940
0.142945
0.142950
0.142955
RESPIRATION MAGNITUDE (V)
TIME (Seconds)
AVDD = 3 .3V
ECG P ATH/DEFIB/CABLE IM PE DANCE = 0 Ω
PATI ENT IM PEDANCE = 1 kΩ
RESPIRATI ON RATE = 10 RESPPM
RESPAMP = 11 = 6 0µA p -p
RESPGAIN = 0011 = 4
10997-062
Rev. B | Page 21 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Figure 35. Respiration with 100 mΩ Impedance Variation, Using Internal
Respiration Paths and Measured with a 0 Ω Patient Cable
Figure 36. Respiration with 200 mΩ Impedance Variation, Using Internal
Respiration Paths and Measured with a 5 kΩ Patient Cable
Figure 37. Respiration with 200 mΩ Impedance Variation, Using External
Respiration DAC Driving a 100 pF External Capacitor and Measured with a
0 Ω Patient Cable
Figure 38. Respiration with 200 mΩ Impedance Variation, Using External
Respiration DAC Driving a 100 pF External Capacitor and Measured with a
5 kΩ Patient Cable
Figure 39. Respiration with 200 mΩ Impedance Variation, Using External
Respiration DAC Driving a 1 nF External Capacitor and Measured with a
1.5 kΩ Patient Cable
Figure 40. Respiration with 100 mΩ Impedance Variation, Using an External
Respiration DAC Driving a 1 nF External Capacitor and Measured with a
1.5 kΩ Patient Cable
0 5 10 15 20 25 30
TIME (Seconds)
0.121115
0.121120
0.121125
0.121130
0.121135
0.121140
0.121145
RESPIRAT IO N M AGNITUDE ( V )
AVDD = 3. 3V
ECG PATH/DEFIB/CABLE IMPEDANCE = 0Ω
PATIENT IMPEDANCE = 1kΩ
RESPIRAT IO N RATE = 10RE S P P M
RESPAM P = 11 = 60µA p - p
RESPGAI N = 0011 = 4
10997-063
0 5 10 15 20 25 30
0.663130
0.663135
0.663140
0.663145
0.663150
0.663155
0.663160
RESPIRAT IO N M AGNITUDE ( V )
TIME (Seconds)
AVDD = 3 .3V
ECG P ATH/DEFIB/CABLE IM PE DANCE = 5k Ω
PATI ENT IM PEDANCE = 1 kΩ
RESPIRATI ON RATE = 10 RESPPM
RESPAMP = 11 = 6 0µA p- p
RESPGAIN = 0011 = 4
10997-064
0 5 10 15 20 25 30
TIME (Seconds)
0.062335
0.062340
0.062345
0.062350
0.062355
0.062360
0.062365
RESPIRATION MAGNITUDE (V)
AVDD = 3 .3V
ECG PATH/DEFIB/CABLE IMPEDANCE = 0Ω
PATIENT IMPEDANCE = 1kΩ
EXTCAP = 10 0pF
RESPI RATION RATE = 10 RESPPM
RESPAMP = 11 = 6 0µA p- p
RESPGAIN = 0011 = 4
10997-065
0 5 10 15 20 25 30
TIME (Seconds)
RESPIRATION MAGNITUDE (V)
0.517360
0.517365
0.517370
0.517375
0.517380
0.517385
0.517390
AVDD = 3 .3V
ECG P ATH/DEFIB/CABLE IM PE DANCE = 5k Ω/250pF
PATI ENT IM PEDANCE = 1 kΩ
EXTCAP= 10 0pF
RESPIRATI ON RATE = 10 RESPPM
RESPAMP = 11 = 6 0µA p- p
RESPGAIN = 0011 = 4
10997-067
0 5 10 15 20 25 30
TIME ( S econds)
0.159745
0.159750
0.159755
0.159760
0.159765
0.159770
0.159775
RESPIRATION MAGNITUDE (V)
AVDD = 3 .3V
ECG PATH/DEFIB/CABLE IMPEDANCE = 1.5kΩ/600pF
PATIENT IMPEDANCE = 1kΩ
EXTCAP = 1nF
RESPIRATI ON RATE = 10 RESPPM
RESPAMP = 11
RESPGAIN = 0001 = 1
10997-139
0 5 10 15 20 25 30
TIME (Seconds)
0.159118
0.159119
0.159120
0.159121
0.159122
0.159123
0.159124
0.159125
0.159126
RESPIRATION MAGNITUDE (V)
EXTCAP = 1nF
RESPIRATI ON RATE = 10 RESPPM
RESPAMP = 11
RESPGAIN = 0001 = 1
10997-140
AVDD = 3 .3V
ECG PATH/DEFIB/CABLE IMPEDANCE = 1.5kΩ/600pF
PATIENT IMPEDANCE = 1kΩ
Rev. B | Page 22 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Figure 41. DNL Error vs. Input Voltage Range Across Electrodes at 25°C
Figure 42. DNL Error vs. Input Voltage Range Across Temperature
Figure 43. INL vs. Input Voltage Across Gain Setting for 2 kHz Data Rate
Figure 44. INL vs. Input Voltage Across Electrode Channel for 2 kHz Data Rate
Figure 45. INL vs. Input Voltage Across Gain Setting for 16 kHz Data Rate
Figure 46. INL vs. Input Voltage Across Gain Setting for 128 kHz Data Rate
–50
–20
–30
–40
–10
0
20
10
30
40
50
0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3
INPUT VOLTAGE (V)
DNL ERRO R ( µV RTI)
AVDD = 3. 3V LA
LL
RA
10997-070
–50
–20
–30
–40
–10
0
20
10
30
40
50
0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3
INPUT VOLTAGE (V)
DNL ERRO R ( µV RTI)
AVDD = 3. 3V –40°C
–5°C
+25°C
+55°C
+85°C
10997-071
–150
–100
–50
0
50
100
150
0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3
INPUT VOLTAGE (V)
INL (µV/RTI)
GAI N 0
GAI N 1
GAI N 2
GAI N 3
AVDD = 3. 3V
10997-073
–150
–100
–50
0
50
100
150
0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3
INPUT VOLTAGE (V)
INL (µV/RTI)
AVDD = 3. 3V LA
LL
RA
10997-074
–100
–50
0
50
100
150
0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3
INPUT VOLTAGE (V)
INL (µV/RTI)
AVDD = 3. 3V GAI N 0
GAI N 1
GAI N 2
GAI N 3
10997-075
–150
–100
–50
0
50
100
150
0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3
INPUT VOLTAGE (V)
INL (µV/RTI)
AVDD = 3. 3V G AIN 0
GAI N 1
GAI N 2
GAI N 3
10997-076
Rev. B | Page 23 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 24 of 80
Figure 47. FFT with 60 Hz Input Signal
Figure 48. SNR and THD Across Gain Settings
Figure 49. Power Up AVDD Line to ADRDYE
A Going Low (Ready)
Figure 50. Open-Loop Gain Response of Right Leg Drive Amplifier Without
Loading
Figure 51. Open-Loop Phase Response of Right Leg Drive Amplifier Without
Loading
–180
–160
–140
–120
–100
–80
–60
–40
–20
0
0 50 100 150 200 250 300 350 400 450 500
AMPLITUDE (dBFS)
FREQUENCY (Hz)
AVDD = 3.3V
GAIN 0
DATA RA TE = 2 kH z
FILTER SETTING = 150Hz
10997-077
–100
–50
0
50
100
150
GAIN 0 GAIN 1 G A IN 2 G AIN 3
AMPLI T UDE (d B)
GAIN SETTING
SNR
THD
AVDD = 3.3V
–0.5dBFS
10Hz INPUT SIGNAL
10997-078
CH1 2.00V M1.00ms A CH1 2.48V
T22.1%
CH2 1.00V
2
1
DRDY
AVDD = 3.3V
AVDD
10997-079
10997-080
120
LOOP GAIN (dB)
100
80
60
40
20
0
–20
–40
–60
–80
FREQUENCY (Hz)
100m 1 10 100 1k 1G10k 100k 1M 10M 100M
10997-081
0
LOOP GAIN (Phase)
–350
–300
–250
–200
–150
–100
–50
FREQUENCY (Hz)
100m 1 10 100 1k 1G10k 100k 1M 10M 100M
Data Sheet ADAS1000-3/ADAS1000-4
10BAPPLICATIONS INFORMATION
20BOVERVIEW
The ADAS1000-3/ADAS1000-4 are electro cardiac (ECG)
front-end solutions targeted at a variety of medical applica-
tions. In addition to ECG measurements, the ADAS1000-3/
ADAS1000-4 also measure thoracic impedance (respiration)
and detect pacing artifacts, providing all the measured
information to the host controller in the form of a data frame
supplying either lead/vector or electrode data at programmable
data rates. The ADAS1000-3/ADAS1000-4 are designed to
simplify the task of acquiring ECG signals for use in both
monitor and diagnostic applications. Value-added cardiac post
processing may be executed externally on a DSP, microproces-
sor, or FPGA. The ADAS1000-3/ADAS1000-4 are designed for
operation in both low power, portable telemetry applications
and line powered systems; therefore, the parts offer power/noise
scaling to ensure suitability to these varying requirements.
The devices also offer a suite of dc and ac test excitation via
a calibration DAC feature and CRC redundancy checks in
addition to readback of all relevant register address space.
Figure 52. ADAS1000-3 Simplified Block Diagram
COMMON-
MODE AMP
RLD_SJ
DRIVEN
LEAD
AMP SHIELD
DRIVE
AMP
SHIELD
ECG1_LA
ECG2_LL
ECG3_RA
AC
LEAD-OFF
DETECTION
RLD_OUT CM_IN
VREF
REFOUT
XTAL1 XTAL2
PD
CS
SCLK
SDI
DGND
SDO
DRDY
RESET
AGND
IOVDD
CLOCK GE N/O S C/
EXT E RNAL CL K
SOURCE
SYNC_GANG
REFIN CAL_DAC_IO
DC LE AD-
OFF/MUXES
VCM_REF
(1.3V)
CALIBRATION
DAC
CLK_IO
AVDD
ADCVDD
DVDD
GPIO3
GPIO1/MSCLK
GPIO2/MSDO
GPIO0/MCS
AMP
AMP
ECG PATH
VREF
FILTERS,
CONTROL,
AND
INTERFACE
LOGIC
REFGND
CM_OUT/WCT
ADCVDD, DV DD
1.8V
REGULATORS
ADAS1000-3
10kΩ
VCM
ADC
ADC
AMP ADC
AC
LEAD-OFF
DAC
10997-012
Rev. B | Page 25 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 26 of 80
Figure 53. ADAS1000-4 Simplified Block Diagram
–
+
RLD_SJ
DRIVEN
LEAD
AMP SHIELD
DRIVE
AMP
SHIELD
ECG1_LA
ECG2_LL
ECG3_RA
RLD_OUT CM_IN
VREF
REFOUT
XTAL1 XTAL2
PD
CS
SCLK
SDI
DGND
SDO
DRDY
RESET
AGND
IOVDD
CLOCK GEN/OSC/
EXTERNAL CLK
SOURCE
SYNC_GANG
REFIN CAL_DAC_IO
RESPIRATION PATH
EXT_RESP_LA
EXT_RESP_LL
DC LEAD-
OFF/MUXES
VCM_REF
(1.3V)
AC
LEAD-OFF
DAC
RESPIRATION
DAC
CALIBRATION
DAC
CLK_IO
AVDD
ADCVDD
DVDD
GPIO3
GPIO1/MSCLK
GPIO2/MSDO
GPIO0/MCS
AMP
AMP
ECG PATH
VREF
FILTERS,
CONTROL,
AND
INTERFACE
LOGIC
EXT_RESP_R
A
RESPDAC_LA
RESPDAC_LL
RESPDAC_RA
MUX
REFGND
CM_OUT/WCT
ADCVDD, DVDD
1.8V
REGULATORS
ADAS1000-4
10k
Ω
VCM
AMP
ADC
ADC
ADC
AMP
ADC
–
+
AC
LEAD-OFF
DETECTION
PACE
DETECTION
COMMON-
MODE AMP
10997-011
Data Sheet ADAS1000-3/ADAS1000-4
21BECG INPUTS—ELECTRODES/LEADS
The ADAS1000-3/ADAS1000-4 ECG product consists of three
ECG inputs and a reference drive, RLD (right leg drive). In
a typical 3-lead/vector application, three of the ECG inputs
(ECG3_RA, ECG1_LA, ECG2_LL) are used in addition to the
RLD path.
In a 3-lead system, the ADAS1000-3/ADAS1000-4 can be
arranged to provide Lead I, Lead II, and Lead III data or
electrode data directly via the serial interface at all frame
rates. Note that in 128 kHz data rate, lead data is only available
when configured in analog lead mode. Digital lead mode is not
available for this data rate.
Should the user have a need for increased electrode counts, then
there are other products within the ADAS1000 family that may
be suitable. For example, a derived 12-lead (8-electrode) system
can be achieved using one ADAS1000-3 or ADAS1000-4
device ganged together with one ADAS1000-2 slave device
as described in the Gang Mode Operation section. Similarly,
a 12-lead (10-electrode) system can be achieved using one
ADAS1000 or ADAS1000-1 device ganged together with one
ADAS1000-2 slave device as described in the Gang Mode
Operation section. Here, nine ECG electrodes and one RLD
electrode achieve the 10 electrode system, again leaving one
spare ECG channel that could be used for alternate purposes
as suggested previously. In such a system, having nine dedi-
cated electrodes benefits the user by delivering lead information
based on electrode measurements and calculations rather than
deriving leads from other lead measurements.
Table 10 outlines the calculation of the leads (vector) from the
individual electrode measurements when using either the
ADAS1000-3 or ADAS1000-4.
Table 10. Lead Composition
Device Lead Name Composition Equivalent
ADAS1000-3 or ADAS1000-4 I LA – RA
II LL – RA
III LL – LA
aVR1 RA – 0.5 × (LA + LL) −0.5 × (I + II)
aVL1 LA – 0.5 × (LL + RA) 0.5 × (I − III)
aVF1 LL – 0.5 × (LA + RA) 0.5 × (II + III)
1 These augmented leads are not calculated within the ADAS1000-3/ADAS1000-4, but can be derived in the host DSP/microcontroller/FPGA.
Rev. B | Page 27 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 28 of 80
ECG CHANNEL
The ECG channel consists of a programmable gain, low noise,
differential preamplifier; a fixed gain anti-aliasing filter; buffers;
and an ADC (see Figure 54). Each electrode input is routed to
its PGA noninverting input. Internal switches allow the PGA’s
inverting inputs to be connected to other electrodes and/or
the Wilson Central Terminal to provide differential analog
processing (analog lead mode), to a computed average of some
or all electrodes, or to the internal 1.3 V common-mode
reference (VCM_REF). The latter two modes support digital
lead mode (leads computed on-chip) and electrode mode (leads
calculated off-chip). In all cases, the internal reference level is
removed from the final lead data.
The ADAS1000-3/ADAS1000-4 implementation uses a dc-
coupled approach, which requires that the front end be biased
to operate within the limited dynamic range imposed by the
relatively low supply voltage. The right leg drive loop performs
this function by forcing the electrical average of all selected
electrodes to the internal 1.3 V level, VCM_REF, maximizing
each channel’s available signal range.
All ECG channel amplifiers use chopping to minimize 1/f noise
contributions in the ECG band. The chopping frequency of
~250 kHz is well above the bandwidth of any signals of interest.
The 2-pole anti-aliasing filter has ~65 kHz bandwidth to support
digital pace detection while still providing greater than 80 dB
of attenuation at the ADC’s sample rate. The ADC is a 14-bit,
2 MHz SAR converter; 1024 × oversampling helps achieve the
required system performance. The ADC’s full-scale input range
is 2 × VREF, or 3.6 V, although the analog portion of the ECG
channel limits the useful signal swing to about 2.8 V. The
ADAS1000 contains flags to indicate whether the ADC data is
out of range, indicating a hard electrode off state. Programmable
overrange and underrange thresholds are shown in the LOFFUTH
and LOFFLTH registers (see Table 39 and Table 40, respectively).
The ADC out of range flag is contained in the header word (see
Table 53).
Figure 54. Simplified Schematic of a Single ECG Channel
ADC
fS
14
TO COMMON-MODE AMPLIFI ER
FOR DRI V EN L EG AND
SHIELD DRIVER
SHIELD DRIVER
AVDD VREF
ELECTRODE
PREAMP
G = 1, 1 .5, 2, 3
FILTER
DIFF AMP
BUFFER
G = 1.4
PATIENT
CABLE EXTERNAL
RFI AND DE FI B
PROTECTION
VCM
+
–
ELECTRODE
ELECTRODE EXTERNAL
RFI AND DE FI B
PROTECTION
ADAS1000-3/
ADAS1000-4
10997-014
Data Sheet ADAS1000-3/ADAS1000-4
Rev. B | Page 29 of 80
ELECTRODE/LEAD FORMATION AND INPUT
STAGE CONFIGURATION
The input stage of the ADAS1000-3/ADAS1000-4 can be
arranged in several different manners. The input amplifiers
are differential amplifiers and can be configured to generate
the leads in the analog domain, before the ADCs. In addition
to this, the digital data can be configured to provide either
electrode or lead format under user control as described in
Table 37. This allows maximum flexibility of the input stage
for a variety of applications.
Analog Lead Mode and Calculation
Leads are configured in the analog input stage when CHCONFIG
= 1, as shown in Figure 56. This uses a traditional in-amp
structure where lead formation is performed prior to digitiza-
tion, with WCT created using the common-mode amplifier.
While this results in the inversion of Lead II in the analog
domain, this is digitally corrected so output data have the
proper polarity.
Digital Lead Mode and Calculation
When the ADAS1000-3/ADAS1000-4 are configured for digital
lead mode (see the FRMCTL register, 0x0A[4], Table 37), the
digital core will calculate each lead from the electrode signals.
This is straightforward for Lead I/ Lead II/Lead III. Calculating
V1’ and V2’ requires WCT, which is also computed internally
for this purpose. This mode ignores the common-mode
configuration specified in the CMREFCTL register
(Register 0x05). Digital lead calculation is only available in
2 kHz and 16 kHz data rates (see Figure 57).
Electrode Mode: Single-Ended Input Electrode
Configuration
In this mode, the electrode data are digitized relative to the
common-mode signal, VCM, which can be arranged to be any
combination of the contributing ECG electrodes. Common-
mode generation is controlled by the CMREFCTL register
as described in Table 32 (see Figure 59).
Electrode Mode: Common Electrode A and Common
Electrode B Configurations
In this mode, all electrodes are digitized relative to a common
electrode (CE), for example, RA. Standard leads must be calculated
by post processing the output data of the ADAS1000/
ADAS1000-1/ADAS1000-2 (see Figure 58 and Figure 60).
Figure 55. Electrode and Lead Configurations
MODE COMMENT WORD1 WORD2 WORD3
COMMON ELECTRODE (CE)
LEADS (HERE RA ELECTRODE IS
CONNECTED TO THE CE ELECTRODE
(CM_IN) AND V1 IS ON ECG3 INPUT)
LEAD I
(LA − RA)
LEAD II
(LL − RA)
V1’
(V1 – RA) − (LA − RA) − (LL − RA)
ANALOG LEAD LEAD I
(LA − RA)
LEAD II
(LL − RA)
LEAD III
(LL − LA)
SINGLE-ENDED
INPUT ELECTRODE
RELATIVE TO VCM
LL − VCM
LEADS FORMED
RELATIVE TO A
COMMON
ELECTRODE (CE)
LA − CE LL − CE V1 − CE
LEAD I
(LA − RA)
LEAD II
(LL − RA)
LEAD III
(LL − LA)
SINGLE-ENDED
INPUT, DIGITALLY
CALCULATED LEADS
COMMON
ELECTRODE A
ANALOG LEAD
SINGLE-ENDED
INPUT
ELECTRODE
COMMON
ELECTRODE B
DIGITAL LEAD
0x0A
[4]
1
0x01
[10]
2
0x05
[8]
3
000
1
1
0
0
0
001
1
010
LA − VCM RA − VCM
10997-155
3
1
REGISTER FRMCTL, BIT DATAFMT: 0 = LEAD/VECTOR MODE; 1 = ELECTRODE MODE.
2
REGISTER ECGCTL, BIT CHCONFIG: 0 = SINGLE ENDED INPUT (DIGITAL LEAD MODE OR ELECTRODE MODE); 1 = DIFFERENTIAL INPUT (ANALOG LEAD MODE).
3
REGISTER CMREFCTL, BIT CEREFEN: 0 = CE DISABLED; 1 = CE ENABLED.
ADAS1000-3/ADAS1000-4 Data Sheet
Figure 56. Electrode and Lead Configurations, Analog Lead Mode
Figure 57. Electrode and Lead Configurations, Digital Lead Mode
VCM = WCT = ( LA + LL + RA) /3
COMMON-
MODE AMP
ECG1_LA
ECG2_LL
ECG3_RA
AMP ADC
ADC
ADC
CM_IN
FOR EXAMPLE RACOMMON
EL ECTRO DE CE IN
+
–
CM_OUT/WCT
LEAD I
(LA – RA)
LEAD III
(LL – LA)
LEAD II
(LL –RA)*
*GETS MULITPLED
BY –1 IN DIGITAL
AMP
+
–
AMP
+
–
MODE COMMENT WORD1 WORD2 WORD3
ANALO G LEAD LEAD I
(LA − RA) LEAD II
(LL − RA) LEAD III
(LL − LA)
ANALO G LEAD
0x0A
[4]
1
0x01
[10]
2
0x05
[8]
3
010
1
REGIST ER FRMCTL , BI T DATAF M T : 0 = L EAD/VECT OR M ODE; 1 = ELECT RODE M ODE.
2
REGIST ER ECGCTL , BI T CHCONFIG: 0 = SI NGLE E NDED INPUT (DI GITAL L EAD MO DE OR ELE CTRODE MO DE); 1 = DI F FERE NTIAL INPUT ( ANAL OG L EAD MO DE ) .
3
REGIST ER CMREFCTL , BI T CEREF EN: 0 = CE DI S ABLED; 1 = CE ENABLE D.
10997-156
COMMON-
MODE AMP
AMP ADC
ADC
ADC
CM_IN
FOR EXAMPLE, RACOMMON
ELECTRODE CE IN
+
–
CM_OUT/WCT
AMP
+
–
AMP
+
–
ECG1_LA
ECG 2_LL
ECG3_RA
LE AD I
LA – RA
LE AD I I
LL – RA
LEAD III
LL – LA
VCM = WCT = ( LA + LL + RA) /3
MODE COMMENT WORD1 WORD2 WORD3
LEAD I
(LA − RA)
LEAD I I
(LL − RA)
LEAD I II
(LL − LA)
SINGLE-ENDED
INPUT, DIGITALLY
CALCULATED LE ADS
DIGITAL L EAD
0x0A
[4]10x01
[10]20x05
[8]3
000
1REGIST ER FRMCTL , BI T DATAF M T : 0 = L EAD/VECT OR M ODE; 1 = ELECT RODE M ODE.
2REGIST ER ECGCTL , BI T CHCONFIG: 0 = SI NGLE E NDED INPUT (DI GITAL L EAD MO DE OR ELE CTRODE MO DE); 1 = DI F FERE NTIAL INPUT ( ANAL OG L EAD MO DE ) .
3REGIST ER CMREFCTL , BI T CEREF EN: 0 = CE DI S ABLED; 1 = CE ENABLE D.
10997-157
DIGITAL DOMAIN
CALCULATIONS
Rev. B | Page 30 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Figure 58. Electrode and Lead Configurations, Common Electrode A
Figure 59. Electrode and Lead Configurations, Single-Ended Input Electrode
VCM = RA
COMMON-
MODE AMP
AMP ADC
ADC
ADC
CM_IN = RA COMMON
ELECTRODE CE IN
+
–
CM_OUT/WCT
AMP
+
–
AMP
+
–
ECG1_LA
ECG2_LL
ECG3_RA = V1
MODE COMMENT WORD1 WORD2 WORD3
COMM ON ELE CTRODE (CE)
LEADS ( HERE RAE LECT RODE IS
CONNECT ED T O THECE EL ECT RODE
(CM_IN) AND V3 IS ON ECG 3 INPUT)
LEAD I
(LA − RA)
LEAD I I
(LL − RA)
V3’
(V3 – RA) − (LA − RA) − (LL − RA)
COMMON
ELECTRODE A
0x0A
[4]
1
0x01
[10]
2
0x05
[8]
3
001
10997-158
3
1
REGIST ER FRMCTL , BI T DATAF M T : 0 = L EAD/VECT OR M ODE; 1 = ELECT RODE M ODE.
2
REGIST ER ECGCTL , BI T CHCONFIG: 0 = SI NGLE E NDED INPUT (DI GITAL L EAD MO DE OR ELE CTRODE MO DE); 1 = DI F FERE NTIAL INPUT (ANALOG L EAD MO DE ) .
3
REGIST ER CMREFCTL , BI T CEREF EN: 0 = CE DI S ABLED; 1 = CE ENABLE D.
LEAD I
LEAD II
V1’
DIGITAL DOMAIN
CALCULATIONS
VCM = (LA + LL + RA + V1)/
2 IN THIS CAS E
COMMON-
MODE AMP
AMP ADC
ADC
ADC
CM_IN
FOR EXAMPLE, RACOMMON
ELECTRODE CE IN
+
–
CM_OUT/WCT
LA – VCM
LL – VCM
RA – VCM
VCM COMMON MODE
CAN BE ANY COMBINATION
OF ELECTRODES
AMP
+
–
AMP
+
–
ECG1_LA
ECG 2_LL
ECG3_RA
MODE COMMENT WORD1 WORD2 WORD3
SINGLE-ENDED
INPUT EL ECTRODE
RELATIVE TO VCM
LL − VCMSINGLE-ENDED
INPUT
ELECTRODE
0x0A
[4]
1
0x01
[10]
2
0x05
[8]
3
100
LA − VCM RA − VCM
1
REGIST ER FRMCTL , BI T DATAF M T : 0 = L EAD/VECT OR M ODE; 1 = ELECT RODE M ODE.
2
REGIST ER ECGCTL , BI T CHCONFIG: 0 = SI NGLE E NDED INPUT (DI GITAL L EAD MO DE OR ELE CTRODE MO DE); 1 = DI F FERE NTIAL INPUT ( ANAL OG L EAD MO DE ) .
3
REGIST ER CMREFCTL , BI T CEREF EN: 0 = CE DI S ABLED; 1 = CE ENABLE D.
10997-159
Rev. B | Page 31 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 32 of 80
Figure 60. Electrode and Lead Configurations, Common Electrode B
V
CM = CE =
R
A
COMMON-
MODE AMP
AMP ADC
ADC
ADC
CM_IN = RA
COMMON
ELECTRODE CE IN
+
–
CM_OUT/WCT
LA – RA
LL – RA
V3 – RA
AMP
+
–
AMP
+
–
ECG1_LA
ECG2_LL
ECG3_RA = V3
MODE COMMENT WORD1 WORD2 WORD3
LEADS FORMED
RELATIVE TO A
COMMON
ELECTRODE (CE)
LA − CE LL − CE V1 − CECOMMON
ELECTRODE B
0x0A
[4]
1
0x01
[10]
2
0x05
[8]
3
101
10997-160
1
REGISTER FRMCTL, BIT DATAFMT: 0 = LEAD/VECTOR MODE; 1 = ELECTRODE MODE.
2
REGISTER ECGCTL, BIT CHCONFIG: 0 = SINGLE ENDED INPUT (DIGITAL LEAD MODE OR ELECTRODE MODE); 1 = DIFFERENTIAL IN PUT (ANALOG LEAD MODE).
3
REGISTER CMREFCTL, BIT CEREFEN: 0 = CE DISABLED; 1 = CE ENABLED.
Data Sheet ADAS1000-3/ADAS1000-4
DEFIBRILLATOR PROTECTION
The ADAS1000-3/ADAS1000-4 do not include defibrillation
protection on chip. Any defibrillation protection required by
the application requires external components. Figure 61 and
Figure 62 show examples of external defibrillator protection,
which is required on each ECG channel, in the RLD path, and
in the CM_IN path if using the CE input mode. Note that, in
both cases, the total ECG path resistance is assumed to be 5 kΩ.
The 22 MΩ resistors shown connected to RLD are optional and
used to provide a safe termination voltage for an open ECG
electrode; they may be larger in value. Note that, if using these
resistors, the dc lead-off feature works best with the highest
current setting.
ESIS FILTERING
The ADAS1000-3/ADAS1000-4 do not include electrosurgical
interference suppression (ESIS) protection on chip. Any ESIS
protection required by the application requires external
components.
ECG PATH INPUT MULTIPLEXING
As shown in Figure 63, signal paths for numerous functions are
provided on each ECG channel (except respiration, which only
connects to the ECG1_LA, ECG2_LL, and ECG3_RA pins).
Note that the channel enable switch occurs after the RLD
amplifier connection, thus allowing the RLD to be connected
(redirected into any one of the ECG paths). The CM_IN path is
treated the same as the ECG signals.
Figure 61. Possible Defibrillation Protection on ECG Paths Using Neon Bulbs
Figure 62. Possible Defibrillation Protection on ECG Paths Using Diode Protection
Figure 63. Typical ECG Channel Input Multiplexing
10997-161
ELECTRODE
PATIENT
CABLE 4kΩECG1
500Ω500Ω
ELECTRODE
PATIENT
CABLE 4kΩECG2
RLD
22MΩ
1
22MΩ
1
ARGON/NEON
BULB
ARGON/NEON
BULB
1
OPTIONAL.
SP724
AVDD
SP724
AVDD
500Ω500Ω
ADAS1000-3/
ADAS1000-4
ELECTRODE
PATIENT
CABLE 4.5kΩ
ADAS1000-3/
ADAS1000-4
500Ω
ELECTRODE
PATIENT
CABLE 4.5kΩ 500Ω
RLD
22MΩ
1
22MΩ
1
AVDD
AVDD
1
OPTIONAL.
2
TW O L ITTELFUS E S P 724 CHANNE LS PE R E LECTRODE M AY P ROVIDE
BEST PROTECTION.
SP724
2
SP724
2
ECG1
ECG2
10997-162
ANALOG
LEAD
(RA/LA/LL)
INPUT AMPLIFIER
RLD AMP DCLO
CURRENT
ACLO
CURRENT
11.3pF
RESPIRATION
INPUT CALDAC
CHANNEL
ENABLE
ECG PIN
1.3V V CM _RE F +
–
TO CM
AVERAGING
FRO M CM
AVERAGING
TO
FILTERING
ADAS1000
VCM
MUX FOR LEAD CONFIG,
COMM ON ELECT RODE
+
–
10997-163
Rev. B | Page 33 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 34 of 80
COMMON-MODE SELECTION AND AVERAGING
The common-mode signal can be derived from any combina-
tion of one or more electrode channel inputs, the fixed internal
common-mode voltage reference, VCM_REF, or an external
source connected to the CM_IN pin. One use of the latter
arrangement is in gang mode where the master device creates
the Wilson Central Terminal for the slave device(s). The fixed
reference option is useful when measuring the calibration DAC
test tone signals or while attaching electrodes to the patient,
where it allows a usable signal to be obtained from just two
electrodes.
The flexible common-mode generation allows complete
user control over the contributing channels. It is similar to,
but independent of, circuitry that creates the right leg drive
(RLD) signal. Figure 64 shows a simplified version of the
common-mode block. If the physical connection to each
electrode is buffered, these buffers are omitted for clarity.
There are several restrictions on the use of the switches:
If SW1 is closed, SW7 must be open.
If SW1 is open, at least one electrode switch (SW2 to SW7)
must be closed.
SW7 can be closed only when SW2 to SW6 are open, so
that the 1.3 V VCM_REF is summed in only when all ECG
channels are disconnected.
The CM_OUT output is not intended to supply current or drive
resistive loads, and its accuracy is degraded if it is used to drive
anything other than the slave ADAS1000-2 devices. An external
buffer is required if there is any loading on the CM_OUT pin.
Figure 64. Common-Mode Generation Block
Table 11. Truth Table for Common-Mode Selection
ECGCTL
Address 0x011 CMREFCTL Address 0x052
PWREN DRVCM EXTCM LACM LLCM RACM On Switch Description
0 X X X X X Powered down, paths disconnected
1 X 0 0 0 0 SW7 Internal VCM_REF = 1.3 V is selected
1 0 0 1 0 0 SW2 Internal CM selection: LA contributes to VCM
1 0 0 1 1 0 SW2, SW3 Internal CM selection: LA and LL contribute to VCM
1 0 0 1 1 1 SW2, SW3,
SW4
Internal CM selection: LA, LL, and RA contribute to VCM (WCT)
. . . . . . . .
1 X 1 X X X SW1 External VCM selected
1 See Table 28.
2 See Table 32.
ECG1_LA
ECG2_LL
ECG3_RA
+
–
CM_IN
SW2
VCM_REF = 1.3V
SW3
SW4
SW1
SW7
CM_OUT
VCM
( W H E N S E L ECTED, V CM_ R EF IS
SUMMED I N ON EACH EC CHANNEL)
ADAS1000-3/
ADAS1000-4
10997-021
Data Sheet ADAS1000-3/ADAS1000-4
Rev. B | Page 35 of 80
WILSON CENTRAL TERMINAL (WCT)
The flexibility of the common-mode selection averaging allows
the user to achieve a Wilson Central Terminal voltage from the
ECG1_LA, ECG2_LL, ECG3_RA electrodes.
RIGHT LEG DRIVE/REFERENCE DRIVE
The right leg drive amplifier or reference amplifier is used as
part of a feedback loop to force the patient’s common-mode
voltage close to the internal 1.3 V reference level (VCM_REF)
of the ADAS1000-3/ADAS1000-4. This centers all the electrode
inputs relative to the input span, providing maximum input
dynamic range. It also helps to reject noise and interference
from external sources such as fluorescent lights or other
patient-connected instruments, and absorbs the dc or ac
lead-off currents injected on the ECG electrodes.
The RLD amplifier can be used in a variety of ways as shown
in Figure 65. Its input can be taken from the CM_OUT signal
using an external resistor. Alternatively, some or all of the
electrode signals can be combined using the internal switches.
The dc gain of the RLD amplifier is set by the ratio of the
external feedback resistor (RFB) to the effective input resistor,
which can be set by an external resistor, or alternatively, a
function of the number of selected electrodes as configured in
the CMREFCTL register (see Table 32). In a typical case, using
the internal resistors for RIN, all active electrodes would be used
to derive the right leg drive, resulting in a 2 kΩ effective input
resistor. Achieving a typical dc gain of 40 dB would thus require
a 200 kΩ feedback resistor.
The dynamics and stability of the RLD loop depend on the
chosen dc gain and the resistance and capacitance of the
patient cabling. In general, loop compensation using
external components is required, and must be determined
experimentally for any given instrument design and cable set.
In some cases, adding lead compensation will prove necessary,
while in others lag compensation may be more appropriate. The
RLD amplifier’s summing junction is brought out to a package
pin (RLD_SJ) to facilitate compensation.
The RLD amplifier’s short circuit current capability exceeds
regulatory limits. A patient protection resistor is required to
achieve compliance.
Within the RLD block, there is lead-off comparator circuitry
that monitors the RLD amplifier output to determine whether
the patient feedback loop is closed. An open-loop condition,
typically the result of the right leg electrode (RLD_OUT)
becoming detached, tends to drive the amplifier’s output
low. This type of fault is flagged in the header word (see
Table 53), allowing the system software to take action by
notifying the user, redirecting the reference drive to another
electrode via the internal switches of the ADAS1000-3/
ADAS1000-4, or both. The detection circuitry is local to the
RLD amplifier and remains functional with a redirected
reference drive. Table 32 provides details on reference drive
redirection.
While reference drive redirection may be useful in the event
that the right leg electrode cannot be reattached, some pre-
cautions must be observed. Most important is the need for a
patient protection resistor. Because this is an external resistor,
it does not follow the redirected reference drive; some provision
for continued patient protection is needed external to the
ADAS1000-3/ADAS1000-4. Any additional resistance in the
ECG paths will certainly interfere with respiration measure-
ment and may also result in an increase in noise and decrease
in CMRR.
The RLD amplifier is designed to stably drive a maximum
capacitance of 5 nF based on the gain configuration (see
Figure 65) and assuming a 330 kΩ patient protection resistor.
Figure 65. Right Leg Drive—Possible External Component Configuration
ELECTRODE LA
ELECTRODE LL
ELECTRODE RA
+
–
SW2
CM_IN OR
CM BUFFER OUT
SW3
SW6
SW1
EXTERNALLY SUPPLIED COMPONENTS
TO SET RLD LOOP GAIN CZ
2nF
40kΩ
R
IN
*4MΩ
RFB*
100kΩ
RZ
VCM_REF
(1.3V)
RLD_OUTRLD_SJ
10kΩ
10kΩ
10kΩ
10kΩ
RLD_INT_REDIRECT
CM_OUT/WCT
*EXTERNAL RESISTOR R
IN
IS OPTIONAL. IF DRIVING RLD FROM
THE ELECTRODE PATHS, THEN THE SERIES RESISTANCE WILL
CONTRIBUTE TO THE R
IN
IMPEDANCE. WHERE SW1 TO SW5
ARE CLOSED, R
IN
= 2kΩ. RFB SHOULD BE CHOSEN
ACCORDINGLY FOR DESIRED RLD LOOP GAIN.
ADAS1000-3/
ADAS1000-4
10997-022
ADAS1000-3/ADAS1000-4 Data Sheet
CALIBRATION DAC
Within the ADAS1000-3/ADAS1000-4, there are a number of
calibration features.
The 10-bit calibration DAC can be used to correct channel gain
errors (to ensure channel matching) or to provide several test
tones. The options are as follows:
• DC voltage output (range: 0.3 V to 2.7 V). The DAC
transfer function for dc voltage output is
( )
−
×+ 12
V4.2V3.0 10
code
• 1 mV p-p sine wave of 10 Hz or 150 Hz
• 1 mV 1 Hz square wave
Internal switching allows the calibration DAC signals to be
routed to the input of each ECG channel (see Figure 63).
Alternatively, it can be driven out from the CAL_DAC_IO
pin, enabling measurement and correction for external error
sources in the entire ECG signal chain.
To ensure a successful update of the calibration DAC (see
Table 36), the host controller must issue four additional SCLK
cycles after writing the new calibration DAC register word.
GAIN CALIBRATION
The gain for each ECG channel can be adjusted to correct
for gain mismatches between channels. Factory trimmed
gain correction coefficients are stored in nonvolatile memory
on-chip for GAIN 0, GAIN 1, and GAIN 2; there is no factory
calibration for GAIN 3. The default gain values can be over-
written by user gain correction coefficients, which are stored
in volatile memory and available by addressing the appropriate
gain control registers (see Table 50). The gain calibration applies
to the ECG data available on the standard interface and applies
to all data rates.
LEAD-OFF DETECTION
An ECG system must be able to detect if an electrode is no
longer connected to the patient. The ADAS1000-3/ADAS1000-4
support two methods of lead-off detection, ac lead-off detection
and dc lead-off detection. The two systems are independent and
can be used singly or together under the control of the serial
interface (see Table 29).
A lead-off event sets a flag in the frame header word (see Table 53).
Identification of which electrode is off is available as part of the
data frame or as a register read from the lead-off status register
(Register LOFF, see Table 47). In the case of ac lead-off, infor-
mation about the amplitude of the lead-off signal or signals can
be read back through the serial interface (see Table 51).
In a typical ECG configuration, the electrodes RA, LA, and LL
are used to generate a common mode of Wilson Central Terminal
(WCT). If one of these electrodes is off, this affects the WCT
signal and any lead measurements that it contributes to. As a
result, the ECG measurements on these signals are expected to
degrade. The user has full control over the common-mode
amplifier and can adjust the common-mode configuration to
remove that electrode from the common-mode generation. In
this way, the user can continue to make measurements on the
remaining connected leads.
DC Lead-Off Detection
This method injects a small programmable dc current into each
input electrode. When an electrode is properly connected, the
current flows into the right leg (RLD_OUT) and produces a
minimal voltage shift. If an electrode is off, the current charges
that pin’s capacitance, causing the voltage at the pin to float
positive and create a large voltage change that is detected by
the comparators in each channel. These comparators use fixed,
gain-independent upper and lower threshold voltages of 2.4 V
and 0.2 V, respectively. If the input exceeds either of these levels,
the lead-off flag is raised. The lower threshold is included in the
event that something pulls the electrode down to ground.
The dc lead-off detection current can be programmed via the
serial interface. Typical currents range from 10 nA to 70 nA in
10 nA steps. All input pins (RA, LA, LL, V1, V2, and CM_IN)
use identical dc lead-off detection circuitry.
Detecting if the right-leg electrode has fallen off is necessarily
different as RLD_OUT is a low impedance amplifier output. A
pair of fixed threshold comparators monitor the output voltage
to detect amplifier saturation that would indicate a lead-off
condition. This information is available in the DCLEAD-OFF
register (Register 0x1E) along with the lead-off status of all the
input pins.
The propagation delay for detecting a dc lead-off event depends
on the cable capacitance and the programmed current. It is
approximately
Delay = Voltage × Cable Capacitance/Programmed Current
For example:
Delay = 1.2 V × (200 pF/70 nA) = 3.43 ms
DC Lead-Off and High Gains
Using dc lead-off at high gains can result in failure of the circuit
to flag a lead-off condition. The chopping nature of the input
amplifier stage contributes to this situation. When the electrode
is off, the electrode is pulled up; however, in this gain setting,
the first stage amplifier goes into saturation before the input
signal crosses the DCLO upper threshold, resulting in no lead-
off flag. This affects the gain setting GAIN 3 (4.2) and partially
GAIN 2 (2.8).
Increasing the AVDD voltage raises the voltage at which the input
amplifiers saturate, allowing the off electrode voltage to rise high
enough to trip the DCLO comparator (fixed upper threshold of
2.4 V). The ADAS1000 operates over a voltage range of 3.15 V
to 5.5 V. If using GAIN 2/GAIN 3 and dc lead-off, an increased
AVDD supply voltage (minimum 3.6 V) allows dc lead-off to
flag correctly at higher gains.
Rev. B | Page 36 of 80
Data Sheet ADAS1000-3/ADAS1000-4
AC Lead-Off Detection
The alternative method of sensing if the electrodes are
connected to the patient is based on injecting ac currents into
each channel and measuring the amplitudes of the resulting
voltages. The system uses a fixed carrier frequency at 2.039 kHz,
which is high enough to be removed by the ADAS1000-3/
ADAS1000-4 on-chip digital filters without introducing phase
or amplitude artifacts into the ECG signal.
Figure 66. Simplified AC Lead-Off Configuration
The amplitude of the signal is nominally 2 V p-p and is centered
on 1.3 V relative to the chip AGND level. It is ac-coupled into each
electrode. The polarity of the ac lead-off signal can be configured
on a per-electrode basis through Bits[23:18] of the LOFFCTL
register (see Table 29). All electrodes can be driven in phase, and
some can be driven with reversed polarity to minimize the total
injected ac current. Drive amplitude is also programmable. AC
lead-off detection functions only on the input pins (LA, LL, RA,
and CM_IN) and is not supported for the RLD_OUT pin.
The resulting analog input signal applied to the ECG channels is
I/Q demodulated and amplitude detected. The resulting amplitude
is low pass filtered and sent to the digital threshold detectors.
AC lead-off detection offers user programmable dedicated
upper and lower threshold voltages (see Table 39 and Table 40).
Note that these programmed thresholds voltage vary with the
ECG channel gain. The threshold voltages are not affected by
the current level that is programmed. All active channels use
the same detection thresholds.
A properly connected electrode has a very small signal as the
drive current flows into the right leg (RL), whereas a disconnected
electrode has a larger signal as determined by a capacitive
voltage divider (source and cable capacitance).
If the signal measured is larger than the upper threshold, then
the impedance is high, so a wire is probably off. Selecting the
appropriate threshold setting depends on the particular cable/
electrode/protection scheme, as these parameters are typically
unique for the specific use case. This can take the form of starting
with a high threshold and ratcheting it down until a lead-off is
detected, then increasing the threshold by some safety margin.
This gives simple dynamic thresholding that automatically
compensates for many of the circuit variables.
The lower threshold is added for cases where the only ac lead-off
is in use and for situations where an electrode cable has been off
for a long time. In this case, the dc voltage has saturated to a rail,
or the electrode cable has somehow shorted to a supply. In either
case, there is no ac signal present, yet the electrode may not be
connected. The lower threshold checks for a minimum signal level.
In addition to the lead-off flag, the user can also read back the
resulting voltage measurement available on a per channel basis.
The measured amplitude for each of the individual electrodes is
available in Register 0x31 through Register 0x35 (LOAMxx
registers, see Table 51).
The propagation delay for detecting an ac lead-off event is
<10 ms.
Note that the ac lead-off function is disabled when the
calibration DAC is enabled.
ADC Out of Range
When multiple leads are off, the input amplifiers may run into
saturation. This results in the ADC outputting out of range data
with no carrier to the leads off algorithm. The ac lead-off algorithm
then reports little or no ac amplitude. The ADAS1000 contains
flags to indicate if the ADC data is out of range, indicating a hard
electrode off state. There are programmable overrange and under-
range thresholds that can be seen in the LOFFUTH and LOFFLTH
registers (see Table 39 and Table 40, respectively). The ADC out
of range flag is contained in the header word (see Table 53).
SHIELD DRIVER
The shield drive amplifier is a unity-gain amplifier. Its purpose
is to drive the shield of the ECG cables. For power consumption
purposes, it can be disabled if not in use. Note that, the SHIELD
pin is shared with the respiration pin function, where it can be
muxed to be one of the pins for external capacitor connection.
If the pin is being used for the respiration feature, the shield
function is not available. In this case, if the application requires
a shield drive, an external amplifier connected to the CM_OUT
pin can be used.
RESPIRATION (ADAS1000-4 MODEL ONLY)
The respiration measurement is performed by driving a high
frequency (programmable from 46.5 kHz to 64 kHz) differential
current into two electrodes; the resulting impedance variation
caused by breathing causes the differential voltage to vary at the
respiration rate. The signal is ac-coupled onto the patient. The
acquired signal is AM, with a carrier at the driving frequency
and a shallow modulation envelope at the respiration frequency.
The modulation depth is greatly reduced by the resistance of the
customer-supplied RFI and ESIS protection filters, in addition
to the impedance of the cable and the electrode to skin interface
(see Table 12). The goal is to measure small ohm variation
to sub ohm resolution in the presence of large series resistance.
The circuit itself consists of a respiration DAC that drives the
ac-coupled current at a programmable frequency onto the
chosen pair of electrodes. The resulting variation in voltage
is amplified, filtered, and synchronously demodulated in the
digital domain; what results is a digital signal that represents
the total thoracic or respiration impedance, including cable and
electrode contributions. While it is heavily low-pass filtered
on-chip, the user is required to further process it to extract the
AC LO
DAC
2.039kHz
12.5nA TO
100nA rms
LA LL RA
09660-166
CM
11kΩ11kΩ11kΩ
Rev. B | Page 37 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 38 of 80
envelope and perform the peak detection needed to establish
breathing (or lack thereof).
Respiration measurement is available on one of the leads
(Lead I, Lead II, or Lead III) or on an external path via a
pair of dedicated pins (EXT_RESP_LA, EXT_RESP_RA, or
EXT_RESP_LL). Only one lead measurement can be made
at one time. The respiration measurement path is not suited
for use as additional ECG measurements because the internal
configuration and demodulation do not align with an ECG
measurement. The respiration signal processing path is not
reconfigurable for ECG measurements, as it is specifically
designed for the respiration signal measurement.
Internal Respiration Capacitors
The internal respiration function uses an internal RC network
(5 kΩ/100 pF), and this circuit is capable of 200 mΩ resolution
(with up to 5 kΩ total path and cable impedance). The current
is ac-coupled onto the same pins that the measurement is
sensed back on. Figure 67 shows the measurement on Lead I,
but, similarly, the measurement can be configured to measure
on either Lead II or Lead III. The internal capacitor mode requires
no external capacitors and produces currents of ~64 μA p-p
amplitude when configured for maximum amplitude setting
(±1 V) through the RESPCTRL register (see Table 30).
Table 12. Maximum Allowable Cable and Thoracic Loading
Cable Resistance Cable Capacitance
R < 1 kΩ C < 1200 pF
1 kΩ < R < 2.5 kΩ C < 400 pF
2.5 kΩ < R < 5 kΩ C < 200 pF
RTHORACIC < 2 kΩ
Figure 67. Simplified Respiration Block Diagram
LA CABLE
ECG1_LA
EXT_RESP_LA
ECG2_LL
EXT_RESP_LL
ECG3_RA
EXT_RESP_RA
ADAS1000-4
OVERSAMPLED
5kΩ
5kΩ
100pF
100pF
±1V
±1V
RESPIRATION DAC
DRIVE +
CABLE AND ELECTRODE
IMPEDANCE < 5kΩ
LL CABLE
RA CABLE
FILTER
FILTER
FILTER
LPF
RESPIRATION
MEASURE
RESPIRATION DAC
DRIVE–
HPF
IN-AMP AND
ANTI-ALIASING
MAGNITUDE
AND
PHASE
SAR
ADC
46.5kHz TO
64kHz
46.5kHz TO
64kHz
10997-023
Data Sheet ADAS1000-3/ADAS1000-4
External Respiration Path
The EXT_RESP_xx pins are provided for use either with the
ECG electrode cables or, alternatively, with a dedicated external
sensor independent of the ECG electrode path. Additionally, the
EXT_RESP_xx pins are provided so the user can measure the
respiration signal at the patient side of any input filtering on the
front end. In this case, the user must continue to take precautions
to protect the EXT_RESP_xx pins from any signals applied that
are in excess of the operating voltage range (for example, ESIS
or defibrillator signals).
External Respiration Capacitors
If necessary, the ADAS1000-4 allows the user to connect
external capacitors into the respiration circuit to achieve higher
resolution (<200 mΩ). This level of resolution requires that the
cable impedance be ≤1 kΩ. The diagram in Figure 68 shows the
connections at RESPDAC_xx paths for the extended respiration
configuration. Again, the EXT_RESP_xx paths can be con-
nected at the patient side of any filtering circuit; however, the
user must provide protection for these pins. While this external
capacitor mode requires external components, it can deliver a
larger signal-to-noise ratio. Note again that respiration can be
measured on only one lead (at one time); therefore, only one
pair of external respiration paths (and external capacitors) may
be required.
Figure 68. Respiration Measurement Using External Capacitor
LA CABLE
ECG1_LA
EXT_RESP_LA
ECG2_LL
EXT_RESP_LL
ECG3_RA
EXT_RESP_RA
ADAS1000-4
46.5kHz TO
64kHz
46.5kHz TO
64kHz
OVERSAMPLED
5kΩ
1kΩ
1kΩ
1kΩ
5kΩ
100pF
100pF
RESPDAC_LA
RESPDAC_RA
RESPDAC_LL
1nF TO 10nF
1nF TO 10nF
MUTUALLY
EXCLUSIVE
MUTUALLY
EXCLUSIVE
RESPIRAT IO N DAC
DRIVE +
CABLE AND ELECTRO DE
IMPEDANCE < 1kΩ
LL CABLE
RA CABLE
FILTER
FILTER
FILTER
RESPIRATION
MEASURE
RESPIRAT IO N DAC
DRIVE –
HPF
IN- AM P AND
ANTI-ALIASING
MAGNITUDE
AND
PHASE
SAR
ADC
10997-024
±1V
±1V
LPF
Rev. B | Page 39 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Figure 69. Respiration Using External Capacitor and External Amplifiers
If required, further improvements in respiration performance
may be possible with the use of an instrumentation amplifier
and op amp external to the ADAS1000-4. The instrumentation
amplifier must have sufficiently low noise performance to meet
the target performance levels. This mode uses the external
capacitor mode configuration and is shown in Figure 69. Bit 14
of the RESPCTL register (Table 30) allows the user to bypass
the on-chip amplifier when using an external instrumentation
amplifier.
Respiration Carrier Frequency
The frequency of the respiration carrier is programmable and
can be varied through the RESPCTL register (Address 0x03, see
Table 30). The status of the HP bit in the ECGCTL register also
has an influence on the carrier frequency as shown in Table 13.
Table 13. Control of Respiration Carrier Frequencies
RE SPA LT-
FREQ1
RESPEXT-
SYNC1 HP2
RESP-
FREQ1
Respiration Carrier
Frequency
0 0 1 00 56
0 0 1 01 54
0 0 1 10 52
0 0 1 11 50
0 0 0 00 56
0 0 0 01 54
0 0 0 10 52
0 0 0 11 50
1 X3 1 00 64
1
X
3
1
01
56.9
1 X3 1 10 51.2
1 X3 1 11 46.5
1 X3 0 00 32
1 X3 0 01 28
1 X3 0 10 25.5
1 X3 0 11 23
1 Control bits from RESPCTL (Register 0x03).
2 Control bit from ECGCTL (Register 0x01).
3 X = don’t care.
In applications where an external signal generator is used to
develop a respiration carrier signal, that external signal source
can be synchronized to the internal carrier using the signal
available on GPIO3 when Bit 7, RESPEXTSEL, is enabled in
the respiration control register (see Table 30).
Table 14. Control of Respiration Carrier Frequency
Available on GPIO3
RES PALT-
FREQ1
RESPEXT-
SYNC1 HP2
RESP-
FREQ1
Respiration Carrier
Frequency on GPIO3
0
1
X
3
XX
3
64
1 1 1 00 64
1 1 1 01 56
1 1 1 10 51.2
1 1 1 11 46.5
1 1 0 00 32
1 1 0 01 28
1 1 0 10 25.5
1 1 0 11 23
1 Control bits from RESPCTL (Register 0x03).
2 Control bit from ECGCTL (Register 0x01).
3 X = don’t care.
LA CABLE
50kHz T O
56kHz
46.5kHz TO
64kHz
OVERSAMPLED
1kΩ
10kΩ
10kΩ
10kΩ
10kΩ 1kΩ
100Ω
100Ω
RESPDAC_LA
RESPDAC_RA
1nF TO 10nF
1nF TO 10nF
RESPIRAT IO N DAC
DRIVE + ve
CABLE AND ELECTRO DE
IMPEDANCE < 1kΩ
RA CABLE
RESPIRATION
MEASURE
RESPIRAT IO N DAC
DRIVE – ve
HPF
IN- AM P AND
ANTI-ALIASING
MAGNITUDE
AND
PHASE
SAR
ADC
EXT_RESP_LA
EXT_RESP_RA
REF O UT = 1.8V
0.9V
GAIN
1/2 O F AD8606
1/2 O F AD8606
ADAS1000-4
10997-025
±1V
±1V
LPF
Rev. B | Page 40 of 80
Data Sheet ADAS1000-3/ADAS1000-4
EVALUATING RESPIRATION PERFORMANCE
ECG simulators offer a convenient means of studying the
ADAS1000-3/ADAS1000-4’s performance. While many
simulators offer a variable-resistance respiration capability,
care must be taken when using this feature.
Some simulators use electrically-programmable resistors, often
referred to as digiPOTs, to create the time-varying resistance
to be measured by the respiration function. The capacitances
at the digitPOT's terminals are often unequal and code-
dependent, and these unbalanced capacitances can give rise
to unexpectedly large or small results on different leads for
the same programmed resistance variation. Best results are
obtained with a purpose-built fixture that carefully balances
the capacitance presented to each ECG electrode.
PACING ARTIFACT DETECTION FUNCTION
(ADAS1000-4 ONLY)
The pacing artifact validation function qualifies potential
pacing artifacts and measures the width and amplitude of valid
pulses. These parameters are stored in and available from any of
the pace data registers (Address 0x1A, Address 0x3A to Address
0x3C). This function runs in parallel with the ECG channels.
Digital detection is performed using a state machine operating
on the 128 kHz 16-bit data from the ECG decimation chain.
The main ECG signals are further decimated before appearing
in the 2 kHz output stream so that detected pace signals are not
perfectly time-aligned with fully-filtered ECG data. This time
difference is deterministic and may be compensated for.
The pacing artifact validation function can detect and
measure pacing artifacts with widths from 100 μs to 2 ms
and with amplitudes of <400 μV to >1000 m V. Its filters are
designed to reject heartbeat, noise, and minute ventilation
pulses. The flowchart for the pace detection algorithm is
shown in Figure 71.
The ADAS1000-4 pace algorithm can operate with the ac lead-
off and respiration impedance measurement circuitry enabled.
Once a valid pace has been detected in the assigned leads, the
pace-detected flags appear in the header word (see Table 53) at
the start of the packet of ECG words. These bits indicate that a
pace was qualified. Further information on height and width of
pace is available by reading the contents of Address 0x1A (Register
PACEDATA, see Table 44). This word can be included in the
ECG data packet/frame as dictated by the frame control register
(see Table 37). The data available in the PACEDATA register
is limited to seven bits total for width and height information;
therefore, if more resolution is required on the pace height
and width, this is available by issuing read commands of the
PACExDATA registers (Address 0x3A to Address 0x3C) as
shown in Table 52.
The on-chip filtering contributes some delay to the pace signal
(see the Pace Latency section).
Choice of Leads
Three identical and independent state machines are available
and can be configured to run on up to three of four possible
leads (Lead I, Lead II, Lead III, and aVF) for pacing artifact
detection. Any necessary lead calculations are performed
internally and are independent of EGG channel settings for
output data rate, low-pass filter cutoff, and mode (electrode,
analog lead, common electrode). These calculations take into
account the available front-end configurations as detailed in
Table 15.
The pace detection algorithm searches for pulses by analyzing
samples in the 128 kHz ECG data stream. The algorithm
searches for a leading edge, a peak, and a trailing edge as
defined by values in the PACEEDGETH, PACEAMPTH, and
PACELVLTH registers, along with fixed width qualifiers. The
post-reset default register values can be overwritten via the SPI
bus, and different values can be used for each of the three pace
detection state machines.
Some users may not want to use three pace leads for detection.
In this case, Lead II is the vector of choice, because this lead is
likely to display the best pacing artifact. The other two pace
instances can be disabled if not in use.
The first step in pace detection is to search the data stream for
a valid leading edge. Once a candidate edge has been detected,
the algorithm begins searching for a second, opposite-polarity
edge that meets with pulse width criteria and passes the
(optional) noise filters. Only those pulses meeting all the
criteria are flagged as valid pace pulses. Detection of a valid
pace pulse sets the flag(s) in the frame header register and
stores amplitude and width information in the PACEDATA
register (Address 0x1A; see Table 44). The pace algorithm
looks for a negative or positive pulse
Rev. B | Page 41 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Table 15. Pace Lead Calculation
0x01 [10]1 0x05 [8]2 Configuration
0x04 [8:3]3
00 01 10 11
Lead I
(LA − RA)
Lead II
(LL − RA)
Lead III
(LL − LA)
aVF
(Lead II + Lead III)/2
0 0 Digital leads LA − RA
CH1 − CH3
LL − RA
CH2 − CH3
LL − LA
CH2 − CH1
LL − (LA + RA)/2
CH2 − (CH1 + CH3)/2
0 1 Common
Electrode
Lead A
Lead I
CH1
Lead II
CH2
Lead II
–
Lead I
CH2 − CH1
Lead II − 0.5 × Lead I
CH2 − 0.5 × CH1
1 X Analog leads Lead I
CH1
Lead II
− CH3
Lead III
CH2
Lead II − 0.5 × Lead I − CH3 − 0.5 × CH1
1 Register ECGCTL, Bit CHCONFIG, see Table 28.
2 Register CMREFCTL, Bit CEREFEN, see Table 32.
3 Register PACECTL, Bit PACExSEL [1:0], see Table 31.
Rev. B | Page 42 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Detection Algorithm Overview
The pace pulse amplitude and width varies over a wide range,
while its shape is affected by both the internal filtering arising
from the decimation process and the low pass nature of the
electrodes, cabling, and components used for defibrillation and
ESIS protection. The ADAS1000-4 provides user programmable
variables to optimize the performance of the algorithm within
the ECG system, given all these limiting elements. The default
parameter values are probably not optimal for any particular
system design; experimentation and evaluation are needed to
ensure robust performance.
Figure 70. Typical Pace Signal
The first step in pace detection is to search the data stream for a
valid leading edge. Once a candidate edge is detected, the algorithm
verifies that the signal looks like a pulse and then begins searching
for a second, opposite polarity edge that meets the pulse width
and amplitude criteria and passes the optional noise filters. Only
the pulses meeting all requirements are flagged as valid pace pulses.
Detection of a valid pace pulse sets the flag or flags in the frame
header register and stores amplitude and width information in
the PACEDATA register (Address 0x1A; see Table 34).
The pace algorithm detects pulses of both negative and positive
polarity using a single set of parameters by tracking the slope of
the leading edge and making the necessary adjustments to internal
parameter signs. This frees the user to concentrate on determining
appropriate threshold values based on pulse shape without
concern for pulse polarity.
Figure 71. Overview of Pace Algorithm
The three user controlled parameters for the pace detection
algorithm are Pace Amplitude Threshold (PACEAMPTH), Pace
Level Threshold (PACELVLTH), and Pace Edge Threshold
(PACEEDGETH).
PACEAMPTH
PACE WIDTH
LE ADI NG EDGE
LEADING EDGE STOP
PACELVLTH
PACEEDGETH
RECHARGE
PULSE
PACE
PULSE
10997-027
NO
ENABL E P ACE DE TECTI ON
SELECT LEADS
FLAG PACE DETECTED
TRAILING
EDGE
DETECTED?
START
START P ULSE
WIDTH TIMER
START NOI S E
FILTERS (if enabled)
NOISE FILTER
PASSED?
PULSE WIDTH
> 100µs AND <2ms
UPDATE REGISTERS WITH
WIDTH AND HEIGHT
NO
NO
YES
YES
YES
START PACE DE TECTI ON
ALGORITHM
NO
FIND
LE ADI NG EDGE
A > PACEEDGETH?
YES
NO
FIND
END OF
LE ADI NG EDGE
B < PACELVL
YES
PACE AMPLITUDE
> PACEAMPTH NO
YES
YES
10997-171
Rev. B | Page 43 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Pace Edge Threshold
This programmable level (Address 0x0E, see Table 41) is used to
find a leading edge, signifying the start of a potential pace pulse. A
candidate edge is one in which the leading edge crosses a threshold
PACEEDGETH from the recent baseline. PACEEDGETH can
be assigned any value between 0 and 255. Setting PACEEDGETH
to 0 forces it to the value PACEAMPTH/2 (see the following
equation). Non-zero values give the following:
PACEEDGETH setting =
16
2×
×
GAIN
VREFN
where:
N is the 8-bit programmed PACEEDGETH value (1 ≤ N ≤ 255).
VREF is the ADAS1000-4 reference voltage of 1.8 V.
GAIN is the programmed gain of the ECG channel.
The minimum threshold for ×1.4 gain is 19.6 µV, while the
maximum for the same gain setting is 5.00 mV.
Pace Level Threshold
This programmable level (Address 0x0F, see Table 42) is used to
detect when the leading edge of a candidate pulse ends. In general,
a pace pulse is not perfectly square, and the top, meaning the
portion after the leading edge, may continue to increase slightly
or droop back towards the baseline. PACELVLTH defines an
allowable slope for this portion of the candidate pulse, where
the slope is defined as the change in value over an internally-
fixed interval after the pace edge is qualified.
PACELVLTH is an 8-bit, twos complement number. Positive
values represent movement away from the baseline (pulse
amplitude is still increasing) while negative values represent
droop back towards the baseline.
PACELVLTH setting =
16
2
×
×
GAIN
VREF
N
where:
N is the 8-bit programmed PACELVLTH value (−128 ≤ N ≤ 127).
VREF is the ADAS1000-4 reference voltage of 1.8 V.
GAIN is the programmed gain of the ECG channel.
The minimum value for ×1.4 gain is 9.8 µV, while the maximum
for the same gain setting is 2.50 mV.
An additional qualification step, performed after PACELVLTH
is satisfied, rejects pulses with a leading edge transition time greater
than about 156 µs. This filter improves immunity to motion and
other artifacts and cannot be disabled. Overly aggressive ESIS
filtering causes this filter to disqualify valid pace pulses. In such
cases, increasing the value of PACEEDGETH provides more
robust pace pulse detection. Although counterintuitive, this
change forces a larger initial deviation from the recent baseline
before the pace detection algorithm starts, reducing the time
until PACELVLTH comes into play and shortening the apparent
leading edge transition. Increasing the value of PACEEDGETH
may require a reduction in PACEAMPTH.
Pace Amplitude Threshold
This register (Address 0x07, see Table 34) sets the minimum
valid pace pulse amplitude. PACEAMPTH is an unsigned 8-bit
number. The programmed height is given by:
PACEAMPTH setting =
16
2
2
×
××
GAIN
VREFN
,
where:
N is the 8-bit programmed PACEAMPTH value (1 ≤ N ≤ 255).
VREF is the ADAS1000-4 reference voltage of 1.8 V.
GAIN is the programmed gain of the ECG channel.
The minimum threshold for ×1.4 gain is 19.6 µV, while the
maximum for the same gain setting is 5.00 mV. PACEAMPTH
is typically set to the minimum expected pace amplitude and
must be larger than the value of PACEEDGETH.
The default register setting of N = 0x24 results in 706 μV for a
gain = 1 setting. An initial PACEAMPTH setting between
700 µV and 1 mV provides a good starting point for both
unipolar and biventricular pacing detection. Values below
250 µV are not recommended because they greatly increase
sensitivity to ambient noise from the patient. The amplitude
may need to be adjusted much higher than 1 mV when other
medical devices are connected to the patient.
Pace Validation Filters
A candidate pulse that successfully passes the combined tests of
PACEEDGETH, PACELVLTH, and PACEAMPTH is next passed
through two optional validation filters. These filters are used to
reject sub-threshold pulses such as minute ventilation (MV) pulse
and signals from inductively coupled implantable telemetry
systems. These filters perform different tests of pulse shape
using a number of samples. Both filters are enabled by default;
Filter 1 is controlled by Bit 9 in the PACECTL register (see
Table 31) and Filter 2 is controlled by Bit 10 in the same register.
These filters are not available on a lead by lead basis; if enabled,
they are applied to all leads being used for pace detection.
Pace Width Filter
A candidate pulse that successfully passes the edge, amplitude, and
noise filters is finally checked for width. When this final filter is
enabled, it checks that the candidate pulse is between 100 μs
and 2 ms wide. When a valid pace width is detected, the width
is stored. Disabling this filter affects only the minimum width
(100 µs) determination; the maximum width detection portion
of the filter is always active. This filter is controlled by the
PACECTL register, Bit 11 (see Table 31).
Rev. B | Page 44 of 80
Data Sheet ADAS1000-3/ADAS1000-4
BIVENTRICULAR PACERS
As described previously, the pace algorithm expects the pace
pulse to be less than 2 ms wide. In a pacer where both ventricles
are paced, they can be paced simultaneously. Where they fall
within the width and height limits programmed into the algo-
rithm, a valid pace will be flagged, but only one pace pulse may
be visible.
With the pace width filter enabled, the pace algorithm seeks
pace pulse widths within a 100 μs to 2 ms window. Assuming
that this filter is enabled and in a scenario where two ventricle
pacer pulses fire at slightly different times, resulting in the pulse
showing in the lead as one large, wider pulse, a valid pace is
flagged so long as the total width does not exceed 2 ms.
PACE DETECTION MEASUREMENTS
Design verification of the ADAS1000-4 digital pace algorithm
includes detection of a range of simulated pace signals in
addition to using the ADAS1000-4 and evaluation board with
one pacemaker device connected to various simulated loads
(approximately 200 Ω to over 2 kΩ) and covering the following
four waveform corners.
• Minimum pulse width (100 μs), minimum height (to
<300 μV)
• Minimum pulse width (100 μs), maximum height (up to
1.0 V)
• Maximum pulse width (2 ms), minimum height (to
<300 μV)
• Maximum pulse width (2 ms), maximum height (up to
1.0 V)
These scenarios passed with acceptable results. The use of the
ac lead-off function had no obvious impact on the recorded
pace height, width, or the ability of the pace detection algorithm
to identify a pace pulse. The pace algorithm was also evaluated
with the respiration carrier enabled; again, no differences in the
threshold or pacer detect were noted from the carrier.
While these experiments validate the pace algorithm over a
confined set of circumstances and conditions, they do not
replace end system verification of the pacer algorithm. This
can be performed in only the end system, using the system
manufacturer’s specified cables and validation data set.
EVALUATING PACE DETECTION PERFORMANCE
ECG simulators offer a convenient means of studying the perfor-
mance and ability of the ADAS1000-4 to capture pace signals
over the range of widths and heights defined by the various
regulatory standards. While the pace detection algorithm of the
ADAS1000 is designed to conform to medical instrument
standards (pace widths of 100 μs to 2.00 ms and with
amplitudes of <400 μV to >1000 mV), some simulators put out
signals wider or narrower than called for in the standards. The
pace detection algorithm has been designed to measure a
maximum pace widths of 2 ms with a margin of 0.25 ms to
allow for simulator variations.
PACE WIDTH
The ADAS1000-4 is capable of measuring pace widths of 100 μs
to 2.00 ms. The measured pace width is available through the
PACExDATA registers. These registers have limited resolution.
The minimum pace width is 101.56 μs and the maximum is
2.00 ms. The pace detection algorithm always returns a width
greater than what is measured at the 50% point, ensuring that
the algorithm is capable of measuring a narrow 100 μs pulse. A
valid pulse width of 100 μs is reported as 101.56 μs. Any valid
pace pulses ≥2.00 ms and ≤ 2.25 ms are reported as 2.00 ms.
PACE LATENCY
The pace algorithm always examines 128 kHz, 16-bit ECG data,
regardless of the selected frame rate and ECG filter setting. A
pace pulse is qualified when a valid trailing edge is detected
and is flagged in the next available frame header. Pace and ECG
data is always correctly time-aligned at the 128 kHz frame rate,
but the additional filtering inherent in the slower frame rates
delays the frame's ECG data relative to the pace pulse flag.
These delays are summarized in Table 16 and must be taken
into account to enable correct positioning of the pace event
relative to the ECG data.
There is an inherent one-frame-period uncertainty in the exact
location of the pace trailing edge.
PACE DETECTION VIA SECONDARY SERIAL
INTERFACE
The ADAS1000-3/ADAS1000-4 provide a second serial
interface for users to implement their own pace detection
schemes. This interface is configured as a master interface. It
provides ECG data at the 128 kHz data rate only. The purpose
of this interface is to allow the user to access the ECG data at a
rate sufficient to allow them to run their own pace algorithm,
while maintaining all the filtering and decimation of the ECG
data that the ADAS1000-3/ADAS1000-4 offer on the standard
serial interface (2 kHz and 16 kHz data rates). This dedicated
pace interface uses three of the four GPIO pins, leaving one
GPIO pin available even when the secondary serial interface is
enabled. Note that the on-chip digital calibration to ensure
channel gain matching does not apply to data that is available
on this interface. This interface is discussed in more detail in
the Secondary Serial Interface section.
Rev. B | Page 45 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 46 of 80
FILTERING
Figure 72 shows the ECG digital signal processing. The ADC
sample rate is programmable. In high performance mode, it
is 2.048 MHz; in low power mode, the sampling rate is reduced
to 1.024 MHz. The user can tap off framing data at one of three
data rates, 128 kHz, 16 kHz, or 2 kHz. Note that although the
data-word width is 24 bits for the 2 kHz and 16 kHz data rate,
the usable bits are 19 and 18, respectively.
The amount of decimation depends on the selected data rate,
with more decimation for the lower data rates.
Four selectable low-pass filter corners are available at the 2 kHz
data rate.
Filters are cleared by a reset. Table 16 shows the filter latencies
at the different data rates.
Figure 72. ECG Channel Filter Signal Flow
Table 16. Relationship of ECG Waveform to Pace Indication1, 2, 3
Data Rate Conditions Apparent Delay of ECG Data Relative to Pace Event4
2 kHz 450 Hz ECG bandwidth 0.984 ms
250 Hz ECG bandwidth 1.915 ms
150 Hz ECG bandwidth 2.695 ms
40 Hz ECG bandwidth 7.641 ms
16 kHz 109 μs
128 kHz 0
1 ECG waveform delay is the time required to reach 50% of final value following a step input.
2 Guaranteed by design, not subject to production test.
3 There is an unavoidable residual uncertainty of 8 μs in determining the pace pulse trailing edge.
4 Add 38 μs to obtain the absolute delay for any setting.
2.048MHz
A
DC DAT
A
14-BITS
2.048MHz 128kHz
–3dB AT 13kHz
ACLO
CARRIER
NOTCH
2kHz
AC L E AD-OFF
DETECTION
PACE
DETECTION
128kHz D ATA RATE
16-BIT S WI DE
AVAI LABLE DATA RATE
CHOICE O F 1:
40Hz
150Hz
250Hz
(PROG RAMM ABLE BESS EL)
~7Hz
16kHz DATA RATE
24-BIT S WI DE
18 USABL E BI TS
2kHz DATA RATE
24-BIT S WI DE
19 USABL E BI TS
128kHz
16kHz
–3dB AT 3.5kHz
2kHz
–3dB AT 450Hz
16kHz
CALIBRATION
31.2 5Hz DATA RAT E
24-BIT S WI DE
~22 USAB LE BIT S
10997-028
Data Sheet ADAS1000-3/ADAS1000-4
Rev. B | Page 47 of 80
VOLTAGE REFERENCE
The ADAS1000-3/ADAS1000-4 have a high performance,
low noise, on-chip 1.8 V reference for use in the ADC and
DAC circuits. The REFOUT of one device is intended to
drive the REFIN of the same device. The internal reference
is not intended to drive significant external current; for
optimum performance in gang operation with multiple
devices, each device should use its own internal reference.
An external 1.8 V reference can be used to provide the
required VREF. In such cases, there is an internal buffer
provided for use with external reference. The REFIN pin is a
dynamic load with an average input current of approximately
100 μA per enabled channel, including respiration. When the
internal reference is used, the REFOUT pin requires
decoupling with a 10 μF capacitor with low ESR (0.2 Ω
maximum) in parallel with 0.1 μF capacitor to REFGND,
these capacitors should be placed as close to the device pins
as possible and on the same side of the PCB as the device.
GANG MODE OPERATION
Increasing the number of ECG channels enables the user to
measure an increased number of patient electrodes. Typically
a 12-lead system would require nine electrodes (and one right
leg drive reference electrode), but a derived arrangement is
possible by using just eight electrodes (and one right leg drive
reference electrode). As such, mating a 5-electrode ADAS1000,
ADAS1000-1, or ADAS1000-2 with either a ADAS1000-3 or
ADAS1000-4 device delivers the required eight electrodes.
The approach used is a master slave arrangement, where one
device is designated as master, and any others are designated
as slaves. It is important that multiple devices operate well
together; with this in mind, the pertinent inputs/outputs to
interface between master and slave devices have been made
available.
Note that when using multiple devices, the user must collect
the ECG data directly from each device. If using a traditional
12-lead arrangement where the Vx leads are measured
relative to WCT, the user should configure the master device
in lead mode with the slave device configured for electrode
mode. The LSB size for electrode and lead data differs (see
Table 43 for details).
In gang mode, all devices must be operated in the same
power mode (either high performance or low power) and
the same data rate.
Master/Slave
Any of the ADAS1000, ADAS1000-1, ADAS1000-3, or
ADAS1000-4 can be configured as a master or slave, while
the ADAS1000-2 can only be configured as a slave. A device
is selected as a master or slave using Bit 5, master, in the
ECGCTL register (see Table 28). Gang mode is enabled by
setting Bit 4, gang, in the same register. When a device is
configured as a master, the SYNC_GANG pin is automati-
cally set as an output.
When a device is configured as a slave (ADAS1000-2), the
SYNC_GANG and CLK_IO pins are set as inputs.
Synchronizing Devices
The ganged devices need to share a common clock to ensure
that conversions are synchronized. One approach is to drive
the slave CLK_IO pins from the master CLK_IO pin. Alter-
natively, an external 8.192 MHz clock can be used to drive
the CLK_IO pins of all devices. The CLK_IO powers up high
impedance until configured in gang mode.
In addition, the SYNC_GANG pin is used to synchronize
the start of the ADC conversion across multiple devices. The
SYNC_GANG pin is automatically driven by the master and
is an input to all the slaves. SYNC_GANG is in high
impedance until enabled via gang mode.
When connecting devices in gang mode, the SYNC_GANG
output is triggered once when the master device starts to
convert. Therefore, to ensure that the slave device(s) receive
this synchronization signal, configure the slave device first
for operation and enable conversions, followed by issuing the
conversion signal to the ECGCTL register in the master
device.
Figure 73. Master/Slave Connections in Gang Mode, Using Multiple
Devices
Calibration
The calibration DAC signal from one device (master) can be
output on the CAL_DAC_IO pin and used as the calibration
input for other devices (slaves) when used in the gang mode
of operation. This ensures that they are all being calibrated
using the same signal which results in better matching across
channels. This does not happen automatically in gang mode
but, rather, must be configured via Table 36.
MASTER
SYNC_GANG
CM_OUT
CAL_DAC_IO
CLK_IOCLK_IO
SYNC_GANG
CM_IN
CAL_DAC_IO
SYNC_GANG
CM_IN
SLAVE 0
SLAVE 1
CAL_DAC_IO
CLK_IO
10997-029
ADAS1000-3/ADAS1000-4 Data Sheet
Common Mode
The ADAS1000-3/ADAS1000-4 have a dedicated CM_OUT
pin serving as an output and a CM_IN pin as an input. In
gang mode, the master device determines the common-mode
voltage based on the selected input electrodes. This common-
mode signal (on CM_OUT) can then be used by subsequent
slave devices (applied to CM_IN) as the common-mode
reference. All electrodes within the slave device are then
measured with respect to the CM_IN signal from the master
device. See the CMREFCTL register in Table 32 for more
details on the control via the serial interface. Figure 74 shows
the connections between a master and slave device using
multiple devices.
Right Leg Drive
The right leg drive comes from the master device. If the
internal RLD resistors of the slave device are to contribute
to the RLD loop, tie the RLD_SJ pins of master and slave
together.
Sequencing Devices into Gang Mode
When entering gang mode with multiple devices, both
devices can be configured for operation, but the conver-
sion enable bit (ECGCTL register, Bit 2, Table 28) of the
master device should be set after the conversion enable bit
of the slave device. When the master device conversion
signal is set, the master device generates one edge on its
SYNC_GANG pin. This applies to any slave SYNC_GANG
inputs, allowing the devices to synchronize ADC conversions.
Rev. B | Page 48 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Figure 74. Configuring Multiple Devices to Extend Number of Electrodes/Leads
(This example uses ADAS1000-4 as master and ADAS1000-2 as slave; other arrangements possible.)
Table 17. Some Possible Arrangements for Gang Operation
Master Slave 1 Slave 2 Features Number of Electrodes Number of Leads
ADAS1000 ADAS1000-2 ECG, respiration, pace 10 ECG, CM_IN, RLD 12-lead + spare ADC channel
ADAS1000
ADAS1000-2
ADAS1000-2
ECG, respiration, pace
15 ECG, CM_IN, RLD
15-lead + 3 spare ADC channels
ADAS1000 ADAS1000-3 ECG, respiration, pace 8 ECG, CM_IN, RLD 12-lead (derived leads)
ADAS1000-3 ADAS1000-2 ECG 8 ECG, CM_IN, RLD 12-lead (derived leads)
ADAS1000-4 ADAS1000-2 ECG, respiration, pace 8 ECG, CM_IN, RLD 12-lead (derived leads)
SYNC_GANG
TAKE LEAD
DATA
TAKE
ELECTRODE
DATA
ELECTRODES
×3
VREF
REFOUT
REFIN
CAL_DAC_IO
AMP
AMP
ADC
RESPI RATION PATH
MUXES
AC
LEAD-OFF
DAC
ADC
3 × ECG P ATH FILTERS,
CONTROL,
AND
INTERFACE
LOGIC
PACE
DETECTION CS
SCLK
SDI
SDO
DRDY
LEAD-OFF
DETECTION
COMMON-
MODE AMP
RLD_SJ
DRIVEN
LE AD AM P
SHIELD
DRIVE
AMP
SHIELD
RLD_OUT
CM_IN
XTAL1 XTAL2
IOVDD
CLO CK GEN/ OSC/
EXTERNAL CLK
SOURCE
EXT RESP_LA
EXT RESP LL
VCM_REF
(1.3V)
CLK_IO
AVDD
ADCVDD
DVDD
EXT RESP_RA
CM_OUT/
WCT
AC
LEAD-OFF
DAC
10kΩ
ADCVDD, DV DD
1.8V
REGULATORS
(optional)
(optional)
ADAS1000-4
CAL_DAC_IN
CM_IN
SYNC_GANG
ELECTRODES
×5
AMP
MUXES
ADC
5 × ECG P ATH FILTERS,
CONTROL,
AND
INTERFACE
LOGIC
PACE
DETECTION CS
SCLK
SDI
SDO
DRDY
LEAD-OFF
DETECTION
COMMON-
MODE AMP
RLD_SJ IOVDD
CLO CK GEN/ OSC/
EXTERNAL CLK
SOURCE
VCM_REF
(1.3V)
CLK_IO
AVDD
ADCVDD
DVDD
ADCVDD, DV DD
1.8V
REGULATORS
(optional)
(optional)
ADAS1000-2
SLAVE
CALIBRATION
DAC
RESPIRATION
DAC
VREF
REFOUT
REFIN
10997-030
Rev. B | Page 49 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
INTERFACING IN GANG MODE
As shown in Figure 74, when using multiple devices, the
user must collect the ECG data directly from each device.
The example shown in Figure 75 illustrates one possibility
of how to approach interfacing to a master and slave device.
Note that SCLK, SDO, and SDI are shared here with
individual EE
AA lines. This requires the user to read the data
on both devices twice as fast to ensure that they can capture
all the data to maintain the chosen data rate and ensure they
have the relevant synchronized data. Alternative methods
might use individual controllers for each device or separate
SDO paths.
CS
For some applications, digital isolation is required between
the host and the ADAS1000-3/ADAS1000-4. The example
shown illustrates a means to ensure that the number of lines
requiring isolation is minimized.
Figure 75. One Method of Interfacing to Multiple Devices
MASTER
SCLK
SDI
CS
SDO
DRDY (Optional)
SCLK
SDI
CS2
SDO
CS1
SLAVE
SCLK
SDI
CS
SDO
DRDY (Optional)
MICROCRONTROLLER/
DSP
10997-031
Rev. B | Page 50 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Rev. B | Page 51 of 80
SERIAL INTERFACES
The ADAS1000-3/ADAS1000-4 are controlled via a standard
serial interface allowing configuration of registers and readback
of ECG data. This is an SPI-compatible interface that can
operate at SCLK frequencies up to 40 MHz.
The ADAS1000-3/ADAS1000-4 also provide an optional
secondary serial interface that is capable of providing ECG
data at the 128 kHz data rate for users wishing to apply their
own digital pace detection algorithm. This is a master interface
that operates with an SCLK of 20.48 MHz.
STANDARD SERIAL INTERFACE
The standard serial interface is LVTTL-compatible when oper-
ating from a 2.3 V to 3.6 V IOVDD supply. This is the primary
interface for controlling the ADAS1000-3/ADAS1000-4 reading
and writing registers, and reading frame data containing all the
ECG data-words and other status functions within the device.
The SPI is controlled by the following five pins:
ACSE
A (frame synchronization input). Asserting ACSE
A low
selects the device. When ACSE
A is high, data on the SDI
pin is ignored. If ACSE
A is inactive, the SDO output driver is
disabled so that multiple SPI devices can share a common
SDO pin. The ACSE
A pin can be tied low to reduce the number
of isolated paths required. When ACSE
A is tied low, there is no
frame around the data-words; therefore, the user must be
aware of where they are within the frame. All data-words
with 2 kHz and 16 kHz data rates contain register addresses
at the start of each word within the frame. Users can
resynchronize the interface by holding SDI high for 64
SCLK cycles, followed by a read of any register so that
SDI is brought low for the first bit of the following word.
SDI (serial data input pin). Data on SDI is clocked into the
device on the rising edges of SCLK.
SCLK (clocks data in and out of the device). SCLK should
idle high when ACSE
A is high.
SDO (serial data output pin for data readback). Data is
shifted out on SDO on the falling edges of SCLK. The
SDO output driver is high-Z when ACSE
A is high.
ADRDYE
A (data ready, optional). Data ready when low,
busy when high. Indicates the internal status of the
ADAS1000-3/ADAS1000-4 digital logic. It is driven
high/busy during reset. If data frames are enabled and
the frame buffer is empty, this pin is driven busy/high.
If the frame buffer is full, this pin is driven low/ready.
If data frames are not enabled, this pin is driven low to
indicate that the device is ready to accept register
read/write commands. When reading packet data, the
entire packet must be read to allow the ADRDYE
A return
back high.
Figure 76. Serial Interface
Write Mode
The serial word for a write is 32 bits long, MSB first. The serial
interface works with both a continuous and a burst (gated)
serial clock. The falling edge of ACSE
A starts the write cycle.
Serial data applied to SDI is clocked into the ADAS1000-3/
ADAS1000-4 on rising SCLK edges. At least 32 rising clock
edges must be applied to SCLK to clock in 32 bits of data
before ACSE
A is taken high again. The addressed input register is
updated on the rising edge of ACSE
A. For another serial transfer to
take place, ACSE
A must be taken low again. Register writes are used
to configure the device. Once the device is configured and
enabled for conversions, frame data can be initiated to start
clocking
out ECG data on SDO at the programmed data rate. Normal
operation for the device is to send out frames of ECG data.
Typically, register reads and writes should be needed only
during start-up configuration. However, it is possible to write
new configuration data to the device while in framing mode.
A new write command is accepted within the frame and,
depending on the nature of the command, there may be a
need to flush out the internal filters (wait periods) before
seeing usable framing data again.
Write/Read Data Format
Address, data, and the read/write bits are all in the same word.
Data is updated on the rising edge of ACSE
A or the first cycle of the
following word. For all write commands to the ADAS1000-3/
ADAS1000-4, the data-word is 32 bits, as shown in Table 18.
Similarly, when using data rates of 2 kHz and 16 kHz, each
word is 32 bits (address bits and data bits).
Table 18. Serial Bit Assignment (Applies to All Register
Writes, 2 kHz and 16 kHz Reads)
B31 [B30:B24] [B23:B0]
ARE
A/W Address Bits[6:0] Data Bits[23:0] (MSB first)
For register reads, data is shifted out during the next word, as
shown in Table 19.
Table 19. Read/Write Data Stream
Digital
Pin Command 1 Command 2 Command 2
SDI Read Address 1 Read Address 2 Write Address 3
SDO Address 1
Read Data 1
Address 2
Read Data 2
MICROCONTROLLER/
DSP
ADAS1000-3/
ADAS1000-4
SCLK
SDI
CS
SDO
DRDY
SCLK
MOSI
CS
MISO
GPIO
10997-033
ADAS1000-3/ADAS1000-4 Data Sheet
In the 128 kHz data rate, all write words are still 32-bit writes
but the read words in the data packet are now 16 bits (upper
16 bits of register). There are no address bits, only data bits.
Register space that is larger than 16 bits spans across 2 ×
16-bit words (for example, pace and respiration).
87BData Frames/Packets
The general data packet structure is shown in Table 18. Data
can be received in two different frame formats. For the 2 kHz
and 16 kHz data rates, a 32-bit data format is used (where the
register address is encapsulated in the upper byte, identifying
the word within the frame) (see Table 22). For the 128 kHz data
rate, words are provided in 16-bit data format (see Table 23).
When the configuration is complete, the user can begin reading
frames by issuing a read command to the frame header register
(see Table 53). The ADAS1000-3/ADAS1000-4 continue to
make frames available until another register address is written
(read or write command). To continue reading frame data,
continue to write all zeros on SDI, which is a write of the
NOP register (Address 0x00). A frame is interrupted only
when another read or write command is issued.
Each frame can be a large amount of data plus status words. AACSEE
AA
can toggle between each word of data within a frame, or it can
be held constantly low during the entire frame.
Reading all the data-words creates a frame containing 10 × 32
bit words when reading at 2 kHz or 16 kHz data rates; similarly,
a frame contains 13 × 16-bit words when reading at 128 kHz.
Additionally any words not required can be excluded from
the frame. To arrange the frame with the words of interest,
configure the appropriate bits in the frame control register (see
Table 37). The complete set of words per frame are 10 × 32-bit
words for the 2 kHz or 16 kHz data rates, or 13 × 16-bit words
at 128 kHz.
Any data not available within the frame can be read between
frames. Reading a register interrupts the frame and requires
the user to issue a new read command of Address 0x40 (see
Table 53) to start framing again.
88BRead Mode
Although the primary reading function within the ADAS1000-3/
ADAS1000-4 is the output of the ECG frame data, the devices
also allow reading of all configuration registers. To read a
register, the user must first address the device with a read
command containing the particular register address. If the
device is already in data framing mode, the read register
command can be interleaved between the frames by issuing a
read register command during the last word of frame data.
Data shifted out during the next word is the register read data.
To return to framing mode, the user must re-enable framing
by issuing a read of the frame header register (Address 0x40)
(see Table 53). This register write can be used to flush out the
register contents from the previous read command.
Table 20. Example of Reading Registers and Frames
SDI ….. NOP Read
Address
N
Read
frames
NOP NOP …..
SDO ….. Frame
data
Frame
CRC
Register
Data N
Frame
header
Frame
data
…..
Regular register reads are always 32 bits long and MSB first.
Serial Clock Rate
The SCLK can be up to 40 MHz, depending on the IOVDD
voltage level as shown in Table 5. The minimum SCLK
frequency is set by the requirement that all frame data be
clocked out before the next frame becomes available.
SCLK (min) = frame_rate × words_per_frame × bits_per_word
The minimum SCLK for the various frame rates is shown in
Table 21.
Table 21. SCLK Clock Frequency vs. Packet Data/Frame Rates
Frame
Rate
Word
Size
Maximum
Words/Frame1
Minimum
SCLK
128 kHz 16 bits 13 words 26.62 MHz
16 kHz 32 bits 10 words 5.12 MHz
2 kHz 32 bits 10 words 640 kHz
1 This is the full set of words that a frame contains. It is programmable and can
be configured to provide only the words of interest. See Table 37.
Table 22. Default 2 kHz and 16 kHz Data Rate: 32-Bit Frame Word Format
Register Header Lead I/LA Lead II/LL Lead III/RA PACE RESPM RESPPH LOFF GPIO CRC
Address 0x40 0x11 0x12 0x13 0x1A 0x1B 0x1C 0x1D 0x06 0x41
Table 23. Default 128 kHz Data Rate: 16-Bit Frame Word Format
Register Header Lead I/LA Lead II/LL Lead III/RA PACE1 PACE2 RESPM1 RESPM2 RESPH1 RESPH2 LOFF GPIO CRC
Address 0x40 0x11 0x12 0x13 0x1A 0x1B 0x1C 0x1D 0x06 0x41
Rev. B | Page 52 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Internal operations are synchronized to the internal master
clock at either 2.048 MHz or 1.024 MHz (ECGCTL[3]: HP = 1
and HP = 0, respectively, see Table 28). Because there is no
guaranteed relationship between the internal clock and the
SPI's SCLK signal, an internal handshaking scheme is used to
ensure safe data transfer between the two clock domains. A full
handshake requires three internal clock cycles and imposes an
upper speed limit on the SCLK frequency when reading frames
with small word counts. This is true for all data frame rates.
SCLK (max) = (1.024 MHz × (1 + HP) × words_per_frame ×
bits_per_word)/3; or 40 MHz, whichever is lower.
Exceeding the maximum SCLK frequency for a particular
operating mode causes erratic behavior in the EE
AA signal
and results in the loss of data.
DRDY
90BData Rate and Skip Mode
Although the standard frame rates available are 2 kHz, 16 kHz,
and 128 kHz, there is also a provision to skip frames to further
reduce the data rate. This can be configured in the frame
control register (see Table 37).
91BData Ready (AA DRDYEE
AA)
The AADRDYEE
AA pin is used to indicate that a frame composed of
decimated data at the selected data rate is available to read. It
is high when busy and low when ready. Send commands only
when the status of AADRDYEE
AA is low or ready. During power-on, the
status of AADRDYEE
AA is high (busy) while the device initializes itself.
When initialization is complete, AADRDYEE
AA goes low and the user
can start configuring the device for operation. When the device
is configured and enabled for conversions by writing to the
conversion bit (CNVEN) in the ECGCTL register, the ADCs
start to convert and the digital interface starts to make data
available, loading them into the buffer when ready. If conver-
sions are enabled and the buffer is empty, the device is not
ready and AADRDYEE
AA goes high. Once the buffer is full, AADRDYEE
AA
goes low to indicate that data is ready to be read out of the
device. If the device is not enabled for conversions, the AADRDYEE
AA
ignores the state of the buffer full status.
When reading packets of data, the entire data packet must be
read; otherwise, AA DRDYEE
AA stays low.
There are three methods of detecting AADRDYEE
AA status.
• AADRDYEE
AA pin. This is an output pin from the ADAS1000-3/
ADAS1000-4 that indicates the device read or busy status.
No data is valid while this pin is high. The AADRDYEE
AA signals
that data is ready to be read by driving low and remaining
low until the entire frame has been read. It is cleared when
the last bit of the last word in the frame is clocked onto
SDO. The use of this pin is optional.
• SDO pin. The user can monitor the voltage level of the
SDO pin by bringing AACSEE
AA low. If SDO is low, data is ready;
if high, busy. This does not require clocking the SCLK
input. (CPHA = CPOL = 1 only).
• One of the first bits of valid data in the header word availa-
ble on SDO is a data ready status bit (see Table 43). Within
the configuration of the ADAS1000-3/ADAS1000-4, the
user can set the header to repeat until the data is ready. See
Bit 6 (RDYRPT) in the frame control register in Table 37.
The host controller must read the entire frame to ensure AADRDYEE
AA
returns low and ready. If the host controller treats the AADRDYEE
AA as
an edge triggered signal and then misses a frame or underruns,
the AADRDYEE
AA remains high because there is still data available to
read. The host controller must treat the AADRDYEE
AA signal as level
triggered, ensuring that whenever it goes low, it generates an
interrupt which can initiate a SPI frame transfer. On completion
of the transfer the AADRDYEE
AA returns high.
92BDetecting Missed Conversion Data
To ensure that the current data is valid, the entire frame must
be read at the selected data rate. If a read of the entire frame
takes longer than the selected data rate allows, the internal
buffer is not loaded with the latest conversion data. The frame
header register (see Table 53) provides four settings to indicate
an overflow of frame data. The settings of Bits[29:28] report
how many frames have been missed since the last valid frame
read. A missed frame may occur as a result of the last read
taking too long. The data in the current frame is valid data,
but it is not the current data. It is the calculation made directly
after the last valid read.
To clear such an overflow, the user must read the entire frame.
Rev. B | Page 53 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 54 of 80
CRC Word
Framed data integrity is provided by CRCs. For the 128 kHz
frame rates, the 16-bit CRC-CCITT polynomial is used. For the
2 kHz and 16 kHz frame rates, the 24-bit CRC polynomial used.
In both cases, the CRC residue is preset to all 1s and inverted
before being transmitted. The CRC parameters are summarized
in Table 24. To verify that data was correctly received, software
should compute a CRC on both the data and the received
checksum. If data and checksum are received correctly, the
resulting CRC residue should equal the check constant shown
in Table 24. Note that data is shifted through the generator
polynomial MSB first, the same order that it is shifted out
serially. The bit and byte order of the CRC that is appended to
the frame is such that the MSB of the CRC is shifted through
the generator polynomial first in the same order as the data so
that the CRC residue XOR’d with the inverted CRC at the end
of the frame is all 1s (which is why the check constant is
identical for all messages). The CRC is based only on the
data that is sent out.
Figure 77. Input Clock
Clocks
The ADAS1000-3/ADAS1000-4 run from an external crystal or
clock input frequency of 8.192 MHz. The external clock input is
provided for use in gang mode so conversions between the two
devices are synchronized. In this mode, the CLK_IO pin is an
output from the master and an input from the slave. To reduce
power, the CLK_IO is disabled when not in gang mode.
All features within the ADAS1000-3/ADAS1000-4 are a
function of the frequency of the externally applied clock. Using
a frequency other than the 8.192 MHz previously noted causes
scaling of the data rates, filter corners, ac leads-off frequency,
respiration frequency, and pace algorithm corners accordingly.
Table 24. CRC Polynomials
Frame Rate CRC Size Polynomial
Polynomial
in Hex Check Constant
2 kHz, 16 kHz 24 bits x24 + x22 + x20 + x19 + x18 + x16 + x14 + x13 + x11 + x10 + x8 + x7 + x6 + x3 + x1 + x0 0x15D6DCB 0x15A0BA
128 kHz 16 bits x16 + x12 + x5 + x0 0x11021 0x1D0F
XTAL1
XTAL2
ADAS1000-3/
ADAS1000-4
CLK_IO
10997-034
Data Sheet ADAS1000-3/ADAS1000-4
48BSECONDARY SERIAL INTERFACE
This second serial interface is an optional interface that
can be used for the user’s own pace detection purposes.
This interface contains ECG data at 128 kHz data rate only.
If using this interface, the ECG data is still available on the
standard interface discussed previously at lower rates with all
the decimation and filtering applied. If this interface is inactive,
it draws no power.
Data is available in 16-bit words, MSB first.
This interface is a master interface, with the ADAS1000-3/
ADAS1000-4 providing the SCLK, AACSEE
AA, SDO. Is it shared
across some of the existing GPIO pins as follows:
• GPIO1/MSCLK
• GPIO0/AAMCSEE
• GPIO2/MSDO
This interface can be enabled via the GPIO register (see
Table 33).
Figure 78. Master SPI Interface for External Pace Detection Purposes
The data format of the frame starts with a header word, three
ECG data-words, two words filled with zeros and completes
with the same CRC word as documented in Table 24 for the
128 kHz rate. All words are 16 bits. MSCLK runs at approxi-
mately 20 MHz and the AAMCSEE
AA function is asserted for the entire
frame with the data available on MSDO on the falling edge of
MSCLK. MSCLK idles high when AAMCSEE
AA is deasserted.
The data format for this interface is fixed and not influenced by
the FRMCTL register settings. All six words are output, even if
the individual channels are not enabled.
The header word consists of four bits of all 1s followed by a 12-
bit sequence counter. This sequence counter increments after
every frame is sent, thereby allowing the user to tell if any
frames have been missed and how many.
ARESETEE
There are two methods of resetting the ADAS1000-3/ADAS1000-4
to power-on default. Bringing the AARESETEE
AA line low or setting
the SWRST bit in the ECGCTL register (Table 28) resets the
contents of all internal registers to their power-on reset state.
The falling edge of the AARESETEE
AA pin initiates the reset
process; AADRDYEE
AA goes high for the duration, returning low when
the AARESETEE
AA process is complete. This sequence takes 1.5 ms
maximum. Do not write to the serial interface while AA DRDYEE
AA is
high handling a AARESETEE
AA command. When AADRDYEE
AA returns low,
normal operation resumes and the status of the AARESETEE
AA pin is
ignored until it goes low again. Software reset using the SWRST
bit (see Table 28) requires that a NOP (no operation) command
be issued to complete the reset cycle.
APDEE
AA FUNCTION
The AAPDEE
AA pin powers down all functions in low power mode.
The digital registers maintain their contents. The power-down
function is also available via the serial interface (ECG control
register, see Table 28).
Table 25. Master SPI Frame Format; All Words are 16 Bits
Mode\Word 1 2 3 4 5 6 7
Electrode mode1 Header ECG1_LA ECG2_LL ECG3_RA All 0’s All 0’s CRC
Analog lead mode1 Header LEAD I LEAD III −LEAD II (RA-LL) All 0’s All 0’s CRC
1 As set by the FRMCTL register data DATAFMT, Bit [4], see Table 37.
ADAS1000-4
MASTER SPI
SCLK
CS MCS/GPIO0
MICROCONTROLLER/
DSP
MSDO/GPIO2MISO/GPIO
MSCLK/GPIO1
10997-035
Rev. B | Page 55 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 56 of 80
SPI OUTPUT FRAME STRUCTURE (ECG AND STATUS DATA)
Three data rates are offered for reading ECG data: low speed 2 kHz/16 kHz rates for electrode/lead data (32-bit words) and a high speed
128 kHz for electrode/lead data (16-bit words).
Figure 79. Output Frame Structure for 2 kHz and 16 kHz Data Rates with SDO Data Configured for Electrode or Lead Data
Figure 80. Output Frame Structure for 128 kHz Data Rate with SDO Data Configured for Electrode Data
(The 128 kHz Data Rate Can Provide Single-Ended Electrode Data or Analog Lead Mode Data Only. Digital Lead Mode Is Not Available at 128 kHz Data Rate.)
CS
1
SCLK
SDO
2
DRDY
1
CS MAY BE USED I N ONE OF THE FO LL O W ING W AYS:
A) HELD LOW ALL THE TIME.
B) US E D TO FRAME T HE E N TI RE PACKE T OF DATA.
C) US E D TO FRAME EACH INDI VID UAL 32- BIT WO R D.
2
FULL W O RD COUNT = 10 (RESPIRATION PHASE EXCLUDED HERE). WO RDS MAY BE EXCLUDED, SEE THE FRMCTL REGISTER.
32-BIT
DATA W ORDS
2 65473
PACE DETECTION
LEAD III/RA
LEAD I/LA
LEAD II/LL
1
HEADER
RESPIRATION
MAGNITUDE
GPIO
98
DRIVEN OUTPUT DATA STREAM
EACH S CLK WOR D IS 32 CLOCK CYCLES
ANOTHER FRAME OF DATA
CRC WORD
LEAD-OFF
10997-036
CS1
SCLK
SDO2
2 65
47
3
RA
LA
LL
1
HEADER
RESPIRATION
MAGNITUDE
DRDY
911108
DRIVEN OUTPUT DATA STREAM
ANOTHER FRAME
EACH S CLK WOR D IS 16 CLOCK CYCLES
16-BIT
DATA WO R DS
PACE
GPIO
CRC WORD
1CS MAY BE USED IN ONE OF T HE F O L LOWI NG WAYS:
A) HELD LOW ALL THE TIME.
B) USED TO FRAME THE ENTIRE PACKET OF DATA.
C) U S ED TO FRAME E ACH INDIVI DU AL 16- B IT WO RD .
2FULL W ORD COUNT = 13 (RESPIRATION PHASE EXCLUDED HERE). W O RDS MAY BE EXCLUDED, SEE THE FRMCTL REGISTER.
LEAD-OFF
10997-037
Data Sheet ADAS1000-3/ADAS1000-4
13BSPI REGISTER DEFINITIONS AND MEMORY MAP
In 2 kHz and 16 kHz data rates, data takes the form of 32-bit words. Bit A6 to Bit A0 serve as word identifiers. Each 32-bit word has
24 bits of data. A third high speed data rate is also offered: 128 kHz with data in the form of 16-bit words (all 16 bits as data).
Table 26. SPI Register Memory Map
AAREE
AA/W
12
1 A[6:0] D[23:0] Register Name Table Register Description Reset Value
R 0x00 XXXXXX NOP NOP (no operation) 0x000000
R/W 0x01 dddddd ECGCTL Table 28 ECG control 0x000000
R/W 0x02 dddddd LOFFCTL Table 29 Lead-off control 0x000000
R/W 0x03 dddddd RESPCTL
Table 30
Respiration control2 0x000000
R/W 0x04 dddddd PACECTL Table 31 Pace detection control 0x000F88
R/W 0x05 dddddd CMREFCTL Table 32 Common-mode, reference, and shield drive control 0xE00000
R/W 0x06 dddddd GPIOCTL Table 33 GPIO control 0x000000
R/W 0x07 dddddd PACEAMPTH Table 34 Pace amplitude threshold2 0x242424
R/W 0x08 dddddd TESTTONE Table 35 Test tone 0x000000
R/W 0x09 dddddd CALDAC Table 36 Calibration DAC 0x002000
R/W 0x0A dddddd FRMCTL Table 37 Frame control 0x079000
R/W 0x0B dddddd FILTCTL Table 38 Filter control 0x000000
R/W 0x0C dddddd LOFFUTH Table 39 AC lead-off upper threshold 0x00FFFF
R/W 0x0D dddddd LOFFLTH Table 40 AC lead-off lower threshold 0x000000
R/W 0x0E dddddd PACEEDGETH Table 41 Pace edge threshold2 0x000000
R/W 0x0F dddddd PACELVLTH Table 42 Pace level threshold2 0x000000
R 0x11 XXXXXX LADATA Table 43 LA or Lead I data 0x000000
R 0x12 XXXXXX LLDATA Table 43 LL or Lead II data 0x000000
R 0x13 XXXXXX RADATA Table 43 RA or Lead III data 0x000000
R 0x1A XXXXXX PACEDATA Table 44 Read pace detection data/status2 0x000000
R 0x1B XXXXXX RESPMAG Table 45 Read respiration data—magnitude2 0x000000
R 0x1C XXXXXX RESPPH Table 46 Read respiration data—phase2 0x000000
R 0x1D XXXXXX LOFF Table 47 Lead-off status 0x000000
R 0x1E XXXXXX DCLEAD-OFF Table 48 DC lead-off 0x000000
R
0x1F
XXXXXX
OPSTAT
Table 49
Operating state
0x000000
R/W 0x21 dddddd CALLA Table 50 User gain calibration LA 0x000000
R/W 0x22 dddddd CALLL Table 50 User gain calibration LL 0x000000
R/W 0x23 dddddd CALRA Table 50 User gain calibration RA 0x000000
R 0x31 dddddd LOAMLA Table 51 Lead-off amplitude for LA 0x000000
R 0x32 dddddd LOAMLL Table 51 Lead-off amplitude for LL 0x000000
R 0x33 dddddd LOAMRA Table 51 Lead-off amplitude for RA 0x000000
R 0x3A dddddd PACE1DATA Table 52 Pace1 width and amplitude2 0x000000
R 0x3B dddddd PACE2DATA Table 52 Pace2 width and amplitude2 0x000000
R 0x3C dddddd PACE3DATA Table 52 Pace3 width and amplitude2 0x000000
R 0x40 dddddd FRAMES
Table 53
Frame header 0x800000
R 0x41 XXXXXX CRC Table 54 Frame CRC 0xFFFFFF
x Other XXXXXX Reserved3 Reserved XXXXXX
1 R/W = register both readable and writable; R = read only.
2 ADAS1000-4 model only, ADAS1000-3 model does not contain these features.
3 Reserved bits in any register are undefined. In some cases, a physical (but unused) memory bit may be present—in other cases not. Do not issue commands to
reserved registers/space. Read operations of unassigned bits are undefined.
Rev. B | Page 57 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
CONTROL REGISTERS DETAILS
For each register address, the default setting is noted in a default column in addition to being noted in the function column by “(default)”;
this format applies throughout the register map.
Table 27. Serial Bit Assignment
B31 [B30:B24] [B23:B0]
EE
AA
/W
R
Address bits
Data bits (MSB first)
Table 28. ECG Control Register (ECGCTL) Address 0x01, Reset Value = 0x000000
AAREE
AA/W Default Bit Name Function
R/W 0 23 LAEN ECG channel enable; shuts down power to the channel; the input becomes high-Z.
0 (default) = disables ECG channel. When disabled, the entire ECG channel is shut down and dissipates
minimal power.
1 = enables ECG channel.
R/W 0 22 LLEN
R/W 0 21 RAEN
R/W 0 [20:11] Reserved Reserved, set to 0.
R/W 0 10 CHCONFIG Setting this bit selects the differential analog front-end (AFE) input. See Figure 56.
0 (default) = single-ended input (digital lead mode or electrode mode).
1 = differential input (analog lead mode).
R/W 00 [9:8] GAIN [1:0] Preamplifier and anti-aliasing filter overall gain.
00 (default) = GAIN 0 = ×1.4.
01 = GAIN 1 = ×2.1.
10 = GAIN 2 = ×2.8.
11 = GAIN 3 = ×4.2 (user gain calibration is required for this gain setting).
R/W 0 7 VREFBUF VREF buffer enable.
0 (default) = disabled.
1 = enabled (when using the internal VREF, VREFBUF must be enabled).
R/W 0 6 CLKEXT Use external clock instead of crystal oscillator. The crystal oscillator is automatically disabled if
configured as a slave in gang mode and the slave device should receive the clock from the master
device.
0 (default) = XTAL is clock source.
1 = CLK_IO is clock source.
R/W 0 5 Master In gang mode, this bit selects the master (SYNC_GANG pin is configured as an output). When in single
channel mode (gang = 0), this bit is ignored.
0 (default) = slave.
1 = master.
R/W 0 4 Gang Enable gang mode. Setting this bit causes CLK_IO and SYNC_GANG to be activated.
0 (default) = single channel mode.
1 = gang mode.
R/W 0 3 HP Selects the noise/power performance. This bit controls the ADC sampling frequency. See the
Specifications section for further details. This bit also affects the respiration carrier frequency as
discussed in the Respiration Carrier Frequency section.
0 (default) = 1 MSPS, low power.
1 = 2 MSPS, high performance/low noise.
R/W 0 2 CNVEN Conversion enable. Setting this bit enables the ADC conversion and filters.
0 (default) = idle.
1 = conversion enable.
R/W 0 1 PWREN Power enable. Clearing this bit powers down the device. All analog blocks are powered down and the
external crystal is disabled. The register contents are retained during power down as long as DVDD is
not removed.
0 (default) = power down.
1 = power enable.
R/W
0
0
SWRST
Software reset. Setting this bit clears all registers to their reset value. This bit automatically clears itself.
The software reset requires a NOP command to complete the reset.
0 (default) = NOP.
1 = reset.
Rev. B | Page 58 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Table 29. Lead-Off Control Register (LOFFCTL) Address 0x02, Reset Value = 0x000000
AAREE
AA/W Default Bit Name Function
R/W 0 23 LAPH AC lead-off phase.
0 (default) = in phase.
1 = 180° out of phase.
R/W 0 22 LLPH
R/W 0 21 RAPH
R/W 0 [20:19] Reserved Reserved, set to 0.
R/W 0 18 CEPH AC lead-off phase.
0 (default) = in phase.
1 = 180° out of phase.
R/W 0 17 LAACLOEN Individual electrode ac lead-off enable. AC lead-off enables are the OR of ACSEL and the
individual ac lead-off channel enables.
0 (default) = ac lead-off disabled.
1 = ac lead-off enabled.
R/W 0 16 LLACLOEN
R/W 0 15 RAACLOEN
R/W 0 [14:13] Reserved Reserved, set to 0.
R/W 0 12 CEACLOEN Individual electrode ac lead-off enable. AC lead-off enables are the OR of ACSEL and the
individual ac lead-off channel enables.
0 (default) = ac lead-off disabled.
1 = ac lead-off enabled.
R/W 0 [11:9] Reserved Reserved, set to 0.
R/W 00 [8:7] ACCURRENT Set current level for ac lead-off.
00 (default) = 12.5 nA rms.
01 = 25 nA rms.
10 = 50 nA rms.
11 = 100 nA rms.
R/W 00 [6:5] Reserved Reserved, set to 0.
R/W 000 [4:2] DCCURRENT Set current level for dc lead-off (active only for ACSEL = 0).
000 (default) = 0 nA.
001 = 10 nA.
010 = 20 nA.
011 = 30 nA.
100 = 40 nA.
101 = 50 nA.
110 = 60 nA.
111 = 70 nA.
R/W 0 1 ACSEL DC or AC (out-of-band) lead-off detection.
ACSEL acts as a global ac lead-off enable for RA, LL, LA, electrodes (CE ac lead-off is not
enabled using ACSEL). AC lead-off enables are the OR of ACSEL and the individual ac lead-off
channel enables.
If LOFFEN = 0, this bit is don’t care.
If LOFFEN = 1,
0 (default) = dc lead-off detection enabled. (Individual ac lead-off can be enabled through
Bits[17:12].)
1 = dc lead-off detection disabled. AC lead-off detection enabled (all electrodes except CE
electrode).
When the calibration DAC is enabled, ac lead-off is disabled.
R/W 0 0 LOFFEN Enable lead-off detection.
0 (default) = lead-off disabled.
1 = lead-off enabled.
Rev. B | Page 59 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Table 30. Respiration Control Register (RESPCTL) Address 0x03, Reset Value = 0x0000001
AAREE
AA/W Default Bit Name Function
[23:17] Reserved
Reserved, set to 0.
R/W 0 16 RESPALTFREQ Setting this bit to 1 makes the respiration waveform on the GPIO3 pin periodic every cycle. Use in
conjunction with RESFREQ to select drive frequency.
0 (default) = periodic every N cycles (default).
1 = periodic every cycle.
R/W 0 15 RESPEXTSYNC Set this bit to 1 to drive the MSB of the respiration DAC out onto the GPIO3 pin. This signal can be
used to synchronize an external generator to the respiration carrier. It is a constant period only
when RESPALTFREQ = 1.
0 (default) = normal GPIO3 function.
1 = MSB of RESPDAC driven onto the GPIO3 pin.
R/W
0
14
RESPEXTAMP
For use with an external instrumentation amplifier with respiration circuit. Bypasses the on-chip
amplifier stage and input directly to the ADC. See Figure 69.
0 (default) = disabled.
1 = enabled.
R/W 0 13 RESPOUT Selects external respiration drive output. RESPDAC_RA is automatically selected when RESPCAP = 1
0 (default) = RESPDAC_LL and RESPDAC_RA.
1 = RESPDAC_LA and RESPDAC_RA.
R/W 0 12 RESPCAP Selects source of respiration capacitors.
0 (default) = use internal capacitors.
1 = use external capacitors.
R/W 0000 [11:8] RESPGAIN [3:0] Respiration in amp gain (saturates at 10).
0000 (default) = ×1 gain.
0001 = ×2 gain.
0010 = ×3 gain.
…
1000 = ×9 gain.
1001 = ×10 gain.
11xx = ×10 gain.
R/W 0 7 RESPEXTSEL Selects between EXT_RESP _LA or EXT_RESP_LL paths. Applies only if the external respiration is
selected in RESPSEL. EXT_RESP_RA is automatically enabled.
0 (default) = EXT_RESP_LL.
1 = EXT_RESP_LA.
R/W 00 [6:5] RESPSEL [1:0] Set leads for respiration measurement.
00 (default) = Lead I.
01 = Lead II.
10 = Lead III.
11 = external respiration path.
R/W 00 [4:3] RESPAMP Set the test tone amplitude for respiration drive signal.
00 (default) = amplitude/8.
01 = amplitude/4.
10 = amplitude/2.
11 = amplitude.
R/W 00 [2:1] RESPFREQ Set frequency for respiration.
RESPFREQ RESPALTFREQ = 0 RESPALTFREQ = 1 (periodic)
00 (default)
56 kHz
64 kHz
01 54 kHz 56.9 kHz
10 52 kHz 51.2 kHz
11 50 kHz 46.5 kHz
R/W 0 0 RESPEN Enable respiration.
0 (default) = respiration disabled.
1 = respiration enabled.
1 ADAS1000-4 model only, ADAS1000-3 model does not contain this feature.
Rev. B | Page 60 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Table 31. Pace Detection Control Register (PACECTL) Address 0x04, Reset Value = 0x000F881
EE
AA/W RDefault Bit Name Function
[23:12] Reserved Reserved, set to 0
R/W 1 11 PACEFI LT W Pace width filter
0 = filter disabled
1 (default) = filter enabled
R/W 1 10 PACETFILT2 Pace Validation Filter 2
0 = filter disabled
1 (default) = filter enabled
R/W 1 9 PACETFILT1 Pace Validation Filter 1
0 = filter disabled
1 (default) = filter enabled
R/W 11 [8:7] PACE3SEL [1:0] Set lead for pace detection measurement
00 = Lead I
01 = Lead II
10 = Lead III
11 = Lead aVF
R/W 00 [6:5] PACE2SEL [1:0]
R/W 01 [4:3] PACE1SEL [1:0]
R/W
0
2
PACE3EN
Enable pace detection algorithm
0 (default) = pace detection disabled
1 = pace detection enabled
R/W 0 1 PACE2EN
R/W 0 0 PACE1EN
1 ADAS1000-4 model only, ADAS1000-3 model does not contain this feature.
Rev. B | Page 61 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Table 32. Common-Mode, Reference, and Shield Drive Control Register (CMREFCTL) Address 0x05, Reset Value = 0xE00000
AAREE
AA/W Default Bit Name Function
R/W 1 23 LACM Common-mode electrode select.
Any combination of the five input electrodes can be used to create the common-mode
signal, VCM. Bits[23:19] are ignored when Bit 2 is selected. Common mode is the average of
the selected electrodes. When a single electrode is selected, common mode is the signal
level of that electrode alone. The common-mode signal can be driven from the internal
VCM_REF (1.3 V) when Bits [23:19] = 0.
0 = does not contribute to the common mode.
1 = contributes to the common mode.
R/W 1 22 LLCM
R/W 1 21 RACM
R/W 0 [20:15] Reserved Reserved, set to 0.
R/W 0 14 LARLD RLD summing junction.
0 (default) = does not contribute to RLD input.
1 = contributes to RLD input.
R/W 0 13 LLRLD
R/W 0 12 RARLD
R/W
0
[11:10]
Reserved
Reserved, set to 0.
R/W 0 9 CERLD RLD summing junction.
0 (default) = does not contribute to RLD input.
1 = contributes to RLD input.
R/W 0 8 CEREFEN Common electrode (CE) reference, see Figure 56.
0 (default) = common electrode disabled.
1 = common electrode enabled.
R/W 0000 [7:4] RLDSEL [3:0] Select electrode for reference drive.
0000 (default) = RLD_OUT.
0001 = LA.
0010 = LL.
0011 = RA.
0100 to 1111 = reserved.
R/W 0 3 DRVCM Common-mode output. When set, the internally derived common-mode signal is driven
out of the common-mode pin. This bit has no effect if an external common mode is
selected.
0 (default) = common mode is not driven out.
1 = common mode is driven out of the external common-mode pin.
R/W 0 2 EXTCM Select the source of common mode (use when operating multiple devices together).
0 (default) = internal common mode selected.
1 = external common mode selected (all the internal common-mode switches are off).
R/W 0 1 RLDSEL Enable right leg drive reference electrode.
0 (default) = disabled.
1 = enabled.
R/W 0 0 SHLDEN Enable shield drive.
0 (default) = shield drive disabled.
1 = shield drive enabled.
Rev. B | Page 62 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Table 33. GPIO Control Register (GPIOCTL) Address 0x06, Reset Value = 0x000000
AAREE
AA/W Default Bit Name Function
0 [23:19] Reserved Reserved, set to 0
R/W
0
18
SPIFW
Frame secondary SPI words with chip select
0 (default) = AAMCSEE
AA asserted for entire frame
1 = AAMCSEE
AA asserted for individual word
R/W 0 17 Reserved Reserved, set to 0
R/W 0 16 SPIEN Secondary SPI enable; SPI interface providing ECG data at 128 kHz data rate for external digital pace
algorithm detection, uses GPIO0, GPIO1, GPIO2 pins
0 (default) = disabled
1 = enabled; the individual control bits for GPIO0, GPIO1, GPIO2 are ignored; GPIO3 is not affected
by SPIEN
R/W 00 [15:14] G3CTL [1:0] State of GPIO3 pin
00 (default) = high impedance
01 = input
10 = output
11 = open drain
R/W 0 13 G3OUT Output value to be written to GPIO3 when the pin is configured as an output or open drain
0 (default) = low value
1 = high value
R 0 12 G3IN Read only; input value read from GPIO3 when the pin is configured as an input
0 (default) = low value
1 = high value
R/W 00 [11:10] G2CTL [1:0] State of GPIO2 pin
00 (default) = high impedance
01 = input
10 = output
11 = open drain
R/W 0 9 G2OUT Output value to be written to GPIO2 when the pin is configured as an output or open drain
0 (default) = low value
1 = high value
R 0 8 G2IN Read only Input value read from GPIO2 when the pin is configured as an input
0 (default) = low value
1 = high value
R/W 00 [7:6] G1CTL [1:0] State of GPIO1 pin
00 (default) = high impedance
01 = input
10 = output
11 = open drain
R/W
0
5
G1OUT
Output value to be written to GPIO1 when the pin is configured as an output or open drain
0 (default) = low value
1 = high value
R 0 4 G1IN Read only; input value read from GPIO1 when the pin is configured as an input
0 (default) = low value
1 = high value
R/W 00 [3:2] G0CTL [1:0] State of the GPIO0 pin
00 (default) = high impedance
01 = input
10 = output
11 = open drain
R/W 0 1 G0OUT Output value to be written to GPIO0 when the pin is configured as an output or open drain
0 (default) = low value
1 = high value
R 0 0 G0IN (Read only) input value read from GPIO0 when the pin is configured as an input
0 (default) = low value
1 = high value
Rev. B | Page 63 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Table 34. Pace Amplitude Threshold Register (PACEAMPTH) Address 0x07, Reset Value = 0x2424241
AAREE
AA/W Default Bit Name Function
R/W
0010 0100
[23:16]
PACE3AMPTH
Pace amplitude threshold
Threshold = N × 2 × VREF/GAIN/216
R/W
0010 0100
[15:8]
PACE2AMPTH
R/W 0010 0100 [7:0] PACE1AMPTH
1 ADAS1000-4 model only, ADAS1000-3 model does not contain these features.
Table 35. Test Tone Register (TESTTONE) Address 0x08, Reset Value = 0x000000
AAREE
AA/W Default Bit Name Function
R/W 0 23 TONLA Tone select
0 (default) = 1.3 V VCM_REF
1 = 1 mV sine wave or square wave for TONINT = 1, no connect for TONINT = 0
R/W 0 22 TONLL
R/W
0
21
TONRA
R/W 0 [20:5] Reserved Reserved, set to 0
R/W 00 [4:3] TONTYPE 00 (default) = 10 Hz sine wave
01 = 150 Hz sine wave
1x = 1 Hz, 1 mV square wave
R/W 0 2 TONINT Test tone internal or external
0 (default) = external test tone; test tone to be sent out through CAL_DAC_IO and
applied externally to enabled channels
1 = internal test tone; disconnects external switches for all ECG channels and
connects the calibration DAC test tone internally to all ECG channels; in gang
mode, the CAL_DAC_IO is connected, and the slave disables the calibration DAC
R/W 0 1 TONOUT Test tone out enable
0 (default) = disconnects test tone from CAL_DAC_IO during internal mode only
1 = connects CAL_DAC_IO to test tone during internal mode
R/W 0 0 TONEN Enables an internal test tone to drive entire signal chain, from preamplifier to SPI
interface; this tone comes from the calibration DAC and goes to the preamplifier
through the internal mux; when TONEN (calibration DAC) is enabled, ac lead-off is
disabled
0 (default) = disable the test tone
1 = enable the 1 mV sine wave test tone (calibration mode has priority)
Rev. B | Page 64 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Table 36. Calibration DAC Register (CALDAC) Address 0x09, Reset Value = 0x0020001
AAREE
AA/W Default Bit Name Function
0
[23:14]
Reserved
Reserved, set to 0.
R/W 1 13 CALCHPEN Calibration chop clock enable. The calibration DAC output (CAL_DAC_IO) can be
chopped to lower 1/f noise. Chopping is performed at 256 kHz.
0 = disabled.
1 (default) = enabled.
R/W 0 12 CALMODEEN Calibration mode enable.
0 (default) = disable calibration mode.
1 = enable calibration mode; connect CAL DAC_IO, begin data acquisition on ECG
channels.
R/W 0 11 CALINT Calibration internal or external.
0 (default) = external calibration to be performed externally by looping CAL_DAC_IO
around into ECG channels.
1 = internal calibration; disconnects external switches for all ECG channels and
connects calibration DAC signal internally to all ECG channels.
R/W 0 10 CALDACEN Enable 10-bit calibration DAC for calibration mode or external use.
0 (default) = disable calibration DAC.
1 = enable calibration DAC. If a master device and not in calibration mode, also
connects the calibration DAC signal out to the CAL_DAC_IO pin for external use. If in
slave mode, the calibration DAC is disabled to allow master to drive the slave
CAL_DAC_IO pin. When the calibration DAC is enabled, ac lead-off is disabled.
R/W 0000000000 [9:0] CALDATA[9:0] Set the calibration DAC value.
1 To ensure successful update of the calibration DAC, the serial interface must issue four additional SCLK cycles after writing the new calibration DAC register word.
Rev. B | Page 65 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Table 37. Frame Control Register (FRMCTL) Address 0x0A, Reset Value = 0x079000
AAREE
AA/W Default Bit Name Function
R/W 0 23 LEAD I/LADIS Include/exclude word from ECG data frame. If the electrode/lead is included in the data-
word and the electrode falls off, the data-word is undefined.
0 (default) = included in frame.
1 = exclude from frame.
R/W 0 22 LEADII/LLDIS
R/W 0 21 LEADIII/RADIS
R/W 1111 [20:15] Reserved Reserved, set to 111111.
R/W 0 14 PACEDIS1 Pace detection.
0 (default) = included in frame.
1 = exclude from frame.
R/W 0 13 RESPMDIS1 Respiration magnitude.
0 (default) = included in frame.
1 = exclude from frame.
R/W 1 12 RESPPHDIS1 Respiration phase.
0 = included in frame.
1 (default) = exclude from frame.
R/W 0 11 LOFFDIS Lead-off status.
0 (default) = included in frame.
1 = exclude from frame.
R/W 0 10 GPIODIS GPIO word disable.
0 (default) = included in frame.
1 = exclude from frame.
R/W 0 9 CRCDIS CRC word disable.
0 (default) = included in frame.
1 = exclude from frame.
R/W 0 8 Reserved Reserved, set to 0.
R/W 0 7 ADIS Automatically excludes PACEDIS[14], RESPMDIS[13], LOFFDIS[11] words if their flags are
not set in the header.
0 (default) = fixed frame format.
1 = autodisable words (words per frame changes).
R/W 0 6 RDYRPT Ready repeat. If this bit is set and the frame header indicates data is not ready, the frame
header is continuously sent until data is ready.
0 (default) = always send entire frame.
1 = repeat frame header until ready.
R/W 0 5 Reserved Reserved, set to 0.
R/W 0 4 DATAFMT Sets the output data format, see Figure 56.
0 (default) = digital lead/vector format (available only in 2 kHz and 16 kHz data rates).
1 = electrode format.
R/W 00 [3:2] SKIP[1:0] Skip interval. This field provides a way to decimate the data.
00 (default) = output every frame.
01 = output every other frame.
1× = output every 4th frame.
R/W 00 [1:0] FRMRATE[1:0] Sets the output data rate.
00 (default) = 2 kHz output data rate.
01 = 16 kHz output data rate.
10 = 128 kHz output data rate (DATAFMT must be set to 1).
11 = 31.25 Hz.
1 ADAS1000-4 model only, ADAS1000-3 model does not contain these features.
Rev. B | Page 66 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Table 38. Filter Control Register (FILTCTL) Address 0x0B, Reset Value = 0x000000
EE
AA/W RDefault Bit Name Function
R/W 0 [23:6] Reserved Reserved, set to 0
R/W 0 5 MN2K 2 kHz notch bypass for SPI master
0 (default) = notch filter bypassed
1 = notch filter present
R/W 0 4 N2KBP 2 kHz notch bypass
0 (default) = notch filter present
1 = notch filter bypassed
R/W 00 [3:2] LPF[1:0] 00 (default) = 40 Hz
01 = 150 Hz
10 = 250 Hz
11 = 450 Hz
R/W 00 [1:0] Reserved Reserved, set to 0
Table 39. AC Lead-Off Upper Threshold Register (LOFFUTH) Address 0x0C, Reset Value = 0x00FFFF
AAREE
AA/W Default Bit Name Function
0 [23:20] Reserved Reserved, set to 0
R/W 0 [19:16] ADCOVER[3:0] ADC overrange threshold
An ADC out-of-range error is flagged if the ADC output is greater than the overrange
threshold; the overrange threshold is offset from the maximum value
Threshold = max_value – ADCOVER[3:0] × 26
0000 = maximum value (disabled)
0001 = max_value − 64
0010 = max_value − 128
…
1111 = max_value − 960
R/W 0xFFFF [15:0] LOFFUTH[15:0] Applies to ac lead-off upper threshold only; lead-off is detected if the output is ≥ N ×
2 × VREF/gain/216
0 = 0 V
Table 40. AC Lead-Off Lower Threshold Register (LOFFLTH) Address 0x0D, Reset Value = 0x000000
AAREE
AA/W Default Bit Name Function
0 [23:20] Reserved Reserved, set to 0
R/W 0 [19:16] ADCUNDR[3:0] ADC underrange threshold
An ADC out-of-range error is flagged if the ADC output is less than the underrange
threshold
Threshold = min_value + ADCUNDR[3:0] × 26
0000 = minimum value (disabled)
0001 = min_value + 64
0010 = min_value + 128
…
1111 = min_value + 960
R/W 0 [15:0] LOFFLTH[15:0] Applies to ac lead-off lower threshold only; lead-off is detected if the output is ≤ N ×
2 × VREF/GAIN/216
0 = 0 V
Rev. B | Page 67 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Table 41. Pace Edge Threshold Register (PACEEDGETH) Address 0x0E, Reset Value = 0x0000001
AAREE
AA/W Default Bit Name Function
R/W 0 [23:16] PACE3EDGTH Pace edge trigger threshold
0 = PACEAMPTH/2
1 = VREF/gain/216
N = N × VREF/gain/216
R/W
0
[15:8]
PACE2EDGTH
R/W 0 [7:0] PACE1EDGTH
1 ADAS1000-4 model only, ADAS1000-3 model does not contain these features.
Table 42. Pace Level Threshold Register (PACELVLTH) Address 0x0F, Reset Value = 0x0000001
EE
AA/W
RDefault Bit Name Function
R/W 0 [23:16] PACE3LVLTH[7:0] Pace level threshold; This is a signed value
−1 = 0xFF = −VREF/gain/216
0 = 0x00 = 0 V
+1 = 0x01 = +VREF/gain/216
N = N × VREF/gain/216
R/W 0 [15:8] PACE2LVLTH[7:0]
R/W 0 [7:0] PACE1LVLTH[7:0]
1 ADAS1000-4 model only, ADAS1000-3 model does not contain these features.
Table 43. Read Electrode/Lead Data Registers (Electrode/Lead) Address 0x11 to 0x13, Reset Value = 0x0000001
EE
AA/W
RDefault Bit Name Function
[31:24] Address [7:0] 0x11: LA or Lead I.
0x12: LL or Lead II.
0x13: RA or Lead III.
R 0 [23:0] ECG data Channel data value. Data left justified (MSB) irrespective of data rate.
The input stage can be configured into different modes (electrode, analog lead, or digital
lead). In electrode mode and analog lead mode, the digital result value is an unsigned
integer.
In digital lead/vector mode, the value is a signed twos complement integer format and has
a 2× range compared to electrode format because it can swing from +VREF to –VREF;
therefore, the LSB size is doubled.
Electrode mode and analog lead mode:
Minimum value (000…) = 0 V
Maximum value (1111….) = VREF/GAIN
LSB = (2 × VREF/GAIN)/(2N– 1)
ECG (voltage) = ECG Data × (2 × VREF/GAIN)/(2N– 1)
Digital lead mode:
Minimum value (1000…) = −(VREF/GAIN)
Maximum value (0111….) = +VREF/GAIN
LSB = (4 × VREF/GAIN)/(2N – 1)
ECG (voltage) = ECG Data × (4 × VREF/GAIN)/(2N – 1)
where N = number of data bits: 16 for 128 kHz data rate or 24 for 2 kHz/16 kHz data rate.
1 If using 128 kHz data rate in frame mode, only the upper 16 bits are sent. If using the 128 kHz data rate in regular read/write mode, all 32 bits are sent.
Rev. B | Page 68 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Table 44. Read Pace Detection Data/Status Register (PACEDATA) Address 0x1A, Reset Value = 0x0000001, 2, 3
AAREE
AA/W Default Bit Name Function
R 0 23 Pace 3 detected Pace 3 detected. This bit is set once a pace pulse is detected. This bit is set on the
trailing edge of the pace pulse.
0 = pace pulse not detected in current frame.
1 = pace pulse detected in this frame.
R 000 [22:20] Pace Channel 3 width This bit is log2 (width) − 1 of the pace pulse.
Width = 2
N + 1
/128 kHz.
R 0000 [19:16] Pace Channel 3 height This bit is the log2 (height) of the pace pulse.
Height = 2N × VREF/gain/216.
R 0 15 Pace 2 detected Pace 2 detected. This bit is set once a pace pulse is detected. This bit is set on the
trailing edge of the pace pulse.
0 = pace pulse not detected in current frame.
1 = pace pulse detected in this frame.
R 000 [14:12] Pace Channel 2 width This bit is log2 (width) − 1 of the pace pulse.
Width = 2N + 1/128 kHz.
R 0000 [11:8] Pace Channel 2 height This bit is the log2 (height) of the pace pulse.
Height = 2N × VREF/gain/216.
R 0 7 Pace 1 detected Pace 1 detected. This bit is set once a pace pulse is detected. This bit is set on the
trailing edge of the pace pulse.
0 = pace pulse not detected in current frame.
1 = pace pulse detected in this frame.
R 000 [6:4] Pace Channel 1 width This bit is log2 (width) − 1 of the pace pulse.
Width = 2N + 1/128 kHz.
R 0000 [3:0] Pace Channel 1 height This bit is the log2 (height) of the pace pulse.
Height = 2N × VREF/gain/216.
1 If using 128 kHz data rate in frame mode, this word is stretched over two 16-bit words. If using the 128 kHz data rate in regular read/write mode, all 32 bits are sent.
2 Log data for width and height is provided here to ensure that it fits in one full 32-bit data-word. As a result, there may be some amount of error in the resulting value.
For more accurate reading, read the 0x3A, 0x3B, 0x3C registers (see Table 52).
3 ADAS1000-4 model only, ADAS1000-3 model does not contain these features.
Table 45. Read Respiration Data—Magnitude Register (RESPMAG) Address 0x1B, Reset Value = 0x0000001, 2
AAREE
AA/W Default Bit Name Function
R 0 [23:0] Respiration Magnitude[23:0] Magnitude of respiration signal. This is an unsigned value.
4 × (VREF/(1.6468 × respiration gain))/(224 – 1).
1 If using 128 kHz data rate in frame mode, this word is stretched over two 16-bit words. If using the 128 kHz data rate in regular read/write mode, all 32 bits are sent.
2 ADAS1000-4 model only, ADAS1000-3 model does not contain these features.
Table 46. Read Respiration Data—Phase Register (RESPPH) Address 0x1C, Reset Value = 0x0000001, 2
AAREE
AA
/W
Default Bit Name Function
R 0 [23:0] Respiration
Phase[23:0]
Phase of respiration signal. Can be interpreted as either signed or unsigned value. If
unsigned, the range is from 0 to 2π. If signed, the range is from – π to +π.
0x000000 = 0.
0x000001 = 2π/224.
0x400000 = π/2.
0x800000 = +π = − π.
0xC00000 = +3π/2 = − π/2.
0xFFFFFF = +2π(1 − 2−24) = −2π/224.
1 This register is not part of framing data, but may be read by issuing a register read command of this address.
2 ADAS1000-4 model only, ADAS1000-3 model does not contain these features.
Rev. B | Page 69 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Table 47. Lead-Off Status Register (LOFF) Address 0x1D, Reset Value = 0x000000
AAREE
AA/W Default Bit Name Function
R 0 23 RLD lead-off
Status
Electrode connection status.
If either dc or ac lead-off is enabled, these bits are the corresponding lead-off status. If
both dc and ac lead-off are enabled, these bits reflect only the ac lead-off status. DC
lead-off is available in the DCLEAD-OFF register (see Table 48).
The common electrodes have only dc lead-off detection.
An ac lead-off signal can be injected into the common electrode, but there is no ADC
input to measure its amplitude. If the common electrode is off, it affects the ac lead-off
amplitude of the other electrodes.
These bits accumulate in the frame buffer and are cleared when the frame buffer is
loaded into the SPI buffer.
0 = electrode is connected.
1 = electrode is disconnected.
22 LA lead-off status
21
LL lead-off status
20 RA lead-off status
13 CELO
R
0
[19:14]
Reserved
Reserved.
R 0 12 LAADCOR ADC out of range error.
These status bits indicate the resulting ADC code is out of range.
These bits accumulate in the frame buffer and are cleared when the frame buffer is
loaded into the SPI buffer.
11 LLADCOR
10 RAADCOR
R 0 [9:0] Reserved Reserved.
Table 48. DC Lead-Off Register (DCLEAD-OFF) Address 0x1E, Reset Value = 0x0000001
AAREE
AA/W Default Bit Name Function
R 0 23 RLD input
overrange
The dc lead-off detection is comparator based and compares to a fixed level. Individual
electrode bits flag indicate if the dc lead-off comparator threshold level has been
exceeded.
0 = electrode < overrange threshold, 2.4 V.
1 = electrode > overrange threshold, 2.4 V.
22 LA input
overrange
21 LL input
overrange
20 RA input
overrange
13 CE input
overrange
R 0 [19:14]
[8:3]
Reserved Reserved.
R 0 12 RLD input
underrange
The dc lead-off detection is comparator based and compares to a fixed level. Individual
electrode bits indicate if the dc lead-off comparator threshold level has been exceeded.
0 = electrode > underrange threshold, 0.2 V.
1 = electrode < underrange threshold, 0.2 V.
11 LA input
underrange
10 LL input
underrange
9 RA input
underrange
2
CE input
underrange
R 0 [1:0] Reserved
1 This register is not part of framing data, but can be read by issuing a register read command of this address.
Rev. B | Page 70 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Table 49. Operating State Register (OPSTAT) Address 0x1F, Reset Value = 0x0000001
AAREE
AA/W Default Bit Name Function
R 0 [23:4] Reserved Reserved.
R 0 3 Internal error Internal digital failure. This is set if an error is detected in the digital core.
R 0 2 Configuration status This bit is set after a reset indicating that the configuration has not been read yet.
Once the configuration is set, this bit is ready.
0 = ready.
1 = busy.
R 0 1 PLL lock PLL lock lost. This bit is set if the internal PLL loses lock after it is enabled and
locked. This bit is cleared once this register is read or the PWREN bit (Address
0x01[1]) is cleared.
0 = PLL locked.
1 = PLL lost lock.
R 0 0 PLL locked status This bit indicates the current state of the PLL locked status.
0 = PLL not locked.
1 = PLL locked.
1 This register is not part of framing data, but can be read by issuing a register read command of this address. This register assists support efforts giving insight into
potential areas of malfunction within a failing device.
Table 50. User Gain Calibration Registers (CALxx) Address 0x21 to Address 0x23, Reset Value = 0x000000
AAREE
AA/W Default Bit Name Function
[31:24] Address [7:0] 0x21: calibration LA.
0x22: calibration LL.
0x23: calibration RA.
R/W 0 23 USRCAL User can choose between default calibration values or user calibration values for GAIN 0,
GAIN 1, GAIN 2.
Note that for GAIN 3, there is no factory calibration.
0 = default calibration values (factory calibration).
1 = user calibration values.
R/W 0 [22:12] Reserved Reserved, set to 0.
R/W 0 [11:0] CALVALUE Gain calibration value.
Result = data × (1 + gain × 2−17).
The value read from this register is the current gain calibration value. If the USRCAL bit is set
to 0, this register returns the default value for the current gain setting.
0x7FF (+2047) = ×1.00000011111111111b.
0x001 (+1) = ×1.00000000000000001b.
0x000 (0) = ×1.00000000000000000b.
0xFFF (−1) = ×0.11111111111111111b.
0x800 (−2048) = ×0.11111100000000000b.
Rev. B | Page 71 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
Table 51. Read AC Lead-Off Amplitude Registers (LOAMxx) Address 0x31 to Address 0x33, Reset Value = 0x0000001
AAREE
AA/W Default Bit Name Function
[31:24] Address [7:0] 0x31: LA ac lead-off amplitude.
0x32: LL ac lead-off amplitude.
0x33: RA ac lead-off amplitude.
R/W 0 [23:16] Reserved Reserved.
R 0 [15:0] LOFFAM Measured amplitude.
When ac lead-off is selected, the data is the average of the rectified 2 kHz band-pass filter
with an update rate of 8 Hz and cutoff frequency at 2 Hz. The output is the amplitude of the
2 kHz signal scaled by 2/π approximately = 0.6 (average of rectified sine wave). To convert to
rms, scale the output by π/(2√2).
Lead-off (unsigned).
Minimum 0x0000 = 0 V.
LSB 0x0001= VREF/GAIN/216.
Maximum 0xFFFF = VREF/GAIN.
RMS = [π/(2√2)] × [(Code × VREF)/(GAIN × 216)]
Peak-to-peak = π × [(Code × VREF)/(GAIN × 216)]
1 This register is not part of framing data, but can be read by issuing a register read command of this address.
Table 52. Pace Width and Amplitude Registers (PACExDATA) Address 0x3A to Address 0x3C, Reset Value = 0x0000001, 2
AAREE
AA/W Default Bit Name Function
[31:24] Address [7:0] 0x3A: PACE1DATA
0x3B: PACE2DATA
0x3C: PACE3DATA
R 0 [23:8] Pace height Measured pace height in signed twos complement value
0 = 0
1 = VREF/gain/216
N = N × VREF/gain/216
R 0 [7:0] Pace width Measured pace width in 128 kHz samples
N: (N + 1)/128 kHz = width
12: (12 + 1)/128 kHz = 101.56 µs (minimum when pace width filter enabled)
255: (255 + 1)/128 kHz = 2.0 ms
Disabling the pace width filter allows the pace measurement system to
return values of N < 12, that is, pulses narrower than 101.56 μs.
1 These registers are not part of framing data but can be read by issuing a register read command of these addresses.
2 ADAS1000-4 model only, ADAS1000-3 model does not contain these features.
Rev. B | Page 72 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Table 53. Frame Header (FRAMES) Address 0x40, Reset Value = 0x8000001
AAREE
AA/W Default Bit Name Function
R 1 31 Marker Header marker, set to 1 for the header.
R 0 30 Ready bit Ready bit indicates if ECG frame data is calculated and ready for reading.
0 = ready, data frame follows.
1 = busy.
R 0 [29:28] Overflow [1:0] Overflow bits indicate that since the last frame read, a number of frames have
been missed. This field saturates at the maximum count. The data in the frame
including this header word is valid but old if the overflow bits are >0.
When using skip mode (FRMCTL register (0x0A), Bits[3:2]), the overflow bit acts as a
flag, where a nonzero value indicates an overflow.
00 = 0 missed.
01 = 1 frame missed.
10 = 2 frames missed.
11 = 3 or more frames missed.
R 0 27 Fault Internal device error detected.
0 = normal operation.
1 = error condition.
R 0 26 Pace 3 detected Pace 3 indicates pacing artifact was qualified at most recent point.
0 = no pacing artifact.
1 = pacing artifact present.
R 0 25 Pace 2 detected Pace 2 indicates pacing artifact was qualified at most recent point.
0 = no pacing artifact.
1 = pacing artifact present.
R 0 24 Pace 1 detected Pace 1 indicates pacing artifact was qualified at most recent point.
0 = no pacing artifact.
1 = pacing artifact present.
R 0 23 Respiration 0 = no new respiration data.
1 = respiration data updated.
R 0 22 Lead-off detected If both dc and ac lead-off are enabled, this bit is the OR of all the ac lead-off detect
flags. If only ac or dc lead-off is enabled, this bit reflects the OR of all dc and ac
lead-off flags.
0 = all leads connected.
1 = one or more lead-off detected.
R 0 21 DC lead-off detected 0 = all leads connected.
1 = one or more lead-off detected.
R 0 20 ADC out of range 0 = ADC within range.
1 = ADC out of range.
0 [19:0] Reserved Reserved.
1 If using 128 kHz data rate in frame mode, only the upper 16 bits are sent. If using the 128 kHz data rate in regular read/write mode, all 32 bits are sent.
Table 54. Frame CRC Register (CRC) Address 0x41, Reset Value = 0xFFFFFF1
AAREE
AA/W Bit Name Function
R [23:0] CRC Cyclic redundancy check
1 The CRC register is a 32-bit word for 2 kHz and 16 kHz data rate and a 16-bit word for 128 kHz rate. See Table 24 for more details.
Rev. B | Page 73 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
50BINTERFACE EXAMPLES
The following examples show register commands required
to configure the ADAS1000-3/ADAS1000-4 devices into
particular modes of operation and to start framing ECG data.
95BExample 1: Initialize the Device for ECG Capture and
Start Streaming Data
1. Write 1 configures the CMREFCTL register for CM =
WCT = (LA + LL + RA)/3; RLD is enabled onto the
RLD_OUT electrode. The shield amplifier is enabled.
2. Write 2 configures the FRMCTL register to output seven
words per frame/packet. The frame/packet of words
consist of the header, three ECG words, pace, respiration
magnitude, and lead-off. The frame is configured to
always send, irrespective of ready status. The device
is in analog lead mode with a data rate of 2 kHz.
3. Write 3 addresses the ECGCTL register, enabling all
channels into a gain of 1.4, low noise mode, and differen-
tial input, which configures the device for analog lead
mode. This register also configures the device as a master,
using the external crystal as the input source to the XTALx
pins. The device is also put into conversion mode in this
write.
4. Write 4 issues the read command to start putting the
converted data out on the SDO pin.
5. Continue to issue SCLK cycles to read the converted data
at the configured packet data rate (2 kHz). The SDI input
should be held low when reading back the conversion
data because any commands issued to the interface during
read of frame/packet are understood to be a change of
configuration data and will stop the ADC conversions
to allow the interface to process the new command.
96BExample 2: Enable Respiration and Stream Conversion
Data (Applies to ADAS1000-4 Only)
1. Write 1 configures the RESPCTL register with a 56 kHz
respiration drive signal, gain = 1, driving out through
the respiration capacitors and measuring on Lead I.
2. Write 2 issues the read command to start putting the
converted data out on the SDO pin.
3. Continue to issue SCLK cycles to read the converted data
at the configured packet data rate.
4. Note that this example assumes that the FRMCTL register
has already been configured such that the respiration
magnitude is available in the data frame, as arranged in
Write 2 of Example 1.
97BExample 3: DC Lead-Off and Stream Conversion Data
1. Write 1 configures the LOFFCTL register with a dc lead-off
enabled for a lead-off current of 50 nA.
2. Write 2 issues the read command to start putting the
converted data out on the SDO pin.
3. Continue to issue SCLK cycles to read the converted
data at the configured packet data rate.
4. Note that this example assumes that the FRMCTL register
has already been configured such that the dc lead-off word
is available in the data frame, as arranged in Write 2 of
Example 1.
Table 55. Example 1: Initialize the Device for ECG Capture and Start Streaming Data
Write Command Register Addressed Read/Write Bit Register Address Data 32-Bit Write Command
Write 1 CMREFCTL 1 000 0101 1110 0000 0000 0000 0000 1011 0x85E0000B
Write 2 FRMCTL 1 000 1010 0001 1111 1001 0110 0000 0000 0x8A1F9600
Write 3 ECGCTL 1 000 0001 1110 0000 0000 0100 1010 1110 0x81E004AE
Write 4 FRAMES 0 100 0000 0000 0000 0000 0000 0000 0000 0x40000000
Table 56. Example 2: Enable Respiration and Stream Conversion Data (Applies to ADAS1000-4 Only)
Write Command Register Addressed Read/Write Bit Register Address Data 32-Bit Write Command
Write 1 RESPCTL 1 000 0011 0000 0000 0010 0000 1001 1001 0x83002099
Write 2 FRAMES 0 100 0000 0000 0000 0000 0000 0000 0000 0x40000000
Table 57. Example 3: Enable DC Lead-Off and Stream Conversion Data
Write Command
Register addressed
Read/Write Bit
Register Address
Data
32-Bit Write Command
Write 1 LOFFCTL 1 000 0010 0000 0000 0000 0000 0001 0101 0x82000015
Write 2 FRAMES 0 100 0000 0000 0000 0000 0000 0000 0000 0x40000000
Rev. B | Page 74 of 80
Data Sheet ADAS1000-3/ADAS1000-4
98BExample 4: Configure 150 Hz Test Tone Sine Wave on
Each ECG Channel and Stream Conversion Data
1. Write 1 configures the CMREFCTL register to VCM_REF
= 1.3 V (no electrodes contribute to VCM). RLD is enabled
to RLD_OUT, and the shield amplifier enabled.
2. Write 2 addresses the TESTTONE register to enable the
150 Hz sine wave onto all electrode channels.
3. Write 3 addresses the FILTCTL register to change the
internal low-pass filter to 250 Hz to ensure that the 150 Hz
sine wave can pass through.
4. Write 4 configures the FRMCTL register to output nine
words per frame/packet. The frame/packet of words
consists of the header and three ECG words, pace,
respiration magnitude, and lead-off. The frame is
configured to always send, irrespective of ready status.
The device is in electrode format mode with a data rate
of 2 kHz. Electrode format is required to see the test tone
signal correctly on each electrode channel.
5. Write 5 addresses the ECGCTL register, enabling all
channels into a gain of 1.4, low noise mode. It configures
the device as a master and driven from the XTAL input
source. The device is also put into conversion mode
in this write.
6. Write 6 issues the read command to start putting the
converted data out on the SDO pin.
7. Continue to issue SCLK cycles to read the converted data
at the configured packet data rate.
99BExample 5: Enable Pace Detection and Stream
Conversion Data (Applies to ADAS1000-4 Only)
1. Write 1 configures the PACECTL register with all three
pace detection instances enabled, PACE1EN detecting on
Lead II, PACE2EN detecting on Lead I, and PACE3EN
detecting on Lead a V F. T h e pace width filter and validation
filters are also enabled.
2. Write 2 issues the read command to start putting the
converted data out on the SDO pin.
3. Continue to issue SCLK cycles to read the converted data
at the configured packet data rate. When a valid pace is
detected, the detection flags are confirmed in the header
word and the PACEDATA register contains information
on the width and height of the measured pulse from each
measured lead.
4. Note that the PACEAMPTH register default setting is
0x242424, setting the amplitude of each of the pace
instances to 1.98 mV/gain.
5. Note that this example assumes that the FRMCTL register
has already been configured such that the PACEDATA
word is available in the data frame, as arranged in Write 2
of Example 1.
Table 58. Example 4: Configure 150 Hz Test Tone Sine Wave on Each ECG Channel and Stream Conversion Data
Write Command Register Addressed Read/Write Bit Register Address Data 32-Bit Write Command
Write 1 CMREFCTL 1 000 0101 0000 0000 0000 0000 0000 1011 0x8500000B
Write 2 TESTTONE 1 000 1000 1110 0000 0000 0000 0000 1101 0x88E0000D
Write 3 FILTCTL 1 000 1011 0000 0000 0000 0000 0000 1000 0x8B000008
Write 4 FRMCTL 1 000 1010 0001 1111 1001 0110 0001 0000 0x8A1F9610
Write 5 ECGCTL 1 000 0001 1110 0000 0000 0000 1010 1110 0x81E000AE
Write 6 FRAMES 0 100 0000 0000 0000 0000 0000 0000 0000 0x40000000
Table 59. Example 5: Enable Pace Detection and Stream Conversion Data (Applies to ADAS1000-4 Only)
Write Command Register Addressed Read/Write Bit Register Address Data 32-Bit Write Command
Write 1
PACECTL
1
000 0100
0000 0000 0000 1111 1000 1111
0x84000F8F
Write 2 FRAMES 0 100 0000 0000 0000 0000 0000 0000 0000 0x40000000
Rev. B | Page 75 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
100BExample 6: Writing to Master and Slave Devices and Streaming Conversion Data
This example uses the ADAS1000-3 as the slave device and the
ADAS1000 as the master device to achieve a configuration with
eight input electrodes and one right leg drive.
101B101BSlave Configuration (ADAS1000-3)
1. Write 1 configures the FRMCTL register to output five
words per frame/packet. The frame/packet of words
consists of the header, three ECG words, and lead-off. The
frame is configured to always send, irrespective of ready
status. The slave ADAS1000-3 is in electrode mode format
with a data rate of 2 kHz.
2. Write 2 configures the CMREFCTL register to receive an
external common mode from the master.
3. Write 3 addresses the ECGCTL register, enabling all
channels into a gain of 1.4, low noise mode. It configures
the device as a slave, in gang mode and driven from the
CLK_IN input source (derived from master ADAS1000).
The ADAS1000-3 slave is also put into conversion mode
in this write, but waits for the SYNC_GANG signal from
the master device before it starts converting.
102B102BMaster Configuration (ADAS1000)
• Write 4 configures the FRMCTL register to output seven
words per frame/packet (note that this differs from the
number of words in a frame available from the slave
device). The frame/packet of words consists of the header,
five ECG words, pace, respiration magnitude, and lead-off.
In this example, the frame is configured to always send
irrespective of ready status. The master, ADAS1000, is in
vector mode format with a data rate of 2 kHz. Similar
to the slave device, the master could be configured for
electrode mode; the host controller would then be required
to make the lead calculations.
1. Write 5 configures the CMREFCTL register for CM =
WCT = (LA + LL + RA)/3; RLD is enabled onto
RLD_OUT electrode. The shield amplifier is enabled.
The CM = WCT signal is driven out of the master device
(CM_OUT) into the slave device (CM_IN).
2. Write 6 addresses the ECGCTL register, enabling all
channels into a gain of 1.4, low noise mode. It configures
the device as a master in gang mode and driven from
the XTAL input source. The ADAS1000 master is set to
differential input, which places it in analog lead mode.
This ECGCTL register write puts the master into
conversion mode, where the device sends an edge on
the SYNC_GANG pin to the slave device to trigger the
simultaneous conversions of both devices.
3. Write 7 issues the read command to both devices to start
putting the converted and decimated data out on the
respective SDO pins.
4. Continue to issue SCLK cycles to read the converted data
at the configured packet data rate.
Table 60. Example 6: Writing to Master and Slave Devices and Streaming Conversion Data
Device Write Command Register Addressed R/W Register Address Data 32-Bit Write Command
Slave Write 1 FRMCTL 1 000 1010 0001 1111 1111 0110 0001 0000 0x8A1FF610
Write 2 CMREFCTL 1 000 0101 0000 0000 0000 0000 0000 0100 0x85000004
Write 3 ECGCTL 1 000 0001 1110 0000 0000 0000 1101 1110 0x81E000DE
Master Write 4 FRMCTL 1 000 1010 0001 1111 1001 0110 0000 0000 0x8A1F9600
Write 5 CMREFCTL 1 000 0101 1110 0000 0000 0000 0000 1011 0x85E0000B
Write 6 ECGCTL 1 000 0001 1110 0000 0000 0100 1011 1110 0x81E004BE
Master
and
Slave
Write 7 FRAMES 0 100 0000 0000 0000 0000 0000 0000 0000 0x40000000
Rev. B | Page 76 of 80
Data Sheet ADAS1000-3/ADAS1000-4
51BSOFTWARE FLOWCHART
Figure 81 shows a suggested sequence of steps to be taken to interface to multiple devices.
Figure 81. Suggested Software Flowchart for Interfacing to Multiple Devices
IS CRC
CORRECT?
DRDY
LOW?
POWER UP ADAS 1000
DEVICES
ADAS1000 GOES INT O
POWER- DOW N M ODE
WAIT FOR POR ROUTINE
TO COMPLETE, 1.5ms
INITIALIZE SLAVE
DEVICES
INITIALIZE MASTER DEVICE
ENABL I NG CO NV E RS IO N
ISS UE RE AD FRAME
COMMAND (W RIT E TO 0x40)
DISCARD
FRAM E DATA
ISSUE SCLK CYCLES (SDI = 0)
TO CLOCK F RAM E DATA OUT
AT P RO GRAMM E D DATA RAT E
ACTIVITY
ON
SDI?
RETURN
TO ECG
CAPTURE?
POWER-DOWN?
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
ISS UE RE AD FRAME
COM M AND ( WRITE TO 0x40)
ECG CAP TURE COMP LET E
POWER- DOW N ADAS 1000
ECGCTL = 0x0
ADAS1000 ST OPS CONVE RTING,
SDI WO RD US E D TO
RECONFI GURE DE V ICE
10997-038
Rev. B | Page 77 of 80
ADAS1000-3/ADAS1000-4 Data Sheet
POWER SUPPLY, GROUNDING, AND DECOUPLING
STRATEGY
The ADAS1000-3/ADAS1000-4 should have ample supply
decoupling of 0.01 μF on each supply pin located as close to the
device pin as possible, ideally right up against the device. In
addition, there should be one 4.7 μF capacitor for each of the
power domains, AVDD and IOVDD, again located as close to
the device as possible. IOVDD is best split from AVDD due to
its noisy nature.
Similarly, the ADCVDD and DVDD power domains each
require one 2.2 μF capacitor with ESR in the range of 0.5 Ω to
2 Ω. The ideal location for each 2.2 μF capacitor is dependent
on package type. For the LQFP package and DVDD decoupling,
the 2.2 μF capacitor is best placed between Pin 30 and Pin 31,
while for ADCVDD, the 2.2 μF capacitor should be placed
between Pin 55 and Pin 56. Similarly for the LFCSP package,
the DVDD 2.2 μF capacitor is ideal between Pin 43 and Pin 44,
and between Pin 22 and Pin 23 for ADCVDD. A 0.01 μF
capacitor is recommended for high frequency decoupling at
each pin. The 0.01 μF capacitors should have low effective series
resistance (ESR) and effective series inductance (ESL), such as
the common ceramic capacitors that provide a low impedance
path to ground at high frequencies to handle transient currents
due to internal logic switching.
Digital lines running under the device should be avoided
because these couple noise onto the device. The analog ground
plane should be allowed to run under the device to avoid noise
coupling. The power supply lines should use as large a trace as
possible to provide low impedance paths and reduce the effects
of glitches on the power supply line. Fast switching digital
signals should be shielded with digital ground to avoid radiating
noise to other parts of the board and should never be run near
the reference inputs. It is essential to minimize noise on VREF
lines. Avoid crossover of digital and analog signals. Traces on
opposite sides of the board should run at right angles to each
other. This reduces the effects of feedthrough throughout the
board. As is the case for all thin packages, take care to avoid
flexing the package and to avoid a point load on the surface of
this package during the assembly process.
During layout of board, ensure that bypass capacitors are placed
as close to the relevant pin as possible, with short, wide traces
ideally on the topside.
AVDD
While the ADAS1000-3/ADAS1000-4 are designed to operate
from a wide supply rail, 3.15 V to 5.5 V, the performance is
similar over the full range, but overall power increases with
increasing voltage.
ADCVDD AND DVDD SUPPLIES
The AVDD supply rail powers the analog blocks in addition to
the internal 1.8 V regulators for the ADC and the digital core.
If using the internal regulators, connect the VREG_EN pin to
AVDD and then use the ADCVDD and DVDD pins for
decoupling purposes.
The DVDD regulator can be used to drive other external digital
circuitry as required; however, the ADCVDD pin is purely
provided for bypassing purposes and does not have available
current for other components.
Where overall power consumption must be minimized, using
external 1.8 V supply rails for both ADCVDD and DVDD
would provide a more efficient solution. The ADCVDD and
DVDD inputs have been designed to be driven externally and
the internal regulators may be disabled by tying VREG_EN pin
directly to ground.
UNUSED PINS/PATHS
In applications where not all ECG paths or functions might be
used, the preferred method of biasing the different functions is
as follows:
• Unused ECG paths power up disabled. For low power
operation, they should be kept disabled throughout
operation. Ideally, these pins should be connected to
RLD_OUT if not being used.
• Unused external respiration inputs can be tied to ground if
not in use.
• If unused, the shield driver can be disabled and output left
to float.
• CM_OUT, CAL_DAC_IO, EE
AA, GPIOx, CLK_IO,
SYNC_GANG can be left open.
DRDY
56BLAYOUT RECOMMENDATIONS
To maximize CMRR performance, pay careful attention to
the ECG path layout for each channel. All channels should be
identical to minimize difference in capacitance across the paths.
Place all decoupling as close to the ADAS1000-3/ADAS1000-4
devices as possible, with an emphasis on ensuring that the
VREF decoupling be prioritized, with VREF decoupling on
the same side as the ADAS1000-3/ADAS1000-4devices, where
possible.
Rev. B | Page 78 of 80
Data Sheet ADAS1000-3/ADAS1000-4
Rev. B | Page 79 of 80
OUTLINE DIMENSIONS
Figure 82. 56-Lead, Lead Frame Chip Scale Package [LFCSP_VQ]
9 mm × 9 mm Body, Very Thin Quad
(CP-56-7)
Dimensions shown in millimeters
Figure 83. 64-Lead Low Profile Quad Flat Package [LQFP]
(ST-64-2)
Dimensions shown in millimeters
06-20-2012-A
8.75
BSC SQ
1
14
42
29 15
28
56
43
0.75
0.65
0.55
0.60
0.42
0.24
0.60
0.42
0.24
0.30
0.23
0.18
6.50 REF
6.05
5.95 SQ
5.85
9.10
9.00 SQ
8.90
0.50
BSC
0.20 REF
12° MAX
0.05 MAX
0.01 NOM
0.70 M A X
0.65 NO M
SEATING
PLANE
TOP VIEW
PIN 1
INDICATOR
0.90
0.85
0.80
BOT TOM V IEW
0.275
0.150
*EXPOSED PAD
*FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO
THE PIN CONF IGURATION AND FUNCT IO N DE SCRI P TI ONS
SECTION OF THIS DATA SHEET.
COM P L IANT TO JEDE C STANDARDS MS-026- BCD
051706-A
TOP VIEW
(PINS DOWN)
1
16
17 33
32
48
4964
0.27
0.22
0.17
0.50
BSC
LE AD PI TCH
12.20
12.0 0 S Q
11.80
PIN 1
1.60
MAX
0.75
0.60
0.45
10.20
10.0 0 SQ
9.80
VIEW A
0.20
0.09
1.45
1.40
1.35
0.08
COPLANARITY
VIEW A
ROTAT E D 9 0° CCW
SEATING
PLANE
0.15
0.05
7°
3.5°
0°
ADAS1000-3/ADAS1000-4 Data Sheet
Rev. B | Page 80 of 80
ORDERING GUIDE
Model1 Option Description
Temperature
Range
Package
Description
Package
Option
ADAS1000-3BSTZ Tray 3 ECG Channels −40°C to +85°C 64-Lead LQFP ST-64-2
ADAS1000-3BSTZ-RL Reel, 1000 −40°C to +85°C 64-Lead LQFP ST-64-2
ADAS1000-3BCPZ Tray −40°C to +85°C 56-Lead LFCSP_VQ CP-56-7
ADAS1000-3BCPZ-RL Reel, 2500 −40°C to +85°C 56-Lead LFCSP_VQ CP-56-7
ADAS1000-4BSTZ Tray 3 ECG Channels, Pace Algorithm, Respiration Circuit −40°C to +85°C 64-Lead LQFP ST-64-2
ADAS1000-4BSTZ-RL Reel, 1000 −40°C to +85°C 64-Lead LQFP ST-64-2
ADAS1000-4BCPZ Tray −40°C to +85°C 56-Lead LFCSP_VQ CP-56-7
ADAS1000-4BCPZ-RL Reel, 2500 −40°C to +85°C 56-Lead LFCSP_VQ CP-56-7
EVAL-ADAS1000SDZ ADAS1000 Evaluation Board Evaluation Kit2
EVAL-SDP-CB1Z System Demonstration Board (SDP), used as a controller
board for data transfer via USB interface to PC
Controller Board3
1 Z = RoHS Compliant Part.
2 This evaluation kit consists of ADAS1000BSTZ × 2 for up to 12-lead configuration. Because the ADAS1000 contains all features, it is the evaluation vehicle for
all ADAS1000 variants.
3 This board allows a PC to control and communicate with all Analog Devices evaluation boards ending in the SD designator.
©2012–2015 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D10997-0-1/15(B)