10-Bit Monitor and Control System with ADC,
DACs, Temperature Sensor, and GPIOs
Data Sheet
AD7292
FEATURES
10-bit SAR ADC
8 multiplexed analog input channels
Single-ended mode of operation
Differential mode of operation
5 V analog input range
VREF, 2 × VREF, or 4 × VREF input ranges
Input measured with respect to AGND or VDD
4 monotonic, 10-bit, 5 V DACs
2 µs settling time
Power-on reset to 0 V
10 mA sink and source capability
Internal temperature sensor
±1°C accuracy
12 general-purpose digital I/O pins
Internal 1.25 V reference
Built-in monitoring features
Minimum and maximum value register for each channel
Programmable alert thresholds
Programmable hysteresis
SPI interface
Temperature range: −40°C to +125°C
Package type: 36-lead LFCSP
APPLICATIONS
Base station power amplifier (PA) monitoring and control
RF control loops
Optical communication system control
General-purpose system monitoring and control
FUNCTIONAL BLOCK DIAGRAM
CONTROL
LOGIC
BUF
AD7292
T/H
VIN1
VIN6
MUX
VIN7
VIN0
VOUT1
REF
OUT
BUF
TEMPERATURE
SENSOR
10-BIT
SAR ADC
10-BIT
DAC
10-BIT
DAC
10-BIT
DAC
10-BIT
DAC
VOUT2
VOUT3
VOUT0
SPI
INTERFACE
GPIO0/ALERT0
GPIO1/ALERT1
GPIO2/DAC DIS ABLE0
GPIO5
GPIO4/DAC DIS ABLE1
GPIO3/LDAC
VIN2
VIN5
GPIO6/BUSY
A
GND
GPIO7
GPIO8
GPIO9
GPIO10
GPIO11
DV
DD
AV
DD
D
GND
DIN
SCLK
DOUT
CS
VIN4
VIN3
V
DRIVE
DIGITAL I/Os
ALERT AND LIMI T
REGISTERS
1.25V
REF
REF
IN
÷4
10660-001
Figure 1.
GENERAL DESCRIPTION
The AD7292 contains all the functionality required for general-
purpose monitoring of analog signals and control of external
devices, integrated into a single-chip solution. The AD7292
features an 8-channel, 10-bit SAR ADC, four 10-bit DACs, a
±1°C accurate internal temperature sensor, and 12 GPIOs to
aid system monitoring and control.
The 10-bit, high speed, low power successive approximation
register (SAR) ADC is designed to monitor a variety of single-
ended input signals. Differential operation is also available by
configuring VIN0 and VIN1 to operate as a differential pair.
The AD7292 offers a register programmable ADC sequencer,
which enables the selection of a programmable sequence of
channels for conversion.
Four 10-bit digital-to-analog converters (DACs) provide outputs
from 0 V to 5 V. A n internal, high accuracy, 1.25 V reference
provides a separately buffered reference source for both the ADC
and the DACs.
A high accuracy band gap temperature sensor is monitored and
digitized by the 10-bit ADC to give a resolution of 0.03125°C.
The AD7292 also features built-in limit and alarm functions.
The AD7292 is a highly integrated solution offered in a 36-lead
LFCSP package with an operating temperature range of −40°C
to +125°C.
Rev. A Document Feedback
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AD7292 Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
ADC Specifications ...................................................................... 3
DAC Specifications....................................................................... 4
General Specifications ................................................................. 5
Temperature Sensor Specifications ............................................ 5
Timing Specifications .................................................................. 6
Absolute Maximum Ratings ............................................................ 7
Thermal Resistance ...................................................................... 7
ESD Caution .................................................................................. 7
Pin Configuration and Function Descriptions ............................. 8
Typical Performance Characteristics ........................................... 10
Theory of Operation ...................................................................... 15
Analog Inputs .............................................................................. 15
ADC Transfer Functions ........................................................... 16
Temperature Sensor ................................................................... 17
DAC Operation ........................................................................... 17
Digital I/O Pins ........................................................................... 17
Serial Port Interface (SPI) .............................................................. 18
Interface Protocol ....................................................................... 18
Register Structure ........................................................................... 20
Register Descriptions ..................................................................... 21
Vendor ID Register (Address 0x00) ......................................... 21
ADC Data Register (Address 0x01) ......................................... 21
ADC Sequence Register (Address 0x03) ................................. 21
Configuration Register Bank (Address 0x05) .......................... 21
Alert Limits Register Bank (Address 0x06) ............................ 30
Alert Flags Register Bank (Address 0x07) .............................. 31
Minimum and Maximum Register Bank (Address 0x08) .... 32
Offset Register Bank (Address 0x09) ....................................... 32
DAC Buffer Enable Register (Address 0x0A) ......................... 33
GPIO Register (Address 0x0B) ................................................. 33
Conversion Command Register (Address 0x0E) ................... 34
ADC Conversion Result Registers, VIN0 to VIN7
(Address 0x10 to Address 0x17) ............................................... 34
TSENSE Conversion Result Register (Address 0x20) ................ 34
DAC Channel Registers (Address 0x30 to Address 0x33) .... 34
ADC Conversion Control ............................................................. 35
ADC Conversion Command .................................................... 35
ADC Sequencer .......................................................................... 36
DAC Output Control ..................................................................... 37
LDAC Operation ........................................................................ 37
Simultaneous Update of All DAC Outputs ............................. 37
Alerts and Limits ............................................................................ 38
Alert Limit Monitoring Features .............................................. 38
Hardware Alert Pins................................................................... 38
Alert Flag Bits in the Conversion Result Registers ................ 38
Alert Flags Register Bank .......................................................... 39
Minimum and Maximum Conversion Results ...................... 39
Outline Dimensions ....................................................................... 40
Ordering Guide .......................................................................... 40
REVISION HISTORY
9/14—Rev. 0 to Rev. A
Changes to Figure 2 .......................................................................... 6
Changed t11 from 4 ns max to 4 ns min and Removed
Endnote 4; Table 5 .......................................................................... 21
Changes to Figure 35 ...................................................................... 18
Changes to Table 15 ........................................................................ 21
Changes to VIN Filter Subregister (Address 0x13) Section,
Conversion Delay Control Subregister (Address 0x14) Section,
Table 23, and Table 24 .................................................................... 26
Changes to VIN ALERT0 Routing and VIN ALERT1 Routing
Subregisters (Address 0x15 and Address 0x16) Section,
Table 25, and Table 26 .................................................................... 27
Changes to Figure 40 and Figure 41 ............................................ 35
Changes to Figure 42 ...................................................................... 36
10/12—Revision 0: Initial Version
Rev. A | Page 2 of 40
Data Sheet AD7292
SPECIFICATIONS
ADC SPECIFICATIONS
AVDD = 4.75 V to 5.25 V, DVDD = 1.8 V to 5.25 V, VREF = 1.25 V internal, VDRIVE = 1.8 V to 5.25 V, AGND = 0 V, TA = −40°C to +125°C,
unless otherwise noted. Specifications apply to single-ended mode only, unless otherwise noted.
Table 1.
Parameter Min Typ Max Unit Test Conditions/Comments
DC ACCURACY
Resolution 10 Bits
Integral Nonlinearity (INL)
1
±0.11
±0.5
LSB
±0.6 LSB (AVDD − 4 × VREF) to AVDD input range
Differential Nonlinearity (DNL)1 ±0.1 ±0.99 LSB
Offset Error ±3 ±8 mV
±12 mV (AVDD − 4 × VREF) to AVDD input range
Offset Error Matching 0.5 ±1 mV
Offset Error Drift ±0.22 ppm/°C
Gain Error ±0.09 ±0.25 % FS
±0.36 % FS (AVDD − 4 × VREF) to AVDD input range
Gain Error Matching ±0.5 % FS
Gain Error Drift ±4.17 ppm/°C
DYNAMIC PERFORMANCE1 fIN = 10 kHz sine wave
Signal-to-Noise Ratio (SNR) 61.5 dB
Signal-to-Noise-and-Distortion (SINAD)
Ratio
61.5 dB
Total Harmonic Distortion (THD) −84 dB
Spurious-Free Dynamic Range (SFDR) 84.5 dB
Channel-to-Channel Isolation −80 dB fIN = 3 kHz to 1000 kHz
Full Power Bandwidth 60 MHz At −3 dB (0 V to VREF input range)
3 MHz At −0.1 dB (0 V to VREF input range)
CONVERSION RATE
Conversion Time 900 ns See Table 5
Track-and-Hold Acquisition Time 45 ns
Throughput Rate 625 kSPS ADC only; temperature sensor
disabled
150 kSPS ADC and temperature sensor
ANALOG INPUT
Single-Ended Input Range
With Respect to AGND 0 4 × VREF V
0 2 × VREF V
0 VREF V
With Respect to AV
DD
AV
DD
− 4 × V
REF
AV
DD
V
Fully Differential Input Range −4 × VREF +4 × VREF V VIN0 and VIN1 inputs only
−2 × VREF +2 × VREF V
−VREF +VREF V
Input Capacitance 23 pF 0 V to VREF input range
18
pF
0 V to 2 × V
REF
input range
15 pF 0 V to 4 × VREF input range
DC Input Leakage Current ±1 µA
INTERNAL REFERENCE
Reference Output Voltage 1.245 1.25 1.255 V At 25°C
Reference Temperature Coefficient ±13 ppm/°C
Rev. A | Page 3 of 40
AD7292 Data Sheet
Parameter Min Typ Max Unit Test Conditions/Comments
EXTERNAL REFERENCE
Reference Input Voltage 4.75 AVDD V Internal reference used to calibrate
temperature sensor
Input Resistance 100 kΩ
1 Specifications also apply to differential mode.
DAC SPECIFICATIONS
AVDD = 4.75 V to 5.25 V, DVDD = 1.8 V to 5.25 V, VREF = 1.25 V internal, VDRIVE = 1.8 V to 5.25 V, AGND = 0 V, TA = −40°C to +125°C,
unless otherwise noted.
Table 2.
Parameter Min Typ Max Unit Test Conditions/Comments
DC ACCURACY
Resolution 10 Bits
Integral Nonlinearity (INL) ±0.2 ±1 LSB
Differential Nonlinearity (DNL) ±0.1 ±0.3 LSB Guaranteed monotonic
Zero-Scale Error 4.8 ±10 mV All 0s loaded to DAC register
Full-Scale Error ±0.1 ±0.5 % FS All 1s loaded to DAC register
Offset Error ±1.62 ±10 mV Measured in the linear region,
TA = −40°C to +125°C
Offset Error Drift ±4.4 ppm/°C Measured in the linear region, TA = 25°C
Gain Error ±0.35 ±0.5 % FS
Gain Error Drift ±2.6 ppm/°C
DC Power Supply Rejection Ratio (PSRR) −50 dB fRIPPLE up to 100 kHz
DC Crosstalk 5 μV
DAC OUTPUT CHARACTERISTICS
Output Voltage Range 0 4 × VREF V
Short-Circuit Current ±30 mA
Load Current ±10 mA Sink/source current; within ±200 mV
of supply
Resistive Load to AGND 500 Ω
Capacitive Load Stability 1 nF
DC Output Impedance 1 Ω
AC CHARACTERISTICS1
Output Voltage Settling Time 1 2 µs ¼ to ¾ scale step change within 1 LSB,
measured from last SCLK edge
Overshoot 200 mV ¼ to ¾ scale step change within 1 LSB,
measured from last SCLK edge;
CL = 200 pF, RL = 25 kΩ
Slew Rate 9 12 V/µs
Digital-to-Analog Glitch Impulse 4 nV-sec
Digital Feedthrough 0.4 nV-sec
DAC-to-DAC Crosstalk 2 nV-sec
Output Noise Spectral Density 730 nV/√Hz DAC code = midscale, 1 kHz
Output Noise 28 μV rms 0.1 Hz to 10 Hz
Output Transient Response During
Power-Up
5 mV AVDD ramp of 1 ms with 100 kΩ load
1 The DAC buffer output level is undefined until 30 µs after all supplies reach their minimum specified operating voltages.
Rev. A | Page 4 of 40
Data Sheet AD7292
GENERAL SPECIFICATIONS
AVDD = 4.75 V to 5.25 V, DVDD = 1.8 V to 5.25 V, VREF = 1.25 V internal, VDRIVE = 1.8 V to 5.25 V, AGND = 0 V, TA = −40°C to +125°C,
unless otherwise noted.
Table 3.
Parameter Min Typ Max Unit Test Conditions/Comments
LOGIC INPUTS
Input High Voltage, VIH 0.7 × VDRIVE V VDRIVE = 2.3 V to 5.25 V
0.8 × VDRIVE V VDRIVE = 1.8 V to 1.95 V
Input Low Voltage, VIL 0.3 × VDRIVE V VDRIVE = 2.3 V to 5.25 V
0.2 × VDRIVE V VDRIVE = 1.8 V to 1.95 V
Input Leakage Current, IIN ±1 µA
Input Capacitance, CIN 3 pF
Input Hysteresis, VHYST 0.05 × VDRIVE V
GPIO OUTPUTS
ISINK/ISOURCE 1.6 mA
Output High Voltage, VOH DVDD − 0.2 V ISINK/ISOURCE = 1.6 mA
Output Low Voltage, VOL 0.4 V ISINK/ISOURCE = 1.6 mA
POWER REQUIREMENTS
AVDD 4.75 5.25 V
DVDD 1.8 5.25 V
VDRIVE 1.8 5.25 V
Static Current
IAVDD 4.2 5.4 mA
IDVDD 0.65 1.3 mA
IDRIVE 0.12 0.35 mA
Total Static Current 4.97 mA AVDD + DVDD + VDRIVE
Dynamic Current
IAVDD 6.45 8.5 mA
IDVDD 0.65 1.3 mA
IDRIVE 0.12 0.35 mA
Total Dynamic Current 7.22 mA AVDD + DVDD + VDRIVE, DAC outputs loaded
and converting at full scale, continuous
conversion on ADC inputs
Power Dissipation
Static 26 34.125 mW
Dynamic 37.9 50.925 mW
TEMPERATURE SENSOR SPECIFICATIONS
AVDD = 4.75 V to 5.25 V, DVDD = 1.8 V to 5.25 V, VREF = 1.25 V internal, VDRIVE = 1.8 V to 5.25 V, AGND = 0 V, TA = −40°C to +125°C,
unless otherwise noted.
Table 4.
Parameter Min Typ Max Unit Test Conditions/Comments
INTERNAL TEMPERATURE SENSOR
Operating Range
−40
+125
°C
Accuracy ±1 ±3 °C TA = −40°C to +125°C
±1 ±2 °C TA = 0°C to +125°C
0.5 ±1.5 °C TA = 25°C
Resolution 0.03125 °C Digital filter enabled
Update Rate 1.25 ms
Rev. A | Page 5 of 40
AD7292 Data Sheet
Rev. A | Page 6 of 40
TIMING SPECIFICATIONS
AVDD = 4.75 V to 5.25 V, DVDD = 1.8 V to 5.25 V, VREF = 1.25 V internal, VDRIVE = 1.8 V to 5.25 V, AGND = 0 V, CL = 27 pF, TA = −40°C
to +125°C, unless otherwise noted.1
Table 5.
Limit at TMIN/TMAX
Parameter Description VDRIVE = 1.8 V VDRIVE = 2.7 V to 5.25 V Unit
tCONVERT ADC conversion time/BUSY high time
Temperature sensor disabled 950 950 ns max
Temperature sensor enabled 5.85 5.85 μs max
tACQ ADC acquisition time 50 50 ns max
fSCLK Frequency of serial read clock2 15 25 MHz max
t1 SCLK period 66 40 ns min
t2 SCLK low 33 20 ns min
t3 SCLK high 33 20 ns min
t4 CS falling edge to SCLK rising edge 4 4 ns min
t5 DIN setup time to SCLK falling edge 4 4 ns min
t63 DIN hold time after SCLK falling edge 2 2 ns max
t7 SCLK falling edge to CS rising edge 5 5 ns min
t8 CS high 5 5 ns min
t9 SCLK to output data valid delay time 30 19 ns max
t10 SCLK to output data valid hold time 7 5 ns min
t114 CS rising edge to SCLK rising edge 4 4 ns min
t12 CS rising edge to DOUT high impedance 15 15 ns max
1 Sample tested during initial release to ensure compliance. All input signals are specified with tR = tF = 5 ns (10% to 90% of VDRIVE).
2 For VDRIVE = 2.5 V, fSCLK = 22 MHz maximum.
3 Time required for the output to cross 0.2 × VDRIVE and 0.8 × VDRIVE when VDRIVE = 1.8 V; time required for the output to cross 0.3 × VDRIVE and 0.7 × VDRIVE when VDRIVE = 2.7 V to 5.25 V.
4 Guaranteed by design.
Timing Diagram
10660-002
RX W D5 D4 D3 D2 D1 D0 LSB X
LSB
t
4
t
5
t
6
t
3
t
2
t
1
t
7
t
8
t
11
t
12
t
10
t
9
HIGH-Z HIGH-Z
BUSY
2
CS
SCLK
DIN
DOUT
1
1
PROV I D ED T HE READ BI T I S SE T .
2
IF AN ADC CONVERSION IS REQUES TED.
t
7
= 5ns I F NO ADC CONVERS ION
955ns WITH ADC CONVE RS IO N
Figure 2. Serial Interface Timing Diagram
Data Sheet AD7292
ABSOLUTE MAXIMUM RATINGS
TA = 25°C, unless otherwise noted.
Table 6.
Parameter Rating
AVDD to AGND −0.3 V to +6 V
DVDD to DGND −0.3 V to +6 V
VDRIVE to DGND −0.3 V to +6 V
VINx to AGND −0.3 V to AVDD + 0.3 V
VOUTx to AGND −0.3 V to AVDD + 0.3 V
Digital Inputs/Outputs to DGND −0.3 V to DVDD + 0.3 V
CS
, SCLK, DIN, DOUT to D
GND
−0.3 V to V
DRIVE
+ 0.3 V
REFOUT to AGND −0.3 V to +2.2 V
REFIN to AGND −0.3 V to AVDD + 0.3 V
DGND to AGND 0.3 V
Operating Temperature Range −40°C to +125°C
Storage Temperature Range −65°C to +150°C
Junction Temperature (TJ max) 150°C
ESD, Human Body Model 2.5 kV
Reflow Soldering Peak Temperature 260°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
THERMAL RESISTANCE
Table 7. Thermal Resistance
Package Type θJA Unit
36-Lead LFCSP 54.1 °C/W
ESD CAUTION
Rev. A | Page 7 of 40
AD7292 Data Sheet
Rev. A | Page 8 of 40
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
NOTES
1. THE EXPOSED PAD IS INTERNALLY CONNECTED TO A
GND
AND
CAN BE S OLDERED TO T HE GROUND PL A NE OF T HE SYSTEM.
1AV
DD
2
A
GND
3
D
GND
4
DV
DD
5V
DRIVE
6
CS 7SCLK 8DIN 9DOUT
27 GPIO0/ALERT0
26 GPIO1/ALERT1
25 GP IO 2/DAC DISABLE0
24 GPIO3/LDAC
23 GP IO 4/DAC DISABLE1
22 GPIO5
21 GPIO6/BUSY
20 GPIO7
19 REF
OUT
10VOUT3 11VOUT2 12VOUT1 13VOUT0 14A
GND
15GPIO11 16GPIO10 17GPIO9 18GPIO8
36 REF
IN
35 VIN7
34 VIN6
33 VIN5
32 VIN4
31 VIN3
30 VIN2
29 VIN1
28 VIN0
10660-003
AD7292
TOP VIEW
(Not to Scale)
Figure 3. Pin Configuration
Table 8. Pin Function Descriptions
Pin No. Mnemonic Description
1 AVDD Supply Pin. This pin should be decoupled to AGND with a 0.1 μF decoupling capacitor.
2, 14 AGND Analog Ground. Ground reference point for all analog circuitry on the AD7292. All analog signals should
be referred to AGND. Both the AGND and DGND pins should be connected to the ground plane of the system.
3 DGND Digital Ground. Ground reference point for all digital circuitry on the AD7292. All digital signals should be
referred to DGND. Both the DGND and AGND pins should be connected to the ground plane of the system.
4 DVDD Sets the GPIO voltage level. This pin should be decoupled to DGND with a 0.1 μF decoupling capacitor.
5 VDRIVE This pin sets the reference level of the SPI bus from 1.8 V to 5.25 V. This pin should be decoupled to DGND
with a 0.1 μF decoupling capacitor.
6 CS Chip Select Signal. This active low logic input signal is used to frame the serial data input.
7 SCLK SPI Clock Input.
8 DIN SPI Serial Data Input. Serial data to be loaded into the registers of the AD7292 is provided on this pin.
Data is clocked into the serial interface on the falling edge of SCLK.
9 DOUT SPI Serial Data Output. Serial data to be read from the registers of the AD7292 is provided on this pin.
Data is clocked out on the rising edge of SCLK. DOUT is high impedance when it is not outputting data.
10 to 13 VOUT3 to VOUT0 Buffered DAC Analog Outputs. Each DAC analog output is driven from an output amplifier and has a
maximum output voltage span of 5 V. Each DAC is capable of sourcing and sinking 10 mA and driving a
1 nF load.
15 to 18 GPIO11 to GPIO8 General-Purpose Input/Output Pins.
19 REFOUT ADC Internal Reference Output. Decouple the internal ADC reference buffer to AGND with a 0.1 μF
decoupling capacitor.
20 GPIO7 General-Purpose Input/Output Pin.
21 GPIO6/BUSY General-Purpose Input/Output Pin (GPIO6).
Busy Output Pin (BUSY). When a conversion starts, this output pin transitions high and remains high until
the conversion is completed.
22 GPIO5 General-Purpose Input/Output Pin.
23 GPIO4/
DAC DISABLE1
General-Purpose Input/Output Pin (GPIO4).
DAC Disable Pin 1 (DAC DISABLE1). When this pin is activated, the selected DAC outputs are disabled.
Select the DAC channels to be disabled by this pin using the GPIO4/DAC DISABLE1 subregister within the
configuration register bank (see Table 30).
24 GPIO3/LDAC General-Purpose Input/Output Pin (GPIO3).
LDAC Input Pin (LDAC). When this input is taken high, the DAC registers are updated.
25 GPIO2/
DAC DISABLE0
General-Purpose Input/Output Pin (GPIO2).
DAC Disable Pin 0 (DAC DISABLE0). When this pin is activated, the selected DAC outputs are disabled.
Select the DAC channels to be disabled by this pin using the GPIO2/DAC DISABLE0 subregister within the
configuration register bank (see Table 29).
Data Sheet AD7292
Pin No. Mnemonic Description
26 GPIO1/ALERT1 General-Purpose Input/Output Pin (GPIO1).
Alert Pin 1 (ALERT1). When configured as an alert, this pin acts as an out-of-range indicator and becomes
active when the conversion result violates the high or low limit stored in the alert limits register bank. The
polarity of the alert signal is controlled using the general subregister within the configuration register bank.
27 GPIO0/ALERT0 General-Purpose Input/Output Pin (GPIO0).
Alert Pin 0 (ALERT0). When configured as an alert, this pin acts as an out-of-range indicator and becomes
active when the conversion result violates the high or low limit stored in the alert limits register bank. The
polarity of the alert signal is controlled using the general subregister within the configuration register bank.
28 to 35 VIN0 to VIN7 Analog Inputs. The eight single-ended analog inputs of the AD7292 are multiplexed into the on-chip
track-and-hold amplifier. Each input channel can accept analog inputs from 0 V to 5 V. Any unused input
channels should be connected to AGND to avoid noise pickup.
36 REFIN Voltage Reference Input. An external reference for the AD7292 can be applied to this pin. If this pin is
unused, connect it to AGND.
EPAD EPAD The exposed pad is internally connected to AGND and can be soldered to the ground plane of the system.
Rev. A | Page 9 of 40
AD7292 Data Sheet
TYPICAL PERFORMANCE CHARACTERISTICS
–120
–100
–80
–60
–40
–20
0
010 20 30 40 50 60 70 80 90 100
AMPLITUDE (dB)
INPUT F RE QUENCY (kHz )
AVDD = 5V
DVDD = 5V
VDRIVE = 3V
TA = 25° C
f
SAMPLE = 200kS P S
RANGE = 0V TO VREF
SINGLE-ENDED MODE
SNR = 61. 6dB
THD = –84.0d B
SINAD = 61.49d B
SFDR = 79.05d B
10660-004
Figure 4. ADC FFT, 200 kSPS, fIN = 10 kHz, Single-Ended Mode
–0.3
–0.2
–0.1
0
0.1
0.2
0.3
0128 256 384 512 640 768 896 1024
INL ERROR ( LSB)
ADC CODE
AV
DD
= DV
DD
= 5.25V
V
DRIVE
=1.8V
CHANNEL 3
INTERNAL REFERENCE
T
A
=25°C
WCP INL = 0.068LSB
WCN INL = –0.255LSB
10660-006
SINGLE-ENDED MODE, 0V TO 4 × V
REF
RANGE
Figure 5. Typical ADC INL, Single-Ended Mode
–0.3
–0.2
–0.1
0
0.1
0.2
0.3
0128 256 384 512 640 768 896 1024
DNL ERRO R ( LSB)
ADC CODE
AVDD = DVDD = 5.25V
VDRIVE = 1.8V
CHANNEL 3
INTERNAL REFERENCE
TA=25°C
WCP DNL = 0.11LSB
WCN DNL = –0.119LSB
SINGLE-ENDED MODE, 0V TO 4 × VREF RANGE
10660-007
Figure 6. Typical ADC DNL, Single-Ended Mode
–120
–100
–80
–60
–40
–20
0
010 20 30 40 50 60 70 80 90 100
AMPLITUDE (dB)
INPUT F RE QUENCY (kHz )
10660-005
AVDD = 5V
DVDD = 5. 25V
VDRIVE = 1.8V
TA = 25° C
f
SAMPLE = 200kS P S
RANGE = 0V TO 2 × VREF
DIFFERENTIAL MODE
SNR = 61. 798dB
THD = –86.602d B
SINAD = 61.784d B
SFDR = 86.142d B
Figure 7. ADC FFT, 200 kSPS, fIN = 10 kHz, Differential Mode
–0.3
–0.2
–0.1
0
0.1
0.2
0.3
0128 256 384 512 640 768 896 1024
INL ERROR ( LSB)
ADC CODE
DVDD = 5.25V
AVDD =4.75V
VDRIVE =3.3V
CHANNEL0AND CHANNEL 1
INTERNAL REFERENCE
TA=25°C
WCP INL = 0.091LSB
WCN INL = –0.093LSB
DIFFERENTIALMODE, 0V TO VREF RANGE
10660-008
Figure 8. Typical ADC INL, Differential Mode
0128 256 384 512 640 768 896 1024
DNL ERRO R ( LSB)
ADC CODE
10660–009
–0.25
–0.20
–0.15
–0.10
–0.05
0
0.05
0.10
0.15
0.20
0.25
DVDD = 5.25V
AVDD =4.75V
VDRIVE =3.3V
CHANNEL 0AND CHANNEL 1
INTERNAL REFERENCE
TA=25°C
WCP INL = 0.067LSB
WCN INL = –0.08LSB
DIFFERENTIAL MODE, 0V TO VREF RANGE
Figure 9. Typical ADC DNL, Differential Mode
Rev. A | Page 10 of 40
Data Sheet AD7292
–1.0
–0.8
–0.6
–0.4
–0.2
0
0.2
0.4
0.6
0.8
1.0
–40 –20 020 40 60 80 100 120
INL ERRO R ( LSB)
TEMPERATURE (°C)
AV
DD
= 5V
DV
DD
= 3V
V
DRIVE
= 3V
f
SAMPLE
= 225kSPS
INTERNAL RE FERENCE
SINGLE-ENDED MODE
0V TO V
REF
, –I NL
0V TO V
REF
, +INL
0V TO 2 × V
REF
, –I NL
0V TO 2 × V
REF
, +INL
0V TO 4 × V
REF
, –I NL
0V TO 4 × V
REF
, +INL
(AV
DD
– 4 × V
REF
) TO AV
DD
, –I NL
(AV
DD
– 4 × V
REF
) TO AV
DD
, +INL
10660-010
Figure 10. ADC INL vs. Temperature
–3
–2
–1
0
1
2
3
–40 –20 020 40 60 80 100 120
OFFSET ERROR (LSB)
TEMPERATURE (°C)
0V TO 4 × V
REF
0V TO V
REF
0V TO 2 × V
REF
(AV
DD
– 4 × V
REF
) TO AV
DD
AV
DD
= 5.25V
DV
DD
= 5V
V
DRIVE
= 3.3V
f
SAMPLE
= 200kSPS
INTERNAL RE FERENCE
10660-012
Figure 11. Offset Error vs. Temperature, Single-Ended
and Differential Modes
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
–20
10
100
90
80
70
60
50
40
30
20
THD ( dB)
INPUT F RE QUENCY (kHz )
AV
DD
= 5V
DV
DD
= 3V
V
DRIVE
= 3V
fSAMPLE
= 225kSPS
T
A
= 25° C
INTERNAL RE FERENCE
AV
DD
– 4 × V
REF,
0Ω
AV
DD
– 4 × V
REF,
220Ω
AV
DD
– 4 × V
REF,
510Ω
0V TO 4 × V
REF,
0Ω
0V TO 4 × V
REF,
220Ω
0V TO 4 × V
REF,
430Ω
0V TO 4 × V
REF,
510Ω
0V TO V
REF,
0Ω
0V TO V
REF,
220Ω
0V TO V
REF,
510Ω
0V TO 2 × V
REF,
0Ω
0V TO 2 × V
REF,
220Ω
0V TO 2 × V
REF,
510Ω
10660-014
Figure 12. THD vs. Input Frequency for Various Source Impedances,
Single-Ended Mode
–0.4
–0.3
–0.2
–0.1
0
0.1
0.2
0.3
0.4
–40 –20 020 40 60 80 100 120
DNL ERROR (LSB)
TEMPERATURE (°C)
AV
DD
= 5V
DV
DD
= 3V
V
DRIVE
= 3V
fSAMPLE
= 225kSPS
INTERNAL RE FERENCE
SINGLE-ENDED MODE
0V TO V
REF
, –DNL
0V TO V
REF
, +DNL
0V T O 2 × V
REF
, –DNL
0V T O 2 × V
REF
, +DNL
0V T O 4 × V
REF
, –DNL
0V T O 4 × V
REF
, +DNL
(AV
DD
– 4 × V
REF
) TO AV
DD
, –DNL
(AV
DD
– 4 × V
REF
) TO AV
DD
, +DNL
10660-011
Figure 13. ADC DNL vs. Temperature
–5
–4
–3
–2
–1
0
1
2
3
4
5
–40 –20 020 40 60 80 100 120
GAI N E RROR (LSB)
TEMPERAT URE ( °C)
0V TO 4 × V
REF
0V TO 2 × V
REF
(AV
DD
– 4 × V
REF
) TO AV
DD
0V TO V
REF
AV
DD
= 5.25V
DV
DD
= 5V
V
DRIVE
= 3.3V
fSAMPLE
= 200kSPS
INT E RNAL REFERENCE
10660-013
Figure 14. ADC Gain Error vs. Temperature, Single-Ended
and Differential Modes
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
100 1k 10k 100k 1M 10M 100M
CHANNEL-TO-CHANNEL ISOLATION (dB)
INPUT F RE QUENCY (Hz)
AV
DD
= 5V
DV
DD
= 3V
V
DRIVE
= 3V
f
SAMPLE
= 250kSPS
f
IN
= 10kHz
INTERNAL RE FERENCE
FULL- S CALE SIGNAL ON CHANNE L,
VIN0 TO V IN3 AND VI N5 TO V IN7
INPUT F RE QUENCY RAM P E D M E AS URE M E NTS O N V IN4
T
A
= 25° C 0V TO V
REF
0V TO 2 × V
REF
0V TO 4 × V
REF
(AV
DD
– 4 × V
REF
) TO AV
DD
10660-016
Figure 15. ADC Channel-to-Channel Isolation
Rev. A | Page 11 of 40
AD7292 Data Sheet
0
100
200
300
400
500
600
700
800
900
511 512
OCCURRENCES
OUTPUT CODE
510
10660-017
AV
DD
= 5V
DV
DD
= 5V
V
DRIVE
= 2.5V
T
A
= 25° C
Figure 16. Histogram of Codes
–0.5
–0.3
–0.1
0.1
0.3
0.5
0128 256 384 512 640 768 896 1024
INL ERROR ( LSB)
DAC CODE
AV
DD
= 5.25V
DV
DD
= 5V
V
DRIVE
= 3.3V
INTERNAL RE FERENCE
T
A
= 25° C
10660-019
Figure 17. Typical DAC INL vs. Output Code
–1.0
–0.9
–0.8
–0.7
–0.6
–0.5
–0.4
–0.3
–0.2
–0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
–40 –20 020 40 60 80 100 120
INL ERRO R ( LSB)
TEMPERATURE (°C)
INL MAX
INL MIN
AV
DD
= 5.25V
DV
DD
= 5V
V
DRIVE
= 3.3V
INT E RNAL REFERENCE
10660-021
Figure 18. DAC INL vs. Temperature
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1k 10k 100k 1M
REFERENCE VOLTAGE (V)
LO AD RE S ISTANCE (Ω)
AVDD = 5V
DVDD = VDRIVE = 3V
fSAMPLE = 225kS P S
TA = 25° C
ANALO G I NP UT RANGE = AV
DD
– 4 × V
REF
10660-018
Figure 19. Reference Voltage vs. Load Resistance
–0.25
–0.15
–0.05
0.05
0.15
0.25
0128 256 384 512 640 768 896 1024
DNL ERRO R ( LSB)
DAC CODE
10660-020
AV
DD
= 5.25V
DV
DD
= 5V
V
DRIVE
= 3.3V
INTERNAL RE FERENCE
T
A
= 25° C
Figure 20. Typical DAC DNL vs. Output Code
–1.0
–0.9
–0.8
–0.7
–0.6
–0.5
–0.4
–0.3
–0.2
–0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
–40 –20 020 40 60 80 100 120
DNL ERRO R ( LSB)
TEMPERAT URE ( °C)
DNL MAX
DNL MIN
10660-022
AV
DD
= 5.25V
DV
DD
= 5V
V
DRIVE
= 3.3V
INT E RNAL REFERENCE
Figure 21. DAC DNL vs. Temperature
Rev. A | Page 12 of 40
Data Sheet AD7292
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
–40 –20 020 40 60 80 100 120
OFF SET ERROR (mV)
TEMPERAT URE ( °C)
AV
DD
=5.25V
AV
DD
=4.75V
DV
DD
= 5V
V
DRIVE
= 3.3V
INTERNAL RE FERENCE
10660-023
Figure 22. DAC Offset Error vs. Temperature
4.988
4.989
4.990
4.991
4.992
4.993
4.994
4.995
4.996
0 1 2 3 4567 8 9 10
OUTPUT VOLTAGE (V)
SOURCE CURRE NT (mA)
AV
DD
= 5.25V
DV
DD
= 5V
V
DRIVE
= 3.3V
INTERNAL RE FERENCE
CODE = 0x3FF
T
A
= 25° C
10660-026
Figure 23. DAC Source Current (Full Scale)
2.494
2.496
2.498
2.500
2.502
2.504
2.506
2.508
2.510
–10 –8 –6 –4 –2 0246810
OUTPUT VOLTAGE (V)
LOAD CURRENT ( mA)
AV
DD
=5.25V
DV
DD
= 5V
V
DRIVE
= 3.3V
INTERNAL REFERENCE
CODE = 0x200
10660-025
Figure 24. DAC Output Voltage vs. Load Current (Midscale)
–0.4
–0.3
–0.2
–0.1
0
0.1
0.2
0.3
0.4
–40 –20 020 40 60 80 100 120
GAI N E RROR (%FSR)
TEMPERATURE (°C)
AVDD = 5. 25V
AVDD = 4. 75V
DVDD = 5V
VDRIVE = 3.3V
INTERNAL RE FERENCE
10660-024
Figure 25. DAC Gain Error vs. Temperature
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
01 2 3 45678910
OUTPUT VOLTAGE (V)
SINK CURRE NT (mA)
AV
DD
= 5.25V
DV
DD
= 5V
V
DRIVE
= 3.3V
INTERNAL RE FERENCE
CODE = 0x000
T
A
= 25° C
10660-027
Figure 26. DAC Sink Current (Zero Scale)
1.245
1.247
1.249
1.251
1.253
1.255
1.246
1.248
1.250
1.252
1.254
–40 –20 0
20
40 60 80 100 120
REFERENCE VOLTAGE (V)
TEMPERAT URE ( °C)
AVDD = DVDD = VDRIVE = 5V
10 DEVICES
10660-028
Figure 27. Reference Voltage vs. Temperature
Rev. A | Page 13 of 40
AD7292 Data Sheet
–40 –20 020 40 60 80 100 120
ERROR (°C)
TEMPERAT URE ( °C)
10660-031
–0.4
–0.2
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
AVDD = DVDD = VDRIVE = 5V
10 DEVICES
Figure 28. Temperature Sensor Error vs. Temperature
0
10
20
30
40
50
60
70
80
1k 10k 100k 1M 10M
PSRR (dB)
POWER SUPPLY RIPPLE FREQUENCY (Hz)
0V TO V
REF
0V TO 2 × V
REF
0V TO 4 × V
REF
AV
DD
= 5V
DV
DD
= 3V
V
DRIVE
= 3V
fSAMPLE
= 225kSPS
INTERNAL RE FERENCE
T
A
= 25° C
10660-032
Figure 29. PSRR vs. Power Supply Ripple Frequency
4.0
4.2
4.4
4.6
4.8
5.0
5.2
5.4
5.6
5.8
6.0
0100 200 300 400 500 600
TOTAL CURRENT ( mA)
SAMP LING FRE QUENCY (kHz)
AV
DD
= 5 V, DV
DD
= 3V, V
DRIVE
= 3 V, SCLK VARIED
AV
DD
= 5. 25V, DV
DD
= 5. 25V, V
DRIVE
= 5. 25V, SCLK FIXED, 25MHz
AV
DD
= 4. 75V, DV
DD
= 1. 8V, V
DRIVE
= 1 .8V, SCLK FIXED, 15 MHz
10660-033
Figure 30. Total Supply Current vs. Throughput Rate
Rev. A | Page 14 of 40
Data Sheet AD7292
THEORY OF OPERATION
ANALOG INPUTS
The AD7292 has eight analog input channels. By default, these
channels are configured as single-ended inputs. Differential
operation is also available by configuring VIN0 and VIN1 to
operate as a differential pair.
Single-Ended Mode
In applications where the signal source has high impedance, it
is recommended that the analog input be buffered before it is
applied to the ADC.
The analog input range is programmed to one of these values:
0 V to VREF, 0 V to 2 × VREF, or 0 V to 4 × VREF. For information
about programming the input range, see the VIN RANGE0 and
VIN RANGE1 Subregisters (Address 0x10 and Address 0x11)
section.
In 0 V to 2 × VREF mode, the input is scaled by a factor of 2 before
the conversion takes place. In 0 V to 4 × VREF mode, the input
is scaled by a factor of 4 before the conversion takes place. Note
that the voltage with respect to AGND on the ADC analog input
pins cannot exceed AVDD.
If the analog input signal to be sampled is bipolar, the internal
reference of the ADC can be used to externally bias this signal
up so that it is correctly formatted for the ADC. Figure 31 shows
a typical connection diagram when operating the ADC in single-
ended mode with a bipolar ±0.625 V input signal.
AD7292
REF
OUT
VIN0
0.47µF
0V
+0.625V
–0.625V
VIN7
V
IN
R
R
R
3R
0V
+1.25V
10660-037
Figure 31. Interfacing to a Bipolar Input Signal
Differential Mode
The AD7292 can be configured to have one differential analog
input pair (VIN0 and VIN1). Differential signals have some
benefits over single-ended signals, including noise immunity
based on the common-mode rejection of the device and improve-
ments in distortion performance. Figure 32 shows the fully
differential analog input of the AD7292.
V
REF
p-p V
IN+
VIN0
AD7292
COMMON-MODE
VOLTAGE VIN1
V
IN–
V
REF
p-p
10660-038
Figure 32. Differential Analog Input
The amplitude of the differential signal is the difference
between the signals applied to the input pins of the differential
pair, VIN0 and VIN1. The resulting converted data is stored in
straight binary format in the ADC data register. VIN0 and VIN1
should be simultaneously driven by two signals that are 180° out
of phase; each signal should be of maximum amplitude VREF,
2 × VREF, or 4 × VREF, depending on the selected range.
Therefore, if the 0 V to VREF range is selected, the amplitude of
the differential signal is −VREF to +VREF peak-to-peak (2 × VREF),
regardless of the common-mode voltage (VCM).
The common-mode voltage is the average of the two signals.
VCM = (VIN+ + VIN−)/2
The common-mode voltage is, therefore, the voltage on which
the two inputs are centered; the resulting span for each input is
VCM ± VREF/2. This voltage must be set up externally. When the
inputs are driven with an amplifier, the actual common-mode
range is determined by the output voltage swing of the amplifier
and the input common-mode range of the AD7292. The common-
mode voltage must be in this range to guarantee the functionality
of the AD7292 (see Figure 33). When a conversion takes place,
the common-mode voltage is rejected, resulting in a virtually
noise-free signal of amplitude −VREF to +VREF.
55
57
59
61
63
65
67
69
00.5 1.0 1.5 2.0 2.5 3.0 3.5
SINAD (dB)
COMMON-MODE VOLTAGE (V)
1 × V
REF
2 × V
REF
4 × V
REF
AV
DD
= 5V
DV
DD
= 3V
V
DRIVE
= 3V
T
A
= 25° C
f
SAMPLE
= 225kSPS
INT E RNAL REFERENCE
DIFFERENTIAL MODE
10660-138
Figure 33. Common-Mode Voltage (Dependent on Input Range)
Rev. A | Page 15 of 40
AD7292 Data Sheet
ADC TRANSFER FUNCTIONS
The output coding of the AD7292 is 10-bit straight binary for the
analog input channels. The designated code transitions occur at
successive LSB values.
To select the input range, set the appropriate bits in the VIN
RANGE1 and VIN RANGE0 subregisters of the configuration
register bank (see Table 10).
The LSB size depends on the input range selected (see Table 9).
Table 9. Input Range and LSB Size
Input Range LSB Size
0 V to VREF VREF/210
0 V to 2 × VREF 2VREF/210
0 V to 4 × VREF 4VREF/210
The ideal transfer function for the AD7292 when operating
with an input range of 0 V to VREF is shown in Figure 34.
Table 10. Analog Input Range Selection
Sample with Respect to AGND Sample with Respect to AVDD2
Subregister Bit Settings1 Single-Ended Input Range Differential Input Range Single-Ended Input Range
VIN RANGE1 VIN RANGE0 (VIN0 to VIN7) (VIN0 and VIN1 Only) (VIN0 to VIN7)
0 0 0 V to 4 × VREF −4 × VREF to +4 × VREF (AVDD − 4 × VREF) to AVDD
0 1 0 V to 2 × VREF −2 × VREF to +2 × VREF Not applicable
1 0 0 V to 2 × VREF −2 × VREF to +2 × VREF Not applicable
1 1 0 V to VREF −VREF to +VREF Not applicable
1 For more information, see the ADC Sampling Mode Subregister (Address 0x12) section.
2 The contents of the VIN RANGE0 and VIN RANGE1 subregisters are ignored when the AD7292 is configured to sample with respect to AVDD; the only input range
allowed when sampling with respect to AVDD is from (AVDD − 4 × VREF) to AVDD.
111...111
111...110
111...000
011...111
000...010
000...001
000...000
1LSB = V
REF
/1024
ANALOG INPUT
NOTES
1. V
REF
IS 1.25V.
2. I NP UT RANG E IS 0V TO V
REF
.
ADC CODE
+V
REF
– 1LS B1LSB
0V
10660-040
Figure 34. Straight Binary Transfer Characteristic Corresponding to Single-Ended Input Range of 0 V to VREF
Table 11. Output Codes and Ideal Input Voltages (AVDD = 5 V)
Description
Analog Input Range
Digital Output
Code (Hex)
Single-Ended Mode of Operation Differential Mode of Operation
0 V to
4 × VREF
0 V to
2 × VREF 0 V to VREF
(AVDD − 4 × VREF)
to AVDD
−4 × VREF to
+4 × VREF
−2 × VREF to
+2 × VREF −VREF to +VREF
+FSR − 1 LSB 4.995117 V 2.497559 V 1.248779 V 4.995117 V 4.990234 V 2.495117 V 1.247559 V 0x3FF
Midscale + 1 LSB 2.504883 V 1.252441 V 0.626221 V 2.504883 V 0.009766 V 0.004883 V 0.002441 V 0x201
Midscale 2.5 V 1.25 V 0.625 V 2.5 V 0 V 0 V 0 V 0x200
Midscale − 1 LSB 2.495117 V 1.247559 V 0.623779 V 2.495117 V −0.009766 V −0.004883 V −0.002441 V 0x1FF
−FSR + 1 LSB 0.004883 V 0.002441 V 0.001221 V 0.004883 V 4.995117 V −2.495117 V −1.247559 V 0x001
−FSR 0 V 0 V 0 V 0 V −5 V −2.5 V −1.25 V 0x000
Rev. A | Page 16 of 40
Data Sheet AD7292
TEMPERATURE SENSOR
The AD7292 contains one local temperature sensor. The on-chip,
band gap temperature sensor measures the temperature of the
AD7292 die. The temperature sensor input gathers data and
computes a value over a period of several hundred microseconds.
The temperature measurement takes place continuously in the
background, leaving the user free to perform conversions on the
other channels.
After a temperature value is computed, a signal passes to the
control logic to initiate a conversion automatically. If an ADC
conversion is in progress, the temperature sensor conversion is
performed as soon as the ADC conversion is completed. If the
ADC is idle, the temperature sensor conversion takes place
immediately.
The TSENSE conversion result register stores the result of the last
conversion on the temperature channel; this result can be read at
any time provided that the temperature sensor is enabled via the
temperature sensor subregister within the configuration register
bank (see the Temperature Sensor Subregister (Address 0x20)
section).
Temperature readings from the ADC are stored in the TSENSE
conversion result register. Results are in 14-bit straight binary
format and accommodate both positive and negative tempera-
ture measurements. Bit D0 and Bit D1 hold alert flags; Bit D2
stores the LSB, which corresponds to 0.03125°C if the digital
filter is enabled.
Table 12 provides examples of temperature sensor data. An output
of all 0s is equal to −256°C; this value is output by the AD7292
until the first measurement is completed. Note that when digital
filtering is disabled, Bit D3 and Bit D2 of the TSENSE conversion
result register are set to 0, producing a 12-bit straight binary result
with an LSB of 0.125°C. When the TSENSE conversion result is
read via the ADC data register (Address 0x01), the temperature
sensor result is a 10-bit result with an LSB that equates to 0.5°C.
Table 12. Temperature Sensor Data Format
Temperature (°C)
TSENSE Conversion Result Register,
Bits[D15:D2]
−40 01 1011 0000 0000
−25 01 1100 1110 0000
−10 01 1110 1100 0000
−0.03125 01 1111 1111 1111
0 10 0000 0000 0000
+0.03125 10 0000 0000 0001
+10 10 0001 0100 0000
+25 10 0011 0010 0000
+50 10 0110 0100 0000
+75 10 1001 0110 0000
+100 10 1100 1000 0000
+125 10 1111 1010 0000
DAC OPERATION
The four DACs of the AD7292 provide digital control with 10 bits
of resolution. DAC outputs VOUT0 to VOUT3 feature an output
voltage range up to 5 V (LSB of 4.88 mV).
The DAC output buffer can be controlled via software using the
GPIO2/DAC DISABLE0 and GPIO4/DAC DISABLE1 subregisters
within the configuration register bank, or via hardware using
the GPIO2/DAC DISABLE0 and GPIO4/DAC DISABLE1 pins.
DIGITAL I/O PINS
To aid in system monitoring, the AD7292 features 12 digital I/O
pins. All 12 pins can be configured as GPIO pins. Six of the digital
I/O pins can be configured for other functionality; on power-up,
the non-GPIO functionality of these six pins is enabled by default.
For more information, see the Digital Output Driver Subregister
(Address 0x01) section and the Digital I/O Function Subregister
(Address 0x02) section.
GPIO0/ALERT0 and GPIO1/ALERT1 Pins
When Pin 27 and Pin 26 (GPIO0/ALERT0 and GPIO1/ALERT1,
respectively) are configured as alert pins, they act as out-of-range
indicators that become active when the selected conversion result
exceeds the high or low limit stored in the alert limits register bank.
The polarity of the alert output pins can be set to active high or
active low via the general subregister within the configuration
register bank (see the General Subregister (Address 0x08) section).
GPIO2/DAC DISABLE0 and GPIO4/DAC DISABLE1 Pins
When Pin 25 and Pin 23 (GPIO2/DAC DISABLE0 and GPIO4/
DAC DISABLE1, respectively) are configured as DAC disable pins,
they can be used to power down the selected DAC outputs, as
determined by the contents of the GPIO2/DAC DISABLE0 and
GPIO4/DAC DISABLE1 subregisters within the configuration
register bank. For more information, see the GPIO2/DAC
DISABLE0 and GPIO4/DAC DISABLE1 Subregisters (Address
0x30 and Address 0x31) section.
GPIO3/LDAC Pin
When Pin 24 (GPIO3/LDAC) is configured as an LDAC pin,
the DAC registers are updated when this input pin is taken high.
GPIO6/BUSY Pin
Pin 21 (GPIO6/BUSY) can be configured as a general-purpose
input/output or as a busy output pin. When configured as a busy
output pin, this pin transitions high when a conversion starts
and remains high until the conversion is completed.
Rev. A | Page 17 of 40
AD7292 Data Sheet
Rev. A | Page 18 of 40
SERIAL PORT INTERFACE (SPI)
The AD7292 serial port interface (SPI) allows the user to
configure the device for specific functions and operations
through an internal structured register space. The interface
consists of four signals: CS, SCLK, DIN, and DOUT. The SPI
reference level is set by Pin 5 (VDRIVE) to a level in the range of
1.8 V to 5.25 V.
SCLK is the serial clock input for the device; all data transfers
on DIN or DOUT take place with respect to SCLK. The chip
select input pin (CS) is an active low control that initiates the
data transfer and conversion process.
Data is clocked into the AD7292 on the SCLK falling edge.
Data is loaded into the device MSB first. The length of each
frame can vary and depends on the command being sent. Data
is clocked out of the AD7292 on DOUT in the same frame as
the read command, on the rising edge of SCLK while CS is low.
When CS is high, the SCLK and DIN signals are ignored and
the DOUT line becomes high impedance.
INTERFACE PROTOCOL
When reading from or writing to the AD7292, the first byte con-
tains the address pointer (see Table 13). Bit D7 and Bit D6 of the
address pointer are the read and write bits, respectively. Bit D5 to
Bit D0 of the address pointer specify the register address for the
read or write operation. A register can be simultaneously read
from and written to by setting both Bit D7 and Bit D6 to 1.
Table 13. Address Pointer
D7 D6 D5 D4 D3 D2 D1 D0
R W Register select
After the address pointer, subsequent data for writing to the part
is supplied in bytes (see Figure 36). Some registers are located
within register banks and, therefore, require both a pointer address
and a subpointer address. The subpointer address is specified
in the first byte following the pointer address (see Figure 37).
Figure 36 through Figure 38 show the read and write data formats.
These figures show read operations; for a write to a register or
subregister, the write bit is set and the DOUT line remains high
impedance.
If neither the read nor write bit is set (Bit D7 and Bit D6 of the
address pointer are set to 0), the address pointer is updated but
no data is read or written. Note that writing this command also
reinitializes the ADC sequencer (see the ADC Conversion
Control section).
On completion of a read or write, the AD7292 is ready to accept
a new pointer address; alternatively, the CS pin can be taken high
to terminate the operation.
10660-041
RX W D5 D4 D3 D2 D1 D0 LSB X
LSB
t4
t5t6
t3t2t1
t7t8
t11
t12
t10
t9
HIGH-Z HIGH-Z
BUSY
2
CS
SCLK
DIN
DOUT
1
1
PROVIDED THE READ BIT I S SET.
2
IF AN ADC CONVERSION IS REQUES TED.
t7
= 5ns I F NO A DC CONVERS ION
955ns WITH ADC CONVE RS ION
Figure 35. Serial Interface Timing Diagram
PO INT E R [D5:D0] DIN [D1 5:D 8] DIN [D7:D0]
CS
DIN
DOUT
RW
DOUT [D15 : D0 ]
1
1
PRO V I DE D T HE RE AD BI T I S S ET.
10660-042
Figure 36. Accessing a 16-Bit Register
Data Sheet AD7292
POINT E R [ D5: D0] SUBP OINTER [D7: D0] DIN [ D7: D0]
CS
DIN
DOUT
R W
DOUT [D7:D0]
1
1
PROV IDED THE READ BIT IS SE T.
10660-043
Figure 37. Accessing an 8-Bit Subregister Within a Register Bank
POINT E R [ D5: D0] SUBPO INT E R [ D7: D0] DI N [ D15: D8] DIN [D7:D0]
CS
DIN
DOUT
R W
DOUT [D15:D0]
1
1
PROV IDED THE READ BIT IS SE T.
10660-044
Figure 38. Accessing a 16-Bit Subregister Within a Register Bank
Rev. A | Page 19 of 40
AD7292 Data Sheet
REGISTER STRUCTURE
The AD7292 contains internal registers that store conversion
results, high and low conversion limits, and information to
configure and control the device (see Figure 39). Each register
has an address; the address pointer register points to the address
when communicating with the register. Some registers and sub-
registers contain reserved bits. The AD7292 allows either a 0 or
a 1 to be written to these reserved bits.
ADDRESS
POINTER
REGISTER
SERI AL BUS INTE RFACE
DIN
SCLK
DATA
VENDO R ID
REGISTER
ADC DATA
ADC SEQ UE NCE
REGISTER
GPIO
REGISTER
CONFIGURATION
REGISTER BANK
OFFSET
REGISTER BANK
T
SENSE
CONVE RS IO N
RESULT REGISTER
ADC CONVE RS IO N
RESULT REGISTERS × 8
CONVERSION
COMMAND
DAC BUFFER
ENABLE REGISTER
DAC CHANNEL
REGISTERS × 4
ALERT LIMITS
REGISTER BANK
ALERT FLAGS
REGISTER BANK
MI NIMUM AND M AX IMUM
REGISTER BANK
DOUT
CS
10660-045
Figure 39. AD7292 Register Structure
Table 14 lists each register and specifies whether the register has
read access or read and write access.
Table 14. AD7292 Registers
Address Register Name Access1
Data
Format
0x00 Vendor ID register R Figure 36
0x01 ADC data register R Figure 36
0x03 ADC sequence register R/W Figure 36
0x05 Configuration register bank R/W Figure 38
0x06 Alert limits register bank R/W Figure 38
0x07 Alert flags register bank R/W Figure 38
0x08 Minimum and maximum
register bank
R/W Figure 38
0x09 Offset register bank R/W Figure 37
0x0A
DAC buffer enable register
R/W
Figure 36
0x0B GPIO register R/W Figure 36
0x0E Conversion command2 N/A N/A
0x10 ADC conversion result register,
Channel 0
R Figure 36
0x11 ADC conversion result register,
Channel 1
R Figure 36
0x12 ADC conversion result register,
Channel 2
R Figure 36
0x13 ADC conversion result register,
Channel 3
R Figure 36
0x14 ADC conversion result register,
Channel 4
R Figure 36
0x15 ADC conversion result register,
Channel 5
R Figure 36
0x16 ADC conversion result register,
Channel 6
R Figure 36
0x17
ADC conversion result register,
Channel 7
R
Figure 36
0x20 TSENSE conversion result register R Figure 36
0x30 DAC Channel 0 register R/W Figure 36
0x31 DAC Channel 1 register R/W Figure 36
0x32 DAC Channel 2 register R/W Figure 36
0x33 DAC Channel 3 register R/W Figure 36
1 R is read only; R/W is read/write.
2 See the ADC Conversion Command section for more information.
Rev. A | Page 20 of 40
Data Sheet AD7292
REGISTER DESCRIPTIONS
VENDOR ID REGISTER (ADDRESS 0x00)
The 16-bit, read-only vendor ID register stores the Analog
Devices vendor ID, 0x0018. The vendor ID register is provided
to identify the AD7292 to an SPI master such as a microcontroller.
ADC DATA REGISTER (ADDRESS 0x01)
The 16-bit, read-only ADC data register provides read access to
the most recent ADC conversion result. This register provides
10 bits of conversion data, four channel identifier bits, and two
alert bits (see the ADC Conversion Control section).
ADC SEQUENCE REGISTER (ADDRESS 0x03)
The 16-bit, read/write ADC sequence register allows the user to
specify a preprogrammed sequence of ADC channels for conver-
sion. The ADC converts on each of the specified ADC channels
in turn. For more information, see the ADC Conversion Control
section. Table 16 describes the register bit functions. Bit D15 is
the first bit in the data stream. On power-up, the ADC sequence
register contains all 0s by default.
Temperature sensor results can be inserted into the sequence by
writing a 1 to Bit D8 of the ADC sequence register, provided that
the temperature sensor has been enabled in the temperature
sensor subregister within the configuration register bank (see
the Temperature Sensor Subregister (Address 0x20) section).
CONFIGURATION REGISTER BANK (ADDRESS 0x05)
The configuration register bank subregisters are listed in Table 15.
On power-up, the subregisters within the configuration register
bank contain all 0s by default.
Table 15. Configuration Register Bank Subregisters
Subaddress (Hex)
Subregister Name
1
0x01 Digital output driver
0x02
Digital I/O function
0x08 General
0x10 VIN RANGE0
0x11 VIN RANGE1
0x12 ADC sampling mode
0x13 VIN filter
0x14 Conversion delay control
0x15 VIN ALERT0 routing
0x16 VIN ALERT1 routing
0x20 Temperature sensor
0x21 Temperature sensor alert routing
0x30 GPIO2/DAC DISABLE0
0x31 GPIO4/DAC DISABLE1
1 All subregisters in the configuration register bank are read/write.
Table 16. ADC Sequence Register, Bit Function Descriptions
Bits Bit Name R/W Description
[D15:D9] Reserved R/W Reserved
D8 TSENSE readback enable R/W 0 = disable TSENSE readback
1 = enable TSENSE readback
D7 ADC Channel 7 convert R/W 0 = disable conversion of Channel 7
1 = enable conversion of Channel 7
D6 ADC Channel 6 convert R/W 0 = disable conversion of Channel 6
1 = enable conversion of Channel 6
D5 ADC Channel 5 convert R/W 0 = disable conversion of Channel 5
1 = enable conversion of Channel 5
D4 ADC Channel 4 convert R/W 0 = disable conversion of Channel 4
1 = enable conversion of Channel 4
D3 ADC Channel 3 convert R/W 0 = disable conversion of Channel 3
1 = enable conversion of Channel 3
D2 ADC Channel 2 convert R/W 0 = disable conversion of Channel 2
1 = enable conversion of Channel 2
D1 ADC Channel 1 convert R/W 0 = disable conversion of Channel 1
1 = enable conversion of Channel 1
D0 ADC Channel 0 convert R/W 0 = disable conversion of Channel 0
1 = enable conversion of Channel 0
Rev. A | Page 21 of 40
AD7292 Data Sheet
Digital Output Driver Subregister (Address 0x01)
The 16-bit digital output driver subregister enables the output
drivers of the digital I/O pins. Setting Bits[D11:D0] to 1 enables
the corresponding digital I/O output driver. Six of the 12 digital
I/O pins offer mixed functionality (see Table 18). When a digital
I/O pin is configured as a GPIO pin and its output is enabled, its
value is controlled by the GPIO register (see the GPIO Register
(Address 0x0B) section).
Digital I/O Function Subregister (Address 0x02)
Six of the 12 GPIO pins offer dual functionality. To enable
standard GPIO functionality, write a 1 to the corresponding
bit in the 16-bit digital I/O subregister. To enable the alternative
functionality, write a 0 to the appropriate bit (see Table 18). For
example, to configure the GPIO6/BUSY pin as an ADC busy pin,
write a 0 to Bit D6 of Address 0x02.
Table 17. Digital Output Driver Subregister, Bit Function Descriptions
Bits Bit Name R/W Description
[D15:D12] Reserved R/W Reserved
D11 GPIO11 output R/W 0 = disable GPIO11 output driver; 1 = enable GPIO11 output driver
D10 GPIO10 output R/W 0 = disable GPIO10 output driver; 1 = enable GPIO10 output driver
D9 GPIO9 output R/W 0 = disable GPIO9 output driver; 1 = enable GPIO9 output driver
D8 GPIO8 output R/W 0 = disable GPIO8 output driver; 1 = enable GPIO8 output driver
D7 GPIO7 output R/W 0 = disable GPIO7 output driver; 1 = enable GPIO7 output driver
D6 GPIO6 output R/W 0 = disable GPIO6 output driver; 1 = enable GPIO6/BUSY output driver
D5 GPIO5 output R/W 0 = disable GPIO5 output driver; 1 = enable GPIO5 output driver
D4 GPIO4 output R/W 0 = disable GPIO4 output driver; 1 = enable GPIO4/DAC DISABLE1 output driver
D3 GPIO3 output R/W 0 = disable GPIO3 output driver; 1 = enable GPIO3/LDAC output driver
D2 GPIO2 output R/W 0 = disable GPIO2 output driver; 1 = enable GPIO4/DAC DISABLE0 output driver
D1
GPIO1 output
R/W
0 = disable GPIO1 output driver; 1 = enable GPIO1/ALERT1 output driver
D0
GPIO0 output
R/W
0 = disable GPIO0 output driver; 1 = enable GPIO1/ALERT0 output driver
Table 18. Digital I/O Function Subregister, Bit Function Descriptions
Bits Bit Name R/W Description
[D15:D12] Reserved R/W Reserved
D11 GPIO11 R/W 0 = reserved
1 = enable the GPIO11 function
D10 GPIO10 R/W 0 = reserved
1 = enable the GPIO10 function
D9 GPIO9 R/W 0 = reserved
1 = enable the GPIO9 function
D8 GPIO8 R/W 0 = reserved
1 = enable the GPIO8 function
D7
GPIO7
R/W
0 = reserved
1 = enable the GPIO7 function
D6 GPIO6/BUSY R/W 0 = enable the ADC busy output function
1 = enable the GPIO6 function
D5 GPIO5 R/W 0 = reserved
1 = enable the GPIO5 function
D4 GPIO4/DAC DISABLE1 R/W 0 = enable the DAC DISABLE1 input function
1 = enable the GPIO4 function
D3 GPIO3/LDAC R/W 0 = enable the LDAC input function
1 = enable the GPIO3 function
D2 GPIO2/DAC DISABLE0 R/W 0 = enable the DAC DISABLE0 input function
1 = enable the GPIO2 function
D1 GPIO1/ALERT1 R/W 0 = enable the ALERT1 output function
1 = enable the GPIO1 function
D0 GPIO0/ALERT0 R/W 0 = enable the ALERT0 output function
1 = enable the GPIO0 function
Rev. A | Page 22 of 40
Data Sheet AD7292
General Subregister (Address 0x08)
When the GPIO2/DAC DISABLE0 and GPIO4/DAC DISABLE1
pins are configured as DAC disable pins (via the digital I/O func-
tion subregister), Bits[D2:D1] of the 16-bit general subregister
control the power disable mode of these two pins. Table 19 shows
the four power disable modes. The GPIO2/DAC DISABLE0 and
GPIO4/DAC DISABLE1 subregisters determine which DAC out-
puts are controlled by the GPIO2/DAC DISABLE0 and GPIO4/
DAC DISABLE1 pins (see Table 29 and Table 30).
Bit D5 and Bit D4 of the general subregister are used to configure
the polarity of the ALERT output pins when the GPIO1/ALERT1
and GPIO0/ALERT0 pins are configured as alert outputs (see the
Digital Output Driver Subregister (Address 0x01) section and
the Digital I/O Function Subregister (Address 0x02) section).
Bit D8 is used to select the source of the voltage reference used
for the AD7292. When this bit is set to 1, the external reference
is used. When this bit is set to 0, the internal reference is used.
Table 19. General Subregister, Bit Function Descriptions
Bits Bit Name R/W Description
[D15:D9] Reserved R/W Reserved.
D8 Reference mode R/W This bit specifies whether the internal reference or an external reference is used.
0 = internal reference used (default).
1 = external reference used.
[D7:D6] Reserved R/W Reserved.
D5 ALERT1 polarity R/W When the GPIO1/ALERT1 pin is configured to function as an alert, this bit sets the polarity
of the ALERT1 pin.
0 = active low (default).
1 = active high.
D4 ALERT0 polarity R/W When the GPIO0/ALERT0 pin is configured to function as an alert, this bit sets the polarity
of the ALERT0 pin.
0 = active low (default).
1 = active high.
D3 Reserved R/W Reserved.
[D2:D1] DAC disable mode R/W These bits control the disable mode of the GPIO2/DAC DISABLE0 and GPIO4/DAC DISABLE1
pins when these pins are configured to function as DAC disable pins.
00 = 1 kΩ and 100 kΩ resistors in parallel to ground (default).
01 = 100 kΩ resistor to ground.
10 = 1 kΩ resistor to ground.
11 = high impedance.
D0 Reserved R/W Reserved.
Rev. A | Page 23 of 40
AD7292 Data Sheet
VIN RANGE0 and VIN RANGE1 Subregisters
(Address 0x10 and Address 0x11)
The 16-bit VIN RANGE0 and VIN RANGE1 subregisters
specify a divide-by-2 factor for each analog input channel,
VIN0 to VIN7. A divide-by-2 factor from both the VIN
RANGE0 and VIN RANGE1 subregisters can be applied to
each channel; that is, setting Bit D0 of VIN RANGE1 and Bit D0
of VIN RANGE0 enables a divide-by-4 factor for the VIN0 input
range. The settings of the VIN RANGE0 and VIN RANGE1 bits
are ignored if samples are with respect to AVDD (see the ADC
Sampling Mode Subregister (Address 0x12) section).
Table 20. VIN RANGE0 and VIN RANGE1 Subregisters, Bit Function Descriptions (Default = 0)
Bits Bit Name R/W Description
[D15:D8] Reserved R/W Reserved
D7 VIN7 range R/W Analog input range for VIN7 (see Table 21)
D6 VIN6 range R/W Analog input range for VIN6 (see Table 21)
D5 VIN5 range R/W Analog input range for VIN5 (see Table 21)
D4 VIN4 range R/W Analog input range for VIN4 (see Table 21)
D3
VIN3 range
R/W
Analog input range for VIN3 (see Table 21)
D2 VIN2 range R/W Analog input range for VIN2 (see Table 21)
D1 VIN1 range R/W Analog input range for VIN1 (see Table 21)
D0 VIN0 range R/W Analog input range for VIN0 (see Table 21)
Table 21. Analog Input Range Selection
Sample with Respect to AGND Sample with Respect to AVDD
Subregister Bit Settings Single-Ended Input Range Differential Input Range Single-Ended Input Range
VIN RANGE1 VIN RANGE0 (VIN0 to VIN7) (VIN0 and VIN1 Only) (VIN0 to VIN7)
0 0 0 V to 4 × VREF −4 × VREF to +4 × VREF (AVDD − 4 × VREF) to AVDD
0 1 0 V to 2 × VREF −2 × VREF to +2 × VREF Not applicable
1 0 0 V to 2 × VREF −2 × VREF to +2 × VREF Not applicable
1 1 0 V to VREF −VREF to +VREF Not applicable
Rev. A | Page 24 of 40
Data Sheet AD7292
ADC Sampling Mode Subregister (Address 0x12)
Table 22 lists the bit function descriptions for the 16-bit ADC
sampling mode subregister. Bit D0 allows the user to enable
differential input mode for analog input channels VIN0 and
VIN1. When enabled and converting on VIN0, the differential
input to the ADC is (VIN0, VIN1). When enabled and convert-
ing on VIN1, the differential input to the ADC is (VIN1, VIN0).
To use differential mode, Bit D0 must be set to 1.
Bits[D15:D8] specify whether the corresponding analog input,
VIN7 to VIN0, is measured with respect to AVDD or AGND.
Table 22. ADC Sampling Mode Subregister, Bit Function Descriptions (Default = 0)
Bits Bit Name R/W Description
D15 VIN7 sampling mode R/W This bit specifies whether VIN7 is measured with respect to AVDD or AGND.
0 = sample with respect to AVDD.
1 = sample with respect to AGND.
D14 VIN6 sampling mode R/W This bit specifies whether VIN6 is measured with respect to AVDD or AGND.
0 = sample with respect to AVDD.
1 = sample with respect to AGND.
D13 VIN5 sampling mode R/W This bit specifies whether VIN5 is measured with respect to AVDD or AGND.
0 = sample with respect to AVDD.
1 = sample with respect to AGND.
D12 VIN4 sampling mode R/W This bit specifies whether VIN4 is measured with respect to AVDD or AGND.
0 = sample with respect to AVDD.
1 = sample with respect to AGND.
D11 VIN3 sampling mode R/W This bit specifies whether VIN3 is measured with respect to AVDD or AGND.
0 = sample with respect to AVDD.
1 = sample with respect to AGND.
D10 VIN2 sampling mode R/W This bit specifies whether VIN2 is measured with respect to AVDD or AGND.
0 = sample with respect to AVDD.
1 = sample with respect to AGND.
D9 VIN1 sampling mode R/W This bit specifies whether VIN1 is measured with respect to AVDD or AGND.
0 = sample with respect to AVDD.
1 = sample with respect to AGND.
D8 VIN0 sampling mode R/W This bit specifies whether VIN0 is measured with respect to AVDD or AGND.
0 = sample with respect to AVDD.
1 = sample with respect to AGND.
[D7:D1] Reserved R/W Reserved.
D0 VIN0/VIN1 differential
mode
R/W This bit specifies whether VIN0 and VIN1 function as two single-ended inputs or as a
differential pair.
0 = single-ended mode.
1 = differential mode.
Rev. A | Page 25 of 40
AD7292 Data Sheet
VIN Filter Subregister (Address 0x13)
The 16-bit VIN filter subregister enables digital filtering of the
analog inputs channels. The digital filter consists of a simple
low-pass filter function to help reduce unwanted noise on dc
signals. Writing a 1 to Bits[D7:D0] in this subregister enables
digital filtering of the corresponding analog input channel (see
Table 23). On power-up, the VIN filter subregister contains all
0s by default.
Conversion Delay Control Subregister (Address 0x14)
The 16-bit conversion delay control subregister is used to delay
the start (including the sample point) of a conversion. The delay
is a count of internal ADC clocks following the falling SCLK
signal that triggers the start of a conversion.
For example, if the conversion delay control subregister holds
the value 0x0003, three ADC clocks are counted before the
ADC enters hold mode and the conversion begins. The ADC
clock has a period of 40 ns typically.
If the conversion delay control subregister is set to a nonzero
value N, the ADC waits for the programmed number of ADC
clock periods (N) after a conversion is triggered before
sampling the input. If the register holds the default value of 0,
there is no delay, and the conversion is started from the falling
SCLK that triggers the start of the conversion. When using the
conversion delay, the conversion is extended by N + 1 clocks.
Table 23. VIN Filter Subregister, Bit Function Descriptions
Bits Bit Name R/W Description
[D15:D8] Reserved R/W Reserved
D7 Enable digital filtering of VIN7 R/W 0 = disable digital filtering of VIN7
1 = enable digital filtering of VIN7
D6 Enable digital filtering of VIN6 R/W 0 = disable digital filtering of VIN6
1 = enable digital filtering of VIN6
D5 Enable digital filtering of VIN5 R/W 0 = disable digital filtering of VIN5
1 = enable digital filtering of VIN5
D4 Enable digital filtering of VIN4 R/W 0 = disable digital filtering of VIN4
1 = enable digital filtering of VIN4
D3 Enable digital filtering of VIN3 R/W 0 = disable digital filtering of VIN3
1 = enable digital filtering of VIN3
D2 Enable digital filtering of VIN2 R/W 0 = disable digital filtering of VIN2
1 = enable digital filtering of VIN2
D1 Enable digital filtering of VIN1 R/W 0 = disable digital filtering of VIN1
1 = enable digital filtering of VIN1
D0
Enable digital filtering of VIN0
R/W
0 = disable digital filtering of VIN0
1 = enable digital filtering of VIN0
Table 24. Conversion Delay Control Subregister, Bit Function Descriptions
Bits Bit Name R/W Description
[D15:D0] Delay value R/W These bits specify the 16-bit delay value (0 to 0xFFFF) before the start of a conver-
sion. The delay is a count of internal ADC clocks following the falling SCLK signal.
Rev. A | Page 26 of 40
Data Sheet AD7292
VIN ALERT0 Routing and VIN ALERT1 Routing
Subregisters (Address 0x15 and Address 0x16)
The 16-bit VIN ALERT0 and VIN ALERT1 subregisters enable
the routing of alerts from the analog input channels, VIN0 to
VIN7, to the GPIO0/ALERT0 and GPIO1/ALERT1 pins (see
Table 25 and Table 26.
For information about how to configure the GPIO0/ALERT0
and GPIO1/ALERT1 pins as alert pins, see the Digital I/O
Function Subregister (Address 0x02) section and the Digital
Output Driver Subregister (Address 0x01) section.
For information about how to enable routing of the temperature
sensor alerts, see the Temperature Sensor Alert Routing
Subregister (Address 0x21) section.
Table 25. VIN ALERT0 Routing Subregister, Bit Function Descriptions
Bits
Bit Name
R/W
Description
[D15:D8] Reserved R/W Reserved
D7
Route VIN7 alerts to
ALERT0 pin
R/W
0 = disable routing of VIN7 alerts to the ALERT0 pin
1 = enable routing of VIN7 alerts to the ALERT0 pin
D6 Route
VIN6 alerts to
ALERT0 pin R/W 0 = disable routing of VIN6 alerts
to the ALERT0 pin
1 = enable routing of VIN6 alerts
to the ALERT0 pin
D5 Route
VIN5 alerts to
ALERT0 pin R/W 0 = disable routing of VIN5 alerts
to the ALERT0 pin
1 = enable routing of VIN5 alerts
to the ALERT0 pin
D4 Route
VIN4 alerts to
ALERT0 pin R/W 0 = disable routing of VIN4 alerts
to the ALERT0 pin
1 = enable routing of VIN4 alerts
to the ALERT0 pin
D3 Route
VIN3 alerts to
ALERT0 pin
R/W 0 = disable routing of VIN3 alerts
to the ALERT0 pin
1 = enable routing of VIN3 alerts
to the ALERT0 pin
D2 Route
VIN2 alerts to
ALERT0 pin R/W 0 = disable routing of VIN2 alerts
to the ALERT0 pin
1 = enable routing of VIN2 alerts
to the ALERT0 pin
D1 Route
VIN1 alerts to
ALERT0 pin R/W 0 = disable routing of VIN1 alerts
to the ALERT0 pin
1 = enable routing of VIN1 alerts
to the ALERT0 pin
D0 Route
VIN0 alerts to
ALERT0 pin R/W 0 = disable routing of VIN0 alerts
to the ALERT0 pin
1 = enable routing of VIN0 alerts
to the ALERT0 pin
Table 26. VIN ALERT1 Routing Subregister, Bit Function Descriptions
Bits Bit Name R/W Description
[D15:D0]
Reserved
R/W
Reserved
D7 Route VIN7 alerts to
ALERT1 pin R/W 0 = disable routing of VIN7 alerts
to the ALERT1 pin
1 = enable routing of VIN7 alerts
to the ALERT1 pin
D6 Route VIN6 alerts to
ALERT1 pin R/W 0 = disable routing of VIN6 alerts
to the ALERT1 pin
1 = enable routing of VIN6 alerts
to the ALERT1 pin
D5 Route VIN5 alerts to
ALERT1 pin R/W 0 = disable routing of VIN5 alerts
to the ALERT1 pin
1 = enable routing of VIN5 alerts
to the ALERT1 pin
D4 Route VIN4 alerts to
ALERT1 pin R/W 0 = disable routing of VIN4 alerts to the ALERT1 pin
1 = enable routing of VIN4 alerts to the ALERT1 pin
D3 Route VIN3 alerts to
ALERT1 pin R/W 0 = disable routing of VIN3 alerts to the ALERT1 pin
1 = enable routing of VIN3 alerts
to the ALERT1 pin
D2 Route VIN2 alerts to
ALERT1 pin R/W 0 = disable routing of VIN2 alerts
to the ALERT1 pin
1 = enable routing of VIN2 alerts
to the ALERT1 pin
D1 Route VIN1 alerts to
ALERT1 pin R/W 0 = disable routing of VIN1 alerts to the ALERT1 pin
1 = enable routing of VIN1 alerts to the ALERT1 pin
D0 Route VIN0 alerts to
ALERT1 R/W 0 = disable routing of VIN0 alerts to the ALERT1 pin
1 = enable routing of VIN0 alerts to the ALERT1 pin
Rev. A | Page 27 of 40
AD7292 Data Sheet
Rev. A | Page 28 of 40
Temperature Sensor Subregister (Address 0x20)
The 16-bit temperature sensor subregister enables temperature
sensor conversions and digital filtering of the temperature sensor
channel. To enable temperature sensor conversions or digital
filtering, the corresponding bit in the temperature sensor sub-
register must be set to 1 (see Table 27). On power-up, the
temperature sensor subregister contains all 0s by default.
Temperature Sensor Alert Routing Subregister
(Address 0x21)
The 16-bit temperature sensor alert routing subregister enables
the routing of alerts from the internal temperature sensor to the
GPIO0/ALERT0 and GPIO1/ALERT1 pins (see Table 28).
For information about how to configure the GPIO0/ALERT0 and
GPIO1/ALERT1 pins as alert pins, see the Digital I/O Function
Subregister (Address 0x02) section and the Digital Output Driver
Subregister (Address 0x01) section.
For information about how to enable routing of the analog input
channel alerts, see the VIN Filter Subregister (Address 0x13)
and Conversion Delay Control Subregister (Address 0x14)
section.
Table 27. Temperature Sensor Subregister, Bit Function Descriptions
Bits Bit Name R/W Description
[D15:D9] Reserved R/W Reserved.
D8 Enable/disable digital
filtering of TSENSE
R/W This bit specifies whether digital filtering is enabled on the temperature sensor channel.
0 = disable digital filtering of the temperature sensor channel (default).
1 = enable digital filtering of the temperature sensor channel.
[D7:D1] Reserved R/W Reserved.
D0 Enable/disable TSENSE
conversions
R/W This bit enables or disables conversion of the temperature sensor channel.
0 = disable TSENSE conversions (default).
1 = enable TSENSE conversions.
Table 28. Temperature Sensor Alert Routing Subregister, Bit Function Descriptions
Bits Bit Name R/W Description
[D15:D9] Reserved R/W Reserved.
D8 Route TSENSE alerts to
ALERT1 pin
R/W This bit specifies whether alerts from the internal temperature sensor are routed to the
ALERT1 pin.
0 = disable routing of alerts from the temperature sensor to the ALERT1 pin (default).
1 = enable routing of alerts from the temperature sensor to the ALERT1 pin.
[D7:D1] Reserved R/W Reserved.
D0 Route TSENSE alerts to
ALERT0 pin
R/W This bit specifies whether alerts from the internal temperature sensor are routed to the
ALERT0 pin.
0 = disable routing of alerts from the temperature sensor to the ALERT0 pin (default).
1 = enable routing of alerts from the temperature sensor to the ALERT0 pin.
Data Sheet AD7292
GPIO2/DAC DISABLE0 and GPIO4/DAC DISABLE1
Subregisters (Address 0x30 and Address 0x31)
The 16-bit, read/write GPIO2/DAC DISABLE0 and GPIO4/DAC
DISABLE1 subregisters specify which DAC channels are disabled
by the GPIO2/DAC DISABLE0 and GPIO4/DAC DISABLE1 pins.
For example, when Bit D0 in the GPIO2/DAC DISABLE0 sub-
register is set to 1, the GPIO2/DAC DISABLE0 pin disables DAC
output VOUT0 when the pin is taken high. On power-up, these
subregisters contain all 0s by default.
For information about how to enable the DAC disable function
on the GPIO2/DAC DISABLE0 and GPIO4/DAC DISABLE1
pins, see the Digital Output Driver Subregister (Address 0x01)
section and the Digital I/O Function Subregister (Address 0x02)
section.
Table 29. GPIO2/DAC DISABLE0 Subregister, Bit Function Descriptions
Bits Bit Name R/W Description
[D15:D4] Reserved R/W Reserved.
D3 Disable VOUT3 pin R/W This bit specifies whether the VOUT3 output is disabled when the GPIO2/DAC DISABLE0
pin is high.
0 = disable control of VOUT3 by the GPIO2/DAC DISABLE0 pin (default).
1 = enable control of VOUT3 by the GPIO2/DAC DISABLE0 pin.
D2 Disable VOUT2 pin R/W This bit specifies whether the VOUT2 output is disabled when the GPIO2/DAC DISABLE0
pin is high.
0 = disable control of VOUT2 by the GPIO2/DAC DISABLE0 pin (default).
1 = enable control of VOUT2 by the GPIO2/DAC DISABLE0 pin.
D1 Disable VOUT1 pin R/W This bit specifies whether the VOUT1 output is disabled when the GPIO2/DAC DISABLE0
pin is high.
0 = disable control of VOUT1 by the GPIO2/DAC DISABLE0 pin (default).
1 = enable control of VOUT1 by the GPIO2/DAC DISABLE0 pin.
D0 Disable VOUT0 pin R/W This bit specifies whether the VOUT0 output is disabled when the GPIO2/DAC DISABLE0
pin is high.
0 = disable control of VOUT0 by the GPIO2/DAC DISABLE0 pin (default).
1 = enable control of VOUT0 by the GPIO2/DAC DISABLE0 pin.
Table 30. GPIO4/DAC DISABLE1 Subregister, Bit Function Descriptions
Bits Bit Name R/W Description
[D15:D4] Reserved R/W Reserved.
D3
Disable VOUT3 pin
R/W
This bit specifies whether the VOUT3 output is disabled when the GPIO4/DAC DISABLE1
pin is high.
0 = disable control of VOUT3 by the GPIO4/DAC DISABLE1 pin (default).
1 = enable control of VOUT3 by the GPIO4/DAC DISABLE1 pin.
D2 Disable VOUT2 pin R/W This bit specifies whether the VOUT2 output is disabled when the GPIO4/DAC DISABLE1
pin is high.
0 = disable control of VOUT2 by the GPIO4/DAC DISABLE1 pin (default).
1 = enable control of VOUT2 by the GPIO4/DAC DISABLE1 pin.
D1 Disable VOUT1 pin R/W This bit specifies whether the VOUT1 output is disabled when the GPIO4/DAC DISABLE1
pin is high.
0 = disable control of VOUT1 by the GPIO4/DAC DISABLE1 pin (default).
1 = enable control of VOUT1 by the GPIO4/DAC DISABLE1 pin.
D0 Disable VOUT0 pin R/W This bit specifies whether the VOUT0 output is disabled when the GPIO4/DAC DISABLE1
pin is high.
0 = disable control of VOUT0 by the GPIO4/DAC DISABLE1 pin (default).
1 = enable control of VOUT0 by the GPIO4/DAC DISABLE1 pin.
Rev. A | Page 29 of 40
AD7292 Data Sheet
ALERT LIMITS REGISTER BANK (ADDRESS 0x06)
The alert limits register bank comprises subregisters that set the
high and low alert limits for the eight analog input channels and
the temperature sensor channel (see Table 31). Each subregister
is 16 bits in length; values are 10-bit, left-justified (padded with
0s as the 6 LSBs). On power-up, the low limit and hysteresis
subregisters contain all 0s, whereas the high limit subregisters
are set to 0xFFC0.
If a conversion result exceeds the high or low limit set in the
alert limits subregister, the AD7292 signals an alert in one or
more of the following ways:
• Via hardware using the GPIO0/ALERT0 and GPIO1/ALERT1
pins (see the Hardware Alert Pins section)
• Via software using the alert flag bits in the conversion result
registers (see the ADC Conversion Result Registers, VIN0
to VIN7 (Address 0x10 to Address 0x17) section and the
TSENSE Conversion Result Register (Address 0x20) section)
• Via software using the alert bits in the alert flags register
bank (see the Alert Flags Register Bank (Address 0x07)
section)
Alert High Limit and Alert Low Limit Subregisters
The alert high limit subregisters store the upper limit that
activates an alert. If the conversion result is greater than the value
in the alert high limit subregister, an alert is triggered. The alert
low limit subregister stores the lower limit that activates an alert.
If the conversion result is less than the value in the alert low limit
subregister, an alert is triggered.
An alert associated with either the alert high limit or alert low
limit subregister is cleared automatically after the monitored
signal is back in range, that is, when the conversion result returns
between the configured high and low limits. The contents of the
alert flags subregisters are updated after each conversion (see the
Alert Flags Register Bank (Address 0x07) section).
Hysteresis Subregisters
Each channel has an associated hysteresis subregister that stores
the hysteresis value, N (see Table 31). The hysteresis subregisters
can be used to avoid flicker on the GPIO0/ALERT0 and GPIO1/
ALERT1 pins. If the hysteresis function is enabled, the conversion
result must return to a value of at least N LSB below the alert high
limit subregister value, or N LSB above the alert low limit sub-
register value for the alert output pins and alert flag bits to be reset
(see Figure 46). The value of N is taken from the 10 MSBs of the
16-bit, read/write hysteresis subregister. For more information,
see the Hysteresis section.
Table 31. Alert Limits Register Bank Subregisters
1 All subregisters in the alert limits register bank are read/write.
Subaddress (Hex) Subregister Name1
0x00 VIN0 alert high limit
0x01 VIN0 alert low limit
0x02 VIN0 hysteresis
0x03
VIN1 alert high limit
0x04 VIN1 alert low limit
0x05 VIN1 hysteresis
0x06 VIN2 alert high limit
0x07 VIN2 alert low limit
0x08 VIN2 hysteresis
0x09 VIN3 alert high limit
0x0A VIN3 alert low limit
0x0B VIN3 hysteresis
0x0C VIN4 alert high limit
0x0D VIN4 alert low limit
0x0E VIN4 hysteresis
0x0F VIN5 alert high limit
0x10 VIN5 alert low limit
0x11 VIN5 hysteresis
0x12 VIN6 alert high limit
0x13 VIN6 alert low limit
0x14
VIN6 hysteresis
0x15 VIN7 alert high limit
0x16 VIN7 alert low limit
0x17 VIN7 hysteresis
0x18 to 0x2F Reserved
0x30 TSENSE alert high limit
0x31 TSENSE alert low limit
0x32 TSENSE hysteresis
0x33 to 0xFF Reserved
Rev. A | Page 30 of 40
Data Sheet AD7292
ALERT FLAGS REGISTER BANK (ADDRESS 0x07)
If a conversion result activates an alert (as specified in the alert
limits register bank), the alert flags register bank can be read
to obtain more information about the alert. This register bank
contains the ADC alert flags and TSENSE alert flags subregisters.
Both subregisters store flags that are triggered when the mini-
mum or maximum conversion limits, as defined in the alert
limits register bank, are exceeded.
Table 32. Alert Flags Register Bank Subregisters
1 Bits in the alert flags subregisters can be reset by writing 1 to the selected bits.
ADC Alert Flags and TSENSE Alert Flags Subregisters
(Address 0x00 and Address 0x02)
The ADC alert flags subregister stores alerts for the analog volt-
age conversion channels, VIN0 to VIN7. The TSENSE alert flags
subregister stores alerts for the temperature sensor channel.
These subregisters contain two status bits per channel: one
corresponding to the high limit, and the other corresponding to
the low limit. A bit with a status of 1 shows the channel on which
the violation occurred and whether the violation occurred on the
high or low limit.
If additional alert events occur on any other channels after the
first alert is triggered but before the alert flags subregister is read,
the corresponding bits for the new alert events are also set. For
example, if Bit D14 in the ADC alert flags subregister is set to 1,
the low limit on Channel 7 has been exceeded, whereas if Bit D3
is set to 1, the high limit on Channel 1 has been exceeded.
To find out which channel or channels caused the alert flag, the
user must read the ADC alert flags subregister or the TSENSE alert
flags subregister. If the ADC alert flags subregister or the TSENSE
alert flags subregister is accessed with both the read and write bits
of the address pointer set to 1, the stored alert flags can be read
and reset in one operation. A blanket reset can be performed by
writing 0xFFFF to the ADC alert flags subregister, or 0x0003 to
the TSENSE alert flags subregister, thus clearing all alert flags.
Table 33. ADC Alert Flags Subregister, Bit Function Descriptions
Bits Bit Name R/W Description
D15 VIN7 high limit flag R/W 1 = VIN7 high limit exceeded
D14 VIN7 low limit flag R/W 1 = VIN7 low limit exceeded
D13 VIN6 high limit flag R/W 1 = VIN6 high limit exceeded
D12 VIN6 low limit flag R/W 1 = VIN6 low limit exceeded
D11 VIN5 high limit flag R/W 1 = VIN5 high limit exceeded
D10 VIN5 low limit flag R/W 1 = VIN5 low limit exceeded
D9 VIN4 high limit flag R/W 1 = VIN4 high limit exceeded
D8 VIN4 low limit flag R/W 1 = VIN4 low limit exceeded
D7 VIN3 high limit flag R/W 1 = VIN3 high limit exceeded
D6 VIN3 low limit flag R/W 1 = VIN3 low limit exceeded
D5 VIN2 high limit flag R/W 1 = VIN2 high limit exceeded
D4 VIN2 low limit flag R/W 1 = VIN2 low limit exceeded
D3 VIN1 high limit flag R/W 1 = VIN1 high limit exceeded
D2 VIN1 low limit flag R/W 1 = VIN1 low limit exceeded
D1 VIN0 high limit flag R/W 1 = VIN0 high limit exceeded
D0
VIN0 low limit flag
R/W
1 = VIN0 low limit exceeded
Table 34. TSENSE Alert Flags Subregister, Bit Function Descriptions
Bits Bit Name R/W Description
[D15:D2] Reserved R/W Reserved
D1 TSENSE high limit flag R/W 1 = TSENSE high limit exceeded
D0 TSENSE low limit flag R/W 1 = TSENSE low limit exceeded
Subaddress (Hex) Subregister Name1
0x00 ADC alert flags subregister
0x01 Reserved
0x02 TSENSE alert flags subregister
0x03 to 0xFF Reserved
Rev. A | Page 31 of 40
AD7292 Data Sheet
MINIMUM AND MAXIMUM REGISTER BANK
(ADDRESS 0x08)
The minimum and maximum register bank contains the mini-
mum and maximum conversion values for each of the eight
analog input channels and the temperature sensor channel.
Values are 10-bit, left justified.
The minimum and maximum subregisters are cleared when a
value is written to them—that is, they return to their power-up
values. This means that if a subregister is accessed with both the
read and write bits set, the stored minimum or maximum value
can be read and reset in one operation. On power-up, the mini-
mum value subregisters contain 0xFFC0, and the maximum value
subregisters contain 0x0000.
Table 35. Minimum and Maximum Register Bank Subregisters
1 Bits in the minimum and maximum subregisters can be reset by writing 1 to
the selected bits.
OFFSET REGISTER BANK (ADDRESS 0x09)
The offset register bank contains nine subregisters. Each of the
eight analog input channels, as well as the temperature sensor
channel, has a corresponding offset register (see Table 36).
Table 36. Offset Register Bank Subregisters
Subaddress (Hex) Subregister Name1
0x00 VIN0 offset
0x01 VIN1 offset
0x02 VIN2 offset
0x03 VIN3 offset
0x04 VIN4 offset
0x05 VIN5 offset
0x06 VIN6 offset
0x07 VIN7 offset
0x10 Temperature sensor offset
1 All subregisters in the offset register bank are read/write.
Each 8-bit, read/write offset subregister stores data in twos
complement format. Values are added to the ADC conversion
results. The offset encoding scheme used for the analog input
channels and the temperature sensor are shown in Table 39 and
Table 40, respectively. The default value for all subregisters in
the offset register bank is 0x00.
When bits in these subregisters are set, the offset value is cumula-
tive. Table 37 provides examples of analog input channel values,
and Table 38 provides examples of temperature sensor channel
values.
Table 37. Examples of Analog Input Channel Offset Values
Offset Subregister Value Offset Value (LSB)
10000000 −32
11000000
−16
00001000 +2
Table 38. Examples of Temperature Sensor Channel Offset
Values
Offset Subregister Value Offset Value (°C)
10000000
−16
11000000 −8
00001000 +1
Table 39. VIN0 to VIN7 Offset Encoding Scheme
D7 D6 D5 D4 D3 D2 D1 D0
−32 LSB +16 LSB +8 LSB +4 LSB +2 LSB +1 LSB +0.5 LSB +0.25 LSB
Table 40. Temperature Sensor Offset Encoding Scheme
D7 D6 D5 D4 D3 D2 D1 D0
−16°C +8°C +4°C +2°C +1°C +0.5°C +0.25°C +0.125°C
Subaddress (Hex) Subregister Name1
0x00 VIN0 maximum value
0x01 VIN0 minimum value
0x02 VIN1 maximum value
0x03 VIN1 minimum value
0x04 VIN2 maximum value
0x05 VIN2 minimum value
0x06 VIN3 maximum value
0x07 VIN3 minimum value
0x08 VIN4 maximum value
0x09 VIN4 minimum value
0x0A VIN5 maximum value
0x0B
VIN5 minimum value
0x0C VIN6 maximum value
0x0D VIN6 minimum value
0x0E VIN7 maximum value
0x0F VIN7 minimum value
0x10 to 0x1F
Reserved
0x20 TSENSE maximum value
0x21 TSENSE minimum value
0x22 to 0xFF Reserved
Rev. A | Page 32 of 40
Data Sheet AD7292
DAC BUFFER ENABLE REGISTER (ADDRESS 0x0A)
The 16-bit, read/write DAC buffer enable register enables the
DAC output buffers. Setting the appropriate bit to 1 enables the
corresponding DAC output buffer (see Table 41). On power-up,
the DAC buffer enable register contains all 0s by default.
GPIO REGISTER (ADDRESS 0x0B)
The 16-bit, read/write GPIO register is used to read or write data
to the GPIO pins, provided that the GPIO functionality is enabled
(see the Digital Output Driver Subregister (Address 0x01) section
and the Digital I/O Function Subregister (Address 0x02) section).
On power-up, the GPIO register contains all 0s by default.
Table 41. DAC Buffer Enable Register, Bit Function Descriptions
Bits Bit Name R/W Description
[D15:D4] Reserved R/W Reserved
D3 Enable DAC 3 R/W 0 = disable DAC 3 output buffer (default)
1 = enable DAC 3 output buffer
D2 Enable DAC 2 R/W 0 = disable DAC 2 output buffer (default)
1 = enable DAC 2 output buffer
D1 Enable DAC 1 R/W 0 = disable DAC 1 output buffer (default)
1 = enable DAC 1 output buffer
D0 Enable DAC 0 R/W 0 = disable DAC 0 output buffer (default)
1 = enable DAC 0 output buffer
Table 42. GPIO Register, Bit Function Descriptions
Bits Bit Name R/W Description
[D15:D12] Reserved R/W Reserved
D11 GPIO11 R/W 0 = low output for write; low input for read
1 = high output for write; high input for read
D10 GPIO10 R/W 0 = low output for write; low input for read
1 = high output for write; high input for read
D9 GPIO9 R/W 0 = low output for write; low input for read
1 = high output for write; high input for read
D8 GPIO8 R/W 0 = low output for write; low input for read
1 = high output for write; high input for read
D7 GPIO7 R/W 0 = low output for write; low input for read
1 = high output for write; high input for read
D6 GPIO6 R/W 0 = low output for write; low input for read
1 = high output for write; high input for read
D5 GPIO5 R/W 0 = low output for write; low input for read
1 = high output for write; high input for read
D4 GPIO4 R/W 0 = low output for write; low input for read
1 = high output for write; high input for read
D3
GPIO3
R/W
0 = low output for write; low input for read
1 = high output for write; high input for read
D2 GPIO2 R/W 0 = low output for write; low input for read
1 = high output for write; high input for read
D1 GPIO1 R/W 0 = low output for write; low input for read
1 = high output for write; high input for read
D0
GPIO0
R/W
0 = low output for write; low input for read
1 = high output for write; high input for read
Rev. A | Page 33 of 40
AD7292 Data Sheet
CONVERSION COMMAND REGISTER
(ADDRESS 0x0E)
The conversion command signals the ADC to begin conversions.
See the ADC Conversion Control section for more information.
ADC CONVERSION RESULT REGISTERS, VIN0 TO
VIN7 (ADDRESS 0x10 TO ADDRESS 0x17)
The 16-bit, read-only ADC conversion result registers store the
conversion results of the eight ADC input channels. Bits[D15:D6]
store the 10-bit, straight binary result; Bits[D5:D0] contain the
channel ID and alert information. Table 43 lists the contents
of the two bytes that are read from the ADC conversion result
registers. Channel ID numbers 0 to 7 correspond to the analog
input channels, VIN0 to VIN7.
TSENSE CONVERSION RESULT REGISTER
(ADDRESS 0x20)
The 16-bit, read-only TSENSE conversion result register stores the
ADC data generated from the internal temperature sensor. The
temperature data is stored in a 14-bit straight binary format. Bit D2
has a weight of 0.03125°C. An output of all 0s is equal to −256°C;
this value is output by the AD7292 until the first measurement is
completed. An output of 10 0000 0000 0000 corresponds to 0°C.
When digital filtering is disabled, Bit D3 and Bit D2 are set to 0,
producing a 12-bit straight binary result with an LSB of 0.125°C.
See the Temperature Sensor section for more information.
DAC CHANNEL REGISTERS (ADDRESS 0x30 TO
ADDRESS 0x33)
Writing to the DAC channel registers sets the DAC output voltage
codes. For more information, see the DAC Output Control section.
Table 43. ADC Conversion Result Register Format
MSB LSB
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 [D5:D2] D1 D0
B9 B8 B7 B6 B5 B4 B3 B2 B1 B0 4-bit channel ID
(0000 to 0111)
TSENSE
alert flag
ADC
alert flag
Table 44. TSENSE Conversion Result Register Format
MSB LSB
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D31 D21 D1 D0
B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0 TSENSE
alert
flag
ADC
alert
flag
1 When digital filter is enabled (see the Temperature Sensor Subregister (Address 0x20) section).
Table 45. DAC Channel Register Format
MSB LSB
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
B9 B8 B7 B6 B5 B4 B3 B2 B1 B0 0 0 0 0 Copy LDAC
Rev. A | Page 34 of 40
Data Sheet AD7292
ADC CONVERSION CONTROL
ADC CONVERSION COMMAND
To initiate an ADC conversion on a channel, the conversion
command must be written to the AD7292. The special address
pointer byte, 0x8E, consists of the conversion command register
(Address 0x0E) with the MSB read bit set to 1 to signify an
ADC conversion. When the conversion command is received,
the AD7292 uses the current value of the address pointer to
determine which channel to convert on.
In Figure 40, the first byte sets the address pointer with both the
read and write bits cleared and sets Bits[D5:D0] to point to the
selected channel conversion result register. The second byte con-
tains the conversion command with the read bit set. After receiving
the conversion command, the AD7292 stays in conversion mode,
performing a new ADC conversion at the end of each read, until
the CS (chip select) input signal is taken high.
In Figure 41, the address pointer is set to point to the ADC data
register (Address 0x01) with both the read and write bits cleared.
The conversion command is issued, and the contents of the ADC
sequence register specify the sequence of ADC channels for
conversion (see the ADC Sequencer section).
In this example, the ADC sequence register is programmed to
convert on analog input channels VIN0 and VIN1. The AD7292
stays in conversion mode and performs a new ADC conversion
at the end of each read until the CS input signal is taken high.
In the examples shown in Figure 40 and Figure 41, an SCLK
delay is inserted following the conversion command to allow
the ADC to perform the conversion before the data is read. If
temperature sensor conversions are requested, a longer delay
is necessary (see the Temperature Sensor section).
In some applications, the SPI bus master may not allow the
serial clock to be held low during a read sequence, and it may
be necessary to take CS high, as shown in Figure 42. In this
case, the CS line must remain low while the ADC conversion is
in progress to prevent possible corruption of the ADC result.
In the example shown in Figure 42, the address pointer is set
to point to the ADC data register (Address 0x01) with both the
read and write bits cleared. The conversion command is issued
with the read bit set. The CS line is taken high after the conver-
sion on VIN0 is completed. The CS line is then brought low,
and the ADC data register is pointed to with the read bit set.
The conversion result is clocked out. The conversion command
is reissued before the CS line is taken high again, and so on.
10660-046
CS
SCLK
DIN
DOUT
116 116 116
POINT T O CHANNEL
FO R CONVERSIO N
CONVERSION RESULT FOR
SEL E CTED CHANNE L [D15:D0]
BUSY
CONVERSION RESULT FOR
SEL E CTED CHANNE L [D15:D0]
CONVERT
SELECTED
CHANNEL
CONVERT
SELECTED
CHANNEL
CONVERT
SELECTED
CHANNEL
ISSUE CO NVERSIO N
COMMAND
8
NOTES
1. CS CANNOT BE TAKEN HI GH UNTIL AFTE R A CHANNE L CO NV E RSIO N HAS TAKEN PLACE O R WHEN BUSY IS HI GH.
Figure 40. ADC Conversion Command (ADC Sequencer Not Used)
CS
SCLK
DIN
DOUT VIN0 RES ULT
[D15:D0] V IN1 RESULT
[D15:D0]
BUSY CONVERT
VIN0 CONVERT
VIN1 CONVERT
VIN0
POINT T O ADC
DATA REG ISTER ISSUE CO NVERSIO N
COMMAND
10660-047
116 1 8 16
8116
8
NOT E 2
NOTES
1. CS CANNOT BE TAKEN HI GH UNTIL AFTE R A CHANNE L CO NV E RS I ON HAS TAKEN PLACE O R WHEN BUSY IS HI GH.
2. TEMP S E NS OR CONV E RS IONS TAKE PLACE EACH 1.25ms AFTER THE NEX T CHANNEL CONVERS ION.
Figure 41. ADC Conversion Command (ADC Sequencer Used)
Rev. A | Page 35 of 40
AD7292 Data Sheet
CS
SCLK
DIN
DOUT
BUSY
CONVERT
VIN0 CONVERT
VIN1
10660-048
VIN0 RES ULT
[D15:D0] VI N1 RESUL T
[D15:D0]
POI NT TO
ADC DATA
REGISTER
POI NT TO
ADC DATA
REGISTER
ISSUE
CONVERSION
COMMAND
ISSUE
CONVERSION
COMMAND
POI NT TO
ADC DATA
REGISTER
116
8116 24 32
8116 24
8
Figure 42. ADC Conversion Command (CS Line Taken High After Conversions)
CS
SCLK
DIN
DOUT
CONVE RSIO N RESUL T F OR VI N0
[D15:D0]
CONVE RSIO N RESUL T F OR VI N1
[D15:D0] CO NVERS IO N RESUL T F OR VI N2
[D15:D0]
BUSY
CS
SCLK
DIN
DOUT
BUSY
CONVERT
VIN0
CONVERT
VIN2
CONVERT
VIN1
POINT TO ADC
SEQUENCE
REGISTER
POINT TO ADC
DATA
REGISTER ISSUE CONVERSI ON
COMMAND
WRITE TO ADC
SEQUENCE REG ISTER [D15:D0]
116
8
116
8116
8
24 40 1 8
32 16
10660-049
Figure 43. Example of Using the ADC Sequencer
ADC SEQUENCER
The AD7292 provides an ADC sequencer, which enables the
selection of a preprogrammable sequence of channels for con-
version. Figure 43 shows the operation of the ADC sequencer.
To initiate a write to the ADC sequence register (Address 0x03),
point to it in the address pointer register with the write bit set
and the read bit cleared. The next two bytes specify the sequence
of channels that the ADC converts on (see Table 16). The ADC
data register (Address 0x01) is then pointed to and the conver-
sion command is issued. Note that the read bit is set when issuing
the conversion command.
When the ADC sequencer is used, ADC conversions are trig-
gered based on the contents of the ADC sequence register; the
address pointer reverts to its previous value—in this example,
the ADC data register—allowing the conversion results to be
read back.
After the first ADC conversion is complete, the first result is read
back, which requires 16 serial clocks. The first 10 bits contain
the ADC result, the next four bits are the channel identifier, and
the last two bits are alert bits (see Table 43). On the last falling
edge of the clock, the next ADC conversion begins.
The AD7292 continues converting on the channels specified by
the ADC sequence register. On completing the first sequence of
conversions, the sequencer loops back and begins the sequence
again until CS is taken high. The AD7292 is ready to accept a new
address pointer after CS is taken low. It is recommended that the
serial clock be kept low during the ADC conversions to ensure
that there is no disturbance of the results.
Rev. A | Page 36 of 40
Data Sheet AD7292
DAC OUTPUT CONTROL
To set the DAC output voltage codes, the user must write to the
DAC channel registers (Address 0x30 to Address 0x33). Figure 44
shows an example of how to set the DAC output voltage codes.
1. The DAC buffer enable register (Address 0x0A) is pointed
to with the write bit set.
2. The following two bytes specify which of the four DAC
output buffers are enabled.
3. The DAC channel register (DAC Channel 0 register in
Figure 44) is pointed to with the write bit set.
4. The following two bytes contain the value to be written to
the DAC channel.
On completion of this write, the DAC channel output is imme-
diately updated to the new value, provided that the LDAC bit in
the DAC channel register is not set.
Note that the process can be reversed—that is, the user can first
write a value to the DAC channel register and then enable the
DAC output buffer.
LDAC OPERATION
A write to a DAC channel register (Address 0x30 to Address 0x33)
is addressed to the DAC input register; a read from a DAC channel
register is addressed to the DAC output register (see Figure 45).
The DAC output registers are updated based on the LDAC bit in
the DAC channel register or on the polarity of the GPIO3/LDAC
pin (if the pin is configured as an LDAC pin).
When the LDAC bit in the DAC channel register is set to 1, the
10-bit DAC value is stored, but the DAC channel output is not
updated. When a write to any DAC channel register occurs with
the LDAC bit cleared, all DAC channel outputs are updated with
the stored values from previous writes.
When the LDAC bit in the DAC channel register is used to control
the updating of the DAC output, the LDAC pin function should
be disabled, that is, the GPIO3/LDAC pin should be configured
as GPIO3.
The GPIO3/LDAC pin can be used to update the DAC outputs
with the stored values when the pin is configured as an LDAC
pin (see the Digital Output Driver Subregister (Address 0x01)
section and the Digital I/O Function Subregister (Address 0x02)
section). If the GPIO3/LDAC pin is configured as an LDAC
input and is taken high, the DAC output registers are updated;
conversely, if this input pin is held low, the DAC value is stored
but the channel output is not updated.
SIMULTANEOUS UPDATE OF ALL DAC OUTPUTS
It may be useful to update all four DAC channel registers
simultaneously with the same value but not update the DAC
outputs (LDAC bit is set to 1; LDAC pin is set to 0). Setting
the copy bit (Bit 1) when writing to any DAC channel register
instructs the AD7292 to copy the new DAC value to all the DAC
input registers.
CS
SCLK
DIN
POINT TO DAC
BUFFER ENABLE
REGISTER
POINT TO DAC
CHANNEL 0
REGISTER
WRI T E T O DAC
BUFFER ENABLE REGISTER [ D1 5 : D0 ] WRITE TO DAC
CHANNEL 0 REGISTER [ D1 5 :D0]
1824 48
32
10660-050
Figure 44. Setting the DAC Output Voltage Code
DAC INPUT REGIS TER
DAC CHANNEL REGIST E R ( 0x30 TO 0x33)
READ
WRITE
SCLK
LDAC BI T
GPIO3/LDAC PIN1
1PROVIDED THE GPIO3/LDAC PIN IS CONFIGUREDAS AN LDAC PI N.
DAC OUT P UT REGIS TER DAC VOUTx
10660-051
Figure 45. DAC Input and Output Registers
Rev. A | Page 37 of 40
AD7292 Data Sheet
Rev. A | Page 38 of 40
ALERTS AND LIMITS
ALERT LIMIT MONITORING FEATURES
The alert limits register bank comprises subregisters that set the
high and low alert limits for the eight analog input channels and
the temperature sensor channel (see Table 31). Each subregister
is 16 bits in length; values are 10-bit, left-justified (padded with
0s as the 6 LSBs). On power-up, the low limit and hysteresis sub-
registers contain all 0s, whereas the high limit subregisters are
set to 0xFFC0.
The alert high limit subregisters store the upper limit that
activates an alert. If the conversion result is greater than the value
in the alert high limit subregister, an alert is triggered. The alert
low limit subregister stores the lower limit that activates an alert.
If the conversion result is less than the value in the alert low limit
subregister, an alert is triggered.
If a conversion result exceeds the high or low limit set in the
alert limits subregister, the AD7292 signals an alert in one or
more of the following ways:
Via hardware using the GPIO0/ALERT0 and GPIO1/
ALERT1 pins
Via software using the alert flag bits in the conversion
result registers
Via software using the alert bits in the alert flags register
bank
Hysteresis
The hysteresis value determines the reset point for the alert pins
and alert flags if a violation of the limits occurs. Each channel has
an associated hysteresis subregister that stores the hysteresis
value, N (see Table 31). If the hysteresis function is enabled, the
conversion result must return to a value of at least N LSB below
the alert high limit subregister value, or N LSB above the alert
low limit subregister value to reset the alert output pins and the
alert flag bits (see Figure 46).
The advantage of using the hysteresis subregister associated with
each limit subregister is that hysteresis prevents chatter on the
alert bits associated with each ADC channel and also prevents
flicker on the alert output pins. Figure 46 shows the limit check-
ing operation.
HARDWARE ALERT PINS
Pin 27 and Pin 26 (GPIO0/ALERT0 and GPIO1/ALERT1,
respectively) can be configured as alert pins (see the Digital I/O
Function Subregister (Address 0x02) section). When these pins
are configured as alert pins, they become active when the selected
conversion result exceeds the high or low limit stored in the alert
limits register bank. The polarity of the alert output pins can be
set to active high or active low via the general subregister within
the configuration register bank (see the General Subregister
(Address 0x08) section).
If an alert pin signals an alert event and the contents of the alert
flags subregisters are not read before the next conversion is com-
pleted, the contents of the subregister may change if the out-of-
range signal returns to the specified range. In this case, the ALERTx
pin no longer signals the occurrence of an alert event.
ALERT FLAG BITS IN THE CONVERSION RESULT
REGISTERS
The TSENSE alert and ADC alert flag bits in the ADC conversion
result and TSENSE conversion result registers indicate whether the
conversion result being read or any other channel result has
violated the limit registers associated with it. If an alert occurs
and the alert bit is set in a conversion result register, the master
can read the alert flags register bank to obtain more information
about where the alert occurred.
HIG H L IMI T
LOW LIMIT
HIGH LIMIT – HYSTERESIS
LOW L I MIT + HYSTERESIS
TIME
INPUT SIGNAL
ALER T S I G NAL
10660-052
Figure 46. Limit Checking: Alert High Limit, Alert Low Limit, and Hysteresis
Data Sheet AD7292
ALERT FLAGS REGISTER BANK
The alert flags register bank contains two subregisters: the ADC
alert flags subregister and the TSENSE alert flags subregister. The
ADC alert flags subregister stores alerts for the analog voltage
conversion channels, VIN0 to VIN7. The TSENSE alert flags sub-
register stores alerts for the temperature sensor channel. These
subregisters contain two status bits per channel: one correspond-
ing to the high limit, and the other corresponding to the low
limit (see Table 33 and Table 34). A bit with a status of 1 shows
the channel on which the violation occurred and whether the
violation occurred on the high or low limit.
If additional alert events occur on any other channels after the
first alert is triggered but before the alert flags subregister is read,
the corresponding bits for the new alert events are also set. For
example, if Bit D14 in the ADC alert flags subregister is set to 1,
the low limit on Channel 7 has been exceeded, whereas if Bit D3
is set to 1, the high limit on Channel 1 has been exceeded.
An alert associated with either the alert high limit or alert low
limit subregister is cleared automatically after the monitored
signal is back in range, that is, when the conversion result returns
between the configured high and low limits. The contents of the
alert flags subregister are updated after each conversion.
To find out which channel or channels caused the alert flag, the
user must read the ADC alert flags subregister or the TSENSE alert
flags subregister. If the ADC alert flags subregister or the TSENSE
alert flags subregister is accessed with both the read and write bits
of the address pointer set to 1, the stored alert flags can be read
and reset in one operation. A blanket reset can be performed by
writing 0xFFFF to the ADC alert flags subregister, or 0x0003 to
the TSENSE alert flags subregister, thus clearing all alert flags.
MINIMUM AND MAXIMUM CONVERSION RESULTS
The read-only minimum/maximum register bank contains the
minimum and maximum conversion values for each of the eight
analog input channels and the temperature sensor channel.
Values are 10-bit, left justified.
The minimum and maximum subregisters are cleared when a
value is written to them—that is, they return to their power-up
values. This means that if a subregister is accessed with both the
read and write bits set, the stored minimum or maximum value
can be read and reset in one operation. On power-up, the mini-
mum value subregisters contain 0xFFC0, and the maximum value
subregisters contain 0x0000.
Rev. A | Page 39 of 40
AD7292 Data Sheet
Rev. A | Page 40 of 40
OUTLINE DIMENSIONS
1
0.50
BSC
BOTTOM VIEWTOP VIEW
PIN 1
INDI
C
ATOR
36
1018
19
27
28
9
EXPOSED
PAD
PIN 1
INDICATOR
SEATING
PLANE
0.05 MAX
0.02 NOM
0.20 REF
COPLANARITY
0.08
0.30
0.23
0.18
6.10
6.00 SQ
5.90
0.80
0.75
0.70
FOR PRO PER CONNECT IO N OF
THE EXPOSED PAD, REFER TO
THE P IN CONFIGURATION AND
FUNCTION DES CRIPTIONS
SECTION OF T HIS DATA SHEET.
0.70
0.60
0.40
0.25 MIN
4.05
3.90 SQ
3.85
COM P LI ANT T O JEDE C STANDAR DS M O-220-WJJD.
03-29-2012-A
Figure 47. 36-Lead Lead Frame Chip Scale Package [LFCSP_WQ]
6 mm × 6 mm Body, Very Very Thin Quad
(CP-36-3)
Dimensions shown in millimeters
ORDERING GUIDE
Model1 Temperature Range Package Description Package Option
AD7292BCPZ −40°C to +125°C 36-Lead Lead Frame Chip Scale Package [LFCSP_WQ] CP-36-3
AD7292BCPZ-RL −40°C to +125°C 36-Lead Lead Frame Chip Scale Package [LFCSP_WQ] CP-36-3
EVAL-AD7292SDZ Evaluation Board
EVAL-SDP-CB1Z System Development Platform
1 Z = RoHS Compliant Part.
©2012–2014 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D10660-0-9/14(A)
