±250°/sec Yaw Rate Gyro
ADXRS612
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.461.3113 ©2007 Analog Devices, Inc. All rights reserved.
FEATURES
Complete rate gyroscope on a single chip
Z-axis (yaw rate) response
High vibration rejection over wide frequency
2000 g powered shock survivability
Ratiometric to referenced supply
5 V single-supply operation
105°C operation
Self-test on digital command
Ultrasmall and light (<0.15 cc, <0.5 gram)
Temperature sensor output
RoHS compliant
APPLICATIONS
Vehicle chassis rollover sensing
Inertial measurement units
Platform stabilization
GENERAL DESCRIPTION
The ADXRS612 is a complete angular rate sensor (gyroscope)
that uses the Analog Devices, Inc. surface-micromachining
process to make a functionally complete and low cost angular
rate sensor integrated with all of the required electronics on one
chip. The manufacturing technique for this device is the same
high volume BIMOS process used for high reliability automotive
airbag accelerometers.
The output signal, RATEOUT (1B, 2A), is a voltage propor-
tional to angular rate about the axis normal to the top surface
of the package. The output is ratiometric with respect to a provided
reference supply. A single external resistor can be used to lower
the scale factor. An external capacitor is used to set the bandwidth.
Other external capacitors are required for operation.
A temperature output is provided for compensation techniques.
Two digital self-test inputs electromechanically excite the sensor
to test proper operation of both the sensor and the signal condi-
tioning circuits. The ADXRS612 is available in a 7 mm × 7 mm ×
3 mm BGA chip-scale package.
FUNCTIONAL BLOCK DIAGRAM
V
DD
AGND
PGND
AV
CC
ST2 ST1 TEMP V
RATIO
CP1 CP2 CP3 CP4 CP5 SUMJ RATEOUT
DEMOD
180kΩ ±1%
22nF
100nF
22nF
100nF
100nF
100nF
DRIVE
AMP
MECHANICAL
SENSOR
CHARGE PUMP
AND VOLTAGE
REGULATOR
C
OUT
+5V
+5V
+5
V
(ADC REF)
AC
AMP
VGA
25kΩ
@ 25°C
ADXRS612
25kΩ
SELF-TEST
06521-001
Figure 1.
ADXRS612
Rev. 0 | Page 2 of 12
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
General Description......................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 4
Rate Sensitive Axis ....................................................................... 4
ESD Caution.................................................................................. 4
Pin Configuration and Function Descriptions............................. 5
Typical Performance Characteristics ............................................. 6
Theory of Operation .........................................................................9
Setting Bandwidth.........................................................................9
Temperature Output and Calibration.........................................9
Calibrated Performance................................................................9
ADXRS612 and Supply Ratiometricity ................................... 10
Null Adjustment ......................................................................... 10
Self-Test Function ...................................................................... 10
Continuous Self-Test.................................................................. 10
Outline Dimensions ....................................................................... 11
Ordering Guide .......................................................................... 11
REVISION HISTORY
3/07—Revision 0: Initial Version
ADXRS612
Rev. 0 | Page 3 of 12
SPECIFICATIONS
All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed. TA = −40°C to +105°C, VS = AVCC =
VDD = 5 V, VRATIO = AVCC, angular rate = 0°/sec, bandwidth = 80 Hz (COUT = 0.01 µF), IOUT = 100 µA, ±1 g, unless otherwise noted.
Table 1.
ADXRS612BBGZ
Parameter Conditions Min Typ Max Unit
SENSITIVITY1Clockwise rotation is positive output
Measurement Range2Full-scale range over specifications range ±250 ±300 °/sec
Initial and Over Temperature −40°C to +105°C 6.2 7.0 7.8 mV/°/sec
Temperature Drift3 ±2 %
Nonlinearity Best fit straight line 0.1 % of FS
NULL1
Null −40°C to +105°C 2.15 2.5 2.85 V
Linear Acceleration Effect Any axis 0.1 °/sec/g
NOISE PERFORMANCE
Rate Noise Density TA ≤ 25°C 0.06 °/sec/√Hz
FREQUENCY RESPONSE
Bandwidth4 0.01 2500 Hz
Sensor Resonant Frequency 12 14.5 17 kHz
SELF-TEST1
ST1 RATEOUT Response ST1 pin from Logic 0 to Logic 1 −750 −525 −300 mV
ST2 RATEOUT Response ST2 pin from Logic 0 to Logic 1 300 525 750 mV
ST1 to ST2 Mismatch5 −5 +5 %
Logic 1 Input Voltage 3.3 V
Logic 0 Input Voltage 1.7 V
Input Impedance To common 40 50 100 kΩ
TEMPERATURE SENSOR1
VOUT at 25°C Load = 10 MΩ 2.35 2.5 2.65 V
Scale Factor6@ 25°C, VRATIO = 5 V 9 mV/°C
Load to VS 25 kΩ
Load to Common 25 kΩ
TURN-ON TIME Power on to ±½°/sec of final 50 ms
OUTPUT DRIVE CAPABILITY
Current Drive For rated specifications 200 μA
Capacitive Load Drive 1000 pF
POWER SUPPLY
Operating Voltage (VS) 4.75 5.00 5.25 V
Quiescent Supply Current 3.5 4.5 mA
TEMPERATURE RANGE
Specified Performance −40 +105 °C
1 Parameter is linearly ratiometric with VRATIO.
2 Measurement range is the maximum range possible, including output swing range, initial offset, sensitivity, offset drift, and sensitivity drift at 5 V supplies.
3 From +25°C to −40°C or +25°C to +105°C.
4 Adjusted by external capacitor, COUT. Reducing bandwidth below 0.01 Hz does not result in further noise improvement.
5 Self-test mismatch is described as (ST2 + ST1)/((ST2 − ST1)/2).
6 Scale factor for a change in temperature from 25°C to 26°C. VTEMP is ratiometric to VRATIO. See the Temperature Output and Calibration section for more information.
ADXRS612
Rev. 0 | Page 4 of 12
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Rating
Acceleration (Any Axis, 0.5 ms)
Unpowered 2000 g
Powered 2000 g
VDD, AVCC –0.3 V to +6.0 V
VRATIO AVCC
ST1, ST2 AVCC
Output Short-Circuit Duration
(Any Pin to Common)
Indefinite
Operating Temperature Range −55°C to +125°C
Storage Temperature Range −65°C to +150°C
Stresses above those listed under the 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.
Drops onto hard surfaces can cause shocks of greater than
2000 g and can exceed the absolute maximum rating of the
device. Care should be exercised in handling to avoid damage.
RATE SENSITIVE AXIS
This is a Z-axis rate-sensing device (also called a yaw rate-
sensing device). It produces a positive going output voltage
for clockwise rotation about the axis normal to the package
top, that is, clockwise when looking down at the package lid.
RATE
AXIS
LONGITUDINAL
AXIS
LATERAL AXIS
+
ABCD G
1
7
EF
A1
RATE OUT
RATE IN
4.75V
0.25V
V
CC
= 5V
V
RATIO
/2
GND
06521-002
Figure 2. RATEOUT Signal Increases with Clockwise Rotation
ESD CAUTION
ADXRS612
Rev. 0 | Page 5 of 12
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
PGND
ST1
ST2
TEMP
A
GND V
RATIO
NC SUMJ RATEOUT
AV
CC
CP2
CP1
CP4
CP3CP5
V
DD
GF E D C BA
7
6
5
4
3
2
1
06521-023
Figure 3. Pin Configuration
Table 3. Pin Function Descriptions
Pin No. Mnemonic Description
6D, 7D CP5 HV Filter Capacitor, 0.1 μF.
6A, 7B CP4 Charge Pump Capacitor, 22 nF.
6C, 7C CP3 Charge Pump Capacitor, 22 nF.
5A, 5B CP1 Charge Pump Capacitor, 22 nF.
4A, 4B CP2 Charge Pump Capacitor, 22 nF.
3A, 3B AVCC Positive Analog Supply.
1B, 2A RATEOUT Rate Signal Output.
1C, 2C SUMJ Output Amp Summing Junction.
1D, 2D NC No Connection.
1E, 2E VRATIO Reference Supply for Ratiometric Output.
1F, 2G AGND Analog Supply Return.
3F, 3G TEMP Temperature Voltage Output.
4F, 4G ST2 Self-Test for Sensor 2.
5F, 5G ST1 Self-Test for Sensor 1.
6G, 7F PGND Charge Pump Supply Return.
6E, 7E VDD Positive Charge Pump Supply.
ADXRS612
Rev. 0 | Page 6 of 12
TYPICAL PERFORMANCE CHARACTERISTICS
N > 1000 for all typical performance plots, unless otherwise noted.
16
0
2
4
6
8
10
12
14
2.20
2.25
2.30
2.35
2.40
2.50
2.45
2.55
2.60
2.65
2.70
2.75
2.80
% OF POPULATION
VOLTS
0
6521-003
Figure 4. Null Output at 25°C (VRATIO = 5 V)
25
0
5
10
15
20
–0.30
–0.25
–0.20
–0.15
–0.10
0
–0.05
0.05
0.10
0.15
0.20
0.25
0.30
% OF POPULATION
(°/sec/°C)
06521-004
Figure 5. Null Drift over Temperature (VRATIO = 5 V)
30
0
5
10
15
20
25
6.36.46.56.66.76.86.97.07.17.27.37.47.57.67.7
% OF POPULATION
(mV/°/sec)
06521-005
Figure 6. Sensitivity at 25°C (VRATIO = 5 V)
25
0
5
10
15
20
–7 –5 –4–6 –3 –2 –1 0 1 2 3 4 5 6 7
% OF POPULATION
% DRIFT
06521-006
Figure 7. Sensitivity Drift over Temperature
45
40
35
30
25
0
5
10
15
20
–675 –625 –575 –525 –425–475 –375
% OF POPULATION
(mV)
06521-007
Figure 8. ST1 Output Change at 25°C (VRATIO = 5 V)
45
40
35
30
25
0
5
10
15
20
375 425 450400 475 500 525 550 600 625575 650 675
% OF POPULATION
(mV)
06521-008
Figure 9. ST2 Output Change at 25°C (VRATIO = 5 V)
ADXRS612
Rev. 0 | Page 7 of 12
50
45
40
35
30
25
0
5
10
15
20
–5 –4 –3 –2 –1 1 2 3 4 50
% OF POPULATION
% MISMATCH
06521-009
Figure 10. Self-Test Mismatch at 25°C (VRATIO = 5 V)
600
400
200
0
–600
–400
–200
–40 –20 0 20 40 80 100 12060
(mV)
TEMPERATURE (°C)
06521-010
–800
800
ST1
ST2
Figure 11. Typical Self-Test Change over Temperature
40
35
30
25
0
5
10
15
20
3.0 3.1 3.2 3.3 3.4 3.5 3.7 3.8 3.9 4.0 4.13.6
% OF POPULATION
(mA)
06521-011
Figure 12. Current Consumption at 25°C (VRATIO = 5 V)
40
35
30
25
0
5
10
15
20
2.40 2.42 2.44 2.46 2.48 2.50 2.54 2.56 2.58 2.602.52
% OF POPULATION
VOLTS
06521-012
Figure 13. VTEMP Output at 25°C (VRATIO = 5 V)
3.3
3.1
2.9
2.7
1.5
2.1
1.9
1.7
2.3
2.5
–40 –20 0 20 40 60 100 12080
VOLTS
TEMPERATURE (°C)
256 PARTS
06521-013
Figure 14. VTEMP Output over Temperature, 256 Parts (VRATIO = 5 V)
60
50
30
40
10
20
–20
–10
0
750 770 810 830 850790
g OR °/se
c
TIME (ms)
Y
REF
X
+45°
–45°
06521-014
Figure 15. g and g × g Sensitivity for a 50 g, 10 ms Pulse
ADXRS612
Rev. 0 | Page 8 of 12
1.6
0
100 10k
(Hz)
(°/sec)
1k
1.4
1.2
1.0
0.8
0.4
0.2
0.6
LONG
LAT
RATE
06521-015
Figure 16. Typical Response to 10 g Sinusoidal Vibration
(Sensor Bandwidth = 2 kHz)
400
300
200
100
0
–100
–200
–300
–400
02
50150100 20050
(ms)
(°/sec)
DUT1 OFFSET BY +200°/sec
DUT2 OFFSET BY –200°/sec
06521-016
Figure 17. Typical High g (2500 g) Shock Response
(Sensor Bandwidth = 40 Hz)
1
0.1
0.01
0.001
0.01 0.1 100k10k1k100101
AVERAGING TIME (Seconds)
(°/sec rms)
06521-017
Figure 18. Typical Root Allan Deviation at 25°C vs. Averaging Time
0.10
–0.05
0
0.05
–0.10
0 14012010080604020
TIME (Hours)
(°/sec)
06521-018
Figure 19. Typical Shift in 90 sec Null Averages Accumulated over 140 Hours
0.10
0.05
0
–0.05
–0.10
0 360018001200 30002400600
TIME (Seconds)
(°/sec)
06521-019
Figure 20. Typical Shift in Short Term Null (Bandwidth = 1 Hz)
0.1
0.001
0.01
0.0001
10 100k1k100
(Hz)
(°/sec/ Hz rms)
10k
06521-020
Figure 21. Typical Noise Spectral Density (Bandwidth = 40 Hz)
ADXRS612
Rev. 0 | Page 9 of 12
THEORY OF OPERATION
The ADXRS612 operates on the principle of a resonator gyro.
Two polysilicon sensing structures each contain a dither frame
that is electrostatically driven to resonance, producing the neces-
sary velocity element to produce a Coriolis force during angular
rate. At two of the outer extremes of each frame, orthogonal to
the dither motion, are movable fingers that are placed between
fixed pickoff fingers to form a capacitive pickoff structure that
senses Coriolis motion. The resulting signal is fed to a series of
gain and demodulation stages that produce the electrical rate
signal output. The dual-sensor design rejects external g-forces and
vibration. Fabricating the sensor with the signal conditioning
electronics preserves signal integrity in noisy environments.
The electrostatic resonator requires 18 V to 20 V for operation.
Because only 5 V are typically available in most applications,
a charge pump is included on-chip. If an external 18 V to 20 V
supply is available, the two capacitors on CP1 to CP4 can be
omitted, and this supply can be connected to CP5 (Pin 6 D,
Pin 7D). CP5 should not be grounded when power is applied to
the ADXRS612. No damage occurs, but under certain conditions
the charge pump may fail to start up after the ground is removed
without first removing power from the ADXRS612.
SETTING BANDWIDTH
External Capacitor COUT is used in combination with the on-
chip ROUT resistor to create a low-pass filter to limit the bandwidth
of the ADXRS612 rate response. The −3 dB frequency set by
ROUT and COUT is
(
)
OUTOUTOUT CRf ×××= π2/1
and can be well controlled because ROUT has been trimmed
during manufacturing to be 180 kΩ ± 1%. Any external resistor
applied between the RATEOUT pin (1B, 2A) and SUMJ pin
(1C, 2C) results in
(
)
(
)
EXTEXTOUT RRR +×= k180/k180
In general, an additional filter (in either hardware or software)
is added to attenuate high frequency noise arising from demodu-
lation spikes at the 14 kHz resonant frequency of the gyro. The
noise spikes at 14 kHz can be clearly seen in the power spectral
density curve, shown in Figure 21. Normally, this additional
filter corner frequency is set to greater than five times the
required bandwidth to preserve good phase response.
Figure 22 shows the effect of adding a 250 Hz filter to the
output of an ADXRS612 set to 40 Hz bandwidth (as shown
in Figure 21). High frequency demodulation artifacts are
attenuated by approximately 18 dB.
0.1
0.01
0.000001
0.00001
0.0001
0.001
10 100k1k100
(Hz)
(°/sec/ Hz rms)
10k
0
6521-021
Figure 22. Noise Spectral Density with Additional 250 Hz Filter
TEMPERATURE OUTPUT AND CALIBRATION
It is common practice to temperature-calibrate gyros to improve
their overall accuracy. The ADXRS612 has a temperature propor-
tional voltage output that provides input to such a calibration
method. The temperature sensor structure is shown in Figure 23.
The temperature output is characteristically nonlinear, and any
load resistance connected to the TEMP output results in decreasing
the TEMP output and its temperature coefficient. Therefore,
buffering the output is recommended.
The voltage at TEMP (3F, 3G) is nominally 2.5 V at 25°C, and
VRATIO = 5 V. The temperature coefficient is ~9 mV/°C at 25°C.
Although the TEMP output is highly repeatable, it has only
modest absolute accuracy.
V
RATIO
V
TEMP
R
FIXED
R
TEMP
0
6521-022
Figure 23. ADXRS612 Temperature Sensor Structure
CALIBRATED PERFORMANCE
Using a 3-point calibration technique, it is possible to calibrate
the ADXRS612 null and sensitivity drift to an overall accuracy
of nearly 200°/hour. An overall accuracy of 40°/hour or better
is possible using more points. Limiting the bandwidth of the
device reduces the flat-band noise during the calibration process,
improving the measurement accuracy at each calibration point.
ADXRS612
Rev. 0 | Page 10 of 12
ADXRS612 AND SUPPLY RATIOMETRICITY
The ADXRS612 RATEOUT and TEMP signals are ratiometric
to the VRATIO voltage; that is, the null voltage, rate sensitivity, and
temperature outputs are proportional to VRATIO. So the ADXRS612
is most easily used with a supply-ratiometric analog-to-digital
converter, which results in self-cancellation of errors due to minor
supply variations. There is some small error due to nonratiometric
behavior. Typical ratiometricity error for null, sensitivity, self-test,
and temperature output is outlined in Table 4.
Note that VRATIO must never be greater than AVCC.
Table 4. Ratiometricity Error for Various Parameters
Parameter VS = VRATIO = 4.75 V VS = VRATIO = 5.25 V
ST1
Mean −0.4% −0.3%
Sigma 0.6% 0.6%
ST2
Mean −0.4% −0.3%
Sigma 0.6% 0.6%
Null
Mean −0.04% −0.02%
Sigma 0.3% 0.2%
Sensitivity
Mean 0.03% 0.1%
Sigma 0.1% 0.1%
VTEMP
Mean −0.3% −0.5%
Sigma 0.1% 0.1%
NULL ADJUSTMENT
The nominal 2.5 V null is for a symmetrical swing range at
RATEOUT (1B, 2A). However, a nonsymmetric output swing
may be suitable in some applications. Null adjustment is possible
by injecting a suitable current to SUMJ (1C, 2C). Note that supply
disturbances may reflect some null instability. Digital supply noise
should be avoided, particularly in this case.
SELF-TEST FUNCTION
The ADXRS612 includes a self-test feature that actuates each of
the sensing structures and associated electronics in the same
manner, as if subjected to angular rate. It is activated by standard
Logic High levels applied to Input ST1 (5F, 5G), Input ST2
(4F, 4G), or both. ST1 causes the voltage at RATEOUT to change
about −0.5 V, and ST2 causes an opposite change of +0.5 V. The
self-test response follows the viscosity temperature dependence
of the package atmosphere, approximately 0.25%/°C.
Activating both ST1 and ST2 simultaneously is not damaging.
ST1 and ST2 are fairly closely matched (±5%), but actuating
both simultaneously may result in a small apparent null bias
shift proportional to the degree of self-test mismatch.
ST1 and ST2 are activated by applying a voltage equal to VRATIO
to the ST1 pin and the ST2 pin. The voltage applied to ST1 and
ST2 must never be greater than AVCC.
CONTINUOUS SELF-TEST
The on-chip integration of the ADXRS612 gives it higher reliability
than is obtainable with any other high volume manufacturing
method. Also, it is manufactured under a mature BIMOS process
that has field-proven reliability. As an additional failure detection
measure, power-on self-test can be performed. However, some
applications may warrant continuous self-test while sensing rate.
Details outlining continuous self-test techniques are also
available in a separate application note.
ADXRS612
Rev. 0 | Page 11 of 12
OUTLINE DIMENSIONS
A
B
C
D
E
F
G
BOT
TOM
VIEW
76543
TOP VIEW
3.80 MAX
0.80 BSC
(BALL PITCH)
DETAIL A
BALL DIAMETER
0.60
0.55
0.50
0.60
0.25
7.05
6.85 SQ
6.70
COPLANARITY
0.15
21
*A1 CORNER
INDEX AREA
DETAIL A
A1 BALL PAD
INDICATOR
SEATING
PLANE
4.80
BSC SQ
3.30 MAX
2.50 MIN
*BALL A1 IDENTIFIER IS GOLD PLATED AND CONNECTED
TO THE D/A PAD INTERNALLY VIA HOLES.
060506-A
Figure 24. 32-Lead Ceramic Ball Grid Array [CBGA]
(BG-32-3)
Dimensions shown in millimeters
ORDERING GUIDE
Model Temperature Range Package Description Package Option
ADXRS612BBGZ1–40°C to +105°C 32-Lead Ceramic Ball Grid Array [CBGA] BG-32-3
ADXRS612BBGZ-RL1–40°C to +105°C 32-Lead Ceramic Ball Grid Array [CBGA] BG-32-3
1 Z = RoHS Compliant Part.
ADXRS612
Rev. 0 | Page 12 of 12
NOTES
©2007 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D06521-0-3/07(0)
