Analog Devices ADXSR 612 Service Manual

V

±250°/sec Yaw Rate Gyro

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 propor­tional 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 condi­tioning circuits. The ADXRS612 is available in a 7 mm × 7 mm ×
3 mm BGA chip-scale package.

FUNCTIONAL BLOCK DIAGRAM

+5

(ADC REF)

ADXRS612

100nF

100nF

100nF

+5V

+5V

AV

CC

AGND

V

DD

PGND

ST2 ST1 TEMP V

SELF-TEST

AMP

22nF

MECHANICAL

SENSOR

CHARGE PUMP
AND VOLTAGE

REGULATOR

22nF

DRIVE

CP1 CP2 CP3 CP4 CP5 SUMJ RATEOUT

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
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.

25kΩ

@ 25°C

AC

AMP

100nF

RATIO

25kΩ

C

OUT

VGA

180kΩ ±1%

ADXRS612

DEMOD

06521-001

Figure 1.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©2007 Analog Devices, Inc. All rights reserved.

ADXRS612

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

REVISION HISTORY

3/07—Revision 0: Initial Version

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

Rev. 0 | Page 2 of 12

ADXRS612

SPECIFICATIONS

All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed. TA = −40°C to +105°C, VS = AVCC =

= 5 V, V

V

DD

Table 1.

Parameter Conditions

SENSITIVITY

Measurement Range
Initial and Over Temperature
Temperature Drift
Nonlinearity Best fit straight line 0.1 % of FS

1

NULL

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

FREQUENCY RESPONSE

Bandwidth
Sensor Resonant Frequency 12 14.5 17 kHz

SELF-TEST

ST1 RATEOUT Response
ST2 RATEOUT Response ST2 pin from Logic 0 to Logic 1 300 525 750 mV
ST1 to ST2 Mismatch
Logic 1 Input Voltage 3.3 V
Logic 0 Input Voltage 1.7 V
Input Impedance To common 40 50 100 kΩ

TEMPERATURE SENSOR

V

at 25°C Load = 10 MΩ 2.35 2.5 2.65 V

OUT

Scale Factor

Load to V

Load to Common
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 V

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, C

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. V

= AVCC, angular rate = 0°/sec, bandwidth = 80 Hz (C

RATIO

1

2

3

Clockwise rotation is positive output
Full-scale range over specifications range ±250 ±300 °/sec

−40°C to +105°C
±2 %

T

≤ 25°C

A

4

1

5

1

6

S

RATIO

. Reducing bandwidth below 0.01 Hz does not result in further noise improvement.

OUT

0.01 2500 Hz

ST1 pin from Logic 0 to Logic 1 −750 −525 −300 mV

−5

@ 25°C, V

RATIO

.

is ratiometric to V

TEMP

= 0.01 µF), I

OUT

= 100 µA, ±1 g, unless otherwise noted.

OUT

ADXRS612BBGZ

Min Typ Max

6.2 7.0 7.8 mV/°/sec

0.06

+5

= 5 V 9

. See the Temperature Output and Calibration section for more information.

RATIO

25

25

Unit

°/sec/√Hz

%

mV/°C

kΩ

kΩ

Rev. 0 | Page 3 of 12

ADXRS612

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

Acceleration (Any Axis, 0.5 ms)

Unpowered 2000 g
Powered 2000 g

VDD, AV

CC

V

AVCC

RATIO

–0.3 V to +6.0 V

ST1, ST2 AVCC
Output Short-Circuit Duration

Indefinite

(Any Pin to Common)
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 rate­sensing 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

LONGITUDI NAL

AXIS

ABCD G

A1

LATERAL AXIS

Figure 2. RATEOUT Signal Increases with Clockwise Rotation

EF

+

1

7

VCC = 5V

GND

V

RATIO

RATE OUT

4.75V

/2

RATE IN

0.25V

ESD CAUTION

06521-002

Rev. 0 | Page 4 of 12

ADXRS612

A

V

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

CP3CP5

NC SUMJ

CP4

CP1

CP2

AV

CC

RATEOUT

7

6

5

4

3

2

1

06521-023

V

DD

RATIO

PGND

ST1

ST2

TEMP

GND

GF E D C BA

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 V

Reference Supply for Ratiometric Output.

RATIO

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.

Rev. 0 | Page 5 of 12

ADXRS612

TYPICAL PERFORMANCE CHARACTERISTICS

N > 1000 for all typical performance plots, unless otherwise noted.

16

14

12

25

20

10

8

6

% OF POPULATION

4

2

0

2.20

2.25

2.30

2.35

2.40

Figure 4. Null Output at 25°C (V

25

20

15

10

% OF POPULATION

5

0

–0.30

–0.25

–0.20

–0.15

–0.100–0.05

Figure 5. Null Drift over Temperature (V

2.50

2.45

VOLTS

(°/sec/°C)

15

10

% OF POPULATION

5

0

2.55

2.60

2.65

2.70

2.75

2.80

6521-003

= 5 V)

RATIO

0.05

0.10

0.15

0.20

0.25

0.30

06521-004

RATIO

= 5 V)

–7 –5 –4–6 –3 –2 –1 0 1 2 3 4 5 6 7

% DRIFT

Figure 7. Sensitivity Drift over Temperature

45

40

35

30

25

20

15

% OF POPULATION

10

5

0

–675 –625 –575 –525 –425–475 –375

(mV)

Figure 8. ST1 Output Change at 25°C (V

RATIO

= 5 V)

06521-006

06521-007

30

25

20

15

10

% OF POPULATION

5

0

6.36.46.56.66.76.86.97.07.17.27.37.47.57.67.7

Figure 6. Sensitivity at 25°C (V

(mV/°/ sec)

RATIO

= 5 V)

06521-005

Rev. 0 | Page 6 of 12

45

40

35

30

25

20

15

% OF POPULATION

10

5

0

375 425 450400 475 500 525 550 600 625575 650 675

(mV)

Figure 9. ST2 Output Change at 25°C (V

RATIO

= 5 V)

06521-008

ADXRS612

c

50

45

40

35

30

25

20

% OF POPULATION

15

10

5

0

–5 –4 –3 –2 –1 1 2 3 4 50

% MISMAT CH

Figure 10. Self-Test Mismatch at 25°C (V

RATIO

= 5 V)

06521-009

40

35

30

25

20

15

% OF POPULATION

10

5

0

2.40 2.42 2.44 2.46 2.48 2.50 2.54 2.56 2. 58 2.602.52

Figure 13. V

Output at 25°C (V

TEMP

VOLTS

RATIO

= 5 V)

06521-012

800

600

400

200

0

(mV)

–200

–400

–600

–800

–40 –20 0 20 40 80 100 12060

ST2

ST1

TEMPERATURE (°C)

Figure 11. Typical Self-Test Change over Temperature

40

35

30

25

20

15

% OF POPULATION

10

5

0

3.0 3.1 3.2 3.3 3. 4 3.5 3.7 3.8 3.9 4.0 4.13.6

(mA)

Figure 12. Current Consumption at 25°C (V

RATIO

= 5 V)

3.3

3.1

2.9

2.7

2.5

2.3

VOLTS

2.1

1.9

1.7

1.5
–40 –20 0 20 40 60 100 12080

06521-010

Figure 14. V

60

50

40

30

20

g OR °/se

10

0

–10

–20

750 770 810 830 850790

06521-011

Output over Temperature, 256 Parts (V

TEMP

TEMPERATURE ( °C)

TIME (ms)

256 PARTS

RATIO

REF

Y

X

+45°

–45°

= 5 V)

06521-013

06521-014

Figure 15. g and g × g Sensitivity for a 50 g, 10 ms Pulse

Rev. 0 | Page 7 of 12

ADXRS612

1.6

1.4

0.10

1.2

1.0

0.8

(°/sec)

0.6

0.4

0.2

0

100 10k

1k

(Hz)

Figure 16. Typical Response to 10 g Sinusoidal Vibration

LAT

LONG

RATE

06521-015

0.05

0

(°/sec)

–0.05

–0.10

0 14012010080604020

Figure 19. Typical Shift in 90 sec Null Averages Accumulated over 140 Hours

(Sensor Bandwidth = 2 kHz)

400

300

200

100

0

(°/sec)

–100

–200

–300

–400

02

DUT1 OFFSET BY +200°/sec

DUT2 OFFSET BY –200°/sec

(ms)

50150100 20050

06521-016

Figure 17. Typical High g (2500 g) Shock Response

0.10

0.05

0

(°/sec)

–0.05

–0.10

0 360018001200 30002400600

Figure 20. Typical Shift in Short Term Null (Bandwidth = 1 Hz)

(Sensor Bandwidth = 40 Hz)

1

0.1

TIME (Hours)

TIME (Seconds)

06521-018

06521-019

0.1

(°/sec rms)

0.01

0.001

0.01 0.1 100k10k1k100101

AVERAGING TIME (Seconds)

Figure 18. Typical Root Allan Deviation at 25°C vs. Averaging Time

06521-017

Rev. 0 | Page 8 of 12

0.01

(°/sec/ Hz rms)

0.001

0.0001
10 100k1k100

(Hz)

10k

Figure 21. Typical Noise Spectral Density (Bandwidth = 40 Hz)

06521-020

ADXRS612

(

)

()(

)

V

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 neces­sary 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 C
chip R

resistor to create a low-pass filter to limit the bandwidth

OUT

of the ADXRS612 rate response. The −3 dB frequency set by
R

OUT

and C

OUT

is

and can be well controlled because R
during manufacturing to be 180 kΩ ± 1%. Any external resistor
applied between the RATEOUT pin (1B, 2A) and SUMJ pin
(1C, 2C) results in

In general, an additional filter (in either hardware or software)
is added to attenuate high frequency noise arising from demodu­lation 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
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

Figure 21). High frequency demodulation artifacts are

in
attenuated by approximately 18 dB.

is used in combination with the on-

OUT

CRf ×××= π2/1

OUTOUTOUT

has been trimmed

OUT

RRR +×= k180/k180

EXTEXTOUT

Figure 21. Normally, this additional

0.1

0.01

0.001

0.0001

(°/sec/ Hz rms)

0.00001

0.000001
10 100k1k100

(Hz)

Figure 22. Noise Spectral Density with Additional 250 Hz Filter

10k

6521-021

TEMPERATURE OUTPUT AND CALIBRATION

It is common practice to temperature-calibrate gyros to improve
their overall accuracy. The ADXRS612 has a temperature propor­tional 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

= 5 V. The temperature coefficient is ~9 mV/°C at 25°C.

V

RATIO

Although the TEMP output is highly repeatable, it has only
modest absolute accuracy.

RATIO

R

FIXEDRTEMP

Figure 23. ADXRS612 Temperature Sensor Structure

V

TEMP

6521-022

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.

Rev. 0 | Page 9 of 12

ADXRS612

ADXRS612 AND SUPPLY RATIOMETRICITY

The ADXRS612 RATEOUT and TEMP signals are ratiometric
to the V
temperature outputs are proportional to V

voltage; that is, the null voltage, rate sensitivity, and

RATIO

. So the ADXRS612

RATIO

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

Note that V

must never be greater than AVCC.

RATIO

Tabl e 4.

Table 4. Ratiometricity Error for Various Parameters

Parameter VS = 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%

V

TEMP

Mean −0.3% −0.5%
Sigma 0.1% 0.1%

= 4.75 V VS = V

RATIO

RATIO

= 5.25 V

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 V

RATIO

to the ST1 pin and the ST2 pin. The voltage applied to ST1 and
ST2 must never be greater than AV

.

CC

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.

Rev. 0 | Page 10 of 12

ADXRS612

OUTLINE DIMENSIONS

7.05

6.85 SQ

6.70

76543

*

A1 CORNER

INDEX AREA

21

A

B

C

D

E

F

G

3.30 MAX

2.50 MIN

COPLANARIT Y

0.15

060506-A

3.80 MAX

A1 BALL PAD
INDICATOR

4.80

TOP VIEW

DETAIL A

BSC SQ

0.80 BSC

(BALL PITCH)

DETAIL A

0.60

0.25

SEATING

PLANE

*

BALL A1 IDENTIFIER IS GOLD PLATED AND CONNECTED

TO THE D/A PAD INTERNALL Y VIA HOLE S.

0.60

0.55

0.50

BALL DIAMETER

B

T

O

T

M

O
W

V

IE

Figure 24. 32-Lead Ceramic Ball Grid Array [CBGA]

G-32-3)

(B

Dimensions shown in millimeters

ORDERING GUIDE

Model Temperature Range Package Description Package Option

ADXRS612BBGZ
ADXRS612BBGZ-RL

1

Z = RoHS Compliant Part.

1

1

–40°C to +105°C 32-Lead Ceramic Ball Grid Array [CBGA] BG-32-3
–40°C to +105°C 32-Lead Ceramic Ball Grid Array [CBGA] BG-32-3

Rev. 0 | Page 11 of 12

ADXRS612

NOTES

©2007 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D06521-0-3/07(0)

Rev. 0 | Page 12 of 12