Analog Devices ADXSR 614 Service Manual

V

±50°/s 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

Navigation systems
Inertial measurement units
Platform stabilization
Robotics

ADXRS614

GENERAL DESCRIPTION

T

he ADXRS614 is a complete angular rate sensor (gyroscope)
that uses the Analog Devices, Inc. surface-micromachining
process to create a functionally complete and low cost angular
rate sensor integrated with all 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 between SUMJ and
RATEOUT can be used to lower the scale factor. An external
capacitor sets 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 ADXRS614 is available in a 7 mm ×
7 mm × 3 mm BGA chip scale package.

FUNCTIONAL BLOCK DIAGRAM

+5

(ADC REF)

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 SUM J RATEOUT

25kΩ

@ 25°C

100nF

AC

AMP

RATIO

25kΩ

C

OUT

Figure 1. ADXRS614 Block Diagram

VGA

200kΩ ±5%

100nF

ADXRS614

DEMOD

06748-001

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.

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.

ADXRS614

TABLE OF CONTENTS

Features .............................................................................................. 1

Theory of Operation .........................................................................9

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

4/07—Revision 0: Initial Version

Setting Bandwidth.........................................................................9

Temperature Output and Calibration.........................................9

Calibrated Performance................................................................9

ADXRS614 and Supply Ratiometricity ......................................9

Null Adjustment ......................................................................... 10

Self-Test Function ...................................................................... 10

Continuous Self-Test.................................................................. 10

Outline Dimensions ....................................................................... 11

Ordering Guide .......................................................................... 11

Rev. 0 | Page 2 of 12

ADXRS614

SPECIFICATIONS

All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed.

@T

= −40°C to +105°C, VS = AV

A

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

I

OUT

Table 1.

Parameter Conditions

SENSITIVITY (Ratiometric)

Measurement Range

1

2

Initial and Over Temperature
Temperature Drift

3

Nonlinearity Best fit straight line 0.1 % of FS

NULL (Ratiometric)

1

Null −40°C to +105°C 2.5 V
Linear Acceleration Effect Any axis 0.1 °/sec/g

NOISE PERFORMANCE

Rate Noise Density

FREQUENCY RESPONSE

Bandwidth

4

Sensor Resonant Frequency 14.5 kHz

SELF-TEST (Ratiometric)1

ST1 RATEOUT Response
ST2 RATEOUT Response ST2 pin from Logic 0 to Logic 1 1.9 V
Logic 1 Input Voltage 0.8 × V
Logic 0 Input Voltage 0.2 × V
Input Impedance To common 50 kΩ

TEMPERATURE SENSOR (Ratiometric)

V

at 25°C Load = 100 MΩ 2.35 2.5 2.65 V

OUT

Scale Factor
Load to V

5

S

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

V

Input 3 V

RATIO

Supply Current 3.5 5.0 mA
TEMPERATURE RANGE

Specified Performance

1

Parameter is linearly ratiometric with V

2

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 from +25°C to +105°C.

4

Adjusted by external capacitor, COUT.

5

For a change in temperature from 25°C to 26°C. V

= V

CC

= 5 V, V

DD

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

RATIO

= 0.01 µF),

OUT

ADXRS614BBGZ

Min Typ Max

Unit

Clockwise rotation is positive output
Full-scale range over specifications range ±50 ±75 °/sec

22.5 25 27.5 mV/°/sec
±3 %

T

= 25°C

A

0.04

°/sec/√Hz

1 1000 Hz

ST1 pin from Logic 0 to Logic 1 −1.9 V

V

RATIO

V

RATIO

1

@25°C, V

= 5 V 9

RATIO

25
25

mV/°C

S

kΩ
kΩ

V

–40 +105 °C

.

RATIO

is ratiometric to V

TEMP

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

RATIO

Rev. 0 | Page 3 of 12

ADXRS614

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

Acceleration (Any Axis, 0.5 ms)

Unpowered, 2000 g
Powered 2000 g

V

AV

DD,

CC

V

RATIO

Output Short-Circuit Duration

–0.3 V to +6.0 V
AV

CC

Indefinite

(Any Pin to Common)
Operating Temperature Range –55°C to +125°C
Storage Temperature –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. Exercise care during handling to avoid damage.

RATE SENSITIVE AXIS

The ADXRS614 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

LONGITUDI NAL

AXIS

ABCD G

A1

EF

LATERAL AXIS

Figure 2. RATEOUT Signal Increases with Clockwise Rotation

ESD CAUTION

RATE OUT

VCC = 5V

+

7

1

GND

V

RATIO

/2

4.75V

RATE IN

0.25V

06748-002

Rev. 0 | Page 4 of 12

ADXRS614

A

V

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

CP3CP5

NC SUMJ

CP4

CP1

CP2

AV

CC

RATEOUT

7

6

5

4

3

2

1

06748-003

V

DD

RATIO

PGND

`

ST1

ST2

TEMP

GND

GF E D C BA

Figure 3. Pin Configuration

Table 4. Pin Function Descriptions

Pin No. Mnemonic Description

6D, 7D CP5

HV Filter Capacitor (0.1 nF).
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 AV

CC

Positive Analog Supply.
1B, 2A RATEOUT Rate Signal Output.
1C, 2C SUMJ Output Amp Summing Junction.
1D, 2D NC No Connect.
1E, 2E V

RATIO

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 V

DD

Positive Charge Pump Supply.

Rev. 0 | Page 5 of 12

ADXRS614

TYPICAL PERFORMANCE CHARACTERISTICS

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

18

16

14

12

10

8

6

% OF POPULATION

4

2

0

1.4

1.5

1.6

1.7

1.8

1.9

2.0

Figure 4. Null Output at 25°C (V

30

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

3.1

3.2

VOLTS

RATIO

3.3

= 5 V)

06748-004

3.4

3.5

3.6

35

30

25

20

15

% OF POPULATION

10

5

0

–10–9 –8 –7 –6 –5 –4 –3 –2 –1 0 3 6 8 9512 4 7 10

DRIFT (%)

Figure 7. Sensitivity Drift over Temperature

40

06748-007

25

20

15

10

% OF POPULATION

5

0

–0.6 0.6–0.5 0.1–0.4 –0.3 0–0.2 0.50.40.30.2–0.1

Figure 5. Null Drift over Temperature (V

50

45

40

35

30

25

20

% OF POPULATION

15

10

5

0

22

22.5 23 23.5 24 24.5 25 25.5 26 26. 5 27 27. 5 28

Figure 6. Sensitivity at 25°C (V

º/s/ºC

mV/º/s

RATIO

RATIO

= 5 V)

= 5 V)

35

30

25

20

15

% OF POPULATION

10

5

06748-005

06748-006

0

–2.5 –2.4 –2.3 –2.2 –2.1 –2 –1.9 –1.8 –1.7 –1.6 –1. 5 –1.4

VOLTS

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

40

35

30

25

20

15

% OF POPULATION

10

5

0

VOLTS

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

RATIO

RATIO

= 5 V)

= 5 V)

–1.3

2.51.3 1.4 1.5 1.6 1. 7 1.8 1.9 2 2.1 2.2 2.3 2.4

06748-008

06748-009

Rev. 0 | Page 6 of 12

ADXRS614

14

12

10

8

6

% OF POPULATION

4

2

0

50 54 58 62 66 70 74 78 82 86 90 94 98

º/s

Figure 10 .Measurement Range

2.5

2

1.5

1

0.5

0

VOLTS

–0.5

–1

–1.5

–2

–2.5

–40 120

–20 0 20 40 60 80 100

TEMPERATURE (ºC)

Figure 11. Typical Self-Test Change over Temperature

30

25

20

06748-010

06748-011

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

VOLTS

Figure 13. 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

Figure 14. V

60

50

40

30

Output at 25°C (V

TEMP

TEMPERATURE ( °C)

Output over Temperature (V

TEMP

RATIO

= 5 V)

256 PARTS

RATIO

= 5 V)

REF

Y

X

+45°

–45°

06748-013

06748-014

15

10

% OF POPULATION

5

0

2.5

2.6

2.7

2.8

2.9

3.0

3.1

3.2

3.3

3.4

(mA)

Figure 12. Current Consumption at 25°C (V

20

g OR °/s

10

0

–10

06748-012

3.5

3.6

3.7

3.8

3.9

4.0

4.1

4.2

4.3

4.4

4.5

= 5 V)

RATIO

–20

750 770 810 830 850790

TIME (ms)

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

06748-015

Rev. 0 | Page 7 of 12

ADXRS614

1.6

1.4

0.10

1.2

1.0

0.8

(°/s)

0.6

0.4

0.2

0

100 10k

1k

(Hz)

Figure 16. Typical Response to 10 g Sinusoidal Vibration

(Sensor Bandwidth = 2 kHz)

400

300

DUT1 OFFS ET BY +200°/ s

DUT2 OFFS ET BY –200°/ s

(°/s)

200

100

0

–100

–200

–300

LAT

LONG

RATE

0.05

0

(°/s)

–0.05

–0.10

0112010080604020

06748-016

TIME (Hours)

40

06748-019

Figure 19. Typical Shift in 90 sec Null Averages Accumulated

over 140 Hours

0.10

0.05

0

(°/s)

–0.05

–400

0 250150100 20050

(ms)

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

(Sensor Bandwidth = 40 Hz)

1

0.1

(°/s rms)

0.01

0.001

0.01 0.1 100k10k1k100101

AVERAGE TIME (Seconds)

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

–0.10

0 360018001200 30002400600

06748-017

TIME (S econds)

06748-020

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

0.1

0.01

(°/s/ Hz rms)

0.001

0.0001
10 100k1k100

06748-018

(Hz)

10k

06748-021

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

Rev. 0 | Page 8 of 12

ADXRS614

(

)

V

THEORY OF OPERATION

The ADXRS614 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 through CP4 can
be omitted and this supply can be connected to CP5 (Pin 6D,
Pin 7D). Note that CP5 should not be grounded when power is
applied to the ADXRS614. Although no damage occurs, under
certain conditions the charge pump may fail to start up after the
ground is removed without first removing power from the
ADXRS614.

SETTING BANDWIDTH

External Capacitor C
chip R

resistor to create a low-pass filter to limit the

OUT

bandwidth of the ADXRS614 rate response. The –3 dB
frequency set by R

OUT

()

and can be well controlled because R
during manufacturing to be 200 kΩ ±1%. Any external resistor
applied between the RATEOUT pin (1B, 2A) and SUMJ pin
(1C, 2C) results in:

=

R

OUT

()

In general, an additional hardware or software filter is added to
attenuate high frequency noise arising from demodulation
spikes at the gyro’s 14 kHz resonant frequency (the noise spikes
at 14 kHz can be clearly seen in the power spectral density
curve shown in

Figure 21). Typically, this additional filter’s
corner frequency is set to greater than 5× the required
bandwidth to preserve good phase response.

Figure 22 shows the effect of adding a 250 Hz filter to the
output of an ADXRS614 set to 40 Hz bandwidth (as shown in
Figure 21). High frequency demodulation artifacts are
attenuated by approximately 18 dB.

is used in combination with the on-

OUT

OUT

k200

k200

and C

1

×

+

is:

OUT

CRf×××=π2

OUTOUT

has been trimmed

OUT

R

EXT

R

EXT

0.1

0.01

0.001

0.0001

(°/s/ Hz rms)

0.00001

0.000001
10 100k1k100

(Hz)

Figure 22. Noise Spectral Density with Additional 250 Hz Filter

10k

TEMPERATURE OUTPUT AND CALIBRATION

It is common practice to temperature-calibrate gyros to
improve their overall accuracy. The ADXRS614 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 temperature
coefficient. Therefore, buffering the output is recommended.

The voltage at the TEMP pin (3F, 3G) is nominally 2.5 V at
25°C and V

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

RATIO

at 25°C. Although the TEMP output is highly repeatable, it has
only modest absolute accuracy.

V

RATIO

R

FIXED

Figure 23. ADXRS614 Temperature Sensor Structure

R

TEMP

TEMP

6748-023

CALIBRATED PERFORMANCE

Using a 3-point calibration technique, it is possible to calibrate
the null and sensitivity drift of the ADXRS614 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.

ADXRS614 AND SUPPLY RATIOMETRICITY

The ADXRS614 RATEOUT and TEMP signals are ratiometric
to the V
temperature outputs are proportional to V
ADXRS614 is most easily used with a supply-ratiometric ADC
that results in self-cancellation of errors due to minor supply
variations. There is some small error due to nonratiometric

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

RATIO

. Thus, the

RATIO

6748-022

Rev. 0 | Page 9 of 12

ADXRS614

behavior. Typical ratiometricity error for null, sensitivity, self­test, and temperature output is outlined in

Note that V

must never be greater than AV

RATIO

Table 3. Ratiometricity Error for Various Parameters

Parameter VS = V

= 4.75 V VS = V

RATIO

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%

NULL ADJUSTMENT

The nominal 2.5 V null is for a symmetrical swing range at
RATEOUT (1B, 2A). However, a nonsymmetrical 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.

Tabl e 3.

CC.

RATIO

= 5.25 V

SELF-TEST FUNCTION

The ADXRS614 includes a self-test feature that actuates each of
the sensing structures and associated electronics 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 −1.9 V, and
ST2 causes an opposite change of +1.9 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 of greater than

0.8 × V
deactivated by applying a voltage of less than 0.2 × V

to the ST1 and ST2 pins. ST1 and ST2 are

RATIO

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 one-chip integration of the ADXRS614 gives it higher
reliability than is obtainable with any other high volume
manufacturing method. In addition, it is manufactured under a
mature BiMOS process with field-proven reliability. As an
additional failure detection measure, a 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

ADXRS614

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

T

M

O

B

T

O

W

V

IE

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

ADXRS614BBGZ
ADXRS614BBGZ-RL
EVAL-ADXRS614Z

1

Z = RoHS Compliant Part.

1

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
Evaluation Board

Rev. 0 | Page 11 of 12

ADXRS614

NOTES

©2007 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D06748-0-4/07(0)

Rev. 0 | Page 12 of 12