ANALOG DEVICES ADXRS646 Service Manual

Vibration Rejecting Yaw Rate Gyroscope

ADXRS646

Rev. 0

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V

DD

AGND

PGND

AV

CC

ST2 ST1 TEMP V

RATIO

R

OUT

CP1 CP2 CP3 CP4 CP5 SUMJ RATEOUT

DEMOD

180kΩ ±1%

22nF

100nF

22nF

100nF

100nF

100nF

DRIVE

AMP

MECHANICAL

SENSOR

CHARGE PUMP
AND VOLTAG E

REGULATOR

C

OUT

6V

6V

3V TO 6V

(ADC REF)

AC

AMP

VGA

25kΩ

@ 25°C

ADXRS646

25kΩ

SELF-TEST

09771-001

Data Sheet

FEATURES

12°/hr bias stability
Z-axis (yaw rate) response

0.01°/√sec angle random walk
High vibration rejection over wide frequency
Measurement range extendable to a maximum of ±450°/sec
10,000 g powered shock survivability
Ratiometric to referenced supply
6 V single-supply operation

−40°C to +105°C operation
Self-test on digital command
Ultrasmall and light (<0.15 cc, <0.5 gram)
Temperature sensor output
Complete rate gyroscope on a single chip
RoHS compliant

APPLICATIONS

Industrial applications
Severe mechanical environments
Platform stabilization

High Stability, Low Noise

GENERAL DESCRIPTION

The ADXRS646 is a high performance angular rate sensor
(gyroscope) that offers excellent vibration immunity. Bias
stability is a widely-recognized figure of merit for high
performance gyroscopes, but in real-world applications,
vibration sensitivity is often a more significant performance
limitation and should be considered in gyroscope selection. The

ADXRS646 offers superior vibration immunity and acceleration

rejection as well as a low bias drift of 12°/hr (typical), enabling it
to offer rate sensing in harsh environments where shock and
vibration are present.

The ADXRS646 is manufactured using the Analog Devices,
Inc., patented high volume BiMOS surface-micromachining
process. An advanced, differential, quad sensor design provides
the improved acceleration and vibration rejection. The output
signal, RATEOUT, is a voltage proportional to angular rate
about the axis normal to the top surface of the package. The
measurement range is a minimum of ±250°/sec. The output is
ratiometric with respect to a provided reference supply. 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 ADXRS646 is available in a 7 mm × 7 mm × 3 mm CBGA
chip-scale package.

FUNCTIONAL BLOCK DIAGRAM

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.

Figure 1.

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Tel: [phone] www.analog.com

ADXRS646 Data Sheet

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

9/11—Revision 0: Initial Version

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

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

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

Supply Ratiometricity ................................................................ 10

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

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

Continuous Self-Tes t .................................................................. 10

Modifying the Measurement Range ........................................ 10

Immunity to Vibration .............................................................. 11

Outline Dimensions ....................................................................... 12

Ordering Guide .......................................................................... 12

Rev. 0 | Page 2 of 12

Data Sheet ADXRS646

Bandwidth

±3 dB user adjustable up to specification

1000

Hz

Input Impedance

ST1 pin or ST2 pin to common

40

50

100

kΩ

Scale Factor4

25°C, V

= 6 V

10 mV/°C

Specified Performance

−40 +105

°C

SPECIFICATIONS

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

= 25°C, VS = AVCC = VDD = 6 V, V

T

A

otherwise noted.

Table 1.

Parameter Test Conditions/Comments Min Typ Max Unit

SENSITIVITY1 Clockwise rotation is positive output

Measurement Range2 Full-scale range over specifications range ±250 ±300 °/sec
Initial
Temperature Drift3 ±3 %
Nonlinearity Best fit straight line 0.01 % of FS

NULL1

Null −40°C to +105°C 2.7 3.0 3.3 V
Calibrated Null4 −40°C to +105°C ±0.1 °/sec
Temperature Drift3 ±3 °/sec
Linear Acceleration Effect Any axis 0.015 °/sec/g
Vibration Rectification 25 g rms, 50 Hz to 5 kHz 0.0001 °/sec/g2

NOISE PERFORMANCE

Rate Noise Density TA ≤ 25°C 0.01 °/sec/√Hz
Rate Noise Density TA ≤ 105°C 0.015 °/sec/√Hz
Resolution Floor

FREQUENCY RESPONSE

5

Sensor Resonant Frequency 15.5 17.5 20 kHz

SELF-TEST1

ST1 RATEOUT Response
ST2 RATEOUT Response ST2 pin from Logic 0 to Logic 1 50 °/sec
ST1 to ST2 Mismatch6 −5
Logic 1 Input Voltage ST1 pin or ST2 pin 4 V
Logic 0 Input Voltage 2 V

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

RAT IO

= 0.01 µF), I

OUT

= 100 µA, ±1 g, unless

OUT

8.5 9 9.5 mV/°/sec

TA = 25°C, 1 minute to 1 hour in-run

12 °/hr

ST1 pin from Logic 0 to Logic 1 −50 °/sec

±0.5 +5

%

TEMPERATURE SENSOR1

V

at 25°C Load = 10 MΩ 2.8 2.9 3.0 V

OUT

RAT IO

Load to V

S

25 kΩ

Load to Common 25 kΩ
TURN-ON TIME4 Power on to ±0.5°/sec of final with CP5 = 100 nF 50 ms
OUTPUT DRIVE CAPABILITY

Current Drive For rated specifications 200 µA

Capacitive Load Drive 1000 pF
POWER SUPPLY

Operating Voltage (VS) 5.75 6.00 6.25 V

Quiescent Supply Current 4 mA
TEMPERATURE RANGE

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

Based on characterization.

5

Adjusted by external capacitor, C

6

Self-test mismatch is described as (ST2 + ST1)/((ST2 − ST1)/2).

.

RATIO

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

OUT

Rev. 0 | Page 3 of 12

ADXRS646 Data Sheet

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

Acceleration (Any Axis, 0.5 ms)

Unpowered 10,000 g
Powered 10,000 g

VDD, AV

CC

V

AVCC

RATIO

−0.3 V to +6.6 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
10,000 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

LONGITUDINAL

AXIS

ABCD G

A1

EF

LATERAL AXIS

Figure 2. RATEOUT Signal Increases with Clockwise Rotation

AVCC = 5V

+

7

1

GND

V

RATIO

RATE OUT

4.75V

/2

RATE IN

0.25V

ESD CAUTION

09771-002

Rev. 0 | Page 4 of 12