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150/Sec Yaw Rate Gyroscope ADXRS623
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 -40C to +105C operation Self-test on digital command Ultrasmall and light (<0.15 cc, <0.5 gram) Temperature sensor output RoHS compliant
GENERAL DESCRIPTION
The ADXRS623 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 the angular rate about the axis that is normal to the top surface of the package. The output is ratiometric with respect to a provided reference supply. 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 ADXRS623 is available in a 7 mm x 7 mm x 3 mm ceramic ball grid array (CBGA) package.
APPLICATIONS
Inertial measurement units Platform stabilization Robotics
FUNCTIONAL BLOCK DIAGRAM
+5V (ADC REF) 100nF +5V AVCC 100nF AGND DEMOD
DRIVE AMP
ST2
ST1
TEMP
VRATIO
ADXRS623
SELF-TEST
25k @ 25C
25k
MECHANICAL SENSOR
AC AMP
VGA
+5V
VDD CHARGE PUMP AND VOLTAGE REGULATOR PGND CP1 CP2 CP3 CP4 CP5 SUMJ 100nF 22nF 22nF COUT
180k 1%
100nF
RATEOUT
08890-001
Figure 1.
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 (c)2010 Analog Devices, Inc. All rights reserved.
ADXRS623 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 ADXRS623 and Supply Ratiometricity ................................... 10 Null Adjustment ......................................................................... 10 Self-Test Function ...................................................................... 10 Continuous Self-Test.................................................................. 10 Outline Dimensions ....................................................................... 11 Ordering Guide .......................................................................... 11
REVISION HISTORY
3/10--Revision 0: Initial Version
Rev. 0 | Page 2 of 12
ADXRS623 SPECIFICATIONS
All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed. TA = -40C to +105C, VS = AVCC = VDD = 5 V, VRATIO = AVCC, angular rate = 0/sec, bandwidth = 80 Hz (COUT = 0.01 F), IOUT = 100 A, 1 g, unless otherwise noted. Table 1.
Parameter SENSITIVITY (RATIOMETRIC) 1 Measurement Range2 Initial and over Temperature Temperature Drift3 Nonlinearity NULL (RATIOMETRIC)1 Null Null Drift over Temperature Linear Acceleration Effect NOISE PERFORMANCE Rate Noise Density FREQUENCY RESPONSE Bandwidth4 Sensor Resonant Frequency SELF-TEST (RATIOMETRIC)1 ST1 RATEOUT Response ST2 RATEOUT Response Logic 1 Input Voltage Logic 0 Input Voltage Input Impedance TEMPERATURE SENSOR (RATIOMETRIC)1 VOUT at 25C Scale Factor5 Load to VS Load to Common TURN-ON TIME OUTPUT DRIVE CAPABILITY Current Drive Capacitive Load Drive POWER SUPPLY Operating Voltage (VS) VRATIO Input Supply Current TEMPERATURE RANGE Specified Performance
1 2
Test Conditions/Comments Clockwise rotation is positive output Full-scale range over specifications range
Min 150 11.25
Typ
Max
Unit /sec mV//sec % % of FS V mV /sec/g /sec/Hz
Best fit straight line -40C to +105C -40C to +105C Any axis TA = 25C 1
12.5 3 0.1 2.5
13.75
250 0.1 0.04 3000 14.5
Hz kHz mV mV V V k V mV/C k k ms A pF V V mA C
ST1 pin from Logic 0 to Logic 1 ST2 pin from Logic 0 to Logic 1
-500 500 0.8 x VRATIO
-1000 1000 0.2 x VRATIO
To common Load = 100 M At 25C, VRATIO = 5 V 2.35
50 2.5 9.1 25 25 2.65
Power on to 1/2/sec of final For rated specifications
50 200 1000 4.75 3 5.00 3.5 -40 5.25 VS 5.0 +105
Parameter is linearly ratiometric with VRATIO. The maximum range possible, including output swing range, initial offset, sensitivity, offset drift, and sensitivity drift at 5 V supplies. 3 From +25C to -40C or from +25C to +105C. 4 Adjusted by external capacitor, COUT. 5 For a change in temperature from 25C to 26C. VTEMP is ratiometric to VRATIO. See the Temperature Output and Calibration section for more details.
Rev. 0 | Page 3 of 12
ADXRS623 ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Acceleration (Any Axis, 0.5 ms) Unpowered Powered VDD, AVCC VRATIO Output Short-Circuit Duration (Any Pin to Common) Operating Temperature Range Storage Temperature Range Rating 2000 g 2000 g -0.3 V to +6.0 V AVCC Indefinite -40C to +125C -65C to +150C
RATE-SENSITIVE AXIS
The ADXRS623 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 VCC = 5V LONGITUDINAL AXIS + VRATIO/2 7 A1 A B C D E F LATERAL AXIS 1 G GND RATE IN 0.25V
08890-002
RATE OUT
4.75V
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 >2000 g and can exceed the absolute maximum rating of the device. Exercise care during handling to avoid damage.
Figure 2. RATEOUT Signal Increases with Clockwise Rotation
ESD CAUTION
Rev. 0 | Page 4 of 12
ADXRS623 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
PGND VDD CP5 CP3 CP4 7 6 ST1 ST2 TEMP CP1 CP2 AVCC 5 4 3 2 1 AGND G F VRATIO E NC D SUMJ C B A RATEOUT
08890-003
NC = NO CONNECT
Figure 3. Pin Configuration
Table 3. Pin Function Descriptions
Pin No. 6D, 7D 6A, 7B 6C, 7C 5A, 5B 4A, 4B 3A, 3B 1B, 2A 1C, 2C 1D, 2D 1E, 2E 1F, 2G 3F, 3G 4F, 4G 5F, 5G 6G, 7F 6E, 7E Mnemonic CP5 CP4 CP3 CP1 CP2 AVCC RATEOUT SUMJ NC VRATIO AGND TEMP ST2 ST1 PGND VDD Description HV Filter Capacitor (100 nF). Charge Pump Capacitor (22 nF). Charge Pump Capacitor (22 nF). Charge Pump Capacitor (22 nF). Charge Pump Capacitor (22 nF). Positive Analog Supply. Rate Signal Output. Output Amplifier Summing Junction. No Connect. Reference Supply for Ratiometric Output. Analog Supply Return. Temperature Voltage Output. Self-Test for Sensor 2. Self-Test for Sensor 1. Charge Pump Supply Return. Positive Charge Pump Supply.
Rev. 0 | Page 5 of 12
ADXRS623 TYPICAL PERFORMANCE CHARACTERISTICS
N > 1000 for all typical performance plots, unless otherwise noted.
25
30
PERCENT OF POPULATION (%)
20
PERCENT OF POPULATION (%)
25
20
15
15
10
10
5
5
08890-004
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
-10
-8
-6
-4
-2
0
2
4
6
8
10
RATEOUT (V)
PERCENT DRIFT (%)
Figure 4. Null Output at 25C (VRATIO = 5 V)
Figure 7. Sensitivity Drift over Temperature
45 40
45 40
PERCENT OF POPULATION (%)
PERCENT OF POPULATION (%)
35 30 25 20 15 10 5
08890-005
35 30 25 20 15 10 5
08890-008 08890-009
-500
-600
-700
-800
-900
-1000
-1100
-1200
-1300
-0.4 -0.3 -0.2 -0.1
0 (/s/C)
0.1
0.2
0.3
0.4
0.5
ST1 (mV)
Figure 5. Null Drift over Temperature (VRATIO = 5 V)
Figure 8. ST1 Output Change at 25C (VRATIO = 5 V)
35 30
45 40
PERCENT OF POPULATION (%)
PERCENT OF POPULATION (%)
35 30 25 20 15 10 5 0
25 20 15 10 5
0
500
600
700
800
900
1000
1100
1200
1300
11.00
11.25
11.50
11.75
12.00
12.25
12.50
12.75
13.00
13.25
13.50
13.75
14.00
08890-006
SENSITIVITY (mV//s)
ST2 (mV)
Figure 6. Sensitivity at 25C (VRATIO = 5 V)
Rev. 0 | Page 6 of 12
Figure 9. ST2 Output Change at 25C (VRATIO = 5 V)
1400
-1400
0 -0.5
0
08890-007
0
0
ADXRS623
30
40 35
PERCENT OF POPULATION (%)
PERCENT OF POPULATION (%)
08890-010
25
30 25 20 15 10 5 0 2.40 2.42 2.44 2.46 2.48 2.50 2.52 2.54 2.56 2.58 2.60 VOLTAGE (V)
20
15
10
5
125
135
145
155
165
175
185
195
MEASUREMENT RANGE (/s)
Figure 10. Measurement Range
Figure 13. VTEMP Output at 25C (VRATIO = 5 V)
3.3 3.1
1.5
1.0 ST2 0.5
2.9 2.7
VOLTAGE (V)
VOLTAGE (V)
2.5 2.3 2.1
0
-0.5 ST1 -1.0
1.9 1.7 256 PARTS
08890-014
-20
08890-011
-1.5 -40
0
20
40
60
80
100
120
1.5 -40
-20
0
20
40
60
80
100
120
TEMPERATURE (C)
TEMPERATURE (C)
Figure 11. Typical Self-Test Change over Temperature
30
Figure 14. VTEMP Output over Temperature (VRATIO = 5 V)
60 50 40 REF Y X +45 -45
PERCENT OF POPULATION (%)
25
20
30
15
(g OR /s)
20 10 0
10
5
-10
0 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 CURRENT CONSUMPTION (mA)
08890-012
770
790 TIME (ms)
810
830
850
Figure 12. Current Consumption at 25C (VRATIO = 5 V)
Figure 15. g and g x g Sensitivity for a 50 g, 10 ms Pulse
Rev. 0 | Page 7 of 12
08890-015
-20 750
08890-013
0
ADXRS623
2.0 1.8 1.6 PEAK RATEOUT (/s) 1.4 1.2
(/s)
08890-016
0.10
LATITUDE LONGITUDE RATE
0.05
1.0 0.8 0.6
0
-0.05
0.4 0.2
0 20 40 60 80 100 120 140
08890-019
0 100
-0.10 TIME (Hours)
1k FREQUENCY (Hz)
10k
Figure 16. Typical Response to 10 g Sinusoidal Vibration (Sensor Bandwidth = 2 kHz)
Figure 19. Typical Shift in 90 Sec Null Averages Accumulated over 140 Hours
400 300 DUT1 OFFSET BY +200/s 200 100
(/s)
0.10
0.05
(/s)
0 -100 -200 -300 -400 0 50 100 (ms) 150 200 250 DUT2 OFFSET BY -200/s
0
-0.05
08890-017
0
600
1200
1800 TIME (Seconds)
2400
3000
3600
Figure 17. Typical High g (2500 g) Shock Response (Sensor Bandwidth = 40 Hz)
1
Figure 20. Typical Shift in Short-Term Null (Bandwidth = 1 Hz)
0.1
0.1
0.01
(/s/ Hz rms)
(/s rms)
0.01
0.001
08890-018
0.1
1
10
100
1k
10k
100k
100
1k FREQUENCY (Hz)
10k
100k
AVERAGE TIME (Seconds)
Figure 18. Typical Root Allan Deviation at 25C vs. Averaging Time
Figure 21. Typical Noise Spectral Density (Bandwidth = 40 Hz)
Rev. 0 | Page 8 of 12
08890-021
0.001 0.01
0.0001 10
08890-020
-0.10
ADXRS623 THEORY OF OPERATION
The ADXRS623 operates on the principle of a resonator gyroscope. 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 while rotating. 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 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 the CP5 pin (6D, 7D). Note that CP5 should not be grounded when power is applied to the ADXRS623. 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 ADXRS623. Figure 22 shows the effect of adding a 250 Hz filter to the output of an ADXRS623 set to 40 Hz bandwidth (as shown in Figure 21). High frequency demodulation artifacts are attenuated by approximately 18 dB.
0.1
0.01
(/s/ Hz rms)
0.001
0.0001
0.00001
100
1k FREQUENCY (Hz)
10k
100k
Figure 22. Noise Spectral Density with Additional 250 Hz Filter
TEMPERATURE OUTPUT AND CALIBRATION
It is common practice to temperature-calibrate gyroscopes to improve their overall accuracy. The ADXRS623 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 25C and VRATIO = 5 V. The temperature coefficient is ~9 mV/C at 25C. Although the TEMP output is highly repeatable, it has only modest absolute accuracy.
VTEMP VRATIO
08890-023
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 ADXRS623 rate response. The -3 dB frequency set by ROUT and COUT is
f OUT =
(2 x x ROUT x COUT )
1
and can be well controlled because ROUT is trimmed during manufacturing to be 180 k 1%. Any external resistor applied between the RATEOUT pin (1B, 2A) and the SUMJ pin (1C, 2C) results in
ROUT =
(180 k x REXT ) (180 k + REXT )
RFIXED
RTEMP
Figure 23. ADXRS623 Temperature Sensor Structure
In general, an additional hardware or software filter is added to attenuate high frequency noise arising from demodulation spikes at the gyroscope'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, the corner frequency of this additional filter is set to greater than 5x the required bandwidth to preserve good phase response.
CALIBRATED PERFORMANCE
Using a three-point calibration technique, it is possible to calibrate the null and sensitivity drift of the ADXRS623 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
08890-022
0.000001 10
ADXRS623
ADXRS623 AND SUPPLY RATIOMETRICITY
The ADXRS623 RATEOUT and TEMP signals are ratiometric to the VRATIO voltage; that is, the null voltage, rate sensitivity, and temperature outputs are proportional to VRATIO. Thus, the ADXRS623 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 behavior. Typical ratiometricity error for null, sensitivity, selftest, 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 ST1 Mean Sigma ST2 Mean Sigma Null Mean Sigma Sensitivity Mean Sigma VTEMP Mean Sigma VS = VRATIO = 4.85 V 0.3% 0.21% -0.15% 0.22% -0.3% 0.2% 0.003% 0.06% -0.2% 0.05% VS = VRATIO = 5.15 V 0.09% 0.19% -0.2% 0.2% -0.05% 0.08% -0.25% 0.06% -0.04% 0.06%
SELF-TEST FUNCTION
The ADXRS623 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 -1.0 V, and ST2 causes an opposite change of +1.0 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 x VRATIO to the ST1 and ST2 pins. ST1 and ST2 are deactivated by applying a voltage of less than 0.2 x VRATIO to the ST1 and ST2 pins. The voltage applied to ST1 and ST2 must never be greater than AVCC.
CONTINUOUS SELF-TEST
The one-chip integration of the ADXRS623 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 about continuous self-test techniques are available in the AN-768 Application Note, Using the ADXRS150/ADXRS300 in Continuous Self-Test Mode, available at www.analog.com.
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.
Rev. 0 | Page 10 of 12
ADXRS623 OUTLINE DIMENSIONS
A1 BALL CORNER 7.05 6.85 SQ 6.70 *A1 CORNER INDEX AREA
7 6 5 4 3 2 1 A
4.80 BSC SQ 0.80 BSC
B C D E F G
TOP VIEW DETAIL A 3.80 MAX
BOTTOM VIEW
DETAIL A
0.60 MAX 0.25 MIN
3.20 MAX 2.50 MIN
SEATING PLANE
0.60 0.55 0.50
COPLANARITY 0.15
BALL DIAMETER *BALL A1 IDENTIFIER IS GOLD PLATED AND CONNECTED TO THE D/A PAD INTERNALLY VIA HOLES.
Figure 24. 32-Lead Ceramic Ball Grid Array [CBGA] (BG-32-3) Dimensions shown in millimeters
ORDERING GUIDE
Model1 ADXRS623WBBGZ ADXRS623WBBGZ-RL EVAL-ADXRS623Z
1
Temperature Range -40C to +105C -40C to +105C
Package Description 32-Lead Ceramic Ball Grid Array (CBGA) 32-Lead Ceramic Ball Grid Array (CBGA) Evaluation Board
10-26-2009-B
Package Option BG-32-3 BG-32-3
Z = RoHS Compliant Part.
Rev. 0 | Page 11 of 12
ADXRS623 NOTES
(c)2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D08890-0-3/10(0)
Rev. 0 | Page 12 of 12

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