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Fast Starting, 20,000/sec Vibration Rejecting Rate Gyro ADXRS649
FEATURES
High vibration rejection over wide frequency Ultrafast startup: 3 ms Measurement range extendable to 50,000/sec 10,000 g powered shock survivability Ratiometric to referenced supply 5 V single-supply operation Z-axis (yaw rate) response -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 ADXRS649 is a complete angular rate sensor (gyroscope) that uses the Analog Devices, Inc., patented high volume BiMOS surface-micromachining process to make a complete gyro on one chip. An advanced, differential, quad sensor design rejects the influence of linear acceleration, enabling the ADXRS649 to offer rate sensing in harsh environments where shock and vibration are present. The output signal, RATEOUT (B1, A2), is a voltage proportional to the angular rate about the axis normal to the top surface of the package. The output is ratiometric with respect to a provided reference supply. An external capacitor is used to set the bandwidth. The measurement range is extendable to 50,000/sec by adding an external resistor. Low power consumption (3.5 mA) enables very low power consumption, and ultrafast startup (3 ms) allows for quick power cycling of the gyro. At 10 samples per second, a pair of CR2032 coin cells can power the ADXRS649 for three months. 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 ADXRS649 is available in a 7 mm x 7 mm x 3 mm CBGA chip scale package.
APPLICATIONS
Sports equipment Industrial applications Platform stabilization High speed tachometry
FUNCTIONAL BLOCK DIAGRAM
5V (ADC REF) 100nF 5V AVCC 100nF AGND SELF-TEST
25k AT 25C
ST2
ST1
TEMP
VRATIO
ADXRS649
25k
DEMOD
DRIVE AMP
MECHANICAL SENSOR
AC AMP
VGA
5V
VDD
ROUT 180k 1% CHARGE PUMP AND VOLTAGE REGULATOR SUMJ 2.2nF 22nF 22nF RATEOUT
09573-001
100nF PGND
CP1 CP2 CP3 CP4 CP5
COUT
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.
ADXRS649 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...................................... 10 Modifying the measurement range.......................................... 10 Null Adjustment ......................................................................... 10 Self-Test Function ...................................................................... 10 Continuous Self-Test.................................................................. 10 Outline Dimensions ....................................................................... 11 Ordering Guide .......................................................................... 11
REVISION HISTORY
12/10--Revision 0: Initial Version
Rev. 0 | Page 2 of 12
ADXRS649 SPECIFICATIONS
All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed. TA = -40C to +105C, VS = AVCC = VDD = VRATIO = 5 V, angular rate = 0/sec, bandwidth = 80 Hz (COUT = 0.01 F), IOUT = 100 A, 1 g, unless otherwise noted. Table 1.
Parameter SENSITIVITY 1 Measurement Range 2 Initial and over Temperature Temperature Drift 3 Nonlinearity NULL BIAS1 Null Bias Calibrated Null Bias 4 Linear Acceleration Effect Vibration Rectification NOISE PERFORMANCE Rate Noise Density Resolution Floor FREQUENCY RESPONSE Bandwidth 5 Sensor Resonant Frequency SELF-TEST1 ST1 RATEOUT Response ST2 RATEOUT Response ST1 to ST2 Mismatch 6 Logic 1 Input Voltage Logic 0 Input Voltage Input Impedance TEMPERATURE SENSOR1 VOUT at 25C Scale Factor 7 Load to VS Load to Common TURN-ON TIME4 OUTPUT DRIVE CAPABILITY Current Drive Capacitive Load Drive POWER SUPPLY Operating Voltage (VS) Quiescent Supply Current TEMPERATURE RANGE Specified Performance
1 2 3
Test Conditions/Comments Clockwise rotation is positive output Full-scale range over specifications range -40C to +105C Best fit straight line -40C to +105C -40C to +105C Any axis 40 g rms, 50 Hz to 27 kHz TA = 25C TA = 105C TA = 25C, 1 minute to 1 hour in-run 3 dB user adjustable up to specification
Min
Typ 20,000 0.1 2 0.1 2.5 5 0.1 0.0006 0.25 0.4 200 2000 18 -1300 1300 2
Max
Unit /sec mV//sec % % of FS V /sec /sec/g /sec/g2 /sec/Hz /sec/Hz /hr Hz kHz /sec /sec % V V k V mV/C k k ms A pF V mA C
0.08
0.12
2.4
2.6
16 ST1 pin from Logic 0 to Logic 1 ST2 pin from Logic 0 to Logic 1 3.3 To common Load = 10 M TA = 25C, VRATIO = 5 V 40 2.3
20
50 2.4 9 25 25 3
1.7 100 2.5
Power on to 90% of final output, CP5 = 2.2 nF For rated specifications
200 1000 4.75 5.00 3.5 5.25
-40
+105
Parameter is linearly ratiometric with VRATIO. Measurement range is the maximum range possible, including output swing range, initial offset, sensitivity, offset drift, and sensitivity drift at 5 V supplies. From +25C to -40C or +25C to +105C. 4 Based on characterization. 5 Adjusted by external capacitor, COUT. Reducing bandwidth below 0.01 Hz does not result in further noise improvement. 6 Self-test mismatch is described as (ST2 + ST1)/((ST2 - ST1)/2). 7 Scale factor for a change in temperature from 25C to 26C. VTEMP is ratiometric to VRATIO. See the Temperature Output and Calibration section for more information.
Rev. 0 | Page 3 of 12
ADXRS649 ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Acceleration (Any Axis, 0.5 ms) Unpowered Powered VDD, AVCC VRATIO ST1, ST2 Output Short-Circuit Duration (Any Pin to Common) Operating Temperature Range Storage Temperature Range Rating 10,000 g 10,000 g -0.3 V to +6.0 V AVCC AVCC Indefinite -55C to +125C -65C to +150C
RATE SENSITIVE AXIS
The ADXRS649 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 RATEOUT AVCC = 5V 4.75V + 7 1 A1 ABCDE FG LATERAL AXIS
LONGITUDINAL AXIS
VRATIO/2
RATE IN
09573-002
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.
0.25V
GND
Figure 2. RATEOUT Signal Increases with Clockwise Rotation
ESD CAUTION
Rev. 0 | Page 4 of 12
ADXRS649 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
09573-003
RATEOUT
NOTES 1. NC = NO CONNECT. DO NOT CONNECT TO THIS PIN.
Figure 3. Pin Configuration
Table 3. Pin Function Descriptions
Pin No. D6, D7 A6, B7 C6, C7 A5, B5 A4, B4 A3, B3 B1, A2 C1, C2 D1, D2 E1, E2 F1, G2 F3, G3 F4, G4 F5, G5 G6, F7 E6, E7 Mnemonic CP5 CP4 CP3 CP1 CP2 AVCC RATEOUT SUMJ NC VRATIO AGND TEMP ST2 ST1 PGND VDD Description High Voltage Filter Capacitor, 2.2 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. Do not connect to these pins. 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
ADXRS649 TYPICAL PERFORMANCE CHARACTERISTICS
N > 1000 for all histograms, unless otherwise noted.
0 0
60
-3
-30
50
RATE RESPONSE (dB)
-9
-90
POPULATION (%)
09573-004
PHASE (Degrees)
-6
-60
40
30
-12
-120
20
-15
-150
10
FREQUENCY (kHz)
Figure 4. Typical Rate and Phase Response vs. Frequency (COUT = 470 pF with a Series RC Low-Pass Filter of 3.3 k and 22 nF)
4.0 3.5 50 3.0 2.5 2.0 1.5 1.0 10 0.5 0 0
POPULATION (%)
Figure 7. Null Bias at 25C
60
40
RATE OUT (V)
30
20
09573-005
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0.081 0.085 0.089 0.093 0.097 0.101 0.105 0.109 0.113 0.117 SENSITIVITY (mV//sec)
TIME (ms)
Figure 5. Typical Start-Up Behavior at RATEOUT
10000
100
Figure 8. Sensitivity at 25C
80
DEGREES PER HOUR ()
POPULATION (%)
60
1000
40
20
09573-006
TIME (Seconds)
-300
Figure 6. Typical Root Allan Deviation at 25C vs. Averaging Time
Figure 9. ST1 Output Change at 25C (VRATIO = 5 V)
Rev. 0 | Page 6 of 12
09573-009
100 0.01
0
0.1
1
10
100
1000
-100
-500
-900 -1300 -1700 -2100 -700 -1100 -1500 -1900 -2300 DEGREES PER SECOND ()
09573-008
09573-007
-18 0.1
1
-180 10
0 2.401 2.434 2.467 2.500 2.533 2.566 2.599 2.451 2.418 2.484 2.517 2.550 2.583 NULL BIAS (V)
ADXRS649
100
30
80
25
POPULATION (%)
60
POPULATION (%)
20
15
40
10
20
5
100 300
500
900 1300 1700 2100 700 1100 1500 1900 2300 DEGREES PER SECOND ()
09573-010
2.35 2.37 2.39 2.41 2.43 2.45 2.47 2.49 2.51 2.53 2.55 VTEMP OUTPUT (V)
Figure 10. ST2 Output Change at 25C (VRATIO = 5 V)
70 60 50 POPULATION (%) 40 30 20
Figure 13. VTEMP Output at 25C (VRATIO = 5 V)
3.3 3.1 2.9
VTEMP OUTPUT (V)
2.7 2.5 2.3 2.1 1.9
10
70
1.7
09573-014
09573-011
0
-5
-4
-3
-2
-1
0
1
2
3
4
5
1.5 -50
-25
0
25
50
75
100
MISMATCH (%)
TEMPERATURE (C)
Figure 11. Self-Test Mismatch at 25C (VRATIO = 5 V)
30
Figure 14. VTEMP Output over Temperature, 256 Parts (VRATIO = 5 V)
1
25
0.1
ACCELERATION
POPULATION (%)
g/Hz AND %/sec
20
15
0.01
GYRO OUTPUT
10
0.001
5
3.06
3.15
3.24
3.42 3.60 3.78 3.96 4.14 3.33 3.51 3.69 3.87 4.05 4.23 CURRENT CONSUMPTION (mA)
09573-012
1000 FREQUENCY (Hz)
10000
Figure 12. Current Consumption at 25C (VRATIO = 5 V)
Figure 15. Typical Response to 25 g RMS Random Vibration, 50 Hz to 5 kHz (Sensor Bandwidth = 1 kHz)
Rev. 0 | Page 7 of 12
09573-015
0
0.0001 100
09573-013
0
0
ADXRS649
10
0.5 0.4 0.3
1
RATEOUT (/sec Peak)
NONLINEARITY (%)
0.2 0.1 0 -0.1 -0.2 -0.3 -0.4
09573-016
0.1
0.01
1000 VIBRATION INPUT FREQUENCY (Hz)
10000
0
5000
10000
15000
20000
ANGULAR RATE (Degress per Second)
Figure 16. Typical Response to 10 g RMS Sinusoidal Vibration (Sensor Bandwidth = 1 kHz)
Figure 17. Typical Nonlinearity (Four Typical Devices)
Rev. 0 | Page 8 of 12
09573-017
0.001 100
-0.5
ADXRS649 THEORY OF OPERATION
The ADXRS649 operates on the principle of a resonator gyro. Figure 18 shows a simplified version of one of four polysilicon sensing structures. Each sensing structure contains a dither frame that is electrostatically driven to resonance. This produces the necessary velocity element to produce a Coriolis force when experiencing angular rate. The ADXRS649 is designed to sense a z-axis (yaw) angular rate. When the sensing structure is exposed to angular rate, the resulting Coriolis force couples into an outer sense frame, which contains movable fingers that are placed between fixed pickoff fingers. This forms 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 quad sensor design rejects linear and angular acceleration, including external g-forces and vibration. This is achieved by mechanically coupling the four sensing structures such that external g-forces appear as common-mode signals that can be removed by the fully differential architecture implemented in the ADXRS649. The electrostatic resonator requires 13 V to 15 V for operation. Because only 5 V are typically available in most applications, a charge pump is included on chip. If an external 13 V to 15 V supply is available, the two capacitors on CP1 to CP4 can be omitted, and this supply can be connected to CP5 (Pin D6, Pin D7). CP5 should not be grounded when power is applied to the ADXRS649. 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 ADXRS649.
SETTING THE BANDWIDTH
External Capacitor COUT is used in combination with the onchip ROUT resistor to create a low-pass filter to limit the bandwidth of the ADXRS649 rate response. The -3 dB frequency set by ROUT and COUT is fOUT = 1/(2 x x ROUT x COUT) fOUT can be well controlled because ROUT has been trimmed during manufacturing to be 180 k 1%. Any external resistor applied between the RATEOUT pin (B1, A2) and the SUMJ pin (C1, C2) results in ROUT = (180 k x REXT)/(180 k + REXT) In general, an additional filter (in either hardware or software) is added to attenuate high frequency noise arising from demodulation spikes at the 18 kHz resonant frequency of the gyro. An RC output filter consisting of a 3.3 k series resistor and 22 nF shunt capacitor (2.2 kHz pole) is recommended.
X
Y Z
Figure 18. Simplified Gyro Sensing Structure--One Corner
Rev. 0 | Page 9 of 12
09573-018
ADXRS649
TEMPERATURE OUTPUT AND CALIBRATION
It is common practice to temperature-calibrate gyros to improve their overall accuracy. The ADXRS649 has a temperature proportional voltage output that provides input to such a calibration method. The temperature sensor structure is shown in Figure 19. 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 (F3, G3) 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.
VRATIO TEMP
09573-019
SELF-TEST FUNCTION
The ADXRS649 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. The self-test is activated by standard logic high levels applied to Input ST1 (F5, G5), Input ST2 (F4, G4), or both. ST1 causes the voltage at RATEOUT to change by approximately -0.15 V, and ST2 causes an opposite change of +0.15 V. The self-test response follows the viscosity temperature dependence of the package atmosphere, approximately 0.25%/C. Activating ST1 and ST2 simultaneously does not damage the part. ST1 and ST2 are fairly closely matched (2%), 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.
RFIXED
RTEMP
Figure 19. Temperature Sensor Structure
MODIFYING THE MEASUREMENT RANGE
The ADXRS649 scale factor can be reduced to extend the measurement range to as much as 50,000/sec by adding a single 120 k resistor between the RATEOUT and SUMJ pins. If an external resistor is added between RATEOUT and SUMJ, COUT must be proportionally increased to maintain correct bandwidth.
CONTINUOUS SELF-TEST
The on-chip integration of the ADXRS649 gives it higher reliability than is obtainable with any other high volume manufacturing method. In addition, it is manufactured under a mature BiMOS process that has 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. Information about continuous self-test techniques is also available in the AN-768 Application Note, Using the ADXRS150/ADXRS300 in Continuous Self-Test Mode.
NULL BIAS ADJUSTMENT
The nominal 2.5 V null bias is for a symmetrical swing range at RATEOUT (B1, A2). However, a nonsymmetric output swing may be suitable in some applications. Null bias adjustment is possible by injecting a suitable current to SUMJ (C1, C2). Note that supply disturbances may reflect some null bias instability. Digital supply noise should be avoided, particularly in this case.
Rev. 0 | Page 10 of 12
ADXRS649 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 20. 32-Lead Ceramic Ball Grid Array [CBGA] (BG-32-3) Dimensions shown in millimeters
ORDERING GUIDE
Model 1 ADXRS649BBGZ-RL EVAL-ADXRS649Z
1
Temperature Range -40C to +105C
Package Description 32-Lead Ceramic Ball Grid Array [CBGA] Evaluation Board
10-26-2009-B
Package Option BG-32-3
Z = RoHS Compliant Part.
Rev. 0 | Page 11 of 12
ADXRS649 NOTES
(c)2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D09573-0-12/10(0)
Rev. 0 | Page 12 of 12

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