Fast Starting, ±20,000°/sec Vibration Rejecting Rate Gyro ADXRS649 FEATURES GENERAL DESCRIPTION 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 −40°C to +105°C operation Self-test on digital command Ultrasmall and light (<0.15 cc, <0.5 gram) Temperature sensor output RoHS compliant 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. APPLICATIONS 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. Sports equipment Industrial applications Platform stabilization High speed tachometry 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 × 7 mm × 3 mm CBGA chip scale package. FUNCTIONAL BLOCK DIAGRAM 5V (ADC REF) 100nF 5V ST2 ST1 TEMP SELF-TEST 25kΩ AT 25°C MECHANICAL SENSOR AC AMP VRATIO AVCC 100nF AGND ADXRS649 25kΩ DEMOD DRIVE AMP ROUT 180kΩ ±1% VDD 100nF PGND CHARGE PUMP AND VOLTAGE REGULATOR CP1 CP2 CP3 CP4 CP5 SUMJ 2.2nF 22nF 22nF RATEOUT COUT 09573-001 5V VGA 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 ©2010 Analog Devices, Inc. All rights reserved. ADXRS649 TABLE OF CONTENTS Features .............................................................................................. 1 Typical Performance Characteristics ..............................................6 Applications....................................................................................... 1 Theory of Operation .........................................................................9 General Description ......................................................................... 1 Setting Bandwidth.........................................................................9 Functional Block Diagram .............................................................. 1 Temperature Output and Calibration...................................... 10 Revision History ............................................................................... 2 Modifying the measurement range.......................................... 10 Specifications..................................................................................... 3 Null Adjustment ......................................................................... 10 Absolute Maximum Ratings............................................................ 4 Self-Test Function ...................................................................... 10 Rate Sensitive Axis ....................................................................... 4 Continuous Self-Test.................................................................. 10 ESD Caution.................................................................................. 4 Outline Dimensions ....................................................................... 11 Pin Configuration and Function Descriptions............................. 5 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 = −40°C to +105°C, VS = AVCC = VDD = VRATIO = 5 V, angular rate = 0°/sec, bandwidth = 80 Hz (COUT = 0.01 μF), IOUT = 100 μA, ±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 25°C 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 Test Conditions/Comments Clockwise rotation is positive output Full-scale range over specifications range −40°C to +105°C Min 0.08 Best fit straight line −40°C to +105°C −40°C to +105°C Any axis 40 g rms, 50 Hz to 27 kHz 2.4 TA = 25°C TA = 105°C TA = 25°C, 1 minute to 1 hour in-run Typ ±20,000 0.1 ±2 0.1 2.5 ±5 0.1 0.0006 Max 0.12 2.6 0.25 0.4 200 ±3 dB user adjustable up to specification 16 ST1 pin from Logic 0 to Logic 1 ST2 pin from Logic 0 to Logic 1 2000 18 50 Load = 10 MΩ TA = 25°C, VRATIO = 5 V 2.3 2.4 9 25 25 3 Power on to ±90% of final output, CP5 = 2.2 nF For rated specifications 4.75 −40 1 5.00 3.5 V °/sec °/sec/g °/sec/g2 20 Hz kHz 1.7 100 °/sec °/sec % V V kΩ 3.3 40 °/sec mV/°/sec % % of FS °/sec/√Hz °/sec/√Hz °/hr −1300 1300 ±2 To common Unit 2.5 V mV/°C kΩ kΩ ms 200 1000 μA pF 5.25 V mA +105 °C 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 +25°C to −40°C or +25°C to +105°C. 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 25°C to 26°C. VTEMP is ratiometric to VRATIO. See the Temperature Output and Calibration section for more information. 2 3 Rev. 0 | Page 3 of 12 ADXRS649 ABSOLUTE MAXIMUM RATINGS RATE SENSITIVE AXIS Table 2. 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. Rating 10,000 g 10,000 g −0.3 V to +6.0 V AVCC AVCC Indefinite RATE AXIS −55°C to +125°C −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. LONGITUDINAL AXIS RATEOUT AVCC = 5V 4.75V + VRATIO/2 7 RATE IN 1 A1 0.25V ABCDE FG LATERAL AXIS GND Figure 2. RATEOUT Signal Increases with Clockwise Rotation ESD CAUTION 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. Rev. 0 | Page 4 of 12 09573-002 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 ADXRS649 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS VDD PGND CP5 CP3 CP4 7 6 ST1 CP1 5 ST2 CP2 4 AVCC 3 TEMP 2 1 G F VRATIO NC SUMJ E D C RATEOUT B A NOTES 1. NC = NO CONNECT. DO NOT CONNECT TO THIS PIN. 09573-003 AGND 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. 60 –3 –30 50 –6 –60 40 –9 –90 –12 –120 –15 –150 20 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) 09573-007 FREQUENCY (kHz) Figure 7. Null Bias at 25°C Figure 4. Typical Rate and Phase Response vs. Frequency (COUT = 470 pF with a Series RC Low-Pass Filter of 3.3 kΩ and 22 nF) 4.0 60 3.5 50 POPULATION (%) RATE OUT (V) 3.0 2.5 2.0 1.5 40 30 20 1.0 10 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 TIME (ms) 0 09573-005 0 0.081 0.085 0.089 0.093 0.097 0.101 0.105 0.109 0.113 0.117 SENSITIVITY (mV/°/sec) Figure 5. Typical Start-Up Behavior at RATEOUT 09573-008 0.5 Figure 8. Sensitivity at 25°C 10000 100 POPULATION (%) 80 1000 60 40 100 0.01 0.1 1 10 100 1000 TIME (Seconds) Figure 6. Typical Root Allan Deviation at 25°C vs. Averaging Time 0 –100 –500 –300 –900 –1300 –1700 –2100 –700 –1100 –1500 –1900 –2300 DEGREES PER SECOND (°) Figure 9. ST1 Output Change at 25°C (VRATIO = 5 V) Rev. 0 | Page 6 of 12 09573-009 20 09573-006 DEGREES PER HOUR (°) RATE RESPONSE (dB) PHASE (Degrees) –180 10 1 30 10 09573-004 –18 0.1 POPULATION (%) 0 0 ADXRS649 30 100 25 POPULATION (%) 60 40 20 15 10 5 100 500 300 900 1300 1700 2100 700 1100 1500 1900 2300 DEGREES PER SECOND (°) 0 09573-010 0 20 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) 09573-013 POPULATION (%) 80 Figure 13. VTEMP Output at 25°C (VRATIO = 5 V) Figure 10. ST2 Output Change at 25°C (VRATIO = 5 V) 3.3 70 3.1 60 2.9 VTEMP OUTPUT (V) POPULATION (%) 50 40 30 2.7 2.5 2.3 2.1 20 1.9 10 1.7 –5 –4 –3 –2 –1 0 1 2 3 4 5 MISMATCH (%) 1.5 –50 09573-011 0 –25 0 25 50 75 09573-014 70 100 TEMPERATURE (°C) Figure 11. Self-Test Mismatch at 25°C (VRATIO = 5 V) Figure 14. VTEMP Output over Temperature, 256 Parts (VRATIO = 5 V) 1 30 ACCELERATION 25 g²/Hz AND %/sec 20 15 10 0.01 GYRO OUTPUT 0.001 0 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) Figure 12. Current Consumption at 25°C (VRATIO = 5 V) 0.0001 100 1000 FREQUENCY (Hz) 10000 09573-015 5 09573-012 POPULATION (%) 0.1 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 ADXRS649 0.5 10 0.4 0.3 NONLINEARITY (%) RATEOUT (°/sec Peak) 1 0.1 0.2 0.1 0 –0.1 –0.2 0.01 –0.3 1000 10000 VIBRATION INPUT FREQUENCY (Hz) –0.5 0 5000 10000 15000 ANGULAR RATE (Degress per Second) Figure 17. Typical Nonlinearity (Four Typical Devices) Figure 16. Typical Response to 10 g RMS Sinusoidal Vibration (Sensor Bandwidth = 1 kHz) Rev. 0 | Page 8 of 12 20000 09573-017 0.001 100 09573-016 –0.4 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 × π × ROUT × COUT) fOUT can be well controlled because ROUT has been trimmed during manufacturing to be 180 kΩ ± 1%. Any external resistor applied between the RATEOUT pin (B1, A2) and the SUMJ pin (C1, C2) results in ROUT = (180 kΩ × REXT)/(180 kΩ + 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 kΩ series resistor and 22 nF shunt capacitor (2.2 kHz pole) is recommended. X Y 09573-018 Z Figure 18. Simplified Gyro Sensing Structure—One Corner Rev. 0 | Page 9 of 12 ADXRS649 TEMPERATURE OUTPUT AND CALIBRATION SELF-TEST FUNCTION 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 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. The voltage at TEMP (F3, G3) is nominally 2.5 V at 25°C, and VRATIO = 5 V. The temperature coefficient is ~9 mV/°C at 25°C. Although the TEMP output is highly repeatable, it has only modest absolute accuracy. VRATIO TEMP RTEMP 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. 09573-019 RFIXED 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. Figure 19. Temperature Sensor Structure MODIFYING THE MEASUREMENT RANGE CONTINUOUS SELF-TEST The ADXRS649 scale factor can be reduced to extend the measurement range to as much as ±50,000°/sec by adding a single 120 kΩ 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. 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 B 4.80 BSC SQ 0.80 BSC C D E F G TOP VIEW BOTTOM VIEW DETAIL A 3.80 MAX 0.60 0.55 0.50 SEATING PLANE 3.20 MAX 2.50 MIN COPLANARITY 0.15 BALL DIAMETER *BALL A1 IDENTIFIER IS GOLD PLATED AND CONNECTED TO THE D/A PAD INTERNALLY VIA HOLES. 10-26-2009-B DETAIL A 0.60 MAX 0.25 MIN 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 –40°C to +105°C Package Description 32-Lead Ceramic Ball Grid Array [CBGA] Evaluation Board Z = RoHS Compliant Part. Rev. 0 | Page 11 of 12 Package Option BG-32-3 ADXRS649 NOTES ©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