±300°/sec Yaw Rate Gyro ADXRS620 FEATURES GENERAL DESCRIPTION Qualified for automotive applications 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 The ADXRS620 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 that is used for high reliability automotive airbag accelerometers. The ADXRS620 is an automotive grade gyroscope that is 100% pin, package, temperature, and function compatible to the available industrial grade ADXRS652 gyro. Automotive grade gyroscopes have more extensive guaranteed minimum/maximum specifications due to automotive testing. APPLICATIONS The output signal, RATEOUT (1B, 2A), is a voltage that is 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. An external capacitor sets the bandwidth. Other external capacitors are required for operation. Vehicle chassis rollover sensing Inertial measurement units Platform stabilization 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 ADXRS620 is available in a 7 mm × 7 mm × 3 mm BGA ceramic package. FUNCTIONAL BLOCK DIAGRAM +5V (ADC REF) 100nF +5V ST2 ST1 TEMP AVCC 100nF SELF-TEST 25kΩ @ 25°C VRATIO ADXRS620 25kΩ AGND DEMOD MECHANICAL SENSOR DRIVE AMP +5V AC AMP VGA 180kΩ ±1% VDD CHARGE PUMP AND VOLTAGE REGULATOR 100nF PGND SUMJ RATEOUT 100nF 22nF 22nF COUT 08887-001 CP1 CP2 CP3 CP4 CP5 Figure 1. Rev. B 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. www.analog.com Tel: 781.329.4700 Fax: 781.461.3113 ©2010 Analog Devices, Inc. All rights reserved. ADXRS620 TABLE OF CONTENTS Features .............................................................................................. 1 Setting Bandwidth .........................................................................9 Applications ....................................................................................... 1 Temperature Output and Calibration .........................................9 General Description ......................................................................... 1 Calibrated Performance ................................................................9 Functional Block Diagram .............................................................. 1 ADXRS620 and Supply Ratiometricity ................................... 10 Revision History ............................................................................... 2 Null Adjustment ......................................................................... 10 Specifications..................................................................................... 3 Self-Test Function ...................................................................... 10 Absolute Maximum Ratings ............................................................ 4 Continuous Self-Test.................................................................. 10 Rate Sensitive Axis ....................................................................... 4 Outline Dimensions ....................................................................... 11 ESD Caution .................................................................................. 4 Ordering Guide .......................................................................... 11 Pin Configuration and Function Descriptions ............................. 5 Automotive Products ................................................................. 11 Typical Performance Characteristics ............................................. 6 Theory of Operation ........................................................................ 9 REVISION HISTORY 9/10—Rev. A to Rev. B Changes to Ordering Guide .......................................................... 11 7/10—Rev. 0 to Rev. A Changes to Features Section and General Description Section . 1 Added Note 2 to Ordering Guide ................................................. 11 Added Automotive Products Section........................................... 11 3/10—Revision 0: Initial Version Rev. B | Page 2 of 12 ADXRS620 SPECIFICATIONS All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed. TA = −40°C to +105°C, VS = AVCC = VDD = 5 V, VRATIO = AVCC, 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 Range2 Initial and Over Temperature Temperature Drift3 Nonlinearity NULL1 Null Linear Acceleration Effect NOISE PERFORMANCE Rate Noise Density FREQUENCY RESPONSE Bandwidth4 Sensor Resonant Frequency SELF-TEST1 ST1 RATEOUT Response ST2 RATEOUT Response ST1 to ST2 Mismatch5 Logic 1 Input Voltage Logic 0 Input Voltage Input Impedance TEMPERATURE SENSOR1 VOUT at 25°C Scale Factor6 Load to VS Load to Common TURN-ON TIME OUTPUT DRIVE CAPABILITY Current Drive Capacitive Load Drive POWER SUPPLY Operating Voltage (VS) Quiescent Supply Current TEMPERATURE RANGE Specified Performance Conditions Clockwise rotation is positive output Full-scale range over specifications range −40°C to +105°C Min ±300 5.52 Best fit straight line −40°C to +105°C Any axis 2.2 TA ≤ 25°C Typ Max 6 ±2 0.1 6.48 2.5 0.1 2.8 0.05 0.01 12 14.5 ST1 pin from Logic 0 to Logic 1 ST2 pin from Logic 0 to Logic 1 −650 250 −5 3.3 −450 450 To common 40 50 Load = 10 MΩ @ 25°C, VRATIO = 5 V 2.35 2.5 9 25 25 Unit °/sec mV/°/sec % % of FS V °/sec/g °/sec/√Hz 2500 17 Hz kHz −250 650 +5 mV mV % V V kΩ 1.7 100 Power on to ±½°/sec of final 50 V mV/°C kΩ kΩ ms For rated specifications 200 1000 µA pF 5.25 4.5 V mA +105 °C 4.75 −40 1 5.00 3.5 2.65 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 +25°C to −40°C or from +25°C to 105°C. 4 Adjusted by external capacitor, COUT. Reducing bandwidth below 0.01 Hz does not reduce noise further. 5 Self-test mismatch is described as (ST2 + ST1)/((ST2 − ST1)/2). 6 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 details. 2 Rev. B | Page 3 of 12 ADXRS620 ABSOLUTE MAXIMUM RATINGS RATE SENSITIVE AXIS 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 2000 g 2000 g −0.3 V to +6.0 V AVCC AVCC Indefinite The ADXRS620 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 RATE OUT VCC = 5V LONGITUDINAL AXIS 4.75V + VRATIO/2 7 −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. 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 2000 g and can exceed the absolute maximum rating of the device. Exercise care during handling to avoid damage. Rev. B | Page 4 of 12 08887-002 Table 2. ADXRS620 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS VDD PGND CP5 CP3 CP4 7 6 ST1 CP1 5 ST2 CP2 4 AVCC 3 TEMP 2 AGND G F VRATIO NC SUMJ E D C RATEOUT B A 08887-003 1 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 (0.1 µF) 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 Amp 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. B | Page 5 of 12 ADXRS620 TYPICAL PERFORMANCE CHARACTERISTICS N > 1000 for all typical performance plots, unless otherwise noted. 30 20 PERCENTAGE OF POPULATION (%) PERCENTAGE OF POPULATION (%) 18 16 14 12 10 8 6 4 25 20 15 10 5 0 2.80 RATE OUT (V) –10 08887-004 2.75 2.70 2.65 2.60 2.55 2.50 2.45 2.40 2.35 2.30 2.25 2.20 0 –4 –2 0 2 4 6 8 10 Figure 7. Sensitivity Drift over Temperature 35 PERCENTAGE OF POPULATION (%) 40 35 30 25 20 15 10 5 –0.2 –0.1 0 0.1 0.2 0.3 0.4 0.5 (°/sec°/C) 25 20 15 10 5 0 –650 –610 –570 –530 –490 –450 –410 –370 –330 –290 –250 ST1 Δ (mV) Figure 8. ST1 Output Change at 25°C (VRATIO = 5 V) Figure 5. Null Drift over Temperature (VRATIO = 5 V) 40 14 35 PERCENTAGE OF POPULATION (%) 16 12 10 8 6 4 2 5.5 5.6 5.7 5.8 5.9 6 6.1 6.2 6.3 SENSITIVITY (mV/°/sec) 6.4 6.5 25 20 15 10 5 0 08887-006 0 30 250 290 330 370 410 450 490 530 570 610 ST2 Δ (mV) Figure 6. Sensitivity at 25°C (VRATIO = 5 V) Figure 9. ST2 Output Change at 25°C (VRATIO = 5 V) Rev. B | Page 6 of 12 650 08887-009 –0.4 –0.3 08887-005 0 –0.5 30 08887-008 45 PERCENTAGE OF POPULATION (%) –6 DRIFT (%) Figure 4. Null Output at 25°C (VRATIO = 5 V) % OF POPULATION –8 08887-007 2 70 40 60 35 50 40 30 20 10 –5 –4 –3 –2 –1 0 1 2 3 4 5 SELF-TEST MISMATCH (%) 25 20 15 10 5 0 08887-010 0 30 2.40 2.42 2.44 2.46 2.48 2.50 2.52 2.54 2.56 2.58 2.60 VOLTAGE (V) 08887-015 PERCENTAGE OF POPULATION (%) PERCENTAGE OF POPULATION (%) ADXRS620 Figure 13. VTEMP Output at 25°C (VRATIO = 5 V) Figure 10. Self-Test Mismatch at 25°C (VRATIO = 5 V) 600 3.3 3.1 400 ST2 200 VOLTAGE (V) 2.7 0 –200 2.5 2.3 2.1 1.9 –400 ST1 1.7 0 20 40 60 80 100 08887-011 –20 1.5 –40 120 TEMPERATURE (°C) –20 0 20 40 60 80 100 120 TEMPERATURE (°C) Figure 11. Typical Self-Test Change over Temperature 08887-013 256 PARTS –600 –40 Figure 14. VTEMP Output over Temperature (VRATIO = 5 V) 30 60 REF 50 25 Y X 40 +45° 20 g OR °/sec –45° 15 30 20 10 10 0 5 –20 750 0 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 CURRENT CONSUMPTION (m A) 4.5 770 790 810 830 TIME (ms) Figure 12. Current Consumption at 25°C (VRATIO = 5 V) Figure 15. g and g × g Sensitivity for a 50 g, 10 ms Pulse Rev. B | Page 7 of 12 850 08887-014 –10 08887-012 PERCENTAGE OF POPULATION (%) SELF-TEST Δ (mV) 2.9 ADXRS620 0.10 2.0 LAT LONG RATE 1.8 RATE OF ROTATION (°/sec) PEAK RATEOUT (°/s) 1.6 1.4 1.2 1.0 0.8 0.6 0.05 0 –0.05 0.4 1k FREQUENCY (Hz) 10k –0.10 08887-116 0 100 0 20 40 60 80 100 120 140 TIME (Hours) 08887-018 0.2 Figure 19. Typical Shift in 90 sec Null Averages Accumulated over 140 Hours Figure 16. Typical Response to 10 g Sinusoidal Vibration (Sensor Bandwidth = 2 kHz) 0.10 400 DUT1 OFFSET BY +200°/sec RATE OF ROTATION (°/sec) RATE OF ROTATION (°/sec) 300 200 100 0 –100 DUT2 OFFSET BY –200°/sec –200 0.05 0 –0.05 0 50 100 150 200 250 TIME (ms) –0.10 08887-016 –400 0 1800 2400 3000 3600 Figure 20. Typical Shift in Short-Term Null (Bandwidth = 1 Hz) 0.1 0.1 0.1 1 10 100 1k 10k 100k AVERAGE TIME (Seconds) 0.001 0.0001 10 08887-017 0.01 0.01 100 1k 10k 100k FREQUENCY (Hz) Figure 21. Typical Noise Spectral Density (Bandwidth = 40 Hz) Figure 18. Typical Root Allan Deviation at 25°C vs. Averaging Time Rev. B | Page 8 of 12 08887-020 NOISE SPECTRAL DENSITY(°/sec/√Hz rms) 1 ROOT ALLAN DEVIATION (°/sec rms) 1200 TIME (Seconds) Figure 17. Typical High g (2500 g) Shock Response (Sensor Bandwidth = 40 Hz) 0.001 0.01 600 08887-019 –300 ADXRS620 THEORY OF OPERATION SETTING 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 ADXRS620 rate response. The −3 dB frequency set by ROUT and COUT is fOUT = 1 (2 × π × ROUT × COUT ) This frequency can be well controlled because ROUT has been trimmed during manufacturing to be 180 kΩ ± 1%. Any external resistor applied between the RATEOUT pin (1B, 2A) and SUMJ pin (1C, 2C) results in (180 kΩ × REXT ) ROUT = (180 kΩ + REXT ) 0.1 0.01 0.001 0.0001 0.000001 10 100 1k 10k 100k FREQUENCY (Hz) 08887-021 0.00001 Figure 22. Noise Spectral Density with Additional 250 Hz Filter TEMPERATURE OUTPUT AND CALIBRATION It is common practice to temperature-calibrate gyros to improve their overall accuracy. The ADXRS620 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 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 RFIXED VTEMP RTEMP 08887-022 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 ADXRS620. 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 ADXRS620. Figure 22 shows the effect of adding a 250 Hz filter to the output of an ADXRS620 set to 40 Hz bandwidth (as shown in Figure 21). High frequency demodulation artifacts are attenuated by approximately 18 dB. NOISE SPECTRAL DENSITY(°/sec/√Hz rms) The ADXRS620 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 produces 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. Figure 23. Temperature Sensor Structure 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. CALIBRATED PERFORMANCE Using a three-point calibration technique, it is possible to calibrate the null and sensitivity drift of the ADXRS620 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. B | Page 9 of 12 ADXRS620 ADXRS620 AND SUPPLY RATIOMETRICITY NULL ADJUSTMENT The ADXRS620 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 ADXRS620 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. 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. 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 VS = VRATIO = 5.15 V 0.3% 0.21% 0.09% 0.19% −0.15% 0.22% −0.2% 0.2% −0.3% 0.2% −0.05% 0.08% 0.003% 0.06% −0.25% 0.06% −0.2% 0.05% −0.04% 0.06% SELF-TEST FUNCTION The ADXRS620 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 −0.450 V, and ST2 causes an opposite change of +0.450 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 equal to VRATIO to the ST1 and ST2 pins. The voltage applied to ST1 and ST2 must never be greater than AVCC. CONTINUOUS SELF-TEST The on-chip integration of the ADXRS620 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 the AN-768 Application Note at analog.com. Rev. B | Page 10 of 12 ADXRS620 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 24. 32-Lead Ceramic Ball Grid Array [CBGA] (BG-32-3) Dimensions shown in millimeters ORDERING GUIDE Model1, 2 ADXRS620BBGZ ADXRS620BBGZ-RL ADXRS620WBBGZA ADXRS620WBBGZA-RL EVAL-ADXRS620Z 1 2 Temperature Range –40°C to +105°C –40°C to +105°C –40°C to +105°C –40°C to +105°C Package Description 32-Lead Ceramic Ball Grid Array (CBGA) 32-Lead Ceramic Ball Grid Array (CBGA) 32-Lead Ceramic Ball Grid Array (CBGA) 32-Lead Ceramic Ball Grid Array (CBGA) Evaluation Board Package Option BG-32-3 BG-32-3 BG-32-3 BG-32-3 Z = RoHS Compliant Part. W = Qualified for Automotive Applications. AUTOMOTIVE PRODUCTS The ADXRS620W models are available with controlled manufacturing to support the quality and reliability requirements of automotive applications. Note that these automotive models may have specifications that differ from the commercial models; therefore, designers should review the Specifications section of this data sheet carefully. Only the automotive grade products shown are available for use in automotive applications. Contact your local Analog Devices account representative for specific product ordering information and to obtain the specific Automotive Reliability reports for these models. Rev. B | Page 11 of 12 ADXRS620 NOTES ©2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D08887-0-9/10(B) Rev. B | Page 12 of 12