ADXRS622BBGZ

±250°/sec Yaw Rate Gyroscope ADXRS622 FEATURES GENERAL DESCRIPTION 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: 1000 for all typical performance plots, unless otherwise noted. 35 20 18 PERCENT OF POPULATION PERCENT OF POPULATION 30 16 14 12 10 8 6 4 25 20 15 10 5 2 10 07754-007 8 6 4 2 0 –2 –4 PERCENT CHANGE FROM 25°C Figure 7. Sensitivity Drift over Temperature Figure 4. Null Output at 25°C (VRATIO = 5 V) 40 70 35 15 –375 –400 –425 –450 –475 –500 –675 (mV) Figure 5. Null Drift over Temperature (VRATIO = 5 V) 07754-008 mV DRIFT FROM 25°C 07754-005 400 350 300 250 200 150 100 0 50 –50 –100 –150 –200 –250 0 –300 0 –350 5 –400 10 –525 10 –550 20 20 –575 30 25 –600 40 30 –625 50 –650 PERCENT OF POPULATION 60 PERCENT OF POPULATION –6 –10 2.80 07754-004 2.75 2.70 2.60 2.65 2.50 2.55 2.45 2.40 2.35 2.30 2.25 2.20 (V) –8 0 0 Figure 8. ST1 Output Change at 25°C (VRATIO = 5 V) 30 40 35 PERCENT OF POPULATION 20 15 10 30 25 20 15 10 5 5 0 (mV) Figure 6. Sensitivity at 25°C (VRATIO = 5 V) Figure 9. ST2 Output Change at 25°C (VRATIO = 5 V) Rev. C | Page 6 of 12 675 07754-009 650 625 600 575 550 525 500 475 450 425 400 375 7.8 7.7 07754-006 (mV/°/sec) 7.6 7.5 7.4 7.3 7.2 7.1 7.0 6.9 6.8 6.7 6.6 6.5 6.4 0 6.3 PERCENT OF POPULATION 25 ADXRS622 30 70 25 PERCENT OF POPULATION 50 40 30 20 20 15 10 5 10 0 2.55 (V) 07754-013 2.53 2.51 2.49 2.47 2.45 2.43 2.41 2.39 2.35 5 PERCENT MISMATCH 07754-010 4 3 2 1 0 –1 –2 –3 –4 –5 0 2.37 PERCENT OF POPULATION 60 Figure 13. VTEMP Output at 25°C (VRATIO = 5 V) Figure 10. Self-Test Mismatch at 25°C (VRATIO = 5 V) 3.3 600 3.1 400 2.9 ST2 2.7 200 (V) (mV) 2.5 0 2.3 2.1 200 ST1 1.9 400 –30 –10 10 30 50 TEMPERATURE (°C) 70 90 110 1.5 –50 07754-011 600 –50 Figure 11. Typical Self-Test Change over Temperature –25 0 25 50 TEMPERATURE (°C) 75 100 07754-114 1.7 Figure 14. VTEMP Output over Temperature, 256 Parts (VRATIO = 5 V) 30 60 REF 50 Y X 40 +45° 20 g OR °/sec –45° 15 30 20 10 10 0 5 (mA) 4.5 –20 750 07754-012 4.3 4.1 3.9 3.7 3.5 3.3 3.1 2.9 2.7 0 770 790 810 830 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. C | Page 7 of 12 850 07754-014 –10 2.5 PERCENT OF POPULATION 25 ADXRS622 0.10 2.0 LAT LONG RATE 1.8 1.6 1.2 (°/sec) PEAK RATEOUT (°/s) 0.05 1.4 1.0 0 0.8 0.6 –0.05 0.4 1k FREQUENCY (Hz) 10k –0.10 07754-116 0 100 0 20 40 60 80 100 120 140 TIME (Hours) Figure 16. Typical Response to 10 g Sinusoidal Vibration (Sensor Bandwidth = 40 Hz) 07754-018 0.2 Figure 19. Typical Shift in 90 sec Null Averages Accumulated over 140 Hours 400 0.10 300 DUT1 OFFSET BY +200°/sec 200 0.05 (°/sec) (°/sec) 100 0 0 –100 DUT2 OFFSET BY –200°/sec –200 –0.05 0 50 100 150 200 250 TIME (ms) –0.10 07754-016 –400 0 1200 1800 2400 3000 3600 TIME (Seconds) Figure 17. Typical High g (2500 g) Shock Response (Sensor Bandwidth = 40 Hz) Figure 20. Typical Shift in Short Term Null (Bandwidth = 1 Hz) 1 0.1 (°/sec rms) (°/sec/ Hz rms) 0.1 0.01 0.01 0.1 1 10 100 1k 10k 100k AVERAGING TIME (Seconds) 0.0001 10 100 1k 10k 100k (Hz) Figure 21. Typical Noise Spectral Density (Bandwidth = 40 Hz) Figure 18. Typical Root Allan Deviation at 25°C vs. Averaging Time Rev. C | Page 8 of 12 07754-020 0.001 07754-017 0.001 0.01 600 07754-019 –300 ADXRS622 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 ADXRS622 rate response. The −3 dB frequency set by ROUT and COUT is fOUT = 1/(2 × π × ROUT × COUT ) 0.01 0.0001 0.000001 10 100 1k 10k 100k (Hz) 07754-021 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 ADXRS622 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 its 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 and 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 ROUT = (180 kΩ × REXT )/(180 kΩ + REXT ) 0.001 RFIXED VTEMP RTEMP 07754-022 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 onchip. If an external 18 V to 20 V supply is available, the two capacitors on CP1 from 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 ADXRS622. Although no damage occurs, under certain conditions the charge pump may fail to start up after the ground is removed if power is not first removed from the ADXRS622. 0.1 (°/sec/ Hz rms) The ADXRS622 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 produce 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. ADXRS622 Temperature Sensor Structure CALIBRATED PERFORMANCE In general, an additional hardware or software filter is added to attenuate high frequency noise arising from demodulation spikes at the 14 kHz resonant frequency of the gyro. The noise spikes at 14 kHz can be clearly seen in the power spectral density curve, shown in Figure 21. Typically, this additional filter corner frequency is set to greater than 5× the required bandwidth to preserve good phase response. Using a three-point calibration technique, it is possible to calibrate the ADXRS622 null and sensitivity drift 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. Figure 22 shows the effect of adding a 250 Hz filter to the output of an ADXRS622 set to 40 Hz bandwidth (as shown in Figure 21). High frequency demodulation artifacts are attenuated by approximately 18 dB. Rev. C | Page 9 of 12 ADXRS622 ADXRS622 AND SUPPLY RATIOMETRICITY NULL ADJUSTMENT The ADXRS622 RATEOUT and TEMP signals are ratiometric to the VRATIO voltage, that is, the null voltage, rate sensitivity, and temperature outputs are proportional to VRATIO. Therefore, the ADXRS622 is most easily used with a supply-ratiometric analogto-digital converter (ADC) that results in self-cancellation of errors due to minor supply variations. The nominal 2.5 V null is for a symmetrical swing range at RATEOUT (1B, 2A). However, a nonsymmetric 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. There is some small error due to nonratiometric behavior. Typical ratiometricity error for null, sensitivity, self-test, and temperature output is outlined in Table 4. SELF-TEST FUNCTION 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% The ADXRS622 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 0.5 − V, and ST2 causes an opposite change of +0.5 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 pin and the ST2 pin. The voltage applied to ST1 and ST2 must never be greater than AVCC. CONTINUOUS SELF-TEST The on-chip integration of the ADXRS622 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, 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. Rev. C | Page 10 of 12 ADXRS622 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 ADXRS622BBGZ ADXRS622BBGZ-RL ADXRS622WBBGZA ADXRS622WBBGZA-RL EVAL-ADXRS622Z 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 ADXRS622W 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. C | Page 11 of 12 ADXRS622 NOTES ©2009–2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D07754-0-9/10(C) Rev. C | Page 12 of 12