±50°/s Yaw Rate Gyro ADXRS624 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 (<0.15 cc, <0.5 gram) Temperature sensor output RoHS compliant Qualified for automotive applications The ADXRS624 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 angular rate about the axis normal to the top surface of the package. The output is ratiometric with respect to a provided reference supply. A single external resistor between SUMJ and RATEOUT can be used to lower the scale factor. An external capacitor sets the bandwidth. Other external capacitors are required for operation. APPLICATIONS Navigation systems Inertial measurement units Platform stabilization Robotics 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 ADXRS624 is available in a 7 mm × 7 mm × 3 mm BGA chip scale package. FUNCTIONAL BLOCK DIAGRAM +5V (ADC REF) 100nF +5V ST2 ST1 TEMP SELF-TEST 25kΩ AT 25°C AVCC 100nF VRATIO ADXRS624 ADXRS624 25kΩ AGND DEMOD MECHANICAL SENSOR DRIVE AMP +5V AC AMP VGA 200kΩ ±5% VDD CHARGE PUMP AND VOLTAGE REGULATOR 100nF PGND SUMJ RATEOUT 100nF 22nF 22nF COUT 08999-001 CP1 CP2 CP3 CP4 CP5 Figure 1. ADXRS624 Block Diagram Rev. A 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. ADXRS624 TABLE OF CONTENTS Features .............................................................................................. 1 Theory of Operation .........................................................................9 Applications ....................................................................................... 1 Setting Bandwidth .........................................................................9 General Description ......................................................................... 1 Temperature Output and Calibration .........................................9 Functional Block Diagram .............................................................. 1 Calibrated Performance ................................................................9 Revision History ............................................................................... 2 ADXRS624 and Supply Ratiometricity ......................................9 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 Typical Performance Characteristics ............................................. 6 Automotive Products ................................................................. 11 REVISION HISTORY 9/10—Rev. 0 to Rev. A Changes to Ordering Guide .......................................................... 11 4/10—Revision 0: Initial Version Rev. A | Page 2 of 12 ADXRS624 SPECIFICATIONS All minimum and maximum specifications are guaranteed; typical specifications are not guaranteed. At TA = −40°C to +105°C, VS = AVCC = VDD = 5 V, VRATIO = AVCC, angular rate = 0°/s, bandwidth = 80 Hz (COUT = 0.01 µF), IOUT = 100 μA, ±1 g, unless otherwise noted. Table 1. Parameter SENSITIVITY (RATIOMETRIC) 1 Measurement Range2 Initial and Over Temperature Temperature Drift3 Nonlinearity NULL (RATIOMETRIC)1 Null Linear Acceleration Effect NOISE PERFORMANCE Rate Noise Density FREQUENCY RESPONSE Bandwidth4 Sensor Resonant Frequency SELF-TEST (RATIOMETRIC)1 ST1 Rate-Out Response ST2 Rate-Out Response Logic 1 Input Voltage Logic 0 Input Voltage Input Impedance TEMPERATURE SENSOR (RATIOMETRIC)1 VOUT at 25°C 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 Conditions Clockwise rotation is positive output Full-scale range over specifications range Min ADXRS624BBGZ Typ Max ±50 22.5 Unit Best fit straight line ±75 25 ±3 0.1 −40°C to +105°C Any axis 2.5 0.1 V °/sec/g TA = 25°C 0.04 °/sec/√Hz 1 27.5 1000 14.5 ST1 pin from Logic 0 to Logic 1 ST2 pin from Logic 0 to Logic 1 −1.9 1.9 0.8 × VRATIO 0.2 × VRATIO To common 50 Load = 100 MΩ At 25°C, VRATIO = 5 V 2.35 V V V V kΩ Power on to ±½°/sec of final 50 For rated specifications 200 1000 µA pF 5.25 VS 5.0 V V mA +105 °C 5.00 3.5 –40 1 2.65 Hz kHz V mV/°C kΩ kΩ ms 4.75 3 2.5 9 25 25 °/sec mV/°/sec % % of FS 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. From +25°C to −40°C or from +25°C to +105°C. 4 Adjusted by the external capacitor, COUT. 5 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 3 Rev. A | Page 3 of 12 ADXRS624 ABSOLUTE MAXIMUM RATINGS RATE-SENSITIVE AXIS 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 Rating 2000 g 2000 g –0.3 V to +6.0 V AVCC Indefinite –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. The ADXRS624 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 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. A | Page 4 of 12 08999-002 Table 2. ADXRS624 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 08999-003 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. A | Page 5 of 12 ADXRS624 TYPICAL PERFORMANCE CHARACTERISTICS N > 1000 for all typical performance plots, unless otherwise noted. 35 45 40 PERCENT OF POPULATION (%) 25 20 15 10 5 35 30 25 20 15 10 5 30 35 10 08999-007 8 6 4 2 0 –1.30 –1.35 –1.40 –1.45 –1.50 –1.55 –1.60 –1.65 –1.70 –2.10 ST1 Δ (V) Figure 5. Null Drift over Temperature (VRATIO = 5 V) 08999-008 RATEOUT TEMPCO (°/sec/°C) 08999-005 0.30 0.25 0.20 0.15 0.10 0.05 0 –0.05 0 –0.10 0 –0.15 5 –1.75 10 5 –0.20 –2 15 –1.80 10 20 –1.85 15 25 –1.90 20 30 –1.95 25 –2.00 PERCENT OF POPULATION (%) 40 –0.25 –4 Figure 7. Sensitivity Drift over Temperature 35 –0.30 –6 SENSITIVITY DRIFT (%) Figure 4. Null Output at 25°C (VRATIO = 5 V) PERCENT OF POPULATION (%) –8 –10 3.4 RATEOUT (V) 0 08999-004 3.3 3.2 3.1 3.0 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0 1.9 1.8 1.7 1.6 0 –2.05 PERCENT OF POPULATION (%) 30 Figure 8. ST1 Output Change at 25°C (VRATIO = 5 V) 40 30 PERCENT OF POPULATION (%) 20 15 10 5 30 25 20 15 10 5 ST2 Δ (V) Figure 9. ST2 Output Change at 25°C (VRATIO = 5 V) Figure 6. Sensitivity at 25°C (VRATIO = 5 V) Rev. A | Page 6 of 12 2.10 08999-009 2.05 2.00 1.95 1.90 1.85 1.80 1.75 1.70 1.65 1.60 1.55 1.50 1.45 1.40 1.30 08999-006 27.50 27.25 27.00 26.75 26.50 26.25 26.00 25.75 25.50 25.25 25.00 24.75 24.25 24.50 SENSITIVITY (mV/°/sec) 1.35 0 0 24.00 PERCENT OF POPULATION (%) 35 25 ADXRS624 40 30 35 PERCENT OF POPULATION (%) PERCENT OF POPULATION (%) 25 20 15 10 5 30 25 20 15 10 0 08999-010 98 94 90 86 82 78 74 70 66 62 58 54 50 0 MEASUREMENT RANGE (°/sec) 2.40 2.42 2.44 2.46 2.48 2.50 2.52 2.54 2.56 2.58 2.60 VTEMP OUTPUT (V) Figure 10. Measurement Range Figure 13. VTEMP Output at 25°C (VRATIO = 5 V) 2.5 3.3 2.0 3.1 1.5 2.9 VTEMP OUTPUT (V) 1.0 SELF-TEST Δ (V) 08999-013 5 0.5 0 –0.5 –1.0 2.7 2.5 2.3 2.1 1.9 –1.5 1.7 –2.0 0 20 40 60 80 100 120 TEMPERATURE (ºC) 1.5 –40 08999-011 –20 –20 0 20 40 60 80 100 120 TEMPERATURE (°C) 08999-014 256 PARTS –2.5 –40 Figure 14. VTEMP Output over Temperature (VRATIO = 5 V) Figure 11. Typical Self-Test Change over Temperature 60 30 REF Y 25 X 40 +45° –45° 20 g OR °/s 30 15 20 10 10 0 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. A | Page 7 of 12 850 08999-015 (mA) –20 750 08999-012 0 –10 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 4.4 4.5 PERCENT OF POPULATION (%) 50 ADXRS624 0.10 2.0 LATITUDE LONGITUDE RATE 1.8 1.6 1.2 (°/s) PEAK RATEOUT (°/s) 0.05 1.4 1.0 0 0.8 0.6 –0.05 0.4 1k FREQUENCY (Hz) 10k –0.10 08999-016 0 100 0 20 40 60 80 100 120 140 TIME (Hours) 08999-019 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) 0.10 400 300 DUT1 OFFSET BY +200°/s 0.05 200 (°/s) (°/s) 100 0 0 –100 DUT2 OFFSET BY –200°/s –200 –0.05 0 50 100 150 200 250 (ms) –0.10 08999-017 –400 0 600 1200 1800 2400 3000 3600 TIME (Seconds) Figure 17. Typical High g (2500 g) Shock Response (Sensor Bandwidth = 40 Hz) 08999-020 –300 Figure 20. Typical Shift in Short Term Null (Bandwidth = 1 Hz) 0.1 0.1 0.01 (°/s rms) (°/s/ Hz rms) 1 0.01 1 10 100 1k 10k 100k AVERAGE TIME (Seconds) 0.0001 10 100 1k 10k 100k (Hz) Figure 18. Typical Root Allan Deviation at 25°C vs. Averaging Time Figure 21. Typical Noise Spectral Density (Bandwidth = 40 Hz) Rev. A | Page 8 of 12 08999-021 0.1 08999-018 0.001 0.01 0.001 ADXRS624 THEORY OF OPERATION 0.1 0.01 (°/s/ Hz rms) 0.001 0.0001 0.00001 0.000001 10 100 1k 10k 100k (Hz) 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 ADXRS624. 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 ADXRS624. SETTING BANDWIDTH TEMPERATURE OUTPUT AND CALIBRATION It is common practice to temperature-calibrate gyros to improve their overall accuracy. The ADXRS624 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. 1 VTEMP (2 × π × ROUT × COUT ) (200 kΩ × REXT ) (200 kΩ + REXT ) 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. Figure 22 shows the effect of adding a 250 Hz filter to the output of an ADXRS624 set to 40 Hz bandwidth (as shown in Figure 21). High frequency demodulation artifacts are attenuated by approximately 18 dB. RFIXED RTEMP 08999-023 VRATIO and can be well controlled because ROUT is trimmed during manufacture to be 200 kΩ ± 1%. Any external resistor applied between the RATEOUT pin (1B, 2A) and SUMJ pin (1C, 2C) results in ROUT = Figure 22. Noise Spectral Density with Additional 250 Hz Filter 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. External Capacitor COUT is used in combination with the onchip ROUT resistor to create a low-pass filter to limit the bandwidth of the ADXRS624 rate response. The –3 dB frequency set by ROUT and COUT is fOUT = 08999-022 The ADXRS624 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. ADXRS624 Temperature Sensor Structure CALIBRATED PERFORMANCE Using a three-point calibration technique, it is possible to calibrate the null and sensitivity drift of the ADXRS624 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. ADXRS624 AND SUPPLY RATIOMETRICITY The ADXRS624 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 ADXRS624 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 Rev. A | Page 9 of 12 ADXRS624 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 = 4.75 V VS = VRATIO = 5.25 V −0.4% 0.6% −0.3% 0.6% −0.4% 0.6% −0.3% 0.6% −0.04% 0.3% −0.02% 0.2% 0.03% 0.1% 0.1% 0.1% −0.3% 0.1% −0.5% 0.1% SELF-TEST FUNCTION The ADXRS624 includes a self-test feature that actuates each of the sensing structures and associated electronics as if subjected to angular rate. The self-test feature 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 −1.9 V, and ST2 causes an opposite change of +1.9 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 × VRATIO to the ST1 and ST2 pins. ST1 and ST2 are deactivated by applying a voltage of less than 0.2 × VRATIO to the ST1 and ST2 pins. The voltage applied to ST1 and ST2 must never be greater than AVCC. CONTINUOUS SELF-TEST 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. The one-chip integration of the ADXRS624 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. Rev. A | Page 10 of 12 ADXRS624 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 ADXRS624BBGZ ADXRS624BBGZ-RL ADXRS624WBBGZ ADXRS624WBBGZ-RL EVAL-ADXRS624Z 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 ADXRS624WBBGZ 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. A | Page 11 of 12 ADXRS624 NOTES ©2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D08999-0-9/10(A) Rev. A | Page 12 of 12