±50°/s Yaw Rate Gyro ADXRS614 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 The ADXRS614 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 ADXRS614 is available in a 7 mm × 7 mm × 3 mm BGA chip scale package. FUNCTIONAL BLOCK DIAGRAM +5V (ADC REF) +5V ST2 AVCC 100nF ST1 SELF-TEST TEMP 25kΩ @ 25°C VRATIO 100nF ADXRS614 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 06748-001 CP1 CP2 CP3 CP4 CP5 Figure 1. ADXRS614 Block Diagram 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 ©2007 Analog Devices, Inc. All rights reserved. ADXRS614 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 ADXRS614 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 REVISION HISTORY 4/07—Revision 0: Initial Version Rev. 0 | Page 2 of 12 ADXRS614 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°/s, bandwidth = 80 Hz (COUT = 0.01 μF), IOUT = 100 μA, ±1 g, unless otherwise noted. Table 1. Parameter SENSITIVITY (Ratiometric) 1 Measurement Range 2 Initial and Over Temperature Temperature Drift 3 Nonlinearity NULL (Ratiometric)1 Null Linear Acceleration Effect NOISE PERFORMANCE Rate Noise Density FREQUENCY RESPONSE Bandwidth 4 Sensor Resonant Frequency SELF-TEST (Ratiometric)1 ST1 RATEOUT Response ST2 RATEOUT Response Logic 1 Input Voltage Logic 0 Input Voltage Input Impedance TEMPERATURE SENSOR (Ratiometric)1 VOUT at 25°C Scale Factor 5 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 ADXRS614BBGZ 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 @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 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. 0 | Page 3 of 12 ADXRS614 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 ADXRS614 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 A1 ABCDE FG 1 LATERAL AXIS 0.25V 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. 0 | Page 4 of 12 06748-002 Table 2. ADXRS614 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 06748-003 1 Figure 3. Pin Configuration Table 4. 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 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 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. 0 | Page 5 of 12 ADXRS614 TYPICAL PERFORMANCE CHARACTERISTICS N > 1000 for all typical performance plots, unless otherwise noted. 18 35 16 30 % OF POPULATION % OF POPULATION 14 12 10 8 6 25 20 15 10 4 VOLTS 06748-007 0 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 0 5 06748-004 2 –10–9 –8 –7 –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 7 8 9 10 DRIFT (%) Figure 4. Null Output at 25°C (VRATIO = 5 V) Figure 7. Sensitivity Drift over Temperature 30 40 35 25 % OF POPULATION % OF POPULATION 30 20 15 10 25 20 15 10 5 –0.6 –0.5 –0.4 –0.3 –0.2 –0.1 0 0.1 0.2 0.3 0.4 0.5 0 0.6 º/s/ºC 06748-008 06748-005 0 5 –2.5 –2.4 –2.3 –2.2 –2.1 –2 –1.9 –1.8 –1.7 –1.6 –1.5 –1.4 –1.3 VOLTS Figure 5. Null Drift over Temperature (VRATIO = 5 V) Figure 8. ST1 Output Change at 25°C (VRATIO = 5 V) 50 40 45 35 40 % OF POPULATION 30 25 20 15 25 20 15 10 10 0 22 22.5 23 23.5 24 24.5 25 25.5 26 26.5 27 27.5 28 mV/º/s 06748-009 5 0 5 06748-006 % OF POPULATION 30 35 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5 VOLTS Figure 6. Sensitivity at 25°C (VRATIO = 5 V) Figure 9. ST2 Output Change at 25°C (VRATIO = 5 V) Rev. 0 | Page 6 of 12 14 40 12 35 30 10 % OF POPULATION 8 6 4 20 15 10 5 06748-010 2 0 25 50 54 58 62 66 70 74 78 82 86 90 94 0 98 2.40 2.42 2.44 2.46 2.48 2.50 2.52 2.54 2.56 2.58 2.60 º/s VOLTS Figure 10 .Measurement Range 06748-013 % OF POPULATION ADXRS614 Figure 13. VTEMP Output at 25°C (VRATIO = 5 V) 2.5 3.3 2 3.1 1.5 2.9 1 2.7 VOLTS 0 –0.5 2.5 2.3 2.1 –1 1.9 –1.5 –20 0 20 40 60 80 100 256 PARTS 1.5 –40 120 –20 0 20 40 60 80 100 120 06748-014 –2.5 –40 1.7 06748-011 –2 850 06748-015 VOLTS 0.5 TEMPERATURE (°C) TEMPERATURE (ºC) Figure 14. VTEMP Output over Temperature (VRATIO = 5 V) Figure 11. Typical Self-Test Change over Temperature 30 60 REF 50 25 Y X +45° –45° g OR °/s 30 15 20 10 10 0 5 06748-012 0 –10 –20 750 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 % OF POPULATION 40 20 (mA) 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. 0 | Page 7 of 12 ADXRS614 1.6 0.10 1.4 1.2 0.05 (°/s) (°/s) 1.0 0.8 0 0.6 –0.05 0.4 LAT LONG 0.2 (Hz) –0.10 06748-016 10k 1k 0 20 40 60 80 100 120 140 TIME (Hours) 06748-019 RATE 0 100 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) 400 0.10 300 DUT1 OFFSET BY +200°/s 200 0.05 (°/s) (°/s) 100 0 0 –100 DUT2 OFFSET BY –200°/s –200 –0.05 0 50 100 150 200 250 (ms) –0.10 06748-017 –400 0 600 1200 1800 2400 3000 3600 TIME (Seconds) Figure 17. Typical High g (2500 g) Shock Response (Sensor Bandwidth = 40 Hz) 06748-020 –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) Figure 18. Typical Root Allan Deviation at 25°C vs. Averaging Time 0.0001 10 100 1k 10k 100k (Hz) Figure 21. Typical Noise Spectral Density (Bandwidth = 40 Hz) Rev. 0 | Page 8 of 12 06748-021 0.1 06748-018 0.001 0.01 0.001 ADXRS614 THEORY OF OPERATION 0.1 0.01 (°/s/ Hz rms) 0.001 0.0001 0.00001 0.000001 10 100 10k 1k 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 ADXRS614. 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 ADXRS614. SETTING BANDWIDTH 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 ADXRS614 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. 1 (2 × π × ROUT × COUT ) VTEMP VRATIO and can be well controlled because ROUT has been trimmed during manufacturing to be 200 kΩ ±1%. Any external resistor applied between the RATEOUT pin (1B, 2A) and SUMJ pin (1C, 2C) results in: (200 kΩ × R EXT ) ROUT = (200 kΩ + R EXT ) 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 ADXRS614 set to 40 Hz bandwidth (as shown in Figure 21). High frequency demodulation artifacts are attenuated by approximately 18 dB. RFIXED RTEMP 06748-023 External Capacitor COUT is used in combination with the onchip ROUT resistor to create a low-pass filter to limit the bandwidth of the ADXRS614 rate response. The –3 dB frequency set by ROUT and COUT is: f OUT = 06748-022 The ADXRS614 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. ADXRS614 Temperature Sensor Structure CALIBRATED PERFORMANCE Using a 3-point calibration technique, it is possible to calibrate the null and sensitivity drift of the ADXRS614 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. ADXRS614 AND SUPPLY RATIOMETRICITY The ADXRS614 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 ADXRS614 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. 0 | Page 9 of 12 ADXRS614 behavior. Typical ratiometricity error for null, sensitivity, selftest, and temperature output is outlined in Table 3. Note that VRATIO must never be greater than AVCC. Table 3. 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 ADXRS614 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 −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 pin and the ST2 pin. 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 ADXRS614 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 a separate application note. Rev. 0 | Page 10 of 12 ADXRS614 OUTLINE DIMENSIONS *A1 CORNER INDEX AREA 7.05 6.85 SQ 6.70 7 6 5 4 3 2 A A1 BALL PAD INDICATOR TOP VIEW 1 B 4.80 BSC SQ C BOTTOM VIEW D E F G 0.80 BSC (BALL PITCH) DETAIL A 3.80 MAX SEATING PLANE 0.60 0.55 0.50 BALL DIAMETER 3.30 MAX 2.50 MIN COPLANARITY 0.15 *BALL A1 IDENTIFIER IS GOLD PLATED AND CONNECTED TO THE D/A PAD INTERNALLY VIA HOLES. 060506-A DETAIL A 0.60 0.25 Figure 24. 32-Lead Ceramic Ball Grid Array [CBGA] (BG-32-3) Dimensions shown in millimeters ORDERING GUIDE Model ADXRS614BBGZ1 ADXRS614BBGZ-RL1 EVAL-ADXRS614Z1 Temperature Range –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) Evaluation Board 1 Z = RoHS Compliant Part. Rev. 0 | Page 11 of 12 Package Option BG-32-3 BG-32-3 ADXRS614 NOTES ©2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D06748-0-4/07(0) Rev. 0 | Page 12 of 12