High Temperature, Vibration Rejecting ±2000°/sec Gyroscope ADXRS645 Data Sheet FEATURES GENERAL DESCRIPTION Innovative ceramic vertical mount package can be oriented for pitch or roll rate response Wide temperature range: −40°C to +175°C Long life: guaranteed 1000 hours at TA = 175°C High vibration rejection over wide frequency 10,000 g powered shock survivability Ratiometric to referenced supply 5 V single-supply operation Self-test on digital command Temperature sensor output The ADXRS645 is a high performance angular rate sensor with excellent vibration immunity for use in high temperature environments. The ADXRS645 is manufactured using the Analog Devices, Inc., patented high volume BiMOS surfacemicromachining process with years of proven field reliability. An advanced, differential, quad sensor design provides superior acceleration and vibration rejection. The output signal, RATEOUT, is a voltage proportional to the angular rate about the axis normal to the package lid. The measurement range is a minimum of ±2000°/sec, and may be extended to ±5000°/sec with the addition of a single external resistor. The output is ratiometric with respect to a provided reference supply. Other external capacitors are required for operation. APPLICATIONS Down hole measurements for geological exploration Extreme high temperature industrial applications Severe mechanical environments 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 ADXRS645 is available in a 8 mm × 9 mm × 3 mm, 15-lead brazed lead tri in-line package. FUNCTIONAL BLOCK DIAGRAM 5V (ADC REF) 100nF 5V ST2 ST1 TEMP AVCC 100nF SELF-TEST 25kΩ @ 25°C VRATIO ADXRS645 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 11958-001 CP1 CP2 CP3 CP4 CP5 Figure 1. Rev. A Document Feedback 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 ©2014 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com ADXRS645 Data Sheet 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 Supply Ratiometricity ...................................................................9 Revision History ............................................................................... 2 Range Extension ............................................................................9 Specifications..................................................................................... 3 Self-Test Function .........................................................................9 Absolute Maximum Ratings ............................................................ 4 Continuous Self-Test.....................................................................9 Rate Sensitive Axis ....................................................................... 4 Outline Dimensions ....................................................................... 10 ESD Caution .................................................................................. 4 Ordering Guide .......................................................................... 10 Pin Configuration and Function Descriptions ............................. 5 Typical Performance Characteristics ............................................. 6 REVISION HISTORY 9/14—Rev. 0 to Rev. A Changes to Features Section............................................................ 1 Added Usable Life Expectancy Parameter, Table 1 ...................... 3 7/14—Revision 0: Initial Version Rev. A | Page 2 of 10 Data Sheet ADXRS645 SPECIFICATIONS All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed. TA = 25°C, VS = AVCC = VDD = 5 V, VRATIO = AVCC, angular rate = 0°/sec, bandwidth = 80 Hz (COUT = 0.01 µF), and IOUT = 100 µA, unless otherwise noted. Table 1. Parameter SENSITIVITY 1 Measurement Range 2, 3 Initial Temperature Drift Nonlinearity NULL1 Initial Temperature Drift Linear Acceleration Effect Vibration Rectification NOISE PERFORMANCE Rate Noise Density Resolution Floor FREQUENCY RESPONSE Bandwidth (±3 dB) 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 VTEMP at 25°C Scale Factor 7 TURN-ON TIME 8 OUTPUT DRIVE CAPABILITY Current Drive Capacitive Load Drive POWER SUPPLY Operating Voltage (VS) Quiescent Supply Current TEMPERATURE RANGE Specified Performance LIFESPAN Usable Life Expectancy Test Conditions/Comments Clockwise rotation is positive output Min Max ±2000 1 ±5 −35 0.1 TA = 25°C Uncompensated, −40°C to +150°C 4 Uncompensated, 150°C to 175°C Best fit straight line TA = 25°C Uncompensated, −40°C to +150°C4 Uncompensated, 150°C to 175°C Any axis 25 g rms, 50 Hz to 5 kHz Typ 2.4 TA ≤ 25°C TA = 25°C, 1 minute to 1 hour in-run TA = 150°C, 1 minute to 1 hour in-run 2.5 ±50 ±150 0.1 0.0006 °/sec mV/°/sec % % % of FS 2.6 0.25 100 150 No external filter 15.5 ST1 pin from Logic 0 to Logic 1 ST2 pin from Logic 0 to Logic 1 2000 17.5 20 Hz kHz 1.7 100 °/sec °/sec % V V kΩ 3.3 40 50 Load = 10 MΩ 25°C, VRATIO = 5 V Power on to ±2°/sec of final with CP5 = 100 nF 2.3 2.4 9 50 For rated specifications 4.75 −40 TA = 175°C 1000 5.00 3.5 V °/sec °/sec °/sec/g °/sec/g2 °/sec/√Hz °/hr °/hr −1300 1300 ±2 To common Unit 2.5 V mV/°C ms 200 1000 µA pF 5.25 V mA +175 °C Hours 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. Measurement range can be extended to as much as ±5000°/s by adding a single 120 kΩ resistor between the RATEOUT and SUMJ pins. 4 Maximum deviation from +25°C to −40°C or +25°C to +150°C, see the Typical Performance Characteristics section for typical behavior over temperature. 5 Adjusted by the 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. 8 Based on characterization. 1 2 3 Rev. A | Page 3 of 10 ADXRS645 Data Sheet 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 10,000 g 10,000 g −0.3 V to +6.6 V AVCC AVCC Indefinite The ADXRS645 produces a positive output voltage for clockwise rotation about the axis normal to the package lid, that is, clockwise when looking at the package lid. Z-AXIS + RATE AXIS −55°C to +175°C −65°C to +185°C Stresses at or above those listed under Absolute Maximum Ratings may cause permanent damage to the product. This is a stress rating only; functional operation of the product at these or any other conditions above those indicated in the operational section of this specification is not implied. Operation beyond the maximum operating conditions for extended periods may affect product reliability. 11958-002 Table 2. 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. Exercise care in handling to avoid damage. Rev. A | Page 4 of 10 Data Sheet ADXRS645 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS ST1 A VDD PGND RATEOUT SUMJ VRATIO 2 A B C D E F 1 A B C D E F CP4 CP1 CP2 AVCC AGND TEMP C CP5 ST2 B CP3 3 11958-003 ADXRS645 TOP VIEW (Not to Scale) 11958-200 Figure 3. Pin Configuration (Top View) Figure 4. Pin Configuration (3D View) Table 3. Pin Function Descriptions Pin Number A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 E1 E2 F1 F2 Mnemonic CP3 CP5 ST1 CP4 VDD ST2 CP1 PGND TEMP CP2 RATEOUT AVCC SUMJ AGND VRATIO Description Charge Pump Capacitor, 22 nF HV Filter Capacitor, 100 nF Positive Self-Test Charge Pump Capacitor, 22 nF Positive Charge Pump Supply Negative Self-Test Charge Pump Capacitor, 22 nF Charge Pump Supply Return Temperature Voltage Output Charge Pump Capacitor, 22 nF Rate Signal Output Positive Analog Supply Output Amplifier Summing Junction Analog Supply Return Reference Supply for Ratiometric Output Rev. A | Page 5 of 10 ADXRS645 Data Sheet TYPICAL PERFORMANCE CHARACTERISTICS 2700 2650 40 NULL OUTPUT (mV) 30 20 10 2600 2550 2500 2450 2400 –50 NULL OUTPUT (mV) 11958-104 2600 2585 2570 2555 2540 2525 2510 2495 2480 2465 2450 0 0 50 100 150 200 TEMPERATURE (°C) Figure 5. Null Output at 25°C 11958-107 PERCENTAGE OF POPULATION (%) 50 Figure 8. Null Output Over Temperature 1.2 50 1.0 40 SENSITIVITY (mV/°/sec) PERCENTAGE OF POPULATION (%) 45 35 30 25 20 15 10 0.8 0.6 0.4 0.2 0 –50 SENSITIVITY (mV/°/sec) 11958-105 1.18 1.15 1.12 1.09 1.06 1.03 1.00 0.97 0.94 0.91 0.88 0 0 50 100 150 200 TEMPERATURE (°C) 11958-108 5 Figure 9. Sensitivity Over Temperature Figure 6. Sensitivity at 25°C 0 35 –400 ST1 OUTPUT (°/sec) 25 20 15 10 –600 –800 –1000 –1200 –1400 –1600 5 0 50 100 150 TEMPERATURE (°C) Figure 10. ST1 Output Over Temperature Figure 7. ST1 Output Change at 25°C (VRATIO = 5 V) Rev. A | Page 6 of 10 200 11958-109 –2000 –50 11958-106 ST1 OUTPUT CHANGE (°/sec) –1100 –1150 –1200 –1250 –1300 –1350 –1400 –1450 –1500 0 –1550 –1800 –1600 PERCENTAGE OF POPULATION (%) –200 30 Data Sheet ADXRS645 2000 1800 35 1600 30 ST2 OUTPUT (°/sec) 25 20 15 1400 1200 1000 800 600 10 400 5 200 0 –50 ST2 OUTPUT CHANGE (°/sec) 11958-110 1700 1650 1600 1550 1500 1450 1400 1350 1300 1250 1200 0 0 50 100 150 200 TEMPERATURE (°C) 11958-113 PERCENTAGE OF POPULATION (%) 40 Figure 14. ST2 Output Over Temperature Figure 11. ST2 Output Change at 25°C (VRATIO = 5 V) 10000 45 35 ALLAN VARIANCE (°/Hour) PERCENTAGE OF POPULATION (%) 40 30 25 20 15 10 1000 AVERAGE +1σ 100 –1σ 10 1 0.01 SELF-TEST MISMATCH (%) 11958-111 3.0 2.5 2.0 1.5 1.0 0.5 0 –0.5 –1.0 –1.5 –2.0 0 1 10 100 1000 10000 AVERAGING TIME (Seconds) Figure 12. Self-Test Mismatch at 25°C (VRATIO = 5 V) Figure 15. Allan Variance at 25°C vs. Averaging Time 4.0 40 35 3.5 VTEMP OUTPUT (V) 30 25 20 15 3.0 2.5 10 2.0 1.5 –50 2.58 2.56 11958-112 VTEMP OUTPUT (V) 2.54 2.52 2.50 2.48 2.46 2.44 2.42 2.40 0 0 50 100 150 TEMPERATURE (°C) Figure 16. VTEMP Output Over Temperature Figure 13. VTEMP Output at 25°C Rev. A | Page 7 of 10 200 11958-115 5 2.38 PERCENTAGE OF POPULATION (%) 0.1 11958-114 5 ADXRS645 Data Sheet 0 20 15 10 5 11958-116 4150 4050 3950 3850 3750 3650 3550 3450 3350 3250 3150 –30 –6 –60 –9 –90 –12 –120 –15 –150 –18 0.1 0 CURRENT CONSUMPTION (mA) –3 –180 10 1 FREQUENCY (kHz) Figure 17. Current Consumption at 25°C (VRATIO = 5 V) Figure 19. Typical Rate and Phase Response vs. Frequency (COUT = 470 pF with a Series RC Low-Pass Filter of 3.3 kΩ and 22 nF) 1 0.04 0.03 NONLINEARITY (%FS) 0.02 0.1 0.01 0.01 0 0.01 0.02 0.03 0.04 1 10 100 1k FREQUENCY (Hz) 10k Figure 18. Typical Noise Spectral Density (COUT = 0.01 µF) 0.06 –2000 –1000 0 1000 RATE (°/sec) Figure 20. Typical Output Nonlinearity Rev. A | Page 8 of 10 2000 11958-019 0.05 0.001 0.1 11958-117 NOISE SPECTRAL DENSITY (°/sec/√Hz) PHASE (Degrees) 25 0 11958-018 30 RATE RESPONSE (dB) PERCENTAGE OF POPULATION (%) 35 Data Sheet ADXRS645 THEORY OF OPERATION The ADXRS645 operates on the principle of a resonator gyroscope. 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. The electrostatic resonator requires 15 V for operation. Because only 5 V is typically available in most applications, a charge pump is included on chip. If an external 17 V to 22 V supply is available, the two capacitors on CP1 to CP4 can be omitted, and this supply can be connected to CP5 (Pin A2) through a 1 kΩ series resistor. Do not ground CP5 when power is applied to the ADXRS645. 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 ADXRS645. SETTING BANDWIDTH The external capacitor, COUT, is used in combination with the on-chip resistor, ROUT, to create a low-pass filter to limit the bandwidth of the ADXRS645 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 (D2) and SUMJ pin (E2) 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 gyroscope. An RC output filter consisting of a 3.3 kΩ series resistor and 22 nF shunt capacitor (2.2 kHz pole) is recommended. TEMPERATURE OUTPUT AND CALIBRATION It is common practice to temperature calibrate gyroscopes to improve their overall accuracy. The ADXRS645 has a temperature proportional voltage output that provides input to such a calibration method. The temperature sensor structure is shown in Figure 21. SUPPLY RATIOMETRICITY The RATEOUT, ST1, ST2, and TEMP signals of the ADXRS645 are ratiometric to the VRATIO voltage, that is, the null voltage, rate sensitivity, and temperature outputs are proportional to VRATIO. Therefore, it is most easily used with a supply ratiometric analogto-digital converter (ADC), which results in self cancellation of errors due to minor supply variations. There is some small, usually negligible, error due to nonratiometric behavior. Note that, to guarantee full rate range, VRATIO must not be greater than AVCC. RANGE EXTENSION The ADXRS645 scale factor can be reduced to extend the measurement range to as much as ±5000°/sec by adding a single 120 kΩ resistor between the RATEOUT and SUMJ pins. If an external resistor is added between the RATEOUT and SUMJ pins, proportionally increase COUT to maintain correct bandwidth (that is, if adding a 180 kΩ resistor, double COUT). SELF-TEST FUNCTION The ADXRS645 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. It is activated by standard logic high levels applied to ST1 (Pin A3), ST2 (Pin B3), or both. ST1 causes the voltage at RATEOUT to change about −1.3 V, and ST2 causes an opposite change of +1.3 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 (±1%), 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 ADXRS645 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. The voltage at TEMP (Pin C3) is nominally 2.4 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 RTEMP 11958-010 RFIXED VTEMP Figure 21. Temperature Sensor Structure Rev. A | Page 9 of 10 ADXRS645 Data Sheet OUTLINE DIMENSIONS 8.20 8.00 7.80 FRONT VIEW 3.30 SIDE VIEW 2.85 2.40 BACK VIEW 5.00 BSC 9.20 9.00 8.80 0.30 0.25 0.20 6.30 6.00 5.70 1.30 BSC 1.48 1.35 1.22 3.00 BSC 2.00 BSC 2.83 2.70 2.57 01-07-2014-A PKG-004255 0.55 0.50 0.45 0.625 BSC TOP VIEW Figure 22. 15-Lead Brazed Lead Tri In-line Package [BL_TIP] (DY-15-1) Dimensions shown in millimeters ORDERING GUIDE Model 1 ADXRS645HDYZ 1 Temperature Range −40°C to +175°C Package Description 15-Lead Brazed Lead Tri In-line Package [BL_TIP] Z = RoHS Compliant Part. ©2014 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D11958-0-9/14(A) Rev. A | Page 10 of 10 Package Option DY-15-1