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150/s single chip yaw rate gyro with signal conditioning adxrs150 features complete rate gyroscope on a single chip z-axis (yaw rate) response high vibration rejection over wide frequency 0.05/s/ hz noise 2000 g powered shock survivability self-test on digital command temperature sensor output precision voltage reference output absolute rate output for precision applications 5 v single-supply operation ultrasmall and light (< 0.15 cc, < 0.5 gram) applications gps navigation systems vehicle stability control inertial measurement units guidance and control platform stabilization general description the adxrs150 is a complete angular rate sensor (gyroscope) that uses analog devices surface-micromachining process to make a functionally complete and low cost angular rate sensor integrated with all of the 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 the angular rate about the axis normal to the top surface of the package (see figure 2). a single external resistor can be used to lower the scale factor. an external capacitor is used to set the bandwidth. other external capacitors are required for operation (see figure 22). a precision reference and a temperature output are also pro- vided for compensation techniques. two digital self-test inputs electromechanically excite the sensor to test the operation of both sensors and the signal conditioning circuits. the adxrs150 is available in a 7 mm 7 mm 3 mm bga surface-mount package. functional block diagram 5g 4g 3a 5v 2g 1f 7f 6a 7d 7c 7b 1c 4a 5a 7e 6g 1d 2a 1e 3g 1b pdd 12v + adxrs150 47nf 22nf 100nf 22nf cp2 cp1 pgnd cp4 cp3 cp5 charge pump/reg. temp ptat rateout 2.5v demod rate sensor self test 100nf 100nf cmid agnd avcc st1 st2 coriolis signal channel r sen1 r sen2 c out sumj r out 2.5v ref 9k ? 35% 9k ? 35% 180k ? 1% resonator loop ? 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 ri ghts of analog devices. trademarks and registered trademarks are the prop erty 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: 781.326.8703 ? 2004 analog devices, inc. all rights reserved.
adxrs150 rev. b | page 2 of 12 table of contents specifications..................................................................................... 3 absolute maximum ratings............................................................ 4 rate sensitive axis........................................................................ 4 esd caution.................................................................................. 4 pin configurations and function descriptions ........................... 5 typical performance characteristics ............................................. 6 theory of operation ........................................................................ 9 supply and common considerations ....................................... 9 setting bandwidth ........................................................................ 9 increasing measurement range ............................................... 10 temperature output and calibration...................................... 10 using the adxrs150 with a supply-ratiometric adc ...... 10 null adjustment ......................................................................... 10 self-test function ...................................................................... 10 continuous self-test.................................................................. 10 acceleration sensitivity ............................................................. 11 outline dimensions ....................................................................... 12 ordering guide .......................................................................... 12 revision history 3/04data sheet changed from rev. a to rev. b updated format..................................................................universal changes to table 1 conditions ....................................................... 3 added evaluation board to ordering guide .............................. 12 1/03data sheet changed from rev. 0 to rev. a edit to figure 5.................................................................................. 5
adxrs150 rev. b | page 3 of 12 specifications @t a = 25c, v s = 5 v, bandwidth = 80 hz (c out = 0.01 f), angular rate = 0/s, 1 g , unless otherwise noted. table 1. adxrs150abg parameter conditions min 1 typ max 1 unit sensitivity clockwise rotation is positive output dynamic range 2 full-scale range over specifications range 150 /s initial @25c 11.25 12.5 13.75 mv//s over temperature 3 v cc = 4.75 v to 5.25 v 11.25 13.75 mv//s nonlinearity best fit straight line 0.1 % of fs voltage sensitivity v cc = 4.75 v to 5.25 v 0.7 %/v null initial null 2.50 v null drift over temperature 3 delta from 25c 300 mv turn-on time power on to ?/s of final 35 ms linear acceleration effect any axis 0.2 /s/ g voltage sensitivity v cc = 4.75 v to 5.25 v 1 /s/v noise performance rate noise density @25c 0.05 /s/hz frequency response 3 db bandwidth 4 (user selectable) 22 nf as comp cap (s ee the applications section) 40 hz sensor resonant frequency 14 khz self test st1 rateout response 5 st1 pin from logic 0 to 1, C40c to +85c C400 C660 C1000 mv st2 rateout response 5 st2 pin from logic 0 to 1, C40c to +85c +400 +660 +1000 mv logic 1 input voltage standard high logic level definition 3.3 v logic 0 input voltage standard low logic level definition 1.7 v input impedance to common 50 k? temperature sensor v out at 298k 2.50 v max current load on pin source to common 50 a scale factor proportional to absolute temperature 8.4 mv/k output drive capability output voltage swing i out = 100 a 0.25 v s C 0.25 v capacitive load drive 1000 pf 2.5 v reference voltage value 2.45 2.5 2.55 v load drive to ground source 200 a load regulation 0 < i out < 200 a 5.0 mv/ma power supply rejection 4.75 v s to 5.25 v s 1.0 mv/v temperature drift 3 delta from 25c 5.0 mv power supply operating voltage range 4.75 5.00 5.25 v quiescent supply current 6.0 8.0 ma temperature range specified performance grade a C40 +85 c 1 all min and max specifications are guaranteed. ty pical specifications are not tested or guaranteed. 2 dynamic range is the maximum full-scale me asurement range possible, including output swing range, initial offset, sensitivity, offset drift, and sensitivity drift at 5 v supplies. 3 specification refers to the maximum extent of this parameter as a worst-case value at t min or t max . 4 frequency at which response is 3 db down from dc response with specified compensation capacitor value. internal pole forming r esistor is 180 k?. see the setting bandwidth section. 5 self-test response varies with temperature. see the self-test function section for details.
adxrs150 rev. b | page 4 of 12 absolute maximum ratings table 2. parameter rating acceleration (any axis , unpowered, 0.5 ms) 2000 g acceleration (any axis, powered, 0.5 ms) 2000 g +v s C0.3 v to +6.0 v output short-circuit duration (any pin to common) indefininte operating temperature range C55c to +125c storage temperature C65c to +150c stresses above those listed under absolute maximum ratings may cause permanent damage to the device. this is a stress rat- ing only and functional operation of the device at these or any other conditions above those indicated in the operational sec- tion of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. applications requiring more than 200 cycles to mil-std-883 method 1010 condition b (C55c to +125c) require underfill or other means to achieve this requirement. drops onto hard surfaces can cause shocks of greater than 2000 g and exceed the absolute maximum rating of the device. care should be exercised in handling to avoid damage. rate sensitive axis this is a z-axis rate-sensing device that is 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, i.e., clockwise when looking down at the package lid. 2.5v rate axis rateout rate in gnd 4.75v 0.25v lateral axis abcdefg 7 a1 1 longitudinal axis v cc = 5v figure 2. rateout signal incr eases with clockwise rotation esd caution esd (electrostatic discharge) sensitive device. electrosta tic charges as high as 4000 v readily accumulate on the human body and test equipment and can discharge with out detection. although this product features proprietary esd protection circuitry, permanent dama ge may occur on devices subjected to high energy electrostatic discharges. therefore, proper esd precautions are recommended to avoid performance degradation or loss of functionality.
adxrs150 rev. b | page 5 of 12 pin configuration and fu nction descriptions agnd temp st2 st1 pgnd avcc cp1 cp2 cp4 rateout gf ed cb a 7 6 5 4 3 2 1 cp5 cp3 pdd cmid sumj 2.5v 03226-b-003 figure 3. bga-32 (bottom view) table 3. pin function descriptions pin no. mnemonic description 6d, 7d cp5 hv filter capacitor47 nf 6a, 7b cp4 6c, 7c cp3 charge pump capacitor22 nf charge pump capacitor22 nf 5a, 5b cp1 4a, 4b cp2 charge pump capacitor22 nf charge pump capacitor22 nf 3a, 3b avcc + analog supply 1b, 2a rateout rate signal output 1c, 2c sumj output amp summing junction 1d, 2d cmid hf filter capacitor100 nf 1e, 2e 2.5v 2.5 v precision reference 1f, 2g agnd analog supply return 3f, 3g temp temperature voltage output 4f, 4g st2 self-test for sensor 2 5f, 5g st1 self-test for sensor 1 6g, 7f pgnd charge pump supply return 6e, 7e pdd + charge pump supply
adxrs150 rev. b | page 6 of 12 typical performance characteristics ?0.05 0.05 0.15 0.25 time (sec) rateout (v) 4.5 3.0 0 0.5 1.5 1.0 2.5 2.0 4.0 3.5 0 0.10 0.20 03226-b-004 figure 4. rate sensing start-up time 0 1200 2400 3600 time (sec) rateout (v) 2.570 2.540 2.545 2.555 2.550 2.565 2.560 600 1800 3000 figure 5. null stability for 1 hour ?55 ?5 45 95 temperature (c) v temp (v) 3.4 1.8 2.4 2.8 2.6 3.2 3.0 ?30 20 70 2.0 2.2 figure 6. temperature sensor output 0 60 120 180 time (sec) rateout (v) 2.570 2.540 2.545 2.555 2.550 2.565 2.560 30 90 150 no prior warmup, 0.6hz sampling figure 7. null settling time 1 100 time (sec) /s 0.07 0 0.02 0.01 0.04 0.03 10 0.06 0.05 figure 8. root allan variance vs. averaging time temperature (c) v2.5 (v) 2.5040 2.5010 2.5020 2.5015 2.5025 2.5035 2.5030 ?40 ?30 ?20 ?10 0 10 20 30 40 50 60 70 80 figure 9. 2.5 v voltage reference vs. temperature
adxrs150 rev. b | page 7 of 12 @ bw = 40 hz, typical vibration characteristics, 10 g flat band, 20 hz to 2 khz time (sec) rateout (v) 2.450 2.470 2.460 2.480 2.500 2.490 0 5 10 package lateral axis (1/60 sec sample rate) figure 10. 10 g random vibration in package-lateral axis orientation time (sec) rateout (v) 2.450 2.470 2.460 2.480 2.500 2.490 0 5 10 package longitudinal axis (1/60 sec sampling rate) figure 11. 10 g random vibration in package-longitudinal axis orientation time (sec) rateout (v) 2.450 2.470 2.460 2.480 2.500 2.490 0 5 10 rate axis (1/60 sec sampling rate) figure 12. 10 g random vibration in rate axis orientation time (sec) rateout (v) 2.450 2.470 2.460 2.480 2.500 2.490 0 5 10 package lateral axis (0.5s average) 10 g 0 g figure 13. 10 g random vibration in package-lateral axis orientation time (sec) rateout (v) 2.450 2.470 2.460 2.480 2.500 2.490 0 5 10 package longitudinal axis (0.5s average) 0 g 10 g figure 14. 10 g random vibration in package-longitudinal axis orientation time (sec) rateout (v) 2.450 2.470 2.460 2.480 2.500 2.490 0 5 10 rate axis (0.5s average) 0 g 10 g figure 15. 10 g random vibration in rate axis orientation
adxrs150 rev. b | page 8 of 12 behavior under various shock test conditions figure 16. shock test 100 g, 5 ms in lateral axis (40 hz) figure 17. hi-g shock test in lateral axis (40 hz) figure 18. hi-g shock in rate axis (40 hz) figure 19. shock test 100 g, 5 ms in longitudinal axis (40 hz) figure 20. hi-g shock test, lateral axis, 10 time base (40 hz) figure 21. hi-g shock, rate axis, bw reduced to 8 hz
adxrs150 rev. b | page 9 of 12 theory of operation the adxrs150 operates on the principle of a resonator gyro. two polysilicon sensing structures each contain a dither frame, which is electrostatically driven to resonance. this produces 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, movable fingers are placed between fixed pickoff fingers to form a capacitive pickoff struc- ture that senses coriolis motion. the resulting signal is fed to a series of gain and demodulation stages that produce the electri- cal 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 14 v to 16 v for operation. since only 5 v is typically available in most applications, a charge pump is included on-chip. if an external 14 v to 16 v supply is available, the two capacitors on cp1Ccp4 can be omit- ted, and this supply can be connected to cp5 (pin 7d) with a 100 nf decoupling capacitor in place of the 47 nf. after the demodulation stage, there is a single-pole low-pass filter consisting of an internal 9 k? resistor (r sen1 ) and an external user-supplied capacitor (cmid). a cmid capacitor of 100 nf sets a 400 hz 35% low-pass pole and is used to limit high frequency artifacts before final amplification. the band- width limit capacitor, c out , sets the pass bandwidth (see figure 23 and the setting bandwidth section). agnd temp st2 st1 cp1 cp2 rateout cp4 pdd cmid sumj 2.5v 6a 5a 4a 3a 2a 1b 1c 1d 1e 1f 7b 7c 7d 7e 7f 6g 5g 4g 3g 2g cp5 cp3 100nf c out = 22nf 22nf avcc 100nf 100nf pgnd 22nf 47nf 5v note that inner rows/columns of pins have been omitted for clarity but should be connected in the application. figure 22. example application circuit (top view) supply and common considerations only power supplies used for supplying analog circuits are rec- ommended for powering the adxrs150. high frequency noise and transients associated with digital circuit supplies may have adverse effects on device operation. figure 22 shows the recommended connections for the adxrs150 where both avcc and pdd have a separate decoupling capacitor. these should be placed as close to their respective pins as possible before routing to the system analog supply. this will minimize the noise injected by the charge pump that uses the pdd supply. it is also recommended to place the charge pump capacitors connected to the cp1Ccp4 pins as close to the part as possible. these capacitors are used to produce the on-chip high voltage supply switched at the dither frequency at approximately 14 khz. care should be taken to ensure that there is no more than 50 pf of stray capacitance between cp1Ccp4 and ground. surface-mount chip capacitors are suitable as long as they are rated for over 15 v. 5v + ? self test avcc st1 st2 3a 5g 4g adxrs150 cp2 cp1 pdd 4a 5a 7e 6g charge pump/reg. 12v ptat 7f 6a 7b 7c 7d 47nf cp4 cp3 cp5 rate sensor 2g 1f 1d coriolis signal channel agnd cmid 1c sumj rate- out 2.5v 1b 2a 1e 3g temp r out 180k ? 1% resonator loop demod 2.5v ref 9k ? 35% 100nf 22nf pgnd 100nf 100nf c out r sen1 r sen2 22nf 03226-b-023 figure 23. block diagram with external components setting bandwidth external capacitors cmid and c out are used in combination with on-chip resistors to create two low-pass filters to limit the bandwidth of the adxrs150s rate response. the C3 db frequency set by r out and c out is ( ) out out out c r / f = 2 1 and can be well controlled since r out has been trimmed during manufacturing to be 180 k? 1%. any external resistor applied between the rateout (1b,2a) and sumj (1c,2c) pins results in ( )( ) ext ext out r / r r + = k ? 180 k ? 180
adxrs150 rev. b | page 10 of 12 the C3 db frequency is set by rsen (the parallel combination of r sen1 and r sen2 ) at about 4.5 k? nominal; cmid is less well controlled since r sen1 and r sen2 have been used to trim the rate sensitivity during manufacturing and have a 35% tolerance. its primary purpose is to limit the high frequency demodulation artifacts from saturating the final amplifier stage. thus, this pole of nominally 400 hz @ 0.1 f need not be precise. lower frequency is preferable, but its variability usually requires it to be about 10 times greater (in order to preserve phase integrity) than the well-controlled output pole. in general, both C3 db filter frequencies should be set as low as possible to reduce the amplitude of these high frequency artifacts as well as to reduce the overall system noise. increasing measurement range the full-scale measurement range of the adxrs150 can be increased by placing an external resistor between the rateout (1b, 2a) and sumj (1c, 2c) pins, which would parallel the internal r out resistor that is factory-trimmed to 180 k?. for example, a 330 k? external resistor will give approximately 8.1 mv//sec sensitivity and a commensurate ~50% increase in the full-scale range. this is effective for up to a 4 increase in the full-scale range (minimum value of the paral- lel resistor allowed is 45 k?). beyond this amount of external sensitivity reduction, the internal circuitry headroom require- ments prevent further increase in the linear full-scale output range. the drawbacks of modifying the full-scale range are the additional output null drift (as much as 2/sec over tempera- ture) and the readjustment of the initial null bias (see the null adjustment section). temperature output and calibration it is common practice to temperature-calibrate gyros to improve their overall accuracy. the adxrs150 has a tempera- ture-proportional voltage output that provides input to such a calibration method. the voltage at temp (3f, 3g) is nominally 2.5 v at 27c and has a ptat (proportional to absolute tem- perature) characteristic of 8.4 mv/c. note that the temp output circuitry is limited to 50 a source current. using a 3-point calibration technique, it is possible to calibrate the adxrs150s null and sensitivity drift to an overall accuracy of nearly 300/hour. an overall accuracy of 70/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. using the adxrs150 with a supply-ratiometric adc the adxrs150s rateout signal is nonratiometric, i.e., nei- ther the null voltage nor the rate sensitivity is proportional to the supply. instead they are nominally constant for dc supply changes within the 4.75 v to 5.25 v operating range. if the adxrs150 is used with a supply-ratiometric adc, the adxrs150s 2.5 v output can be converted and used to make corrections in software for the supply variations. null adjustment null adjustment is possible by injecting a suitable current to sumj (1c, 2c). adding a suitable resistor to either ground or the positive supply is a simple way of achieving this. the nomi- nal 2.5 v null is for a symmetrical swing range at rateout (1b, 2a). however, a nonsymmetric output swing may be suit- able in some applications. note that if a resistor is connected to the positive supply, supply disturbances may reflect some null instability. digital supply noise should be avoided particularly in this case (see the supply and common considerations section). the resistor value to use is approximately ) v ? v )/( , . ( r null1 null0 null 000 180 5 2 = v null0 is the unadjusted zero-rate output, and v null1 is the target null value. if the initial value is below the desired value, the resistor should terminate on common or ground. if it is above the desired value, the resistor should terminate on the 5 v sup- ply. values typically are in the 1 m? to 5 m? range. if an external resistor is used across rateout and sumj, the parallel equivalent value is substituted into the above equation. note that the resistor value is an estimate since it assumes v cc = 5.0 v and v sumj = 2.5 v. self-test function the adxrs150 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 inputs st1 (5f, 5g), st2 (4f, 4g), or both. st1 causes the voltage at rateout to change about C0.66 v, and st2 causes an opposite change of +0.66 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. since st1 and st2 are not necessarily closely matched, actuat- ing both simultaneously may result in an apparent null bias shift. continuous self-test the one-chip integration of the adxrs150 gives it higher reli- ability than is obtainable with any other high volume manufac- turing method. also, 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. how- ever, some applications may warrant continuous self-test while sensing rate. application notes outlining continuous self-test techniques are also available on the analog devices website.
adxrs150 rev. b | page 11 of 12 acceleration sensitivity the sign convention used is that lateral acceleration is positive in the direction from pin column a to pin column g of the package. that is, a device has positive sensitivity if its voltage output increases when the row of pins 2aC6a are tipped under the row of pins 2gC6g in the earths gravity. there are two effects of concern, shifts in the static null and induced null noise. scale factor is not significantly affected until the acceleration reaches several hundred m/s 2 . vibration rectification for frequencies up to 20 khz is on the order of 0.00002(/s)/(m/s 2 ) 2 , is not significantly dependent on frequency, and has been verified up to 400 m/s 2 rms. linear vibration spectral density near the 14 khz sensor reso- nance translates into output noise. in order to have a significant effect, the vibration must be within the angular rate bandwidth (typically 40 hz of the resonance), so it takes considerable high frequency vibration to have any effect. away from the 14 khz resonance the effect is not discernible, except for vibration frequencies within the angular rate pass band. this can be seen in figure 10 to figure 15 for the various sensor axes. the in-band effect can be seen in figure 25. this is the result of the static g -sensitivity. the specimen used for figure 25 had a g -sensitivity of 0.15/s/ g and its total in-band noise degraded from 3 mv rms to 5 mv rms for the specified vibration. the effect of broadband vibration up to 20 khz is shown in figure 24 and figure 26. the output noise of the part falls away in accordance with the output low-pass filter and does not contain any spikes greater than 1% of the low frequency noise. a typical noise spectrum is shown in figure 27. time (sec) rateout (v) 2.50 2.52 2.54 2.56 0 24 6 8 10 2.58 2.60 figure 24. random vibration (lateral) 10 khz to 20 khz at 0.01 g/ hz with 60 hz sampling and 0.5 sec averaging time (sec) rateout (v) 2.50 2.52 2.54 2.56 0 24 6 8 10 2.58 2.60 figure 25. random vibration (lateral) 2 hz to 40 hz, 3.2 g rms time (sec) rateout (v) 2.50 2.52 2.54 2.56 0 24 6 8 10 2.58 2.60 static 0.8mv rms shaking 2.4mv rms figure 26. random vibration (lateral) 10 khz to 20 khz at 0.01 g/ hz with 60 hz sampling and 0.5 sec averaging frequency (hz) rateout (v) ?130 ?110 ?120 ?100 ?90 0 10 100 1000 10000 100000 ?80 ?70 ?60 figure 27. noise spectral density at rateout Cbw = 4 hz
adxrs150 rev. b | page 12 of 12 outline dimensions a b c d e f g b o t t o m view 76543 top view 3.65 max seating plane detail a ball diameter 7.00 bsc sq 4.80 bsc 0.60 0.55 0.50 3.20 2.50 0.44 0.25 0.15 max coplanarity 0.80 bsc 21 ball a1 indicator a1 corner index area detail a figure 28. 32-lead chip scale ball grid array [cspbga] (bc-32) dimensions shown in millimeters ordering guide model temperature range package description package outline adxrs150abg C40c to +85c 32-lead bga bc-32 adxrs150abg-reel C40c to +85c 32-lead bga bc-32 ADXRS150EB evaluation board ? 2004 analog devices, inc. all rights reserved. trademarks and regis- tered trademarks are the property of their respective owners. c03226C0C3/04(b)

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