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precision 18 g single-/dual-axis i mems accelerometer adw22035/adw22037 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 ?2008 analog devices, inc. all rights reserved. features high performance, single-/dual-axis accelerometer on a single ic chip low power: 740 a at v s = 5 v (typical) high zero g bias stability high sensitivity accuracy C40c to +125c temperature range x and y axes aligned to within 0.1 (typical) bw adjustment with a single capacitor single-supply operation 3500 g shock survival rohs-compliant compatible with sn/pb- and pb-free solder processes 5 mm 5 mm 2 mm lcc package applications vibration monitoring and compensation abuse event detection sports equipment vehicle dynamic control general description the adw22035/adw22037 are high precision, low power, complete single- and dual-axis i mems? accelerometers with signal conditioned voltage outputs, all on a single, monolithic ic. the adw22035/adw22037 measure acceleration with a full-scale range of 18 g . the adw22035/adw22037 can measure both dynamic acceleration, such as vibration, and static acceleration, such as gravity. the user selects the bandwidth of the accelerometer using capacitor c x and capacitor c y at the x out and y out pins. bandwidths of 0.5 hz to 2.5 khz can be selected to suit the application. the adw22035/adw22037 are available in 5 mm 5 mm 2 mm, 8-terminal hermetic lcc packages. functional block diagrams adw22035 sensor 5 v output amp com st x out v s c dc c x r filt 32k ? demod ac amp 07755-001 figure 1. adw22037 sensor 5 v output amp output amp com st y out v s c dc c y r filt 32k ? demod x out c x r filt 32k? ac amp 07755-101 figure 2.
adw22035/adw22037 rev. 0 | page 2 of 12 table of contents features .............................................................................................. 1 ? applications ....................................................................................... 1 ? general description ......................................................................... 1 ? functional block diagrams ............................................................. 1 ? revision history ............................................................................... 2 ? specifications ..................................................................................... 3 ? absolute maximum ratings ............................................................ 4 ? thermal resistance ...................................................................... 4 ? esd caution .................................................................................. 4 ? pin configurations and function descriptions ........................... 5 ? typical performance characteristics ............................................. 6 ? theory of operation ........................................................................ 8 ? performance ...................................................................................8 ? applications information .................................................................9 ? power supply decoupling ............................................................9 ? setting the bandwidth using c x and c y ....................................9 ? self test ...........................................................................................9 ? design trade-offs for selecting filter characteristics: the noise/bw trade-off .....................................................................9 ? using the adw22035/adw22037 with operating voltages other than 5 v ............................................................................ 10 ? outline dimensions ....................................................................... 11 ? ordering guide .......................................................................... 11 ? revision history 10/08revision 0: initial version
adw22035/adw22037 rev. 0 | page 3 of 12 specifications t a = ?40c to +125c, v s = 5 v, c x = c y = 0.1 f, acceleration = 0 g , unless otherwise noted. table 1. parameter conditions min 1 typ max 1 unit sensor input each axis measurement range 2 18 g nonlinearity % of full scale 0.2 1.25 % package alignment error 1 degrees alignment error (adw22037) x sensor to y sensor 0.1 degrees cross-axis sensitivity 1.5 3 % sensitivity (ratiometric) 3 each axis sensitivity at x out , y out v s = 5 v 94 100 106 mv/g sensitivity change due to temperature 4 v s = 5 v 0.3 % zero g bias level (ratiometric) each axis 0 g voltage at x out , y out v s = 5 v 2.4 2.5 2.6 v initial 0 g output deviation from ideal v s = 5 v, 25c 125 mg 0 g offset vs. temperature 1 m g /c noise performance output noise <4 khz, v s = 5 v 2 mv rms noise density 130 g /hz rms frequency response 5 c x , c y range 6 0.002 10 f r filt tolerance 24 32 40 k sensor resonant frequency 5.5 khz self-test (st) 7 logic input low 1 v logic input high 4 v st input resistance to ground 30 50 k output change at x out , y out self-test 0 to self-test 1 60 80 100 mv output amplifier output swing low no load 0.05 0.2 v output swing high no load 4.5 4.8 v power supply operating voltage range 3 6 v quiescent supply current 0.7 1.1 ma turn-on time 8 20 ms 1 all minimum and maximum specifications are guaranteed. typical specifications are not guaranteed. 2 guaranteed by measurement of initial offset and sensitivity. 3 sensitivity is essentially ratiometric to v s . for v s = 4.75 v to 5.25 v, se nsitivity is 18.6 mv/v/ g to 21.5 mv/v/ g . 4 defined as the output change from ambient-to-maximum temperature or ambient-to-minimum temperature. 5 actual frequency response controlled by user-supplied external capacitor (c x , c y ). 6 bandwidth = 1/(2 32 k c). for c x , c y = 0.002 f, bandwidth = 2500 hz. for c x , c y = 10 f, bandwidth = 0.5 hz. minimum/maximum values are not tested. 7 self-test response changes cubically with v s . 8 larger values of c x , c y increase turn-on time. turn-o n time is approximately 160 c x or c y + 4 ms, where c x , c y are in f.
adw22035/adw22037 rev. 0 | page 4 of 12 absolute maximum ratings table 2. parameter rating acceleration (any axis, unpowered) 3500 g acceleration (any axis, powered) 3500 g drop test (concrete surface) 1.2 m v s ?0.3 v to +7.0 v all other pins (com ? 0.3 v) to (v s + 0.3 v) output short-circuit duration (any pin to common) indefinite temperature range (powered) ?55c to +125c temperature range (storage) ?65c to +150c stresses above those listed under 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. thermal resistance ja is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. table 3. thermal resistance package type ja jc device weight 8-terminal ceramic lcc 120c/w 20c/w <1.0 gram esd caution t p t l t 25c to peak t s preheat critical zone t l to t p temperature time ramp-down ramp-up profile feature sn63/pb37 average ramp rate (t l to t p ) 3c/sec max 3c/sec max 3c/sec max 3c/sec max preheat minimum temperature (t smin ) maximum temperature (t smax ) time (t smin to t smax )( t s ) 100c 150c 60 to 120 s 150c 200c 60 to 150 s t smin to t l ramp-up rate condition pb-free t smin t smax t p t l 07755-002 183c 60 to 150 s 217c 60 to 150 s time maintained above liquidous (t l ) liquidoustemperature (t l ) time ( t l ) peak temperature (t p ) 240c + 0c/?5c 260c + 0c/?5c time within 5c of actual peak temperature ( t p ) 10s to 30 s 20s to 40 s ramp-down rate time 25c to peak temperature 6c/sec max 6 minutes max 6c/sec max 8 minutes max figure 3. recommended soldering profile
adw22035/adw22037 rev. 0 | page 5 of 12 pin configurations and function descriptions 7 6 5 4 8 3 2 1 st dnc c om v s dnc +x adw22035 top view (not to scale) dnc = do not connect x out dnc dnc 07755-003 figure 4. adw22035 pin configuration table 4. adw22035 pin function descriptions pin no. mnemonic description 1 st self test 2 dnc do not connect 3 com common 4 dnc do not connect 5 dnc do not connect 6 dnc do not connect 7 x out x channel output 8 v s 3 v to 6 v 7 6 5 4 8 3 2 1 st dnc com v s dnc +x +y dnc = do not connect x out y out dnc 07755-004 adw22037 top view (not to scale) figure 5. adw22037 pin configuration table 5. adw22037 pin function descriptions pin no. mnemonic description 1 st self test 2 dnc do not connect 3 com common 4 dnc do not connect 5 dnc do not connect 6 y out y channel output 7 x out x channel output 8 v s 3 v to 6 v
adw22035/adw22037 rev. 0 | page 6 of 12 typical performance characteristics v s = 5 v for all graphs, unless otherwise noted. 0 10 20 30 40 50 60 ?50 ?40 ?30 ?20 ?10 0 10 20 30 40 50 percent of population (mv) 07755-005 figure 6. x-axis zero g bias deviation from ideal at 25c 0 5 10 15 20 25 30 35 ?3.0 ?2.5 ?2.0 ?1.5 ?1.0 ?0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 percent of population (m g /c) 07755-006 figure 7. x-axis zero g bias tempco 0 5 10 15 20 25 97 98 99 100 101 102 103 percent of population (mv/ g) 07755-007 figure 8. x-axis sensitivity at 25c 0 10 20 30 40 50 60 ?50 ?40 ?30 ?20 ?10 0 10 20 30 40 50 percent of population (mv) 07755-008 figure 9. y-axis zero g bias deviation from ideal at 25c 0 5 10 15 20 25 30 35 ?3.0 ?2.5 ?2.0 ?1.5 ?1.0 ?0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 percent of population (m g /c) 07755-009 figure 10. y-axis zero g bias tempco 0 5 10 15 20 25 97 98 99 100 101 102 103 percent of population (mv/ g) 07755-010 figure 11. y-axis sensitivity at 25c
adw22035/adw22037 rev. 0 | page 7 of 12 0 5 10 15 20 25 30 35 40 0.060 0.065 0.070 0.075 0.080 0.085 0.090 0.095 0.100 percent of population (v) 07755-011 figure 12. x-axis self-test response at 25c 97.5 98.0 98.5 99.0 99.5 100.0 100.5 101.0 ?50 ?25 0 25 50 75 100 125 sensitivity (mv) temperature (c) 07755-012 figure 13. sensitivity vs. temperature; parts soldered to pcb 0 10 20 30 40 50 60 70 80 90 680 700 720 740 760 780 800 820 840 860 880 900 920 940 960 percent of population (a) 25c 105c 07755-013 figure 14. supply current vs. temperature 0 5 10 15 20 25 30 35 40 45 0.060 0.065 0.070 0.075 0.080 0.085 0.090 0.095 0.100 percent of population (v) 07755-014 figure 15. y-axis self-test response at 25c 07755-015 time (2ms/div) vol t age (v) figure 16. turn-on time: c x , c y = 0.1 f, time scale = 2 ms/div
adw22035/adw22037 rev. 0 | page 8 of 12 theory of operation the adw22035/adw22037 is a complete acceleration measurement system on a single, monolithic ic. the adw22035/adw22037 is a dual-axis accelerometer. this device contains a polysilicon surface-micromachined sensor and signal conditioning circuitry to implement an open-loop acceleration measurement architecture. the output signals are analog voltages proportional to acceleration. the adw22035/ adw22037 are capable of measuring both positive and negative accelerations to at least 18 g . the sensor is a surface-micromachined polysilicon structure built on top of the silicon wafer. polysilicon springs suspend the structure over the surface of the wafer and provide a resistance against acceleration forces. deflection of the structure is measured using a differential capacitor that consists of independent fixed plates and plates attached to the moving mass. the fixed plates are driven by 180 out-of-phase square waves. acceleration deflects the beam and unbalances the differential capacitor, resulting in an output square wave whose amplitude is proportional to acce- leration. phase-sensitive demodulation techniques are then used to rectify the signal and determine the direction of the acceleration. the output of the demodulator is amplified and brought off-chip through a 32 k resistor. at this point, the user can set the signal bandwidth of the device by adding a capacitor. this filtering improves measurement resolution and helps prevent aliasing. performance rather than using additional temperature compensation circuitry, innovative design techniques ensure that high performance is built in to these devices. as a result, there is essentially no quantization error or nonmonotonic behavior, and temperature hysteresis is very low (typically less than 15 m g over the ?40c to +125c temperature range). figure 17 demonstrates the typical sensitivity shift over temper- ature for v s = 5 v. sensitivity stability is optimized for v s = 5 v, but is still very good over the specified range; it is typically better than 1% over temperature at v s = 3 v. earth's surface top view (not to scale) pin 8 x out = 2.5v y out = 2.4v x out = 2.5v y out = 2.5v pin 8 x out = 2.5v y out = 2.6v pin 8 x out = 2.4v y out = 2.5v pin 8 x out = 2.6v y out = 2.5v 07755-021 figure 17. output resp onse vs. orientation
adw22035/adw22037 rev. 0 | page 9 of 12 applications information power supply decoupling for most applications, a single 0.1 f capacitor, c dc , adequately decouples the accelerometer from noise on the power supply. however in some cases, particularly where noise is present at the 140 khz internal clock frequency (or any harmonic thereof), noise on the supply can cause interference on the adw22037 output. if additional decoupling is needed, a 100 (or smaller) resistor or ferrite beads can be inserted in the supply line of the adw22035/adw22037. additionally, a larger bulk bypass capacitor (in the 1 f to 22 f range) can be added in parallel to c dc . setting the bandwidth using c x and c y the adw22035/adw22037 have provisions for band limiting the x out and y out pins. capacitors must be added at these pins to implement low-pass filtering for antialiasing and noise reduc- tion. the equation for the 3 db bandwidth is f C3 db = 1/(2(32 k) c ( x , y ) ) or more simply, f C3 db = 5 f/ c ( x , y ) the tolerance of the internal resistor (r filt ) can vary typically as much as 25% of its nominal value (32 k); thus, the bandwidth varies accordingly. a minimum capacitance of 2000 pf for c x and c y is required in all cases. table 6. filter capacitor selection, c x and c y bandwidth (hz) capacitor (f) 1 4.7 10 0.47 50 0.10 100 0.05 200 0.027 500 0.01 self test the st pin controls the self-test feature. when this pin is set to v s , an electrostatic force is exerted on the beam of the accele- rometer. the resulting movement of the beam allows the user to test if the accelerometer is functional. the typical change in output is 800 m g (corresponding to 80 mv). this pin can be left open-circuit or connected to common in normal use. the st pin should never be exposed to voltage greater than v s + 0.3 v. if the system design is such that this condition cannot be guaranteed (that is, multiple supply voltages are present), a low v f clamping diode between st and v s is recommended. design trade-offs for selecting filter characteristics: the noise/bw trade-off the accelerometer bandwidth selected ultimately determines the measurement resolution (smallest detectable acceleration). filtering can be used to lower the noise floor, improving the resolution of the accelerometer. resolution is dependent on the analog filter bandwidth at x out and y out . the output of the adw22035/adw22037 has a typical band- width of 2.5 khz. the user must filter the signal at this point to limit aliasing errors. the analog bandwidth must be no more than half the analog-to-digital sampling frequency to minimize aliasing. the analog bandwidth can be further decreased to reduce noise and improve resolution. the adw22035/adw22037 noise has the characteristics of white gaussian noise, which contributes equally at all fre- quencies and is described in terms of g /hz (that is, the noise is proportional to the square root of the accelerometer bandwidth). the user should limit bandwidth to the lowest frequency needed by the application to maximize the resolution and dynamic range of the accelerometer. with the single pole roll-off characteristic, the typical noise of the adw22035/adw22037is determined by )6.1bw()hz/130( rmsnoise = g at 100 hz, the noise is g g m64.1)6.1100()hz/130( rmsnoise = = often, the peak value of the noise is desired. peak-to-peak noise can only be estimated by statistical methods. table 7 is useful for estimating the probabilities of exceeding various peak values, given the rms value. table 7. estimation of peak-to-peak noise peak-to-peak value % of time that noise exceeds nominal peak-to-peak value 2 rms 32 4 rms 4.6 6 rms 0.27 8 rms 0.006
adw22035/adw22037 rev. 0 | page 10 of 12 peak-to-peak noise values provide the best estimate of the uncertainty in a single measurement. peak-to-peak noise is estimated by 6 rms. table 8 gives the typical noise output of the adw22035/adw22037 for various c x and c y values. table 8. filter capacitor selection (c x , c y ) bandwidth (hz) c x , c y (f) rms noise (m g ) peak-to-peak noise estimate (m g ) 10 0.47 0.5 3.0 50 0.1 1.2 7.2 100 0.047 1.6 9.6 500 0.01 3.7 22.2 using the adw22035/adw22037 with operating voltages other than 5 v the adw22035/adw22037 are tested and specified at v s = 5 v; however, it can be powered with v s as low as 3 v or as high as 6 v. some performance parameters change as the supply voltage is varied. the adw22035/adw22037 output is ratiometric, thus the output sensitivity (or scale factor) varies proportionally to the supply voltage. at v s = 3 v the output sensitivity is typically 56 mv/ g . the zero g bias output is also ratiometric, thus the zero g output is nominally equal to v s /2 at all supply voltages. the output noise is not ratiometric but is absolute in volts; therefore, the noise density decreases as the supply voltage increases. this is because the scale factor (mv/ g ) increases while the noise voltage remains constant. at v s = 3 v, the noise density is typically 240 g /hz. self-test response in g is roughly proportional to the square of the supply voltage. however, when ratiometricity of sensitivity is factored in with supply voltage, self-test response in volts is roughly proportional to the cube of the supply voltage. thus, at v s = 3 v, the self-test response is approximately equivalent to 15 mv or equivalent to 270 m g (typical).
adw22035/adw22037 rev. 0 | page 11 of 12 outline dimensions 091307-b bottom view 1 3 5 7 top view 0.075 ref r 0.008 (4 plcs) 0.203 0.197 sq 0.193 0.20 0.15 0.10 (r 4 plcs ) 0.180 0.177 sq 0.174 0.087 0.078 0.069 0.008 0.006 0.004 0.077 0.070 0.063 0.054 0.050 0.046 0.030 0.025 0.020 0.028 0.020 dia 0.012 0.106 0.100 0.094 r 0.008 (8 plcs) figure 18. 8-terminal cerami c leadless chip carrier [lcc] (e-8-1) dimensions shown in inches ordering guide model number of axes specified voltage (v) temperature range package description package option ADW22035Z 1 1 5 C40c to +125c 8-terminal ceramic leadless chip carrier [lcc] e-8-1 ADW22035Z-rl 1 1 5 C40c to +125c 8-terminal ceramic leadless chip carrier [lcc] e-8-1 ADW22035Z-rl7 1 1 5 C40c to +125c 8-terminal ceramic leadless chip carrier [lcc) e-8-1 adw22037z 1 2 5 C40c to +125c 8-terminal ceramic leadless chip carrier [lcc] e-8-1 adw22037z-rl 1 2 5 C40c to +125c 8-terminal ceramic leadless chip carrier [lcc] e-8-1 adw22037z-rl7 1 2 5 C40c to +125c 8-terminal ceramic leadless chip carrier [lcc] e-8-1 1 z = rohs compliant part.
adw22035/adw22037 rev. 0 | page 12 of 12 notes ?2008 analog devices, inc. all rights reserved. trademarks and registered trademarks are the prop erty of their respective owners. d07755-0-10/08(0)

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