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3-axis 200 g analog mems accelerometer preliminary technical data ADXL377 rev. prb 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 ?2012 analog devices, inc. all rights reserved. features 3-axis sensing 200 g measurement range analog output for full impact event visibility low power: 300 a (typical) selectable bandwidth up to 1600hz bandwidth (xy) up to 1200hz bandwidth (z) single-supply operation: 1.8 v to 3.6 v 10,000 g shock survival small, low profile package 3 mm 3 mm 1.45 mm lfcsp applications high impact detection for: concussive forces possible head trauma industrial machinery industrial tools warranty protection impact black boxes general description the ADXL377 is a small, thin, low power, complete 3-axis accelerometer with signal conditioned voltage outputs. the product measures acceleration with a minimum full-scale range of 200 g. the ADXL377 is designed to measure dynamic acceleration resulting from high impact events without sensor saturation. the analog output of the ADXL377 provides for full visibility of an impact event so potentially critical data is not lost. the user selects the bandwidth of the accelerometer using the c x , c y , and c z capacitors at the x out , y out , and z out pins. bandwidths can be selected to suit the application, with a range of 0.5 hz to 1600 hz for x and y axes and a range of 0.5 hz to 1200 hz for the z axis. this wide bandwidth allows the ADXL377 to detect shock and impact events on industrial applications that have a higher frequency component. the ADXL377 is available in a small, low profile, 3 mm 3 mm 1.45 mm, 16-lead, lead frame chip scale package (lfcsp_lq). functional block diagram figure 1. adxl337 3-axis sensor demodulator output amplifiers ac amplifier gnd st +3 v ~32k ? x out c x c y c z y out c dc v s z out ~32k ? ~32k ? 09358-001 ADXL377 free datasheet http:///
ADXL377 preliminary technical data rev. prb | page 2 of 13 table of contents features .............................................................................................. 1 ? applications ....................................................................................... 1 ? general description ......................................................................... 1 ? functional block diagram .............................................................. 1 ? specifications ..................................................................................... 3 ? absolute maximum ratings ............................................................ 4 ? esd caution .................................................................................. 4 ? pin configuration and function descriptions ............................. 5 ? typical performance characteristics ............................................. 6 ? theory of operation ........................................................................ 7 ? mechanical sensor ........................................................................ 7 ? performance ...................................................................................7 ? applications information .................................................................8 ? power supply decoupling ............................................................8 ? setting the bandwidth using c x , c y , and c z .............................8 ? self test ...........................................................................................8 ? design trade-offs for selecting filter characteristics: the noise/bw trade-off .....................................................................8 ? axes of acceleration sensitivity ..................................................9 ? layout and design recommendations ................................... 10 ? outline dimensions ....................................................................... 11 ?
preliminary technical data ADXL377 rev. prb | page 3 of 13 specifications t a = 25c, v s = 3 v, c x = c y = c z = 0.1 f, acceleration = 0 g , unless otherwise noted. all minimum and maximum specifications are guaranteed. typical specifications are not guaranteed. table 1. parameter test conditions/comments min typ max unit sensor input each axis measurement range 200 g nonlinearity % of full scale 0.3 % package alignment error 1 degrees interaxis alignment error 0.1 degrees cross-axis sensitivity 1 1 % sensitivity (ratiometric) 2 each axis sensitivity at x out , y out , z out v s = 3 v 5.8 6.5 7.2 mv/ g sensitivity change due to temperature 3 v s = 3 v 0.01 %/c 0 g bias level (ratiometric) 0 g voltage at x out , y out , z out v s = 3 v, 25 o c 1.4 1.5 1.6 v 0 g offset vs. temperature x out , y out 11 m g /c 0 g offset vs. temperature z out 15 m g /c noise performance noise density x out , y out 2.4 m g /hz rms noise density z out 3.6 m g /hz rms frequency response 4 bandwidth x out , y out 5 1 nf external filter 1600 hz bandwidth z out 5 1 nf external filter 1200 hz r filt tolerance 32 15% k sensor resonant frequency 16.5 khz self test 6 logic input low 0.6 v logic input high 2.4 v st actuation current 60 a output change at x out self test 0 to 1 - 6.5 mv output change at y out self test 0 to 1 6.5 mv output change at z out self test 0 to 1 11.5 mv output amplifier output swing low no load 0.1 v output swing high no load 2.8 v power supply operating voltage range 7 1.8 3.0 3.6 v supply current v s = 3 v 300 a turn-on time 8 1nf external filter 1 ms temperature operating temperature range ?40 +85 c 1 defined as coupling between any two axes. 2 sensitivity is essentially ratiometric to v s . 3 defined as the output change from ambient-to-maximum temperature or ambient-to-minimum temperature. 4 actual frequency response controlled by user-supplied external filter capacitors (c x , c y , c z ). 5 bandwidth with external capacitors = 1/(2 32 k c). for c x , c y = 0.003 f, bandwidth = 1.6 khz. for c z = 0.01 f, bandwidth = 500 hz. for c x , c y , c z = 10 f, bandwidth = 0.5 hz. 6 self test response changes cubically with v s . 7 tested at 3.0 v and guaranteed by design only (not tested) to work over the full range from 1.8 v to 3.6 v. 8 turn-on time is dependent on c x , c y , c z and is approximately 160 (c x or c y or c z ) + 1, where c x , c y , and c z are in f and the resulting turn-on time is in ms.
ADXL377 preliminary technical data rev. prb | page 4 of 13 absolute maximum ratings table 2. parameter rating acceleration (any axis, unpowered) 10,000 g acceleration (any axis, powered) 10,000 g v s ?0.3 v to +3.6 v all other pins (gnd ? 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. esd caution
preliminary technical data ADXL377 rev. prb | page 5 of 13 pin configuration and fu nction descriptions figure 2. pin configuration table 3. pin function descriptions pin no. mnemonic description 1, 3 res reserved. this pin must be connected to gnd or left open. 2 st self test. 4 y out y channel output. 5 x out x channel output. 6, 7 gnd must be connected to ground. 8 to 13 nc not internally connected. 14 v s supply voltage (3.0 v typical). 15 v s supply voltage (3.0 v typical). 16 z out z channel output. epad exposed pad. not internally connected but should be soldered for mechanical integrity. res 1 st 2 res 3 y out 4 nc 12 nc 11 nc 10 nc 9 x out gnd gnd nc 5678 16 z out 15 v s 14 v s 13 nc adxl337 top view (not to scale) +z +x +y 09358-003 notes 1. nc = no connect. 2 . exposed pad is not internally connected but should be soldered for mechanical integrity. a dxl377
ADXL377 preliminary technical data rev. prb | page 6 of 13 typical performance characteristics 0 0.2 0.4 0.6 0.8 1 1.2 10 100 1000 normalized ? magnitude frequency ? (hz) z ? axis x, ? y ? axes
preliminary technical data ADXL377 rev. prb | page 7 of 13 theory of operation the ADXL377 is a complete 3-axis acceleration measurement system. the ADXL377 has a measurement range of 200 g minimum. it contains a polysilicon surface micromachined sensor and signal conditioning circuitry to implement an open-loop acceleration measurement architecture. the output signals are analog voltages that are proportional to acceleration. the accelerometer can measure the static acceleration of gravity in tilt- sensing applications as well as dynamic acceleration resulting from motion, shock, or vibration. the accelerometer is designed to measure dynamic acceleration resulting from high impact events without output saturation. the sensor is a polysilicon surface micromachined structure built on top of a 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 moving mass and unbalances the differential capacitor resulting in a sensor output whose amplitude is proportional to acceleration. phase-sensitive demodulation techniques are then used to determine the magnitude and direction of the acceleration. the demodulator output is amplified and brought off chip through a 32 k resistor. the user then sets the signal bandwidth (bw) of the device by adding a capacitor. this filtering improves measurement resolution and helps prevent aliasing. mechanical sensor the ADXL377 uses a single structure for sensing the x, y, and z axes. as a result, the three axes sense directions are highly orthogonal with little cross-axis sensitivity. mechanical misalignment of the sensor die to the package is the chief source of cross-axis sensitivity. mechanical misalignment can be calibrated out at the system level. performance rather than using additional temperature compensation circuitry, innovative design techniques ensure that high performance is built into the ADXL377. as a result, there is neither quantization error nor nonmonotonic behavior, and temperature hysteresis is very low (typically less than 30 mg over the ?25c to +85c temperature range).
ADXL377 preliminary technical data rev. prb | page 8 of 13 applications information power supply decoupling for most applications, a single 0.1 f capacitor, c dc , placed close to the ADXL377 supply pins adequately decouples the accelerometer from noise on the power supply. however, in applications where noise is present at the 50 khz internal clock frequency (or any harmonic thereof), additional care in power supply bypassing is required because this noise can cause errors in acceleration measurement. if additional decoupling is needed, a 100 (or smaller) resistor or ferrite bead can be inserted in the supply line. additionally, a larger bulk bypass capacitor (1 f or greater) can be added in parallel to c dc . ensure that the connection from the ADXL377 ground to the power supply ground is low impedance because noise transmitted through ground has a similar effect as noise transmitted through v s . setting the bandwidth using c x , c y , and c z the ADXL377 has provisions for band limiting the x out , y out , and z out pins. capacitors must be added at these pins to implement low-pass filtering for antialiasing and noise reduction. the equation for the 3 db bandwidth is f ?3 db = 1/(2(32 k) c ( x , y, z ) ) or more simply f C3 db = 5 f/ c ( x , y, z ) the tolerance of the internal resistor (r filt ) typically varies as much as 15% of its nominal value (32 k), and the bandwidth varies accordingly. a minimum capacitance of 1000 pf for c x , c y , and c z is recommended in all cases. table 4. filter capacitor selection, c x , c y , and c z bandwidth (hz) capacitor (f) 50 0.10 100 0.05 200 0.025 500 0.01 1000 0.005 1600 0.003 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 accelerometer beam. the resulting movement of the beam allows the user to test if the accelerometer is functional. the typical change in output is ?1.08 g (corresponding to ?6.5 mv) in the x-axis, +1.08 g (or +6.5 mv) on the y-axis, and +1.83 g (or +11.5 mv) on the z-axis. this st pin can be left open circuit or connected to common (gnd) in normal use. never expose the st pin to voltages greater than v s + 0.3 v. if this cannot be guaranteed due to the system design (for instance, if there are multiple supply voltages), then 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 selected accelerometer bandwidth ultimately determines the measurement resolution (smallest detectable acceleration). filtering can be used to lower the noise floor to improve the resolution of the accelerometer. resolution is dependent on the analog filter bandwidth at x out , y out , and z out . the output of the ADXL377 has a typical bandwidth of greater than 500 hz. 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 decreased further to reduce noise and improve resolution. the ADXL377 noise has the characteristics of white gaussian noise, which contributes equally at all frequencies and is described in terms of g /hz (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 ADXL377 is determined by rms noise = noise density ) 1.6 ( ? bw it is often useful to know the peak value of the noise. peak-to-peak noise can only be estimated by statistical methods. table 5 is useful for estimating the probabilities of exceeding various peak values, given the rms value. table 5. estimation of peak-to-peak noise peak-to-peak value percent 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
preliminary technical data ADXL377 rev. prb | page 9 of 13 axes of acceleration sensitivity the axes of sensitivity for the accelerometer are shown in figure 3, and figure 4 shows the output response when the accelerometer is oriented parallel to each of these axes. figure 3. axes of acceleration sensit ivity, corresponding output voltage increases when accelerated along the sensitive axis figure 4. output response vs. orientation to gravity a z a y a x t o p 09358-030 x out = ?1 g y out = 0 g z out = 0 g gravity x out = 0 g y out = 1 g z out = 0 g x out = 0 g y out = ?1 g z out = 0 g x out = 1 g y out = 0 g z out = 0 g x out = 0 g y out = 0 g z out = 1 g x out = 0 g y out = 0 g z out = ?1 g top top top top t o p 09358-031
ADXL377 preliminary technical data rev. prb | page 10 of 13 layout and design recommendations the recommended soldering profile is shown in figure 5 followed by a description of the profile features in table 6. the recomm ended pcb layout or solder land drawing is shown in figure 6. figure 5. recommended soldering profile table 6. recommended soldering profile profile feature sn63/pb37 pb-free average ramp rate (t l to t p ) 3c/sec maximum 3c/sec maximum preheat minimum temperature (t smin ) 100c 150c maximum temperature (t smax ) 150c 200c time (t smin to t smax ), t s 60 sec to 120 sec 60 sec to 180 sec t smax to t l ramp-up rate 3c/sec maximum 3c/sec maximum time maintained above liquidous (t l ) liquidous temperature (t l ) 183c 217c time (t l ) 60 sec to 150 sec 60 sec to 150 sec peak temperature (t p ) 240c + 0c/?5c 260c + 0c/?5c time within 5c of actual peak temperature (t p ) 10 sec to 30 sec 20 sec to 40 sec ramp-down rate 6c/sec maximum 6c/sec maximum time 25c to peak temperature (t 25c ) 6 minutes maximum 8 minutes maximum figure 6. recommended pcb layout t p t l t 25c t s preheat critical zone t l to t p temperature time ramp-down ramp-up t smin t smax t p t l 09358-002 c enter pad is not internally connected but should be soldered for mechanical integrity 0.40 max 0.50 0.25 1.60 0.50 0.25 3 3 0.25 max 1.60 dimensions shown in millimeters 09358-004
preliminary technical data ADXL377 rev. prb | page 11 of 13 outline dimensions figure 7. 16-lead lead frame chip scale package [lfcsp_lq] 3 mm 3 mm body, thick quad (cp-16-28) dimensions shown in millimeters 3.10 3.00 sq 2.90 0.30 0.25 0.18 1.70 1.60 sq 1.50 1 0.50 bsc bottom view top view 16 5 8 9 12 13 4 exposed pad p i n 1 i n d i c a t o r 0.45 0.40 0.35 seating plane 0.05 max 0.02 nom 0.152 ref 0.20 min coplanarity 0.08 pin 1 indicator 1.50 1.45 1.40 for proper connection of the exposed pad, refer to the pin configuration and function descriptions section of this data sheet. 04-27-2010-a
ADXL377 preliminary technical data rev. prb | page 12 of 13 notes
preliminary technical data ADXL377 rev. prb | page 13 of 13 notes ?2012 analog devices, inc. all rights reserved. trademarks and registered trademarks are the prop erty of their respective owners. pr10765-0-5/12(prb)

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