a low cost 1.5g single/dual axis accelerometer preliminary technical data adxl103/203 features single/dual axis accelerometer on a single ic chip 5mm x 5mm x 2mm lcc package 1m g resolution at 60hz low pow er: < 700 a at v dd =5v high zero g bias stability and sensitivity accuracy x and y axes aligned to w i thin 0.1 (ty pical) bw adjustment w i th a single capacitor single supply operation 3500g shock survival applications vehicle dynamic control alarms and motion detectors high accuracy, 2 axis tilt sensing with faster response than electrolytic, mercury or thermal sensors navigation platform stabilization electronic chassis control general description the adxl103/ 203 are hi gh preci si on, l o w power, com p l e t e single and dual axis accelerom et ers with signal conditioned v o ltag e o u t p u t s, all o n a sin g l e m o n o lith ic ic. th e adxl103/203 will m easure acceleration with a full-scale range of 1.7 g (t y p i cal ). the adxl103/ 203 can m easure both dynam i c acceleration (e.g . vibration) and static acceleration (e.g. gravity). the outputs are analog voltage s proportional to acceleration (1v/ g). innovat i v e desi gn t echni ques are used t o ensure high zero g bias accuracy ( 2 5 m g typ i cal), an d stab ility (typ ically b e tter th an 0 . 1 m g / c), as well as tig h t sen s itiv ity accuracy ( 6 % ), an d stab ility (typ ically b e tter th an 50ppm/c). the t y pi cal noi se fl oor i s 150ug/ hz al l o wi ng si gnal s bel o w 1m g (0 .0 6 o f in clin atio n ) to b e reso lv ed in tilt sen s in g appl i cat i ons usi ng narrow bandwi d t h s (<10hz). the user selects the bandwidth of the accelerom eter using capacitors cx and cy at the x out and y out pi ns. ban d w id th s o f 1 h z to 2 khz m a y b e selected to su it th e appl i cat i on. the adxl103/ 203 are avai l a bl e i n 5m m x 5m m x 2m m 8 pad herm etic lcc package. x s e ns o r d e m od y s ensor a dx l 2 0 3 e vdd com de m o d o s c i l l at or x ou t y ou t 32k 32k s e l f t est r f ilt rf i l t cx cy + 5 v c dc x s e ns or d e m od a d x l 10 3e vd d com o s c illa t o r x ou t 32 k s e lf t e s t rf i l t cx +5. v c dc information furnished by analog devices is believed to be accurate and reliable. how e ver 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. spec ifications subject to change w i thout notice. no license is granted by implication or otherw i se under any patent or patent rights of analog devices. trademarks and registered trademarks are the property of their respective companies rev. pra. 3/28/2003 one technology way , p.o. box 9106, norw ood, ma 02062- 9106, u.s.a. tel: 781.329.4700 www. anal og.c o m fax: 781.326.8703 ? 2003 analog devices inc. all rights res e rv ed
preliminary technical data adxl103/203 r e v. pra 3/ 28/ 2003 2 of 6 absolute max i mum ratings* acceleration (any axis, unpowered for 0.5m s) 3500g acceleration (any axis, powered for 0.5m s) 3500g drop t e st (concret e ) 1.2m +vs -0.3v to +6.0v out put short c i rcui t durat i on, (any pi n t o com m on)indefi ni t e operating tem p erature -55 package characteri sti c s p a c k a g e t h e t a j a t h e t a j c d e v i ce wei g h t 8 pi n lc c t bd c / w t bd c / w <1.0 gram s ordering guid e m o d e l # axes specifie d vol t age temperature range adxl103be-reel 1 + 5 v -40 adxl103e vdd adx l203 p i n descrip t io n p i n n a m e d e s c r i p t i o n 1 s t s e l f t e s t 2 dnc do not connect 3 c o m c o m m o n 4 dnc do not connect 5 dnc do not connect 6 y out y channel out put 7 x out x channel out put 8 v d d + 5 v st dnc com xout dnc dnc 8 7 1 6 2 5 3 4 dnc bottom view adxl203e vdd st dnc com xout yout dnc 8 7 1 6 2 5 3 4 dnc bottom view
preliminary technical data adxl103/203 r e v. pra 3/ 28/ 2003 3 of 6 a d xl103/ 203- spec i f i c a t i o ns a d x l 1 03/ 20 3b e para m e te r c o n ditio n s m i n t y p m a x u n its s e n s o r e a ch ax is ful l sc a l e r a nge 1 1. 5 1 . 7 g n o n lin ea rity 2 0 . 5 2. 5 % pa ck a g e a l i g nm ent er r o r 1 d egr e e a l i g n m en t e r r o r ( a d x l 2 03) x s e n s or t o y sen s or 0. 1 d eg rees c r o s s a x is s e n s itiv ity 2 5 % s e n s it iv i t y (ra tio m e tric ) 3 e a ch ax is s e n s i t i v i t y v s = + 5 . 0 v 9 40 1000 106 0 m v / g s e n s i tiv ity d r if t o v e r te m p e r a t u r e v s = + 5 .0 v 0.3 % z e r o g b i a s l e v e l (ra tio m e tric) e a c h ax is in itial z e ro g o u tp u t d e v i atio n f r o m id ea l @ 2 5 c , v s = + 5 .0v 2 5 m g z e r o g d r i f t ove r t e m p e r a t ur e 0 . 1 m g/ c ze r o g vo l t a g e v s = + 5 . 0 v 2 . 4 0 2 . 5 2 . 6 0 v no i s e p e rfo r m a nc e o u t p u t no i s e < 4 k hz , vs = + 5 . 0 v, @ 2 5 c 6 m v rms n o i s e d e n s i t y @ 25 c 150 u g / r oot h z r m s fr eq uen c y r e sp on se 4 se ns o r r e s o na n t fr e q u e nc y @ 2 5 c, v s = + 5 . 0 v 5 . 5 kh z cx, cy ra nge 5 0. 002 4. 7 u f r f ilt to le ran c e 3 2k o h m n o m i n a l 2 2 3 2 4 2 k ? ? ?
preliminary technical data adxl103/203 theory of operation the adxl103/203 are com p lete, acceleration m easurem e nt sy stem s on a single m onolithic ic. the adxl103 is a single axis accelerom eter, while the adxl203 is a dual axis accelerom eter. they contain a poly s ilicon surface-m i crom achined sensor and signal conditioning circuitry to im plem ent an open loop acceleration m easurem e nt architecture. the output signals are analog voltage proportional to acceleration. the adxl103/203 is c a p a b l e o f m easuring both positive and negative accelerations to a t least 1.5 g . the accelerom eter can m easure static acceleration forces such as gravity , allowing it to be used as a tilt s e n s o r . the sensor is a surface m i crom achined poly s ilicon structure built on top of the silicon wafer. poly silicon springs suspend t h e s t r u c t u r e over the surface of the wafer and provide a resistance against acceleration forces. deflection of the structure is m eas u r e d u s i n g a differential capacitor that consists of independent fixed plates and central plates attached to the m oving m ass. the fixed p l a t e s a r e d r i v e n b y 180 out of phase square waves. accele r a tion will deflect the beam and unbalance the d i f f e r e n t i a l capacitor, resulting in an output square wave whose am plitude is proportional t o acceleration. phase sensitive dem odulation techniques are t h e n u s e d t o r e c t i f y the signal and determ ine the direction of the a c celeration. the output of the dem odulator is am plified and brought off-chip through a 32k ? performance rather than using additional tem p erature com p ensation circuitry , innovative design techniques have been used to ensure high perform ance is built in. as a result there is essentially no quantization errors or non-m onotonic behavior, and tem p erature hy steresis is very low (ty p ically less than 10m g over the ?40 to +125c tem p erature range). figure 1 shows the zero g output perform ance of eight parts (x and y axis) over a ?40 to +125c tem p erature range. figure 2 dem onstrates the ty pical sensitivity shift over tem p erature for supply voltages of 2.5v to 6v. sensitivity stability is optim ized for vdd=5v, but is still very good over the specified range. figure 1. z ero g output drift over temperature figure 2. sensitivity shift over temperature applications power supply decoupling for m o st applications a single 0.1 f capacitor, c dc , will a d equately decouple the accelerom eter from noise on t h e p o w e r supply . howe ver, in som e cases, particularly where noise is present at the 140khz internal clock frequency ( o r a n y h a r m o n i c t h e r e o f ) , noise on the supply m a y cause interference on the adxl103/203 output. i f a d d i t i o n a l decoupling is needed, a 100 ? setting the bandwidth using c x and c y the adxl103/203 has provisions for band-lim iting the x out and y out pins. capacitors m u st be added at these p i n s t o i m p l e m e n t low-pass filtering for anti-aliasing and noise reduction. the equation for the 3 db bandwidth is: r e v. pra 3/ 28/ 2003 4 of 6
preliminary technical data adxl103/203 rev. pra 3/28/2003 5 of 6 f -3db = 1/(2 (32k )* c (x,y) ) or, more simply, f -3db = 5uf/c (x,y) the tolerance of the internal resistor (r filt ) can vary typically as much as 15% of its nominal value of 32 k ? ; so the bandwidth will vary accordingly. a minimum capacitance of 1000 pf for c (x, y) is required in all cases. table i. filter capacitor selection, c x and c y capacitor bandwidth 10 hz 0.47 f 50 hz 0.10 f 100 hz 0.05 f 200 hz 0.027 f 500 hz 0.01 f 5 khz 0.001 f self test the st pin controls the self-test feature. when this pin is set to v dd , an electrostatic force is exerted on the beam of the accelerometer. the resulting movement of the beam allows the user to test if the accelerometer is functional. the typical change in output will be 800m g (corresponding to 800mv). this pin may be left open circuit or connected to common in normal use. design trade-offs for selecting filter characteristics: the noise/bw trade-off the accelerometer bandwidth selected will ultimately determine the measurement resolution (smallest detectable acceleration). filtering can be used to lower the noise floor, which improves the resolution of the accelerometer. resolution is dependent on the analog filter bandwidth at x out and y out . the output of the adxl103/203 has a typical bandwidth of 2 khz. the user must filter the signal at this point to limit aliasing errors. the analog bandwidth must be no more than half the a/d sampling frequency to minimize aliasing. the analog bandwidth may be further decreased to reduce noise and improve resolution. the adxl103/203 noise has the characteri s t i c s o f w h i t e gaussian noise that contributes equally at all frequencies and is described in terms of g per root hz; i.e., the noise is proportional to the square root of the bandwidth of the accelerometer. it is recommended that the user 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 t y p i c a l n o i s e o f the adxl103/203 is determined by the following equation: rms noise = (150ug/ hz) * ( bw * 1.6) for example, at 100 hz the noise will be: noise = (150ug/ hz) * ( 100 * 1.6) = 1.9mg rms often the peak value of the noise is desired. peak-to- peak noise can only be estimated by statistical methods. table ii is useful for estimating the probabilities of exceeding various peak values, given the rms value. the peak-to-peak noise value will give the best estimate of the uncertainty in a single measurement. table iii gives typical noise output of the adxl103/203 for various c x and c y values. table ii. estimation of peak-to-peak noise peak-to-peak value % of time that noise will exceed nominal peak-to-peak value 2 x rms 32% 4 x rms 4.6% 6 x rms 0.27% 8 x rms 0.006% . table iii. filter capacitor selection (c x , c y) bandwidth cx, cy rms noise peak-to-peak noise estimate 10hz 0.47uf 0.6mg 3.6mg 50hz 0.1uf 1.3mg 8mg 100hz 0.047uf 1.9mg 11.4mg 500hz 0.01uf 4.2mg 25mg using the adxl103/203 with operating voltages other than 5v
preliminary technical data adxl103/203 rev. pra 3/28/2003 6 of 6 the adxl103/203 is tested and specified at vdd=5v, however it can powered with vdd as low as 3v or as high as 5.25v. some performance parameters will change as the supply voltage is varied. the adxl103/203 output is ratiometric, so the output sensitivity (or scale factor) will vary proportionally to supply voltage. at vdd=3v the output sensitivity is typically 560mv/g. the zero g bias output is also ratiometric, so the zero g output is nominally equal to vdd/2 at all supply voltages. the output noise is not ratiometric, but absolute in volts. therefore the noise density increases as the supply voltage decreases. this is because the scale factor (mv/g) decreases while the noise voltage remains constant. self-test response in g is roughly proportional to the square of the supply voltage. at vdd=3v the self-test response will be approximate ly equivalent to 300mg (typical). supply current decreases as the supply voltage decreases. typical current consumption at vdd=3v is 500ua. using the adxl203 as a dual-axis tilt sensor one of the most popular applications of the adxl203 is tilt measurement. an accelerometer uses the force of gravity as an input vector to determine orientation of an object in space. an accelerometer is most sensitive to tilt when its sensitive axis is perpendicular to the force of gravity, i.e. parallel to the earth?s surface. at this orientation its sensitivity to changes in tilt is highest. when the accelerometer is oriented on axis to gravity, i.e., near its +1 g or ?1 g reading, the change in output acceleration per degree of tilt is negligible. when the accelerometer is perpend i c u l a r to gravity, its output will change nearly 17.5 m g per degree of tilt, but at 45 degrees it is changing only at 12.2 m g per degree, and resolution declines. a dual axis tilt sensor: converting acceleration to tilt when the accelerometer is oriented so both its x and y axes are parallel to the earth?s surface it can be used as a two axis tilt sensor w i t h a r o l l a n d a p i t c h a x i s . o n c e the output signal from the accelerometer has been converted to an acceleration that varies between ?1 g and +1 g, the output tilt in degrees is calculated as follows: pitch = asin (ax /1 g ) roll = asin (ay /1 g ) be sure to account for overranges. it is possible for the accelerometers to output a signal greater than 1 g due to vibration, shock or other accelerations.
adi home adxl203 description data sheets selection tables technical library press releases design tools packages package/price information order samples purchase all design resources package/price info for detailed packaging information, please select the data sheets button. * the pricing listed here is provided only for budgetary purposes as recommended list price in u.s. dollars in the united states ex factor per unit for the stated volume. to obtain detailed price and availability information for analog devices products, please visit the price and availability section. pricing displayed for evaluation boards and kits is based on 1-piece pricing. model status package description pin count temperature range price* (100-499) adxl203ce production lcc:cer leadless chip carr 8 industrial $15.00 adxl203ce-reel production lcc:cer leadless chip carr 8 industrial - pricing is not available for pre-release parts, please contact your local sales office or authorized distributor for additional information. privacy | about this site | contact adi | site map | registration ? 1995-2004 analog devices, inc. all rights reserved.
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