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75/s single chip yaw rate gyro with signal conditioning adxrs401 rev. 0 in fo rmation furn ished by an alog d e v i c e s is believed to be accurate and reliable. how e ver, n o resp on sibili ty is assume d b y a n alog de vices fo r its use, nor for an y i n fri n geme nt s of p a t e nt s or ot h e r ri ght s o f th ird parties th at may result fro m its use . s p ecificatio n s subj ec t to ch an g e witho u t n o tice. no licen s e is g r an te d by implicati o n or ot herwi s e u n der a n y p a t e nt or p a t e nt ri ghts of analog de v i ces. trademarks an d registered tra d ema r ks are the prop erty o f their respective ow ners. one technolog y way, p.o . box 9106, norwood, ma 02062-9106, u.s.a. t e l: 781. 329. 4 700 www.analog.com fax: 781. 326. 87 03 ? 2004 analog de vices, i n c. al l r i ght s r e ser v ed . features com p lete rate gyroscope on a single chip z-axis (yaw-r ate) response high vibratio n rejection o v er wi de frequency 20 00 g power e d shock survivab ility self-test on digital co mma nd temperature sensor output precision volt age reference output absolute rate output for precision app l ic ations 5 v si ngle -supply operatio n ultra small a n d l i ght (< 0.15 cc, < 0.5 gram) applic ati o ns gps nav i gation system s ima g e stabilization inertial meas urement unit s platform stabilization general description the ad xrs401 is a f u n c tio n al l y co m p let e and lo w cos t a n gu lar ra t e s e n s o r (g yr os co p e ), in teg r a t ed wi th al l o f th e r e q u ir ed e l e c t r o n ics o n on e ch i p . i t is man u fac t ur e d using ana l og d e vices sur f ace-micr o m achi ni n g t e chn i q u e, t h e s a m e hig h vol u me bi mos p r o c ess u s e d fo r hig h r e l i ab i l ity a u tomo t i ve ai r b ag a c c e l e rome te rs . i t i s a v ai l a bl e i n a 7 m m 7 m m 3 m m bg a s u r f a c e - m o u n t p a c k a g e . t h e output s i g n a l , r a t e ou t ( 1 b , 2 a ) , i s a vo lt age prop or t i on a l to ang u l a r r a t e ab out t h e a x i s nor m a l to t h e top su r f a c e of t h e p a c k a g e (s e e f i gur e 2). a sin g le ext e r n al r e sis t o r ca n be us e d t o lo w e r t h e s c ale f a c t o r . an ext e r n al ca p a c i t o r is us e d t o s e t t h e b a ndwi d t h . o t her ext e r n al ca p a ci t o rs a r e r e q u ire d fo r o p era t ion (see f i gur e 1). a p r e c isio n r e fer e n c e and a t e m p era t ur e o u t p u t a r e als o p r o v i d ed f o r co m p en sa ti o n t e ch n i q u e s . t w o d i gi tal se l f - t e s t i n put s el e c t r ome c h a ni c a l l y e x c i te t h e s e ns or to te st prop e r o p er a t ion o f b o t h s e n s o r s and t h e sig n a l condi t i o n in g cir c ui ts. func tio n a l block di agram 5g 4g 3a 5v 2g 1f 7f 6a 7d 7c 7b 1c 4a 5a 7e 6g 1d 2a 1e 3g 1b pdd 12v + adxrs401 1 f 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 s sen 2 r sen 1 c out r out 180k ? 1% 9k ? 35% 9k ? 35% sumj 2.5v ref resonator loop ? 04992-001 fi g u r e 1 .
adxrs401 rev. 0 | page 2 of 12 table of contents specifications ..................................................................................... 3 absolute maximum ratings ............................................................ 4 rate-sensitive axis ....................................................................... 4 pin configuration and function descriptions ............................. 5 typical performance characteristics ............................................. 6 theory of operation ........................................................................ 8 supply and common considerations ....................................... 8 setting bandwidth ........................................................................ 9 increasing measurement range ................................................. 9 temperature output and calibration ........................................ 9 use with a supply-ratiometric adc ....................................... 10 null adjust ................................................................................... 10 self-test function ....................................................................... 10 acceleration sensitivity ............................................................. 10 outline dimensions ....................................................................... 12 ordering guide ........................................................................... 12 revision history 7/04revision 0: initial version
adxrs401 rev. 0 | 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. parameter conditions min typ max unit sensitivity top view clockwise ro tation is positive output dynamic range 1 full-scale range, ?40c to +85 c 75 /s scale factor ?40c to +85 c 12.75 15 17.25 mv//s nonlinearity best fit straight line 0.1 % of fs null initial null 2.50 v turn-on time power on to ?/s of final 35 ms linear acceleration effect any axis 0.2 /s/ g noise performance rate noise @ 10 hz bandwidth 3 mv (rms) frequency response 3 db bandwidth 2 (user selectable) 22 nf as c out (see setting bandwidth section) 40 hz sensor resonant frequency 14 khz self test st1 rateout response 3 st1 pin from logic 0 to 1 ?800 mv st2 rateout response 3 st2 pin from logic 0 to 1 +800 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 2.5 v load drive to ground source 200 a load regulation 0 < i out < 200 a 5.0 mv/ma power supply operating voltage range 4.75 5.00 5.25 v quiescent supply current 6.0 8.0 ma temperature range operating temperature range ?40 +85 c 1 dynamic range is the maximum full-scale measurement range possible, including output swing range, initial offset, sensitivity, offset drift, and sensitivity drift at 5 v supplies. 2 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 s section. etting bandwidth 3 self-test response varies with temperature. see the section for details. self-test function
adxrs401 rev. 0 | page 4 of 1 2 absolute maximum ratings table 2. p a r a m e t e r r a t i n g acceleration (any axis , unpowered, 0.5 ms) 2000 g acceleration (any axis, powere d, 0.5 ms) 2000 g +v s ? 0.3 v to +6.0 v output short-ci rcuit duration ( a ny pin to common) indefinite operating tem p erature range ? 55c to +125c storage temperature ? 65c to +150c s t r e s s es a b o v e t h os e lis t e d u n de r t h e a b s o l u t e m a xim u m r a tin g s m a y ca use pe rm a n en t d a ma g e t o t h e devi ce . t h is i s a st re ss r a t i n g on l y ; f u nc t i on a l op e r a t i o n of t h e d e v i c e a t t h e s e or a n y o t h e r con d i t io n s ab o v e t h o s e i n dica t e d in t h e op era t io nal s e c t io n o f t h is sp e c if ic a t io n is no t im plie d . e x p o sur e t o a b s o l u te max i m u m ra t i ng co ndi t i on s fo r ex ten d e d p e r i o d s ma y a f fe c t de vice r e l i ab i l i t y . a p p l ica t ion s r e q u ir in g m o r e tha n 200 c y c l es t o mil - s t d-883 m e th o d 1010 c o n d i t ion b (C55 c t o +125c) r e q u ir e u n der f il l or ot he r me ans to a c h i e v e t h i s re qu i r e m e n t . d r op s on to h a rd su r f a c e s c a n c a u s e s h o c k s of g r e a te r t h an 2000 g and exce e d t h e a b s o l u t e maxim u m ra t i ng o f t h e de v i ce . c a r e sh o u ld b e exer cis e d in hand lin g to a v o i d d a ma ge. esd caution esd (electrostatic discharge) sensitive device. ele c tros tatic charg e s as high as 4000 v readily accumulate on the human body and test eq uipment and can discharge wi thout detection. although this product features proprietary esd protection circu i try, permanent dama ge may occur on devices subjected to high energy electrostatic discharges. theref ore, prop er esd precautions a r e recommended to avoid perform a nce degradation or l o ss of functiona l ity. rate-sensi tive a x is this z - axis ra te -s en sing de vic e is a l s o ca l l e d a y a w-r a t e s e n s ing de vice . i t p r o d u c es a p o si t i ve-go in g o u t p u t v o l t a g e fo r clo c kwis e r o ta ti o n a b o u t t h e a x i s n o rm al t o th e pa c k a g e t o p (c loc k w i s e w h en lo oki n g do wn a t t h e p a cka g e lid). 2.5 v rate axis ra t e o u t rate in gn d 4. 7 5 v 0. 25 v late ral ax is ab cde fg 7 a 1 1 longitudinal axis v cc = 5v 04992-002 f i gure 2. r a teout signal in cr ea ses with cl ock w i s e ro ta t i o n
adxrs401 rev. 0 | page 5 of 1 2 pin conf iguration and fu nction descriptions 04992-020 agnd temp st2 st1 pgnd avcc cp1 cp2 cp4 rateout gf e d c b a 7 6 5 4 3 2 1 cp5 cp3 pdd cmid sumj 2.5v f i g u re 3. bg a- 32 ( b ot to m vi ew) ta ble 3. pi n f u nct i on d e s c ri pt i o ns pin no. mnemonic description 6d, 7d cp5 hv filter capacitor to ground C 1 f 20 v minimum 6a, 7b cp4 charge pump capacitor C 22 nf 6c, 7c cp3 charge pump capacitor C 22 nf 5a, 5b cp1 charge pump capacitor C 22 nf 4a, 4b cp2 charge pump capacitor C 22 nf 3a, 3b avcc + analog supply 1b, 2a rateout rate signal output 1c, 2c sumj output amp summing junction 1d, 2d cmid hf filter capacit o r C 100 nf 1e, 2e v2.5 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
adxrs401 rev. 0 | page 6 of 1 2 typical perf orm ance cha r acte ristics @ b w = 40 h z , t y p i cal v i b r a t ion cha r ac t e r i s t ic s, 10 g fla t b a n d , 20 h z t o 2 kh z. 30 25 20 15 10 5 0 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5 04992-003 output in volts % of population f i gur e 4 . ini t ia l null output 20 18 16 14 12 10 8 6 4 2 0 ? 1 0 ? 8 ? 6 ? 4 ? 2 0 2468 1 0 04992-004 null shift in mv/ c % of population fi g u r e 5 . n u l l t e m p c o 40 35 30 25 20 15 10 5 0 13.50 14.00 14.50 15.00 15.50 16.00 16.50 04992-005 sensitivity in mv/degree/second % of population f i g u re 6. in it i a l s e n s it iv it y 30 25 20 15 10 5 0 ? 8 ?6 ?4 ?2 0 2 4 8 6 04992-006 % sensitivity shift over temperature % of population f i g u re 7. s e ns it iv it y chang e o v e r t e m p er at u r e 2.50 2.49 2.48 2.47 2.46 2.45 05 04992-007 time (seconds) package lateral axis (1/60 sec sample rate) rate o ut (v ) 1 0 f i g u re 8. 10 g ra nd om vibr at i o n in p a ck ag e - lat e r a l a x is o r ient at i o n 05 04992-008 time (seconds) package longitudinal axis (1/60 sec sample rate) rate o ut (v ) 1 0 2.50 2.49 2.48 2.47 2.46 2.45 f i g u re 9. 10 g ra nd om vibr at i o n in p a ck ag e - l o ng it udi n a l a x is o r i e nt at ion
adxrs401 rev. 0 | page 7 of 1 2 1 0 2.50 2.49 2.48 2.47 2.46 2.45 05 04992-009 time (seconds ) rate axis (1/60 sec sample rate) rate o ut (v ) f i g u re 10. 1 0 g r a n d om vibr at i o n in r a te a x is o r i e nt at i o n 2.50 2.49 10 g 0 g 2.48 2.47 2.46 2.45 05 04992-010 time (seconds) package lateral axis (0.5s average) rate o ut (v ) 1 0 f i g u re 11. 1 0 g r a n d om vibr at i o n in p a ckag e - l a te r a l a x i s o r ient at i o n 2.50 2.49 0 g 10 g 2.48 2.47 2.46 2.45 05 04992-011 time (seconds) package longitudinal axis (0.5s average) rate o ut (v ) 1 0 f i g u re 12. 1 0 g r a n d om vibr at i o n in p a ckag e - l o ng it udin al a x is o r ie nt at i o n 2.50 2.49 0 g 10 g 2.48 2.47 2.46 2.45 05 04992-012 time (seconds) rate axis (0.5s average) rate o ut (v ) 1 0 f i g u re 13. 1 0 g r a n d om vibr at i o n in r a te a x is o r i e nt at i o n
adxrs401 rev. 0 | page 8 of 1 2 theory of operation 04992-013 agnd temp st2 st1 pg n d cp1 cp2 cp4 rateout cp4 pdd cmid sumj c out = 22nf 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 22nf avcc 100nf 100nf pgnd 22nf 1 f 5v f i gure 14. e x a m pl e a p plic ati o n c i rcu i t ( t op vie w ) note t h at inn e r r o ws /c o l u m ns of p i ns have b een o m it t e d f o r cl ar it y but s h ou ld be c o n n ec t e d in t h e a p pl ic at io n. the a d x r s401 o p era t es on t h e p r in ci ple o f a res o na t o r g y r o . t w o p o ly s i l i c o n s e ns ing st r u c t u r e s e a ch c o n t ai n a di t h e r f r ame, wh i c h i s e l ectr os ta ticall y d r i v e n t o r e so n a n c e . th i s p r od uce s t h e n e ce s s a r y v e l o c i t y e l e m en t t o p r o d uce a c o r i olis fo r c e d u r i n g a n gu la r ra te . a t tw o o f t h e o u t e r ext r em es o f e a ch f r a m e , o r t h og o n al t o t h e di t h er m o t i on, a r e m o va b l e f i n g ers t h a t a r e place d b e tw e e n f i xe d p i ck o f f f i ngers to fo r m a ca p a ci t i ve p i ck o f f s t r u c t ur e t h a t s e n s es c o r i olis mo t i o n . the r e su l t in g si g n a l is fe d to a s e r i es o f ga in a nd de m o d u l a t i on s t a g es t h a t p r o d uce t h e e l e c t r ica l ra t e sig n al o u t p u t . th e d u al - s e n s o r desig n r e j e c t s ex ter n a l g- fo r c es a n d v i b r a t io n. f a b r i c a t in g t h e se n s o r wi th t h e si gn al co n d i ti o n i n g e l ectr o n i c s p r es er v e s sig n al in teg r i t y in n o i s y en vir o nm e n t s . the e l ec tr os t a tic r e s o na t o r r e q u ir es 14 v t o 16 v f o r o p era t io n. sin c e o n ly 5 v i s ty p i ca l l y a v a i l a b l e in m o st a pplica t ion s , a c h a r g e p u m p is in c l uded on-c hi p . i f a n ext e r n al 14 v t o 16 v s u p p l y is a v ailab l e , th e tw o c a p a ci t o rs o n cp1 to cp4 ca n be o m i t te d and t h i s su p p ly can b e co nne c t e d to c p 5 (pin 7d) wi t h a 1 f deco u p lin g ca p a c i t o r . af t e r t h e de m o d u l a t i o n s t a g e t h er e is a si n g le- p ole lo w-p a s s f i l t er co n s is tin g o f a n in t e r n al 9 k? r e sis t o r (r sen1 ) a nd a n e x t e rn al u s e r - s u p p l i e d ca pa ci t o r ( c m i d ) . a c m i d c a pa ci t o r o f 100 nf s e ts a 40 0 h z lo w-p a s s p o le 35% a nd is us ed t o limi t hig h f r e q ue n c y a r t i fac t s b e fo r e f i na l a m plif ic a t i o n. a b a ndwi d t h limi t ca p a c i t o r , c ou t , s e ts th e p a s s ban d wid t h (s ee s e t t ing b a ndwi d t h s e c t i o n). suppl y a n d c o mmo n c o nsider a t io ns o n ly p o we r su ppl ie s u s e d for su p p ly ing ana l o g c i rc u i ts are r e co mmen d e d f o r p o w e r i n g th e ad xrs401. h i g h f r eq uen c y n o is e an d t r a n si en ts as s o c i a t e d wi t h dig i t a l c i r c ui t s u p p lies ma y ha v e ad v e rs e a f fe c t s o n de vice op era t ion. 1 f s h o w s t h e r e co mmen d e d c o nn ec t i o n s f o r th e ad xrs401 wher e bo t h a v c c an d pdd ha ve a s e p a ra t e de co u p l i n g c a p a ci t o r . t h es e sh o u ld b e place d as clos e t o t h e i r r e sp e c t i ve pins as p o ssib le b e fore rou t ing to t h e s y ste m an a l o g su p p ly . this wi l l m i ni mi ze th e n o i s e i n ject ed b y th e c h a r g e p u m p tha t uses th e p d d s u p p l y . i t is als o r e co mm en ded t o p l ac e th e c h a r g e p u m p c a p a ci t o rs co nnec t e d t o t h e cp1 t o cp4 p i n s as c l os e t o the p a r t as p o s s i b le . th e s e ca p a c i t o rs a r e us e d t o p r o d uce t h e on-chi p hig h v o l t a g e s u p p l y s w i t ch e d a t t h e di t h er f r e q ue n c y a t a p p r o x im a t ely 14 khz. c a r e sh ou ld b e t a k e n t o en sur e t h a t th e r e i s n o m o r e th a n 50 pf o f s t ra y ca pa ci ta n c e bet w een c p 1 to cp4 an d g r ound . s u r f ace-mo un t ch i p c a p a ci to rs a r e sui t a b l e as lo n g as t h e y ar e ra t e d fo r o v er 15 v .
adxrs401 rev. 0 | page 9 of 1 2 setti ng ba ndwi dth e x t e r n al ca p a ci to rs cmid an d c ou t a r e us e d i n co m b in a t ion wi t h on -ch i p re s i stors to c r e a te two l o w-p a ss f i lte r s to l i mit t h e b a ndwi d t h o f t h e ad xrs401 s r a te r e sp o n s e . t h e C3 db fr e q u e n c y s e t b y r ou t and c ou t is: ( ) out out out c r 2 1/ f = t h i s f r eq u e n c y c a n be w e ll c o n t r o ll ed s i n c e r ou t h a s been tr imm e d d u r i n g ma n u fac t ur ing t o be 180 k? 1%. an y ext e r n al r e sisto r a p plie d b e tw e e n t h e r a teou t (1b , 2a) a nd s u mj (1c, 2c) p i n s will r e s u l t in: () ( ext ext out r k 180 / r k 180 r + = ) the ?3 db f r eq uen c y is s e t b y rs en (t h e p a ra l l e l co m b ina t ion of r sen1 an d r se n2 ) a t abo u t 4.5 k? n o minal . c m id is les s w e l l co n t r o l l ed , be c a us e r sen1 a nd r sen2 h a v e been us ed t o tri m t h e r a t e s e n s it i v it y du r i n g m a n u f a c t u r i n g a n d h a v e a 3 5 % to l e r a nc e. i t s pr i m ar y pu r p o s e i s to l i m i t t h e h i g h f r e q u e nc y d e m o d u la ti o n a r ti fa ct s f r o m sa t u ra ti n g t h e f i n a l a m p l i f i e r s t a g e . th us, this p o le o f n o minal l y 40 0 h z @ 0.1 f need n o t be p r ecis e . l o w e r f r eq uen c y is p r ef era b le , b u t i t s var i a b il i t y us ual l y re qu i r e s i t to b e ab out 1 0 t i me s g r e a te r ( i n orde r to pre s e r ve p h a s e in t e gri t y) th a n th e w e ll- co n t r o ll ed o u t p u t po l e . i n g e n e ral , bo th ?3 db f i l t er f r eq uen c ies sho u ld be s e t as lo w as p o s s ib le t o r e d u ce t h e am pl i t ude o f t h es e hi g h f r e q uen c y a r t i fac t s, as we l l as t o r e d u ce t h e o v eral l sys t em n o i s e . increasing measurement range t o in cr eas e the f u l l -s cale m e as u r em en t ra n g e o f th e ad xrs401, place an ext e r n al r e sis t o r b e t w e e n t h e r a te o u t (1b , 2a) a nd s u mj (1c, 2c) p i n s . this p a ral l e ls th e in ter n al r ou t re s i stor t h a t is fac t o r y-tr imm e d t o 180 k?. f o r exa m p l e , a 330 k? ext e r n al r e sis t o r g i v e s a p p r o x ima t e l y 10mv//s e c s e nsi t ivi t y a nd a commen s ura t e 50 % in c r ea se i n t h e f u l l -s ca le ran g e . this is ef fe c t i v e fo r u p t o a 4 in cr e a s e in t h e f u l l -s cale ran g e . (th e mini m u m va l u e o f t h e p a ral l e l r e sis t o r allo w e d i s 45 k?.) b e y o n d t h i s a m o u n t o f ext e rn al sen s i t i v i t y re d u c t i o n , t h e i n te r n a l c i rc u i t r y he a d ro o m re q u i r e m e n t s p r ev e n t fur t h e r i n cr ease in th e li n e a r full - s cal e o u t p u t ra n g e . the dra w b a cks o f m o dif y i n g t h e f u l l -s cale ra n g e a r e t h e a d d i t i on a l output n u l l d r i f t ( a s m u ch a s 2 / s e c ove r t e m p era t ur e) and t h e r e ad j u s t men t o f t h e ini t i a l n u l l b i as. s e e n u l l a d j u st s e c t io n an d a p plic a t io n n o t e an -6 25 fo r det a i l s. temperatu r e outpu t and c a libratio n i t i s c o m m on pr a c t i c e to te m p e r a t u r e - c a l i b r a t e g y ro s to im p r o v e t h e i r o v era l l acc u rac y . the a d x r s401 has a te m p e r atu r e - pr op or t i on a l vo lt a g e output t h at prov i d e s i n put to s u c h a c a l i b r at i o n m e t h o d . t h e v o l t a g e at t e m p ( 3 f , 3 g ) i s n o minal l y 2.5 v a t 27c an d has a p t a t (p r o p o r t io nal t o a b s o l u t e t e m p er a t ur e) cha r ac ter i s t ic o f 8.4 mv/ c. n o te t h a t t h e temp o u t p u t cir c ui tr y is limi t e d t o 50 a s o urce c u r r en t. l i m i t i ng t h e b a nd w i d t h of t h e d e v i c e re d u c e s t h e f l a t - b a n d n o is e d u r i n g t h e ca lib r a t io n p r o c ess, im p r o v ing t h e m e as ur em en t accura c y a t ea c h cali b r a t i o n po i n t . 5g 4g 3a 5v 2g 1f 7f 6a 7d 7c 7b 1c 4a 5a 7e 6g 1d 2a 1e 3g 1b pdd 12v + adxrs401 1 f 22nf 100nf 22nf cp2 cp1 pgnd cp4 cp3 cp5 charge pump/reg. temp ptat rate- out 2.5v demod rate sensor self test 100nf 100nf cmid agnd avcc st1 st2 coriolis signal channel s sen 2 r sen 1 c out r out 180k ? 1% 9k ? 35% 9k ? 35% sumj 2.5v ref resonator loop ? 04992-014 f i g u re 15. bl ock d i ag r a m wit h e x t e rn al co mpo n ent s
adxrs401 rev. 0 | page 10 of 12 use with a supply-ra tiome t ric adc the a d x r s401 s r a te out si g n a l is n o nr a t iom e t r ic (t ha t is, n e i t her t h e n u l l v o l t a g e n o r t h e ra t e s e n s i t iv i t y i s p r o p o r t i o n al t o t h e s u p p ly ) . r a t h e r , t h e y are nomina l l y c o nst a n t for dc su p p ly c h a n g e s wi thin th e 4.75 v t o 5.25 v o p era t in g ra n g e . i f th e ad xrs401 is us ed wi t h a s u p p ly-ra t iom e tr ic ad c, th e ad xrs401 s 2. 5 v o u t p u t can be con v er t e d and us ed t o ma k e co rr ecti o n s i n s o ft w a r e f o r th e s u p p l y v a ri a t i o n s . null adjust n u l l adj u st me n t is p o ss ibl e b y i n j e c t i n g a su i t abl e c u r r e n t to s u mj (1c, 2c). s i m p l y add a s u i t a b le r e sis t o r t o ei ther th e g r ou nd or t h e p o s i t i ve supply . t h e nom i n a l 2 . 5 v n u l l i s f o r a sy m m et r i ca l s w in g r a n g e a t r a teou t ( 1 b , 2a) . i n s o m e a p plic a t ion s , a no n s y m m e t r ica l o u t p ut s w in g m a y b e sui t ab le . i f a re s i stor is c o nne c te d to t h e p o s i t i ve sup p ly , su p p ly dist ur b a n c es m a y r e f l e c t s o m e n u l l in st a b i l i t y . a v o i d dig i t a l su p p ly n o is e , p a r t ic u l a r ly in t h is cas e (s e e t h e s u p p ly a nd co m m o n co n s i d e r a t i o n s s e c t i o n ) . the r e sis t o r val u e t o us e is a p p r o x ima t e l y : ) v C v 180,000)/( (2.5 r null1 null0 null = v nu ll0 is t h e un ad j u st e d zer o ra t e o u t p u t , and v nu ll1 is t h e t a rg et n u l l val u e . i f t h e ini t ial val u e is b e lo w t h e desir e d val u e , t h e re s i stor shou l d t e r m i n a t e on c o m m o n or g r ou n d . i f it i s a b ove t h e desir e d val u e , t h e r e sis t o r sho u ld t e r m ina t e o n t h e 5 v s u p p l y . v a l u es t y p i cal l y a r e in t h e 1 m? t o 5 m ? ra n g e . i f a n ext e r n al r e sis t o r is us ed ac r o s s ra te o u t a nd s u mj , t h e p a ral l e l e q ui val e n t val u e is s u b s t i t u t e d in t o t h e a b o v e e q ua t i on. n o t e t h a t t h e r e sis t o r val u e is an es t i ma te si n c e i t ass u m e s v cc = 5.0 v a n d v su m j = 2.5 v . self-test functi on the a d x r s401 in cl udes a s e lf-tes t fe a t ur e t h a t st im u l a t es e a ch o f t h e s e n s i n g s t r u c t ur es a n d as s o ci a t e d e l e c t r o n ics in t h e s a me man n e r , a s i f su b j e c te d to ang u l a r r a te. i t i s a c t i v a te d b y s t anda r d log i c hig h leve ls a p p l ie d t o in p u ts s t 1 (5f , 5g) , s t 2 (4f , 4g), o r b o t h . s t 1 ca us es t h e v o l t a g e a t r a teo u t t o c h a n g e abo u t ? 0 .800 v , a nd s t 2 ca us es an o p p o si t e +0.800 v . a c t i v a t i ng b o t h st 1 a n d st 2 s i m u lt a n e o u sly i s not d a m a g i ng . b e ca us e s t 1 and s t 2 a r e n o t neces s a r il y c l os e l y ma t c h e d , ac t u a t i n g b o t h s i m u l t ane o u sly ma y re su l t i n an a p p a re n t n u l l bi a s s h i f t . accelerati on sens iti v it y t h e si gn co n v en ti o n use d i s tha t la t e ral acce le ra ti o n i s posi ti v e in t h e d i r e c t io n f r o m pin c o l u mn a to pin c o l u mn g o f t h e p a cka g e . tha t is , a de vice h a s p o si t i v e s e n s i t iv i t y if i t s v o l t a g e o u t p ut in cr e a s e s w h en t h e r o w o f p i n s 2a t o 6 a a r e t i pp e d un der t h e r o w 2g t o 6g in t h e e a r t h s g r a v i t y . ther e a r e tw o e f fe c t s o f co n c er n: s h if ts in t h e st a t ic n u l l an d ind u ce d n u l l n o is e . s c a l e fac t o r is n o t sig n if ican t l y a f fe c t e d un t i l acce lera tio n r e ac h e s s e v e ral h u n d r e d m e t e r s p e r seco n d sq u a r e d . v i b r a t io n r e c t if ica t ion fo r f r e q uen c ies u p t o 20 khz is o f t h e o r der o f 0.0000 2(/s)/(m/s 2 ) 2 in t h e p r ima r y axis a nd 0.0003(/s)/(m/s 2 ) 2 f o r a c c e l e r a t i on appl i e d a l o n g a d i agon a l of t h e li d . i t is n o t sig n if ica n t l y de p e nden t o n f r e q uen c y , a nd ha s been v e r i f i ed u p t o 300 m/s 2 rm s . l i ne ar v i b r a t i o n sp e c t r a l d e ns i t y ne ar t h e 1 4 k h z s e ns or r e s o na n c e tra n sla t es in t o o u t p u t n o is e . i n o r der t o ha v e a sig n if ica n t ef fe c t , t h e v i b r a t io n m u st b e wi t h in t h e an gu la r ra te ba ndwid th (typ ical l y 40 h z o f th e r e s o nan c e), s o i t ta k e s c o ns i d e r abl e h i g h f r e q u e nc y v i b r a t i o n to h a ve an y e f fe c t . a w a y f r o m t h e 14 kh z r e s o nance , t h e ef fe c t is n o t dis c er nib l e , excep t fo r vi b r a t io n f r e q uen c ies wi t h in t h e a n g u la r ra t e p a ss b a nd . th e in-b and ef fe c t ca n b e s e en i n f i gur e 17. this is t h e re su l t of t h e st a t ic g - s e ns it iv ity . the sp e c i m e n u s e d for f i g u re 1 7 had a g - s e n s i t ivi t y o f 0.15 /s/g and i t s to t a l i n - b a nd n o is e deg r ade d f r o m 3 mv r m s t o 5 mv r m s f o r th e s p ecif ie d vib r a t io n. t h e e f fe c t o f b r o a d b a nd v i b r a t ion u p is sh own i n f i gur e 18 a nd f i gur e 19. the o u t p u t n o is e o f t h e p a r t fal l s a w a y in ac co r d an c e w i t h t h e o u t p ut lo w-p a ss f i l t er a nd do es n o t con t ain an y sp i k es g r e a ter t h a n 1% o f t h e l o w f r e q uen c y no is e . a ty pica l no is e sp e c t r um is s h own in f i gur e 16. ?6 0 ?7 0 ?8 0 ?9 0 ?100 ?110 ?120 ?130 0 1 0 100 1k 10k 100k 04992-015 frequency (hz) rate o ut (v ) f i gure 16. no ise s p ec tr a l d e ns it y at r a te out C b w = 4 h z
adxrs401 rev. 0 | page 11 of 12 1 0 2.60 2.50 2.52 2.54 2.56 2.58 02 46 8 04992-016 time (seconds) rate o ut (v ) f i g u re 17. ra ndo m vibr at ion (lat er al) 2 h z t o 40 h z 3. 2 g rms 2.60 2.50 2.52 2.54 2.56 2.58 02 46 8 04992-017 time (seconds) rate o ut (v ) 1 0 f i g u re 18. ra ndo m vibr at ion (lat er al) 10 k h z to 2 0 k h z at 0. 0 1 g / h z wit h 60 h z s a mp ling an d 0. 5 s ec a v e r ag in g 2.60 2.58 2.56 2.54 2.52 2.50 02 46 8 04992-018 time (seconds) rate o ut (v ) 1 0 shaking 2.5mv rms static 0.8mv rms f i g u re 19. ra ndo m vibr at ion (lat er al) 10 k h z to 2 0 k h z at 0. 0 1 g / h z wit h 60 h z s a mp ling an d 0. 5 s ec a v e r ag in g 0.07 0 0.01 0.02 0.03 0.04 0.05 0.06 0 1 0 100 04992-019 time (seconds) /s f i g u re 20. r oot a l l e n v a r i anc e v s . a v er ag ing ti me
adxrs401 rev. 0 | page 12 of 12 outline dimensions a b c d e f g b o t t o m v i e w 76 54 3 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 f i g u re 21. 3 2 -l ead chip s c a l e ba ll gr id a r r a y [cs p bg a ] (bc-32) di me nsio ns sho w n i n mi ll im e t e r s ordering guide model temperature r a nge package descri ption package outlin e adxrs401abg ? 40c to +85c 32-lead bga bc-32 adxrs401abg- r eel ? 40c to +85c 32-lead bga bc-32 a d x r s 4 0 1 e b e v a l u a t i o n boar d ? 2004 anal og de vices, inc. all ri ghts rese rved. tra d emarks a n d registered tra d ema r ks are the prop erty o f their respective ow ners. c04992C0 C 7/04(0)

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