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64- position otp digital potentiometer ad5171 fea t ures 64 positions otp (one-time programmable ) 1 set-and-forget resistance settinglow cost alternative over eemem unlimited adjustments prior to otp activation 5 k?, 10 k?, 50 k?, 100 k? en d-to-end r e sist ance low tempc o 5 ppm/ o c in pote ntiometer mode rev. pr c low tempco 35 ppm/c in rhe o stat mode compact standard sot-23 -8 p a ckage low power, i dd = 8 a max fast settling ti me, t s = 5 s typ in power-up i 2 c compatible digital interf ace computer software replaces c in factory programming applications full re ad/write of wiper register extra i 2 c de vice addr ess pin power-on preset to midscale 6 v one-time programming voltage low operating voltage, 2.7 v t o 5.5 v otp v a lid a tion check fu nction automotive te mperature ran g e ?40 c to + 1 25c a pplic a t io ns systems calibr ations electronics level settings mechanical pot e ntiometers an d trimmers? re placements automotive e l ectronics adjustments gain control and offset a d just ments transducer circ uits a d justmen t s programmable filters up to 1. 5 mhz bw gener a l de scription the ad5171 is a 64-p o si tion, on e-tim e p r og ramma b l e (otp) di g i t a l p o te n t i o me te r 2 , whic h e m p l o y s f u s e link t e c h n o log y t o achie ve t h e m e m o r y r e t e n t ion o f r e sis t a n ce s e t t in g f u n c t i o n . o t p is a cos t -ef f e c t i v e al t e r n a t iv e o v er t h e eemem a p p r o a ch for u s e r s w h o d o not ne e d to re pro g r a m n e w m e mor y s e tt i n g i n t h e d i g i t a l p o te n t i o me te r . th i s de v i c e p e r f or ms t h e s a me e l ectr o n i c a d j u stm e n t fun c ti o n lik e m o st m e c h a n i c al tri m m e r s a nd va r i ab le r e sis t o r s do . th e ad5171 is p r og ra mmed usin g a 2-wir e i 2 c co m p a t ib le dig i tal c o n t r o l . i t al lo ws unlimi t e d a d j u st me n t s b e f o re p e r m ane n t l y s e tt i n g t h e re s i st a n c e v a lu e. duri n g th e o t p a c ti v a t i o n , a p e rm a n en t fuse b l o w n co m m a n d is s e n t a f t e r t h e f i nal val u e is de t e r m ine d ; t h er efo r e f r e e z in g t h e w i pe r pos i ti o n a t a gi v e n set t i n g ( a n a l o g o u s t o p l a c i n g epo x y o n a me cha n i c a l t r i mmer). w h e n t h is p e r m an en t s e t t i n g is achie v e d , t h e v a l u e wi l l not ch ange re g a rd l e ss of su p p ly va r i a t ion s o r e n vir o nm e n t a l st r e s s es under n o r m al o p era t in g co n d i ti o n s. t o v e ri f y th e s u cce s s o f pe rm a n e n t p r ogra m m i n g , a n alog dev i ce s pa t t e r n e d th e o t p v a lida ti o n s u c h th a t th e fuse st a t us can b e di s c er n e d f r o m t w o va lid a t i on b i ts in r e a d m o de. f o r a p p l ica t ion s tha t p r og ra m ad5171 in t h e fac t o r ies, analog d e vices o f fers a de vice p r og rammin g s o f t w a r e , w h ich op era t e s acr o ss w i n d o w s ? 95 t o xp? pla t fo r m s in cl ud in g w i n d o w s nt?. this s o f t wa r e a p plica t io n ef fe c t i v e l y r e places t h e n e e d fo r ext e r n al i 2 c co n t r o l l ers o r h o s t p r o c es s o rs an d t h er efo r e sig n if ica n t l y r e d u ces us ers de v e l o p m e n t t i m e . an ad5171 eva l ua tion k i t is a v a i la b l e , which inc l udes th e s o f t wa r e , co n n e c to r , a n d ca b l e t h a t c a n b e con v er te d fo r t h e f a c t o r y p r o g r a m m i n g ap p l i c at i o n s . the ad5171 is a v a i la b l e in a com p ac t sot - 23 -8 p a c k a g e . al l p a r t s a r e gua r a n t e e d t o o p era t e o v er t h e a u t o mo t i v e t e m p era t ur e ra ng e o f ?40c t o +125c. b e sides i t s uniq ue o t p f e a t ur e , the ad5171 len d s i t s e lf w e l l t o o t h e r g e n e ral-p u r p os e di g i t a l p o te n t i o me te r a p pl i c a t i o ns d u e to i t s te m p e r a t u r e pe rf o r m a n c e , s m all f o rm f a ct o r , a n d l o w c o s t . gnd i 2 c interface and control logic a w b wiper register fuse link v dd ad0 sda scl ad5171 03437-0-001 fi g u r e 1 . f u nct i o n al bl oc k dia g r a m top view (not to scale) 8 7 6 5 1 2 3 4 w v dd gnd scl a b ad0 sda ad5171 03437- 0- 002 f i gure 2. pin config ur ation 1 one-t ime programmabl e ( o t p ) - unl i mit ed ad jus t ments be f o re permanent s e tting. 2 the te rms d i gital p o te ntio m e t e r and r d a c are us ed inte rchange a bl y. 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 ? 2003 analog de vices, i n c. al l r i ght s r e ser v ed .
ad5171 table of contents ad5171e l ec tr ical c h a r ac t e r i s t ics .............................................. 3 a b s o l u t e m a xim u m r a t i n g s ............................................................ 5 es d c a u t ion .................................................................................. 5 p i n c o nf igura t io n an d f u n c t i onal d e s c r i p t io ns .......................... 6 t y p i cal p e r f o r ma n c e c h a r ac t e r i s t ics ............................................. 7 the o r y o f o p era t io n ...................................................................... 11 on e - t i me p r og ra mmin g (otp ) .............................................. 11 d e t e r m inin g t h e v a r i a b le resist a n ce and v o l t ag e ................. 11 r h e o s t a t m o de o p era t ion ..................................................... 11 p o t e n t iomet e r m o de o p era t ion ........................................... 12 es d p r o t e c t i on ........................................................................... 12 t e r m inal v o l t a g e o p era t in g r a n g e .......................................... 13 p o w e r - u p /p o w er -d o w n s e q u e n ces ......................................... 13 p o w e r s u p pl y c o n s idera t ion s ................................................... 13 c o n t r o l l in g th e ad5171 ............................................................ 14 s o f t w a r e p r og ra mmin g ......................................................... 14 i 2 c c o n t r o l l er p r og ra mmin g ................................................ 15 c o n t r o l l in g t w o d e v i ces o n o n e b u s ..................................... 16 a p plica t ion s ..................................................................................... 17 p r og ra mma b l e v o l t a g e refer e nce (d a c ) . .............................. 17 ga in c o n t r o l c o m p e n s a t i on .................................................... 17 p r og ra mma b l e v o l t a g e s o ur ce wi t h b o os te d o u t p u t ............ 17 l e ve l s h if t i n g fo r dif f er en t v o l t a g e o p er a t ion . ..................... 17 resis t an c e s c alin g ...................................................................... 17 res o l u t i on enha n c e m en t .......................................................... 18 rd a c c i r c ui t sim u l a t i on m o del . ............................................ 18 ad5171 e v al u a tio n b o a r d . ....................................................... 19 o u t l in e dim e n s io n s ....................................................................... 20 or der i n g g u ide . ......................................................................... 20 revisi on h i s t or y rev i s i o n 0: i n i t ial v e r s i o n r e v. pr c | pa g e 2 of 20
ad5171 electrical characteristics table 1. 5 k?, 10 k?, 50 k?, a n d 100 k? versions, v dd = 3 v to 5 v 10%, v a = v dd , v b = 0 v, ?40 c < t a < +125c , unles s ot herwi s e not e d. p a r a m e t e r s y m b o l c o n d i t i o n s m i n typ 1 m a x u n i t dc charac teri stics rh eosta t mode resistor differential nonlin earit y 2 r - d n l r wb , v a = no connect, r ab = 10 k?, 50 k ? , and 100 k? 0 . 5 0 . 2 + 0 . 5 l s b r wb , v a = no connect, r ab = 5 k? 1 0 . 2 5 + 1 l s b resistor integral nonlinearity 2 r - i n l r wb , v a = no connect, r ab = 10 k? , 50 k ? , and 100 k? 1 0 . 2 5 + 1 l s b r wb , v a = no connect, r ab = 5 k? 1 . 5 0 . 5 + 1 . 5 l s b nominal resi sto r t o lerance 3 r ab /r ab 3 0 + 3 0 resistance tem p erature coefficient (r ab /r ab )/t 3 5 p p m / c wiper resistanc e r w v dd = 5 v 60 115 ?
ad5171 p a r a m e t e r s y m b o l c o n d i t i o n s m i n typ 1 m a x u n i t dynamic ch aracteris t ics 6, 10, 11 bandwidth 3 db bw5k r ab = 5 k?, code = 0x20 1500 khz b w 1 0 k r ab = 10 k?, code = 0x20 600 khz b w 5 0 k r ab = 50 k?, code = 0x20 110 khz bw100k r ab = 100 k?, co de = 0x20 60 khz t o tal harmonic distortion t h d v a =1 v rms, r ab = 10 k?, v b = 0 v d c , f = 1 khz 0 . 0 5 adjustment settling time t s1 v a = 5 v 1 lsb error band, v b = 0, measured at v w 5 s otp settling ti me 12 t sot p v a = 5 v 1 lsb error band, v b = 0, measured at v w 4 0 0 m s power-up settling t imepost fuses blo w n t s2 v a = 5 v 1 lsb error band, v b = 0, measured at v w 5 s resistor noise v o ltage e nwb r ab = 5 k?, f = 1 khz, code = 0x20 8 n v / h z r ab = 10 k?, f = 1 khz, code = 0x20 1 2 n v / h z interf ace timi ng char acte r i stics ( a pplies to al l p a rts 6,12 ) scl clock freu ency f scl 4 0 0 k h z t bu f bus free ti me between sta r t and stop t 1 1 . 3 s t hdsta hold time (repeated start ) t 2 after this period, the first clock pulse is ge nerated 0 . 6 s t low low period of scl clock t 3 1 . 3 s t high high period of scl clock t 4 0 . 6 5 0 s t su st a se tup tim e for start condition t 5 0 . 6 s t hddat data hold time t 6 0 . 9 s t su dat data setu p time t 7 0 . 1 s t f fall time of both sda and sc l signals t 8 0 . 3 s t r rise time of both sda and sc l signals t 9 0 . 3 s t su st o setup t i me for stop condition t 10 0 . 6 s 1 typicals represent average rea d ings at 25c and v dd = 5 v. 2 r e si st or po si t i on n o n l i n ea ri t y error r - in l i s t h e devi a t i o n fr om an ideal val u e meas ured betw een the maximum re si s t a n ce a n d t h e m i n im um resi st a n ce wi per po si t i on s. r - d n l m e a s ures t h e re la t i ve st ep ch a n ge fr om i d ea l b e t w een s u cces s i v e t a p posi t i on s. pa rt s a r e gua ra n t eed m o n o t o n i c. 3 v ab = v dd , w i p e r ( v w ) = n o c o n n e ct . 4 inl and dnl are m e as ured at v w with the rda c c o nf igured a s a p o tentiometer d i vid e r s imil ar to a vol t age output da c . v a = v dd and v b = 0 v. dnl s p ecif ic ation l imits of 1 l s b maximum are guaranteed monotonic operating cond itions . 5 res i s t or terminal s a , b, w ha ve no l imitations on pol a rity with res p ect to eac h other. 6 guarante e d by d e sign and no t s u bje c t to prod uctio n te s t . 7 different fr om op e r ating power supp ly, powe r supply fo r otp i s us ed on e- t i m e on ly. 8 different fr om op erating current, sup p ly curr ent for otp lasts approximately 400 ms fo r one-time ne eded only. 9 p diss i s ca lcula t e d fr om (i dd v dd ). cmo s l o gi c leve l i n put s resu lt in minimum power d i ss ipation. 10 ba n d wi dt h , n o i s e, a n d s e t t l i n g t i m e a r e depen d en t on t h e t e rm i n a l re si st a n ce va lu e ch o s en . th e low e st r va lue re su lt s i n t h e fa st est set t li n g t i m e a n d h i gh est band wid th. the highe s t r val u e res u lt in the minimum overal l power consu m ption. 11 all dynamic charac teristics use v dd = 5 v. 12 d i fferen t from set t li n g t i m e a f t e r fus e i s b l own . th e otp set t l i n g t i m e occur s on ce on ly. scl s da t 1 t 2 t 3 t 8 t 8 t 9 t 4 t 5 t 9 t 7 t 6 t 10 p ps 03437-0-024 f i g u re 3. int e r f ac e ti ming d i ag r a m r e v. pr c pa g e 4 of 20
ad5171 absolute maximum ratings table 2. p a r a m e t e r r a t i n g v dd to gnd C0.3, +7 v v a , v b , v w to g n d gnd, v dd maximum current i wb , i wa pulsed i wb continuous ( r wb 1 k?, a op en) 1 i wa continuous ( r wa 1 k?, b open) 1 20 ma 5 ma 5 ma digital inputs and output voltage to gnd 0 v, v dd operating tem p erature range C40c to +125c maximum junction temperature (t j max) 150c storage temperature C65c to +150c lead temperature (soldering, 10 sec) vapor phase (60 sec) infrared (15 sec) 300c 215c 220c t h ermal resista n ce 2 ja 2 3 0 c / w 1 m a ximum termina l current is b o un d e d by the maximum appl ied vol t age a c ross a n y t w o of t h e a, b, a n d w t e rm i n a ls a t a gi ven r e si st a n ce, t h e maximum current handling of the sw i t ches, and the maxi m um power di ssi pa t i on of t h e p a cka g e. v dd = 5 v . 2 pa cka g e p o wer d i s si pa t i on = (t j max C t a ) / ja s t r e s s es a b o v e t h os e lis t e d u n de r a b s o l u t e m a xi m u m r a t i n g s ma y c a us e p e r m a n en t dama ge t o t h e de vice . this is a s t r e s s ra t i n g onl y a nd f u n c t i o n al op era t io n o f t h e de v i ce a t t h es e o r 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 di ca te d in t h e op er a t io n a l 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 . 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. r e v. pr c | pa g e 5 of 20
ad5171 pin conf iguration and fu nctional descri ptions top view (not to scale) 8 7 6 5 1 2 3 4 w v dd gnd scl a b ad0 sda ad5171 03437- 0- 003 f i g u re 4. so t - 23- 8 ta ble 3. pi n f u nct i on d e s c ri pt i o ns pin no. mnemonic description 1 w wiper terminal w. gnd v w v dd . 2 v dd positive power s u pply. specified for operation fr om 2.7 v to 5.5 v. for otp programming, v dd needs to be a minimum of 6 v and 100 ma dri v ing capability. 3 g n d c o m m o n g r o u n d . 4 scl serial clo c k inp ut. requires pull-up resistor. 5 sda serial data inpu t/ output. requires pull-up re sis t or. 6 a d 0 i 2 c device addr ess bit. allows maximu m of two ad5171s to be addressed. 7 b resistor termin al b. gnd v b v dd . 8 a resistor terminal a. gnd v a v dd . r e v. pr c | pa g e 6 of 20
ad5171 typical perf orm ance cha r acte ristics ?0.10 ?0.08 ?0.06 ?0.04 ?0.02 0 0.02 0.04 0.06 0.08 0.10 rheostat mode inl (lsb) 32 24 81 6 0 4 04 8 5 66 4 code (decimal) 03437-0-004 ?4 0 c +25c +125c v dd = 5v f i gur e 5 . r - inl vs . co de vs . t e m p e r a t ur e ?0.10 ?0.08 ?0.06 ?0.04 ?0.02 0 0.02 0.04 0.06 0.08 0.10 rhe os tat mode dnl (ls b ) 32 24 81 6 0 4 04 85 66 4 code (decimal) 03437-0-005 ?4 0 c +25 c +125c v dd = 5v f i gur e 6 . r - dnl vs . c o de vs . t e m p e r a t ur e ?0.10 ?0.08 ?0.06 ?0.04 ?0.02 0 0.02 0.04 0.06 0.08 0.10 poten t iom eter m o d e in l ( l sb ) 32 24 81 6 0 4 04 85 66 4 code (decimal) 03437-0-006 ?40 c +25 c +125c v dd = 5v f i gur e 7 . inl vs . code vs . t e m p e r a t ur e ?0.10 ?0.08 ?0.06 ?0.04 ?0.02 0 0.02 0.04 0.06 0.08 0.10 poten t iom eter m o d e d n l ( l sb ) 32 24 81 6 0 4 04 85 66 4 code (decimal) 03437-0-007 ?40 c +25 c +125c v dd = 5v f i gur e 8 . dnl vs . c o de vs . t e m p e r a t ur e ?0.7 ?0.6 ?0.5 ?0.4 ?0.3 ?0.2 ?0.1 0 fse (lsb) ?40 ? 20 0 2 0 4 0 6 0 8 0 100 120 140 temperature ( c) 03437-0-008 v dd = 5v v dd = 3v f i gur e 9 . f u ll -sc a le er r o r 0 0.1 0.2 0.3 0.4 0.5 0.6 zse ( l sb) ? 4 0 ? 20 0 2 0 4 0 6 0 8 0 100 120 140 temperature ( c) 03437-0-009 v dd = 5v v dd = 3v f i gure 10. zero -s c a le e r r o r r e v. pr c | pa g e 7 of 20
ad5171 i dd supply current ( r ab /r ab )/ t vs . c o de ?5 0 5 10 15 20 25 r h e osta t mod e tempc o (ppm/ c ) 32 24 81 6 0 4 04 8 5 66 4 code (decimal) 03437- 0- 012 f i gure 1 3 . p o tentiom e ter m o de t e m p co ( v w /v w )/ t vs. c o de 100 1m 1k 10k 100k 10m frequency (hz) 0 6 ?6 ?12 ?18 ?24 ?30 ?36 ?54 ?42 ?48 ma gn itu d e (db ) 0x02 0x01 0x00 0x04 0x08 0x10 0x20 03437- 0- 013 f i gure 14. g a in vs. f r equ e nc y vs. c o d e , r ab = 5 k 100 1m 1k 10k 100k frequency (hz) 0 6 ?6 ?12 ?18 ?24 ?30 ?36 ?54 ?42 ?48 mag n itude (db) 0x3f 0x20 0x10 0x08 0x04 0x02 0x01 0x00 03437- 0- 001 f i gure 15. g a in vs. f r equ e nc y vs. c o d e , r ab = 10 k 100 1m 1k 10k 100k frequency (hz) 0 6 ?6 ?1 2 ?1 8 ?2 4 ?3 0 ?3 6 ?5 4 ?4 2 ?4 8 magnitude (db) 0x3f 0x20 0x10 0x08 0x04 0x02 0x01 0x00 03437- 0- 015 f i g u re 16. gain vs . f r equenc y vs . c o de , r ab = 50 r e v. pr c | pa g e 8 of 20
ad5171 frequency (hz) 100 1k 0 ?6 6 ?1 2 ?1 8 ?2 4 ?3 0 ?3 6 ?5 4 ?4 2 ?4 8 magnitude (db) 0x3f 0x20 0x10 0x08 0x04 0x02 0x01 0x00 1m 10k 100k 03437- 0- 016 f i gure 17. g a in vs. f r equ e nc y vs. c o d e , r ab = 10 0 k frequency (hz) 80 40 100 1m 1k 10k 100k p o we r s u p p l y re j e ction ratio ( ? db) 60 20 0 t a = 25c code = 0x20 v a = 2.5v, v b = 0v v dd = 5v dc 1.0v p-p ac v dd = 3v dc 0.6v p-p ac 03437-0-017 fi g u r e 1 8 . p s r r v s . fr e q u e n c y 10mv 5v 500ns v dd = 5.5v v a = 5.5v v b = gnd f clk = 100khz scl = 5v/div v w = 10mv/div 03437- 0- 018 f i gure 1 9 . di g i ta l f eedthro u g h vs . t i me v dd = 5.5v v a = 5.5v v b = gnd f clk = 400khz data 0x00 0x3f 5v 5v 5 s 03437-0-019 scl = 5v/div v w = 5v/div f i gure 2 0 . s e ttli n g t i m e v dd = 5.5v v a = 5.5v v b = gnd f clk = 100khz data 0x20 0x1f 5v 50mv 200ns v w = 50mv/div scl = 5v/div 03437-0-020 f i gur e 2 1 . m i dsc a le gl it c h ene r gy 5v 1v otp programmed at ms v dd = 5.5v v a = 5.5v r ab = 10k ? 5 s v dd = 5v/div v w = 1v/div 03437-0-021 f i gure 22. p o wer - u p s e ttling time , af ter f u ses blo w n r e v. pr c | pa g e 9 of 20
ad5171 the o re tical i wb _ m a x (ma) 0.01 1.00 0.10 10.00 32 24 81 6 0 4 04 85 66 4 code (decimal) 03437-0-022 r ab = 100k ? r ab = 50k ? r ab = 10k ? r ab = 5k ? v a = v b = open t a = 25c f i g u re 23. i wb _m ax v s . cod e r e v. pr c | pa g e 10 o f 20
ad5171 theory of operation the ad5171 al lo ws unlimi ted 6 - b i t ad j u s t m e n t s, excep t f o r o n e- t i me p r o g ra mma b l e, s e t- a nd-forget r e sist a n ce s e t t i n g. otp t e c h n o log y is a p r o v en cos t -ef f ec ti v e al t e r n a t i v e o v er eemem in on e-tim e m e m o r y p r og ra mmin g a p p l ic a t ion s . ad5171 em plo y s f u s e link t e chn o log y t o achie v e t h e mem o r y r e t e n t ion o f th e r e s i s t a n c e se t t in g fun c ti o n . i t c o m p ri se s si x da ta fu se s , whic h co n t r o l t h e ad d r es s deco d e r f o r p r ogra mmin g t h e rd a c , o n e us er m o de tes t f u s e fo r ch e c kin g s e t u p er r o r , a n d one p r ogra mmin g lo c k f u se f o r d i sa b l in g an y f u r t her p r ogra mmin g o n c e th e d a ta fu s e s a r e b l o w n . one-time programming (otp) p r io r t o o t p ac ti va tion, the ad5171 p r es ets t o mids cale d u r i n g p o w e r o n . af t e r th e wi p e r is set a t t h e d e sir e d p o si tio n , th e r e sis t a n c e can b e p e r m an en tl y s e t b y p r og ra mmin g the t b i t t o hig h alo n g wi th th e p r o p er co din g ( t a b le 7). the device con t r o l cir c ui t has tw o valida tio n b i ts, e1 a nd e0, th a t ca n be r e ad ba c k in th e r e ad m o d e f o r c h ecki n g t h e p r o g ra mmin g st a t us as sh o w n i n t a b l e 4. table 4. valida tion status e 1 e 0 s t a t u s 0 0 ready for progr a mming 0 1 test fuse not blown successfully. (for factory setup checking purpose o n ly. u s ers sh ould not see these com b i n ations.) 1 0 error. some fuses are not blown. try again. 1 1 successful. no further program ming is possible . w h en t h e otp t b i t is s e t, t h e i n t e r n al clo c k is ena b le d . th e p r og ra m wi l l a t tem p t t o b l o w a test f u s e . th e o p era t io n st o p s if t h i s f u s e i s not bl ow n prop e r ly . t h e v a l i d a t i on bit s e 1 a n d e 0 s h o w 01, an d t h e us ers s h o u ld ch eck the s e t u p . i f th e t e st f u s e is bl own su c c e ss f u l l y , t h e d a t a f u s e s wi l l b e p r o g r a mme d ne x t . t h e six da ta f u s e s wi l l be p r og ra mme d in six c l o c k c y c l es. th e o u t p u t o f th e f u s e s is co m p a r e d wi t h t h e co de st o r ed in the d a c r e g i s t er . i f they do n o t ma tc h, e1 a nd e0 = 10 is is s u ed as a er r o r a n d t h e op era t ion s t o p s. u s ers ma y r e t r y wi t h t h e s a m e co des. i f t h e o u tp u t an d sto r e d c o de m a tch, t h e p r o g r a mmin g lo c k f u s e wil l b e b l o w n s o tha t no f u r t h e r p r og ra mmin g is p o ssi b le. i n t h e m e an t i me, e1 a nd e0 w i l l issue 11 indic a t i n g t h e lo ck f u s e is b l o w n s u cces sf u l l y . a l l t h e f u s e l a t c h e s a r e enab le d a t p o w e r - o n and t h er efo r e t h e ou t p u t co r r es p o nds t o t h e st o r e d s e tt i n g f r om t h i s p o i n t on . f i g u re 2 4 show s a d e t a i l e d f u nc t i on a l bl o c k d i ag r a m . sda scl a w b fuses en dac reg. i 2 c interface comparator one-time program/test control block mux decoder fuse reg. 03437-0-025 f i g u re 24. d e t a iled f u nc t i on al bl ock d i ag r a m determining the var i able resistance and vol t a g e r h eos t at mo d e o p e r ation i f on ly t h e w - to - b or w - to - a te r m i n a l s are u s e d a s v a r i abl e re s i stor s , t h e u n u s e d te r m i n a l c a n b e op e n e d or shor te d w i t h w . this o p er a t io n i s ca l l e d rh e o st a t m o d e (f igur e 2 5 ). a w b a w b a w b 03437-0-050 f i g u re 25. r h e o s t at m o de conf ig ur at i o n the n o min a l r e sist a n ce ( r ab ) o f th e rd a c has 64 co n t ac t p o in ts access e d b y t h e wi p e r t e r m ina l , pl us t h e b t e r m ina l co n t ac t if r wb is co n s ider e d . t h e 6-b i t d a t a in t h e r d a c la t c h is deco de d t o s e le c t o n e o f t h e 64 s e t t in gs. a s s u min g tha t a 10 k? pa r t i s used , th e w i pe r s f i r s t co n n ect i o n s t a r t s a t t h e b t e rm in al f o r da t a 0x00. s u c h co nn ec tion yie l ds a minim u m o f 60 ? r e sis t a n c e be twe e n t e r m inals w an d b b e c a us e o f th e 60 ? wi p e r co n t ac t r e sis t a n ce . th e s e co nd co nn ec tion is the f i rs t t a p p o in t, which cor r es p o n d s t o 21 9 ? ( r wb = (1) r ab /63 + r w ) f o r da t a 0x01, a nd s o o n . e a c h ls b da t a val u e in cr eas e m o v e s t h e w i p e r u p t h e r e sis t o r ladder un t i l t h e l a s t t a p p o in t is r e ac h e d a t 1006 0 ? ((63) r ab /63 + r w ). f i gur e 26 s h o w s a s i m p l i f i ed di a g ra m o f th e eq ui val e n t rd a c ci r c ui t . th e g e n e ral eq ua ti o n d e t e r m i n in g r wb is w ab wb r r d d r + = 63 ) ( ( 1 ) w h er e: d is th e decimal eq ui valen t o f th e 6-b i t b i na r y co de . r ab is t h e e n d - to -end r e sist an c e . r w is t h e wi p e r r e sis t a n c e co n t r i b u t e d b y t h e on-r esis t a n c e o f th e in t e rn al swi t c h . r e v. pr c | pa g e 11 o f 20
ad5171 table 5. r wb vs . codes ; r ab = 1 0 k ? and the a ter m inal is ope n e d d (dec) r wb (?) output state 6 3 1 0 0 6 0 full-scale (r ab + r w ) 3 2 5 1 3 9 m i d s c a l e 1 2 1 9 1 l s b 0 60 zero-scale (wiper contact resistance) sin c e a f i ni t e w i p e r r e sis t a n c e of 60 ? is p r es en t in t h e zer o - s c ale con d i t ion, ca r e sh o u ld b e t a k e n t o limi t t h e c u r r en t f l o w b e tw e e n w and b in t h is st a t e t o a maxim u m p u ls e c u r r en t o f n o m o r e tha n 2 0 ma. o t her w is e , deg r ada t ion or p o s s i b le dest r u c t io n o f t h e i n ter n a l s w i t ch co n t ac t can o c c u r . si mi l a r to t h e me ch ani c a l p o te n t i o me te r , t h e re s i st a n c e of t h e rd a c bet w een th e wi per w a n d t e rm i n al a als o p r od uces a c o m p l e me n t ar y re s i st anc e r wa . w h en t h es e t e r m inals a r e us e d , t h e b t e r m i n a l c a n b e op e n e d or shor te d to w . s e tt i n g t h e re s i st anc e v a lu e f o r r wa st ar ts a t a max i m u m v a lu e of re s i st anc e a nd de cr e a s e s a s t h e d a t a lo ade d in t h e la tch i n cr e a s e s in va l u e. the ge n e ra l e q u a t i o n fo r t h is o p era t io n is w r ab r d d wa r + ? = table 6. r wa vs . codes ; r ab =1 0 k ? and b termi n al is ope n ed d (dec) r wa (?) output state 6 3 6 0 f u l l - s c a l e 3 2 4 9 8 0 m i d s c a l e 1 9 9 0 1 1 l s b 0 1 0 0 6 0 z e r o - s c a l e the typ i cal di s t r i b u t i on o f t h e resis t a n ce t o leran c e f r o m de vic e to de vice is p r o c ess lo t dep e nd en t, and i t is p o ssi b l e to h a ve 30% t o lera nce . d5 d4 d3 d2 d1 d0 rdac latch and decoder r s r s r s a w b 03437-0-026 f i gur e 2 6 . ad51 71 e q ui v a le nt rd a c cir c ui t potentiomet e r mod e op er a t ion i f al l t h r e e t e r m inals a r e s e d t h e op era t ion is al l e d t h e p o te n t i o me te r mo d e h e mo s t o m m on o n f i g r a t i o n i s t h e o l t a g e diider o p era t ion ig r e 2 i o i gre 2 p o tentiometer m o de c o nf ig r ation i g n o r i n g t h e ef fe t o f t h e wi p e r r e sis t a n e t h e t r a n sf er fn t i o n is sim p l = + + = d/63 w i th a r e la ti v e l y sm all err o r co n t ri b u t e d by t h e r w te r m s , and t h er ef o r e t h e t o lera n c e ef f e ct is a l m o s t ca ncel le d . a l t h o u g h t h e t h in f i lm s t ep r e sis t o r r s a n d cmos swi t ch es r e sis t a n ce r w ha v e v e r y dif f e r e n t t e m p er a t ur e coef f i cien ts, t h e ra t i o-m etr ic ad j u s t m e n t a l so r e d u ces t h e o v er a l l t e m p era t u r e coef f i cien t ef f e ct t o 5 p p m / o c, ex cep t a t lo w va l u e codes w h er e r w do mina tes. p o ten t io meter mode o p era t io n s i n c l ude o t h e rs s u c h as o p am p in p u t, f e e d b a c k r e sis t o r n etwo r ks, an d o t h e r v o l t age s c a l in g a p plica t io n s . a, w , an d b ter m in a l s can in fact b e in p u t o r o u t p u t termin a l s p r o v id e d t h a t |v ab |, |v wa |, and |v wb | do n o t ex ce e d v dd to gnd . esd protection dig i t a l in pu ts sd a and scl a r e p r o t e c te d w i t h a s e r i es in pu t r e sis t o r a n d p a ralle l e n e r es d s t r u ct ur es (f igur e 28). logic 340 ? r e v. pr c | pa g e 12 o f 20
ad5171 terminal voltage operating ra nge ther e a r e als o es d p r o t e c t i on dio d es b e twe e n v dd and t h e rd a c t e r m inals. th e v dd o f ad5171 th er ef o r e def i n e s th eir vo lt age b o u n d a r y c o nd i t i o ns , s e e f i g u re 2 9 . supply s i g n a l s p r es en t on t e r m inals a, b , an d w tha t exceed v dd wi l l b e cla m p e d b y t h e in ter n a l fo r w a r d- b i as e d dio d es a nd sh o u ld b e av o i d e d . gnd a w b v dd 03437-0-029 f i g u re 29. m a x i mu m t e r m i n a l v o lt ag es s e t by v dd power-up/ p ower-do w n sequen ces si m i l a r l y , b e c a u s e of t h e e s d prote c t i on d i o d e s , it i s i m p o r t an t to p o we r v dd f i rst b e f o re a p p l y i ng a n y vo lt age s to te r m i n a l s a , b , a nd w . o t h e r w is e, t h e dio d e wi l l b e fo r w a r d- b i as e d such t h a t v dd wi l l b e p o w e r e d uni n te n t iona l l y a n d ma y af fe c t t h e r e st o f t h e us ers cir c ui t s . th e ide a l p o wer - u p s e q u e n c e is in t h e f o l l ow i n g ord e r : g n d , v dd , d i g i t a l i n p u t s , a n d v a /v b /v w . t h e ord e r of p o we r i ng v a , v b , v w , a nd dig i t a l i n p u t s is n o t im p o r t an t as lon g as t h e y a r e p o w e r e d a f t e r v dd . s i m i l a r l y , v dd sh o u ld b e p o w e r e d do w n la st. power supply considerations t o m i n i m i z e th e pa c k a g e p i n co u n t , b o th th e o n e - t i m e p r og ra mmin g and n o r m al op era t in g v o l t a g es a r e a p plie d t o t h e sa m e v dd t e r m inal o f th e ad51 71. th e ad517 1 em p l o y s f u s e link tec h n o log y tha t r e q u ir es 6 v t o b l o w th e in t e r n al f u s e s t o achie ve a g i v e n s e t t i n g. o n t h e o t h e r hand , i t op era t es a t 2.7 v t o 5.5 v o n c e the p r og ra mmin g is co m p let e . s u c h d u al v o l t a g e r e q u ir es is ola t ion b e twe e n su p p lies. th e f u s e p r og ra mmin g s u p p l y (ei t h e r an o n -bo a r d r e gula t o r o r rac k -m o u n t p o w e r s u p p l y ) m u s t be ra t e d a t 6 v and b e a b le t o handle 400 m s and 100 ma o f tra n sien t c u r r en t f o r o n e-tim e p r og ra mmin g . o n ce p r o g r a mming is c o m p l e te, t h e 6 v su p p ly m u st b e re move d to al lo w n o r m al o p era t ion o f 2.7 v t o 5.5 v . f i gur e 30 s h o w s t h e s i m p l e s t im p l em en t a ti o n us i n g a j u m p e r . t h i s a p p r oa c h s a v e s o n e vol t a g e su pply , b u t dr a w s a ddi t i ona l c u r r en t and r e q u ir es ma n u a l co nf igu r a t io n. ad5171 v dd c2 0.1 f 5v connect j1 here for otp c1 1 f j1 r1 50k ? r2 250k ? 6v connect j1 here after otp 03437-0-030 f i g u re 30. p o wer s u p p ly r e qu ire m ent an al t e r n a t e a p p r o a c h in 3.5 v t o 5.5 v sys t em s adds a sig n al dio d e b e tw e e n t h e syst em s u p p ly a n d t h e o p t su p p l y fo r is ola t ion, as sh o w n in f i gur e 31. ad5171 v dd c2 0.1 f apply for otp only c1 10 f d1 3.5v?5.5v 6v 03437-0-031 f i g u re 31. is ol at i n g t h e 6 v opt sup p l y f r o m t h e 3. 5v t o 5. 5 v n o r m al o p er at ing sup p l y . the 6 v sup p l y m u s t be rem o ved once op t is c o mp lete . ad5171 v dd c2 0.1 f apply for otp only c1 10 f 10k ? 2.7v 6v p1 p2 r1 p1 = p2 = fdv302p, nds0610 03437-0-052 f i gure 3 2 . iso l a t ing the 6 v op t sup p l y fr om the 2 . 7 v norm al o p er a t i n g sup p ly . th e 6 v s u p p ly m u s t be r e m o ved on c e o p t is com p let e . f o r us ers w h o o p era t e t h e i r sys t em s a t 2.7 v , i t i s r e co mme n d e d t o use th e b i - d i r ecti o n al lo w - th r e s h o l d p - c h m o s f et s f o r th e s u p p lies is ol a t ion. a s sh o w n in f i gur e 32 as s u m e s t h e 2.7 v sys t em v o l t a g e i s a p plie d f i rs t b u t n o t t h e 6 v . th e g a t e s o f p1 a r e p2 a r e p u l l ed t o g r o u nd , whic h t u r n s on p1 a nd s u bs e- q u e n t l y p 2 . a s a r e s u l t , v dd o f a d 5171 be com e s 2.7 v min u s a f e w t e n t h s o f mv dr o p acr o s s p1 a nd p2. w h en th e ad5171 s e t t in g is fo und , t h e fac t o r y t e s t er a p plies t h e 6 v t o v dd and a l s o to t h e g a te s of p 1 and p 2 to t u r n t h e m of f. w h i l e t h e o t p co mman d is exe c u t in g a t this tim e t o p r og ra m ad5171, the 2.7 v s o ur ce is th er ef o r e p r o t ec ted . o n ce t h e otp is com p let e , th e t e s t er wi t h dra w s t h e 6 v , and ad5171 s e t t in g is p e r m an en tl y fi x e d . r e v. pr c | pa g e 13 o f 20
ad5171 contr o lling the ad5 171 ther e a r e tw o wa ys o f co n t r o l l in g th e ad5171. u s ers c a n ei t h er p r og ra m t h e de vices wi t h com p u t er s o f t w a r e o r ext e r n al i 2 c co n t r o l l ers. software prog ramming d u e t o t h e ad van t a g e o f t h e on e - t i m e p r og ra mma b le fe a t ur e , us ers ma y co n s ider p r og ra mmin g t h e de vic e i n t h e fac t o r y b e fo r e sh i p p i n g to end us ers. a d i o f fers a de vi ce p r o g r a mming s o f t wa r e , w h ich ca n b e im ple m e n t e d i n t h e fac t o r y o n pcs t h a t r u n w i n d o w s 9 5 t o xp p l a t fo r m s. a s a r e s u l t , ext e r n al co n t r o l - lers a r e n o t r e quir e d , w h ich sig n if ican t l y r e d u c e s de ve lo pm en t t i me . th e p r og ra m is an exe c u t a b le f i le t h a t do es n o t r e q u ir e a n y p r o g ra mmi n g la n g ua ges o r us er p r o g ra mmin g sk i l ls. i t is easy t o s e t u p and us e . f i gur e 33 s h o w s t h e s o f t wa r e in t e r f ace . the s o f t wa r e c a n b e do w n lo ade d f r o m ww w . a n a l o g . c o m . f i gure 33. a d 5 1 7 1 comp uter s o f t w a re inter f ace writ e the ad5171 s t ar ts a t mids cale af t e r p o w e r - u p p r io r t o th e o p t p r og ra mmin g . t o i n cr e m en t o r de cr em e n t t h e r e sis t a n c e , t h e us er ma y sim p ly m o v e t h e s c r o l l b a r o n t h e lef t . t o wr i t e an y s p e c if ic val u es, t h e us er sh o u ld us e t h e b i t p a t t e r n co n t r o l in t h e u p p e r s c r e en and p r es s t h e r u n b u t t on. th e fo r m a t o f wr i t in g da ta t o th e d e v i ce i s sh o w n i n t a b l e 7. o n ce th e d e si ra b l e set t i n g is fo un d , t h e us e r ma y p r es s t h e p r og ra m p e r m a n e n t b u t t o n t o b l o w t h e i n t e r n al f u s e links fo r p e r m a n e n t s e t t i n g. th e us er ma y al so se t th e p r ogra m m i n g b i t pa t t e rn in th e u p pe r sc r e e n a n d p r e s s th e r u n b u t t o n t o a c h i ev e th e sa m e r e s u l t . read t o re a d t h e v a l i d a t i on bit s a n d d a t a out f r om t h e d e v i c e , t h e us er ma y sim p ly p r es s t h e re ad b u t t o n . th e us e r ma y als o s e t t h e b i t p a t t er n i n t h e u p p e r s c r e en an d p r es s t h e r u n b u t t on. t h e f o r m a t of re a d i n g d a t a out f r om t h e d e v i c e i s show n i n ta b l e 8 . t o a p pl y t h e de vice p r og ra mmi n g s o f t w a r e in t h e fac t o r y , us ers n e e d t o m o dif y a p a ral l e l p o r t c a b l e an d conf igur e p i n s 2, 3, 15, a nd 25 fo r s d a _ wr i t e, scl, s d a_r e ad , and d g nd , r e sp e c t i vely fo r th e co n t r o l sig n als (f igur e 34). u s ers sh o u ld als o la yo u t the pcb o f th e ad5 171 wi t h scl and s d a p a ds, as s h o w n in f i gur e 35, s u c h tha t p o g o p i n s c a n be ins e r t ed fo r th e fac t o r y p r o g ra mmin g . 13 25 12 24 11 23 10 22 9 21 8 20 7 19 6 18 5 17 4 16 3 15 2 14 1 scl r3 100 ? r2 100 ? r1 100 ? sda read write 03437-0-033 f i g u re 34. p a r a l l e l p o r t con n ec t i on. p i n 2 = sda _ w r it e , p i n 3 = scl, p i n 15 = s d a _ r e ad , and pin 2 5 = dgn d w v dd dgnd scl a b ad0 sda 03437-0-034 f i g u re 35. r e c o m m e nded a d 51 7 1 pc b lay o ut. the scl and sd a pads allo w pogo p i ns to b e i n ser t ed so that si g n a l s c a n b e co m m un ic ated th rou g h th e pa r a ll el p o r t f o r pr o g r a mm ing (fi g ure 34 ). table 7. s d a write mode bit format s 0 1 0 1 1 0 a d 0 0 a t x x x x x x x a x x d 5 d 4 d 3 d 2 d 1 d 0 a p slave address byte instruction byte data byte table 8. s d a r e ad mode bit format s 0 1 0 1 1 0 a d 0 1 a e 1 e 0 d 5 d 4 d 3 d 2 d 1 d 0 a p slave address byte data byte r e v. pr c | pa g e 14 o f 20
ad5171 ta ble 9. s d a b i t s defi ni t i ons a nd des c ri pt i o ns b i t d e s c r i p t i o n b i t d e s c r i p t i o n s p start condition. stop condition. d5, d4, d3, d2, d1, d0 data bits. a a c k n o w l e d g e . ad0 i 2 c device addr ess bit. allows maximum of two ad5171s to be addressed. x d o n t c a r e . t otp programming bit. logic 1 programs wi per positio n perma n ently. e1, e0 0, 0 0, 1 1, 0 1, 1 ot p validation bits. ready to progra m. t e st fuse not blown succes s full y. (for factory setup checking purpose only. u s ers sh ould not see these com b i n ations). fatal error. try again. programmed successful ly. no fu rther ad justments possi ble. i 2 c controller programming w r i t e bi t pa t t e r n i l l u s t r a t i on s sda frame 1 slave address bte frame 2 instruction bte frame 1 data bte scl ac. b ad5171 ac. b ad5171 ac. b ad5171 stop b master s tart b master 0 1 1 0 11 0 ad0 r/w 0 d 5 d4 d3 d2 d1 d0 9 1 9 1 9 03437-0-035 f i g u re 36. w r it ing t o t h e r d a c r e g i s t e r sda frame 1 slave address bte frame 2 instruction bte frame 1 data bte scl ac. b ad5171 ac. b ad5171 ac. b ad5171 stop b master start b master 0 1 1 0 11 0 ad0 r/w 1 d 5 d 4d 3 d 2d 1 d0 9 1 9 1 9 03437-0-036 f i gure 3 7 . a c ti v a ti ng o n e- ti me p r o g r a m m i n g r e a d bi t pa tt e r n i l l u s t r a t i on sda fram 1 slav addrss bt fram 2 rdac ristr scl ac. b ad5171 no ac. b mastr stop b mastr s tart b mastr 0 1 1 0 11 0 ad0 1 0 d5 d4 d3 d2 d1 d0 91 9 rw 034370037 f i gure 3 8 . rea d i n g da t a from rd a c r e gi st er f o r us ers wh o p r ef er t o us e ext e r n al co n t r o l l ers, th e ad5171 ca n be con t r o l l ed via a n i 2 c com p a t i b le s e r i al b u s an d is co nnec t e d t o this b u s as s l a v e device . ref e r r i n g t o f i gur e 36, f i gur e 37, a nd f i gur e 38, th e 2-wir e i 2 c s e r i al b u s p r o t o c ol op e r a t e s a s f o l l o w s 1. the mas t er ini t i a t e s da t a t r an sfer b y es t a b l is hing a s t a r t co ndi t i on, w h ich is w h e n s d a f r o m hig h -t o-lo w w h i l e s c l is hig h (f igur e 36 a nd f i gur e 3 7 ). th e fol l o w ing b y t e is t h e sla v e ad dr ess b y t e , w h ich co n s ists o f t h e 6 ms bs as a sl a v e addr es s def i n e d as 010110. the n e xt b i t is ad0, whic h is a n i 2 c de vic e addres s b i t. d e p e n d i n g o n t h e st a t es o f t h eir ad0 b i ts, tw o ad5171 can b e addr es s e d o n t h e s a me b u s (f igur e 39). th e las t l s b is t h e r/ w b i t, w h ich de t e r m in e s w h e t h e r d a t a w i l l b e re a d f r om or w r i tte n to t h e sl a v e de vice. the s l a v e w h os e addr es s co r r esp o n d s t o t h e t r an smi t t e d addr ess r e sp onds b y p u l l in g t h e s d a l i n e go es lo w d u r i n g th e 9 th clo c k p u ls e (t his is t e r m e d t h e a c k n o w le dg e b i t). a t r e v. pr c | pa g e 15 o f 20
ad5171 th i s s t a g e , all o t h e r devi ce s o n t h e b u s r e m a in idle wh ile t h e s e l e c t e d d e v i c e w a i t s for da t a to b e w r it te n to or re a d f r om it s s e r i a l re g i s t e r . 2. the wr i t e o p era t io n co n t a i n s on e m o r e i n s t r u c t io n b y t e t h a n t h e r e ad op era t ion. th e i n s t r u c t io n b y t e i n t h e wr i t e m o de fol l o w s t h e s l a v e addr es s b y t e . th e ms b o f t h e in st r u c t io n b y t e la b e le d t is t h e o n e - t i m e p r og ra mmi n g b i t. af t e r ack n o w le dg ing t h e inst r u c t io n b y t e , t h e last b y t e in t h e wr i t e m o de is t h e d a t a b y t e . d a t a is t r a n s m i t t e d o v er th e se r i al b u s in seq u en c e s o f n i n e c l oc k p u l s e s (e i g h t da ta bi t s f o l l ow e d by a n a c k n ow l e d g e bi t ) . t h e t r a n s i t i on s o n t h e sd a li ne m u st o c c u r d u r i ng t h e lo w p e r i o d o f scl an d re m a i n s t abl e du r i ng t h e h i g h p e r i o d of s c l ( f i g u r e 3 6 ) . 3. i n t h e r e a d m o de , th e da ta b y t e f o llo w s i m m e dia t e l y a f t e r t h e ack n o w le dg m e n t o f t h e s l a v e addr es s b y te . d a t a is tra n smi t t e d o v er th e s e r i al b u s in s e q u e n ces o f nin e c l o c k p u ls es (s lig h t di f f er en ce w i t h t h e wr i t e m o de; t h er e a r e eig h t da t a b i ts fol l o w e d b y a n o a c k n o w le dge b i t). s i m i la r l y , th e tra n si ti o n s o n t h e s d a lin e m u s t occur d u ri n g th e l o w pe ri od o f s c l a n d r e m a in s t a b l e d u ri n g th e hig h p e r i o d o f scl (f igur e 38). 4. w h en al l da ta b i ts ha v e been r e ad o r wr i t t e n, a s t o p co ndi t i on is est a b l ish e d b y t h e mast er . a st o p c o n d i t ion is def i n e d as a lo w-to -hig h t r a n s i t i o n o n t h e sd a l i ne w h i l e scl is hig h . i n t h e wr i t e m o de , t h e mas t er wi l l pu l l t h e sd a l i n e h i g h du r i ng t h e 1 0 th cl o c k p u ls e t o es t a b l is h a s t o p co ndi t i on (f igu r e 36 a nd f i gur e 37). i n t h e r e ad m o de, t h e mas t er wi l l iss u e a n o a c k n o w le dg e fo r t h e 9 th cl o c k p u l s e, i . e . , t h e s d a l i n e r e m a i n s h i g h . t h e m a s t e r w i l l t h e n b r i n g th e s d a line lo w bef o r e t h e 10 th cl o c k p u l s e, w h ich go es hig h t o est a b l ish a st o p con d i t i o n (f igur e 38). a r e p e a t e d wr i t e f u n c t i on g i v e s t h e us er f l exi b il i t y t o u p da te t h e rd a c o u t p u t a n u m b er o f tim e s, excep t a f t e r p e r m a n en t p r o g r a mmin g , a ddr essing, a nd i n st r u c t in g t h e p a r t o n ly o n ce. dur i n g th e wr i t e c y c l e , eac h da t a b y t e wil l u p da t e the rd a c o u t p u t . f o r exa m p l e , a f t e r t h e rd a c has ac k n o w le dg e d i t s sla v e addr ess and inst r u c t io n b y tes, t h e r d a c o u t p ut wi l l up da te af te r t h e s e t w o b y te s . i f anot he r b y te i s w r it te n t o t h e r d a c w h i l e i t is s t i l l addr es s e d t o a sp e c if ic s l a v e de v i ce w i t h t h e s a me in st r u c t io n, t h is b y t e w i l l u p d a te t h e o u t p u t o f t h e s e le c t e d sla v e de vice . i f dif f er en t ins t r u c t io n s a r e n e e d e d , t h e wr i t e mo de has to b e st a r te d w i t h a ne w sla v e ad dr ess, in st r u c t io n, a nd d a t a b y t e s. s i mila rl y , a r e p e a t e d r e ad f u n c tion o f th e rd a c is als o allo w e d . contr o lling two de vices o n o n e bus f i gur e 39 s h o w s tw o ad5171 de vices on the s a m e s e r i al b u s. e a ch has a dif f er en t s l a v e addr e s s since t h e s t a t e o f e a ch a d 0 p i n is dif f er en t. this al lo ws eac h de vic e t o be op era t e d indep e n d en t l y . the mas t er de v i ce o u t p u t b u s lin e dr i v ers a r e o p e n -d ra in p u ll- d o w n s i n a full y i 2 c co m p a t i b l e in ter f ace . master sda scl ad0 ad5171 sda scl ad0 ad5171 sda scl 5v rp rp 5v 03437-0-038 f i gur e 3 9 . t w o ad51 71 de vic e s o n one bus r e v. pr c | pa g e 16 o f 20
ad5171 appli c ations programmable voltage reference ( d ac) i t i s c o m m on to b u f f e r t h e output of t h e d i g i t a l p o te n t i o me te r as a d a c un less t h e lo ad is m u ch la rger t h a n r wb . th e b u f f er s e r v es t h e p u r p os e o f im p e dance co n v ersio n as w e l l as d e l i v e ri n g hi g h er curr e n t , wh i c h m a y b e n eed e d . gnd v in v out 1u 1 5v 2 3 v 0 ad8601 5v a w b ad1582 adr03 a1 ad5171 u2 03437-0-039 f i g u re 40. p r og r a m m ab le v o lt ag e r e f e r e nc e ( d a c ) gain c o ntrol compe n sation th e di g i t a l p o te n t i o me te rs are c o mmon ly u s e d i n g a i n c o n t rol s (f igur e 41) o r sen s o r t r a n sim p e d an c e am plif ie r sig n a l co ndi t i onin g a pplica t ion s . t o a v o i d ga i n p e a k ing o r in w o rst- c a se osc i lla ti o n d u e t o s t e p r e s p o n se , a c o m p en sa ti o n ca pa c i t o r i s ne e d e d . i n ge ne r a l, c 2 i n t h e r a nge of a fe w pi c o f a r a d s to no m o r e t h an a fe w t e n t h s o f a picofa rad is ade q u a te fo r t h e co m p en s a t i o n . u1 c2 4.7pf a b w r2 100k ? v o v i r1 47k ? 03437-0-040 f i g u re 41. t y pic a l n o ni nve r t i ng g a in a m pl if ie r programmable voltage source with booste d o u tput fo r ap p l i c at i o n s t h at r e q u i r e h i g h c u r r e n t a d j u s t m e nt , s u c h a s a las e r dio d e dr i v er o r t u na b l e la s e r , a b o o s te d volt a g e s o ur ce ca n b e con s ider e d ( f igur e 42). +v w signal c c r bias ld v in a b v out u1 a d5171 u3 2n7002 ad8601 u2 ?v i l 03437-0-041 f i g u re 42. p r og r a m m ab le bo os te r v o lt ag e s o u r c e i n th i s ci r c ui t , th e in v e r t i n g i n p u t o f th e o p a m p f o r c e s th e v ou t t o b e e q ual t o t h e w i p e r v o l t a g e s e t b y t h e dig i t a l p o t e n t iom e ter . the lo ad c u r r en t is t h e n de li v e re d b y t h e s u p p ly vi a t h e n-c h fet n 1 . n 1 p o w e r h a nd l i ng m u st b e a d e q u a te t o d i ss i p a t e (v i ? v o ) i l p o w e r . this cir c u i t can s o ur ce a maxim u m o f 100 ma wi t h a 5 v s u p p l y . f o r p r ecisio n a p p l ic a t io n s , a v o l t a g e r e f e r e n c e s u c h as ad r421, adr03, o r ad r370 ca n be a p p l ie d a t t h e a te r m i n a l of t h e di g i t a l p o te n t i o me te r . level shifting for different vol t age operat ion w h en us ers n e e d t o in t e r f ace a 2.5 v co n t r o l l er wi t h ad5171, a p r o p er v o l t a g e l e v e l s h if t m u s t b e e m plo y e d s o t h a t t h e dig i t a l p o te n t i o me te r c a n b e re a d f r om or w r i tte n to t h e c o n t rol l e r ; f i g u re 4 3 show s one of t h e i m pl e m e n t a t i ons . m 1 an d m 2 shou l d b e l o w t h re shol d n-c h p o we r mo s f e t s , su ch as fd v301 n. 2.5v controller 2.7v? 5.5v ad5171 rp rp rp rp v dd1 = 2.5v v dd2 = 5v g g s d m1 s d m2 sda1 scl1 sda2 scl2 03437- 0- 042 f i gure 43. l e vel s h i f ting for d i fferent v o ltag e o p e r at ion resistance scaling the ad5171 o f f e rs 5 k ? , 10 k ? , 50 k ? , an d 100 k ? nom i n a l r e sis t a n ces. f o r us ers wh o n e e d t o o p timize t h e r e s o l u tio n wi t h an ar b i t r ar y f u l l - r ange re s i st a n c e , t h e fol l ow i n g te ch n i qu e s c a n b e u s e d . by p a r a l l el i n g a d i s c re t e re s i stor ( f i g u r e 4 4 ) a prop or t i on tely l o we r vo lt age a p p e ar s a t te r m i n a l a to b , w h i c h is a p plicab le to o n ly t h e vol t a g e di v i der m o de. this t r a n sla t es i n t o a f i n e r deg r e e o f p r e c isio n b e ca us e t h e st ep size a t ter m ina l w wi l l b e sma l ler . th e vol t a g e c a n b e fo und as dd a b ab w v d r r r r r d v + = 64 2 || 3 ) 2 || ( ) ( ( 5 ) r1 r2 b a v dd r3 w 03437-0-043 f i gure 44. l o w e rin g the n o m i n a l r e s i s t anc e r e v. pr c | pa g e 17 o f 20
ad5171 f o r l o g t a p e r adj u st me n t , su ch a s vol u me c o n t rol, f i g u re 4 5 show s a n ot he r w a y of re s i st anc e s c a l i n g to a c h i e v e t h e l o g t a p e r fun c ti o n . i n th i s ci r c ui t , th e sm a l le r th e r 2 w i t h r e s p ect t o r ab , t h e m o r e li k e t h e ps eudo log t a p e r cha r ac t e r i s t ic i t b e ha v e s. the wi p e r v o l t a g e is sim p ly i wb wa wb w v r r r r r d v + = 2 || ) 2 || ( ) ( ( 6 ) v i r1 b a r2 v o w 03437-0-044 f i gur e 4 5 . resi st or sc ali n g wi th l o g a d justm e nt cha r a c ter i stics resolution enhance m ent the r e s o l u t i o n ca n b e do ub le d in t h e p o ten t iom e ter mo de o f o p era t ion b y usin g t h r e e dig i t a l p o t e n t iom e t e rs. b o r r o w e d f r o m adi s p a te n t e d rd a c s e g m en t a t i o n te ch niq u e, us ers ca n con- f i gur e thr e e ad5171 (f igur e 46) t o do u b le t h e r e s o l u tio n . f i rs t, u 3 m u s t be p a ra l l e l wi th a dis c r e t e r e sis t o r r p , w h ich is ch os en t o be e q ual t o a s t ep r e sis t an ce ( r p = r ab /64). o n e ca n s e e tha t ad j u st ing u1 and u2 t o get h er fo r m s t h e co a r s e 6 - b i t a d j u s t m e n t a n d t h a t ad j u s t in g u3 alo n e f o r m s t h e f i n e r 6-b i t ad j u st m e n t . a s a r e s u l t , t h e ef fe c t iv e res o l u t i on b e com e s 1 2 - b i t . u1 a1 b1 w1 u2 a2 b2 w3 w2 u3 a3 b3 r p coarse a djustmen t fine adjustment 03437-0-045 f i g u re 46. d o ub lin g t h e r e s o lut i on rdac circuit simulation model the i n t e r n al p a rasi t i c c a p a ci t a nces a nd t h e ext e r n al ca p a ci t i v e lo ads do mina t e t h e ac cha r ac t e r i st ics o f t h e dig i t a l p o t e n t io- m e ters. c o nf igur e d as a p o te n t i o m e ter divider , t h e C3 db ba ndwid th o f the ad5171 (5 k ? r e sis t o r ) m e as u r es 1.5 mh z a t half s c ale . f i gur e 14 t o f i gur e 17 p r o v ide the larg e sig n al b o d e pl ot ch ar a c te r i st i c s of t h e f o u r av ai l a bl e re s i stor ve r s i o ns 5 k ? 10 k ? , 50 k ? , and 100 k ? . a p a rasi tic sim u l a tion m o de l is s h own in f i gur e 47. l i s t in g 1 p r o v ides a macr o m o de l n e t list f o r th e 10 k ? de vice. 55pf c a 25pf c b 25pf a b rdac 10k ? w c w 03437-0-046 f i g u re 47. ci r c u i t si m u lat i on m o d e l f o r r d a c = 10 k ? li s t i n g 1 . m a c r o m o d e l n e t li s t f o r r d a c .param d=64, rdac=10e3 * .subckt dpot (a,w,b) * ca a 0 25e-12 rwa a w {(1-d/64)*rdac+60} cw w 0 55e-12 rwb w b {d/64*rdac+60} cb b 0 25e-12 * .ends dpot r e v. pr c | pa g e 18 o f 20
ad5171 ad5171 evaluation b o ard 8 7 6 5 4 3 2 1 j1 w v dd gnd scl a b ad0 sda out1 out1 +in1 v+ v? ? in2 +in2 out2 ?i n 1 jp8 jp7 jp4 jp6 c8 0.1 f c9 10 f v ee u3a cp4 cp2 jp5 jp3 c6 0.1 f c7 10 f 1 2 3 4 8 5 6 7 ?in1 cp3 cp1 v in 1 ad5170 ad5171/ad5273 agnd v ref adr03 2 3 5 4 c1 10 f c2 0.1 f r1 10k ? r2 10k ? scl sda c3 0.1 f u1 1 2 3 4 8 7 6 5 1 2 3 4 8 7 6 5 u2 c4 0.1 f u4 temp gnd v in trim v out c5 0.1 f jp1 jp2 a w b cp6 cp7 u3b v dd v dd w v dd gnd scl a b ad0 sda v dd v dd v cc cp5 03437-0-047 f i g u re 48. a d 5 1 7 1 ev aluat i on bo ar d s c he mat i c the ad5171 e v al ua t i o n bo a r d co m e s wi th a d u al o p a m p ad822 an d a 2. 5 v r e f e r e n c e ad r03. u s ers c a n co nf igur e man y o t h e r b u i l din g blo c k cir c ui ts wi t h min i m u m com p on e n ts n e e d e d . f i gur e 49 s h o w s on e o f t h e exam ples. th er e is s p ac e a v a i la b l e on t h e b o a r d t h a t us ers ca n b u i l d addi t i o n al cir c ui ts f o r f u r t h e r eval ua tio n s, see f i gur e 50. a b w v o v ref a b w v dd cp2 u2 jp1 jp2 jp4 jp3 jp7 4 u3a 1 out1 v+ v? ad822 2 3 11 v ref 03437-0-048 f i g u re 49. p r og r a m m ab le v o lt ag e r e f e r e nc e f i g u re 50. a d 5 1 7 1 ev aluat i on bo ar d r e v. pr c | pa g e 19 o f 20
ad5171 outline dimensions 13 5 6 2 8 4 7 2. 90 bs c pin 1 1. 60 bs c 1. 95 bs c 0. 65 bs c 0. 38 0. 22 0. 15 m a x 1. 30 1. 15 0. 90 sea t i n g pl a n e 1. 45 m a x 0. 22 0. 08 0. 60 0. 45 0. 30 8 4 0 2. 80 bs c compliant to jedec standards mo-178ba f i g u re 51. 8-l e ad s m a l l o u t l i n e t r ans i s t or p a ck ag e [so t - 23] (r j- 8) di me nsio ns sho w n i n mi ll im e t e r s ordering guide m o d e l r ab (k?) package code package descri pt ion full container quantity branding ad5171brj5-rl 7 5 r j - 8 s o t - 2 3 - 8 3 0 0 0 d 1 2 a d 5 1 7 1 b r j 1 0 - r l 7 1 0 r j - 8 s o t - 2 3 - 8 3 0 0 0 d 1 3 a d 5 1 7 1 b r j 5 0 - r l 7 5 0 r j - 8 s o t - 2 3 - 8 3 0 0 0 d 1 4 a d 5 1 7 1 b r j 1 0 0 - r e e l 7 1 0 0 r j - 8 s o t - 2 3 - 8 3 0 0 0 d 1 5 a d 5 1 7 1 b r j 5 - r 2 5 r j - 8 s o t - 2 3 - 8 3 0 0 0 d 1 2 a d 5 1 7 1 b r j 1 0 - r 2 1 0 r j - 8 s o t - 2 3 - 8 3 0 0 0 d 1 3 a d 5 1 7 1 b r j 5 0 - r 2 5 0 r j - 8 s o t - 2 3 - 8 3 0 0 0 d 1 4 a d 5 1 7 1 b r j 1 0 0 - r 2 1 0 0 r j - 8 s o t - 2 3 - 8 3 0 0 0 d 1 5 a d 5 1 7 1 e v a l * 1 0 1 * th e eva l ua t i on bo a r d i s sh i pped wi t h t h r ee pi ece s o f 10 k ? pa rt s. u s er s sh ou ld or der ext r a sa m p les or di ff eren t re si s t a n ce op tio n s if nee d ed . purch a se of li c e n s e d i 2 c compon en t s o f an alog d e vices or on e of it s s u bl ice n se d as so ciate d co m p a n i e s co n v eys a li cen s e f o r t h e purch a ser un der t h e ph i l i p s i 2 c p a tent rights to us e the s e co mpo n e nts in a n i 2 c sy st em , pro v id e d that the sys t e m co nfo r ms to the i 2 c stand a rd sp ecif ication as defi n e d by ph i l i p s. ? 2003 analo g de vices, inc. all rights reserve d . tra d em arks and registered tra d ema r ks are the prop erty of their respective owners . c03437-0-9/03(pr c) r e v. pr c | pa g e 20 o f 20

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