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2.5 v/3.0 v high precision reference ad780 rev. e 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 pin programmable 2.5 v or 3. 0 v output ultralow drift: 3 ppm/c max high accuracy: 2.5 v or 3.0 v 1 mv max low noise: 100 nv/ hz noise reduction capability low quiescent current: 1 ma max output trim ca pability plug-in upgrad e for present re ferences temperature o u tput pin series or shunt mode operation (2.5 v, 3.0 v ) func tio n a l block di agram 00841-001 r16 r10 +v in r4 r5 q6 q7 r11 r14 r13 r15 nc v out trim gnd o/p select 2.5v ? nc 3.0v ? gnd t emp nc nc = no connect ad780 7 2 1 3 48 5 6 fi g u r e 1 . produc t d e scripti o n the ad780 is an u l trahig h p r ec isio n ban d g a p r e f e r e n c e v o l t a g e tha t p r o v ides a 2.5 v o r 3.0 v o u t p u t f r o m in p u ts betw een 4.0 v a nd 36 v . l o w i n i t ia l er r o r a n d tem p er a t ur e dr i f t co m b i n e d w i t h lo w o u t p u t n o is e a nd t h e ab i l i t y t o dr i v e an y val u e o f ca p a c i tan c e ma k e t h e ad780 t h e ideal ch o i ce fo r enha n c in g t h e p e r f o r ma n c e o f hig h r e s o l u t i on ad cs and d a c s , a nd fo r a n y gen e ra l - p u r p os e p r e c isio n r e fer e n c e a p pli c a t ion. a uni q ue lo w h e adr o o m desig n facili ta t e s a 3. 0 v o u t p u t f r o m a 5.0 v 10% in p u t, p r o v idin g a 20% bo os t t o th e d y na mic ra n g e o f a n ad c ove r p e r f o r m a nc e w i t h e x i s t i ng 2 . 5 v re fe re nc e s . the ad780 can be us e d t o s o ur ce o r sink u p t o 10 ma, an d can be us e d in s e r i es o r s h un t mo de, th us al lo win g p o si ti v e o r ne g a t i v e output vo lt age s w i t h out e x te r n a l c o m p one n t s . t h i s m a ke s it s u it a b l e f o r v i r t u a l l y a n y h i g h p e r f or m a n c e re f e re n c e a p p l ic a t ion. u n l i k e s o m e com p etin g r e f e r e n c es, th e ad780 has n o r e g i o n o f p o s s i b le in s t ab il i t y . the p a r t is s t a b le un der al l lo ad co ndi tion s w h en a 1 f b y p a s s ca p a c i t o r is us e d o n t h e su p p l y . a t e m p era t ur e o u t p u t p i n o n t h e ad780 p r o v ides a n o u t p u t v o l t a g e t h a t va r i es lin e a r l y wi t h t e m p era t ur e , al lo win g t h e p a r t t o b e conf igur e d as a t e m p era t ur e t r a n s d ucer w h i l e p r o v i d in g a s t a b le 2.5 v o r 3 . 0 v o u t p u t . the ad780 is a p i n com p a t i b le p e r f o r ma n c e u p g r ade f o r th e l t 1019(a)C2.5 a nd t h e ad680. the l a t t e r is ta rg et ed t o wa r d l o w p o w e r ap p l i c at i o n s . the ad780 is a v a i lab l e in thr e e g r ades in p d ip a nd so i c p a c k a g es. th e ad780an, ad78 0ar , ad780bn, ad780br , an d ad780cr a r e sp ecif ied f o r o p era t io n f r o m ?40 c t o +85c. product highlights 1. the ad780 p r o v ides a p i n p r og ra mma b l e 2.5 v o r 3.0 v o u t p u t f r o m a 4 v t o 36 v in p u t. 2. l a s e r t r imm i n g o f b o t h in i t ia l a c c u rac y a n d te m p er a t ur e co ef f i cien ts r e su l t s in lo w er r o r s o v er t e m p era t ur e wi t h o u t t h e us e o f ext e r n al co m p onen t s . th e ad780 bn has a maxim u m va r i a t io n o f 0.9 mv f r o m ?40c t o +85c. 3. fo r ap p l i c at i o n s t h at r e q u i r e e v e n h i g h e r a c c u r a c y , a n opt i on a l f i ne - t r i m c o n n e c t i o n i s prov i d e d . 4. the ad780 n o is e is extr eme l y lo w , typ i cal l y 4 mv p-p f r o m 0.1 h z t o 10 h z a nd a wideban d s p ec tral n o is e den s i t y o f typ i cal l y 100 nv/ hz . this ca n b e f u r t h e r r e d u ce d , if de s i re d, b y u s i n g t w o e x te r n a l c a p a c i tors . 5. the t e m p er a t ure o u t p ut p i n ena b les t h e ad78 0 t o b e co nf igur e d as a t e m p era t ur e t r an s d ucer w h i l e pr o v idin g a st abl e output re f e re nc e.
ad780 rev. e | page 2 of 12 able of contents .................................................... 3 th supply current over temperature .............................................8 o evision history ed from rev. d to rev. e .... universal ..................2 ....................10 t specifications ................................. absolute maximum ratings ............................................................ 4 notes ............................................................................................... 4 esd caution .................................................................................. 4 eory of operation ........................................................................ 5 applying the ad780 ......................................................................... 6 noise performance ....................................................................... 6 noise comparison ........................................................................ 7 temperature performance ........................................................... 7 temperature output pin ............................................................. 7 temperature transducer circuit ................................................ 8 tur n-on ti me ...............................................................................8 dynamic performance ..................................................................8 line regulation ..............................................................................9 precision reference for high resolution 5 v data converters ..........................................................................................................9 4.5 v reference from 5 v supply ............................................. 10 negative (C2.5 v) reference ..................................................... 10 utline dimensions ....................................................................... 11 ordering guide ............................................................................... 12 r 5/04data sheet chang updated format.............................................................. changes to temperature transducer circuit section ...................8 changes to ordering guide ...........................................................12 1/04data sheet changed from rev. c to rev. d. changes to specifications...................................... updated ordering guide.........................................................3 updated outline dimensions .............................................10 5/02data sheet changed from rev. b to rev. c. updates to packages ........................................................
ad780 rev. e | page 3 of 12 specifications t a = 25c, v in = 5 v, unless otherwise noted. table 1. ad780an/ad780ar ad780cr ad780bn/ad780br parameter min typ max min typ max min typ max unit output voltage 2.5 v out 2.495 2.505 2.4985 2.5015 2.499 2.501 v 3.0 v out 2.995 3.005 2.9950 3.0050 2.999 3.001 v output voltage drift 1 ?40c to +85c 7 7 3 ppm/c ?55c to +125c 20 20 ppm/c line regulation 2.5 v output, 4 v +v in 36 v, t min to t max 10 10 10 v/v 3.0 v output, 4.5 v +v in 36 v, t min to t max 10 10 10 v/v load regulation, series mode sourcing 0 ma < i out < 10 ma 50 50 50 v/ma t min to t max 75 75 75 v/ma sinking ?10 ma < i out < 0 ma 75 75 75 v/ma ?40c to +85c 75 75 75 v/ma ?55c to +125c 150 150 150 v/ma load regulation, shunt mode i < i shunt < 10 ma 75 75 75 v/ma quiescent current, 2.5 v series mode 2 C40c to +85c 0.75 1.0 0.75 1.0 0.75 1.0 ma ?55c to +125c 0.8 1.3 0.8 1.3 0.8 1.3 ma minimum shunt current 0.7 1.0 0.7 1.0 0.7 1.0 ma output noise 0.1 hz to 10 hz 4 4 4 v p-p spectral density, 100 hz 100 100 100 nv/ hz long-term stability 3 20 20 20 ppm/1000 hr trim range 4.0 4.0 4.0 % temperature pin voltage output @ 25c 500 560 620 500 560 620 500 560 620 mv temperature sensitivity 1.9 1.9 1.9 mv/c output resistance 3 3 3 k? short-circuit current to ground 30 30 30 ma temperature range specified performance (a, b, c) C40 +85 C40 +85 C40 +85 c operating performance (a, b, c) 4 C55 +125 C55 +125 C55 +125 c 1 maximum output voltage drift is guaranteed for all packages. 2 3.0 v mode typically adds 100 a to the quiescent current. also, i q increases by 2 a/v above an input voltage of 5 v. 3 the long-term stability specific ation is noncumulative. the drift in subsequent 1,000 hour periods is significantly lower than in the first 1,000 hour period. 4 the operating temperature range is defined as the temperature extremes at which the device will still function. parts may devia te from their specified performance outside their specified temperature range.
ad780 rev. e | page 4 of 12 absolute maximum ratings table 2. p a r a m e t e r v a l u e s +v in to ground 36 v trim pin to gro u nd 36 v temp pin to ground 36 v power dissi pati on (25c) 500 mw storage temperature ?65c to +150c lead temperature (sol dering 10 s e c) 300c output protecti on output safe for indefinite short to ground and momentary short to v in . esd classification class 1 (1000 v) 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 ; f u n c t i o n al o p era t ion o f t h e de vice a t t h es e o r an y co ndi t i on s ab o v e t h o s e i ndic a te d in t h e op er a t i o na l s e c t io n s o f t h is sp e c if ic a t ion is n o t i m plie d . e x p o sur e t o a b s o l u t e maxi m u m sp e c if ic a t ion s fo r ext e n 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 . 00841-002 nc = no connect ad780 top view (not to scale) nc 1 +v in 2 t emp 3 gnd 4 2.5v/3.0v o/pselect (nc or gnd) nc v out trim 8 7 6 5 f i g u re 2. pin conf ig ur at i o n, 8-l e ad p d i p a n d soic p a ckag es 00841-003 gnd temp +v in trim 2.5v/3.0v o/p select v out gnd fi g u r e 3 . d i e l a y o u t notes bo t h v ou t p a ds shou l d b e c o n n e c te d to t h e output . di e thi c k n ess: t h e s t a n da r d thi c kn es s o f a n al og devi ce s b i p o la r dic e is 2 4 mil 2 mil . di e dim e nsi o n s : t h e d i me ns i o ns g i ve n h a ve a to l e r a nc e of 2 mil . back in g: the st a nda rd b a cksid e sur f ace is si lic o n (n ot pl a t e d ). ana l o g d e vi ces do es n o t r e co m m e nd gold-b ack e d dic e fo r m o st ap p l i c at i o n s . ed g e s : a d i am ond s a w is us e d to s e p a r a te w a fers in to di ce, t h us p r o v idin g p e r p e n d i c u la r e d ges ha lf wa y t h r o ug h t h e die . i n co n t r a st to s c r i b e d dic e , t h is te chniq u e p r o v ides a m o r e u n ifo r m die s h a p e an d si ze . the p e r p e n dic u la r e d g e s faci li t a t e handlin g (such as t w e e ze r p i ck u p ), w h i l e t h e unifo r m sh a p e a nd si ze sim p lif y s u bs tr a t e desig n an d die a t tach. to p s u r f a c e : th e st anda r d t o p s u r f ace o f t h e die is co v e r e d b y a l a y e r of g l a s s i v a t i on . a l l are a s ar e c o ve re d e x c e pt b o nd i n g p a d s a nd s c r i b e li n e s. su r f a c e m e t a l l i z at i o n : t h e m e t a l l iza t io n t o an a l og d e vi ces b i p o la r dic e is a l umin u m . m i nim u m thick n es s is 10,000 ?. b o ndi n g p a ds : a l l b o n d i n g p a ds ha ve a mi ni m u m si ze o f 4.0 mil b y 6.0 mil . the p a s s i v a t io n win d o w s ha v e a minim u m size o f 3.6 mil b y 5.6 mil . 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.
ad780 rev. e | page 5 of 12 theory of operation b a nd ga p r e fer e n c es a r e t h e hig h p e r f o r ma n c e s o l u t i o n fo r lo w su p p ly vol t a g e and lo w p o w e r vol t a g e r e fer e n c e a p plic a t io ns. i n t h is t e chni q u e , a v o l t a g e w i t h a p o si t i v e t e m p era t ur e co ef f i cien t is co m b i n e d wi t h t h e n e ga t i v e c o ef f i cien t o f a t r a n sis t o r s v be to pro d u c e a c o nst a n t b a nd g a p vo l t age. i n t h e ad780, t h e b a n d g a p ce l l co n t a i n s tw o np n tra n sist o r s (q6 a n d q7) t h a t dif f er in emi t t e r a r e a b y 12. the dif f er ence i n th e i r v be s p r o d u c e s a p t a t c u r r e n t i n r 5 . t h i s , i n t u r n , p r o d uces a p t a t v o l t a g e acr o s s r4 t h a t , w h en c o m b i n e d wi t h th e v be o f q7, p r o d uces a v o l t a g e (v bg ) th a t d o es n o t va r y w i th te m p e r atu r e. pre c i s i o n l a s e r t r i m m i ng of t h e re s i stor s an d ot he r p a t e n t e d cir c ui t t e chniq u es a r e us e d t o f u r t h e r enhan c e t h e dr if t pe rf o r m a n c e . 00841-004 r16 r10 +v in r4 r5 q6 q7 r11 r14 r13 r15 nc v out trim gnd o/p select 2.5v ? nc 3.0v ? gnd t emp nc nc = no connect ad780 7 2 1 3 48 5 6 fi g u r e 4 . s c h e m a t i c d i a g r a m the o u t p u t v o l t a g e o f t h e ad78 0 is det e r m in e d b y t h e co nf igura t io n of resis t o r s r13, r14, a nd r15 in th e am p l if ier s f eed back lo o p . this s e ts t h e o u t p u t t o ei t h er 2. 5 v o r 3.0 v , d e p e nd i n g o n w h e t he r r 1 5 ( p i n 8 ) i s g r ou nd e d or not co nne c t e d . a uniq ue f e a t ure o f th e ad780 is th e lo w headro o m desig n o f t h e h i g h ga i n am plif ier , w h ich p r o d uces a p r e c isio n 3 v o u t p u t f r o m a n in p u t vol t a g e as lo w as 4.5 v (o r 2.5 v f r o m a 4.0 v in p u t). the am plif ier desig n a l s o a l lo ws t h e p a r t t o w o rk wi t h +v in = v ou t w h en c u r r en t is fo r c e d i n t o t h e o u t p u t t e r m inal . this al lo ws th e ad780 t o w o rk as a 2-t e r m inal s h un t r e gu l a t o r , prov i d i n g a ? 2 . 5 v or ? 3 . 0 v re f e re nc e vo lt age output w i t h out ext e r n al co m p on e n ts. the p t a t v o l t ag e is als o us e d to p r o v ide t h e us er wi t h a t h er m o met e r ou t p ut v o l t a g e (a t p i n 3) t h a t in c r e a s e s a t a ra te o f a pprox i m a t el y 2 m v / c . the ad780 s nc (p in 7) is a 20 k? r e sis t o r t o +v in th a t i s use d s o le l y fo r p r o d uc t i o n t e st p u r p os es. u s ers w h o ar e c u r r en t l y usin g th e l t 101 9 s e lf-h ea t e r p i n (p in 7) m u s t ta k e in t o ac co un t t h e dif f er en t lo ad o n t h e h e a t er s u p p l y .
ad780 rev. e | page 6 of 12 applying the ad780 the ad780 can be us e d wi t h o u t a n y ext e r n al c o m p on en ts t o achie ve sp e c if ie d p e r f o r ma n c e. i f p o w e r is su p p lie d to pi n 2 and p i n 4 is g r o u nded , p i n 6 p r o v ides a 2.5 v o r 3.0 v o u t p u t dep e n d in g on w h et h e r pi n 8 is lef t un con n e c te d o r g r o u n d e d . a b y pa s s ca pa c i t o r o f 1 f ( + v in t o gnd) sh o u ld be us e d if t h e lo ad ca p a c i t a n c e in t h e a p plic a t io n is exp e c t e d t o b e g r e a t e r tha n 1 nf . th e ad780 in 2.5 v m o de typ i cal l y dra w s 700 a o f i q a t 5 v . this incr eas e s b y ~2 a/v u p t o 36 v . 00841-005 nc temp +v in r null v out trim gnd o/p select 2.5v ? nc 3.0v ? gnd nc r pot 1 f ad780 nc = no connect 1 7 6 5 8 4 2 3 fi g u r e 5 . o p t i o n a l fi n e - t r i m c i r c u i t i n i t ia l er r o r ca n b e n u l l e d usin g a sin g le 25 k? p o t e n t iom e t e r co nne c t e d b e twe e n v ou t , trim , a n d gnd . this is a co a r s e tr im wi t h an ad j u s t men t ra n g e o f 4%, a nd is o n l y in c l uded h e r e f o r c o m p a t i b i l it y p u r p o s e s w i t h ot he r re f e re nc e s . a f i ne t r i m c a n b e im ple m e n t e d b y in s e r t in g a la rge va l u e r e sist o r (e .g., 1 m? t o 5 m?) in s e r i es wi t h t h e wi p e r o f t h e p o t e n t iom e t e r (s e e f i gur e 5). th e t r im ra n g e, exp r ess e d as a f r ac t i o n o f t h e o u t p ut, is sim p l y g r ea t e r tha n o r eq ual to 2.1 k?/r nu ll fo r ei t h er t h e 2.5 v o r 3.0 v m o de . the ext e r n al n u l l r e sis t o r a f fe c t s t h e o v eral l t e m p er a t ur e co ef f i cien t b y a fac t o r e q ual t o t h e p e r c en t a g e of v out nu l l e d . f o r exa m p l e , a 1 mv (0.03%) shif t in the o u t p u t c a us ed b y t h e tr im cir c ui t, wi t h a 100 p p m/c n u l l r e sis t o r , adds les s tha n 0.06 p p m /c t o th e o u t p u t dr if t (0.03% 200 p p m /c, sin c e t h e r e sis t o r s in t e r n a l t o th e ad780 als o ha v e t e m p era t ur e co ef f i cien ts o f les s tha n 100 p p m/c). noise performance the i m p r es si v e n o is e p e r f o r ma n c e o f t h e ad7 80 ca n b e f u r t h e r im p r o v e d , if des i r e d , b y addi n g t w o ca p a ci to rs: a lo ad ca p a ci to r (c1) b e t w e e n t h e o u t p ut and g r o u nd , a nd a com p e n s a t i on ca p a c i to r (c2) b e tw e e n t h e te mp p i n and g r o u nd . s u i t a b le val u es a r e sh o w n in f i gur e 6. 100 10 1 0.1 0.1 1 1 0 100 00841-006 load capacitor, c1 ( f) comp e n s a tion cap acitor, c2 (nf) f i gur e 6 . co m p e n s a ti on and l o a d c a pa ci t o r co m b i n a t io ns c1 a nd c2 als o im p r o v e the s e t t lin g p e r f o r ma n c e o f th e ad780 w h en sub j e c t e d t o lo ad t r a n sien ts. the i m p r o v em e n t i n n o is e p e r f o r m a n c e i s s h o w n i n fi g u r e 7 , fi g u r e 8 , fi g u r e 9 , a n d f i gur e 10. 00841-007 0.1 to 10hz amplifier gain = 100 1s 100 v 100 90 10 0% f i g u re 7. st a n da lo ne n o is e p e r f or ma nc e 00841-008 10hz to 10khz no amplifier 10ms 20 v 100 90 10 0% f i g u re 8. st a n da lo ne n o is e p e r f or ma nc e
ad780 rev. e | page 7 of 12 00841-009 nc temp +v in v out trim gnd o/p select 2.5v ? nc 3.0v ? gnd nc 1 f ad780 nc = no connect 1 7 6 5 8 4 2 3 c2 c1 f i gu r e 9 . no i s e re du cti o n cir c ui t noise c o m p ariso n the wideb a nd n o is e p e r f o r ma n c e o f t h e ad7 80 ca n als o b e exp r es s e d i n p p m. th e typ i cal p e r f o r ma n c e w i t h c1 and c2 is 0 . 6 ppm ; w i t h o u t e x te r n a l c a p a c i tor s , t y pi c a l p e r f or m a nc e i s 1.2 p p m . this p e r f o r ma nce is, r e sp e c t i v e l y , 7 a n d 3 lo w e r t h a n t h e s p ecif ie d p e r f o r ma nce o f th e l t 1019. 00841-010 10hz to 10khz no amplifier 10ms 20 v 100 90 10 0% f i gur e 1 0 . re duc e d no i s e p e r f o r ma nc e wi th c1 = 100 f , c2 = 10 0 nf temperature perfor mance the ad780 p r o v ides su p e r i o r p e r f o r ma n c e o v er t e m p er a t ur e b y m e an s o f a com b in a t ion o f p a te n t e d cir c ui t des i g n te ch niq u es, p r e c isio n t h i n -f i l m r e sisto r s, a nd dr if t t r imm i ng. t e m p er a t ur e p e r f o r ma n c e is sp e c if ie d i n t e r m s o f p p m /c; b e ca us e o f n o nl ine a r i ty i n t h e tem p era t ur e cha r ac t e r i s t ic, t h e b o x t e st m e t h o d i s used t o t e s t a n d s p ecif y th e pa r t . t h e n o nli n ea ri t y tak e s t h e f o rm o f th e c h a r a c t e ri sti c s- s h a p e d cur v e s h o w n i n f i g u re 1 1 . t h e b o x te st me t h o d f o r m s a re c t ang u l a r b o x arou nd t h is c u r ve, en clo s in g t h e max i m u m and m i ni m u m o u t p ut v o l t a g es o v er t h e s p e c if ie d t e m p era t ur e ra n g e . the s p e c if ie d d r i f t i s e q u a l to t h e sl op e of t h e d i agon a l of t h i s b o x . 2.0 ?0.8 ?0.4 0 0.4 0.8 1.2 1.6 ? 6 0 ? 40 ? 2 0 0 20 40 60 80 100 120 140 00841-011 temperature ( c) e rror (mv ) f i g u re 11. t y pic a l a d 78 0bn t e mper at ur e d r if t temperature output pin the ad780 p r o v ides a temp ou t p u t (p in 3) tha t va r i es lin e a r ly w i t h te m p e r a t u r e. th i s output c a n b e u s e d to mon i tor ch a n ge s in sy st e m am b i e n t t e m p er a t ur e , a nd t o in i t ia t e c a li b r a t ion o f t h e sys t em, if desir e d . th e v o l t a g e v te mp is 560 mv a t 25c, an d t h e t e m p era t ur e co ef f i cien t is a p p r o x ima t e l y 2 mv /c. f i gur e 12 s h o w s th e typ i cal v te mp cha r ac t e r i s t ic c u r v e o v er t e m p era t ur e t a k e n a t t h e o u t p u t o f t h e o p a m p wi t h a non i n v e r t i ng g a i n of 5 . 4.25 4.00 3.75 3.50 3.25 3.00 2.75 2.50 2.25 2.00 ? 7 5 ? 50 ?25 0 25 50 75 100 125 150 00841-012 temperature ( c) voltage (v out ) circuit calibrated at 25 c refer to figure 13 10mv per c f i g u re 12. t e mpe r a t ur e pin t r ans f er c h ar ac t e ris t i c sin c e t h e tem p v o l t a g e is ac quir e d f r o m t h e b a nd ga p co r e cir c ui t, c u r r en t p u l l e d f r o m t h is p i n has a sig n if ica n t ef fe c t o n v ou t . c a r e m u s t be ta k e n t o b u f f e r th e t e mp o u t p u t wi th a s u i t ab le o p a m p , e . g., an o p 07, ad820, o r ad7 11 (al l o f whic h w o u l d r e s u l t in l e s s tha n a 100 v c h a n g e in v o ut). th e r e la ti o n s h i p be tw ee n i te mp and v ou t is ? v ou t = 5.8 mv/a i tem p (2.5 v ra n g e ) or ? v ou t = 6.9 mv/a i tem p (3.0 v ra n g e )
ad780 rev. e | page 8 of 12 n o t i ce h o w s e nsi t i v e t h e c u r r en t dep e n d en t f a c t o r o n v ou t is. a l a r g e a m ou n t of c u r r e n t , e v e n i n te ns of m i c r o a m p , d r aw n f r om t h e temp p i n c a n c a us e t h e v out a nd tem p ou t p u t t o fa il . the ch o i ce o f c 1 a nd c2 was dic t a t e d p r ima r il y b y th e n e e d f o r a r e l a ti ve l y f l a t res p o n s e tha t r o l l ed o f f ea rl y in th e hig h f r e q uen c y n o is e a t t h e o u t p ut. h o w e v e r , t h er e is co n s idera b le ma rg in in t h e ch o i ce o f t h es e c a p a ci t o rs. f o r exa m ple , t h e us e r ca n ac t u al l y p u t a h u g e c2 on t h e temp p i n wi th n o n e on the output pi n . h o we ve r , on e m u st e i t h e r put ve r y l i tt l e or a l o t of ca p a c i t a n c e a t t h e temp p i n. i n t e r m e d i a t e va l u es o f c a pa ci ta n c e c a n so m e tim e s ca u s e osc i ll a t io n . i n a n y ca se , th e u s e r shou l d f o l l ow t h e re c o m m e n d a t i on i n fi g u re 6 . temperature transducer circuit the cir c ui t sh ow n in f i gur e 13 is a t e m p era t ure t r a n s d ucer t h a t a m p l if ies t h e temp o u t p u t v o l t a g e b y a ga in of a li t t le o v er +5 to prov i d e a w i d e r f u l l - s c a l e output r a nge. t h e d i g i t a l p o te n t i o me te r c a n b e u s e d to a d j u st t h e out p ut s o i t v a r i e s b y exac tl y 10 mv/c. t o minimize r e sis t an ce c h an g e s wi t h t e m p era t u r e , r e sis t o r s wi t h lo w t e m p er a t ure co ef f i cien ts, such as m e t a l f i l m r e sis t o r s, shou l d b e u s e d . 00841-013 ad780 gnd r b 1.27k ? (1%) r f 6.04k ? (1%) 4 +v in 2 3 1 f temp r bp 200 ? ad820 10mv/ c 5v f i gure 13. d i ffe r e nt ia l t e mper ature t r a n sduc er supply cur r ent over temperature the ad780 s q u ies c en t c u r r en t va r i es s l ig h t l y o v er t e m p er a t ur e a nd in p u t s u p p ly ra n g e . the t e st limi t is 1 ma o v er th e ind u s t r i al and 1 . 3 ma o v er t h e mi li t a r y t e m p er a t ur e ra n g e . t y p i cal p e r f o r ma n c e w i t h in p u t v o l t a g e and t e m p era t ur e va r i a t ion is sh o w n in f i gur e 14. 0.85 0.80 0.75 0.70 0.65 0.60 43 00841-014 input voltage (v) quie s c e n t curre nt (ma) ?55 c +25 c +125 c 6 f i gure 14. t y pic a l s u p p ly cu rrent o v e r t e m p er ature turn-o n ti me the t i m e r e q u ir e d fo r t h e o u t p ut v o l t a g e t o r e ach i t s f i na l val u e wi t h in a sp e c if i e d er r o r b a nd is def i n e d as t h e tur n -o n s e t t lin g ti m e . th e t w o m a jo r fa ct o r s tha t a f f e ct th i s a r e th e a c t i v e ci r c ui t se t t li n g tim e a n d th e tim e f o r th e t h e r m a l gra d i e n t s o n t h e c h i p t o s t a b ilize . t y p i cal s e t t lin g p e r f o r ma n c e is sh own in f i gur e 15. the ad780 s e t t les t o wi thin 0.1 % o f i t s f i nal va l u e wi t h in 10 s . 5v 0v 2.500v 2.499v 2.498v 00841-015 10 s/div v in v out f i gure 15. t u rn- o n s e ttli n g tim e p e r f o r m a nce dynamic performance the o u t p u t sta g e o f th e ad780 has b e en des i g n ed t o p r o v ide su p e r i o r st a t ic and d y namic lo ad r e gu la t i o n . f i gur e 16 a nd f i gur e 17 s h o w t h e p e r f o r ma n c e o f th e ad780 while dr iving a 0 ma t o 10 ma lo ad .
ad780 rev. e | page 9 of 12 00841-016 ad780 4 +v in 2 6 1 f v out 249 ? v l v out 0v f i gur e 1 6 . t r a n sient resi sti v e l o a d t e s t ci r c ui t 0ma 10ma 00841-017 10 s/div outp ut change (5 0 m v / div ) i load v out (c l = 0pf) f i gur e 1 7 . settli n g under t r a n sient resi sti v e l o a d the d y na mic lo ad ma y b e r e sis t i v e an d ca p a c i t i v e . f o r exa m ple , th e lo ad ma y b e co nnec t e d via a lo n g ca p a c i ti v e ca b l e . f i gur e 18 a nd f i gur e 19 sh o w t h e p e r f o r ma nce o f th e ad780 dr i v in g a 1000 pf , 0 ma t o 10 ma lo ad . 00841-018 ad780 4 +v in 2 6 1 f v out 249 ? v l v out 0v c l 1000pf f i gur e 1 8 . c a p a ci tiv e l o a d t r a n si ent resp o n se t e st cir c uit 0ma 10ma 00841-019 10 s/div outp ut change (5 0 m v / div ) i load v out (c l = 1000pf) f i gure 1 9 . settli n g under d y na mi c c a pa ci ti v e l o a d line regulatio n l i ne r e g u l a t i on i s a m e a s u r e of ch ange i n output vo lt age d u e to a sp e c if ie d change in i n p u t v o l t age . i t is in t e nde d t o sim u la t e w o rst-c a s e unr e gu la te d sup p ly co n d i t io ns an d is m e a s ur e d i n v/v . f i gur e 20 s h o w s ty p i cal p e r f o r ma n c e wi t h 4.0 v < v in < 15.0 v . 200 100 0 ?100 ?200 41 10 00841-020 input voltage (v) outp ut change ( v) t = 25 c 5 f i g u re 20. o u t p ut v o lt ag e ch ang e v s . i n put v o lt ag e precision reference for high resolution 5 v da ta c o n v erters the ad780 is ideal l y s u i t e d t o be t h e r e f e r e nce f o r m o s t 5 v hig h r e s o l u tion ad cs. the ad780 is s t a b le u nder a n y c a p a ci tiv e lo ad , has s u p e r i o r d y na mic lo ad p e r f o r ma n c e , a nd i t s 3.0 v o u t p ut p r o v ides t h e con v er t e r w i t h t h e maxi m u m d y na mic ra n g e w i t h o u t re q u ir in g an addi t i o n al and exp e n s i v e b u f f er a m plif ier . one o f t h e man y a d cs t h a t t h e ad7 80 is sui t e d fo r is th e ad7884, a 1 6 -b i t , hig h s p ee d s a m p l i n g ad c (s ee f i gur e 21 ). this p a r t p r e v iously n e e d e d a pr e c isio n 5 v r e fer e n c e , r e sist o r divider , an d b u f f er a m plif ier to do t h is f u n c t i on .
ad780 rev. e | page 10 of 1 2 00841-021 +v in ad780 ad7884 v out v ref + f 6 v ref + s 2.5v/3.0v select 8 gnd 4 2 1 f 5v f i g u re 21. p r ec is io n 3 v r e f e r e nc e f o r t h e a d 7 8 84 1 6 -bit , hig h speed a d c the ad780 is als o ideal f o r us e wi t h hig h er r e s o l u tio n co n v er t e rs, s u c h as th e ad7710 /ad7711/ad77 12 (s ee f i gur e 22. w h ile th es e p a r t s a r e s p ecif ied wi t h a 2.5 v in t e r n al r e f e r e n c e , the ad780 in 3 v m o de can be us ed to im p r o v e th e a b s o l u te a c c u r a c y , tem p er a t ur e st a b i l i t y , a nd dy na mic r a n g e. i t i s s h o w n i n f i g u r e 2 2 w i th th e t w o o p t i o n a l n o i s e r e d u ct i o n ca p a c i t o rs. 00841-022 +v in ad780 ad7710 v out ref in+ 6 2.5v/3.0v o/p select 8 gnd 4 3 2 1 f 100nf 5v ref in? 100 f f i g u re 22. p r ec is io n 2. 5 v or 3. 0 v r e f e renc e f o r t h e a d 77 10 h i g h r e s o l u t i on, -? a d c 4.5 v reference from 5 v suppl y s o m e 5 v h i g h re s o lut i on a d c s c a n a c c o m m o d a t e re f e re nc e v o l t a g es u p t o 4. 5 v . the ad780 ca n be us e d t o p r o v ide a p r ecisio n 4.5 v r e f e r e n c e v o l t a g e f r o m a 5 v s u p p l y usin g th e c i rc u i t s h ow n i n f i g u re 2 3 . t h i s c i rc u i t prov i d e s a re g u l a te d 4.5 v o u t p ut f r o m a su p p ly vol t a g e as lo w as 4.7 v . the hig h q u ali t y tan t al u m 10 f ca p a c i to r , in p a ral l e l wi th the cera mic ad780 0.1 f c a p a ci t o r and t h e 3.9 ? r e sis t o r , e n s u r e s a lo w o u t p ut im p e dance a r o u nd 50 m h z. 00841-023 ad780 2n2907 v out 5k ? 0.01% 4k ? 0.01% 2.5k ? 3.9 ? 1k ? 0.1 f 0.1 f 10 f 0.1 f op90 + ? v supply 2 4 6 3 7 6 4 2 f i g u re 23. 4. 5 v r e f e r e nc e f r o m a s i ng l e 5 v sup p l y negative (C 2.5 v) reference the ad780 can p r o d uce a nega ti v e o u t p u t v o l t a g e in s h u n t m o d e b y co n n e c t i n g t h e i n p u t a nd o u t p u t to g r o u n d , and co nnec t in g t h e ad780 s gnd p i n t o a nega t i ve s u p p l y via a b i as re s i stor , a s show n i n fi g u re 2 5 . 00841-024 nc temp +v in v out trim gnd o/p select 2.5v ? nc 3.0v ? gnd nc 1 f ad780 notes 1. i l = load current 2. i s min = minimum shunt current 3. nc = no connect 1 7 6 5 8 4 2 3 r = v out ? (v ?) i l + i s min ?2.5 v out v? f i g u re 24. neg a t i ve (?2. 5 v s h unt m o d e r e f e rence) a p r ecis e C2.5 v r e f e r e n c e c a p a b l e o f s u p p l y ing u p t o 100 ma t o a lo ad can be im p l em en t e d wi th the ad780 in s e r i es m o de , u s i n g t h e b o ot st r a p c i rc u i t s h ow n i n fi g u re 2 5 . 0 0841-025 ad780 2n3906 +5v +5v op07 connect if ?3v output desired ?2.5v (i l 100ma) ?5v ?5v out 1k ? 1000pf +v in ? + 2 4 68 f i gure 25. ? 2 .5 v h i gh l oad cu rrent r e fer e n c e
ad780 rev. e | page 11 of 1 2 outline dimensions 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) 0.50 (0.0196) 0.25 (0.0099) 45 8 0 1.75 (0.0688) 1.35 (0.0532) seating plane 0.25 (0.0098) 0.10 (0.0040) 4 1 85 5. 0 0 ( 0 . 1 968) 4. 8 0 ( 0 . 1 890) 4.00 (0.1574) 3.80 (0.1497) 1.27 (0.0500) bsc 6.20 (0.2440) 5.80 (0.2284) 0.51 (0.0201) 0.31 (0.0122) coplanarit y 0.10 controlling dimensions are in millimeters; inch dimensions (in parentheses) are rounded-off millimeter equivalents for reference only and are not appropriate for use in design compliant to jedec standards ms-012aa f i g u re 26. 8-l e ad s t anda r d s m a l l o u t l ine p a ckag e [soic ] narro w b o dy (r -8) di me nsio ns sho w n i n mi ll im e t e r s a n d (i nc he s) seating plane 0.015 (0.38) min 0.180 (4.57) max 0.150 (3.81) 0.130 (3.30) 0.110 (2.79) 0.060 (1.52) 0.050 (1.27) 0.045 (1.14) 8 1 4 5 0.295 (7.49) 0.285 (7.24) 0.275 (6.98) 0.100 (2.54) bsc 0.375 (9.53) 0.365 (9.27) 0.355 (9.02) 0.150 (3.81) 0.135 (3.43) 0.120 (3.05) 0.015 (0.38) 0.010 (0.25) 0.008 (0.20) 0.325 (8.26) 0.310 (7.87) 0.300 (7.62) 0.022 (0.56) 0.018 (0.46) 0.014 (0.36) controlling dimensions are in inches; millimeter dimensions (in parentheses) are rounded-off inch equivalents for reference only and are not appropriate for use in design compliant to jedec standards mo-095aa f i g u re 27. 8-l e ad p l as t i c d u a l -in-li ne p a ckag e [p dip ] (n-8) di me nsio ns sho w n i n i n che s a n d ( m il lim e t e r s)
ad780 rev. e | page 12 of 1 2 orderi ng guide model initial error temperature r a nge temperature c o efficient package option qty. per tube/ r eel ad780an 5.0 mv ?40c to +85c 7 ppm/c pdip 48 ad780ar 5.0 mv ?40c to +85c 7 ppm/c soic 98 ad780ar-re el7 5.0 mv ?40c to +85c 7 ppm/c soic 750 ad780arz 1 5.0 mv ?40c to +85c 7 ppm/c soic 98 ad780bn 1.0 mv ?40c to +85c 3 ppm/c pdip 48 ad780br 1.0 mv ?40c to +85c 3 ppm/c soic 98 ad780brz 1 1.0 mv ?40c to +85c 3 ppm/c soic 98 ad780br-reel 1.0 mv ?40c to +85c 3 ppm/c soic 2,500 ad780br-reel7 1.0 mv ?40c to +85c 3 ppm/c soic 750 ad780brz 1 1.0 mv ?40c to +85c 3 ppm/c soic 98 ad780brz-reel 7 1 1.0 mv ?40c to +85c 3 ppm/c soic 750 ad780cr 1.5 mv ?40c to +85c 7 ppm/c soic 98 ad780cr-ree l 7 1.5 mv ?40c to +85c 7 ppm/c soic 750 ad780crz 1 1.5 mv ?40c to +85c 7 ppm/c soic 98 1 z = pb-free part. ? 2004 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 . c00841C0 C 5/04(e)

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