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precision low power single-supply jfet amplifier ad8627/ad8626/ad8625 rev. b in fo rmation furn is h e d by an al o g dev i ces is believed to be a ccu rate and r e liable. how e ver, no r e spons i bili ty is assumed by analog devices fo r its use, nor f o r an y i n fri n geme nt s of p a t e nt s or ot her ri g h t s o f th ird parties th at may result fro m its use . specifications subject to chan g e witho u t n o tice. no licen s e is g r an te d by implicati o n or ot he rwi s e un der a n y p a t e nt or p a t e nt r i ghts of anal og de vices. trad emarks 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 sc70 package very low i b : 1 p a max single-supply operation: 5 v to 26 v dual -supply o p eratio n: 2.5 v to 13 v rail-to-rail out p ut low supply current: 630 a /amp typ low offset voltage: 500 v ma x unity gain st able no phase rever s al applic ati o ns photodiode amplifiers ate line-powered/battery-powered instrum e nta t ion industrial cont rols automotive se nsors precision filter s audio general description the ad862x is a p r ecisio n jfet in p u t am p l if ier . i t f e a t ur es t r ue sin g le-su p ply o p er a t io n, lo w p o w e r co n s u m p t ion, an d ra il-t o-ra il o u t p u t . th e o u t p u t s r e ma in sta b le wi th ca p a ci ti v e l o a d s o f o v e r 500 p f ; th e s u p p l y cu rr en t i s l e s s tha n 6 3 0 a/ a m p . a p p l ica t io n s f o r th e ad862x in c l ud e ph o t odi o de tra n sim p e d a n ce a m plif ic a t ion, a t e r e fer e n c e l e ve l dr i v ers, b a t t er y ma na ge m e n t , b o t h li ne p o w e r e d and p o r t a b le in st r u m e n t a t ion, a nd r e m o te s e ns or s i g n a l c o nd i t i o n i ng i n clu d i n g a u to mot i v e s e ns or s . the ad862x s ab ili t y t o s w in g nea r l y ra il-t o-ra il a t t h e in p u t a nd ra i l - t o-ra i l a t t h e o u t p ut ena b les i t t o b e us e d t o b u f f er cmos d a cs, as i c s, an d o t h e r wide o u t p u t s w in g de vices in sin g le-s u p p l y sys t em s. the 5 mh z b a nd w i d t h an d lo w o f fs et a r e ide a l fo r p r e c isio n fi l t e r s . the ad862x is f u l l y s p ecif ied o v er th e ind u s t r i al t e m p era t ur e ra n g e . (C40 t o +85) the ad8 627 is a v a i la b l e in bo th 5-lead sc70 a nd 8-lead so i c s u r f ace-m o u n t p a c k a g es. th e s c 70 p a c k a g e d p a r t s a r e a v a i la b l e in ta p e an d r e e l o n l y . th e ad8626 is a v a i la b l e in an mso p p a c k a g e . pin c o nfig uratio ns 03023-b - 001 2 3 1 4 5 out a v? +in v+ ?in ad8627 5-lead sc70 (ks suffix) nc ?in v + 2 +in out 3 v? n c 4 nc 1 7 6 5 8 ad8627 nc = no connect 8-lead soic (r-8 suffix) out a ?in a out b 2 +in a ? in b 3 v ? +in b 4 v+ 1 7 6 5 8 ad8626 8-lead soic (r-8 suffix) v+ out a out b ?in a ? in b +in a +in b v? ad8626 8-lead msop (rm-suffix) 5 8 4 1 out a out d 11 4 ?in a ? in d 21 3 +in a +in d 31 2 v+ v ? 41 1 +in b +in c 51 0 ?in b ? in c 69 out b out c 78 ad8625 14-lead soic (r-suffix) out d out a ?in d ? in a +in d +in a v? v+ +in c +in b ?in c ? in b out c out b ad8625 14-lead tssop (ru-suffix) 8 14 7 1 fi g u r e 1 .
ad8627/ad8626/ad8625 rev. b | page 2 of 20 table of contents ad8627/ad8626/ad8625Cspecifications ................................... 3 electrical characteristics ............................................................. 3 electrical characteristics ............................................................. 4 absolute maximum ratings ............................................................ 5 typical performance characteristicsC ad8627/ad8626/ad8625 .............................................................. 6 applications ..................................................................................... 13 minimizing input current ........................................................ 15 photodiode preamplifier application ...................................... 15 output amplifier for digital-to-analog converters ............. 15 eight-pole sallen key low-pass filter ..................................... 16 outline dimensions ....................................................................... 18 ordering guide .......................................................................... 19 revision history 1/04data sheet changed from rev. a to rev. b change to general description ......................................................... 1 change to figure 10 ............................................................................ 7 change to figure13 ............................................................................. 7 change to figure 37 .......................................................................... 11 changes to figure 38......................................................................... 12 change to output amplifier for dacs section ............................. 15 updated outline dimensions .......................................................... 19 10/03data sheet changed from rev. 0 to rev. a addition of two new parts . universal change to general description . ... 1 changes to pin configurations ....................................... 1 change to specifications table . . 3 changes to figure 31 ................................... .... 10 changes to figure 32 ..................................... .. 11 changes to figure 38 .................................... ... 12 changes to figure 46 .................................... ... 16 changes to figure 47 ..................................... .. 16 changes to figure 49 ..................................... .. 17 updated outline dimensions .. 18 changes to ordering guide ........................................ .. 19
ad8627/ad8626/ad8625 rev. b | page 3 of 20 ad8627/ad8626/ad8625Cspecifications electrical characteristics table 1. @v s = 5 v, v cm = 1.5 v, t a = 25c, unless otherwise noted. parameter symbol conditions min typ max unit input characteristics offset voltage v os 0.05 0.5 mv ?40c < t a < +85c 1.2 mv input bias current i b 0.25 1 pa C40c < t a < +85c 60 pa input offset current i os 0.5 pa C40c < t a < +85c 25 pa input voltage range 0 3 v common-mode rejection ratio cmrr v cm = 0 v to 2.5 v 66 87 db large signal voltage gain a vo r l = 10 k?, vo = 0.5 v to 4.5 v 100 230 v/mv offset voltage drift ?v os /?t C40c < t a < +85c 2.5 v/c output characteristics output voltage high v oh 4.92 v i l = 2 ma, C40c < t a < +85c 4.90 v output voltage low v ol 0.075 v i l = 2 ma, C40c < t a < +85c 0.08 v output current i out 10 ma power supply power supply rejection ratio psrr v s = 5 v to 26 v 80 104 db supply current/amplifier i sy 630 785 a C40c < t a < +85c 800 a dynamic performance slew rate sr 5 v/s gain bandwidth product gbp 5 mhz phase margin ? m 60 degrees noise performance voltage noise e n p-p 0.1 hz to 10 hz 1.9 v p-p voltage noise density e n f = 1 khz 17.5 nv/hz current noise density i n f = 1 khz 0.4 fa/hz channel separation cs f = 1 khz 104 db
ad8627/ad8626/ad8625 rev. b | page 4 of 20 electrical characteristics table 2. @v s = 13 v; v cm = 0 v; t a = 25c, unless otherwise noted. parameter symbol conditions min typ max unit input characteristics offset voltage v os 0.35 0.75 mv C40c < t a < +85c 1.35 mv input bias current i b 0.25 1 pa C40c < t a < +85c 60 pa input offset current i os 0.5 pa C40c < t a < +85c 25 pa input voltage range C13 +11 v common-mode rejection ratio cmrr v cm = C13 v to +10 v 76 105 db large signal voltage gain a vo r l = 10 k?, v o = C11 v to +11 v 150 310 v/mv offset voltage drift ?v os /?t C40c < t a < +85c 2.5 v/c output characteristics output voltage high v oh +12.92 v v oh i l = 2 ma, C40c < t a < +85c +12.91 v output voltage low v ol C12.92 v v ol i l = 2 ma, C40c < t a < +85c C12.91 v output current i out 15 ma power supply power supply rejection ratio psrr v s = 2.5 v to 13 v 80 104 db supply current/amplifier i sy 710 850 a C40c < t a < +85c 900 a dynamic performance slew rate sr 5 v/s gain bandwidth product gbp 5 mhz phase margin ? m 60 degrees noise performance voltage noise e n p-p 0.1 hz to 10 hz 2.5 v p-p voltage noise density e n f = 1 khz 16 nv/hz current noise density i n f = 1 khz 0.5 fa/hz channel separation cs f = 1 khz 105 db
ad8627/ad8626/ad 8625 r e v. b | pa ge 5 o f 2 0 absolute maximum ratings 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 o t h e r con d i t io ns a b o v e t h o s e i ndic a te d i n t h e op er a t io 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 ab s o lute m a x i m u m r a t i ng c o nd it i o ns for e x te nd e d p e r i o d s m a y a f fe c t de vice r e l i ab i l i t y . a b s o l u te max i m u m ra t i n g s a p ply a t 2 5 c , u n l e ss ot h e r w i s e note d. t a b l e 3. s t r e ss r a t i n g s p a r a m e t e r r a t i n g supply voltage 27 v input voltage v sC to v s+ differential input voltage supply voltag e output short ci rcuit du r a t i o n i n d e f i n i t e storage temperature range, r p a ckage C65c to + 125c operating temperature range C40c to + 85c junction tempe r ature range, r package C65c to 150c lead temperature range (soldering, 60 sec) 300c t a bl e 4. package type ja 1 jc unit 5-lead sc70 (ks ) 376 126 c/w 8-lead msop (rm) 210 45 c/w 8-lead soic (r) 158 43 c/w 14-lead soic (r) 120 36 c/w 14-lead tssop (ru) 180 35 c/w 1 ja is s p e c if i e d f o r wo rs t case co nd itio ns whe n de vice s are so ld e r e d in circuit board s for s urf ac e-mount packages . esd c a ution 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.
ad8627/ad8626/ad 8625 r e v. b | pa ge 6 o f 2 0 typical performance charac teristicsCad 8627/ad8626/ad8625 03023-b - 002 vo l t a g e ( v) 25 20 0 ?600 ? 400 numbe r of amp l ifie rs ? 200 0 200 400 600 15 10 5 v sy = 12v t a = 25 c f i gure 2. input o ffs et v o lt age o f f set vo l t a g e ( v/ c) 12 0 012 34 567 89 1 0 03023-b - 003 numbe r of amp l ifie rs 6 4 2 8 10 v sy = 13v f i gure 3. o ffset v o l t age d r if t vo l t a g e ( v) 18 16 14 12 10 8 6 4 2 0 ?400 ? 300 ?200 ? 100 0 100 200 300 03023-b - 004 numbe r of amp l ifie rs v sy = +3.5v/ ?1.5v f i gure 4. input o ffs et v o lt age o f f set vo l t a g e ( v/ c) 16 14 12 10 8 6 4 2 0 012 3 456 7 89 1 0 03023-b - 005 number of amplifiers v sy = +3.5v/? 1.5v f i gure 5. o ffset v o l t age d r if t v cm (v) 50 ?50 ?40 ?30 ?20 ?10 0 10 20 30 40 ?15.0 ?12.5 ?10.0 ?7.5 ? 5.0 ? 2.5 0 2.5 5.0 7.5 10.0 12.5 15.0 03023-b - 006 inp u t bias curre nt (pa) v sy = 13v t a = 25 c f i gure 6. input bi as current v s . v cm v cm (v) ?0.9 0 ?0.1 ?0.2 ?0.3 ?0.4 ?0.5 ?0.6 ?0.7 ?0.8 ?15.0?12.5? 10.0 ?7.5 ? 5.0 ? 2.5 0 2.5 5.0 7.5 10.0 12.5 15.0 03023-b - 007 inp u t bias curre nt (pa) v sy = 13v t a = 25 c f i gure 7. input bi as current v s . v cm
ad8627/ad8626/ad 8625 r e v. b | pa ge 7 o f 2 0 t emper a t u r e ( c) 0.1 100 10 1 ? 5 0 ? 25 0 2 5 5 0 7 5 100 125 150 03023-b - 008 inp u t bias curre nt (pa) v sy = 13v v cm = 0v f i gure 8. input bi as current v s . t e mpe r atur e v cm (v) ?2.0 ?1.5 ?1.0 ?0.5 0 0.5 1.0 1.5 2.0 ? 5 ? 4 ? 3 ? 2 ? 1 0 12355 03023-b - 009 inp u t bias curre nt (pa) v sy = +5v or 5v f i gure 9. input bi as current v s . v cm v cm (v) ?100 0 100 200 300 400 500 600 700 800 900 1000 ? 1 5 ? 1 2 ? 9 ? 6 ? 3 0369 1 2 1 5 03023-b - 010 in pu t offset volta ge ( v) v sy = 13v f i gure 10. input o f f s et v o ltag e v s . v cm v cm (v) ?500 ?400 ?300 ?200 ?100 0 100 200 300 400 500 ? 1 01234 03023-b - 011 in pu t offset volta ge ( v) v sy = 5v f i gure 11. input o f f s et v o ltag e v s . v cm l o ad re s i s t an ce ( k ? ) 10k 100k 1m 10m 0.1 1 1 0 100 03023-b - 012 open- l oop gain ( v /v) v sy = +5v v sy = 13v f i gure 12. o p en-l oop g a in vs . l o ad r e sistanc e t emper a t u r e ( c) 1 10 100 1000 ?40 2 5 9 5 125 03023-b - 013 open- l oop gain ( v /mv) e c b d a a. v sy = 13v, v o = 11v, r l = 10k ? b. v sy = 13v, v o = 11v, r l = 2k ? c. v sy = +5v, v o = +0.5v/+4.5v, r l = 2k ? d. v sy = +5v, v o = +0.5v/+4.5v, r l = 10k ? e. v sy = +5v, v o = +0.5v/+4.5v, r l = 600 ? f i gure 13. o p en-l o o p g a in v s . t e mper atur e
ad8627/ad8626/ad 8625 r e v. b | pa ge 8 o f 2 0 o u t p u t vo l t a g e (v) ? 400 ? 300 ? 200 ? 100 0 100 200 300 400 500 600 ? 1 5 ? 10 ?5 0 5 10 15 03023-b - 014 offset voltage ( v) v sy = 13v r l = 100k ? r l = 10k ? r l = 600 ? f i gure 14. input e r ror v o lt age v s . o u tput v o ltag e fo r r e s i s t ive l oads o u t p u t vo l t a g e f r o m s u ppl y r a i l s (m v) ? 250 ? 200 ? 150 ? 100 ?50 0 50 100 150 200 250 0 5 0 100 150 200 250 300 03023-b - 015 input voltage ( v) neg rail pos rail v sy = 5v r l = 1k ? r l = 100k ? r l = 10k ? r l = 10k ? r l = 1k ? f i gure 15. input e r ror v o lt age v s . o u tput v o l t a g e wi thi n 30 0 m v o f sup p ly rails t o t a l s u ppl y v o l t a g e (v) 0 100 200 300 400 500 600 700 800 0 4 8 12 16 20 24 28 03023-b - 016 quie s c e n t curre nt ( a) +125 c +25 c ?5 5 c f i gure 16. q u ies c e n t current v s . sup p l y v o lt ag e at d i f f e rent t e mpe r at u r es l o ad c urre n t ( m a) 1 10 100 1k 10k 0.001 0.01 0.1 1 1 0 100 03023-b - 017 v sy output voltage (mv) v oh v ol v sy = 13v f i g u re 17. o u t p ut s a t u r a t i on v o lt ag e v s . l oad cur r ent l o ad c urre n t ( m a) 1 10 100 1k 10k 0.001 0.01 0.1 1 1 0 100 03023-b - 018 v sy output voltage (mv) v sy = 5v v ol v oh f i g u re 18. o u t p ut s a t u r a t i on v o lt ag e v s . l oad cur r ent f r eq u e n c y ( hz) ?30 ? 135 ?90 ?45 ?0 45 90 135 180 225 270 315 ?20 ?10 0 10 20 30 40 50 60 70 10k 100k 1m 10m 50m 03023-b - 019 gain ( d b) ph a se ( d egrees) gain phase v sy = 13v r l = 2k ? c l = 40pf f i gure 19. o p en-l oop g a in and phase mar g in vs . f r eq uen c y
ad8627/ad8626/ad 8625 r e v. b | pa ge 9 o f 2 0 f r eq u e n c y ( hz) ?30 ? 135 ?90 ?45 ?0 45 90 135 180 225 270 315 ?20 ?10 0 10 20 30 40 50 60 70 10k 100k 1m 10m 50m 03023-b - 020 gain ( d b) ph a s e ( d egrees) v sy = 5v r l = 2k ? c l = 40pf gain phase f i g u re 20. o p en l o op g a in and phas e m a r g i n v s . f r eq uen c y f r eq u e n c y ( h z ) ?30 ?20 ?10 0 10 20 30 40 50 60 70 1k 10k 100k 1m 10m 50m 03023-b - 021 gain ( d b) g = 100 g = 1 g = 10 v sy = 13v r l = 2k ? c l = 40pf f i g u re 21. cl os ed-l oop g a in v s . f r equ e nc y f r eq u e n c y ( h z ) ?30 ?20 ?10 0 10 20 30 40 50 60 70 1k 10k 100k 1m 10m 50m 03023-b - 022 gain ( d b) g = 100 g = 1 g = 10 v sy = 5v r l = 2k ? c l = 40pf f i g u re 22. cl os ed-l oop g a in v s . f r equ e nc y f r eq u e n c y ( h z ) ?60 ?40 ?20 0 20 40 60 80 100 120 140 1k 10k 100k 1m 10m 03023-b - 023 cmrr (db) v sy = 13v fi g u r e 2 3 . c m r r v s . fr e q u e n c y f r eq u e n c y ( h z ) ?60 ?40 ?20 0 20 40 60 80 100 120 140 1k 10k 100k 1m 10m 03023-b - 024 cmrr (db) v sy =5 v fi g u r e 2 4 . c m r r v s . fr e q u e n c y f r eq u e n c y ( h z ) ?60 ?40 ?20 0 20 40 60 80 100 120 140 1k 10k 100k 1m 10m 03023-b - 025 p s rr (db) +psrr ? psrr v sy = 13 v fi g u r e 2 5 . p s r r v s . fr e q u e n c y
ad8627/ad8626/ad 8625 rev. b | page 10 of 20 f r eq u e n c y ( h z ) ?60 ?40 ?20 0 20 40 60 80 100 120 140 1k 10k 100k 1m 10m 03023-b - 026 p s rr (db) +psrr ? psrr v sy =5 v fi g u r e 2 6 . p s r r v s . fr e q u e n c y f r eq u e n c y ( h z ) 0 30 60 90 120 150 180 210 240 270 300 1k 10k 100k 1m 100m 10m 03023-b - 027 z out ( ? ) g = 100 g = 1 g = 10 v sy = 13v f i gure 27. o u tput imped a nce v s . f r eq uenc y f r eq u e n c y ( h z ) 0 30 60 90 120 150 180 210 240 270 300 1k 10k 100k 1m 100m 10m 03023-b - 028 z out ( ? ) g = 100 g = 1 g = 10 v sy =5 v f i gure 28. o u tput imped a nce v s . f r eq uenc y t i me (4 0 0 s/ di v ) 03023-b - 029 voltage ( 10v/div) input output v sy = 13 v f i gure 29. no p h as e r e vers a l s e t tl in g t im e ( s) ?15 ?10 ?5 0 5 10 15 0 0.5 1.0 1.5 2.5 2.0 03023-b - 030 output sw ing ( v ) ts + (1%) ts + (0.1%) ts ? (1%) ts ? (0.1%) f i gure 3 0 . o u tput s w i n g a n d err o r vs . s e ttl ing ti me ca p a ci t a n c e ( p f ) 0 10 60 50 40 30 20 70 10 100 1k 03023-b - 031 over sh oot ( % ) os ? os+ v s = 13v r l = 10k ? v in = 100mv p-p a v = +1 f i g u re 31. sm a ll s i g n al o v ers h oot v s . l oad cap a c i t a n c e
ad8627/ad8626/ad 8625 rev. b | page 11 of 20 ca p a ci t a n c e ( p f ) 0 10 50 40 30 20 70 60 10 100 1k 03023-b - 032 over sh oot ( % ) os? os+ v s = 2.5v r l = 10k ? v in = 100mv p-p a v = +1 f i g u re 32. sm a ll s i g n al o v ers h oot v s . l oad cap a c i t a n c e t i me (1 s / d i v) 03023-b - 033 volta ge ( 50mv/d i v) v sy = 3v a vo = 100,000v/v 0 f i g u re 33. 0. 1 h z t o 10 h z no is e t i me (1 s / d i v) 03023-b - 034 volta ge ( 50mv/d i v) 0 v sy = 2.5v a vo = 100,000v/v f i g u re 34. 0. 1 h z t o 10 h z no is e f r eq u e n c y ( k h z) 01 2345 6789 1 0 03023-b - 035 volta ge ( n v) 28 35 42 49 56 21 14 7 0 v sy = 13v 19.7nv/ hz f i g u re 35. v o lt ag e nois e d e ns i t y f r eq u e n c y ( k h z) 01 2345 6789 1 0 03023-b - 036 volta ge ( n v) 28 35 42 49 56 21 14 7 0 v sy = 5v 16.7nv/ hz f i g u re 36. v o lt ag e nois e d e ns i t y f r eq u e n c y ( h z ) 1 0 100 1k 1 0 k 100k 03023-b - 037 nois e (db) ?4 0 ?110 ?100 ?9 0 ?8 0 ?7 0 ?6 0 ?5 0 v sy = 5v, v in = 9v p-p v sy = 13v, v in = 18v p-p v sy = 2.5v, v in = 4.5v p-p f i gure 37. t o t a l h a rm oni c d i s t o r ti on + n o is e v s . f r equ e n c y
ad8627/ad8626/ad 8625 rev. b | page 12 of 20 f r eq u e n c y ( h z ) ? 160 ? 150 ? 140 ? 130 ? 120 ? 110 ? 100 ?90 ?80 10 100 1k 10k 100k 03023-b - 049 gain ( d b) v in 2k ? 2k ? 2k ? 20k ? v in = 9v p-p v in = 4.5v p-p v in = 18v p-p f i g u re 3 8 . c h a n n e l s e p a ra t i o n
ad8627/ad8626/ad 8625 rev. b | page 13 of 20 appli c ations the ad862x is o n e o f t h e smal l e s t an d m o s t ec o n o m ical jfet s o f fer e d . i t has tr ue sin g le-s u p p l y ca p a b i l i ty a n d has a n i n p u t v o l t a g e ra n g e t h a t exte n d s b e lo w t h e nega t i ve ra i l , a l l o w i ng t h e p a r t to a c c o mmo d a te i n put s i g n a l s b e l o w g r ou nd. the ra il-t o-ra il o u t p u t o f th e ad862x p r o v ides th e maxim u m dy n a m i c r a nge i n m a n y a p pl i c a t i o ns . t o prov i d e a l o w of f s e t , lo w n o is e , hig h im p e dance in p u t s t a g e , th e ad8 62x us es n-chann e l jfet s the i n p u t comm on- m o d e vol t a g e ext e n d s f r o m 0.2 v be lo w Cv s to 2 v b e l o w + v s . d r i v i n g th e in p u t o f th e a m plif ier , co nf igur e d in un i t y g a in b u f f er , clos e r t h a n 2 v t o t h e p o si t i v e ra i l ca u s es a n i n cr e a s e i n co mm on- m o d e v o l t a g e er r o r , as i l l u st r a te d i n f i gur e 15, a nd a lo ss o f a m plif ier b a ndwid t h . this los s o f ba nd wid t h c a us es th e r o u n din g o f th e o u t p u t wa v e f o r m s sh o w n in f i gur e 39 a nd f i gur e 40, whic h ha v e in p u ts tha t a r e 1 v and 0 v f r o m +v s , re sp e c t i v e ly . the ad862x wi l l n o t exp e r i en c e p h as e r e v e rs al wi t h in p u t sig n als c l os e t o th e p o si t i v e ra il , as sh o w n in f i gur e 29. f o r in p u t volt age s g r e a t e r t h an + v sy , a r e sis t o r in s e r i es wi th the ad862x s n o nin v er t i n g i n p u t p r e v e n ts phas e r e v e rs al a t t h e exp e n s e o f g r e a t e r in p u t v o l t a g e n o is e . this c u r r en t limi t i ng r e sist o r sh o u l d a l s o b e us e d if t h er e is a p o ssib i l i t y o f t h e in pu t v o l t a g e exceedin g t h e p o si ti v e s u p p l y b y m o r e tha n 30 0 mv , o r if a n in p u t v o l t a g e is a p p l ie d t o t h e ad862x when v sy = 0. ei th er o f t h es e condi t i o n s wi l l da m a ge t h e a m plif ier if t h e co ndi t i on exis ts f o r m o r e tha n 10 s e con d s. a 100 k? r e sis t o r al lo ws th e a m plif ier t o wi t h st and u p t o 10 v o f co n t in uo us o v er v o l t a g e , wh ile in cr ea sin g th e in p u t v o l t a g e n o i s e b y a n e gli g i b le a m o u n t . t i me (2 s/ di v ) 03023-b - 038 volta ge ( 2 v/d i v) input output v sy =5 v f i g u re 39. u n it y g a in f o l l ower r e s p on s e to 0 v to 4 v step t i me (2 s/ di v ) 03023-b - 039 volta g e ( 2 v/d i v) input output v sy =5 v f i g u re 40. u n it y g a in f o l l ower r e s p on s e to 0 v to 5 v step
ad8627/ad8626/ad 8625 rev. b | page 14 of 20 the ad862x can s a f e l y wi th stand in p u t v o l t a g es 15 v be lo w v sy if t h e t o t a l vol t a g e b e tw e e n t h e p o si t i v e su ppl y a n d t h e in pu t t e r m inal is les s t h a n 26 v . f i gur e 41 thr o ug h f i gur e 43 s h o w t h e ad862x in dif f er en t co nf igura t io n s acco mm o d a t in g sig n als clos e t o t h e n e g a t i v e rai l . t h e am plif ier in pu t st a g e ty pica l l y m a i n t a i n s pi c o a m p - l e v e l i n put c u r r e n t s a c ro s s t h a t i n put vol t age r a ng e. t i me (2 s/ di v ) 03023-b - 040 volta ge ( 1 v/d i v) +5v 20k ? 10k ? 0v ? 2.5v v sy = 5v, 0v f i g u re 41. g a in of t w o i n ver t er r e s p on s e to 2. 5 v st ep , c e nte r ed C1.25 v b e lo w g r ou nd t i me (2 s/ di v ) 03023-b - 041 volta ge ( 10mv/d i v) 5v 60mv 20mv 600 ? 0v v sy = 5v r l = 600 ? f i gure 42. unit y g a in f o l l ow er respon se to 4 0 mv step , cente r ed 4 0 mv ab o v e g r ound t i me (2 s/ di v ) 03023-b - 042 volta ge ( 10mv/d i v) +5v 20k ? 10k ? ?10mv ?30mv 0v v sy = 5v f i g u re 43. g a in of t w o i n ver t er r e s p on s e to 2 0 mv step , c e nte r ed 20 mv be lo w g r ound the ad862x is desig n e d f o r 16 nv/ h z wideband in p u t v o l t a g e noi s e a n d m a i n t a i n s l o w noi s e p e r f o r m a nc e to l o w f r e q u e nc i e s , a s s h ow n i n fi g u re 3 5 . t h i s noi s e p e r f or m a nc e, a l ong w i t h t h e ad862x s lo w in p u t c u r r en t and c u r r en t n o is e , m e an s tha t the ad862x co n t r i b u t e s neg l ig i b le n o is e f o r a p p l ic a t io n s wi th l a rg e s o ur ce r e sis t a n c e s. the ad862x has a uniq ue b i p o l a r ra il-t o-ra il o u t p u t s t a g e tha t sw in gs w i th in 5 m v o f th e ra il wh e n u p t o 2 ma o f curr e n t i s dr a w n. a t la rger lo ads, t h e dr o p -o u t vol t a g e i n c r e a s e s as sh o w n in f i gur e 17 and f i gur e 18. the ad862x s wide ban d wid t h a nd fas t s l e w r a te a l l o ws i t to b e us e d wi t h f a ster s i g n als t h an p r e v io u s sin g le-s u p p l y jfet s. f i gur e 44 s h o w s the r e s p on s e o f ad862x, co nf igur e d in u n i t y ga i n , t o a v in o f 20 v p-p a t 50 kh z. th e fp b w o f th e p a r t is c l os e t o 100 kh z. t i me (5 s/ di v ) 03023-b - 043 volta ge ( 5 v/d i v) v sy = 13v r l = 600 ? f i g u re 44. u n it y g a in f o l l ower r e s p on s e to 2 0 v , 50 k h z i n put sig n al
ad8627/ad8626/ad 8625 rev. b | page 15 of 20 minimizing inpu t cur r ent the ad862x is gua r a n tee d t o 1 pa max in p u t c u r r en t wi t h a 1 3 v supply volt age a t ro om te m p e r a t u r e. c a re f u l a tte n t i o n to h o w t h e am plif i e r is us e d w i l l ma in t a i n o r p o ssi b l y b e t t er t h is p e r f o r ma n c e . th e am plif ier s op era t i n g t e m p er a t ur e sh o u l d b e k e pt as lo w as p o ssi b le. l i k e o t her jfet in p u t am plif iers, t h e ad862x s in p u t c u r r en t do u b les f o r ev er y 10c r i s e in j u n c t i o n t e m p er a t ur e , as i l l u str a te d in f i g u r e 8 . o n -chi p p o w e r dis s i p a t ion ra is es t h e de vic e o p era t i n g t e m p era t ur e , ca using a n i n cr e a s e in in p u t c u r r en t. r e d u cin g su p p ly v o l t a g e t o c u t p o w e r dissi p a t ion r e d u ces the ad862x s in p u t c u r r en t. h e a v y o u t p u t lo ads can a l s o in cr e a s e ch i p t e m p era t ur e; ma in t a in in g a mini m u m lo ad r e sis t a n c e o f 1 k? is r e co mm ended . the ad862x is desig n e d f o r mo un tin g on pc bo a r ds. m a in ta in i n g p i coa m pe r e r e so l u t i o n in th ose en vi r o n m en t s r e q u ir es a lo t o f ca r e . b o t h t h e b o a r d a nd t h e am plif ier s p a cka g e ha v e f i ni t e r e sis t an ce . v o l t a g e dif f er ences b e tw e e n t h e in p u t p i n s an d o t h e r p i ns as wel l as pc b o a r d m e t a l t r aces m a y ca us e p a ras i t i c c u r r en ts la rg er t h a n t h e ad862 x s in p u t c u r r en t, u n l e ss sp e c ia l pre c a u t i ons are t a k e n. f o r p r op e r b o ard l a you t t o en s u r e t h e b e s t r e s u l t , r e fer t o t h e ad i w e bsi t e fo r p r o p er la yo u t s e mina r ma ter i a l . t w o co mm on m e t h o d s o f minim i zi ng p a rasi tic le aka ges tha t sh o u ld b e us e d a r e gu a r din g o f the in p u t lin e s and main t a inin g ade q u a t e in su l a t i on r e sist a n ce . c o n t a m ina n ts such as s o lder f l ux o n t h e b o a r d s s u r f ace a nd t h e am p l i f i e r s p a ck age c a n g r e a t l y re d u c e t h e i n su l a t i on re s i st a n c e bet w een t h e in p u t p i n a n d tra c es wi th s u p p l y o r s i gn al v o l t a g e s . b o t h t h e p a ck a g e a nd t h e b o a r d m u st b e k e p t cle a n and dr y . pho t o d io de preamp lifier ap pli c atio n the lo w in p u t c u r r en t a nd o f fs et v o l t a g e l e v e l s o f th e ad862x, t o get h er wi t h i t s lo w v o l t a g e n o is e , ma k e t h is am plif ier a n exce l l en t ch o i ce fo r p r e a m p lif i ers us e d in s e n s i t i v e ph o t o d io de a p plic a t ion s . i n a ty p i ca l ph o t o v ol t a ic p r e a m p ci r c ui t, sh own i n f i gur e 45, t h e ou t p ut o f t h e am plif ier is e q ua l to (p)rf r id(rf) v p out ? = ? = w h er e: id = p h o t o d io de signal c u r r en t (a) r p = phot o d i o d e s e ns i t iv it y ( a / w ) r f = val u e o f t h e fe e d b a ck r e sis t o r , in ? p = lig h t p o w e r in ci den t t o ph o t o d io de sur f ace , in w the am plif ier s i n p u t c u r r en t, i b , c o n t r i b u t e s a n o u t p u t v o l t a g e er r o r p r o p o r t i o n al t o t h e v a l u e o f t h e fe e d b a ck r e sis t o r . th e o f fs et v o l t a g e er r o r , v os , ca us es a smal l c u r r en t er r o r d u e t o t h e p h o t o d i o de s f i ni t e sh un t r e si s t a n ce , r d . the r e s u l t in g ou t p ut v o l t a g e er r o r , v e , i s e q u a l t o ) rf(i v r r v b os d f e + ? ? ? ? ? ? ? ? + = 1 a s h u n t r e sis t ance o n t h e o r der o f 100 m? is typ i cal f o r a smal l photo d io d e . res i st anc e r d is a j u n c t i on r e sist ance t h a t ty p i c a l l y dr o p s b y a fac t or o f tw o f o r ev er y 10c r i s e in t e m p er a t ur e . i n th e ad862x, both the o f fs et v o l t a g e and dr if t a r e lo w , whic h h e l p s minimize t h es e er r o rs. w i t h i b val u es o f 1 pa an d v os of 50 mv , v e fo r f i gur e 45 is v e r y n e g l ig ib le . a l s o , t h e cir c ui t in f i g u r e 45 res u l t s in an s n r va l u e o f 95 db fo r a s i g n a l b a ndwid t h o f 30 kh z. 03023-b - 044 r d 100m ? c4 15pf i b i b v os c f 5pf r f 1.5m ? output ad8627 photodiode f i gure 45. a photo d iod e mod e l sh o w i n g dc e rror outpu t am plifier for digi tal-to- a nalog converters m a n y sys t e m de sig n ers us e am plif iers as b u f f ers o n the o u t p u t o f a m plif iers t o in cr e a s e t h e d a c s ou t p u t dr ivi n g ca p a b i l i ty . t h e h i g h r e so l u ti o n curr e n t o u t p u t d a c s n eed h i gh p r eci s i o n a m plif iers o n t h eir o u t p ut as c u r r en t t o v o l t a g e co n v er t e rs (i/v) . a d d i t i ona l ly , m a n y d a c s op e r a t e w i t h a s i ng l e su p p ly of 5 v . i n a sin g le- s u p ply a p plic a t ion, s e le c t io n o f a sui t a b le o p a m p m a y b e m o r e dif f i c u l t b e ca us e t h e o u t p u t s w in g o f t h e a m plif ier do es n o t usu a l l y in clude t h e nega t i ve ra i l , in t h is cas e a g nd . this ca n r e su l t in s o m e deg r a d a t io n o f t h e d a c s sp e c if ie d p e r f o r m- a n c e un less t h e a p plic a t ion do e s n o t us e c o des n e a r zer o . t h e s e le c t e d o p am p n e e d s t o ha ve ver y l o w o f fs et v o l t a g efo r a 14-b i t d a c, th e d a c ls b is 30 0 v wi th a 5 v r e f e r e n c et o e l imina t e t h e n e e d fo r o u t p ut o f fs et t r im s. i n p u t b i as c u r r en t shou l d a l s o b e v e r y low b e c a u s e t h e b i as c u r r e n t m u l t i p l i e d b y t h e d a c o u t p u t im p e dan c e (ab o u t 10 k? i n s o m e cas e s) adds t o t h e zer o co de er r o r . r a i l - t o - r a i l i n p u t and o u t p u t p e r f o r manc e i s d e s i re d. f o r f a st s e tt l i n g , t h e sl e w r a te of t h e op am p s h ou l d n o t i m p e de t h e s e t t ling t i m e o f t h e d a c. o u t p u t im p e dan c e of t h e d a c is co nst a n t an d co de i ndep e n d e n t, b u t i n o r der to mini mi ze ga i n e r r o rs, t h e in p u t im p e d a n c e o f t h e o u t p ut a m p l if ier sh o u ld b e as hig h as p o s s i b le . the ad862x, wi t h v e r y hig h i n p u t im p e dan c e, i b o f 1 p a , a n d f a s t s l e w r a t e , i s a n i d e a l a m plif ier fo r t h es e ty p e s o f a p plica t ion s . a ty p i ca l co nf igura t ion wi t h a p o p u la r d a c is sh o w n in f i gur e 46. i n t h es e s i t u a t io n s , t h e am plif ier ad ds an ot h e r t i me co nst a n t t o t h e s y ste m , i n cre a s i ng th e s e t t lin g tim e o f th e o u t p u t . th e ad862x, wi t h 5 mh z o f b w , hel p s i n achi e v i n g a f a st er ef fe c t i ve s e t t l i n g t i me o f t h e c o m b i n e d d a c and a m pl i f ier .
ad8627/ad8626/ad 8625 rev. b | page 16 of 20 03023-b - 045 ad5551/ad5552 ad8627 dgnd *ad5552 only v dd v reff *v re f s * out sclk din cs agnd 5v 2.5v unipolar output l d ac* 0.1 f 10 f 0.1 f serial interface 5v f i g u re 46. u n ipol ar o u t p ut i n a p p l ic a t io n s wi t h f u l l 4-q u adra n t m u l t i p l y ing ca p a b i li ty o r a b i p o la r o u t p u t s w in g, t h e cir c ui t in f i gur e 47 can b e us ed . i n t h is cir c ui t, t h e f i rst a nd s e cond a m plif iers p r o v ide a t o t a l ga i n o f 2, whic h in cr eas e s the o u t p u t v o l t a g e s p an t o 20 v . b i asin g t h e ext e r n al a m plif i e r wi t h a 10 v of fs et f r o m t h e r e fer e n c e v o l t a g e re su l t s in a f u l l 4 - qu a d r a n t m u lt i p ly ing c i rc u i t. 03023-b - 046 one channel ad5544 1/2 ad8626 digital interface connections omitted for clarity v ss a gnd fa gnd x v dd v ref xr fb x adr01 vref 10v 1/2 ad8626 ?13v +13v ?10v < v out < +10v 10k ? 5k ? 10k ? v out f i g u re 47. 4- q u adr a nt m u lt iply ing a p plic at i o n c i rcu i t eight-pole sallen key low-pass f i lter the ad862x s hig h in p u t im p e da n c e an d dc p r e c isio n ma k e i t a g r e a t s e le c t ion fo r ac t i v e f i l t ers. d u e t o t h e v e r y lo w b i as c u r r en t o f th e ad862x, hig h val u e r e sis t o r s ca n be us e d t o co n s tr uc t lo w f r eq uen c y f i l t ers. th e ad862x s p i co a m p-l e v e l in p u t c u r r en ts co n t r i b u t e minimal dc er r o rs. f i gur e 49 s h o w s a n exa m p l e , a 10 h z , 8-p o le sa l l en k e y f i l t er co n s tr uc t e d using th e ad862x. dif f er en t n u m b ers o f t h e ad86 2x ca n b e us e d dep e n d in g on t h e desir e d r e sp o n s e , w h ich is sh o w n i n f i gur e 48. th e hig h val u e used f o r r1 min i mizes in teractio n wi t h sign al so ur ce r e s i s t a n ce . p o l e p l a c em en t in thi s v e r s i o n o f th e f i l t e r m i n i m i z e s t h e q as s o c i a t e d w i t h t h e lo w e r p o le s e c t io n o f t h e f i l t er . thi s el i m i n a t e s a n y p e a k i ng of t h e noi s e c o n t r i but i on of re s i stor s i n t h e p r e c e d in g s e c t io n s , minimi zin g t h e in h e r e n t o u t p u t v o l t a g e n o is e o f t h e f i l t e r . 03023-b - 047 v2 v4 v3 v1 frequency (hz) volta g e ( v ) 0.1 0 0.4 0.8 1.2 1 1 0 100 1k f i g u re 48. f r equen c y r e s p ons e o u t p u t at d i f f e r e nt st ag e s of the l o w - p a ss f i lter
ad8627/ad8626/ad 8625 rev. b | page 17 of 20 03023-b - 048 v in v dd v ee r1 162.3k ? r2 162.3k ? 3 2 11 1 4 u1 r3 25k ? c2 96.19 f d d v3 r10 191.4k ? r5 191.4k ? u2 r4 25k ? c4 69.14 f d r11 286.5k ? r7 286.5k ? u3 r6 25k ? c6 30.86 f d r12 815.8k ? r9 815.8k ? u4 r8 25k ? c8 3.805 f d c1 100 f c3 1/4 ad8625 1/4 ad8625 1/4 ad8625 1/4 ad8625 100 f c5 100 f c7 100 f v1 v2 v3 v4 f i gur e 4 9 . 10 hz , 8 - p o le s a ll e n k e y l o w - p a ss f i lt e r
ad8627/ad8626/ad 8625 rev. b | page 18 of 20 outline dimensions compliant to jedec standards mo-203aa 2. 0 0 b s c 0. 30 0. 15 0 . 1 0 m a x 1. 0 0 0. 9 0 0. 7 0 sea t i n g p l ane 1. 10 m a x 0. 2 2 0. 0 8 0. 46 0. 36 0. 26 3 54 12 pin 1 2. 1 0 bs c 0. 65 bs c 1. 2 5 bs c 0.10 coplanarit y 8 4 0 f i g u re 50. 5-l e ad p l as t i c su r f ace - m o u n t p a ck ag e [sc 70] (k s-5) di me nsio ns sho w n i n mi ll im e t e r s 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 51. 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) 0.80 0.60 0.40 8 0 4 85 4.90 bsc pin 1 0.65 bsc 3.00 bsc seating plane 0.15 0.00 0.38 0.22 1.10 max 3.00 bsc coplanarity 0.10 0.23 0.08 compliant to jedec standards mo-187aa f i g u re 52. 8-l e ad m i ni s m al l o u t l ine p a ck ag e [m sop ] (rm-8) di me nsio ns sho w n i n mi ll im e t e r s 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 coplanarity 0.10 14 8 7 1 6.20 (0.2441) 5.80 (0.2283) 4.00 (0.1575) 3.80 (0.1496) 8.75 (0.3445) 8.55 (0.3366) 1.27 (0.0500) bsc seating plane 0.25 (0.0098) 0.10 (0.0039) 0.51 (0.0201) 0.31 (0.0122) 1.75 (0.0689) 1.35 (0.0531) 8 0 0.50 (0.0197) 0.25 (0.0098) 1.27 (0.0500) 0.40 (0.0157) 0.25 (0.0098) 0.17 (0.0067) compliant to jedec standards ms-012ab 45 f i gure 53. 14-l ead standar d s m all o u tline p a ck age [s oi c ] narro w b o dy (r -14) di me nsio ns sho w n i n mi ll im e t e r s a n d (i nc he s) 4.50 4.40 4.30 14 8 7 1 6.40 bsc pin 1 5.10 5.00 4.90 0.65 bsc seating plane 0.15 0.05 0.30 0.19 1.20 max 1.05 1.00 0.80 0.20 0.09 8 0 0.75 0.60 0.45 coplanarity 0.10 compliant to jedec standards mo-153ab-1 f i gure 54. 1 4 -l ead thin shr i nk s m a l l o u tline p a ckage [ t ssop ] (ru - 14) di me nsio ns sho w n i n mi ll im e t e r s
ad8627/ad8626/ad8625 rev. b | page 19 of 20 ordering guide model temperature range package descri ption package option branding ad8627aks-reel C40c to +85c 5-lead sc70 ks-5 b9a ad8627aks-reel7 C40c to +85c 5-lead sc70 ks-5 b9a AD8627AKS-R2 C40c to +85c 5-lead sc70 ks-5 b9a ad8627ar C40c to +85c 8-lead soic r-8 ad8627ar-reel C40c to +85c 8-lead soic r-8 ad8627ar-reel7 C40c to +85c 8-lead soic r-8 ad8626arm-reel C40c to +85c 8-lead msop rm-8 bja ad8626arm-r2 C40c to +85c 8-lead msop rm-8 bja ad8626ar C40c to +85c 8-lead soic r-8 ad8626ar-reel C40c to +85c 8-lead soic r-8 ad8626ar-reel7 C40c to +85c 8-lead soic r-8 ad8625aru C40c to +85c 14-lead tssop ru-14 ad8625aru-reel C40c to +85c 14-lead tssop ru-14 ad8625ar C40c to +85c 14-lead soic r-14 ad8625ar-reel C40c to +85c 14-lead soic r-14 ad8625ar-reel7 C40c to +85c 14-lead soic r-14
ad8627/ad8626/ad 8625 rev. b | page 20 of 20 notes ? 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 . c03023-0-1/04( b)

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