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low power, high output current differential amplifier ad8390 fea t ures voltage fee d back amplifier ideal for adsl and adsl2+ ce ntral office (co ) and customer premises eq uipment (cpe) applicati o ns enables high current di fferen t ial applications low power ope r ation: single- or dual- p ower supply operation from 10 v ( 5 v) up to 24 v ( 12 v) 4 ma total qui e scent supply current for full power adsl and a d sl2+ c o applications adjustable sup p ly current to minimize power consumption high output vo ltage and curre nt drive: 400 ma peak o u tput dri v e c u r r ent 44.2 v p-p diff e r ential output voltage low d istortion: C82 dbc @ 1 m hz second har m onic C91 dbc @ 1 m hz third harmonic high speed: 300 v/s differ e ntial sl ew rate applic a t io ns adsl/adsl2+ co and cpe lin e driv er xdsl line dri v e r high current di fferential amplifier gener a l description the ad8390 is a hig h o u t p u t c u r r en t, lo w p o w e r co n s um p t io n dif f er en t i a l a m plif ier . i t is p a r t ic u l a r ly w e l l sui t e d fo r t h e ce n t ra l o f f i ce dr i v er in ter f ace in d i g i t a l subs cr ib er li n e s y st em s such as ads l and adsl2+. th e dr i v er is ca p a b l e , in f u l l b i as o p er a t io n, o f p r o v idin g 24. 4 db m o u t p u t p o w e r in t o lo w r e sis t a n ce lo ads, en o u g h t o p o w e r a 20.4 dbm li ne , w h i l e com p e n s a t i n g fo r los s es d u e t o h y b r id i n s e r t io n, t r a n sfo r m e r ins e r t io n, and b a ck t e r m i- na tion r e sis t o r s. the ad8390 f u l l y dif f er en tial am p l if ier is a v ail a b l e in a t h er - mal l y enhan c e d le ad f r a m e chi p s c ale p a cka g e ( l fcs p -16) and a 16-le ad qsop /ep . sig n if ican t co n t r o l a nd f l exi b i l i t y in b i as c u r r en t ha v e be en desig n e d in to th e ad8390. the f o ur p o w e r m o de s a r e co n t rol l e d b y tw o dig i t a l b i t s , pw d n (1,0) , w h i c h p r o v ide t h r e e le vels o f dr i v er b i as an d on e p o w e r e d-down st a t e. in a d d i t i o n , t h e i ad j p i n ca n b e us e d fo r f i n e q u ie s c en t c u r r en t tr immin g t o t a il o r th e p e r f o r ma n c e o f t h e ad8 390. pin c o nfig ur a t ions 03600-0-001 +in dgnd nc = no connect nc nc nc nc nc i adj v ocm pwdn0 pwdn1 ?in ?out v ee v cc +out 1 4 12 13 16 8 5 9 figur e 1. 4 mm 4 mm l f c s p c h ip s c a le p a cka g e 03600-0-002 vocm nc +in pwdn1 pwdn0 ?i n nc dgnd nc nc = no connect ?out nc v ee v cc nc +out i adj 16 1 9 8 figur e 2. 1 6 - l ea d q s op /ep p a cka g e t h e l o w p o we r c o nsu m pt i o n , h i g h output c u r r e n t , h i g h output volt age s w i n g , a n d rob u st t h e r m a l p a ck ag i n g e n abl e t h e a d 8 3 9 0 t o be us e d as t h e cen t ral o f f i ce l i ne dr i v er in ads l , ads l 2+, a nd p r o p r i et a r y xds l sy st ems, as w e l l as in o t her hig h c u r r en t a p pli c a t ion s r e quir in g a dif f er en t i a l am plif ier . rev. b 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 .
ad8390 r e v. b | pa ge 2 o f 1 6 table of contents s p e c if ic a t io n s ..................................................................................... 3 ab s o l u t e m a x i m u m r a t i n g s ............................................................ 5 t y p i cal th er ma l p r o p er ties ............................................................. 5 es d c a u t io n .................................................................................. 5 t y p i c a l p e rf o r m a n c e ch a r a c t e ris t i c s ............................................. 6 the o r y o f o p era t io n ........................................................................ 9 a p plica t ion s ....................................................................................... 9 cir c ui t d e f i ni t i o n s ....................................................................... 9 ana l y z in g a b a s i c a p plic a t io n c i r c ui t ....................................... 9 s e t t in g t h e c l os e d - l o o p gain .................................................... 9 c a l c u l at i n g inp u t imp e d a n c e ..................................................... 9 s e t t in g t h e o u t p u t c o mm o n - m o d e v o l t a g e .......................... 10 p o w e r - d o w n f e a t ur es and t h e i ad j pin ................................... 10 pwd n pin s ............................................................................. 10 ads l and adsl2+ a p plica t io ns ......................................... 10 ads l and adsl2+ a p plica t io ns cir c ui t ............................ 10 mu l t i t o n e po w e r r a t i o ( m t p r ) ............................................... 11 l a yo u t , gr o u nd in g, and by p a ssi n g .......................................... 12 p o w e r dissi p a t i o n an d t h er ma l m a na ge m e n t ....................... 12 o u t l in e di m e n s io n s ....................................................................... 13 or der i n g g u ide .......................................................................... 13 revisi on h i s t or y rev i s i o n b 2/04 C d a ta sh e e t cha n g e d f r o m re v . a t o re v . b . c h a n g e d p u b c o de .......................................................................... 16 rev i s i o n a 1/04 C d a ta sh e e t cha n g e d f r o m re v . s p 0f t o re v . a. a dde d det a ile d des c r i p t io n o f pr o d uc t ............................ u n iv ers a l u p da t e d o u t l ine dim e n s io ns ....................................................... 13
ad8390 rev. b | page 3 of 16 specifications v s = 12 v or +24 v, r l = 100 ? , g = 10, pwdn = (1,1), i adj = nc, v ocm = float, t a = 25c, unless otherwise noted. 1 , 2 table 1. parameter conditions min typ max unit dynamic performance C3 db small signal bandwidth v out = 0.2 v p-p, r f = 10 k? 40 60 mhz large signal bandwidth v out = 4 v p-p 25 40 mhz peaking v out = 0.2 v p-p 0.1 db slew rate v out = 4 v p-p 300 v/s noise/distortion performance second harmonic distortion f c = 1 mhz, v out = 2 v p-p C82 dbc third harmonic distortion f c = 1 mhz, v out = 2 v p-p C91 dbc multitone power ratio (26 khz to 1.1 mhz) z = 100 ?, p = 19.8 dbm, crest factor (cf) = 5.4 line line C70 dbc multitone power ratio (26 khz to 2.2 mhz) z = 100 ?, p = 19.8 dbm, crest factor (cf) = 5.4 line line C65 dbc voltage noise (rti) f = 10 khz 8 nv/hz input current noise f = 10 khz 1 pa/hz input characteristics rti offset voltage (v os,dm(rti) ) v +in C v Cin , v ocm = midsupply C3.0 1.0 +3.0 mv rti offset voltage (v os,dm(rti) ) v +in C v Cin , v ocm = float C3.0 1.0 +3.0 mv input bias current C4.0 C7.0 a input offset current C0.35 0.05 +0.35 a input resistance 400 k? input capacitance 2 pf common-mode rejection ratio (?v os,dm(rti) )/(?v in,cm ) 58 64 db output characteristics differential output voltage swing ?v out 43.8 44.2 44.6 v output balance error (?v os,cm )/?v out 60 db linear output current r l = 10 ?, f c = 100 khz 400 ma worst harmonic = C60 dbc output common-mode offset (v +out + v Cout )/2, v ocm = midsupply C75 35 +75 mv output common-mode offset (v +out + v Cout )/2, v ocm = float C75 35 +75 mv power supply operating range (dual supply) 5 12 v operating range (single supply) +10 +24 v total quiescent current pwdn1, pwdn0 = (1,1); i adj = v ee 5.2 6.5 ma (1,0); i adj = v ee 3.8 5.0 ma (0,1); i adj = v ee 2.5 3.5 ma (0,0); i adj = v ee 0.57 1.0 ma total quiescent current pwdn1, pwdn0 = (1,1); i adj = nc 10.0 11.0 ma (1,0); i adj = nc 6.7 8.0 ma (0,1); i adj = nc 3.8 5.0 ma (0,0); i adj = nc 0.67 1.0 ma power supply rejection ratio ?v os,dm /?v s , ?v s = 1 v, v ocm = midsupply 70 76 db pwdn = 0 (low logic state) 1.0 v pwdn = 1 (high logic state) 1.6 v v ocm to v out specifications input voltage range C11.0 to +10.0 v input resistance 28 k? v ocm accuracy ?v out,cm /?v ocm 0.996 1.0 1.004 v/v 1 v ocm bypassed with 0.1 f capacitor. 2 see test circuit, . figure 3
ad8390 rev. b | page 4 of 16 specifications v s = 5 v or +10 v, r l = 100 ?, g = 10, pwdn = (1,1), i adj = nc, v ocm = float, t a = 25c, unless otherwise noted. 1 , 2 table 2. parameter conditions min typ max unit dynamic performance C3 db small signal bandwidth v out = 0.2 v p-p, r f = 10 k?, g = 10 40 60 mhz large signal bandwidth v out = 4 v p-p 25 40 mhz peaking v out = 0.2 v p-p 0.1 db slew rate v out = 4 v p-p 300 v/s noise/distortion performance second harmonic distortion f c = 1 mhz, v out = 2 v p-p C82 dbc third harmonic distortion f c = 1 mhz, v out = 2 v p-p C91 dbc voltage noise (rti) f = 10 khz 8 nv/hz input current noise f = 10 khz 1 pa/hz input characteristics rti offset voltage (v os,dm(rti) ) v +in C v Cin , v ocm = midsupply C3.0 1.0 +3.0 mv rti offset voltage (v os,dm(rti) ) v +in C v Cin , v ocm = float C3.0 1.0 +3.0 mv input bias current C4.0 C7.0 a input offset current C0.35 0.05 +0.35 a input resistance 400 k? input capacitance 2 pf common-mode rejection ratio (?v os,dm(rti) )/(?v in,cm ) 58 64 db output characteristics differential output voltage swing ?v out 16.0 16.4 16.8 v output balance error (?v os,cm )/?v out 60 db linear output current r l = 10 ?, f c = 100 khz 400 ma worst harmonic = C60 dbc output common-mode offset (v +out + v Cout )/2, v ocm = midsupply C75 35 +75 mv output common-mode offset (v +out + v Cout )/2, v ocm = float C75 35 +75 mv power supply operating range (dual supply) 5 12 v operating range (single supply) +10 +24 v total quiescent current pwdn1, pwdn0 = (1,1); i adj = v ee 4.5 5.5 ma (1,0); i adj = v ee 3.3 4.0 ma (0,1); i adj = v ee 2.1 3.0 ma (0,0); i adj = v ee 0.43 1.0 ma total quiescent current pwdn1, pwdn0 = (1,1); i adj = nc 8.7 10.0 ma (1,0); i adj = nc 5.8 7.0 ma (0,1); i adj = nc 3.3 4.0 ma (0,0); i adj = nc 0.55 1.0 ma power supply rejection ratio ?v os,dm /?v s , ?v s = 1 v, v ocm = midsupply 70 76 db pwdn = 0 (low logic state) 1.0 v pwdn = 1 (high logic state) 1.6 v v ocm to v out specifications input voltage range C4.0 to +3.0 v input resistance 28 k? v ocm accuracy ?v out,cm /?v ocm 0.996 1.0 1.004 v/v 1 v ocm bypassed with 0.1 f capacitor. 2 see test circuit, . figure 3
ad8390 r e v. b | pa ge 5 o f 1 6 absolute maximum ratings t a bl e 3. p a r a m e t e r r a t i n g supply voltage 13.2 v (26.4 v) v ocm v ee < v ocm < v cc package power dissip a tion ( t j max C t a )/ ja maximum junction temperature (t j max ) 1 5 0 c operating tem p erature range (t a ) C40c to +85c storage temperature range C65c to +150c lead temperature (soldering 10 sec) 300c 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 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 . typical thermal properties t a bl e 4. package typical therm a l resistance ( ja ) 16-lead lfcsp ( c p) jedec 2s2p C 0 airflow paddle soldered to board nine thermal vi as in pad 30.4c/w 16-lead qsop/e p (rc) jedec 1s2p C 0 airflow paddle soldered to board nine thermal vi as in pad 44.3c/w 03600-0-003 r f = 10k ? r g = 1k ? 49.9 ? 49.9 ? r g = 1k ? v in r l,dm = 100 ? r f = 10k ? ad8390 v out,dm figur e 3. ba sic te st c i rcuit 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.
ad8390 r e v. b | pa ge 6 o f 1 6 typical perf orm ance cha r acte ristics d e fa u l t c o ndi t i o n s: v s = 12 v o r +24 v , r l = 100 ?, g = 10, p w d n = (1,1), i ad j = n c , v oc m = f l o a t (b yp as s e d wi th 0.1 f c a pacitor), t a = 25c, unles s o t h e r w is e n o ted . s e e t e s t cir c ui t, f i gur e 3. 25 20 15 10 gain ( d b) 5 0 ?5 ?1 0 1 1 0 100 1000 frequency (mhz) pwdn(1,0) i adj = nc pwdn(0,1) i adj = v ee pwdn(0,1) i adj = nc pwdn(1,0) i adj = v ee pwdn(1,1) i adj = v ee pwdn(1,1) i adj = nc 03600-0-004 figur e 4. smal l sig n al freq uency r e spon se; v s = 12 v , ga in = 1 0 , v ou t = 20 0 mv p - p 25 20 15 10 gain ( d b) 5 0 ?5 ?10 1 1 0 100 1000 frequency (mhz) pwdn(0,1) i adj = v ee pwdn(1,0) i adj = nc pwdn(0,1) i adj = nc pwdn(1,1) i adj = nc pwdn(1,0) i adj = v ee pwdn(1,1) i adj = v ee 03600-0-006 figur e 5. l a r ge s i gn a l freq uency r e spo n se; v s = 12 v , ga in = 1 0 , v ou t = 4 v p- p fe e d through (db) ?75 ?70 ?65 ?60 ?55 ?50 ?45 ?40 ?35 ?30 ?25 ?20 ?15 ?10 1 1 0 100 frequency (mhz) 03600-0-008 figur e 6. s i gna l fee d t hro ugh; p w dn = (0 , 0) frequency (mhz) 30 25 20 15 10 gain ( d b) 5 0 ?5 ?1 0 1 1 0 100 1000 pwdn(1,0) i adj = v ee pwdn(1,1) i adj = v ee pwdn(1,0) i adj = nc pwdn(0,1) i adj = v ee pwdn(1,1) i adj = nc pwdn(0,1) i adj = nc 03600-0-026 figur e 7. smal l sig n al freq uency r e spon se; v s = 5 v , ga in = 5, v ou t = 20 0 mv p- p frequency (mhz) 03600-0-027 25 20 15 10 gain ( d b) 5 0 ?5 ?10 1 1 0 100 1000 pwdn(1,0) i adj = v ee pwdn(1,1) i adj = v ee pwdn(0,1) i adj = v ee pwdn(1,1) i adj = nc pwdn(0,1) i adj = nc pwdn(1,0) i adj = nc figur e 8. l a r ge s i gn a l freq uency r e spo n se; v s = 5 v , ga in = 5, v ou t = 2 v p- p frequency (mhz) outp ut imp e dance ( ?) 0.001 0.01 0.1 1 10 100 0.01 0.1 1 1 0 100 03600-0-020 figur e 9. outp ut im pedanc e vs. fr equ en cy; p w dn = (1, 1 )
ad8390 r e v. b | pa ge 7 o f 1 6 output power (dbm) multitone p o we r ratio (dbc ) ?7 5 ?7 0 ?6 5 ?6 0 ?5 5 ?5 0 12 14 20 18 16 22 crest factor = 5.4 pwdn(1,0) i adj = nc pwdn(0,1) i adj = nc pwdn(1,1) i adj = nc pwdn(1,0) i adj = v ee pwdn(1,1) i adj = v ee pwdn(0,1) i adj = v ee 03600-0-010 fi g u re 10 . m t pr vs . o u tp ut powe r; 97 0 kh z empty bin ( 26 kh z to 1. 1 mh z) output power (dbm) 03600-0-028 900 800 700 600 p o we r cons ump t ion (mw) 500 400 300 12 16 14 18 20 22 pwdn(1,0) i adj = v ee pwdn(0,1) i adj = v ee pwdn(0,1) i adj = nc pwdn(1,1) i adj = v ee pwdn(1,1) i adj = nc pwdn(1,0) i adj = nc crest factor = 5.4 fi g u re 11 . powe r cons ump t i o n vs . o u tput powe r ( i ncludes output po we r delivered to load) frequency (mhz) 03600-0-029 ?5 0 total harmonic dis t ortion (dbc ) ?9 0 ?8 5 ?8 0 ?7 5 ?7 0 ?6 5 ?6 0 ?5 5 0.1 1 1 0 pwdn(1,1) i adj = v ee pwdn(1,1) i adj = nc pwdn(0,1) i adj = v ee pwdn(0,1) i adj = nc pwdn(1,0) i adj = v ee pwdn(1,0) i adj = nc fig u re 12 . total harmonic di stortion v s . frequ ency; v s = 12 v , v ou t = 2 v p- p output power (dbm) 03600-0-030 ?4 5 multitone p o we r ratio (dbc ) ?7 0 ?6 5 ?6 0 ?5 5 ?5 0 12 22 20 18 16 14 pwdn(0,1) i adj = v ee pwdn(0,1) i adj = nc pwdn(1,0) i adj = v ee pwdn(1,1) i adj = v ee pwdn(1,1) i adj = nc pwdn(1,0) i adj = nc crest factor = 5.4 fi g u re 13 . m t pr vs . o u tp ut powe r; 1. 75 mh z em pty bin (2 6 kh z to 2. 2 mh z) r load ( ?) 03600-0-031 50 diffe re ntial outp ut s w ing (v ) 0 45 40 35 30 25 20 15 10 5 10 20 30 40 50 60 70 80 90 100 v s = 12v v s = 5v fi g u re 14 . di ffe re ntial o u tput swi n g vs . r loa d frequency (mhz) 03600-0-032 ?5 0 total harmonic distortion (dbc) ?9 0 ?8 5 ?8 0 ?7 5 ?7 0 ?6 5 ?6 0 ?5 5 0.1 1 1 0 pwdn(1,1) i adj = v ee pwdn(1,1) i adj = nc pwdn(0,1) i adj = v ee pwdn(0,1) i adj = nc pwdn(1,0) i adj = v ee pwdn(1,0) i adj = nc fig u re 15 . total harmonic di stortion v s . frequ ency; v s = 5 v, v ou t = 2 v p- p
ad8390 r e v. b | pa ge 8 o f 1 6 i adj series resistor ( ?) s u p p l y curre nt (ma) 2 3 4 5 6 7 8 9 10 11 1 1 0 100 1k 10k 100k 1m pwdn(1,1) pwdn(0,1) pwdn(1,0) 03600-0-016 figur e 1 6 . q u ie scent current vs. i adj re s istor ; v s = 1 2 v time ( s) diffe re ntial outp ut (v ) pw d n pin va lu es ( v ) ?3 ?2 ?1 0 1 2 3 ?0.5 0.5 1.5 2.5 3.5 4.5 5.5 ?0.2 ?0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 output pwdn pins 03600-0-018 fi g u re 17 . powe r-u p ti me ; p w dn = (0, 0 ) to p w dn = (1, 1 ) frequency (hz) volta ge n o ise ( n v/ 1 10 100 10 100 100k 1m 10k 1k 10m 03600-0-014 hz) figur e 1 8 . v o ltage n o ise (r ti) i adj series resistor ( ?) s u p p l y curre nt (ma) 2 1 3 4 5 6 7 8 9 1 1 0 100 1k 10k 100k 1m pwdn(1,1) pwdn(0,1) pwdn(1,0) 03600-0-017 figur e 1 9 . q u ie scent current vs. i adj re s istor ; v s = 5 v time ( s) diffe re ntial outp ut (v ) pw d n pin va lu es ( v ) ?3 ?2 ?1 0 1 2 3 ? 0.5 0.5 1.5 2.5 3.5 4.5 5.5 ?2 0 2 4 6 8 1 0 output pwdn pins 03600-0-019 fi g u re 20 . powe r-down ti me ; p w dn = (1, 1 ) to p w dn = (0, 0 ) frequency (hz) curre nt nois e (pa/ hz) 0.1 1.0 10 100 10 100 1k 10k 100k 1m 10m 03600-0-015 figur e 2 1 . c urr ent n o ise (r ti)
ad8390 r e v. b | pa ge 9 o f 1 6 theory of operation 03600-0-035 a c b 50k ? r g r g 50k ? 56k ? v cc 56k ? v ocm byp +out ad8390 ?out +in i adj pwdn0 r adj pwdn1 dgnd ?in v ee v ee r f r f figur e 2 2 . funct i on al block diag ram the ad8390 is a tr ue dif f er en tial o p era t io nal am p l if ier wi th co mmon-mo d e f e e d bac k . the ad83 90 is f u n c tional l y e q u i valen t to t h re e op am p s a s s h ow n i n fi g u re 2 2 . a m pl i f i e r s a a n d b a c t li k e a st a n d a r d d u a l o p am p i n a n i n v e r t in g conf igura t io n t h a t r e q u ir es fo ur r e sis t o r s t o s e t t h e desir e d ga in. the t h ir d a m pli f ier (c) ma in t a i n s t h e co mm on-mo d e v o l t a g e (v oc m ) a t t h e o u t p u t o f t h e ad8 390. v oc m is in t e r n a l ly gen e r a te d as sho w n i n f i gur e 2 2 . th e com m o n -mo d e fe e d b a ck a m plif ier (c) dr i v es t h e n o ni n v er t i n g ter m ina l s o f a a nd b such t h a t t h e dif f er ence b e tw e e n t h e o u t p ut co mm on- m o d e v o l t a g e a nd v oc m is a l wa y s zer o . this f u n c t i o n a l i t y fo r c es t h e o u t p uts to si t a t mids u p p l y , whic h r e s u l t s in dif f er en t i al o u t p u t s o f ide n tic a l a m p l i t ude an d 180 deg r ees o u t o f p h as e . th e us er als o has th e o p t i o n t o ext e r n al l y dr i v e t h e v oc m p i n as an i n p u t t o s e t t h e dc o u t p ut co mm on- m o d e v o l t a g e . f o r det a i l s, s e e t h e s e t t in g t h e ou t p u t c o mm o n - m ode v o l t a g e secti o n . appli c ations circuit de finitions d i ffer en ti a l vo l t a g e r e fers to t h e dif f er en ce b e twe e n tw o no de v o l t a g es. f o r exa m ple , t h e o u t p u t dif f er en t i al vol t a g e (o r o u t p ut dif f er en t i al - m o d e v o l t a g e) is de f i n e d as ( ) out out dm out v v v ? + ? = (1) v +o ut an d v Co ut r e fer t o t h e v o l t a g es a t t h e +o u t an d Co u t te r m i n a l s w i t h re sp e c t to a c o m m on re fe re nc e. c o mm on - m o d e v o lt ag e r e fers t o t h e a v era g e o f t h e tw o n o de v o l t a g es. th e o u t p u t comm o n - m o d e v o l t a g e is def i n e d as ( ) 2 , out out cm out v v v ? + + = (2) analyzing a basic application circuit the ad8390 us es hig h o p en-lo o p ga in and neg a ti v e f e e d b a c k to fo r c e i t s dif f er en t i al an d commo n - m o d e o u t p ut v o l t a g es i n s u ch a wa y as t o mini mi ze t h e dif f er en t i al an d commo n - m o d e er r o r v o l t a g es. th e di f f er en t i al er r o r v o l t a g e is def i n e d as t h e v o l t a g e b e t w een t h e di f f e r en t i al in p u t s la b e le d +in a n d Cin in f i gur e 23. f o r mo st p u r p o s e s , t h is vol t age c a n b e assu me d to b e ze ro . simi l a rl y , t h e di f f er en ce b e tw e e n t h e ac t u al o u t p u t co mm on- m o de v o l t a g e and t h e v o l t a g e a p plie d t o v oc m ca n als o b e a s s u m e d t o be ze r o . s t a r ti n g f r o m th ese tw o a s sum p ti o n s, a n y ap p l i c at i o n c i r c u i t c a n b e a n a l y z e d . 03600-0-022 r f ? out +out +in ?i n r g v ocm r g r l,dm v out,dm + ? v in,dm ? + r f figur e 2 3 . basi c ap pl ications c i r c uit (i adj pi n not conne ct e d , and pw dn0 and pw dn1 he ld hi gh) setti ng th e closed-loop g a in the dif f er en t i al -mo d e ga i n o f t h e cir c ui t i n f i g u r e 23 ca n b e des c r i b e d b y g f dm in dm out r r v v = (3) calculating input impedance the i n p u t i m p e dan c e o f t h e circ ui t in f i gur e 23 b e tw e e n t h e in p u ts (v +i n an d v ?in ) is sim p l y g dm in r r = 2 , (4)
ad8390 rev. b | page 10 of 16 setting the output common-mode voltage by design, the ad8390s v ocm pin is internally biased at a voltage equal to the midsupply point (average value of the voltages on v cc and v ee ), eliminating the need for external resistors. however, the high impedance nature of the v ocm pin allows the designer to force it to a desired level with an external low impedance source. it should be noted that the v ocm pin is not intended for use as an ac signal input. the three configurations for the v ocm pin are floating with a single supply, floating with dual supplies, and forcing the pin with an external source. if not externally forcing the v ocm pin, the designer must decouple it to ground with a 0.1 f capacitor in close proximity to the ad8390. with dual equal supplies (for example, 12 v) such that the midpoint of the supplies is nominally 0 v, the user may opt to connect the v ocm pin directly to ground, thus eliminating the need for an external decoupling capacitor. power-down features and the i adj pin the ad8390 offers significant versatility in setting quiescent bias levels for a particular application from full on to full off. this versatility gives the circuit designer the flexibility to maxi- mize efficiency while maintaining optimal levels of performance. optimizing driver efficiency while delivering the required signal level is accomplished with the ad8390 through the use of two on-chip power management features: two pwdn pins used to select one of four bias modes, and an i adj pin used for additional power management including fine bias adjustments. pwdn pins two digitally programmable logic pins, pwdn1 and pwdn0, may be used to select four different bias levels (see table 5). these levels start with full power if the i adj pin is not connected. the top bias level can also start at approximately half of full bias, if the i adj pin is connected to v ee or to ground in a single-supply configuration, r adj = 0. the bias level can be controlled with cmos logic levels (high = 1) applied to the pwdn1 and pwdn0 pins alone or in combination with the i adj control pin. the digital ground pin (dgnd) is the logic ground reference for the pwdn1 and pwdn0 pins. pwdn = (0,0) is the power-down mode of the amplifier. the ad8390 exhibits a low output impedance for pwdn1,0 = (1,1), (1,0), and (0,1). however, at pwdn1,0 = (0,0), the output impedance is undefined. the lowest power mode (0,0) of the ad8390 alone may not be suitable for systems that rely on a high impedance off state, such as multiplexing. i adj pin the i adj feature offers users significant flexibility in setting the bias level of the ad8390 by allowing for fine tuning of the bias setting. use of the i adj feature is not required for operation of the ad8390. when i adj is not connected, the bias current in the various power modes is set to approximately 10 ma, 6.7 ma, and 3.8 ma for power modes pwdn1,0 = (1,1), (1,0), and (0,1), respectively, as seen in table 5. setting i adj = v ee for dual- supply operation (or grounding the i adj pin for single-supply operation) cuts the bias setting approximately in half for each mode. a resistor (r adj ) between i adj and ground for single-supply operation, or i adj and v ee for dual-supply operation, allows fine bias adjustment between the bias levels pre-set by the pwdn pins. figure 16 and figure 19 depict the effect of different r adj values on setting the bias levels. table 5. pwdn code selection guide pwdn1 pwdn0 r adj (? ) i q (ma) 1 1 10.0 1 0 6.7 0 1 3.8 0 0 0.67 1 1 0 5.2 1 0 0 3.8 0 1 0 2.5 0 0 0 0.57 adsl and adsl2+ applications the ad8390 line driver amplifier is an efficient class ab amplifier that is ideal for driving xdsl signals. the ad8390 may be used for driving adsl or adsl2+ modulated signals in either direc- tion: upstream from customer premises equipment (cpe) to the central office (co) or downstream from co to cpe. adsl and adsl2+ applications circuit increased co port density has made driver power efficiency an important requirement in adsl and adsl2+ systems. the largest impact on efficiency is due to the need for back termina- tion of the driver. in the simplest case, this is accomplished with a pair of resistors, each equal to half the reflected line impedance, in series with the outputs of the differential driver. in this scenario, half the transmitted power is consumed by the back termination resistors. this results in the need for higher turns ratio transformers, which attenuate the receive signal, tend to be more lossy, and increase current requirements of the driver, effectively reducing headroom because the output devices can no longer swing as close to the rail. to solve this problem, it is common practice to use a combination of negative and positive feedback to synthesize the output impedance, thus decreasing the required ohmic value of the back termination. overall efficiency is improved because less power is wasted in the back termination and a lower turns ratio transformer can be used without the need for increased supply rails. the application circuit in figure 24 depicts such an approach, where the positive feedback, negative feedback, and back termination are provided with r2, r3, and rm, respectively.
ad8390 rev. b | page 11 of 16 03600- 0- 036 p w dn1 p w dn0 r m r l v out,dm + ? ?out +out r m r3 r2 r1 r1 r3 0.1 f i adj r adj r2 1:n 10 f 0.1 f v cc +in v ocm ?in 10 f 0.1 f 0.1 f v ee figur e 2 4 . adsl/ad sl2+ ap plication c i r c uit r e f e rri n g t o f i g u r e 2 4 , th e f o ll o w in g d e sc ri be s h o w t o c a l c ula t e t h e r e sis t o r val u es n e ce s s a r y t o ob t a i n t h e desire d i n p u t im p e d- a n c e , ga in, and o u t p ut im p e dance. the dif f er en t i al in p u t im p e dan c e t o t h e c i r c ui t i s sim p l y 2 r1 . as s u c h , r1 is ch o s en b y t h e de sig n er to y i el d t h e desir e d i n p u t im p e d a n c e . w h en s y n t h e si zin g t h e o u t p u t i m p e dance , a fac t o r k is in t r o d uc e d , w h i c h is us e d t o ex p r es s t h e r a t i o of t h e n e ga t i v e f eed ba ck r e s i s t o r t o th e pos i ti v e f eed ba ck r e s i s t o r b y r2 r3 k = ? 1 (5) k is als o us ed , alo n g wi th t h e t u r n s ra tio n, in def i nin g t h e val u e o f t h e b a ck t e r m ina t io n r e sisto r s r m . c o m m o n l y u s e d v a l u e s f o r k a r e 0. 1 t o 0. 25 . a k v a lu e of 0 . 1 wou l d re su lt i n b a c k te r m in a t ion r e sis t o r s t h a t a r e o n l y 1/10 as l a rg e as t h os e i n t h e si m p les t cas e des c r i b e d ab o v e. l o w e r va l u es o f k re su lt i n g r e a te r amou n t s of p o si t i v e fe e d b a ck. th er efo r e , val u es m u ch lo w e r t h a n 0.1 can l e a d to i n s t abi l it y and are ge ne r a l l y not re c o m m e n d e d. 2 2 n r k r l m = (6) this fac t o r ( k ), alo n g wi th r1 , r m , a nd t h e desi r e d ga in ( a v ), is th en used t o cal c ul a t e t h e n e ce s s a r y v a l u e s f o r r3 an d r2 . ( ) m m v v v r k r k r1 a r1 a k r1 a r3 ? + + = 2 (7) th e us uall y s m all val u e f o r r m al l o w s a sim p li f i e d a p p r o x i m a t i o n fo r r3 . v a k r1 r3 ? 2 (8) k r3 r2 ? = 1 (9) on ce r m , r3 , a nd r2 a r e com p ut e d , t h e clos es t 1% r e sis t o r s can be ch osen a n d t h e ga in r e ch eck e d w i t h th e f o ll o w i n g eq ua ti o n : () r1 r3 r2 r2 k r r3 r2 a m v ? + + = (10) t a b l e 6 sh o w s a co m p a r is o n o f t h e r e s u l t s usin g t h e exac t va l u es, t h e si m p lif i e d a p p r o x ima t ion, and t h e clos es t 1 % r e sis t o r val u e s . in t h i s e x a m p l e , r1 , a v , a n d k wer e c h os en t o b e 1.0 k?, 10, a n d 0.1, r e s p ec ti v e l y . i t s h o u ld b e n o t e d th a t d e cr ea sin g th e v a l u e o f th e b a c k t e rm i - na t i on r e sis t o r s a t t e n u a t es t h e re cei v e sig n al b y a p p r o x ima t e l y 1/k. h o w e v e r , ad van c es i n lo w n o is e r e c e i v e am plif iers p e r m i t k val u es as smal l as 0.1 t o b e co mm o n l y us e d . t h e l i ne i m p e d a nc e, tu r n s r a t i o , and k f a c t or s p e c i f y t h e output v o l t a g e and c u r r en t r e q u ir em en ts f r o m t h e ad8390. t o accom- m o da t e hig h er cr es t fac t o r s o r lo w e r s u p p l y ra i l s, t h e t u r n s ra t i o , n , ma y ha v e t o be in c r eased . s i n c e hi g h e r t u r n s ra ti os a n d s m all e r k fac t o r s b o t h a t t e n u a t e t h e r e ce i v e sig n al , a l a rg e in cr e a s e i n n ma y r e q u ir e an in cr e a s e i n k t o ma in t a i n t h e de sir e d n o i s e p e r f o r ma n c e . a n y p a r t ic u l a r desig n p r o c es s r e quir es t h a t t h es e tra d e - o f fs be v i si t e d . t a bl e 6. resi st or s e l e c t i o n coonent act alue s roiate calculation standard 1 resistor alue s r1 (? ) 1000 1000 1000 r2 (? ) 2246.95 2222.22 2210 r3 (? ) 2022.25 2000 2000 r m (?) 5 5 4.99 actual a v 1 0 . 0 0 0 9 . 8 8 9 1 0 . 1 3 8 actual k (eq. 5) 0.1 0.1 0.095 multitone power ratio ( m tpr ) m u l t i t o n e p o w e r ra tio is a co mm o n l y use d f i gur e o f m e r i t tha t xds l desig n ers us e t o h e l p des c r i be syst em p e r f o r ma n c e . mt p r i s t h e m e a s ur ed de l t a bet w een t h e peak o f a f i ll ed f r e q uen c y b i n and t h e ha r m oni c p r o d uc ts t h a t a p p e a r in an i n t e n t i o n a ll y em p t y f r eq uen c y b i n . f i gur e 25 ill u s t ra t e s th i s p r in ci p l e . the plo t s in f i gur e 10 a nd f i gur e 13 sh o w mtp r p e r f or m a nc e i n v a r i ou s p o we r mo d e s . a l l d a t a we re t a ke n w i t h a cir c ui t wi t h a k-fac t o r o f 0.1, a 1:1 t u r n s ra tio tra n sf o r m e r , a nd a w a vef o rm wi t h a 5.4 pe ak t o a v era g e ra ti o , als o kn o w n a s t h e cr es t fac t o r (cf). 03600-0-033 ? 70dbc 10db/div center 431.25khz span 10khz 1khz/div figur e 2 5 . mt p r me a s ureme nt
ad8390 rev. b | page 12 of 16 t o ob ta in o p tim u m th er mal p e r f o r ma n c e f r o m th e ad8390 in ei t h er p a cka g e , i t is es s e n t ial t h a t t h e t h er mal p a d b e s o lder e d t o a g r o u n d plan e wi t h mi nima l t h er ma l r e sist ance. this is p a r - ti cula r l y tr ue f o r d e n s e ci r c ui t de si gn s wi th m u l t i p le i n t e gra t e d cir c ui ts. f u r t h e rm o r e , t h e pcb sh o u ld be desig n ed in s u c h a m a n n e r a s t o d r aw t h e h e at aw a y f r o m t h e i c s . fi g u r e 2 6 i l l u st r a te s t h e re l a t i onsh i p b e twe e n t h e r ma l re s i st anc e ( c / w) a nd co p p er a r e a (mm 2 ) f o r th e ad8390a cp s o lder ed do wn t o a 4-la yer b o a r d w i t h a g i ven cop p er a r e a . layout, gr ounding, and bypassing the f i rs t l a yo u t r e q u ir em e n t is fo r a g o o d s o li d g r o u n d pl an e tha t co v e rs as m u c h o f th e bo a r d a r ea a r o u n d t h e ad8390 as p o ssi b le . t h e o n ly excep t io n t o t h is is t h a t t h e t w o in p u t p i n s shou l d b e ke pt a f e w m i l l i m e t e r s f r om t h e g r ou nd p l a n e, a n d g r ou nd s h ou l d b e re move d f r om i n ne r l a y e r s an d t h e opp o s i t e side o f t h e b o a r d under t h e in pu t t r aces. this mini mi zes t h e s t ra y ca p a c i t a nc e o n t h es e n o de s a nd h e l p s p r es er v e t h e ga i n f l a t n e s s v e rs us f r eq uen c y . f i gur e 26 ca n b e us e d t o h e l p det e r m in e t h e cop p er b o a r d a r e a r e q u ir ed f o r p r o p er th er mal mana g e m e n t o f the ad8390. the p o w e r dis s i p a t io n o f th e ad83 90 ca n be com p u t ed usin g e q ua t i on 11. th is n u m b er can t h e n b e in s e r t e d in t o t h e f o l l ow i n g e q u a t i on to y i el d t h e re qu i r e d ja : the p o we r su p p ly p i ns s h ou l d b e b y p a ss e d as cl o s e as p o ss ibl e t o th e dev i c e o n a gr o u n d p l a n e c o mm o n wi th si gn al gr o u n d . g o o d hig h f r eq uen c y cera mic chi p c a p a ci t o rs sh o u ld be us e d . this b y p a ssing sh o u ld b e don e wi t h a ca p a c i t a nce va l u e o f 0.01 f t o 0.1 f f o r eac h s u p p l y . l o w f r eq uen c y b y p a s s in g shou l d b e prov i d e d w i t h 1 0 f t a n t a l u m c a p a c i tor s f r om e a ch s u p p l y t o sig n al g r o u n d . th e sig n al r o u t in g sh ou ld be s h o r t and dir e c t t o a v oid p a rasi tic ef f e c t s, p a r t ic u l a r l y o n traces co nn ec t e d t o t h e am plif ier in p u ts. w h er e v e r t h er e a r e co m p lem e n t a r y sig n als, a symmetr i cal la yo u t sho u ld be p r o v ide d t o the ext e n t p o ssi b le to m a x i mi ze t h e b a lance p e r f o r ma n c e. w h e n r u nnin g dif f er en t i al sig n als o v er a lo n g dis t an ce , t h e t r ac es o n t h e pcb shou l d b e cl o s e to ge t h e r . w c p t ad8390 rise ja = = (12) w h er e t ris e i s t h e d e l t a f r o m t h e m a xi m u m e x pe ct ed a m b i en t t e m p era t ur e t o t h e hig h es t al lo wa b l e die t e m p er a t ur e . i t is gen e ra l l y r e co m m e n d e d t h a t t h e max i m u m di e tem p era t ur e b e limi ted t o 125c, a nd in n o cas e s h o u l d i t be al lo w e d t o exceed 150c. power diss ipatio n and thermal manageme nt us i n g t h e ja co m p u t ed in e q ua tio n 12, f i gur e 26 ca n be us e d to de t e r m i n e t h e mi nim u m c o pp er a r e a r e q u ire d fo r p r o p er t h er mal dis s i p a t io n o f t h e ad8390. the ad8390 was desig n e d t o be th e m o s t ef f i cien t c l as s ab ads l /ad s l2+ lin e dr i v er a v ail a b l e . f i gur e 11 sh o w s the t o tal p o wer c o nsu m pt ion (d el i ver e d li ne p o wer and p o wer c o nsu m e d ) o f th e ad8390 dr i v in g ads l sig n als a t va r y in g o u t p u t p o w e rs a nd p o w e r m o d e s. t o acc u r a tely deter m ine t h e a m o u n t o f p o w e r dis s i p a t e d b y th e ad839 0, i t is neces s a r y t o s u b t rac t t h e p o w e r de li v e r e d t o th e lo ad , ma tc hin g los s es, and tra n sf o r m e r l o ss e s as fol l ows: cu area (mm 2) 03600-0-034 90 ja (c/ w) 0 20 10 30 40 50 60 70 80 1 100 1000 10 10000 mw losses mw load supply,mw ad8390 p p p p , , ? ? = (11) w h er e: p supp ly , m w i s th e t o tal s u p p l y po w e r i n mw d r a w n b y th e a d 8390. p loa d ,m w i s t h e p o w e r de li v e r e d in t o a 100 twist e d-p a ir lin e in m w . p lo s s e s ,m w i s th e p o w e r d i s s i p a t e d b y th e ma t c h i n g r e si s t o r s a n d th e tra n sf o r m e r i n mw . figur e 2 6 . therma l r esi stance v s . c o pper area w h i l e t h is dis c ussio n fo c u s e s ma in ly o n ad sl a p plic a t ion s , t h e s a me p r emis e c a n b e a p plie d to deter m ini n g t h e p o w e r dissi p a - tio n o f th e ad8 390 in an y a p p l ica t ion.
ad8390 rev. b | page 13 of 16 outline dimensions 16 5 13 8 9 12 1 4 bo t t o m view 2.25 2.10 sq 1.95 0.75 0.60 0.50 0.65 bsc 1. 9 5 b s c 0.35 0.28 0.25 12 max 0. 20 re f seating plane pin 1 indicator top view 4.0 bs c s q 3.75 bs c s q 0.60 max 0.60 max 0.05 max 0.02 nom 0 . 8 0 ma x 0.65 typ pin 1 indicator 1.00 0.85 0.80 coplanarity 0.08 0. 25 m i n compliant to jedec standards mo-220-vggc fig u re 27 . 1 6 - lead le ad frame, chip scale packag e [ l fcsp] (c p - 16) dimen sions show n i n mil limet ers 16 9 8 1 0. 1 9 7 0. 1 8 9 0. 2 3 6 bs c pin 1 0. 1 5 4 bs c sea t i n g p l ane 0. 01 0 0. 00 4 0. 0 1 2 0. 0 0 8 0. 0 2 5 bs c 0. 010 0. 006 0. 0 5 0 0. 0 1 6 coplanarity 0.004 0. 0 6 5 0. 0 4 9 0. 0 6 9 0. 0 5 3 bottom view 0. 0 9 0 0. 0 9 6 top view compliant to jedec standards mo-137 8 0 0. 0 7 7 figur e 2 8 . 16- l e a d s hrink s m a l l out lin e p a cka g e, expo se d p a d [qs op /ep ] (r c - 16) dimen sions show n i n inc h es ordering guide model temperature r a nge package descri ption package option ad8390acp-re el C40c to +85c 16-lead 4 mm 4 mm lfcsp cp-16 13 tape and reel ad8390acp-r2 C40c to +85c 16-lead 4 mm 4 mm lfcsp cp-16 7 tape and reel ad8390acp-re el7 C40c to +85c 16-lead 4 mm 4 mm lfcsp cp-16 7 tape and reel a d 8 3 9 0 a c p - e v a l e v a l u a t i o n boar d l f c s p ad8390arc C40c to +85c 16-lead qsop/ep rc-16 ad8390arc-re el C40c to +85c 16-lead qsop/ep rc-16 13 tape and reel ad8390arc-re el7 C40c to +85c 16-lead qsop/ep rc-16 7 tape and reel ad8390arc-e v a l e v a l u a t i o n boar d q s o p / e p
ad8390 rev. b | page 14 of 16 notes
ad8390 rev. b | page 15 of 16 notes
ad8390 rev. b | page 16 of 16 notes ? 2004 analo g de vices, inc. all rights reserve d . tra d em arks and registered trad emar ks are the prop ert y of th eir respective ow ners c02694-0-2/04( b)

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