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128-position i 2 c compatible digital potentiometer ad5247 features 128-position end-to-end r e s istance 5 k?, 1 0 k?, 50 k?, 10 0 k? ultracompact sc70-6 (2 mm 2.1 mm) packa g e i 2 c ? compatibl e interface full re ad/write of wiper register power-on preset to midscale single supply 2 . 7 v to 5. 5 v low temperature coefficient 4 5 ppm/c low power, i dd = 3 a typical wide operatin g temperature C40c to +125 c evaluation board available applic ati o ns mechanical pot e ntiometer replacement in ne w designs rev. 0 transducer adj u stment of pre ssure, tempera t ure, position, chemical, and optical sensors rf amplifier bi asing lcd brightness and contrast a d justment automotive e l ectronics adjustment gain control and offset a d just ment general overview the ad5247 p r o v ides a com p ac t 2 mm 2.1 mm p a c k a g e d s o l u tio n f o r 128-p o si tio n ad j u s t m e n t a p p l ic a t ion s . this de vice p e r f or ms t h e s a me el e c t r on i c a d j u st me n t f u nc t i on a s a m e ch a n ic a l p o ten t iom e ter o r a va r i a b le r e sist o r . a v ai lab l e in fo ur dif f er en t end-to - e nd r e sist a n c e va l u es (5 k ? , 10 k? , 50 k? , 100 k?), th es e l o w t e m p er a t ur e co ef f i cien t devices a r e ideal f o r hig h acc u rac y and st ab i l i t y va r i a b le r e sist an ce a d j u st m e n t s. the wi p e r s e t t i n gs a r e co n t r o l l a b l e t h r o ug h t h e i 2 c co m p a t ib l e dig i t a l in t e r f ace , whic h can als o be us e d t o r e ad bac k t h e p r es en t w i p e r re g i ste r c o n t ro l word. t h e re s i st anc e b e t w e e n t h e w i p e r a nd ei t h er e nd p o in t o f t h e f i xe d r e sisto r va r i es lin e a r ly wi t h r e s p ect t o t h e digi tal co de tra n sf er r e d i n t o t h e rd a c 1 la t c h. o p era t ing f r o m a 2.7 v t o 5.5 v p o w e r s u p p l y a nd co n s u m in g 3 a al lo ws fo r us a g e in p o r t a b le b a t t er y-o p er a t e d a p plic a t io n s . func tio n a l block di agram i 2 c interface wiper register scl sda gnd v dd a w b 03876-0-001 fi g u r e 1 . 1 no te : the te rms d i gital po te nti ometer, vr, and rda c are us ed inte rchange a bl y in this d o cume nt. 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 . specifications subjec t 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 herwi s e u n der a n y p a t e nt or p a t e nt ri ghts of analog de v i ces. trademarks an d registered tra d ema r ks are the prop erty o f their respective ow ners. one technolog y way, p.o . box 9106, norwood, ma 02062-9106, u.s.a. t e l: 781. 329. 4 700 www.analog.com fax: 781. 326. 87 03 ? 2003 analog de vices, i n c. al l r i ght s r e ser v ed .
ad5247 t a ble of conte n ts e l e t r ial c a r a t e r i s t is5 k? v e rsio n e l e tr ial c a r a t e r i s t is10 k?, 50 k?, 100 k? v e rsio n s 4 ti m i n g c a r a t e r i s t i s 5 k?, 10 k?, 50 k?, 100 k? v e rsio n s 5 a b s o l t e m a im m r a t i n g s t p i al p e r o r ma n e c a r a t e r i s t is 7 t e st cir i t s 11 i 2 c i n ter ae 12 o p era t ion 1 p r og ra mmin g t e v a r i a b le resis t o r 1 p r og ra mmin g t e p o t e n t iom e ter di ier 14 i 2 c c o m p a t i b le 2- i r e s e r i al bs 14 l e e l s i t i n g o r b i ir e t io nal i n t e r ae 15 es d p r o t e t i on 15 t e r m inal v o l t a g e o p era t in g r a n g e 15 m a im m o p e r a t in g c r r en t 15 p o e r - u p s e en e 15 l a o t an p o er s p pl b p a s s in g 1 c o n s t a n t b i as to ret a in resis t an e s e t t in g 1 e al a t i o n b o a r 1 p i n c o n igra t io n an f n t i on d e s r i p t ion s 17 o t l in e dim e n s io n s 18 or er i n g g ie 18 revision history re i s i o n 0 i n i t ial v e r s i o n re 0 page 2 o 2 0
ad5247 electrical characteristics?5 k version table 1. v dd = 5 v 10% or 3 v 10%; v a = + v dd ; C40 c < t a < +12 5 c; unles s ot herwi s e not e d p a r a e t e r b o l c o n d i t i o n s m i n tp 1 m a n i t dc carac tr tcr t at md resistor dierential onlin earit 2 r d r wb , v a = o connect C1.5 0.1 +1.5 b resistor ntegral onlinearit 2 r r wb , v a = o connect C4 0.75 +4 b oinal resi sto r t o lerance 3 r ab C 3 0 + 3 0 % resistance te p erature coeicient r ab t v a = v dd , wiper = o connect 45 ppc r wb r wb code = 000 75 300 dc carac tr tcpt tmtr dvd r md dierential on l inearit 4 d C 1 0 . 1 + 1 b ntegral onlinearit 4 C 1 0 . 2 + 1 b voltage diider teperature coeicient v w t code = 040 15 ppc fullcale rror v wf code = 07f C3 C2 0 b erocale rr o r v w code = 000 0 +1 +2 b rtr trm a voltage range 5 v b, w d v dd v capacitance 6 a c a = 1 m, meas ured to d, code = 040 4 5 p f capacitance 6 w c w = 1 m, meas ured to d, code = 040 6 0 p f coonmode eaage cm v a = v dd 2 1 n a dta p t ad tp t nput ogic ig h v v dd = 5 v 2.4 v nput ogic ow v v dd = 5 v 0.8 v nput ogic ig h v v dd = 3 v 2.1 v nput ogic ow v v dd = 3 v 0.6 v nput current v = 0 v or 5 v 1 a nput capacitance 6 c 5 p f pwr pp power uppl range v dd ra 2 . 7 5 . 5 v uppl current dd v = 5 v or v = 0 v 3 8 a power dissi pati on 7 p d v = 5 v or v = 0 v, v dd = 5 v 40 w power uppl e nsitiit pr v dd = +5 v 10%, code = mids cale 0 . 0 0 3 0 . 0 5 % % damc c aractr t c 6, 8 bandwidth C3 db bw5 r ab = 5 , code = 040 1.2 m t o tal aronic distortion t d w v a = 1 v rs, v b = 0 v, = 1 0 . 0 5 % v w ettling tie t v a = 5 v, 1 b rror band 1 s resistor oise v o ltage densit e wb r wb = 2.5 , r = 0 6 nv 1 tpical s p eci ications repres e nt aera g e read ings at 25c and v dd = 5 v. 2 r e si st o r po si t i on n o n l i n ea ri t error r i s t h e dei a t i o n r o an ideal al u e eas ured betw een the aiu re si s t a n ce a n d t h e i n i u resi st a n ce wi per posi t i on s. r d e a s ure s t h e rela t i e st ep ch a n ge ro i d ea l bet w een succ essi e t a p posi t i on s . pa rt s a r e gua ra n t eed o n o t o n i c. 3 v a = v dd , wiper v w = n o con n e ct . 4 and d are e as ured at v w with the rda c c o n igured a s a p o tentioeter d i id e r s iil ar to a ol t age ou tput da conerter. v a = v dd and v b = 0 v . d s p eci ication l i its o 1 b aiu ar e guarante e d o no to nic o p e r ating co nd itio ns . 5 r e si st o r t e r i n a l s a a n d w h a e n o li i t a t i o n s on po la ri t wi t h respect t o e a ch ot h e r. 6 ua r a n t eed b des i gn a n d n o t sub ect t o pro d uct i on t e st . 7 p d i s ca lcula t e d r o dd v dd . cm l o gi c lee l i n put s resu lt in iniu power d i ss ipation. 8 al l d naic characteris t ics use v dd = 5 v. re. 0 page 3 o 2 0
ad5247 rev. 0 | page 4 of 20 electrical characteristics10 k?, 50 k?, 100 k? versions table 2. v dd = 5 v 10% or 3 v 10%; v a = v dd ; C40c < t a < +125c; unless otherwise noted parameter symbol conditions min typ 1 max unit dc characteristicsrheostat mode resistor differential nonlinearity 2 r-dnl r wb , v a = no connect C1 0.1 +1 lsb resistor integral nonlinearity 2 r-inl r wb , v a = no connect C2 0.25 +2 lsb nominal resistor tolerance 3 ?r ab C20 +20 % resistance temperature coefficient ?r ab /?t v a = v dd , wiper = no connect 45 ppm/c r wb r wb code = 0x00 75 300 ? dc characteristicspotentiometer divider mode differential nonlinearity 4 dnl C1 0.1 +1 lsb integral nonlinearity 4 inl C1 0.2 +1 lsb voltage divider temperature coefficient ?v w /?t code = 0x40 15 ppm/c full-scale error (50 k?, 100 k?) v wfse code = 0x7f C1 C1 0 lsb zero-scale error (50 k?, 100 k?) v wzse code = 0x00 0 +0.4 +1 lsb full-scale error (10 k?) v wfse code = 0x7f C2 C0.5 0 lsb zero-scale error (10 k?) v wzse code = 0x00 0 +0.5 +1 lsb resistor terminals voltage range 5 v a, w gnd v dd v capacitance 6 a c a f = 1 mhz, measured to gnd, code = 0x40 45 pf capacitance 6 w c w f = 1 mhz, measured to gnd, code = 0x40 60 pf common-mode leakage i cm v a = v dd /2 1 na digital inputs and outputs input logic high v ih v dd = 5v 2.4 v input logic low v il v dd = 5 v 0.8 v input logic high v ih v dd = 3 v 2.1 v input logic low v il v dd = 3 v 0.6 v input current i il v in = 0 v or 5 v 1 a input capacitance 6 c il 5 pf power supplies power supply range v dd range 2.7 5.5 v supply current i dd v ih = 5 v or v il = 0 v 3 8 a power dissipation 7 p diss v ih = 5 v or v il = 0 v, v dd = 5 v 40 w power supply sensitivity pssr v dd = +5 v 10%, code = midscale 0.01 0.02 %/% dynamic characteristics 6, 8 bandwidth C3 db bw r ab = 10 k?/50 k?/100 k?, code = 0x40 600/100/40 khz total harmonic distortion thd w v a =1 v rms, f = 1 khz, r ab = 10 k? 0.05 % v w settling time (10 k?/50 k?/100 k?) t s v a = 5 v 1 lsb error band 2 s resistor noise voltage density e n_wb r wb = 5 k?, r s = 0 9 nv/hz 1 typical specifications represe nt average readings at 25c and v dd = 5 v. 2 resistor position nonlinearity error r-inl is the deviation from an ideal value measured betw een the maximum re sistance and th e minimum resistance wiper positions. r-dnl measures the relative step change from ideal between successive tap positions. parts are guaranteed monotonic. 3 v a = v dd , wiper (v w ) = no connect. 4 inl and dnl are measured at v w with the rdac configured as a potentiometer divide r similar to a voltage ou tput d/a converter. v a = v dd and v b = 0 v. dnl specification limits of 1 lsb maximum ar e guaranteed monotonic operating conditions. 5 resistor terminals a and w have no limitations on polarity with respect to each other. 6 guaranteed by design and not subject to production test. 7 p diss is calculated from (i dd v dd ). cmos logic level inputs result in minimum power dissipation. 8 all dynamic characteristics use v dd = 5 v.
ad5247 timing characteristics?5 k, 10 k, 50 k, 100 k versions table 3. v dd = 5 v 10% or 3 v 10%; v a = v dd ; C40c < t a < +125c ; u n l e ss otherwise noted p a r a e t e r b o l c o n d i t i o n s m i n tp 1 ma n i t 2 c t rfac tm c arac tr t c 2, 3 peciications appl to all parts c cloc freu enc c 4 0 0 t b f bus free ti e between tp and tart t 1 1 . 3 s t d;ta old tie repeated ta r t t 2 ater this period, the irst cloc p u lse is g e n e r a t e d . 0 . 6 s t w ow period o c cloc t 3 1 . 3 s t igh period o c cloc t 4 0 . 6 5 0 s t ;t a e tup ti e or repeated tart condition t 5 0 . 6 s t d;dat data old tie t 6 0 . 9 s t ;dat data etu p tie t 7 1 0 0 n s t f fall tie o both da and c ignals t 8 3 0 0 n s t r rise tie o both da and c ignals t 9 3 0 0 n s t ;t et u p ti e or tp condition t 10 0 . 6 s 1 tpical s p eci ications repres e nt aera g e read ings at 25c and v dd = 5 v. 2 ua r a n t eed b des i gn a n d n o t sub ect t o pro d uct i on t e st . 3 e e t i i n g d i a g r a s , figu , or locations o easu r ed alues. f i g u r e 3 1 r e 3 2 f i g u r e 3 3 re. 0 page 5 o 2 0
ad5247 rev. 0 | page 6 of 20 absolute maximum ratings table 4. t a = 25c, unless otherwise noted 1 parameter value v dd to gnd C0.3 v to +7 v v a , v w to gnd v dd terminal current, axCbx, axCwx, bxCwx pulsed 2 20 ma continuous 5 ma digital inputs and output voltage to gnd 0 v to v dd + 0.3 v operating temperature range C40c to +125c maximum junction temperature (t jmax ) 150c storage temperature C65c to +150c lead temperature (soldering, 10 sec) 300c thermal resistance 3 ja : sc70-6 340c/w 1 stresses above those listed under absolute maximum ratings may cause permanent damage to the device. this is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. exposure to absolute max imum rating conditions for extended periods may affect device reliability. 2 maximum terminal current is bounde d by the maximum current handling of the switches, maximum power dissip ation of the package, and maximum applied voltage across any two of the a, b, and w terminals at a given resistance. 3 package power dissipation = (t jmax C t a )/ ja . esd caution esd (electrostatic discharge) sensitive device. electros tatic charges as high as 4000 v readily accumulate on the human body and test equipment and can discharge wi thout detection. although this product features proprietary esd protection circuitry, permanent dama ge may occur on devices subjected to high energy electrostatic discharges. therefore, proper esd precautions are recommended to avoid performance degradation or loss of functionality.
ad5247 typical perf orm ance cha r acte ristics code deimal rhe os tat mode inl ls b 0 10 0 02 10 1 2 48 4 80 112 128 08 0 04 02 04 0 08 v dd 27v v dd 55v t a 25 c r ab 10k ? f i gur e 2 . r - inl vs . co de vs . sup p l y v o l t a g e s code (decimal) re os tat mode dnl (ls b ) 0 0.5 0.4 0.3 0.2 16 32 48 64 80 96 112 128 0.1 0 0.1 0.2 0.3 0.4 0.5 v dd = 2.7v v dd = 5.5v t a = 25 c r ab = 10k ? f i gur e 3 . r - dnl vs . c o de vs . sup p l y v o lta g e s code (decimal) 0 0.25 0 0.05 0.25 16 32 48 64 80 96 112 128 0.20 0.15 0.10 0.05 0.10 0.15 0.20 v dd = 2.7v r ab = 10k ? f i gur e 4 . inl vs . code vs . t e m p e r a t ur e code (decimal) p o te ntiome te r mode dnl (ls b ) 0 0.25 0.20 0.15 0.10 16 32 48 0.05 0 0.05 0.10 0.15 0.20 0.25 64 80 96 112 128 t a = 40 c, 25c, 85 c, 125c 4 0 c 25 c 85 c 125c v dd = 2.7v r ab = 10k ? f i gur e 5 . dnl vs . c o de vs . t e m p e r a t ur e code (decimal) 0 0.25 0 0.05 0.25 16 32 48 64 80 96 112 128 0.20 0.15 0.10 0.05 0.10 0.15 0.20 v dd = 2.7v v dd = 5.5v t a = 25 c r ab = 10k ? f i gur e 6 . inl vs . code vs . sup p l y v o l t age s code (decimal) 0 0.25 0 0.05 0.25 16 32 48 64 80 96 112 128 0.20 0.15 0.10 0.05 0.10 0.15 0.20 t a = 25 c r ab = 10k ? f i gur e 7 . dnl vs . c o de vs . sup p l y v o l t a g e s rev. 0 | page 7 of 2 0
ad5247 code (decimal) rheostat mode inl (lsb) 0 1.0 0.8 0.6 0.4 16 32 48 0.2 0 0.2 0.4 0.6 0.8 1.0 64 80 96 112 128 t a = 40 c t a = +25c t a = +85c t a = +125c t a = 40c t a = +85c t a = +25 c t a = +125c 03876-0-040 f i gur e 8 . r - inl vs . co de vs . t e m p e r a t ur e code (decimal) re os tat mode dnl (ls b ) 0 0.5 0.4 0.3 0.2 16 32 48 0.1 0 0.1 0.2 0.3 0.4 0.5 64 80 96 112 128 t a = 40 c, 25c, 85 c, 125c 4 0 c 25 c 85 c 125c v dd = 2.7v r ab = 10k ? f i gur e 9 . r - dnl vs . c o de vs . t e m p e r a t ur e temperatre ( c) reostat mode inl (lsb) 40 3.0 0.5 0 25 10 5 20 35 50 65 80 2.5 2.0 1.5 1.0 fse, f ll- sc a l e er r o r ( l sb ) 95 110 125 v dd = 5.5v, v a = 5.5v v dd = 2.7v, v a = 2.7v 03876-0-042 f i gure 10. f u ll- s c al e e rror v s . t e m p er a t ur e temperatre (c) zs e , ze ro-s cale e rror (ls b ) 40 0 0.25 0.50 0.75 25 10 5 1.00 1.25 1.50 20 35 50 65 80 95 110 125 03876-0-043 v dd = 5.5v, v a = 5.5v v dd = 2.7v, v a = 2.7v f i gure 11. zero -s c a le e r r o r v s . t e mpe r a t ur e temperatre ( c ) i dd, s p p l crre nt ( f i gure 12. sup p l y current v s . t e mper at ur e code (decimal) re os tat mode tempco (ppm/ c) 0 500 400 300 200 16 32 48 64 80 96 112 128 200 300 400 500 100 0 100 03876-0-045 v dd = 2.7v r ab = 10k ? f i g u re 13. r h e o s t at m o de t e mpco ?r wb /?t v s . code rev. 0 | page 8 of 2 0
ad5247 code (decimal) potentiometer (ppm/ c) 0 1 0 5 0 5 16 32 48 25 30 15 20 10 64 80 96 112 128 03876-0-046 t a = 40c to +125c t a = 40c to +85 c v dd = 2.7v r ab = 10k ? f i gure 1 4 . p o tentiom e ter m o de t e m p co ? v wb /? t vs . c o de gain ( d b) 10k 6 1 2 1 8 2 4 3 0 3 6 0 4 2 5 4 100k 1m 10m 6 0 0x40 1k 4 8 0x20 0x10 0x08 0x04 0x02 0x01 03876-0-047 freenc () f i gure 15. g a in vs. f r equ e nc y vs. c o d e , r ab = 5 k? 10k 6 1 2 1 8 2 4 3 0 3 6 0 4 2 5 4 100k 1m 10m 6 0 0x40 1k 4 8 0x20 0x10 0x08 0x04 0x02 0x01 03876-0-048 gain ( d b) freenc () f i gure 16. g a in vs. f r equ e nc y vs. c o d e , r ab = 10 k? 10k 6 12 18 24 30 36 0 42 54 100k 1m 10m 60 0x40 1k 48 0x20 0x10 0x08 0x04 0x02 0x01 03876-0-049 gain ( d b) freenc () f i gure 17. g a in vs. f r equ e nc y vs. c o d e , r ab = 50 k? 10k 6 12 18 24 30 36 0 42 54 100k 1m 10m 60 0x40 1k 48 0x20 0x10 0x08 0x04 0x02 0x01 03876-0-050 gain ( d b) freenc () f i gure 18. g a in vs. f r equ e nc y vs. c o d e , r ab = 10 0 k? 10k 6 1 2 1 8 2 4 3 0 3 6 0 4 2 5 4 100k 1m 10m 6 0 5k ? ? ? ? f i gure 19. C3 db bandwidth @ code = 0x80 rev. 0 | page 9 of 2 0
ad5247 i dd ( ? ? ? ? ? rev. 0 | page 10 of 20
ad5247 test circuits f i gr e 25 t o f i gr e 0 e i n e t e t e s t oni tions s e in t e p r o t s p e i i a t ion t a b l es 087-0-022 v ms a b dut v v v dd 1lsb v 2 n f i gre 25 t e s t c i r it or p o tenti o meter d i i e r non lin ea rit e rror i nl, dnl 087-0-02 no connect i v ms a b dut f i gre 2 t e s t c i r it or r e s i s t or p o s i tion non l i n e a r i t e rror r eo s ta t o p er a t ion r - inl, r - dnl 087-0-024 v ms1 i v dd r nominal v ms2 v r v ms1 v ms2 i a b dut f i gr e 2 7 t e st c i r i t o r i p e r resi st a n e 087-0-025 ? ? ? ? rev. 0 | page 11 of 20
ad5247 i 2 c interface table 5 rite moe s 0 1 0 1 1 1 0 a x d d 5 d 4 d d 2 d 1 d 0 a p slae aress bte data bte table 6. r e ad mode s 0 1 0 1 1 1 0 r a 0 d 6 d 5 d 4 d 3 d 2 d 1 d 0 a p slave address byte data byte s = s t a r t c o n d i t io n. p = s t o p c o n d i t io n. a = a c k n o w le dge . x = d o n t c a r e . w = w r i t e . r = re ad . d6, d5, d4, d3, d2, d1, d0 = d a t a bi ts. t 1 t 3 t 4 t 2 t 7 t 8 t 9 ps p s t 10 t 5 t 9 t 8 scl sda t 2 t 6 03876-0-003 f i g u re 31. i 2 c inter f a c e , detai l ed t i m i ng di a g r a m scl frame 1 frame 2 start b master ac b ad5247 slave address bte stop b master data bte sda 0 1 0 1 1 1 0 r/w xd 6 d 4 d 3 d 2 d 1 d 0 1 19 ac b ad5247 1 9 d5 03876-0-004 f i g u re 32. w r it ing t o t h e r d a c r e g i s t e r no ac b master scl sda 0 1 0 1 1 1 0 r/w 0 d6 d5 d4 d3 d2 d1 d0 1 9 1 9 frame 1 frame 2 start b master ac b ad5247 slave address bte rdac register stop b master 03876-0-005 f i gure 3 3 . rea d i n g fr om the r d a c reg i st er rev. 0 page 12 of 20
ad5247 ope ration te ad5247 is a 128-p o si tion, ig i t a l l o n t r o l l e a r i ab le r e sis t o r vr e ie a n i n t e r n a l p o e r - o n p r es et plaes t e i pe r a t m i s a l e ri n g po e r - o n , i s i m p l i i e s t e e a l t o ni tion r e o e r a t p o e r - p programming the variable resi stor r h eos t at ope r ation he n o inal r e sis t a n e o t h e r e t e e n t e r inals an is a a i la l e in a n h e i na l t o o r t h r e e ig i ts o t h e p a r t n u er et e r i n e t h e n o inal r e sis t a n e al u e e g he n o inal re s i st an e r o th e vr has o n t a t p o in ts aes s e t h e i p e r t e r i n al pl us t h e ter inal o n t a t he i t a t a in t h e r l a t h is eo e t o s e le t on e o the p o s s i le se t t in g s s s u in g a p a r t is us e th e i p e r s i rs t o nne t io n s t a r ts a t t h e t e r inal o r a t a in e t h ere is a i p e r o n t a t r e sist ane suh a on n e t i o n i els a i ni u o r e sis t a n e et een ter inals an h e s e on o n n e t i o n is t h e i rst t a p p o in t h ih o r r esp o n s t o r r r o r a t a he thir onn e tio n is the n e t ta p p o in t r e p r es en tin g o r a ta a n s o on a h a ta al u e i n r e a s e o e s t h e i p e r u p t h e r e sis t o r laer un t i l t h e las t t a p p o in t is r e a h e a t r r i gur e i gur e ui a le nt r ir ui t s h o s a si p li i e i ag ra o t h e e u i a len t r ir ui t h er e t h e last r e sis t o r s t r i n g i l l n o t e aes s e r or r r r h e g e n e ral e ua ti o n e t e r in in g th e i g i tall p r ogra e o u t p u t r e s i s t a n e et een a n i s w ab wb r r d d r + = d r d a r ab r w r ab a r wb r d a r wb r dd r wb r ab r w b wr wb w b a rd a w a r wa w b r wa w ab wa r r d d r + = r ab b r wa rd a r wa r dd r wa b r ab r
ad5247 programm ing t h e po tent iomet e r divi der voltage o u tp ut ope r ation th e di g i t a l p o te n t i o me te r e a s i ly ge ne r a te s a volt age d i v i de r a t w i p e r - to - b a n d w i p e r - to - a prop or t i ona l to t h e i n put volt age a t a - t o -b . u n l i k e t h e p o la r i ty o f v dd t o gnd , whic h m u s t be p o s i t i ve, vol t ag e ac ro ss a C b , w C a , and w C b c a n b e a t e i t h e r po l a ri t y . i f ig n o r i n g t h e e f fe c t o f t h e w i p e r r e sist a n ce fo r a p p r o x im a t ion, co nne c t in g t h e a t e r m ina l t o 5 v a n d t h e b ter m ina l t o g r o u nd p r o d uces a n ou t p u t v o l t a g e a t the wi p e r - t o -b star tin g a t 0 v u p t o 1 ls b les s than 5 v . e a c h l s b o f v o l t a g e is e u a l t o th e v o l t a g e a p p l ie d acr o s s t e r m inal ab divided b y t h e 128 p o si t i o n s o f t h e p o t e n t iom e t e r divider . th e ge n e ral e u a t i o n def i nin g t h e output vo lt ag e at v w wi t h r e s p e c t t o g r o u n d f o r a n y valid in p u t v o l t a g e a p plie d t o t e r m ina l s a and b is a w v d d v 128 ) ( = = i 2 c compatible 2-wire serial bus the f i rs t b y t e o f th e ad5247 is a s l a v e addr es s b y t e (s ee a n d ) . i t has a 7- b i t sl a v e addr ess and a r/ w bit . t h e s e v e n ms bs o f t h e sla v e addr es s a r e 0101110 f o llo w e d b y 0 f o r a wr i t e co mmand o r 1 t o place t h e de vic e in r e ad m o de . t a b l e 5 a b l e 5 t a b l e 6 the 2- wir e i 2 c s e r i a l bu s proto c o l op e r a t e s a s f o l l ow s : 1. the mas t er ini t i a t e s da t a t r an sfer b y es t a b l is hing a st a r t co ndi t ion, w h ich is w h e n a h i g h -t o-lo w t r a n s i t i o n o n t h e s d a line o c c u r s while scl is hig h (s e e ). th e fol l o w in g b y t e i s t h e sla v e addr es s b y t e , w h ich co n s is ts o f t h e 7- b i t sla v e addr es s fol l o w e d b y a n r/ w bi t ( t h i s bi t de te r m i n e s w h e t he r da t a wi l l b e re ad f r om or w r i t te n to t h e sla v e de v i ce ). f i gur e 3 2 i gur e 3 2 the s l a v e w h os e addr es s co r r esp o n d s t o t h e t r an smi t t e d addr es s r e s p onds b y p u l l in g t h e s d a l i n e lo w d u r i n g t h e nin t h clo c k p u ls e (t his is t e r m e d t h e ack n o w le dg e b i t). a t th i s s t a g e , all o t h e r devi ce s o n t h e b u s r e m a in idle wh ile t h e s e l e c t e d d e v i c e wai t s for da t a to b e wr it te n to or re ad f r om i t s se ri al r e gi s t e r . i f th e r / w b i t is hig h , t h e mas t er wi l l r e ad f r o m t h e sla v e de v i ce . on t h e o t h e r hand , if t h e r/ w bit i s lo w , t h e mast er wi l l wr i t e t o t h e s l a v e de vi ce . 2. i n wr i t e m o de , a f t e r ack n o w le dg em e n t o f t h e s l a v e addr es s b y te, t h e ne x t by te i s t h e d a t a by te. d a t a i s t r ans m i tte d ove r th e s e r i al b u s in s e q u en ces o f nin e c l o c k p u ls es (eig h t da ta bi t s f o l l ow e d by a n a c k n ow l e d g e bi t ) . t h e t r a n s i t i on s o n th e s d a line m u s t o c c u r d u r i ng th e lo w p e r i o d o f scl an d r e m a in sta b le d u r i n g th e hig h p e r i o d o f scl (s e e t ) . 3. i n r e ad mo de, af ter ack n o w le dg m e n t o f t h e sl a v e addr ess b y t e , da t a is r e cei v ed o v er the s e r i al b u s in s e q u en ces o f nin e c l o c k p u ls es (a s l ig h t dif f er en c e f r o m wr i t e m o de , w h er e eig h t da t a b i ts a r e fol l o w e d b y a n ack n o w le dg e b i t). s i m i la r l y , th e tra n s i ti o n s o n t h e s d a lin e m u s t occu r d u r i n g the lo w p e r i o d o f scl and r e m a in s t ab le d u r i n g t h e hig h p e r i o d o f scl (s e e ) . f i gur e 3 3 i gur e 3 3 4. w h en al l da ta b i ts ha v e been r e ad o r wr i t t e n, a s t o p co ndi t ion is est a b l ish e d b y t h e mast er . a s t o p co n d i t ion is def i n e d as a lo w-to -hig h t r a n s i t i o n o n t h e sd a l i ne w h i l e scl is hig h . i n wr i t e mo de , t h e mas t er wi l l p u l l t h e sd a lin e hig h d u r i n g t h e t e n t h clo c k p u ls e t o es t a b l ish a st o p co ndi t ion ( s e e f ) . i n r e ad m o de, t h e m a ster w i l l is s u e a n o a c k n o w le dg e fo r t h e nin t h clo c k p u ls e (i .e ., t h e s d a li ne r e ma i n s hig h ). the mas t er wi l l t h en b r in g t h e s d a line lo w bef o r e th e t e n t h c l o c k p u ls e , which g o es hig h t o est a b l ish a s t o p co n d i t ion (s e e f ) . a r e p e a t e d wr i t e f u n c t i on g i v e s t h e us er f l exi b i l i t y t o u p da te t h e rd a c o u t p ut a n u m b er o f t i m e s a f t e r addr es si ng t h e p a r t o n ly o n ce . f o r exa m ple , a f t e r t h e r d a c has ack n o w l e dg e d i t s s l a v e addr es s i n t h e w r i t e m o de , t h e r d a c o u t p u t wi l l u p da te o n e a ch s u cces s iv e b y t e . i f dif f er en t in s t r u c t io n s a r e n e e d e d , t h e w r i t e / re a d mo d e h a s to st ar t ag ai n w i t h a n e w s l a v e a d d r e s s a n d da ta b y t e . s i m i la r l y , a r e pea t ed r e a d fu n c ti o n o f th e rd a c i s also allo w e d . rev. 0 | page 14 of 20
ad5247 a v dd w gnd 03876-0-010 level shif ting for bi directio nal interface w h i l e m o s t legac y sys t em s ma y b e o p era t e d a t on e v o l t a g e , a n e w co m p o n en t m a y b e o p ti mized a t a n o t h e r . w h e n t w o sys t em s o p era t e t h e s a me sig n al a t t w o dif f er en t v o l t a g es, p r o p e r le v e l shif t i ng is n e e d e d . f o r in st a n c e , o n e can us e a 3.3 v e 2 pro m to i n te r f ac e wi t h a 5 v di g i t a l p o te n t i o me te r . a l e v e l shif t i ng s c h e m e is n e e d e d t o ena b le a b i dir e c t iona l co mm u n i- ca ti o n so th a t th e se t t i n g o f th e d i gi t a l po t e n t i o m e t e r ca n b e sto r e d to and r e t r ie ve d f r o m t h e e 2 p r o m . f s h o w s one o f th e im p l e m en ta ti o n s . m 1 a n d m 2 ca n be a n y n c h a n n e l sig n al fet s , o r if v dd falls be lo w 2.5 v , m1 an d m2 ca n be lo w thr e s h old fet s s u c h as t h e f d v301n. i g u r e 3 5 f i gure 35. l e vel s h if ting for o p e r at ion at d i ffe r e nt p o te ntials e 2 prom ad5247 sda1 scl1 d g r p r p 3.3v 5v s m1 scl2 sda2 r p r p g s m2 v dd1 = 3.3v v dd2 = 5v d 03876-0-007 esd protection a l l dig i t a l in pu t s a r e p r o t e c te d wi t h a s e r i es in pu t r e sisto r a n d p a ral l e l z e n e r e s d s t r u c t ur es sh o w n i n a n d . this a p plies t o t h e dig i t a l in p u t p i n s sd a and s c l. f i gur e 3 6 f i g u re 36. e s d pr ot ec t i o n of d i g i t a l p i ns f i gur e 3 7 f i g u re 37. e s d pr ot ec t i o n of r e s i s t o r t e r m in als logic 340 ? gnd 03876-0-008 a,w 03876-0-009 gnd terminal voltage operating ra nge the ad5247 v dd a n d g n d p o w e r su p p ly def i n e s t h e b o u n dar y c o ndi t i o ns for prop e r 3 - te r m i n a l di g i t a l p o te n t i o me te r o p era t ion. s u p p ly sig n als p r es en t o n t e r m inals a an d w t h a t e x ceed v dd o r gnd wi l l b e clam p e d b y t h e in ter n a l fo r w a r d b i as e d dio d es (s e e ) . f i gur e 3 8 f i g u re 38. m a x i mu m t e r m i n a l v o lt ag es s e t by v dd and g n d i gur e 3 8 maximum operating current a t lo w co de values, t h e us er s h o u ld b e a w a r e t h a t d u e t o lo w r e sis t a n c e val u e s , t h e c u r r en t t h r o ug h t h e rd a c ma y exce e d th e 5 m a lim i t. i n f , a 5 v s u p p l y is p l ac ed o n t h e wi p e r , a n d t h e c u r r en t t h r o ug h ter m in a l s w an d b is plo t te d w i t h r e s p ec t t o co de . a lin e is als o dr a w n deno tin g t h e 5 m a c u r r en t limi t. n o t e tha t a t lo w co de va l u es (p a r tic u la rl y f o r th e 5 k and 10 k o p t i o n s), t h e c u r r en t le vel in cr e a s e s sig n if ica n t l y . c a r e s h o u ld b e t a k e n t o limi t t h e c u r r en t f l o w b e twe e n w and b i n this s t a t e t o a maxim u m co n t in uo us c u rr en t o f 5 m a and a max i m u m p u ls e c u r r en t o f n o m o r e t h an 20 m a . o t h e r w is e, deg r ada t ion o r p o ssi b le de st r u c t io n o f t h e in t e r n a l sw i t ch co n t ac ts can o c c u r . i gur e 3 9 f i g u re 39. m a x i mu m o p e r at ing cur r e n t code (decimal) iwb curre nt (ma) 0 0.01 0.10 1.00 10.00 16 32 48 64 80 96 112 128 100.00 03876-0-057 5ma current limit r ab = 5k ? r ab = 10k ? r ab = 100k ? r ab = 50k ? sin c e t h e es d pr o t e c t i o n di o d e s limi t t h e v o lt ag e co m p l i an ce a t t e r m ina l s a and w (s e e f ), i t is im p o r t an t t o p o w e r v dd /gn d bef o r e a p p l yin g a n y vo l t a g e t o t e r m inals a a n d w ; o t h e r w is e , t h e dio d e wi l l b e fo r w a r d b i as e d s u ch t h a t v dd wi l l b e p o w e r e d uni n t e n t io nal l y an d ma y a f fe c t t h e r e s t o f t h e us er s cir c ui t. th e ide a l p o w e r - u p s e q u en c e is in t h e fol l o w in g o r der : gnd , v dd , d i g i t a l i n p u t s , a n d t h e n v a /v w . t h e r e l a t i ve ord e r of po w e ri n g v a an d v w an d t h e di g i t a l i n p u ts is no t im p o r t a n t as l o ng a s t h e y are p o we re d af te r v dd /gnd . rev. 0 page 15 of 20
ad5247 layout and poer supply b y passing i t is a g o o d p r ac tice t o em p l o y a co m p ac t, m i nim u m lead-len gt h la yo u t desig n . th e le ads t o t h e in p u ts sh o u ld be as dir e c t as pos s i b le wi th a m i n i m u m co n d u c t o r le n g th . g r o u n d p a th s s h o u ld ha v e lo w r e sis t a n ce an d l o w ind u c t an ce . s i m i l a r l y , i t is a g o o d p r ac tic e to b y p a s s th e p o w e r s u p p lies wi t h q u al i t y ca pa c i t o r s f o r o p ti m u m s t a b il i t y . s u p p l y l e a d s t o th e de vice s h o u l d b e b y p a s s e d wi th 0.01 f t o 0.1 f dis c o r c h i p cera mic c a p a ci to rs. lo w es r 1 f t o 10 f ta n t al um o r e l ec tr o- l y tic ca p a ci t o rs s h o u ld als o be a p p l ied a t t h e s u p p lies t o mini mi ze an y t r an sien t dist ur b a n c e an d lo w f r e q uen c y r i p p le (s e e ) . n o t e tha t t h e dig i tal g r o u nd sho u ld als o be j o i n e d re motely to t h e an a l o g g r ou nd a t one p o i n t to mi ni m i ze th e gr o u n d bo un ce . f i gur e 4 0 f i g u r e 4 0 . p o w e r su pp l y by pa s s i n g ad5247 v dd c1 c3 gnd 10 f 0.1 f + v dd 03876-0-011 constant bias to retain resistance setting f o r us ers wh o desir e n o n v ol a t ili t y b u t ca nn ot j u s t if y t h e addi tio n al cos t fo r th e eemem , th e ad5247 ma y be con s ider e d a s a lo w cos t al t e rn a t i v e b y m a in ta in i n g a co n s t a n t b i a s t o r e ta in th e wi p e r s e t t ing. th e ad5247 was desig n e d s p ecif ical l y wi th lo w p o w e r in mind , which al lo ws lo w p o w e r co n s um p t io n ev en in b a t t e r y -o p e ra t e d syst em s. the g r a p h i n dem o n s tr a t es t h e p o w e r co n s u m p t ion f r o m a 3.4 v 450 mahr l i -io n ce l l ph one ba t t er y , which is co nnec t e d t o th e ad5247. the m e as ur e m e n t o v er t i me sh o w s t h a t t h e de vi ce dra w s a p p r o x ima t e l y 1.3 a an d con s u m es n e g l ig ib le p o w e r . o v er a co urs e o f 30 da ys, t h e b a t t er y w a s deplet e d b y les s t h a n 2 % , t h e ma jo r i ty o f w h i c h is d u e t o t h e in t r in sic le aka g e c u r r en t o f t h e ba t t e r y i t s e lf . f i g u r e 4 1 f i gure 4 1 . ba tter y o p er a t i n g li fe d e p l etio n days battery life depleted 0 90% 92% 94% 96% 51 0 1 5 98% 100% 102% 104% 106% 108% 110% 20 25 30 03876-0-059 t a = 25 c t h i s d e m o n s tra t e s th a t co n s ta n t l y b i a s in g t h e p o t i s n o t a n im p r ac t i c a l a p pro a ch. m o st p o r t ab le de vices do n o t r e q u ir e t h e r e m o val o f b a t t er ies fo r t h e p u r p os e o f cha r g i n g . a l t h o u g h t h e r e sis t a n c e s e t t ing o f t h e a d 524 7 wi l l b e los t w h en t h e b a t t e r y n e e d s r e p l a c em e n t , s u c h ev en t s occur ra th e r i n f r eq ue n t l y s u c h t h a t t h is i n con v enie n c e is j u st if i e d b y t h e lo w e r cost a n d sma l le r size o f f e r e d b y t h e ad5247. i f and w h en t o tal p o w e r is los t , th e u s e r shou l d b e prov i d e d w i t h a me a n s to a d ju st t h e s e tt i n g acco r d in g l y . evaluation board a n e v a l u a t i on b o ard, a l ong w i t h a l l ne c e ss ar y s o f t w a re, i s a v a i la b l e t o p r og ra m the ad52 47 f r o m a n y pc r u nnin g w i n d o w s? 98, w i n d o w s 2000?, o r w i n d o w s xp?. th e g r a p hic a l us er in t e r f ace , as s h o w n i n , is s t ra ig h t f o r w a r d a n d e a sy t o us e . m o r e det a i l e d info r m a t ion is a v a i lab l e in t h e us er m a n u al , wh i c h co m e s wi th t h e boa r d . f i gu r e 4 2 f i g u re 42. a d 5 2 4 7 ev aluat i on bo ar d s o f t w a r e 03876-0-061 rev. 0 | page 16 of 20
ad5247 pin conf iguration and fu nction descriptions 1 2 3 6 5 4 v dd gnd scl ad5247 top view (not to scale) a w sd a 03876-0-002 f i g u re 43. p i n co nf i g ur at i o n ( 6 -l ead s c 70) ta ble 9. a d 52 47 pi n f u nct i o n d e s c ri pt i o ns pin no. mnemonic description 1 v dd positive power s u pply. 2 gnd digital ground and b termination voltage. 3 scl serial clock input. positive edg e triggered. 4 sda serial data inpu t/ output. 5 w w t e r m i n a l . 6 a a t e r m i n a l . rev. 0 page 17 of 20
ad5247 outline dimensions 0. 2 2 0. 0 8 0. 46 0. 36 0. 26 8 4 0 0. 3 0 0. 1 5 1. 00 0. 90 0. 70 sea t i n g p l ane 1. 10 m a x 3 5 4 2 6 1 2. 0 0 bs c pin 1 2. 10 bs c 0. 6 5 bs c 1. 25 bs c 1. 3 0 bs c 0. 10 m a x 0.10 coplanarity compliant to jedec standards mo-203ab f i g u re 44. 6-l e ad t h in s h ri nk s m a ll o u t lin e t r ans i s t o r [ s c70] (k s-6) di me nsio ns sho w n i n mi ll im e t e r s ordering guide m o d e l r ab (k?) temperature r a nge package descri ption package option branding ad5247bs5-r2 5 C40c to +125c 6-lead sc70 s-6 d1e ad5247bs5-rl 7 5 C40c to +125c 6-lead sc70 s-6 d1e ad5247bs10-r2 10 C40c to +125c 6-lead sc70 s-6 d19 ad5247bs10-rl7 10 C40c to +125c 6-lead sc70 s-6 d19 ad5247bs50-r2 50 C40c to +125c 6-lead sc70 s-6 d18 ad5247bs50-rl7 50 C40c to +125c 6-lead sc70 s-6 d18 ad5247bs100-r2 100 C40c to +125c 6-lead sc70 s-6 d17 ad5247bs100-rl7 100 C40c to +125c 6-lead sc70 s-6 d17 ad5247eval see note 1 evaluation boar d 1 th e eval uat i on board is s h ippe d with the 10 k r ab re si st or opt i on ; h o w e ver, t h e boa r d i s com p a t i b le wi t h a ll a v a i l a b le r e si st or va lu e opt i on s. rev. 0 page 18 of 20
ad5247 notes rev. 0 | page 19 of 20
ad5247 notes pr as e o lien s e i 2 c o m p on e n ts o analog de ies o r on e o i t s s b l ien s e a s s o i a t e c o m p a n ies on e s a lien s e o r t e p r a ser n er t e p ili p s i 2 c p a t e n t r i g ts to s e t es e om p o n e n ts in an i 2 c ss t em, p r o i e t a t t e sst em o no r m s to t e i 2 c s t a n a r s p e i ia t ion as e i ne b pi l i p s 200 analo g de ies, in all rigts resere tra em arks an registere tra ema r ks are te prop ert o teir respetie oners c0870 00 rev. 0 | page 20 of 20

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