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ob3328/OB3328N high performance ccfl controller full bridge ? o n - b r i g h t e l e c t r o n i c s con f idential ob_do c _ d s_2800 - 1 - general description the ob332 8 is a unique, h i gh-effici en cy and high - pre c isi on col d catho de fl uore s cent la mp (ccf l) backlig ht co ntrolle r ic d edicated to full bridg e config uratio n. the controll er i s de sign e d to drive singl e or multiple ccf ls in liquid cryst al display (lcd) appli c a t ions. the ob332 8 convert s unre gulate d dc input voltage to the pure sin usoi dal voltage and cu rre nt waveforms i n requi red freque ncy, to ignite and operate ccf l lamps. the ob332 8 provides a high deg ree of design flexibility by offering great program m abil ity for key para m eters whi c h incl ud e operating freque ncy, stri king frequ ency, st riki n g time, bu rst dimming freque ncy, so ft-start time, and soft on/o ff time for burst dimmin g . the ob332 8 offers variab le dimming mode s and sele ctabl e di mming pol ari t y 1 . both internal burs t and externa l low frequ ency pwm (lpwm) dimming met hod s are avai lable for a wid e range of dimming con t rol (10% to 100%). fu rthermo re, analo g dimmi ng is provide d thro ugh external dc input control to achi eve 40% to 100 % dimmin g rang e. the highly integrated ob3 328 provid es complet e prote c tion fe ature s covering ic un de r voltage lockout (uvl o), output o v er voltage prote c tion, and lamp fail safe fun c tion. the ob33 28 is available i n dip-16, s op-16 a nd tssop-16 p a ckag es. featur es z suppo rt wide input voltage z full brid ge to pology z high p r e c isi o n referen c e a nd frequ en cy control z built-in pea k detect ci rcuit redu ce s bom count z suppo rt singl e or multi-la m p appli c ation s z high flexibility of dimming configuration: analog di mm ing internal/external burst (p wm) mode di m m ing con c u r rent b u rst an d anal og dimmin g control z flexible user prog ram mabil ity: operating fre quen cy striking fre q u ency, stri king voltage and ti me soft s t art and s o ft on/off ti me internal bu rst mode fre que ncy z comp re hen si ve protectio n coverage: ic sup p ly und er voltage lo ckout (uvlo ) output over v o ltage protect i on (ovp) lamp fail saf e function applications z noteb oo k co mputer z lcd monito r z lcd tv z lcd flat pane l display fo r instrum ent, aut omobil e and ha ndh old device 1 the ob33 28 is w i th positive dimming polarit y w h il e it s counter p a rt ob3 328n is in negative dimming polarity . typical application c i rcuit vin +5v ena adim ccfl gn d cs 1 cm p / s s t 2 st i m e 3 vs 4 ri 5 gn d 6 ga t e - p 2 7 ga t e - n 2 8 ga t e - p1 9 ga t e - n1 10 vdda 11 bf/dmod 12 adim 13 dd im 14 ena 15 rt 16 o b 33 28 dd im figure1: ob3328 typical application schematic on-bright confidential to bonafide http://
ob3328/OB3328N high performance ccfl controller full bridge ? o n - b r i g h t e l e c t r o n i c s con f idential ob_do c _ d s_2800 - 2 - absolute maximum ratings parameter value vdda input v o lt age to g n d 7v i/o to gnd -0.3 to vdda + 0.3v operating am bient t e mperature t a -20 to 85 o c operating ju nction t e mperature t j 150 o c min/max s t orage t e mpe r at ure t stg -55 to 150 o c lead temperature (10 sec) 260 o c not e : s t resse s be y ond those listed unde r ?absolu t e maximum ratings? ma y ca use perman ent damage to the device. these are stress rating s onl y , fu nctional operation of th e device at these or an y ot her conditions be y ond those ind i cated under ?recommende d operating conditions? is not implied. exposur e to absolute maximum-rated con d itions for exten ded periods may af fect device r e liability . recommended operating range parameter value vdda volt ag e 4.5v to 5.5v operating frequency 30 to 150khz package thermal characteristics parameter value thermal resistance ja (sop) 85 o c /w thermal resistance ja (dip) 60 o c /w ordering information 2 part number description ob3328rp dip16, pb-free ob3328qp sop16, pb-free ob3328tp tssop16, pb-free OB3328Nrp dip16, pb-free OB3328Nqp sop16, pb-free OB3328Ntp tssop16, pb-free 2 ob332 8n is ne gative dimmi ng version of ob33 2 8. ordering information ob3328(n) x x x package package pb free packing q: sop 1 6 r:d i p16 t:tssop16 blank:no r ma l p:le ad-free bla n k:tube a: taping high performanc e ccfl controller on-bright confidential to bonafide
ob3328/OB3328N high performance ccfl controller full bridge ? o n - b r i g h t e l e c t r o n i c s con f idential ob_do c _ d s_2800 - 3 - packag e m a rking information sop16 y: ye ar code (0-9) w w : w eek code (1-52) q:so p16 p:le ad-fre e s: internal co de lt yww ob3328qp s dip16 y: year code (0-9) w w : we ek code (1-52) r:dip16 p:l e ad-fr e e s: internal code lt yww ob3328rp s tsso p16 y: year code (0-9) ww: w eek c ode (1 -52) t:tssop16 p:lea d -free s: inte rna l co de lt yww ob3328tp s on-bright confidential to bonafide
ob3328/OB3328N high performance ccfl controller full bridge ? o n - b r i g h t e l e c t r o n i c s con f idential ob_do c _ d s_2800 - 4 - pin configuration terminal assignment pin number pin name i/o pin function 1 cs input lamp current sense input 2 cmp/sst i/o con n e c ted to loop com pen sation ca pacito r , this cap a cito r als o s e ts the s o ft s t art time 3 stime i/o connect to a capacitor to set striking time 4 vs input output voltage sense input 5 ri i/o connected to resist or setting strike frequency 6 gnd grou nd ground 7 gate-p2 o utput p-mosfet gate drive output2 8 gate-n2 o utput n-mosfet gate drive output2 9 gate-p1 o utput p-mosfet gate drive output1 10 gate-n1 o utput n-mosfet gate drive output1 11 vdda powe r +5v power supply 12 bf/dmod i/o con ne c ted to capa citor set s burst frequ ency or con n ected to gnd sel ect s external lp wm mode dim m ing 13 adim input dc signal input for analog mode dimming 14 ddim input digital mode dimming control signal input 15 ena input chip enable control input, active high 16 rt i/o connected to an external resistor sets operating frequency cs 1 stime 3 vs 4 ri 5 gnd 6 ga te-p2 7 16 r t 15 ena 14 ddim 13 adim 12 bf/dmo d 1 1 vdda 10 ga te-n1 ga te-n2 8 9 ga te-p1 cmp/sst 2 on-bright confidential to bonafide
ob3328/OB3328N high performance ccfl controller full bridge ? o n - b r i g h t e l e c t r o n i c s con f idential ob_do c _ d s_2800 - 5 - functional block diagram 2 3 14 7 6 1 5 4 15 9 10 11 12 13 cs rt cmp /sst stim e ri gn d gate- n2 gat e-p1 vdd a bf/d mod vs ddim ena bandgap/ reference v_ref i_ref gate driver + - + - v_ref_dim cs_th vdd uvlo 8 adim 16 3.0ua + - v_th g ate-p2 gate-n1 pg analog & burst dimming por soft switching & output control hf osc pwm generator clk input logic pea k detect striking control ri ri gnd peak detect ea v_ref_dim lam p fail safe functions figure2: ob3 328 fun c tion al block diag ram on-bright confidential to bonafide
ob3328/OB3328N high performance ccfl controller full bridge ? o n - b r i g h t e l e c t r o n i c s con f idential ob_do c _ d s_2800 - 6 - electrical characteristics vdda =5v, ena=5v, rt=36kohm, ri =107koh m, adim=ddim = 5 v , c bf =10nf, c st im e = 1uf, t a =25 o c if not otherwise noted. parameter sy mbol conditio n min t y p max units current consumption ic s t andby i st a ndb y ena=0v - 5 20 ua normal op era t ing i vdd - 4 ma vdda uvlo uvlo on 3.6 v uvlo off 4.4 v high frequency oscillator operating fre quen cy f op 48 50 52 khz striking fre q u ency f st k 62 65 68 khz temp. stabilit y ta = -20 o c to 85 o c - 200 - ppm/ o c min. (overla p ) duty cycle 1% max. (overlap ) duty cycle 45% low frequency oscillator for burst mode dimming burst fre quen cy 180 200 220 hz temp. stabilit y - 400 - ppm/ o c ob3328 ddim = 0v - 10 - min. burst duty ob3328 n ddim = 0v 100 % ob3328 ddim > 3v - 100 - max. burst du ty ob3328 n ddim > 3.25 10 % analog dimming control min. cs reference voltage v_ ref _ dim adim= 0 v - 0.5 - v max. cs refe ren c e voltag e v_ ref _ dim adim> 3 v - 1.25 - v external lpwm dimming control external lpwm duty 10 - 100 % high 2.0 v external lpwm logic in put level low 0.8 v error amplifier referen c e vo ltage v ref _ pk 1.2 1.25 1.3 v on-bright confidential to bonafide
ob3328/OB3328N high performance ccfl controller full bridge ? o n - b r i g h t e l e c t r o n i c s con f idential ob_do c _ d s_2800 - 7 - parameter sy mbol conditio n min t y p max units open lo op vo ltage gain 70 - db unity gain ba ndwi dth cmp=39nf 250 hz supply current soft s t art c u rrent i sst 3.0 ua soft on/off c u rrent i soft 120 ua striking time r cur r e n t i st im e - 3.0 - ua control and protection threshold on 0.8 enable threshold off 2.0 v vs regulate voltage vs pk whe n stri king 3.0 v over voltage prote c tion vs pk normal op erating 3.0 v lamp fail saf e prote c tion v cs _ pk 200 mv lamp fail saf e deglitch time 20 ms striking time r threshold v st im e 3.0 v s t riking comp letion thre sho l d v cs_pk 300 mv gate driver output ga te-n1/ g a te-n2 r on i out =70ma 8 ohm ga te-p1/ ga te-p2 r on i out =70ma 8 ohm gate driver dead time ga te-n1/ga te-p1 cmp=2v 400 ns ga te-n2/ga te-p2 cmp=2v 400 ns on-bright confidential to bonafide
ob3328/OB3328N high performance ccfl controller full bridge ? o n - b r i g h t e l e c t r o n i c s con f idential ob_do c _ d s_2800 - 8 - function description high efficiency operation the ob332 8 ccf l cont rol l er is desi gne d to drive the inverter system in full bridge top o logy, the resona nt mo de full b r id ge switche s conve r ts unre gulate d dc voltage to pure sinusoidal waveforms fo r ccfl op era t ing with high efficien cy and lo w emi emission. t h e re son ant freque ncy of the tank i s set by th e tran sform er lea k a ge indu ctan ce, prima r y seri es cap acitor and se con dary pa rallel capa cito r. the ob332 8 provide s a hi gh perfo rman ce sol ution with a low system co st. one referen c e desi gn s for singl e lamp appli c ation is shown in figure 3 o n page 9. enable the controller ob3328 is a c tivated by a pplying lo gic high to the ena input. control i s ttl logic comp a t ible. the controlle r is e nable d wh en the voltage at ena pin is highe r than 1.1v. toggling the ena sign al resets the state machi ne hen ce restart s the inv e rter sy ste m . lamp ignition and strikin g voltage re gulation a much hig her voltag e than that in normal operation is required to i gnite ccfl, especi a lly for aged la mp o r in low ambi ance tempe r ature. the prog ram m abl e stri king freque ncy, vol t age an d ignition time set by rt, ri, vs, and stime pins ensure suffici ent voltage a nd time fo r a n y ccfl ignition. ri in parallel ed wi th rt pin is u s ed to set the oscill ator freque ncy wh ich is clo s e to reson ant freque ncy of the tank at ignition stage thus provid e sufficie n t stri king voltage. the output voltage is divided by the cap a citive voltage divider (forme d by c12 a nd c13 sho w n in fi gure 3 on pa ge 9). t he divided sig na l is fed into vs pin and its pea k is comp ared wi th internal 3.0v threshol d voltage. con s e quently , the output voltage is regu lated and limited. the stri king voltage can be ap proximate d as: 12 ? 2 13 ? 0 . 3 c c v v striking once the out put voltage reache s the target level, and if cs pin voltage is le ss tha n 350 mv, the ic will initiate the stri king tim e r. an internal constant 3. 0ua cu rr ent sou r c e st a r t s t o cha r ge t h e cap a cit o r con n e c ted to stime pin. voltage hig her than 3.0v at stime pin indicate s an ignition timeout. under su ch cir c u m st an ce, p w m gat e out put s are dis a bled and thus power s w it c h es are turned off. no en ergy is further d e livered to the ccfl load. voltage at cs pin greater than 300mv indicates the lamp bein g ignited and cap a cito r at stime pin will be discha rged. capa cit or in app rop r i ate value is req u ire d to provide sufficient time (typically, 1 se con d ) to ignite the lamp. ignition time is approximated as: c[uf] = t(sec) ov er voltage protec tion duri ng n orm al ope rating, if vs peak voltag e rea c he s the internal threshold of 3.0v, the controlle r im mediately sh uts do wn th e inverte r . ovp is a latch shutd own a nd co uld only be re set by toggling ena pin. soft sta r t an d soft on/o ff external ca p acitor co nne cted to cm p/sst pin provide s soft start and sof t on/off control. at start up, an intern al cu rre nt so urce sta r ts to cha r ge the cap a cito r. co nse que ntly, voltage at cm p/sst pin increa se s gra dually and so as to the overlap tim e of the pwm gate si gnal s. this soft st art control help s to redu ce the mos fet inru sh current an d voltage stre sse s , thus expand the lam p life. the slop e of the soft st art t v ? / ? can be approximated as: rt[kohm] c 36 10 3 = t v -6 once lamp s are ignite d, the ca pa citor con ne c ted to cmp/sst pin perfo rms the loop com pen sation function. in intern al bu rst m ode di mming o r external b u rst (pwm) mo de dimmi ng con d ition s , the voltage rampi ng up and do wn a t this pin perfo rms a so ft on/off control function in each burst cy cle. normal ope r ation and str i king freque nc y the ope ratio n freque ncy is determi n ed by the external resi stor con ne c ted to rt pin. th e operation fre quen cy is cal c ulate d by th e followi ng equatio n: rt(kohm) 1800 = (khz) f op at ignition st age, ri pi n is internally co nne cted to rt pin, there f ore external resi sto r at ri pin is in parall el with the external resi sto r at rt pin. the stri king fre q uen cy can be cal c ul ate d by the on-bright confidential to bonafide
ob3328/OB3328N high performance ccfl controller full bridge ? o n - b r i g h t e l e c t r o n i c s con f idential ob_do c _ d s_2800 - 9 - following equation: ) ( // 1751 (khz) f striking kohm rt ri = lamp curr e nt re gulatio n the lamp cu rre nt is regul ated by a la mp curren t feedba ck loo p with an i nternal t r ansconductance error amplifie r, the ac la m p cu rrent is sensed by a sen s e re sist or (r1 3 in figure 3 on page 9) con ne c ted in se rie s with t he lo w voltag e termin al of ccfl la m p . the ac voltage a c ro ss the sen s e resi sto r is fed into the cs p i n. the peak voltage of sen s e d ac voltage is d ete cted an d com pare d with a 1.25v internal refe ren c e voltage. the error is amplified th at cont rol s the on time of th e full brid ge swit che s , as a result, the lamp cu rrent is reg ulated. the lamp cu rrent can be ca lc ulate d by the following equatio n: sense lamp r v i ? = 2 25 . 1 lamp fail safe fun ction s duri ng n orm a l operation, if the lamp is re moved or damag ed, the voltage at c s pin will drops to 0v. if the pea k volt age at cs pi n ca nnot b e regulate d to the predet ermined value for more than 20ms, the inverter i s l a tche d shut down. toggl ing ena resta r ts the o peratio n. dimming co ntrol thre e com m only used di mming mod e s : analo g mode dim m in g, internal b u r st mod e dim m ing an d external b u rst (pwm ) d i mming fun c tions a r e sup porte d wit hout any addi tional com po nents. the con c u r rent a nalog and b u rst a c hi eves very wid e dimming rang e. dc volta ge rangin g from 0v to 3v at adim pin perfo rms a n alog mod e dimming co ntrol. the voltage at adim pin modulate s i n ternal error amplifier refe ren c e voltag e from 0.5v to 1.25v, witch corre s po nd s to a lamp current o f approximatel y 40% to 100%. the bf/dm od pin is u s ed for internal/external burst mod e selectio n an d i nternal bu rst freque ncy setting. external bu rst (p wm) dimmin g mod e is sele cted by shorting bf/dmod pin to groun d. the ob3328 accepts a n external low f r eq u ency pwm (lpwm) sig nal to ddim pin with a voltage swi ngin g fro m less th an 0.8v to that of greate r than 2.0v. the lamp bri ght ness is cont ro lled by the duty cycle of the lpwm sign al. t he bu rst freque ncy is equal to lpwm freque ncy. internal bu rst mode dimming is obt ained by c o nnec ting a c a p a c itor to bf/dmod pin. a low freque ncy tria ngula r wavef orm gen erato r is formed by the ca p a citor alon g wit h intern al co mp a r ato r , internal cu rrent sou r ce and current sink. th e triangul ar volt age wavefo rm with p e a k of 3v and valley of 1v at this pi n is use d for th e i n ternal lo w freque ncy burst pwm gene ration. it s duty cycle so as to lamp cu rre nt is cont rolled by the dc volt a ge at ddim pin. the burst freque ncy f burst is set by the followin g equatio n: ) nf ( c 2000 = ) hz ( f bf burst a dc voltage rangin g from 0v to 3v at dim pin corre s p ond s to a lamp c u rrent of approximately 10% to 100% . pin\mode analog internal burst external lpwm bf/dmod - capacitor <0.5v ddim - 0-3v exter nal lpw m adim 0-3v - - the co ncurre nt burst a nd a nalog dim m in g control can achieves approximately 4% to 100% dimming ratio. on-bright confidential to bonafide
ob3328/OB3328N high performance ccfl controller full bridge ? o n - b r i g h t e l e c t r o n i c s con f idential ob_do c _ d s_2800 - 10 - reference application ci rcuit for single lamp figure3: ob3 328 refere nce applicatio n schem atic cs 1 cmp / s s t 2 st i m e 3 vs 4 ri 5 gn d 6 ga t e - p 2 7 ga t e - n 2 8 ga t e - p 1 9 ga t e - n 1 10 vd d a 11 bf / d m o d 12 ad i m 13 dd i m 14 en a 15 rt 16 u1 o b 3328 c3 1uf c5 10nf f1 1a r6 30k c9 47nf c1 1 2.2uf l h cn 2 c4 10nf c2 39nf r1 1 10k r1 0 10k r7 10k r13 150 c1 22uf t1 28: 22 00 zd1 5.6v c1 2 15pf 3kv c1 3 15nf c10 47nf r8 10k zd2 5.6v g1 1 s2 2 g2 3 d2 4 s1 5 d1 6 u2 ao 660 1 g1 1 s2 2 g2 3 d2 4 s1 5 d1 6 u3 ao 660 1 c7 10nf c6 10nf r3 10k r2 10k r4 10k r5 91k vi n 1 gn d 2 adi m 3 dd i m 4 en a 5 cn 1 q1 2n3904 zd1 5.6v r2 10 r1 4.7k c2 1.0uf r1 4 1k vin: 8~22v adim: 3v , max. brightne ss; 0v , min. brightness (fo r an alog mod e di mming) ddim: 3v , m a x. brightn e ss; 0v , min. brightne ss (fo r b u rst mo de di mming) ena: disable, 0-0.8v ; enable, 2-5v load: 82.5k ohm du mm y load on-bright confidential to bonafide
ob3328/OB3328N high performance ccfl controller full bridge ? o n - b r i g h t e l e c t r o n i c s con f idential ob_do c _ d s_2800 - 1 1 - packag e m e chanical data: dip 16 dimensions in millimeters dimensions in inches symbol min max min max a 3.710 4.310 0.146 0.170 a1 0.510 0.020 a2 3.200 3.600 0.126 0.142 b 0.380 0.570 0.015 0.022 b1 1.524 (bsc) 0.060 (bsc) c 0.204 0.360 0.008 0.014 d 18.800 19.200 0.740 0.756 e 6.200 6.600 0.244 0.260 e1 7.320 7.920 0.288 0.312 e 2.540 (bsc) 0.100 (bsc) l 3.000 3.600 0.118 0.142 e2 8.400 9.000 0.331 0.354 on-bright confidential to bonafide
ob3328/OB3328N high performance ccfl controller full bridge ? o n - b r i g h t e l e c t r o n i c s con f idential ob_do c _ d s_2800 - 12 - packag e m e chanical data: sop16 dimensions in millimeters dimensions in inches symbol min max min max a 1.350 1.750 0.053 0.069 a1 0.100 0.250 0.004 0.010 a2 1.350 1.550 0.053 0.061 b 0.330 0.510 0.013 0.020 c 0.190 0.250 0.007 0.010 d 9.800 10.000 0.386 0.394 e 3.800 4.000 0.150 0.157 e1 5.800 6.300 0.228 0.248 e 1.270 (typ ) 0.050 (typ) l 0.400 1.270 0.016 0.050 ? 0 o 8 o 0 o 8 o on-bright confidential to bonafide
ob3328/OB3328N high performance ccfl controller full bridge ? o n - b r i g h t e l e c t r o n i c s con f idential ob_do c _ d s_2800 - 13 - packag e m e chanical data: ts sop16 the requ est of te chnolog y : z forme d lead tip planarity to datum plan e b is + 0.025 max; z package surf ace s shall b e ro und su rface as ra 0 . 800~1.200. det ail ?d? ro und su rface sho uld b e polished finish, rough ne ss as ra 0.025 ~0.050 with d e p th 0.035 ma x; z general tolerance shall be + 0.050; z all unit s are in millimeter; on-bright confidential to bonafide
ob3328/OB3328N high performance ccfl controller full bridge ? o n - b r i g h t e l e c t r o n i c s con f idential ob_do c _ d s_2800 - 14 - important notice right to mak e chang es on-b right el ectro nic s co rp. re se rv es the right t o make correction s , mod i fication s, en han ceme nt s, improvem ent s, and other chang es to it s prod uct s and se rvi c e s at any time and to discontinue any product or servi c e without noti c e. cu stome r s should obt ai n the latest rel evant inform ation befo r e placi ng o r de rs and shoul d verify that such informatio n is cu rrent and complete. w arr anty inform ation on-b right ele c troni cs corp . warrant s pe rforman c e of it s ha rd ware produ ct s to t he spe c ification s applicable at the time of sale in acco rdan ce with it s st a nda rd warranty . t e sting and othe r quality contro l techniqu es are u s e d to the extent it deems ne ce ssary to s uppo rt this warra n ty . except whe r e mandate d by govern ment requireme nt s, testing of all p a ramete rs o f each p r odu ct is not nece s sarily pe rform ed. on-b right electroni cs corp. assumes no liability for applications assist ance or customer product design. cu stome r s are re spo nsi ble for their prod uct s an d ap pl ication s u s in g on-b right? s comp one nt s, dat a she et and ap plication note s . t o minimize th e risks asso ciated with cu stome r produ ct s a nd appli c ation s , cu stome r s sh ould provide adeq uate de sign and o pera t ing safeg uards. life supp ort on-b right electroni cs co rp .? s produ ct s are not desig n ed to be used as compo ne nt s in device s intended to support or sust ain human li fe. on-bright electronics corp. will not be held liable for any damages or cl aim s resulting from the use of it s produ ct s in medical appli c ation s . milit ar y on-b right el ectro nics co rp.? s pro du c t s a r e n ot d esig ned fo r use i n milit a r y appli c atio ns. o n-bri gh t electronics corp. will not be held liabl e for any dam ages or claim s resulting from t he use of it s product s i n milit ary appli c ations. on-bright confidential to bonafide

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