is su e 1 - n o ve mb er 20 08 1 www . z e t e x . co m ? diodes incorporated 2008 www.diodes.com a product line of diodes incorporated DN94 high performance rectifiers significantly improve server power supply efficiency dr yong ang, diode s in cor pora t ed introduction alter n at iv e appr oache s ca n impro ve the e x ist i ng me tho d s of using scho tt ky diod es in h i g h re liab ility , h i g h ava ila b ility and low downt ime se rve r sta ndby p o we r su pplie s. t w o dif f er ent second ary circuit app r oache s , including syn c h r onou s rectif icat ion a nd su per ba rrier rectifie r (sb r ?) were used to find the highest practica l efficiency in a +5vsb power supply capable of de li ve ri ng 27w p eak p o we r . ef f i ci ency impr ove m e n ts were mea s ured i n a n exp eri m ent a l conv ert e r , a t 3 . 5 % f o r syn c h r onou s r e ctificat io n an d 0.5% fo r sbr o ver the scho tt ky so lu tion. this de sign no te discusse s t h e det a ils. ser ver standby power supplies desktop de rived serv ers are de signe d to ope rat e in high re lia bili ty a n d av a ila bili ty a p pl ica t i o n en vironme n ts whe r e it must b e working cont inuously wit h ext re me ly low unsch edule d do wnt i me. t y pically t h e archite c ture of t h e powe r supply fo llows a t w o st age conve rsio n approa ch a s show n in f i g ure 1. the f r on t en d st age is a continu ous co nduct i on mod e active po wer f a cto r co rrect in g boost conv ert e r a nd de li ve ring a const a nt 400 v dc ra il t o a dow nstre a m f o rwa r d dc- d c co nve r te r p r ocessing t h e tight ly re gulat ed +/- 1 2 v , +5v a nd +3 .3 v ra ils re quired by the system . figur e 1 - server po wer supply ar chite c t u re diag ram a se cond f l y b ack dc- d c con ver te r is re quired to ge ner a t e a isolate d 5v ou tpu t wit h 5 % t ol e ran c e . thi s v ol t ag e sou r ce i s a c t i ve whe nev er the i npu t ac vol t a ge source i s appl i e d an d re ma in s o pera t iona l e ven if the ma in o utp ut ra ils fr om t he isolat ed dc-dc co nve r te r are disa ble d. aux +5vsb, 5a c4 c5 l1 c2 c1 d1 d2 r3 r2 r1 c3 r5 vc c h v gn d f b d +5 v s b r6 r7 r4 cy 1 t1 u3 0. 1 f 5. 1k 10 k ztl 4 3 1 4. 7 k 470 f 470 f 1n f 1k v 22 f 100 k s1 m u1 u2 1n f 200 c6 c7 d3 us 1 j sm a a1 a2 b 2 b1 e m i f ilt e r an d re c t if ie r ac t i v e pow e r facto r co r r ecti o n i s o l ated dc- d c co n ver ter +12 v , +5 v , +3 . 3 v , -12 v 4- ch an n el seco n d ar y m oni t or i ng i c +400 v zsr1200 voltage regu l a t o r cb u l k o pt i on # 1 : s y nc hr onous r e c t if ie r o pt i on #2 : s u p e r b a rri e r r e c t if ie r +12 vc c_p, 100m a ac input sot2 2 3 47 f 1 f u4 2. 4 h auxili ar y p o wer su p p l y gn d rt n rtn http://
DN94 www .z ete x . c o m 2 i s s u e 1 - n o ve mb e r 20 0 8 www.diodes.com ? diodes incorporated 2008 in t h e ?st a nd by? or ?off ? mode, it de live rs pow er to the ex te rna l ci rcui ts t h a t p e rf orm sof t p o we r cont rol , w a ke o n l a n (wol ), w a ke on mod e m ( w om) or su sp end st at e a cti vi ti es. i f an ext ern a l usb de vice st imulat es the ser ver t o tra n sit fr o m sta ndby t o act i ve mode , th e powe r su pply co uld be requ ired t o pro v i d e 5 a curr ent fo r a f e w second s, t h ere f o r e t h e po wer sup p l y must be de sign ed to t h at pea k pow er . a high leve l o f inte gra t ion is d e sir a ble f o r t h e st a ndby circuit wh ich is ma de f easible by u s ing a pwm re gulat or t h a t incor pora t es a 6 5 0 v mosfe t . th e p w m r e gulat or also pr ovide s ove r curr ent pr ote c t i on to en su re the +5 vsb supply will not b e damag e d unde r out put f a ult cond it io ns. the conv ert e r is nor ma lly designed fo r critical condu ct ion mode to red u ce mosfe t t u rn o n switching loss . furthermore, the flybac k transf o r mer size can be redu ce d owing to t h e lowe r av era g e ene r gy st ora g e w h ilst it s smaller ma gne ti zing induct a nce also yiel ds a b e t t e r tr ansient li ne /l oa d re spons e . at li ght l o a d s t h e ic wi ll ope r at e in s kip cyc l e mode , re duc i ng it s s w itc h i n g losse s a nd ensuring high e f f i ciency t h rou ghout the loa d rang e. th e seconda ry w i n d ings of the tr ansfo r mer a r e re ctified and filt er ed t o pr oduce t w o o u tp uts, wh ere t h e +5 vst b main out put cha nne l is clos ed loop regu la te d thr ough a n opt ocoupler u2. the low po wer +12 v cc_s is used t o supply t h e supe rv isory ic mo nitor i ng the 12v , +5v and +3 .3 v r a ils. the superv isory ic w ill norma lly shut dow n the ac tiv e pf c st age a nd the m a in downst r ea m f o rwa r d co nve r te r if t hose ou tpu t s a r e no t se nsed at the i r no mi na l va lu e. i n t h e desi gn ex ampl e, a th ird bias o u tpu t +14vcc_p is capab l e of s upplying 100ma to the p f c controller and forwar d conv ert e r pwm re gulat or ics during no rmal o p era t ion. cri t i cal l y , much of t h e fl yba ck con ver ter i n ef fi cie n cy i s caused by the schot tky dio d es no rmal ly used fo r second ary side re ct if ica t ion on t h e +5 vsb out put . re placing t h e old ex ist i n g diode t e chnolog ie s with a more ef ficie n t re ct ifier is rec ogn ize d as a cle a r mean s of dr astically improv in g power supply ef ficie n cy . t w o diff ere n t second ary sid e rectif ie r a ppro a ches in figu re 1 were considere d in cluding syn c h r onou s mosfe t rectif ie r and t h e supe r ba rrier rect if ier . high per formance rectifier #1. synchr onous rectification with zxgd3101 th e zxgd31 01 ca n emulat e t h e perf orman c e of an idea l rectif ie r by driving a sy nchron ous mosf et e f f e ctive l y . figur e 2 sh ows a ty pica l circui t con f igura t ion fo r low side rectif icat ion. the controller can dr aw its power di rectly from the regulated +12 vcc_s output via emitter - follower t r ansistor q1 . in ot her cases wh ere a reg u la te d v o lta g e abov e 8 v is una vailable , the re co mmen dat i on is t o prov ide a ded i cat e d sup p ly thr ough a u xilia r y t r ansf ormer wind in g. r ref an d r bias are ch os en to b e 3 k ? and 1. 8k ? w h ic h se t s th e co n t ro ll er tu rn -o ff th res h o l d v a l u e to - 20 mv . f i g u re 2 - sy nchrono us re ctif ier contro l cir c u i t r bias r ref q1 r9 r8 c9 zd 1 q3 10 k 1 f u5 z x g d 3101 fm m t 4 9 1 ref bias ga t e l ga t e h g n d dra i n v c c a1 b1 +12v c c _ s , 5 0 m a o pt i on # 1 : s y nc h r o nous r ec t i f i er c8 100 1nf
DN94 is su e 1 - n o ve mb er 20 08 3 www . z e t e x . co m ? diodes incorporated 2008 www.diodes.com th e mosfe t curre nt i s sensed by t he hig h vo lt age ampl i f i e r u s i ng it s on- st at e re si sta nce a s a shunt resistor w h ich p roduces a n e ga tive dra i n v o lta g e re la tive to g r ound . th e gat e ou tpu t f r om t h e cont roller t h en v a ries accord ing l y depe nding o n the le ve l of th is sensed v o lta g e. this ca uses t he g a t e vo lt age to red uce as t he dra i n cur r ent f a l l s, ensur i ng a ra pi d t urn- off t r ansi ti on w hen the sto r ed ene r gy i n t he tra nsfor me r i s f ul l y re le ased to th e ou tpu t . f i g ure 3 sho w s th e z x g d 3 1 0 1 ? s ga te vol t age whe n fq p65 n 06 - 1 6m ? , 60 v is u s e d as t he syn c h r onou s mosf et . t he gate vo lt age re aches 10 .3 v wh en th e mo sfet curr ent w a s h i g h t o achi ev e lo w resi st ance. figur e 3 - voltage s of the synchr onous mosfet a t full loa d th eore tically , r e ducing th e resist an ce o f the mosf et will f u rt her increa se t h e e f f i ciency of the po wer supp ly at h eav y l o ad . howe ver , thi s is not ent i rel y t r ue b e cause a ver y lo w resi stan ce mosf et y i e l ds a sma l l volta g e drop a c ro ss the drain and t h e su bseque nt sensed vo lt age is un able t o in duce th e zxgd31 01 t o pro duce a hi gh e noug h gat e vo lt ag e. t h ere f o r e, the full capa bilit y of t h e mosfet is no t u t ilize d du e t o in ad equa te en hanceme nt. f i g ure 4 i l l ust r at es t hat th e p e ak g a t e vo lt a g e o n t h e 3. 3m ? , 7 5 v mo sfe t i r fb 30 77 p b f is le ss th a n 5v a n d th e g a t e vo lt ag e r i n g in g a t mosfet t u rn- on tr ansition in cu rs ad dit i onal gat e ch arge loss a nd f u rt he r de te rio r at es th e ef fi cie ncy . i f th e vo lt age across the mo sfet d r ops bel ow t he t urn -of f t hre sh ol d lev e l, t h e de vice will switch bet w e e n its of f sta t e, in which ca se the body diode is con ducting, an d its on st at e, in wh ich ca se the v o ltag e drop is t h e curre nt multiplie d by th e on resist an ce of the mosf et . al l th ese cou l d causes l e ss t h an 1% eff i ci en cy i m prov ement ov er a hig h er resi stan ce mosfet . figu re 4 - inad equa te ga te en hanceme n t of low resist ance mosfe t
DN94 www .z ete x . c o m 4 i s s u e 1 - n o ve mb e r 20 0 8 www.diodes.com ? diodes incorporated 2008 t o fu rth e r improv e th e cir c u i t , u s e the add i t i onal cir c u i t co mp rising o f q2 , r1 0, r11 a nd r12 in figu re 5. the t r an sistor consta nt curre nt so urce is set u p t o sup p ly t h e bias p i n on the zxgd3 101 in st ea d of a f i x e d va lu e re si sto r . th e va lu e s fo r r1, r 2 a n d r3 are s e l e c t e d t o s o u r ce ap p r ox im at el y 5ma int o t h e ?bias? pin to se t t h e co ntr o lle r ? s thr e shold v o lta g e t o - 2 0 m v . the con s t a n t curr ent source impr ove s the ga te volt age hold u p a f t e r t h e mosfet ? s tur n on in figur e 6 , as a h i g h ga te v o ltag e is desirab l e w h en t h e re ct if ier cir c ula t ing curre nt is high. figu re 5 - consta nt bias cu rren t sou r ce to impr ove gate v o ltage fi gur e 6 - const a n t cur r ent sour ce improv es e nhan ceme n t of low resis t an ce mosfet in a n idea l r e ctif ie r , t h ere should b e no powe r loss in the mosfe t , how eve r , t h er e is mo re t h a n j u st l o w on resi st ance whe n crea ti ng an e f f i ci en t r e cti f i e r . as li ght l o ad an d no lo ad e f f i ci en cy gro w in import a nce , t h e gat e driving loss be come s a se ri ous f a c t or . at low load, pow er loss wi t h in t h e synchr onous rect if ier comprise s of lo sses asso cia t e d wit h bod y diode cond uction, mosfet ga te char ge lo ss as we ll as t h e pow er consumed by th e co ntro ller itself . the d r iv in g loss can be ob taine d fr om t h e p r odu ct of switching f r e quen c y , g a t e charg e va lu e and gat e - s ource v o ltag e. th e b ody diode t u rns o n p r ior t o the ga te t u rn on in t h e synchron ous r e ctifier . th is e n ab le s zer o vo lt ag e tu rn on of th e mosfe t . because of th is sequ ence, th ere i s no vo lt age across the synchr onous swit ch during the t u rn o n t ransition a nd the miller ef fe ct is not pre s e n t. t h ere f or e, t h e e f f e ctiv e ga te charg e can be a ppr oximate d by t h e g a t e dr ain por tion of g a t e cha r ge, q gd subt ract ed fr om t h e t o ta l gate switching charge q g ( to t) . r ref q1 bzt 5 2 c 1 1 s r9 r8 c9 zd 1 q3 10 k 1 f u5 z x g d 3101 fm m t 4 9 1 a1 b1 +12vc c _ s , 50 m a op t i o n # 1 : s yn ch r o n o u s r e ct i f i e r 8. 2 k 100 1k r10 r1 1 r1 2 q2 mmb t 4 1 2 6 re f bias gate l ga t e h g n d dra i n v c c
DN94 is su e 1 - n o ve mb er 20 08 5 www . z e t e x . co m ? diodes incorporated 2008 www.diodes.com anot her side ef fe ct in synchro nous rectif icat ion is th e mosfet out put ca pacita nce c os s on the ad ded sy nchron ous mosfe t intr oduces a stra y cap a cit a n c e , which reson a te s with the t r ansf ormer lea k a g e induct a nce an d le ads to a lar g er v o lt ag e sp ike a t tu rn off . t o ov ercome th is, use rc dampi n g compon ent s i n fi gu re 2 or r e de si gn t h e t r ansf ormer t o red u ce th e vol t age spi ke. v a riat ion of o p era t ing f r eq uency a t f u ll load cou l d a l so be observ e d wit h th e sy nchron ous re ct ifier . th e synchro nous mosfet ca pacita nce is also ref l ecte d across t h e t r an sf ormer and a dds t o the t o t a l o u tp ut capa cit a nce of the p r ima r y switch, the r ef ore r e ducing th e ope rat i n g fre quen c y f r om 67 khz t o 6 0 khz. nev e rt heless, this doe s not de grad e pe rfo r mance o f t h e sy nchron ous re ct i f i e r compar ed wi th di od e recti f icat i on. high per formance rectifier #2 - super barrier rectifier? th e syn c h r onou s rect if ier prov ide s a sign if ica n t ef ficie n cy impro v ment ov er a sch o tt ky d i od e. howe ver if the ex tr a complex i t y of the synchr onous r e ctifie r is not de sira ble, t h e su per barrie r rect if ier? ( sbr?) can be used t o give powe r su pply de sign ers an a dditiona l lev e r t o imp r ove t h e ov era l l e f f i ci ency o f t h ei r po wer sup p l y de sign simp ly by r e placi ng t h e ou tpu t re ct ify i n g diodes. the key to the sbr? techno logy lies in the patented stru ctur e with a mos channel region f o rmed un der t h e t h i n ga te o x i d e l a y e r , fi gu re 7, whe r e t h e ? s u p er? barr ie r fo r ma jo ri ty ( e l e ct ron) carr ie rs is cre a t e d with out t h e unr elia ble sch o tt ky co nta c t . th e ?supe r? ba rrier maint a ins a simila r or be tt er f o rwa r d bias per f orma nce ove r sch o tt ky but with higher reliability . mor e over , the sbr? impr oves the re verse leakage performance. the po ten t i a l ba rri er l o w e ri ng d u e t o t h e i m age charg e , w h ich is ess e nt ia l for the s chot t k y diode, is absent in sb r. the sbr r everse cur r ent is typica l of a p-n diode, where reverse curr ent consists of t h e const a nt injection a nd g r owing io niza tion cu rren t s. this impr ove s t h e r ma l st ab ility of the de vi ce at e l e vat ed t e mper at ure. fi gure 7 - th e l o w vf sbr? t h ere f o r e h a s l o wer fo rwar d vo lt age t h an the compet it i ve sch o tt ky de vi ces i n t h e ma rket , red u cing t h e fo rwar d cond uction lo sses of th e o u tp ut rect if ie rs a nd impro v ing the au xi li a r y powe r su ppl y ef fi cie n cy . evaluation results th e te st re su lt s for t h e se rve r ? s st and b y po wer sup p ly ar e shown in f i gure 7. this part icula r de sign o p er ate s f r om t h e 4 00v pf c rail and p r ovide s t h re e out put s at a co ntinu ous out put p o we r of 27w . the power supply effi cien cy with mbrb30h60ct as the outp u t r e ctifier on the h i g h current +5vsb output is 81.2% at 20% loading and it increase s to 82.8% at full load.
DN94 www .z ete x . c o m 6 i s s u e 1 - n o ve mb e r 20 0 8 www.diodes.com ? diodes incorporated 2008 as de pict ed by figur e 8 , a sy nchro nous mosf et rect if ie r d r i ven by zxgd3 101 dr astically i m prov es th e po wer eff i ci en cy ov er schot tky di ode. th e e f f i ci ency impro veme nt i s af fe cted by the load in g co ndition a nd th e impr ove m e n t is bet w ee n 2 t o 3. 5% at hea vy l o a d co ndi ti on. the improv ement is h i g hly de pend ant on t he sy nchrono us mo sfet resi st an ce . t h e l a r g er eff i ci en cy improv ement can be achieve d w i t h lowe r mosf et r ds(on ) . at f u ll lo ad, t h e powe r supp ly e ffi cie n cy w i t h th e 3. 3 m ? mosf et is aro und 86 %. f i g u re 8 - e f f i ciency compar isons of v a rious rectif ie rs when re pl aci ng th e mbrb3 0 h60 c t scho tt ky di odes wi th the low vf sbr3 0a60 ct dio d es, the ful l l oad ef fi ci ency of th e st andb y powe r supp ly i m prov es f r om 8 2 . 8 % t o 83. 3%. t hi s is a n eff i ci en cy i m prov ement of o ver 0. 5% co mp are d t o t h e sch o tt ky d i o d e. t o e n ab le t h e whol e serv er p o we r supply to achieve complia n ce wit h t h e e n vironm e n t p r ot ection ag ency ( e p a ), blue ang e l an d ot her low powe r syste m re quiremen t , t h e +5 vsb stan dby supply is t y pically r e quire d t o h ave gr eater than 50% efficiency at 100ma load cu rr ent on the +5vsb. the li ght load input supply power with the sbr rectifiers is 830m w which is sim ilar to the schottky diode. as pre v iously d i scusse d , t h e ca pacitive ga te ch ar ge and ic supply relat e d losse s dominat e the condu ct ion loss in the synchro nous re ct ifier at li ght load . when rep l a c ing the sch o tt ky diod e wit h a mosf et, t h e input p o wer o f the p o wer supp ly a t ligh t lo ad incr ease s . to ma in ta in 10 0ma loa d curre nt , th e me asured input powe r of sy nc hrono us re ct ified pow er su pply is 930 mw o r eq ui val en t to 56 % e f f i ci ency . t h i s i s a 10 0mw in crease i n p o we r consumpt i on compa r ed t o bot h sbr and schottky solution s. nevert heless, this is far out weighe d by the sign ificant conductio n loss sav i ng p r ovide d by synchro nous rectif icat ion at n o mina l loa d . con c lusion wit h t h e n e w ener gy sa ving st anda rds set by the ep a an d t h e incre a sin g ad opt ion of th e 80 plus sta nda rd fo r serv er ap plicat ions, t h e design of the st an dby con ver ter wi thi n t h e ser ver p o we r supply is no long er t r ivial, b u t can b e a v e ry tou gh challeng e fo r ma ny p ower su pply de signe rs eq uipped wit h old schot tky t e chnol og y . the z x gd3 1 0 1 synchro nous rect if ier cont rolle r an d the low v f sbr diodes can be used by desi gners as one of the tools to m e et the new stringent effi ciency requirements. th e e x pe rime nta l sta ndby pow er su pply ma nage s t o a c hie ve a d r amat ic 3.5% eff i cien cy improv ement ove r th e schott ky diode s w h en a 3.3m ? r ds(o n) syn c h r onou s mosf et re ct ifier is used on the +5vsb output. the pc boa rd could now be used to prov ide heat sinki ng, eliminating t h e ne ed f o r e x t e rna l h eat sin k , an d remov i n g th e cost of th e he at si nk and asso ci at ed asse mb ly costs. a l ternatively , the low forward voltage sbr30a 60ct enab les designer to achieve 0.5% be tt er eff i ci en cy th an schot t k y wi tho u t ma ki ng any maj o r cha nges t o t h ei r o ver al l desi gn. snub ber compo n ents may n eed to be fitted wh en u s ing the sbr in continu ous condu ction mode conv ert e r t hough t o red u ce emi emission an d f i lt ering re quire me nt. 76 80 84 88 0 5 10 15 20 25 30 ef f i c i e n c y ( % ) irfb3077 fqp65n06 s b r 30a 60c t m b r b 30h60ct o ut put pow e r ( w )
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DN94 www .z ete x . c o m 8 i s s u e 1 - n o ve mb e r 20 0 8 www.diodes.com ? diodes incorporated 2008 sales of fices t h e a m e r icas 305 0 e . hillcr e st drive westlake vi lla g e , ca 91 36 2- 31 54 te l : ( + 1 ) 80 5 4 4 6 48 00 fax : ( + 1) 80 5 446 48 50 eu ro pe kust erm a nn- p ar k b a l a ns tr a? e 59 , d- 81 54 1 m nc hen ge rma n y tel: ( + 4 9 ) 89 4 549 49 0 fa x: (+ 49 ) 89 4 5 4 9 49 49 taiw an 7 f , n o . 50 , min chuan road hsin-tien tai p ei, taiwan tel : ( + 8 8 6 ) 28 9 1 46 00 0 f ax: ( + 8 86) 2 8 9 14 6 6 3 9 shang h ai r m . 60 6, n o .11 5 8 c h angning road s h anghai, china tel : (+8 6 ) 21 5 2 4 1 48 82 fa x (+ 86 ) 2 1 5 24 1 4 8 9 1 sh enzhen a n lia n plaz a, #4 018 jintian road fut ian cbd , shenz h en, china tel: (+ 86 ) 75 5 8 8 2 84 9 8 8 fa x: ( + 86 ) 755 8 82 84 9 99 korea 6 floor, changhwa b/d, 1005- 5 yeongt ong-dong, yeongt ong-gu, suwon-si, gyeonggi-do, korea 443- 81 3 tel : ( + 8 2 ) 3 12 73 1 8 8 4 fa x: (+ 8 2 ) 31 2 7 3 1 88 5 definit i on s pro duct change dio de s inc orpor a t ed the ri ght to alter , without no t i ce, sp e c if icatio ns, d e s i gn, pri ce or co nditi ons of su pply of any pro duct or service. c u stomers ar e sol e l y respo n sib l e for obtaini ng the l a t e st r e le va nt inf o rm a t ion be f o re pl a cing ord e r s. appl icati ons dis claimer the cir cui t s i n t h is desi gn/appl icatio n n o te are offe r e d as desi gn ideas. i t i s t h e r e s ponsi b il ity of the user to e n sure that t he ci rcui t i s fit for the user? s appli cati on and meets with the u ser ? s re q u i r ements. no re present a ti o n or war r a n t y i s gi ven and no l i a bil i t y wha tsoe v er i s assumed by di o d es i n c. wi th r e sp e c t to the accura cy or use of such i n formation , or i n fring e ment of pate n t s o r other in t e ll ectua l pro p er t y ri ghts ari sin g fro m suc h us e or otherwis e . di odes i n c. does not as su me an y le g a l r e sp o n sib i l i ty o r wi ll no t b e h e ld le ga ll y li a bl e ( w h e ther i n contr a ct, tor t (i ncl uding negl igence), br each of stat u t o r y duty , re st ri cti o n or other wise) for any damages, l o ss of pr ofit , busi n ess, contr a c t , opp ortuni t y or c onsequential lo ss i n the u se of these c i rc uit appl icatio ns, under a n y cir cumstances. life sup por t dio d e s zet ex prod ucts are speci f i cally not author ize d f o r use as cri t i cal co m p onents in l i fe suppor t de vi ces or systems witho u t the expr e ss wr it ten a p p r oval o f the chi e f executi ve off i ce r o f di od e s i n cor p o r at ed. as used her e i n : a. li fe sup por t d e vi ce s or systems ar e de vices or systems wh i ch: 1. ar e i n t e nd e d to impl ant into the bod y or 2. supp ort or su sta i n l i fe and whose fail ure to pe r f o r m wh e n prop e r ly us ed in a ccor d a n ce w i th ins t r u ct ion s f o r use p r ov ide d in t he la be ll ing ca n b e re a sona bly ex pe ct e d t o re sul t in sign if ica n t inju ry t o t h e use r . b. a c r itic a l co mponent i s any c o mponent i n a l i fe sup port d e vi ce or system whose f a i l ure t o pe rform can be rea s onably e x pected to cause the f a il ure o f the li f e suppo rt device o r to a ffect i t s safet y o r effe c t i v e n e s s. re p r oduc tion the prod uct specifi cat i ons con t ai ne d i n this pub lic a t i on a r e i ssu ed to provi d e ou t l ine infor m a t i on only whi ch ( u nless agreed by th e company i n wr i t ing) may not be use d , app l i e d or r e pr od uced for any p u r pose or for m pa rt of any or der or contra ct or be re garde d as a representation relating to the p r oduc t s or servic e s con cerned. t e rms and con d iti ons all pro ducts ar e s o ld subj e c t s to dio d es in c. terms a n d con d itio n s of sale , and this discl aime r (sav e in the eve n t o f a confl i c t betwee n t h e two when the te rms of t h e contract shall prevail) a c cord i ng t o region, supplied a t the t i me of order ack nowledgement. fo r the lat e st inf orm at ion on t e chno l o gy , d e live r y t e r m s an d c o ndi tion s a nd pr i c e s , ple a se cont act y our nea r e s t diod es? s a les o ff i c e . q u a l it y of pro duct dio d e s zetex s emiconduc t o rs l i mited is an iso 9 001 and t s 1694 9 certified s e micond uctor ma n u f a cturer . t o ensur e qu a l ity of s e r v ice and prod ucts we strongl y a d vi se th e pur chase of parts dir e c t l y fr om diodes i n c. o r one of our regi onall y authori z ed distr i butor s. f o r a c o mplete li sti ng of author ize d di stribu t o rs p l ease visi t : ww w . d i od e s. com di od es ze te x do es no t w a r r a n t or ac ce pt an y lia bil i ty w h a t so ev er in re sp ec t o f a n y p a rt s p u r ch a s e d th rou g h u n a u t h o r iz ed sa le s c han ne l s. esd (ele ct r o st at i c dischar ge) se mi condu ctor dev i ces a r e su sceptibl e to dama g e by esd . sui t a b le pr ecautions sh ould be t a ken when handli ng and t r a n sporti ng dev ic es . the pos sib l e dama g e t o dev i ces depends on the ci rcums t anc e s of the handli ng and trans portin g, and t h e n a tur e of t h e d e vi ce. the exte n t of dama ge can va ry fr o m imme d i at e functional or par ametr i c mal fun c ti on to degr adati on of functi o n or per f or mance i n u se over ti me . devices suspected o f being af fected s hould be r e p l aced. gr ee n compli ance dio d e s zet ex se mi condu ctors i s commi t t ed to env i ron m ental excell e nc e i n all aspec t s o f i t s operations which i n cl udes mee ti ng or ex c e edi ng regul at or y r e quir e ments wi t h r e s p ect to the use of haz a r dous su bstances. n u merous success f u l pro g rams have been impl e - mente d to r e du ce the us e of haza r dous subs t a nc e s and/ or emis sio ns. all diod e s zet ex compo n ents are co mpl i ant with the rohs d i recti v e, and t h rough t h is i t i s sup portin g its cu stomers in t h e i r co m p lia nc e with weee and e l v di rectives. pr o duct st at u s key: ?pr evi ew? f u t u r e devi ce i n tended for pr o ducti on at some p o i n t. sa mples may be avai l a ble ?active? prod uct status r e commended for new desi gns ?l ast t i me buy (l tb)? dev i ce wi ll be di sconti nued and last time b u y peri od and delivery i s i n effe c t ?not r e commende d for n e w desi gns? dev i ce is sti ll in produ ction t o sup port exis t i ng d e s i gns and p r oduc t i on ?obs olete? prod uction ha s b e en disc ontinued dat a sheet st at us ke y: ?dr a ft ve rsi o n ? thi s t e rm d e n o te s a ver y ea rl y data shee t ver si on and con t ai ns hi ghly pr ov i sio nal infor m a t i on, wh ich ma y change i n any manner without notice. ?provis i onal ve r sio n? this term d e n o te s a pr e- r e l e a s e dat a sh e e t. it provides a cl ea r i ndic a tio n of a n t i cip a ted performance. howeve r , changes t o the test con d itio ns and speci f i cations may occu r , at any time and without notice. ?i ssue ? thi s te rm denote s a n i ssue d dat a sh e e t con t ai n i ng final i zed specifi cati ons. however , changes to specifi cat i ons may occur , at any time and without notice.
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