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ame 1 AME5251A rev .a.04 dual 1a, 1.5mhz synchronous ste p-down converter the AME5251A is a high ef f iciency monolithic synchro- nous dual buck regulator using a con sta nt frequency , cur- rent mode archite cture. ca pa ble of delivering 1a output cur-rent e a ch cha nnel over a wide in put voltage ra nge from 2.5v to 5.5v . supply current with no loa d is 400 m a a nd drops to<1 m a in shutdown.the 2.5v to 5.5v in put v oltage ra nge ma ke s the AME5251A ide ally suited f or single li-ion battery- powered a pplication s. 100% duty cycle provide s low drop- out operation, extending battery life in portable systems.pwm pulse skipping mode operation provides very low output ri pple voltage f or noise sen sitive a pplication s. at very light loa d, the AME5251A will automatically s ki p pulses in pulse skip mode operation to maintain outputregulation. the intern al synchronous switch incre a se s ef f iciency a nd eli min ate s the need f or a n extern al schottky diode. low output voltage s are e a sily supported with the 0.6v feedba ck reference voltage. the AME5251A is availa ble in small df n-12a pa ck age s. other features include soft start, lower internal refer- ence voltage with 2% a ccura cy , over te mperature prote c- tion, a nd over current prote ction. n general de scri ption n fe ature s n application s n t ypical application l cellular t ele phone s l person al inf ormation appli a nce s l w irele ss a nd dsl mode ms l mps players l portable instruments l high efficiency: up to 95% l shutdown mode draws <1 m a supply current l 2.5v to 5.5v in put ra nge l adjusta ble output from 0.6v to v in l 1a output current per cha nnel l low dropout operation: 100% duty cycle l no schottky diode required l 1.5mhz con sta nt frequency pwm opera tion l small df n-12a pa ck age s l green products meet rohs sta ndard c 2 l 1 o n o f f r 1 c 1 c o u t 1 v o u t 1 v i n 1 c i n 2 r 2 r 3 v o u t 2 r 4 c i n 1 v i n 1 c o u t 2 l 2 i n 2 g n d f b 1 n c 1 e n 1 e n 2 n c 2 f b 2 g n d s w 1 i n 1 a m e 5 2 5 1 a o n o f f s w 2
ame 2 dual 1a, 1.5mhz synchronous ste p-down converter AME5251A rev . a.04 n function block di agra m 0 . 6 v v r e f 0 . 6 v 0 . 5 5 v 4 m o d e s e l e c t s l o p e c o m p s o f t s t a r t o s c u v d e t l o g i c n m o s c o m p i r c o m p v i n e n 1 f b 1 6 9 g n d c o n s t a n t o f f - t i m e 0 . 6 v v r e f 0 . 6 v 0 . 5 5 v 1 0 m o d e s e l e c t s l o p e c o m p s o f t s t a r t o s c u v d e t p w m c o m p l o g i c n m o s c o m p i r c o m p v i n e n 2 f b 2 1 2 1 i n 2 2 s w 2 3 g n d c o n s t a n t o f f - t i m e 7 i n 1 s w 1 8 p w m c o m p
ame 3 AME5251A rev .a.04 dual 1a, 1.5mhz synchronous ste p-down converter AME5251A-a vcxxxxxx 1. in2 2. sw2 3. gnd 4. fb1 5. nc1 6. en1 7. in1 8. sw1 9. gnd 10. fb2 1 1. nc2 12. en2 * die attach: conductive epoxy df n-12a (3mmx3mmx0.75mm) t op v iew n pin configuration note:connect exposed pad (heat sink on the back) to gnd. n pin de scri ption p i n n a m e p i n d e s c r i p t i o n n c n o c o n n e c t i o n . n o t i n t e r n a l l y c o n n e c t e d . c a n l e f t f l o a t i n g o r c o n n e c t e d t o g n d . e n e n a b l e c o n t r o l i n p u t , a c t i v e h i g h . i n i n p u t s u p p l y v o l t a g e p i n . b y p a s s t h i s p i n w i t h a c a p a c i t o r a s c l o s e t o t h e d e v i c e a s p o s s i b l e . s w s w i t c h n o d e c o n n e c t i o n t o i n d u c t o r . g n d g r o u n d . t i e d i r e c t l y t o g r o u n d p l a n e . f b o u t p u t v o l t a g e f e e d b a c k i n p u t . a m e 5 2 5 1 a 1 2 3 4 5 6 1 2 1 1 1 0 9 8 7
ame 4 dual 1a, 1.5mhz synchronous ste p-down converter AME5251A rev . a.04 n ordering information AME5251A - x x x xxx xxx p i n c o n f i g u r a t i o n & s p e c i a l f e a t u r e p a c k a g e t y p e n u m b e r o f p i n s o u t p u t v o l t a g e 1 o u t p u t v o l t a g e 2 a 1 i n 2 v : d f n c : 1 2 a d j : a d j u s t a b l e a d j : a d j u s t a b l e ( d f n - 1 2 a ) 2 . s w 2 3 . g n d 4 . f b 1 5 . n c 1 6 . e n 1 7 . i n 1 8 . s w 1 9 . g n d 1 0 . f b 2 1 1 . n c 2 1 2 . e n 2 p i n c o n f i g u r a t i o n & s p e c i a l f e a t u r e p a c k a g e t y p e n u m b e r o f p i n s o u t p u t v o l t a g e 1 o u t p u t v o l t a g e 2
ame 5 AME5251A rev .a.04 dual 1a, 1.5mhz synchronous ste p-down converter n absolute m axi mum ratings caution: stre ss a bove the listed a bsolute maxi mum rating may cause perma nent da mage to the device. * hbm b: 2000v~3999v p a r a m e t e r s y m b o l m a x i m u m u n i t i n p u t s u p p l y v o l t a g e v i n - 0 . 3 t o 6 . 5 e n , v o u t v o l t a g e v e n , v o u t - 0 . 3 t o v i n s w v o l t a g e v s w - 0 . 3 t o v i n e s d c l a s s i f i c a t i o n v b * n thermal information * me a sure q jc on ba ck side center of exposed pa d. ** mil-st d-202g 210f n re commended operating condition s p a r a m e t e r s y m b o l r a t i n g u n i t s u p p l y v o l t a g e v o l t a g e v i n 2 . 5 t o 5 . 5 v a m b i e n t t e m p e r a t u r e r a n g e t a - 4 0 t o + 8 5 o c j u n c t i o n t e m p e r a t u r e r a n g e t j - 4 0 t o + 1 2 5 o c p a r a m e t e r p a c k a g e d i e a t t a c h s y m b o l m a x i m u m u n i t t h e r m a l r e s i s t a n c e * ( j u n c t i o n t o c a s e ) q j c 8 . 5 t h e r m a l r e s i s t a n c e ( j u n c t i o n t o a m b i e n t ) q j a 6 5 i n t e r n a l p o w e r d i s s i p a t i o n p d 1 . 5 4 w 3 5 0 o c o c / w s o l d e r i r o n ( 1 0 s e c ) * * c o n d u c t i v e e p o x y d f n - 1 2 a
ame 6 dual 1a, 1.5mhz synchronous ste p-down converter AME5251A rev . a.04 n ele ctrical spe cif ication s v in =3.6v , v out =2.5v , v fb =0.6v , l=2.2 m h, c in =4.7 m f , c out =10 m f , t a =25 o c, i max =1a unle ss otherwise spe cif ied. note 1. spe c. f or per cha nnel p a r a m e t e r s y m b o l m i n t y p m a x u n i t s i n p u t v o l t a g e v i n 2 . 5 5 . 5 v a d j u s t a b l e o u t p u t r a n g e v o u t v f b v i n - 0 . 2 v f e e d b a c k v o l t a g e v f b 0 . 5 8 8 0 . 6 0 . 6 1 2 v f e e d b a c k p i n b i a s c u r r e n t i f b - 5 0 5 0 n a q u i e s c e n t c u r r e n t i q 0 . 4 0 . 5 m a s h u t d o w n c u r r e n t i s h d n 0 . 1 1 m a s w i t c h f r e q u e n c y f o s c 1 . 2 1 . 5 1 . 8 m h z h i g h - s i d e s w i t c h o n - r e s i s t a n c e r d s , o n , l h i 0 . 2 8 w l o w - s i d e s w i t c h o n - r e s i s t a n c e r d s , o n , l o 0 . 2 5 w s w i t c h c u r r e n t l i m i t i s w , c l 1 . 4 1 . 6 a e n h i g h ( e n a b l e d t h e d e v i c e ) v e n , h i 1 . 5 v e n l o w ( s h u t d o w n t h e d e v i c e ) v e n , l o 0 . 4 v i n p u t u n d e r v o l t a g e l o c k o u t v u v l o 1 . 8 v i n p u t u n d e r v o l t a g e l o c k o u t h y s t e r e s i s v u v l o , h y s t 0 . 1 v t h e r m a l s h u t d o w n t e m p e r a t u r e o t p 1 6 0 o c m a x i m u m d u t y c y c l e d m a x 1 0 0 % s w l e a k a g e c u r r e n t - 1 1 m a e n = 0 v , v i n = 5 . 0 v v s w = 0 v o r 5 . 0 v t e s t c o n d i t i o n i s w = 2 0 0 m a , v i n = 3 . 6 v f o r a d j u s t a b l e o u t p u t v o l t a g e v f b = v i n i o u t = 0 m a , v f b = 1 v v i n = 2 . 5 t o 5 . 5 v r i s i n g e d g e s h u t d o w n , t e m p e r a t u r e i n c r e a s i n g v e n = g n d i s w = 2 0 0 m a , v i n = 3 . 6 v v i n = 2 . 5 t o 5 . 5 v v i n = 2 . 5 t o 5 . 5 v
ame 7 AME5251A rev .a.04 dual 1a, 1.5mhz synchronous ste p-down converter n detailed de scri ption main control loopAME5251A use s a con sta nt frequency , current mode ste p-down archite cture. both the main (p-cha nnel mosfet) a nd synchronous (n-cha nnel mosfet) switche s are intermal. during normal operation, the in- tern al top power mosfet is turned on e a ch cycle when the oscillator sets the rs latch, a nd turned of f when the current comparator resets the rs latch. while the topmosfet is off, the bottom mosfet is turned on until e ither the inductor current starts to reverse a s indicated by the current reversal comparator ircmp . pulse skipping mode operationat light loa ds, the inductor current may re a ch zero or reverse on e a ch pulse.the bottom mosfet is turned of f by the current reversal comparator , ircmp , a nd the switch voltage will ring. this is discontinuous mode operation,a nd is normal behavior f or the switching regulator . short-circuit protectionwhen the output is shorted to ground, the frequency of the oscillator is reduced to about 180khz. this frequencyf oldba ck en sure s that the inductor current hsa more ti me do de cay , thereby preventing run away . the oscillator ? s frequency will progre ssively incre a se to 1.5mhz when v fb or v out rise s a bole 0v . dropout operationas the in put supply voltage de cre a se s to a value a p- proa ching the output voltage, the duty cycle incre a se s toward the maximum on-time. further reduction of thesupply voltage forces the main switch to remain on for more tha n one cycle until it re a che s 100% duty cycle. the output voltage will then be determined by the inputvoltage minus the voltage drop a cross the p-cha nnel mosfet a nd the inductor . n applincation inf ormation the ba sic AME5251A a pplication circuit is shown in t ypical application circuit. extern al component sele c- tion is determined by the maxi mum loa d current a nd be- gin s with the sele ction of the inductor value a nd f ollowed by c in a nd c out . inductor selectionfor a given in put a nd output voltage, the inductor value a nd operating frequency determine the ri pple current. the ri pple current dil incre a se s with higher v in a nd de cre a se s with higher inducta nce. a re a son a ble starting point f or setting ri pple current is d il=0.4(lmax). the dc current rating of the inductor should be at le a st equal to the maxi mum loa d current plus hal f the ripple current to prevent core saturation. for betteref f iciency , choose a low dc-re sista nce inductor . c in and c out selection the in put ca pa cita nce, c in is needed to f ilter the tra p- ezoidal current at the source of the top mosfet . t o prevent large voltage tra n sients, a low esr in put ca pa citorsized f or the maxi mum rms current must be used. the maxi mum rms ca pa citor current is given by: 1 ) ( - = o u t i n i n o u t m a x o u t r m s v v v v i i ( ) ( ) - = d i n o u t o u t l v v v l f i 1 1
ame 8 dual 1a, 1.5mhz synchronous ste p-down converter AME5251A rev . a.04 this f ormula ha s a maxi mum at v in =2v out , where irms=i out /2. this si mple worst-ca se condition is com- monly used f or de sign be cause even signif ica nt devi a- tion s do not of fer much relief. note that the ca pa citor ma nufa cturer ri pple current ratings are often ba sed on 2000 hours of life. this ma ke s it a dvisa ble to further derate the ca pa citor , or choose a ca pa citor rated at a higher te mperature tha n required. the selection of c out is determined by the effective serie s re sista nce(esr) that is required to mini mize volt- age ri pple a nd loa d ste p tra n sients. the output ri pple, v out , is determined by: using cera mic in put a nd output ca pa citors higher value s, lower cost cera mic ca pa citors are now be coming availa ble in smaller ca se size s. the ir high ri pple current, high voltage rating a nd low esr ma ke the m ide al f or switching regulator a pplication s. however , care must be ta ken when the se ca pa citors are used at the in put a nd output. when a cera mic ca pa citor is used at the in put a nd the power is supplied by a wall a da pter through long wire s, a loa d ste p at the output ca n induce ringing at the in put, v in . at be st, this ringing ca n couple to the output a nd be mista ken a s loop in sta bility . at worst, a sudden inrush of current through the long wire s ca n potentially cause a voltage spike at v in large enough to da mage the part. output v oltage progra mming the output voltage is set by a n extern al re sistive di- vider a ccording to the f ollowing equation: where vref equals to 0.6v typical. the resistive di- vider allows the fb pin to sen se a fra ction of the output voltage a s shown in figure 1. + d @ d o u t l o u t f c e s r i v 8 1 + = 2 1 1 r r v v r e f o u t a m e 5 2 5 1 a f b g n d r 1 r 2 0 . 6 v v o u t 5 . 5 v figure 1: setting the AME5251A output v oltage thermal considerationsin most a pplication s the AME5251A doe s not dissi- pate much he at due to its high ef f iciency . but, in a ppli- cation s where the AME5251A is running at high a mbient te mperature with low supply voltage a nd high duty cycle s, such a s in dropout, the he at dissi pated may exceed the maximum junction temperature of the part. if the junctionte mperature re a che s a pproxi mately 160 o c, both power switche s will be turned of f a nd the sw node will be come high i mpeda nce. t o avoid the AME5251A from exceed- ing the maximum junction temperature, the user will needto do some thermal a n alysis. the goal of the thermal a n alysis is to determine whether the power dissi pated exceeds the maximum junction temperature of the part.the temperature rise is given by: where pd is the power dissi pated by the regulator a nd q ja is the thermal re sista nce from the junction of the die to the a mbient te mperature. ( ) ( ) j a r p d t q =
ame 9 AME5251A rev .a.04 dual 1a, 1.5mhz synchronous ste p-down converter figure 2: 1.2v step-down regulator c fw d : 22pf~220pf figure 3: 1.5v step-down regulator c fw d : 22pf~220pf figure 4: 1.6v step-down regulator c fw d : 22pf~220pf figure 5: 2.5v step-down regulator c fw d : 22pf~220pf figure 6: 3.3v step-down regulator c fw d : 22pf~220pf v i n 2 . 5 v t o 5 . 5 v s w f b g n d i n e n a m e 5 2 5 1 a c i n 4 . 7 m f c e r 1 5 0 k 1 5 0 k v o u t 1 . 2 v c o u t 1 0 m f c e r 2 . 2 m h c f w d c o u t 1 0 m f c e r s w f b g n d i n e n a m e 5 2 5 1 a v i n 3 . 3 t o 5 . 5 v c i n 4 . 7 m f c e r 1 5 0 k 1 0 0 k v o u t 1 . 5 v 2 . 2 m h c f w d s w f b g n d i n e n a m e 5 2 5 1 a v i n 2 . 5 t o 5 . 5 v c i n 4 . 7 m f c e r 1 5 0 k 9 0 k v o u t 1 . 6 v c o u t 1 0 m f c e r 2 . 2 m h c f w d s w f b g n d i n e n a m e 5 2 5 1 a v i n 2 . 7 v t o 5 . 5 v c i n 4 . 7 m f c e r 1 5 0 k 4 7 . 3 k v o u t 2 . 5 v c o u t 1 0 m f c e r 2 . 2 m h c f w d s w f b g n d i n e n a m e 5 2 5 1 a v i n 3 . 6 t o 5 . 5 v c i n 4 . 7 m f c e r 1 5 0 k 3 3 . 3 k v o u t 3 . 3 v c o u t 1 0 m f c e r 2 . 2 m h c f w d
ame 10 dual 1a, 1.5mhz synchronous ste p-down converter AME5251A rev . a.04 pc board layout checklist when laying out the printed circuit board, the following checklist should be used to ensure proper operation of the AME5251A. check the following in your layout: 1. the power tra ce s, con sisting of the gnd tra ce, the sw tra ce a nd the v in tra ce should be ke pt short, dire ct a nd wide. 2. doe s the v fb pin conne ct dire ctly to the feedba ck re sistors? the re sistive divider r2/r1 must be conne cted between the (+) plate of c out a nd ground. 3. doe s the (+) plate of cin conne ct to v in a s closely a s possible? this ca pa citor provide s the ac current to the intern al power mosfet s. 4. kee p the switching node, sw , away from the sen sitive v fb node. 5. kee p the (-) plate s of c in a nd c out a s close a s possible. figure 7: AME5251A adjusta ble v oltage regulator layout di agra m 2 3 1 2 1 1 1 0 s w 2 g n d e n 2 n c 2 f b 2 c i n 1 , c i n 2 s h o u l d b e p l a c e d b e t w e e n v i n a n d g n d a s c l o s e a s p o s s i b l e . r 1 1 , r 1 2 , r 2 1 , r 2 2 a n d c 1 1 , c 2 1 m u s t b e k e p t c l o s e t o t h e i c s f b p i n t o p r e v e n t n o i s e i n j e c t i o n o n t h e f b p i n t r a c e a n d k e e p i n g f a r a w a y f r o m s w n o d e . a m e 5 2 5 1 a v i n 2 1 g n d 98 7 g n d s w 1 v i n 1 f b 1 n c 1 e n 1 45 6 t h e g r o u n d a r e a m u s t p r o v i d e a d e q u a t e h e a t d i s s i p a t i n g a r e a t o t h e t h e r m a l p a d a n d u s i n g m u l t i p l e v i a s t o h e l p t h e r m a l d i s s i p a t i o n . n c 1 , n c 2 p i n n o c o n n e c t o r c o n n e c t t o g n d . r 2 1 r 2 2 c 2 1 l 1 c o u t 1 c i n 1 c i n 2 c o u t 2 l 2 r 1 2 r 1 1 c 1 1 s w 1 , s w 2 s h o u l d b e c o n n e c t e d t o i n d u c t o r b y w i d e a n d s h o r t t r a c e . k e e p s e n s i t i v e c o m p o n e n t s a w a y f r o m t h i s t r a c e . v o u t 1 v o u t 1 v o u t 2 v o u t 2
ame 11 AME5251A rev .a.04 dual 1a, 1.5mhz synchronous ste p-down converter n application inf ormation t a ble 1. re commended inductors t a ble 2. re commended ca pa citors f or c in a nd c out s u p p l i e r i n d u c t a n c e ( m m m m h ) c u r r e n t r a t i n g ( m a ) d c r ( m w w w w ) d i m e n s i o n s ( m m ) s e r i e s t a i y o y u d e n 2 . 2 1 4 8 0 6 0 3 . 0 0 x 3 . 0 0 x 1 . 5 0 n r 3 0 1 5 g o t r e n d 2 . 2 1 5 0 0 5 8 3 . 8 5 x 3 . 8 5 x 1 . 8 0 g t s d 3 2 s u m i d a 2 . 2 1 5 0 0 7 5 4 . 5 0 x 3 . 2 0 x 1 . 5 5 c d r h 2 d 1 4 s u m i d a 4 . 7 1 0 0 0 1 3 5 4 . 5 0 x 3 . 2 0 x 1 . 5 5 c d r h 2 d 1 4 t a i y o y u d e n 4 . 7 1 0 2 0 1 2 0 3 . 0 0 x 3 . 0 0 x 1 . 5 0 n r 3 0 1 5 g o t r e n d 4 . 7 1 1 0 0 1 4 6 3 . 8 5 x 3 . 8 5 x 1 . 8 0 g t s d 3 2 external components selection
ame 12 dual 1a, 1.5mhz synchronous ste p-down converter AME5251A rev . a.04 n chara cterization curve efficiency vs. output current efficiency vs. output current efficiency vs. output current efficiency vs. output current efficiency vs. output current efficiency vs. output current o u t p u t c u r r e n t ( m a ) e f f i c i e n c y ( % ) 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 0 0 1 0 0 0 v i n = 2 . 7 v v o u t = 2 . 5 v c o u t = 1 0 m f l = 2 . 2 m h 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 0 0 1 0 0 0 o u t p u t c u r r e n t ( m a ) e f f i c i e n c y ( % ) v i n = 3 . 6 v v o u t = 2 . 5 v c o u t = 1 0 m f l = 2 . 2 m h o u t p u t c u r r e n t ( m a ) 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 0 0 1 0 0 0 e f f i c i e n c y ( % ) v i n = 2 . 7 v v o u t = 1 . 5 v c o u t = 1 0 m f l = 2 . 2 m h o u t p u t c u r r e n t ( m a ) 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 0 0 1 0 0 0 e f f i c i e n c y ( % ) v i n = 3 . 6 v v o u t = 1 . 5 v c o u t = 1 0 m f l = 2 . 2 m h o u t p u t c u r r e n t ( m a ) e f f i c i e n c y ( % ) 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 0 0 1 0 0 0 v i n = 2 . 5 v v o u t = 1 . 2 v c o u t = 1 0 m f l = 2 . 2 m h 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 0 0 1 0 0 0 o u t p u t c u r r e n t ( m a ) e f f i c i e n c y ( % ) v i n = 5 . 5 v v o u t = 1 . 2 v c o u t = 1 0 m f l = 2 . 2 m h
ame 13 AME5251A rev .a.04 dual 1a, 1.5mhz synchronous ste p-down converter n chara cterization curve (contd.) reference v oltage vs. t e mperature frequency vs. t e mperature frequency vs. supply v oltage output v oltage vs. output current current li mit vs. t e mperature current li mit vs. t e mperature 1 . 3 1 . 4 1 . 5 1 . 6 1 . 7 1 . 8 1 . 9 2 . 0 2 . 1 2 . 2 2 . 3 2 . 4 2 . 5 2 . 6 2 . 7 2 . 8 2 . 9 3 . 0 - 4 0 - 2 5 - 1 0 + 5 + 2 0 + 3 5 + 5 0 + 6 5 + 8 0 + 9 5 + 1 1 0 + 1 2 5 c u r r e n t l i m i t ( a ) t e m p e r a t u r e ( o c ) v i n = 3 . 3 v v o u t = 1 . 2 v 1 . 3 1 . 4 1 . 5 1 . 6 1 . 7 1 . 8 1 . 9 2 . 0 2 . 1 2 . 2 2 . 3 2 . 4 2 . 5 2 . 6 2 . 7 2 . 8 2 . 9 3 . 0 - 4 0 - 2 5 - 1 0 + 5 + 2 0 + 3 5 + 5 0 + 6 5 + 8 0 + 9 5 + 1 1 0 + 1 2 5 c u r r e n t l i m i t ( a ) t e m p e r a t u r e ( o c ) v i n = 3 . 6 v v o u t = 1 . 2 v 0 . 5 8 0 0 . 5 8 5 0 . 5 9 0 0 . 5 9 5 0 . 6 0 0 0 . 6 0 5 0 . 6 1 0 0 . 6 1 5 0 . 6 2 0 - 5 0 - 2 5 0 + 2 5 + 5 0 + 7 5 + 1 0 0 + 1 2 5 r e f e r e n c e v o l t a g e ( v ) t e m p e r a t u r e ( o c ) v i n = 3 . 6 v 1 . 1 0 1 . 1 5 1 . 2 0 1 . 2 5 1 . 3 0 1 . 3 5 1 . 4 0 1 . 4 5 1 . 5 0 1 . 5 5 1 . 6 0 1 . 6 5 1 . 7 0 1 . 7 5 1 . 8 0 1 . 8 5 1 . 9 0 - 5 0 - 2 5 + 0 + 2 5 + 5 0 + 7 5 + 1 0 0 + 1 2 5 f r e q u e n c y ( m h z ) t e m p e r a t u r e ( o c ) v i n = 3 . 6 v 1 . 7 7 1 . 7 8 1 . 7 9 1 . 8 0 1 . 8 1 1 . 8 2 1 . 8 3 1 . 8 4 1 . 8 5 1 . 8 6 1 . 8 7 1 . 8 8 1 . 8 9 1 . 9 0 0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0 7 0 0 8 0 0 9 0 0 1 0 0 0 o u t p u t c u r r e n t ( m a ) o u t p u t v o l t a g e ( v ) v o u t = 1 . 8 v v i n = 3 . 6 v 1 . 1 0 1 . 1 5 1 . 2 0 1 . 2 5 1 . 3 0 1 . 3 5 1 . 4 0 1 . 4 5 1 . 5 0 1 . 5 5 1 . 6 0 1 . 6 5 1 . 7 0 2 . 5 3 . 0 3 . 5 4 . 0 4 . 5 5 . 0 5 . 5 v i n ( v ) f r e q u e n c y ( m h z )
ame 14 dual 1a, 1.5mhz synchronous ste p-down converter AME5251A rev . a.04 n chara cterization curve (contd.) light loa d mode output v oltage ri pple v in = 3.6v v out = 1.2v i out = 50ma 1) v sw = 2v/div 2) v out = 10mv/div 3) i l = 500ma/div load step v in = 3.6v v out = 1.8v i out = 0a~1a~0a 1) v out = 100mv/div 2) i out = 500ma/div current li mit vs. t e mperature 1 . 3 1 . 4 1 . 5 1 . 6 1 . 7 1 . 8 1 . 9 2 . 0 2 . 1 2 . 2 2 . 3 2 . 4 2 . 5 2 . 6 2 . 7 2 . 8 2 . 9 3 . 0 - 4 0 - 2 5 - 1 0 + 5 + 2 0 + 3 5 + 5 0 + 6 5 + 8 0 + 9 5 + 1 1 0 + 1 2 5 c u r r e n t l i m i t ( a ) t e m p e r a t u r e ( o c ) v i n = 5 . 0 v v o u t = 1 . 2 v he avy loa d mode output v oltage ri pple v in = 3.6v v out = 1.2v i out = 1a 1) v sw = 2v/div 2) v out = 10mv/div 3) i l = 500ma/div 4 0 0 n s / d i v 23 1 12 3 4 0 0 n s / d i v
ame 15 AME5251A rev .a.04 dual 1a, 1.5mhz synchronous ste p-down converter n chara cterization curve (contd.) load step v in = 3.6v v out = 1.8v i out = 200ma~1a~200ma 1) v out = 100mv/div 2) i out = 500ma/div load step v in = 3.6v v out = 1.8v i out = 50ma~1a~50ma 1) v out = 100mv/div 2) i out = 500ma/div power on from en v out = 1.2v i out = 1a 1) en = 2v/div 2) v out = 500mv/div 3) i l = 1a/div power off from en v in = 3.6v v out = 1.8v i out = 1a 1) en = 2v/div 2) v out = 2v/div 3) i l = 500ma/div
ame 16 dual 1a, 1.5mhz synchronous ste p-down converter AME5251A rev . a.04 n t a pe a nd reel di men sion carrier t a pe, number of components per reel a nd reel size df n-12a (3mmx3mmx0.75mm) w p p i n 1 a m e a m e p a c k a g e c a r r i e r w i d t h ( w ) p i t c h ( p ) p a r t p e r f u l l r e e l r e e l s i z e d f n - 1 2 a ( 3 x 3 x 0 . 7 5 m m ) 1 2 . 0 0 . 1 m m 4 . 0 0 . 1 m m 5 0 0 0 p c s 3 3 0 1 m m
ame 17 AME5251A rev .a.04 dual 1a, 1.5mhz synchronous ste p-down converter n pa ck age di men sion df n-12a (3mmx3mmx0.75mm) t o p v i e w b o t t o m v i e w e d l p i n 1 k e b d 1 e 1 r e a r v i e w a a 3 a 1 p i n 1 i d e n t i f i c a t i o n m i n m a x m i n m a x a 0 . 7 0 0 0 . 8 0 0 0 . 0 2 8 0 . 0 3 1 a 1 0 . 0 0 0 0 . 0 5 0 0 . 0 0 0 0 . 0 0 2 a 3 d 2 . 9 2 4 3 . 0 7 6 0 . 1 1 5 0 . 1 2 1 e 2 . 9 2 4 3 . 0 7 6 0 . 1 1 5 0 . 1 2 1 d 1 2 . 4 5 0 2 . 6 5 0 0 . 0 9 6 0 . 1 0 4 e 1 1 . 5 0 0 1 . 7 0 0 0 . 0 5 9 0 . 0 6 7 k b 0 . 1 5 0 0 . 2 5 0 0 . 0 0 6 0 . 0 1 0 el 0 . 3 2 4 0 . 4 7 6 0 . 0 1 3 0 . 0 1 9 s y m b o l s m i l l i m e t e r s i n c h e s 0 . 2 0 3 r e f . 0 . 0 0 8 r e f . 0 . 2 0 0 m i n . 0 . 4 5 0 t y p . 0 . 0 0 8 m i n 0 . 0 1 8 t y p .
ame 18 dual 1a, 1.5mhz synchronous ste p-down converter AME5251A rev . a.04 n le a d pattern note:1. lead pattern unit description: bsc: ba sic. re pre sents theoretical exa ct di men sion or di men sion target. 2. di men sion s in m illi meters. 3. general tolera nce + 0.05mm unle ss otherwise spe cif ied. df n-12a (3mmx3mmx0.75mm) 2 . 7 5 0 b s c 0 . 0 0 0 b s c 1 . 0 5 0 b s c p i n 1 [ 1 ] 0 . 4 5 0 b s c 0 . 2 5 0 b s c 1 . 8 0 0 b s c 0 . 0 0 0 b s c 1 . 3 7 5 b s c 3 x 3 p k g r e f .
life support policy: the se products of ame, inc. are not authorized f or use a s critical components in life-support device s or syste ms, without the expre ss written a pproval of the pre sident of ame, inc. ame, inc. re serve s the right to ma ke cha nge s in the circuitry a nd spe cif ication s of its device s a nd a dvise s its customers to obtain the late st version of releva nt inf ormation. ? ame, inc. , ja nuary 2014 document: 1283-ds5251a-a.04 corporate he a dquarter ame, inc.8f , 12, w enhu st., ne i-hu t ai pe i 1 14, t aiwa n. t el: 886 2 2627-8687 fax: 886 2 2659-2989 www .a me.com.tw e-m ail: sale s@a me.com.tw

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