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c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 1 a n p e c r e s e r v e s t h e r i g h t t o m a k e c h a n g e s t o i m p r o v e r e l i a b i l i t y o r m a n u f a c t u r a b i l i t y w i t h o u t n o t i c e , a n d a d v i s e c u s t o m e r s t o o b t a i n t h e l a t e s t v e r s i o n o f r e l e v a n t i n f o r m a t i o n t o v e r i f y b e f o r e p l a c i n g o r d e r s . 1 . 5 m h z , h i g h e f f i c i e n c y , s t e p - u p c o n v e r t e r w i t h i n t e r n a l f e t s w i t c h f e a t u r e s wide 2.7v to 6v input voltage range built-in 0.2 w n-channel mosfet built-in soft-start high efficiency up to 90% <1 m a quiescent current during shutdown current-mode operation - stable with ceramic output capacitors - fast transient response current-limit protection over-temperature protection with hysteresis available in a tsot-23-5a and tdfn2x2-6 pack- age lead free and green devices available (rohs compliant) a p p l i c a t i o n s g e n e r a l d e s c r i p t i o n t h e a p w 7 2 3 7 i s a f i x e d s w i t c h i n g f r e q u e n c y ( 1 . 5 m h z t y p i c a l ) , c u r r e n t - m o d e , s t e p - u p r e g u l a t o r w i t h a n i n t e - g r a t e d n - c h a n n e l m o s f e t . t h e d e v i c e a l l o w s t h e u s a g e o f s m a l l i n d u c t o r s a n d o u t p u t c a p a c i t o r s f o r p o r t a b l e d e v i c e s . t h e c u r r e n t - m o d e c o n t r o l s c h e m e p r o v i d e s f a s t t r a n s i e n t r e s p o n s e a n d g o o d o u t p u t v o l t a g e a c c u r a c y . t h e a p w 7 2 3 7 i n c l u d e s u n d e r - v o l t a g e l o c k o u t , c u r r e n t - l i m i t , a n d o v e r - t e m p e r a t u r e s h u t d o w n p r e v e n t i n g d a m - a g e i n t h e e v e n t o f a n o u t p u t o v e r l o a d . cell phone and smart phone pda, pmp, mp3 digital camera boost regulators s i m p l i f i e d a p p l i c a t i o n c i r c u i t p i n c o n f i g u r a t i o n supply voltage ( v ) e f f i c i e n c y ( % ) 0 20 40 60 80 100 0 . 01 0 . 1 1 v in = 3 . 3 v v in = 5 v v out = 12 v gnd vin v out 12 v en lx fb l 1 10 m h c 2 4 . 7 m f c 1 4 . 7 m f r 2 137 k w v in 5 v off r 1 1 . 2 m w on apw 7237 tdfn 2 x 2 - 6 top view 1 6 5 4 3 2 vin en gnd lx fb gnd 4 en 5 vin gnd 2 fb 3 lx 1 tsot - 23 - 5 a top view
c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 2 symbol parameter rating unit v in vin pin to gnd - 0.3 to 7 v v lx lx pin to gnd - 0.3 to 22 v v en en pin to gnd - 0.3 to v in v t j maximum junction temperature 150 c t stg storage temperature range - 65 to 150 c t sdr maximum lead soldering temperature, 10 seconds 260 c a b s o l u t e m a x i m u m r a t i n g s ( n o t e 1 ) t h e r m a l c h a r a c t e r i s t i c s symbol parameter typical value unit tsot - 23 - 5a 220 o c/w q ja junction - to - ambient resistance in free air (note 2) tdfn2x2 - 6 165 o c/w tsot - 23 - 5a 120 o c/w q jc junction - to - case resistance tdfn2x2 - 6 20 o c/w o r d e r i n g a n d m a r k i n g i n f o r m a t i o n n o t e : a n p e c l e a d - f r e e p r o d u c t s c o n t a i n m o l d i n g c o m p o u n d s / d i e a t t a c h m a t e r i a l s a n d 1 0 0 % m a t t e t i n p l a t e t e r m i n a t i o n f i n i s h ; w h i c h a r e f u l l y c o m p l i a n t w i t h r o h s . a n p e c l e a d - f r e e p r o d u c t s m e e t o r e x c e e d t h e l e a d - f r e e r e q u i r e m e n t s o f i p c / j e d e c j - s t d - 0 2 0 d f o r m s l c l a s s i f i c a t i o n a t l e a d - f r e e p e a k r e f l o w t e m p e r a t u r e . a n p e c d e f i n e s ? g r e e n ? t o m e a n l e a d - f r e e ( r o h s c o m p l i a n t ) a n d h a l o g e n f r e e ( b r o r c l d o e s n o t e x c e e d 9 0 0 p p m b y w e i g h t i n h o m o g e n e o u s m a t e r i a l a n d t o t a l o f b r a n d c l d o e s n o t e x c e e d 1 5 0 0 p p m b y w e i g h t ) . n o t e 1 : s t r e s s e s b e y o n d t h o s e l i s t e d u n d e r " a b s o l u t e m a x i m u m r a t i n g s " m a y c a u s e p e r m a n e n t d a m a g e t o t h e d e v i c e . t h e s e a r e s t r e s s r a t i n g s o n l y a n d f u n c t i o n a l o p e r a t i o n o f t h e d e v i c e a t t h e s e o r a n y o t h e r c o n d i t i o n s b e y o n d t h o s e i n d i c a t e d u n d e r " r e c o m - m e n d e d o p e r a t i n g c o n d i t i o n s " i s n o t i m p l i e d . e x p o s u r e t o a b s o l u t e m a x i m u m r a t i n g c o n d i t i o n s f o r e x t e n d e d p e r i o d s m a y a f f e c t d e v i c e r e l i a b i l i t y n o t e 2 : q j a i s m e a s u r e d w i t h t h e c o m p o n e n t m o u n t e d o n a h i g h e f f e c t i v e t h e r m a l c o n d u c t i v i t y t e s t b o a r d i n f r e e a i r . apw 7237 handling code temperature range package code assembly material apw 7237 bt : x - date code w 37 x apw 7237 qb : x - date code w 37 x package code bt : 5 lead tsot - 23 qb : tdfn 2 x 2 - 6 operating ambient temperature range i : - 40 to 85 o c handling code tr : tape & reel assembly material g : halogen and lead free device c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 3 r e c o m m e n d e d o p e r a t i n g c o n d i t i o n s ( n o t e 3 ) symbol parameter range unit v in vin input voltage 2.7 ~ 6 v v lx lx to gnd voltage - 0.3 ~ 20 v v out converter output voltage v in ~ 20 v c in input capacitor 2.2 ~ f c out output capacitor 2.2 ~ f t a ambient temperature - 40 ~ 85 c t j junction temp erature - 40 ~ 125 c n o t e 3 : p l e a s e r e f e r t o t h e t y p i c a l a p p l i c a t i o n c i r c u i t . e l e c t r i c a l c h a r a c t e r i s t i c s refer to the typical application circuits. these specifications apply over. v in =3.6v, t a =25c. apw72 37 symbol parameter test condition s min. typ. max. unit supply voltage and current v in input voltage range t a = - 40 ~ 85 c , t j = - 40 ~ 125 c 2.7 - 6 v i dd1 v fb = 1.3v, no switching - 300 - m a i dd2 v fb = 1.1v, swi tching - 2 5 ma i sd input dc bias current en = gnd - - 1 m a under - voltage lockout uvlo threshold voltage v in rising 2.0 2.2 2.4 v uvlo hysteresis voltage 50 100 150 mv reference and output voltages t a = 25 c 1.212 1.23 1.248 v ref regulated feedback voltage t a = - 40 ~ 85 c 1.205 - 1.255 v i fb fb input current v fb =1.23v - 50 - 50 n a internal power switch f sw switching frequency v fb = 1.1 v 1.25 1.5 1.75 mhz r on power switch on resistance - 0.2 - w i lim power switch current limit 2.2 - - a lx leakage current v en =0v, v lx =0v or 5v, v i n = 5v - 1 - 1 m a d max lx maximum duty cycle 92 95 98 % soft - start and shutdown t ss soft - start duration (note 4) - 2 3 ms v ten en voltage threshold v e n rising 0.4 0.7 1 v en voltage hysteresis - 0.1 - v i len en leakage current v en =5v, v i n = 5v - 2 ? 1 +2 m a over - temperature protection t otp over - temperature protection (note 4) t j rising - 150 - c over - temperature protection hysteresis (note 4) - 40 - c n o t e 4 : g u a r a n t e e d b y d e s i g n , n o t p r o d u c t i o n t e s t e d . c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 4 p i n d e s c r i p t i o n pin. t sot - 23 - 5a tdfn - 2x2 - 6 name function 1 6 lx switch pin . connect this pin to inductor/diode here. 2 2, 5 gnd power and signal ground pin. 3 4 fb feedback input. the device senses feedback voltage via fb and regulate the voltage at 1.23 v. connecting fb with a resistor - divider from the output that set s the output voltage. 4 3 en enable control i nput. forcing this pin above 1. 0 v enables the device . forcing this pin below 0. 4 v to shut it down. in shutdown, all f unctions are disabled to decrease the sup ply current below 1 m a. do not left this pin floating. 5 1 vin main s upply pin. must be closely decoupled to gnd with a 2.2 m f or greater ceramic capacitor. c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 5 t y p i c a l o p e r a t i n g c h a r a c t e r i s t i c s output current ( a ) output current vs . efficiency , v out = 5 v e f f i c i e n c y ( % ) 0 20 40 60 80 100 0 . 01 0 . 1 1 v in = 3 . 3 v v in = 4 . 2 v supply voltage ( v ) supply voltage vs . i vin current i v i n c u r r e n t ( m a ) 0 2 4 6 8 2 . 5 3 3 . 5 4 4 . 5 5 5 . 5 6 switching i v i n c u r r e n t ( h a ) supply voltage vs . i vin current supply voltage ( v ) 2 . 5 3 3 . 5 4 4 . 5 5 5 . 5 6 0 50 100 150 200 250 no switching supply voltage vs . switch on resistance s w i t c h o n r e s i s t a n c e ( ? ) supply voltage ( v ) 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 2 2 . 5 3 3 . 5 4 4 . 5 5 5 . 5 6 supply voltage vs . maximum duty cycle m a x i m u m d u t y c y c l e ( % ) supply voltage ( v ) 40 60 80 100 2 . 5 3 3 . 5 4 4 . 5 5 5 . 5 6 output current vs . efficiency , v out = 12 v output current ( a ) e f f i c i e n c y ( % ) 0 20 40 60 80 100 0 . 01 0 . 1 1 v in = 3 . 3 v v in = 5 v v out = 12 v c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 6 t y p i c a l o p e r a t i n g c h a r a c t e r i s t i c s r e f e r e n c e v o l t a g e ( v ) supply voltage vs . reference voltage 1 1 . 05 1 . 1 1 . 15 1 . 2 1 . 25 2 . 5 3 3 . 5 4 4 . 5 5 5 . 5 6 supply voltage ( v ) c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 7 o p e r a t i n g w a v e f o r m s ch 1 : v en ( 2 v / div ) ch 2 : v out ( 2 v / div ) ch 3 : v lx ( 2 v / div ) time : 200 m s / div en goes high - enable , no load 1 2 3 v in = 3 . 3 v , v out = 5 v en goes low - shutdown , io = 100 ma ch 1 : v en ( 2 v / div ) ch 2 : v out ( 2 v / div ) ch 3 : v lx ( 5 v / div ) time : 200 m s / div 1 2 3 v in = 3 . 3 v , v out = 5 v ch 1 : v out ( 2 v / div ) ch 2 : v lx ( 5 v / div ) ch 3 : i l ( 1 a / div ) time : 500 m s / div load transient , io = 50 0 m a - > 1 a - > 500 m a 3 1 , 2 v in = 3 . 3 v , v out = 5 v normal operation ch 1 : v en ( 5 v / div ) ch 2 : v out ( 2 v / div ) ch 3 : v lx ( 5 v / div ) ch 4 : i l ( 1 a / div ) time : 1 m s / div 1 2 3 4 v in = 3 . 3 v , v out = 5 v c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 8 o p e r a t i n g w a v e f o r m s en goes high - enable , no load ch 1 : v en ( 5 v / div ) ch 2 : v lx ( 10 v / div ) ch 3 : v out ( 5 v / div ) time : 500 m s / div v in = 5 v , v out = 12 v 1 2 3 en goes low - shutdown , io = 500 ma ch 1 : v en ( 5 v / div ) ch 2 : v lx ( 10 v / div ) ch 3 : v out ( 5 v / div ) time : 200 m s / div 1 2 3 v in = 5 v , v out = 12 v load transient , io = 10 0 m a - > 500 m a - > 100 m a ch 1 : v en ( 5 v / div ) ch 2 : v out ( 5 v / div ) ch 3 : v lx ( 10 v / div ) ch 4 : i l ( 1 a / div ) time : 500 m s / div 1 2 4 3 v in = 5 v , v out = 12 v normal operation ch 1 : v en ( 5 v / div ) ch 2 : v out ( 2 v / div ) ch 3 : v lx ( 5 v / div ) ch 4 : i l ( 1 a / div ) time : 1 m s / div 1 2 3 , 4 v in = 5 v , v out = 12 v c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 9 b l o c k d i a g r a m uvlo oscillator control logic s vin en fb gnd lx over-temperature protection v ref 1.23v eamp comp i cmp soft-start error amplifier current sense amplifier gate driver current limit slop compensation c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 1 0 t y p i c a l a p p l i c a t i o n c i r c u i t s f i g u r e 1 . t y p i c a l 5 v t o 1 2 v s u p p l y f i g u r e 2 . s t a n d a r d 3 . 3 v t o 5 v s u p p l y f i g u r e 3 . m u l t i p l e o u t p u t f o r t f t - l c d p o w e r s u p p l y gnd vin v out 5 v en lx fb l 1 4 . 7 h c 2 10 m f c 1 4 . 7 m f r 2 140 k w v in off r 1 430 k w on apw 7237 + 9 v + 13 v - 8 v - 4 v c 3 0 . 1 m f c 4 0 . 47 m f c 6 0 . 47 m f c 5 0 . 1 m f c 8 0 . 47 m f c 7 0 . 1 m f c 10 0 . 47 m f c 9 0 . 1 m f gnd vin v out 5 v en lx fb l 1 2 . 2 m h c 2 10 m f c 1 4 . 7 m f r 2 140 k w v in 3 . 3 v off r 1 430 k w on apw 7237 gnd vin v out 12 v en lx fb l 1 4 . 7 m h c 2 4 . 7 m f c 1 4 . 7 m f r 2 137 k w v in 5 v off r 1 1 . 2 m w on apw 7237 c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 1 1 f u n c t i o n d e s c r i p t i o n m a i n c o n t r o l l o o p t h e a p w 7 2 3 7 i s a c o n s t a n t f r e q u e n c y a n d c u r r e n t - m o d e s w i t c h i n g r e g u l a t o r . i n n o r m a l o p e r a t i o n , t h e i n t e r n a l n - c h a n n e l p o w e r m o s f e t i s t u r n e d o n e a c h c y c l e w h e n t h e o s c i l l a t o r s e t s a n i n t e r n a l r s l a t c h , a n d t h e n t u r n e d o f f w h e n a n i n t e r n a l c o m p a r a t o r ( i c m p ) r e s e t s t h e l a t c h . t h e p e a k i n d u c t o r c u r r e n t a t w h i c h i c m p r e s e t s t h e r s l a t c h i s c o n t r o l l e d b y t h e v o l t a g e o n t h e c o m p n o d e w h i c h i s t h e o u t p u t o f t h e e r r o r a m p l i f i e r ( e a m p ) . a n e x t e r n a l r e s i s - t i v e d i v i d e r c o n n e c t e d b e t w e e n v o u t a n d g r o u n d a l l o w s t h e e a m p t o r e c e i v e a n o u t p u t f e e d b a c k v o l t a g e v f b a t f b p i n . w h e n t h e l o a d c u r r e n t i n c r e a s e s , i t c a u s e s a s l i g h t l y t o d e c r e a s e i n v f b a s s o c i a t e d w i t h t h e 1 . 2 3 v r e f e r e n c e , w h i c h i n t u r n , i t c a u s e s t h e c o m p v o l t a g e t o i n c r e a s e u n t i l t h e a v e r a g e i n d u c t o r c u r r e n t m a t c h e s t h e n e w l o a d c u r r e n t . vin under-voltage lockout (uvlo) t h e u n d e r - v o l t a g e l o c k o u t ( u v l o ) c i r c u i t c o m p a r e s t h e i n p u t v o l t a g e a t v i n w i t h t h e u v l o t h r e s h o l d t o e n s u r e t h e i n p u t v o l t a g e i s h i g h e n o u g h f o r r e l i a b l e o p e r a t i o n . t h e 1 0 0 m v ( t y p ) h y s t e r e s i s p r e v e n t s s u p p l y t r a n s i e n t s f r o m c a u s i n g a r e s t a r t . o n c e t h e i n p u t v o l t a g e e x c e e d s t h e u v l o r i s i n g t h r e s h o l d , s t a r t u p b e g i n s . w h e n t h e i n - p u t v o l t a g e f a l l s b e l o w t h e u v l o f a l l i n g t h r e s h o l d , t h e c o n t r o l l e r t u r n s o f f t h e c o n v e r t e r . s o f t - s t a r t t h e a p w 7 2 3 7 h a s a b u i l t - i n s o f t - s t a r t t o c o n t r o l t h e o u t p u t v o l t a g e r i s e d u r i n g s t a r t - u p . d u r i n g s o f t - s t a r t , a n i n t e r n a l r a m p v o l t a g e , c o n n e c t e d t o t h e o n e o f t h e p o s i t i v e i n p u t s o f t h e e r r o r a m p l i f i e r , r a i s e s u p t o r e p l a c e t h e r e f e r e n c e v o l t a g e ( 1 . 2 3 v t y p i c a l ) u n t i l t h e r a m p v o l t a g e r e a c h e s t h e r e f e r e n c e v o l t a g e . c u r r e n t - l i m i t p r o t e c t i o n t h e a p w 7 2 3 7 m o n i t o r s t h e i n d u c t o r c u r r e n t , f l o w s t h r o u g h t h e n - c h a n n e l m o s f e t , a n d l i m i t s t h e c u r r e n t p e a k a t c u r r e n t - l i m i t l e v e l t o p r e v e n t l o a d s a n d t h e a p w 7 2 3 7 f r o m d a m a g i n g d u r i n g o v e r l o a d o r s h o r t - c i r c u i t c o n d i t i o n s . o v e r - t e m p e r a t u r e p r o t e c t i o n ( o t p ) t h e o v e r - t e m p e r a t u r e c i r c u i t l i m i t s t h e j u n c t i o n t e m p e r a - t u r e o f t h e a p w 7 2 3 7 . w h e n t h e j u n c t i o n t e m p e r a t u r e e x - c e e d s 1 5 0 o c , a t h e r m a l s e n s o r t u r n s o f f t h e p o w e r m o s f e t a l l o w i n g t h e d e v i c e s t o c o o l . t h e t h e r m a l s e n - s o r a l l o w s t h e c o n v e r t e r s t o s t a r t a s o f t - s t a r t p r o c e s s a n d r e g u l a t e s t h e o u t p u t v o l t a g e a g a i n a f t e r t h e j u n c t i o n t e m - p e r a t u r e c o o l s b y 4 0 o c . t h e o t p i s d e s i g n e d w i t h a 4 0 o c h y s t e r e s i s t o l o w e r t h e a v e r a g e j u n c t i o n t e m p e r a t u r e ( t j ) d u r i n g c o n t i n u o u s t h e r m a l o v e r l o a d c o n d i t i o n s i n - c r e a s i n g t h e l i f e t i m e o f t h e d e v i c e . e n a b l e / s h u t d o w n d r i v i n g e n t o t h e g r o u n d p l a c e s t h e a p w 7 2 3 7 i n s h u t - d o w n m o d e . w h e n i n s h u t d o w n , t h e i n t e r n a l p o w e r m o s f e t t u r n s o f f , a l l i n t e r n a l c i r c u i t r y s h u t s d o w n , a n d t h e q u i e s c e n t s u p p l y c u r r e n t r e d u c e s t o 1 m a m a x i m u m . c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 1 2 a p p l i c a t i o n i n f o r m a t i o n i n p u t c a p a c i t o r s e l e c t i o n t h e i n p u t c a p a c i t o r ( c i n ) r e d u c e s t h e r i p p l e o f t h e i n p u t c u r r e n t d r a w n f r o m t h e i n p u t s u p p l y a n d r e d u c e s n o i s e i n j e c t i o n i n t o t h e i c . t h e r e f l e c t e d r i p p l e v o l t a g e w i l l b e s m a l l e r w h e n a n i n p u t c a p a c i t o r w i t h l a r g e r c a p a c i t a n c e i s u s e d . f o r r e l i a b l e o p e r a t i o n , i t i s r e c o m m e n d e d t o s e l e c t t h e c a p a c i t o r w i t h m a x i m u m v o l t a g e r a t i n g a t l e a s t 1 . 2 t i m e s o f t h e m a x i m u m i n p u t v o l t a g e . t h e c a p a c i t o r s s h o u l d b e p l a c e d c l o s e t o t h e v i n a n d t h e g n d . i n d u c t o r s e l e c t i o n selecting an inductor with low dc resistance reduces con- duction losses and achieves high efficiency. t h e e f f i c i e n c y i s m o d e r a t e d w h i l s t u s i n g s m a l l c h i p i n d u c t o r which op- erates with h i g h e r i n d u c t o r c o r e l o s s e s . t h e r e f o r e , i t i s n e c e s s a r y t o t a k e f u r t h e r c o n s i d e r a t i o n w h i l e c h o o s i n g a n a d e q u a t e i n d u c t o r . m a i n l y , t h e i n d u c t o r v a l u e d e t e r - m i n e s t h e i n d u c t o r r i p p l e c u r r e n t : l a r g e r i n d u c t o r v a l u e r e s u l t s i n s m a l l e r i n d u c t o r r i p p l e c u r r e n t a n d l o w e r c o n - d u c t i o n l o s s e s o f t h e c o n v e r t e r . h o w e v e r , l a r g e r i n d u c t o r v a l u e g e n e r a t e s s l o w e r l o a d t r a n s i e n t r e s p o n s e . a rea- sonable design rule is to set the ripple current, d i l , to be 30% to 50% of the maximum average inductor current, i l (avg) . the inductor value can be obtained as below, w h e r e v i n = i n p u t v o l t a g e v o u t = o u t p u t v o l t a g e f s w = s w i t c h i n g f r e q u e n c y i n m h z i o u t = m a x i m u m o u t p u t c u r r e n t i n a m p . b = e f f i c i e n c y d i l / i l ( a v g ) = i n d u c t o r r i p p l e c u r r e n t / a v e r a g e c u r r e n t ( 0 . 3 t o 0 . 5 t y p i c a l ) t o a v o i d t h e s a t u r a t i o n o f t h e i n d u c t o r , t h e i n d u c t o r s h o u l d b e r a t e d a t l e a s t f o r t h e m a x i m u m i n p u t c u r r e n t o f t h e c o n v e r t e r p l u s t h e i n d u c t o r r i p p l e c u r r e n t . t h e m a x i m u m i n p u t c u r r e n t i s c a l c u l a t e d a s b e l o w : h = in out ) max ( out ) max ( in v v i i t h e p e a k i n d u c t o r c u r r e n t i s c a l c u l a t e d a s t h e f o l l o w i n g e q u a t i o n : ( ) sw out in out in ) max ( in peak f l v v v v 2 1 i i - + = o u t p u t c a p a c i t o r s e l e c t i o n t h e c u r r e n t - m o d e c o n t r o l s c h e m e o f t h e a p w 7 2 3 7 a l - l o w s t h e u s a g e o f t i n y c e r a m i c c a p a c i t o r s . t h e h i g h e r c a p a c i t o r v a l u e p r o v i d e s g o o d l o a d t r a n s i e n t s r e s p o n s e . c e r a m i c c a p a c i t o r s w i t h l o w e s r v a l u e s h a v e t h e l o w e s t o u t p u t v o l t a g e r i p p l e a n d a r e r e c o m m e n d e d . i f r e q u i r e d , t a n t a l u m c a p a c i t o r s m a y b e u s e d a s w e l l . t h e o u t p u t r i p p l e i s t h e s u m o f t h e v o l t a g e s a c r o s s t h e e s r a n d t h e i d e a l o u t p u t c a p a c i t o r . w h e r e i p e a k i s t h e p e a k i n d u c t o r c u r r e n t . g v o u t = g v e s r + g v c o u t ? ? ? ? ? - ? d sw out in out out out cout f v v v c i v esr peak esr r i v ? d v in v ou t i l n-fet lx i ou t i sw c in c ou t i in d1 esr i lim i l i peak i in i out i sw i d d i l ( ) ? ? ? ? ? d h - ? ? ? ? ? 3 avg l l ) max ( out sw in out 2 out in i i i f v v v v l c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 1 3 a p p l i c a t i o n i n f o r m a t i o n ( c o n t . ) o u t p u t c a p a c i t o r s e l e c t i o n ( c o n t . ) f o r c e r a m i c c a p a c i t o r a p p l i c a t i o n , t h e o u t p u t v o l t a g e r i p p l e i s d o m i n a t e d b y t h e d v c o u t . w h e n c h o o s i n g t h e i n p u t a n d o u t p u t c e r a m i c c a p a c i t o r s , t h e x 5 r o r x 7 r w i t h t h e i r g o o d t e m p e r a t u r e a n d v o l t a g e c h a r a c t e r i s t i c s a r e r e c o m m e n d e d . o u t p u t v o l t a g e s e t t i n g t h e o u t p u t v o l t a g e i s s e t b y a r e s i s t i v e d i v i d e r . t h e e x t e r - n a l r e s i s t i v e d i v i d e r i s c o n n e c t e d t o t h e o u t p u t w h i c h a l - l o w s r e m o t e v o l t a g e s e n s i n g a s s h o w n i n ? t y p i c a l a p p l i - c a t i o n c i r c u i t s ? . a s u g g e s t i o n o f t h e m a x i m u m v a l u e o f r 1 i s 2 m w a n d r 2 i s 2 0 0 k w f o r k e e p i n g t h e m i n i m u m c u r r e n t t h a t p r o v i d e s e n o u g h n o i s e r e j e c t i o n a b i l i t y t h r o u g h t h e r e s i s t o r d i v i d e r . t h e o u t p u t v o l t a g e c a n b e c a l c u l a t e d a s b e l o w : ? ? ? ? ? + = ? ? ? ? ? + = 2 r 1 r 1 23 . 1 2 r 1 r 1 v v ref out d i o d e s e l e c t i o n t o a c h i e v e t h e h i g h e f f i c i e n c y , a s c h o t t k y d i o d e m u s t b e u s e d . t h e c u r r e n t r a t i n g o f t h e d i o d e m u s t m e e t t h e p e a k c u r r e n t r a t i n g o f t h e c o n v e r t e r . layout consideration r 1 r 2 l1 v en v in lx optimized apw7237 layout v out d1 c 2 c 1 f o r a l l s w i t c h i n g p o w e r s u p p l i e s , t h e l a y o u t i s a n i m p o r - t a n t s t e p i n t h e d e s i g n e s p e c i a l l y a t h i g h p e a k c u r r e n t s a n d s w i t c h i n g f r e q u e n c i e s . i f t h e l a y o u t i s n o t c a r e f u l l y d o n e , t h e r e g u l a t o r m i g h t s h o w n o i s e p r o b l e m s a n d d u t y c y c l e j i t t e r . 1 . t h e i n p u t c a p a c i t o r s h o u l d b e p l a c e d c l o s e t o t h e v i n a n d t h e g n d w i t h o u t a n y v i a h o l e s f o r g o o d i n p u t v o l t - a g e f i l t e r i n g . 2 . t o m i n i m i z e c o p p e r t r a c e c o n n e c t i o n s t h a t c a n i n j e c t n o i s e i n t o t h e s y s t e m , t h e i n d u c t o r s h o u l d b e p l a c e d a s c l o s e a s p o s s i b l e t o t h e l x p i n t o m i n i m i z e t h e n o i s e c o u p l i n g i n t o o t h e r c i r c u i t s . 3 . s i n c e t h e f e e d b a c k p i n a n d n e t w o r k i s a h i g h i m p e d - a n c e c i r c u i t t h e f e e d b a c k n e t w o r k s h o u l d b e r o u t e d a w a y f r o m t h e i n d u c t o r . t h e f e e d b a c k p i n a n d f e e d b a c k n e t - w o r k s h o u l d b e s h i e l d e d w i t h a g r o u n d p l a n e o r t r a c e t o m i n i m i z e n o i s e c o u p l i n g i n t o t h i s c i r c u i t . 4 . a s t a r g r o u n d c o n n e c t i o n o r g r o u n d p l a n e m i n i m i z e s g r o u n d s h i f t s a n d n o i s e i s r e c o m m e n d e d . c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 1 4 p a c k a g e i n f o r m a t i o n t s o t - 2 3 - 5 a s y m b o l min. max. 1.00 0.01 0.08 0.22 0.10 a a1 c d e e1 e e1 l millimeters b 0.30 0.50 0.95 bsc tsot-23-5a 0.30 0.60 0.037 bsc min. max. inches 0.039 0.000 0.028 0.035 0.003 0.009 0.012 0.024 0 0.004 a2 0.70 0.90 0.012 0.020 1.90bsc 0.075 bsc 0 8 0 8 1.40 1.80 2.60 3.00 2.70 3.10 0.106 0.122 0.055 0.071 0.102 0.118 note : 1. followed from jedec to-178 aa. 2. dimension d and e1 do not include mold flash, protrusions or gate burrs. mold flash, protrusion or gate burrs shall not exceed 10 mil per side. 0.70 0.028 see view a c e 1 e d e e1 b a a 2 a 1 view a l seating plane gauge plane 0 . 2 5 c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 1 5 p a c k a g e i n f o r m a t i o n t d f n 2 x 2 - 6 s y m b o l min. max. 0.80 0.00 0.18 0.30 1.00 1.60 0.05 0.60 a a1 b d d2 e e2 e l millimeters a3 0.20 ref tdfn2x2-6 0.30 0.45 1.00 0.008 ref min. max. inches 0.031 0.000 0.007 0.012 0.039 0.063 0.024 0.012 0.018 1.90 2.10 0.075 0.083 1.90 2.10 0.075 0.083 0.20 k 0.008 0.70 0.039 0.028 0.002 0.65 bsc 0.026 bsc note : 1. followed from jedec mo-229 wccc. e l k e 2 pin 1 corner d2 a3 a1 b a d e c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 1 6 application a h t1 c d d w e1 f 178.0 ? 2.00 50 min. 8.4+2.00 - 0.00 13.0+0.50 - 0.20 1.5 min. 20.2 min. 8.0 ? 0.30 1.75 ? 0.10 3.5 ? 0.05 p 0 p1 p 2 d 0 d1 t a 0 b 0 k 0 tsot - 23 - 5a 4.0 ? 0.10 4.0 ? 0.10 2.0 ? 0.05 1.5+0.10 - 0.00 1.0 min. 0.6+0.00 - 0 .40 3.20 ? 0.20 3.10 ? 0.20 1.20 ? 0.20 application a h t1 c d d w e1 f 178.0 ? 2.00 50 min. 8.4+2.00 - 0.00 13.0+0.50 - 0.20 1.5 min. 20.2 min. 8.0 ? 0.20 1.75 ? 0.10 3.5 ? 0.05 p 0 p1 p 2 d 0 d1 t a 0 b 0 k 0 tdfn2x2 - 6 4.0 ? 0.10 4.0 ? 0.10 2.0 ? 0.05 1.5+0.10 - 0.00 1.5 min. 0.6+0.00 - 0.40 2.35 ? 0.20 2.35 ? 0.20 1.00 ? 0.20 (mm) c a r r i e r t a p e & r e e l d i m e n s i o n s d e v i c e s p e r u n i t package type unit quantity t sot - 23 - 5 a tape & reel 3000 tdfn2x2 - 6 tape & reel 3000 a e 1 a b w f t p0 od0 b a0 p2 k0 b 0 section b-b section a-a od1 p1 h t1 a d c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 1 7 t a p i n g d i r e c t i o n i n f o r m a t i o n t d f n 2 x 2 - 6 user direction of feed t s o t - 2 3 - 5 a user direction of feed c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 1 8 c l a s s i f i c a t i o n p r o f i l e c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 1 9 c l a s s i f i c a t i o n r e f l o w p r o f i l e s profile feature sn - pb eutectic assembly pb - free assembly preheat & soak temperature min (t smin ) temperature max (t smax ) time (t smin to t smax ) ( t s ) 100 c 150 c 60 - 120 seconds 150 c 200 c 60 - 1 2 0 seconds average ramp - up rate (t smax to t p ) 3 c/second ma x. 3 c/second max. liquidous temperature ( t l ) time at l iquidous (t l ) 183 c 60 - 150 seconds 217 c 60 - 150 seconds peak package body temperature (t p ) * see classification temp in table 1 see classification temp in table 2 time (t p ) ** within 5 c of the spec ified c lassification t emperature ( t c ) 2 0 ** seconds 3 0 ** seconds average r amp - down rate (t p to t smax ) 6 c/second max. 6 c/second max. time 25 c to p eak t emperature 6 minutes max. 8 minutes max. * tolerance for peak profile temperature (t p ) is defined a s a supplier minimum and a user maximum. ** tolerance for time at peak profile temperature (t p ) is defined as a supplier minimum and a user maximum. table 2. pb - free process ? classification temperatures (tc) package thickness volume mm 3 <350 volume mm 3 350 - 2000 volume mm 3 >2000 <1.6 mm 260 c 260 c 260 c 1.6 mm ? 2.5 mm 260 c 250 c 245 c 3 2.5 mm 250 c 245 c 245 c table 1. snpb eutectic process ? classification temperatures (tc) package thickness volume mm 3 <350 volume mm 3 3 350 <2.5 mm 235 c 22 0 c 3 2.5 mm 220 c 220 c test item method description solderability jesd - 22, b102 5 sec, 245 c holt jesd - 22, a108 1000 hrs, bias @ t j =125 c pct jesd - 22, a102 168 hrs, 100 % rh, 2atm , 121 c tct jesd - 22, a104 500 cycles, - 65 c~150 c hbm mil - std - 883 - 3015.7 vhbm ? 2kv mm jesd - 22, a1 15 vmm ? 200v latch - up jesd 78 10ms, 1 tr ? 100ma r e l i a b i l i t y t e s t p r o g r a m c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 2 - d e c . , 2 0 1 2 a p w 7 2 3 7 w w w . a n p e c . c o m . t w 2 0 c u s t o m e r s e r v i c e a n p e c e l e c t r o n i c s c o r p . head office : no.6, dusing 1st road, sbip, hsin-chu, taiwan, r.o.c. tel : 886-3-5642000 fax : 886-3-5642050 t a i p e i b r a n c h : 2 f , n o . 1 1 , l a n e 2 1 8 , s e c 2 j h o n g s i n g r d . , s i n d i a n c i t y , t a i p e i c o u n t y 2 3 1 4 6 , t a i w a n t e l : 8 8 6 - 2 - 2 9 1 0 - 3 8 3 8 f a x : 8 8 6 - 2 - 2 9 1 7 - 3 8 3 8 |
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