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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 - a u g . , 2 0 1 3 a p w 7 3 1 4 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 . 2 4 v 2 a 5 0 0 k h z s y n c h r o n o u s b u c k c o n v e r t e r f e a t u r e s g e n e r a l d e s c r i p t i o n wide input voltage from 4.5v to 24v 2a continuous output current adjustable output voltage from 0.807v to 13v integrated low rds(on) mosfets fixed 500khz switching frequency over-temperature protection current-limit protection with hiccup mode small tsot-23-8a package lead free and green devices available (rohs compliant) a p p l i c a t i o n s lcd monitor/tv set-top box dsl, switch hub notebook computer apw7314 is a 2a synchronous buck converter with inte- grated low rds(on) power mosfets. the apw7314 de- sign with a current-mode control scheme, can convert wide input voltage of 4.5v to 24v to the output voltage adjustable from 0.807v to 13v to provide excellent output voltage regulation. the apw7314 is also equipped with under-voltage lockout, soft-start, over-temperature and current-limit pro- tection into a single package. this device, available tsot-23-8a, provides a very com- pact system solution external components and pcb area. 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 6 en 8 fb vin 2 7 vcc iset 1 apw 7314 t sot - 23 - 8 a 5 bst gnd 4 sw 3 vin v cc iset en off on v in 4 . 5 v ~ 24 v sw fb gnd apw 7314 v out c out 47 m f bst
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 - a u g . , 2 0 1 3 a p w 7 3 1 4 w w w . a n p e c . c o m . t w 2 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 ) . 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 ) symbol parameter rating unit v in vin supply to gnd voltage - 0.3 ~ 27 v v sw sw to gnd voltage - 0.3 ~ 27 v v bst - sw bst to sw voltage - 0.3 ~ 6 v iset, en, vcc and fb to gnd voltage - 0.3 ~ 6 v t j junction temperature 150 o c t stg storage temperature - 65 ~ 150 o c t sdr maximum lead soldering temperature ( 10 seconds ) 26 0 o c note1: stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. these are stress ratings only and functional operation of the device at these or any other conditions beyond those indicated under "recom- mended operating conditions" is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability 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 q ja junction - to - ambient resistance in f ree a ir (note 2) 220 o c/w note 2: q ja is measured with the component mounted on a high effective thermal conductivity test board in free air. symbol parameter range unit v in vin supply voltage 4.5 ~ 24 v v out converter output voltage 0.807~13 v i out converter output current 0 ~ 2 a 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 4 ) apw 731 4 handling code tem perature range package code w 14 x package code az : tsot - 23 - 8 a temperature range i : - 40 to 85 o c handling code tr : tape & reel assembly material g : halogen and lead free device apw 731 4 a z : assembly material x - date code
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 - a u g . , 2 0 1 3 a p w 7 3 1 4 w w w . a n p e c . c o m . t w 3 symbol parameter range unit c out converter output capacitance 22 ~ 47 m f l1 inductance 4.7 ~ 10 m h t a ambient temperature - 40 ~ 85 o c t j junction temperature - 40 ~ 125 o c 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 ( c o n t . ) ( n o t e 3 ) note 3 : refer to the typical application circuit. 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 ap w7314 symbol parameter test conditions min typ max unit supply current i vin vin supply current v fb = 0.9v , sw=nc - 0.5 1 ma i vin_sd vin shutdown supply current v en =0v - - 10 m a vin under - voltage lockout vin under - voltage lockout threshold v in rising 3.7 3.9 4.1 v vin under - voltage lockout hysteresis - 0.6 - v reference voltage v ref reference voltage - 0.8 07 - v output voltage accuracy t j =25c, i out =10ma - 2 - +2 % i fb fb input current - 10 50 n a v vcc vcc regulator - 5 - v vcc load regulation i vcc =3ma - 3 - % oscillator and duty cycle f sw switching frequency 430 500 570 khz d amx maximum duty cycle - 93 - % minimum on - time - 60 - ns power mosfet high side mosfet resistance - 1 5 0 - m w low side mosfet resistance - 7 0 - m w high side switch leakage current v en =0v , v in =24v, v sw =0v - - 10 m a low side switch leakage current v en =0v , v in =24v, v sw =24v - - 10 m a soft - start, enable t ss soft start time - 1.5 - ms en rising threshold v oltage v in =4.5v ~ 24v 1.2 1.4 1.6 v en falling threshold hysteresis v in =4.5v ~ 24v - 0.2 - v en turn off delay - 8 - m s en input current v en =2v - 2 - m a refer to the typical application circuits. these specifications apply over v in =12v, v en =3v and t a =25c.
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 - a u g . , 2 0 1 3 a p w 7 3 1 4 w w w . a n p e c . c o m . t w 4 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 ( c o n t . ) ap w7314 symbol parameter test conditions min typ max unit protections i lim high side mosfet current - limit 3 4 5 a ovp rising threshold - 1 25 - %v ref ovp falling threshold - 105 - %v ref over - temperature protection (otp) t j rising - 150 - o c over - temperature hyteresis t j falling - 30 - o c refer to the typical application circuits. these specifications apply over v in =12v, v en =3v and t a =25c. p i n d e s c r i p t i o n pin no. name function 1 iset connect to a voltage supply through 2 resistor dividers to force the apw7314 into non - synchronous mode under light loads. pull iset pin to vcc to force the apw7314 into ccm. 2 vin power input. vin supplies the power to the control circuitry, gate driver. connecting a ceramic bypass capacitor and a suitably large capacitor between vin and gnd eliminates switching noise and voltage ripple on the input to the ic. 3 sw power switching output. sw is the source of the n - channel p ower mosfet to supply power to the output lc filter. 4 gnd signal and power ground. 5 bst high - side gate drive boost input. bs supplies the voltage to drive the high - side n - channel mosfet. at least 10nf capacitor should be connected from sw to bs to supp ly the high side switch. 6 en enable input. en is a digital input that turns the regulator on or off. en threshold is 1. 4 v with 0. 2 v hysteresis . pull up with 100k w resistor for automatic startup. 7 vcc bias supply. decouple with a 0.1 m f capacitor or higher is recommended. 8 fb output feedback input. the ic senses the feedback voltage via fb and regulates fb voltage at 0.807 v. connecting fb with a resistor - divider from the converter?s output to set the output voltage.
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 - a u g . , 2 0 1 3 a p w 7 3 1 4 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 s h u t d o w n c u r r e n t ( u a ) 0 2 4 6 8 10 12 shutdown current vs . input voltage 4 8 12 16 20 24 input voltage ( v ) input voltage ( v ) s u p p l y c u r r e n t ( m a ) supply current vs . input voltage 0 . 6 0 . 7 0 . 8 0 . 9 4 8 12 16 20 24 0 0 . 4 0 . 8 1 . 2 1 . 6 2 - 1 - 0 . 5 0 0 . 5 - 1 . 5 load regulation output current ( a ) o u t p u t v o l t a g e v a r i a t i o n ( % ) 4 8 12 16 20 24 0 0 . 1 0 . 2 0 . 3 - 0 . 1 line regulation input voltage ( v ) o u t p u t v o l t a g e v a r i a t i o n ( % ) 0 . 797 0 . 802 0 . 807 0 . 812 0 . 817 - 40 - 20 0 20 40 60 80 r e f e r e n c e v o l t a g e ( v ) reference voltage vs . junction temperature 100 junction temperature ( o c ) 120 140 0 . 01 0 . 1 1 10 60 70 75 80 85 90 95 e f f i c i e n c y ( % ) efficiency vs . load current 65 output current ( a ) f sw = 500 khz , v in = 12 v 100 vout = 5 v vout = 3 . 3 v vout = 1 . 2 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 - a u g . , 2 0 1 3 a p w 7 3 1 4 w w w . a n p e c . c o m . t w 6 o p e r a t i n g w a v e f o r m s refer to the typical application circuit. the test condition is v in =12v, t a = 25 o c unless otherwise specified. ch 1 : v in , 5 v / div ch 2 : v out , 2 v / div time : 2 ms / div power on 1 3 2 ch 3 : v lx , 10 v / div v in v out v lx ch 2 : v out , 2 v / div time : 2 ms / div ch 1 : v in , 5 v / div power off 1 3 2 v in v out ch 3 : v lx , 10 v / div v lx enable ch 1 : v en , 2 v / div ch 2 : v out , 2 v / div time : 2 ms / div ch 3 : v lx , 10 v / div v en v out 1 3 2 v lx shutdown ch 1 : v en , 2 v / div ch 2 : v out , 2 v / div time : 50 us / div ch 3 : v lx , 10 v / div v lx v out 1 3 2 v en
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 - a u g . , 2 0 1 3 a p w 7 3 1 4 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 refer to the typical application circuit. the test condition is v in =12v, t a = 25 o c unless otherwise specified. short - current recovery 1 2 v out i l ch 1 : v out , 2 v / div ch 2 : v lx , 10 v / div ch 3 : i l , 2 a / div time : 2 ms / div v lx 3 vout ripple 1 3 2 ch 1 : v out , 50 mv / div , ac ch 2 : v lx , 10 v / div ch 3 : i l , 2 a / div time : 2 us / div v out v lx i l load transient 1 3 2 ch 1 : v out , 100 mv / div , ac ch 2 : v lx , 10 v / div ch 3 : i out , 1 a / div time : 50 us / div v out v lx i out short - current entry 1 3 ch 1 : v out , 2 v / div ch 2 : v lx , 10 v / div ch 3 : i l , 2 a / div time : 2 ms / div 2 v out v lx i 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 - a u g . , 2 0 1 3 a p w 7 3 1 4 w w w . a n p e c . c o m . t w 8 b l o c k d i a g r a m vcc regulator oscillator sw vcc fb vin bst logic control vcc iset gnd soft - start v ref uvlo current limit comparator slope compensation ? rsen en comp icmp 6 v 1 m w
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 - a u g . , 2 0 1 3 a p w 7 3 1 4 w w w . a n p e c . c o m . t w 9 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 vin v cc iset en off on v in 12 v sw fb gnd apw 7314 v out 3 . 3 v / 2 a c out 47 m f c in 22 m f l 1 5 . 6 m h r 1 40 . 2 k r 2 13 k r 4 90 . 9 k r 5 1 0 k bst c 4 0 . 1 m f c 6 0 . 1 m f r 3 33 k
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 - a u g . , 2 0 1 3 a p w 7 3 1 4 w w w . a n p e c . c o m . t w 1 0 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 3 1 4 i s a c o n s t a n t f r e q u e n c y , s y n c h r o n o u s r e c - t i f i e r 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 u p p e r 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 . 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 t u r n o f f t h e u p p e r m o s f e t 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 d e c r e a s e i n v f b r e l a t i v e t o t h e 0 . 8 0 7 v r e f e r e n c e , w h i c h i n t u r n 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 . u n d e r v o l t a g e l o c k o u t ( u v l o ) a n u n d e r - v o l t a g e l o c k o u t f u n c t i o n p r e v e n t s t h e d e v i c e f r o m o p e r a t i n g i f t h e i n p u t v o l t a g e o n v i n i s l o w e r t h a n a p p r o x i - m a t e l y 3 . 9 v . t h e d e v i c e a u t o m a t i c a l l y e n t e r s t h e s h u t - d o w n m o d e i f t h e v o l t a g e o n v i n d r o p s b e l o w a p p r o x i - m a t e l y 3 . 9 v . t h i s u n d e r - v o l t a g e l o c k o u t f u n c t i o n i s i m p l e - m e n t e d i n o r d e r t o p r e v e n t t h e m a l f u n c t i o n i n g o f t h e c o n v e r t e r . enable/shutdown driving en to the ground places the apw7314 in shut- down mode. when in shutdown, the internal power mosfets turn off, all internal circuitry shuts down and the quiescent supply current reduces to 1 m a typical. o v e r - c u r r e n t - p r o t e c t i o n a n d h i c c u p t h e a p w 7 3 1 4 h a s a c y c l e - b y - c y c l e o v e r - c u r r e n t l i m i t w h e n t h e i n d u c t o r c u r r e n t p e a k v a l u e e x c e e d s t h e s e t c u r r e n t l i m i t t h r e s h o l d . m e a n w h i l e , t h e o u t p u t v o l t a g e d r o p s u n t i l f b i s b e l o w t h e u n d e r - v o l t a g e ( u v ) t h r e s h o l d b e l o w t h e r e f e r e n c e . o n c e u v i s t r i g g e r e d , t h e a p w 7 3 1 4 e n t e r s h i c - c u p m o d e t o p e r i o d i c a l l y r e s t a r t t h e p a r t . t h i s p r o t e c t i o n m o d e i s e s p e c i a l l y u s e f u l w h e n t h e o u t p u t i s d e a d - s h o r t e d t o g r o u n d . t h e a v e r a g e s h o r t c i r c u i t c u r r e n t i s g r e a t l y r e - d u c e d t o a l l e v i a t e t h e r m a l i s s u e s a n d t o p r o t e c t t h e r e g u l a t o r . t h e a p w 7 3 1 4 e x i t s t h e h i c c u p m o d e o n c e t h e o v e r - c u r r e n t c o n d i t i o n i s r e m o v e d . 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 3 1 4 . 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 b o t h p o w e r m o s f e t s , 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 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 3 0 o c . t h e o t p i s d e s i g n e d w i t h a 3 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 . o v e r - v o l t a g e p r o t e c t i o n ( o v p ) t h e o v e r - v o l t a g e f u n c t i o n m o n i t o r s t h e o u t p u t v o l t a g e b y f b p i n . o n c e t h e f b v o l t a g e e x c e e d s 1 2 0 % o f t h e r e f e r - e n c e v o l t a g e , t h e o v e r - v o l t a g e p r o t e c t i o n c o m p a r a t o r f o r c e s t h e l o w - s i d e m o s f e t o n . t h i s a c t i o n a c t i v e l y p u l l s d o w n t h e o u t p u t v o l t a g e t o p r e v e n t t h e e n d d e v i c e b e d a m a g e . a s s o o n a s t h e o u t p u t v o l t a g e i s b e l o w 1 0 5 % o f t h e r e f e r e n c e v o l t a g e , t h e l o w - s i d e m o s f e t o f f a n d t h e o v p c o m p a r a t o r i s d i s e n g a g e d . t h e c h i p r e s t o r e s i t s n o r m a l o p e r a t i o n . s o f t - s t a r t t h e a p w 7 3 1 4 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 ( 0 . 8 0 7 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 . t h e n , t h e v o l t a g e o n f b r e g u l a t e d a t r e f e r e n c e v o l t a g 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 - a u g . , 2 0 1 3 a p w 7 3 1 4 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 f r e q u e n c y f o l d b a c k t h e f o l d b a c k f r e q u e n c y i s c o n t r o l l e d b y t h e f b v o l t a g e . w h e n t h e o u t p u t i s s h o r t e n e d t o t h e g r o u n d , t h e f r e q u e n c y o f t h e o s c i l l a t o r w i l l b e r e d u c e d t o 0 . 2 5 x f s w . t h i s l o w e r f r e q u e n c y a l l o w s t h e i n d u c t o r c u r r e n t t o s a f e l y d i s c h a r g e , t h e r e b y p r e v e n t i n g c u r r e n t r u n a w a y . t h e o s c i l l a t o r ? s f r e - q u e n c y w i l l g r a d u a l l y i n c r e a s e t o i t s d e s i g n e d r a t e w h e n t h e f e e d b a c k v o l t g a e o n f b a g a i n a p p r o a c h e s 0 . 8 0 7 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 - a u g . , 2 0 1 3 a p w 7 3 1 4 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 i n d u c t o r s e l e c t i o n t o a v o i d 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 o u t 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 . l ) max ( out ) max ( l l sw in out out i 2 1 i i i f v v 1 v l d + = d ? ? ? ? ? - 3 b e c a u s e b u c k c o n v e r t e r s h a v e a p u l s a t i n g i n p u t c u r r e n t , a l o w e s r i n p u t c a p a c i t o r i s r e q u i r e d . t h i s r e s u l t s i n t h e b e s t i n p u t v o l t a g e f i l t e r i n g , m i n i m i z i n g t h e i n t e r f e r e n c e w i t h o t h e r c i r c u i t s c a u s e d b y h i g h i n p u t v o l t a g e s p i k e s . a l s o , t h e i n p u t c a p a c i t o r m u s t b e s u f f i c i e n t l y l a r g e t o s t a - b i l i z e t h e i n p u t v o l t a g e d u r i n g h e a v y l o a d t r a n s i e n t 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 , u s u a l l y a 2 2 m f i n p u t c a p a c i t o r i s s u f f i c i e n t . i t c a n b e i n c r e a s e d w i t h o u t a n y l i m i t f o r b e t t e r i n p u t - v o l t a g e f i l t e r i n g . c e r a m i c c a p a c i t o r s s h o w b e t t e r p e r f o r m a n c e b e c a u s e o f t h e l o w e s r v a l u e , a n d t h e y a r e l e s s s e n s i t i v e a g a i n s t v o l t a g e t r a n s i e n t s a n d s p i k e s c o m - p a r e d t o t a n t a l u m c a p a c i t o r s . p l a c e t h e i n p u t c a p a c i t o r a s c l o s e a s p o s s i b l e t o t h e i n p u t a n d g n d p i n o f t h e d e v i c e f o r b e t t e r p e r f o r m a n c e . for high efficiencies, the inductor should have a low dc resistance to minimize conduction losses. especially at high-switching frequencies, the core material has a higher impact on efficiency. when using small chip inductors, the efficiency is reduced mainly due to higher inductor core losses. this needs to be considered when selecting the appropriate inductor. the inductor value determines the inductor ripple current. the larger the in- ductor value, the smaller the inductor ripple current and the lower the conduction losses of the converter. conversely, larger inductor values cause a slower load transient response. a reasonable starting point for set- ting ripple current, d i l , is 40% of maximum output current. the recommended inductor value can be calculated as below: i n t h e a d j u s t a b l e v e r s i o n , 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 , a l l o w i n g 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 ? . 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 1 807 . 0 2 r 1 r 1 v v ref out o u t p u t v o l t a g e s e t t i n g o u t p u t c a p a c i t o r s e l e c t i o n the current-mode control scheme of the apw7314 al- lows the use of tiny ceramic capacitors. the higher ca- pacitor value provides the good load transients response. ceramic capacitors with low esr values have the lowest output voltage ripple and are recommended. if required, tantalum capacitors may be used as well. the output ripple is the sum of the voltages across the esr and the ideal output capacitor. ? ? ? ? ? + ? ? ? ? ? - @ d out sw sw in out out out c f 8 1 esr l f v v 1 v v 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 , c h o o s e t h e x 5 r o r x 7 r d i e l e c t r i c f o r m u l a t i o n s . t h e s e d i e l e c t r i c s h a v e t h e b e s t 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 o f a l l t h e c e r a m i c s f o r a g i v e n v a l u e a n d s i z 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 - a u g . , 2 0 1 3 a p w 7 3 1 4 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 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 o a v o i d s 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 , c h o o s e t h e x 5 r o r x 7 r d i e l e c t r i c f o r m u l a t i o n s . t h e s e d i e l e c t r i c s h a v e t h e b e s t 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 o f a l l t h e c e r a m i c s f o r a g i v e n v a l u e a n d s i z e . 3 . t h e o u t 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 c l o s e d t o c o n - v e r t e r v o u t a n d g n d . 4 . 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 . 5 . 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 . l a y o u t c o n s i d e r a t i o n for all switching power supplies, the layout is an impor- tant step in the design; especially at high peak currents and switching frequencies. if the layout is not carefully done, the regulator might show noise problems and duty cycle jitter. 1. the input capacitor should be placed close to the vin and gnd. connecting the capacitor and vin/gnd with short and wide trace without any via holes for good input voltage filtering. the distance between vin/gnd to ca- pacitor less than 2mm respectively is recommended. 2. to minimize copper trace connections that can inject noise into the system, the inductor should be placed as close as possible to the sw pin to minimize the noise coupling into other circuits. v in v out i l q 2 sw i out c in c out i in esr q 1 i q 1 i lim i l i peak i out i q 1 i l 0 . 057 0 . 0 1 7 0 . 102 0 . 0 2 6 r e c o m m e n d e d m i n i m u m f o o t p r i n t t s o t - 2 3 - 8 a
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 - a u g . , 2 0 1 3 a p w 7 3 1 4 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 - 8 a 0 . 016 0 . 008 0 . 024 0 . 004 0 . 039 max . 0 . 10 0 e e l e 1 0 o d c b 0 . 08 0 . 22 0 . 004 0 . 40 0 . 20 0 . 012 0 . 009 0 . 003 millimeters min . s y m b o l a 1 a 2 a 0 . 01 0 . 70 tsot - 23 - 8 a max . 0 . 10 1 . 00 min . 0 . 000 0 . 028 inches 2 . 60 0 . 102 1 . 95 bsc 0 . 077 bsc 3 . 00 0 . 118 2 . 70 310 0 . 106 0 . 122 0 . 65 bsc 0 . 026 bsc 1 . 40 1 . 80 0 . 055 0 . 071 d e 1 e e b e 1 c see view a view a l 0 . 2 5 gauge plane seating plane x a 2 a a 1 nx aaa c e 1 aaa 0 . 70 0 . 028 0 . 90 0 . 30 0 . 60 8 o 0 . 035 0 o 8 o
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 - a u g . , 2 0 1 3 a p w 7 3 1 4 w w w . a n p e c . c o m . t w 1 5 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 - 8a 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 (mm) d e v i c e s p e r u n i t 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 package type unit quantity tsot - 23 - 8a 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 - a u g . , 2 0 1 3 a p w 7 3 1 4 w w w . a n p e c . c o m . t w 1 6 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 s o t - 2 3 - 8 a c l a s s i f i c a t i o n p r o f i l e aaax aaax aaax aaax aaax aaax user direction of feed aaax
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 - a u g . , 2 0 1 3 a p w 7 3 1 4 w w w . a n p e c . c o m . t w 1 7 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 @ tj=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 - a u g . , 2 0 1 3 a p w 7 3 1 4 w w w . a n p e c . c o m . t w 1 8 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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