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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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 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 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 f o r 2 t o 6 w h i t e l e d s t h e a p w 7 2 0 8 i s a c u r r e n t - m o d e a n d f i x e d f r e q u e n c y b o o s t c o n v e r t e r w i t h a n i n t e g r a t e d n - f e t t o d r i v e u p t o 6 w h i t e l e d s i n s e r i e s . f e a t u r e s wide input voltage from 2.5v to 6v 104mv reference voltage fixed 1mhz switching frequency high efficiency up to 88% 100hz to 100khz pwm brightness control fre- quency open-led protection under-voltage lockout protection over-temperature protection <1 m a quiescent current during shutdown sot-23-6 and tsot-23-6 packages 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 white led display backlighting cell phone and smart phone pda, pmp, and mp3 digital camera 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 t h e s e r i e s c o n n e c t i o n a l l o w s t h e l e d c u r r e n t t o b e i d e n - t i c a l f o r u n i f o r m b r i g h t n e s s . i t s l o w o n - r e s i s t a n c e o f n - f e t a n d f e e d b a c k v o l t a g e r e d u c e s p o w e r l o s s a n d a c h i e v e s h i g h e f f i c i e n c y . f a s t 1 m h z c u r r e n t - m o d e p w m o p e r a t i o n i s a v a i l a b l e f o r i n p u t a n d o u t p u t c a p a c i t o r s a n d a s m a l l i n d u c t o r w h i l e m i n i m i z i n g r i p p l e o n t h e i n p u t s u p p l y . t h e o v p p i 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 a n d s t o p s s w i t c h i n g i f e x c e e d s t h e o v e r - v o l t a g e t h r e s h o l d . a n i n t e r - n a l s o f t - s t a r t c i r c u i t e l i m i n a t e s t h e i n r u s h c u r r e n t d u r i n g s t a r t - u p . t h e a p w 7 2 0 8 a l s o i n t e g r a t e s u n d e r - v o l t a g e l o c k o u t , 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 a n d c u r r e n t l i m i t c i r c u i t s . t h e a p w 7 2 0 8 i s a v a i l a b l e i n s o t - 2 3 - 6 a n d t s o t - 2 3 - 6 p a c k a g e s . gnd vin v out en lx fb ovp 4 6 5 3 2 1 l1 22 m h c2 1 m f c1 2.2 m f r1 5.1 w v in up to 6 wleds off on 4 en 6 vin gnd 2 5 ovp fb 3 lx 1 sot-23-6 / tsot-23-6 (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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 2 symbol parameter rating unit v in vin supply voltage (vin to gnd) - 0.3 ~ 7 v fb, en to gnd voltage - 0.3 ~ v in v v lx lx to gnd voltage - 0.3 ~ 34 v v ovp ovp to gnd voltage - 0.3 ~ 32 v t j maximum junction temperature 150 c t stg storage temperatur e - 65 ~ 150 c t s dr 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 q ja junction to ambient t hermal r esistance (note 2) sot - 23 - 6 t - sot - 23 - 6 250 220 c /w 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 2.5 ~ 6 v v out converter output voltage up to 24 v c in input capacitor 2.2 or higher m f c out output capacitor 0.47 or higher m f l1 inductor 6.8 ~ 22 m h t a ambient temperature - 40 ~ 85 c t j juncti on temperature - 40 ~ 125 c 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 : a b s o l u t e m a x i m u m r a t i n g s a r e t h o s e v a l u e s b e y o n d w h i c h t h e l i f e o f a d e v i c e m a y b e i m p a i r 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 . note 2: q ja is measured with the component mounted on a high effective thermal conductivity test board in free air. the exposed pad of package is soldered directly on the pcb. n o t e 3 : r e f e r t o t h e a p p l i c a t i o n c i r c u i t f o r f u r t h e r i n f o r m a t i o n . APW7208 c/ct : x - date code package code c : sot-23-6 ct : tsot-23-6 operating ambient temperature range i : -40 to 85 o c handling code tr : tape & reel assembly material g : halogen and lead free device w08x APW7208 handling code temperature range package code assembly material
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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 3 apw7 208 symbol parameter test conditions min. typ. max. unit supply voltage and current v in input voltage range t a = - 40 ~ 85 c , t j = - 40 ~ 125 c 2.5 - 6 v i dd1 v fb = 0.3v, no switching 70 100 130 a i dd2 fb = gnd, swit ching - 1 2 m a i sd input dc bias current en = gnd - - 1 a under - voltage lockout uvlo threshold voltage v in rising 2.2 2.3 2.48 v uvlo hysteresis voltage 50 100 150 mv reference and output voltages v ref regulated feedback voltage t a = 25 c 101 104 107 mv i fb fb inpu t current - 50 - 50 n a internal power switch f sw switching frequency fb= gnd 0.8 1.0 1.2 mhz r on power switch on resistance - 0.6 1.2 w i lim power switch current limit - 1.2 - a lx leakage current v en =0v, v lx =0v or 5v, v i n = 5v - 1 - 1 a d max lx ma ximum duty cycle 92 95 98 % output over - voltage protection v ovp over voltage threshold 26 28 30 v ovp hysteresis 1 - 4 v ovp leakage current v ovp =24v - - 45 a enable and shutdown v ten en voltage threshold v e n rising 0.4 0.7 1 v en voltage hy steresis 0.05 0.1 0.15 v i len en leakage current v en = 0~ 5v, v i n = 5v - 1 - 1 a over - temperature protection t otp over - temperature protection t j rising - 150 - c over - temperature protection hysteresis - 40 - c 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 ( r e f e r t o f i g u r e 1 i n 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 s ? . t h e s e s p e c i f i c a t i o n s a p p l y o v e r v i n = 3 . 6 v , u n l e s s o t h e r w i s e n o t e d . t a = 2 5 c . )
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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 4 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 efficiency vs. wled current efficiency vs. wled current wled current vs. pwm duty cycle switching frequency vs. supply voltage switch on resistance vs. supply voltage wled current vs. supply voltage ( r e f e r t o f i g u r e 1 i n t h e s e c t i o 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 ? , v i n = 3 . 6 v , t a = 2 5 o c , 6 w l e d s u n l e s s o t h e r w i s e s p e c i f i e d ) s w i t c h i n g f r e q u e n c y , f s w ( m h z ) supply voltage, v in (v) 2.5 3 3.5 4 4.5 5 5.5 6 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 w l e d c u r r e n t , i l e d ( m a ) supply voltage, v in (v) 19.0 19.2 19.4 19.6 19.8 20.0 20.2 20.4 20.6 20.8 21.0 2.5 3 3.5 4 4.5 5 5.5 6 s w i t c h o n r e s i s t a n c e , r o n ( [ ) supply voltage, v in (v) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 2.5 3 3.5 4 4.5 5 5.5 6 e f f i c i e n c y ( h ) wled current, i led (ma) 0 5 10 15 20 25 30 50 55 60 65 70 75 80 85 90 95 v in =3.3v v in =3.6v v in =4.2v v in =5v 6 wleds 19.3v@20ma h= p out /p in @ e f f i c i e n c y ( h ) 4 wleds 13v@20ma h= p out /p in v in =3.3v v in =3.6v v in =4.2v v in =5v 0 5 10 15 20 25 30 50 55 60 65 70 75 80 85 90 95 @ wled current, i led (ma) w l e d c u r r e n t , i l e d ( m a ) pwm duty cycle (%) 0 20 40 60 80 100 0 2 4 6 8 10 12 14 16 18 20 100hz 100khz 1khz
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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 5 o p e r a t i n g w a v e f o r m s ( r e f e r t o t h e a p p l i c a t i o n c i r c u i t i n t h e s e c t i o 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 ? , v i n = 3 . 6 v , t a = 2 5 o c , 6 w l e d s u n l e s s o t h e r w i s e s p e c i f i e d ) start-up ch1: v en , 2v/div, dc ch2: v in , 2v/div, dc ch3: v out , 10v/div, dc ch4: i in , 0.1a/div, dc time: 1ms/div 2 1 3 4 v out i in , 0.1a/div v in v en 6wleds, l=22 h, v in =3.6v, i led =20ma start-up ch1: v en , 2v/div, dc ch2: v in , 2v/div, dc ch3: v out , 10v/div, dc ch4: i in , 0.1a/div, dc time: 1ms/div 2 1 3 4 v out i in , 0.1a/div v in v en 4wleds, l=22 h, v in =3.6v, i led =20ma open-led protection ch1: v out , 10v/div, dc time: 20ms/div 1 v out , 10v/div normal operating waveform 1 2 3 v lx , 20v/div, dc v out , 50mv/div, ac i l , 0.1a/div 6wleds, l=22 h, v in =3.6v, i led =20ma ch1: v lx , 20v/div, dc ch2: v out , 50mv/div, ac ch3: i l , 0.1a/div, dc time: 1 s/div
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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 6 p i n d e s c r i p t i o n pin no. name function 1 lx switch pin . connect this pin to inductor/diode here. 2 gnd power and signal ground pin. 3 fb feedback pin . reference voltage is 104mv. connect this pin to cathode of the lowest led and resistor (r1). calculate resistor v alue according to r1=104mv/i led . 4 en enable control i nput. forcing this pin above 1. 0 v enables the device, or f orcing this pin below 0. 4 v to shut it down. in shutdown, all f unctions are disabled to decrease the supply current below 1 m a. do not leave this pin floating. 5 ovp over - voltage protection pin. ovp is connected to the output capacitor of the converter. 6 vin main s upply pin. must be closely decoupled to the gnd with a 2.2 m f or greater ceramic capacitor. b l o c k d i a g r a m uvlo oscillator control logic s vin en fb gnd lx ovp over- temperature protection v ref 104mv eamp comp i cmp slope compensation gate driver current sense amplifier error amplifier current limit soft- start
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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 7 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 figure 3. brightness control using a filtered pwm signal figure 4. circuit for driving 27 wleds gnd vin v out en lx fb ovp 4 6 5 3 2 1 l1 22 h c2 1 f c1 2.2 f r1 5.1 w r2 3.2k r3 100k c3 0.1 f r4 10k v in up to 6 wleds off on APW7208 max , led ref min , led min , adj min , led ref max , led max , adj max , adj min , led min , adj max , led ref i v i v i v i v v 3 r i v 3 r i v 2 r - - + - - + = max , led min , adj ref i v 3 r 2 r 3 r 2 r 1 v 1 r - ? ? ? ? + = v adj pwm brightness control duty=100%, led off duty=0%, i led =20ma 3.3v 0v gnd vin v out en lx fb ovp 4 6 5 3 2 1 l1 10 h c2 10 f c1 10 f r1 1.1 w v in 4.5v~6v 9 strings total off on APW7208 r2 1.1 w figure 1. typical 6 wleds application gnd vin v out en lx fb ovp 4 6 5 3 2 1 l1 22 h c2 1 f c1 2.2 f r1 5.1 w v in up to 6 wleds off on APW7208 figure 2. brightness control using a pwm signal applies to en gnd vin v out en lx fb ovp 4 6 5 3 2 1 l1 22 h c2 1 f c1 2.2 f r1 5.1 w v in up to 6 wleds APW7208 100hz~100khz duty=100%, i led =20ma duty=0%, led off
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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 8 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 0 8 i s a c o n s t a n t f r e q u e n c y 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 . d u r i n g 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 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 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 1 0 4 m 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 . v i n u n d e r - v o l t a g e l o c k o u t ( u v l o ) 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 ( 2 . 3 v r i s i n g , t y p i c a l ) 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 0 8 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 n - c h a n n e l m o s f e t c u r r e n t 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 , c o n n e c t e d t o o n e o f t h e i n v e r t i n g i n p u t s , r a i s e u p t o r e p l a c e t h e o u t p u t v o l t a g e o f e r r o r a m - p l i f i e r 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 v c o m p . 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 0 8 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 i n g 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 0 8 f r o m d a m a g e s 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 ) the over-temperature circuit limits the junction tempera- ture of the APW7208. when the junction temperature ex- ceeds 150 o c , a thermal sensor turns off the power mosfet, allowing the devices to cool. the thermal sen- sor allows the converters to start a soft-start process and to regulate the output voltage again after the junction tem- perature cools by 40 o c . the otp is designed with a 40 o c hysteresis to lower the average junction temperature (t j ) during continuous thermal overload conditions, in- creasing the lifetime of the device. 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 0 8 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 n e 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 . o p e n - l e d p r o t e c t i o n i n d r i v i n g l e d a p p l i c a t i o n s , t h e f e e d b a c k v o l t a g e o n t h e f b p i n f a l l s d o w n i f o n e o f t h e l e d s , i n s e r i e s , i s f a i l e d . m e a n w h i l e , t h e c o n v e r t e r u n c e a s i n g l y b o o s t s t h e o u t p u t v o l t a g e l i k e a o p e n - l o o p o p e r a t i o n . t h e r e f o r e , a n o v e r - v o l t a g e p r o t e c t i o n ( o v p ) , m o n i t o r i n g t h e o u t p u t v o l t a g e v i a o v p p i n , i s i n t e g r a t e d i n t o t h e c h i p t o p r e v e n t t h e l x a n d t h e o u t p u t v o l t a g e s f r o m e x c e e d i n g t h e i r m a x i m u m v o l t a g e r a t i n g s . w h e n t h e v o l t a g e o n t h e o v p p i n r i s e s a b o v e t h e o v p t h r e s h o l d ( 2 8 v t y p i c a l ) , t h e c o n v e r t e r s t o p s s w i t c h i n g a n d p r e v e n t s t h e o u t p u t v o l t a g e f r o m r i s i n g . t h e c o n v e r t e r c a n w o r k a g a i n w h e n t h e f a l l i n g o v p v o l t - a g e f a l l s b e l o w t h e o v p v o l t a g e t h r e s h o l d . this pin also could be used as a digital input allowing brightness control using a pwm signal from 100hz to 100khz. the 0% duty cycle of pwm signal corresponds to zero leds current and 100% corresponds to full one. seggestion dimming duty range is from 7% to 100%.
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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 9 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 e 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 0 8 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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 1 0 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 . d i o d e s e l e c t i o n t o a c h i e v 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 . s e t t i n g t h e l e d c u r r e n t i n f i g u r e 1 , t h e c o n v e r t e r r e g u l a t e s t h e v o l t a g e o n t h e f b p i n , c o n n e c t e d w i t h t h e c a t h o d o f t h e l o w e s t l e d a n d t h e c u r r e n t - s e n s e r e s i s t o r r 1 , a t 1 0 4 m v ( t y p i c a l ) . t h e r e f o r e , t h e c u r r e n t ( i l e d ) , f l o w i n g v i a t h e l e d s a n d t h e r 1 , i s c a l - c u l a t e d b y t h e f o l l o w i n g e q u a t i o n : i l e d = 1 0 4 m v / r 1 recommended inductor selection designator manufacturer part number i nductance (h) max dcr ( ohm ) saturation current (a) dimensions l x w x h (mm 3 ) l1 gotrend gtsd - 32 - 220 22 0.592 0.52 3.85 x 3.85 x 1.8 recommended capacitor selection designator manufactu rer part number capacitance ( f) tc code rated voltage (v) case size c1 murata grm188 c70j225ke20 2.2 x7s 6.3 0603 c2 murata grm21br71h105ka12 1.0 x7r 50 0805 recommended diode selection designator manufacturer part number maximum average forward rectifi ed current ( a) maximum repetitive peak reverse voltage (v) case size d1 zowie mscd104 1.0 40 0805 l a y o u t c o n s i d e r a t i o n 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 . c o n n e c t i n g t h e c a p a c i t o r w i t h v i n a n d g n d p i n s b y s h o r t a n d w i d e t r a c k s w i t h o u t u s i n g a n y v i a s f o r f i l t e r i n g a n d m i n i m i z i n g t h e i n p u t v o l t a g e r i p p l e . 2 . 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 l e n g t h o f t h e c o p p e r t r a c k s a s w e l l a s 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 k 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 . to anode of wleds from cathod of wleds r 1 r 4 r 3 r 2 c 3 via to ovp via to gnd l1 c1 via to v out d1 v adj v en v in lx refer to fig. 3 c 2 optimized APW7208 layout v out
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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 1 1 p a c k a g e i n f o r m a t i o n s o t - 2 3 - 6 note : 1. follow jedec to-178 ab. 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. e d e 1 b e1 e see view a c a a 2 a 1 q l view a 0 . 2 5 gauge plane seating plane 0 8 0 8 0.020 0.009 0.006 0.024 0.051 0.057 max. 0.30 l q e e e1 e1 d c b 0.08 0.30 0.012 0.60 0.95 bsc 1.90 bsc 0.50 0.22 0.075 bsc 0.037 bsc 0.012 0.003 millimeters min. s y m b o l a1 a2 a 0.00 0.90 sot-23-6 max. 1.30 0.15 1.45 min. 0.000 0.035 inches 1.40 2.60 3.00 1.80 2.70 3.10 0.118 0.071 0.122 0.102 0.055 0.106
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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 1 2 p a c k a g e i n f o r m a t i o n t s o t - 2 3 - 6 c see view a d e e1 b e 1 e a a 2 a 1 view a l 0 . 2 5 seating plane gauge plane note : 1. followed from jedec to-178 ab. 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. 0.020 0.008 0.002 0.024 0.030 0.031 max. 0.30 l 0 0 o c e e e1 e1 d c b 0.08 0.30 0.012 0.60 8 o c 0 o c 8 o c 0.95 bsc 1.90 bsc 0.50 0.20 0.075 bsc 0.037 bsc 0.012 0.003 millimeters min. s y m b o l a1 a2 a 0.03 0.70 tsot-23-6 max. 0.75 0.05 0.80 min. 0.001 0.028 inches 2.70 3.10 0.106 0.122 2.60 3.00 0.102 0.118 1.40 1.80 0.055 0.071 0.75 0.030
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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 1 3 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 sot - 23 - 6 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 - 0.4 0 3.20 ? 0.20 3.10 ? 0.20 1.50 ? 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 ? 0.30 1.75 ? 0.10 3.5 ? 0.05 p 0 p1 p 2 d 0 d1 t a 0 b 0 k 0 t sot - 23 - 6 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 1.50 ? 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 sot - 23 - 6 tape & reel 3000 tsot - 23 - 6 tape & reel 3000 h t1 a d a e 1 a b w f t p0 od0 b a0 p2 k0 b 0 section b-b section a-a od1 p1
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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 1 4 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 s o t - 2 3 - 6 / t s o t - 2 3 - 6 c l a s s i f i c a t i o n p r o f i l e user direction of feed aaax aaax aaax aaax aaax aaax 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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 1 5 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 . 6 - a u g . , 2 0 1 1 a p w 7 2 0 8 w w w . a n p e c . c o m . t w 1 6 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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