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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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 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 . d u a l 1 . 5 m h z , 1 a s y n c h r o n o u s s t e p - d o w n 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 a p p l i c a t i o n s t v t u n e r / b o x p o r t a b l e i n s t r u m e n t t h e a p w 7 1 7 6 c o n s i s t s o f t w o i n d e p e n d e n t 1 . 5 m h z 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 , a n d p w m s t e p - d o w n c o n v e r t e r s . e a c h c o n v e r t e r i n t e g r a t e s a m a i n s w i t c h w i t h a s y n c h r o n o u s r e c t i f i e r f o r h i g h e f f i c i e n c y w i t h o u t a n e x - t e r n a l s c h o t t k y d i o d e . t h e a p w 7 1 7 6 i s i d e a l f o r p o w e r i n g p o r t a b l e e q u i p m e n t t h a t r u n s f r o m a s i n g l e c e l l l i t h i u m - i o n ( l i + ) b a t t e r y . e a c h c o n v e r t e r c a n s u p p l y 1 a o f l o a d c u r r e n t f r o m a 2 . 7 v t o 5 . 5 v i n p u t v o l t a g e . t h e o u t p u t v o l t - a g e c a n b e r e g u l a t e d a s l o w a s 0 . 6 v . t h e a p w 7 1 7 6 c a n a l s o r u n a t 1 0 0 % d u t y c y c l e f o r l o w d r o p o u t a p p l i c a t i o n s . 1 a o u t p u t c u r r e n t o n e a c h c h a n n e l 2 . 7 v t o 5 . 5 v i n p u t v o l t a g e r a n g e 1 . 5 m h z c o n s t a n t f r e q u e n c y o p e r a t i o n l o w d r o p o u t o p e r a t i o n a t 1 0 0 % d u t y c y c l e s y n c h r o n o u s t o p o l o g y 0.6v low reference voltage c u r r e n t m o d e o p e r a t i o n 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 over-current protection u p t o 9 4 % e f f i c i e n c y i n t e r n a l l y c o m p e n s a t e d l e a d f r e e a n d g r e e n d e v i c e s a v a i l a b l e ( r o h s c o m p l i a n t ) p i n c o n f i g u r a t i o n 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 note: anpec lead-free products contain molding compounds/die attach materials and 100% matte tin plate termination finish; which are fully compliant with rohs. anpec lead-free products meet or exceed the lead-free requirements of ipc/jedec j-std-020d for msl classification at lead-free peak reflow temperature. anpec defines ?green? to mean lead-free (rohs compliant) and halogen free (br or cl does not exceed 900ppm by weight in homogeneous material and total of br and cl does not exceed 1500ppm by weight). en1 sw1 gnd1 in1 fb2 en2 sw2 gnd2 in2 fb1 tdfn3x3-10 (top view) exposed pad on backside APW7176 7 8 5 4 3 2 1 9 6 10 APW7176 package code qb : tdfn3x3-10 temperature range i : -40 to 85 o c handling code tr : tape & reel assembly material g : halogen and lead free device handling code temperature range package code assembly material APW7176 qb: apw 7176 xxxxx xxxxx - 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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 w w w . a n p e c . c o m . t w 2 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 in1/in2 input supply voltage (in1/in2 to gnd1/gnd2) - 0.3 ~ 6 v v fb1/fb2 voltage on fb1 and fb2 (fb1/fb2 to gnd1/gnd2) - 0.3 ~ v in1/in2 +0.3 v v en1/en2 voltage on en1 and en2 (en1/en2 to gnd1/gnd2) - 0.3 ~ v in1/in2 +0.3 v v sw1/ sw2 voltage on sw1 and sw2 (sw1/sw2 to gnd1/gnd2) - 0.3 ~ v in1/in2 +0.3 v i sw_peak peak sw current 1.8 a p d maximum power dissipation ( t a =25 o c) 2 w t j maximum j unction temperature 150 c t stg storage t emperature range - 65 ~ 150 c t sdr maximum lead s ol dering temperature, 10 seconds 260 c symbol parameter typical value unit q ja junction - to - ambient resistance in f ree a ir (note 2 ) tdfn3x3 - 10 50 q j c junction - to - case resistance in f ree a ir tdfn3x3 - 10 12 c/w t h e r m a l c h a r a c t e r i s t i c s note 2: q j a i s m e a s u r e d o n w i t h t h e d e v i c e m o u n t e d t h e p c b w i t h t o p - l a y e r p a d o f a p p r o x i m a t e 1 ? s q u a r e o f 1 o z c o p p 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 symbol parameter range unit v in1/in2 input supply voltage (in1/in2 to gnd1/gnd2) 2.7 ~ 5.5 v r2/r4 feedback resistance (note 3) ~ 300 k w i out output current 0 ~ 1 a t a operating ambient temperature - 40 ~ 85 c t j operating junction t emperature - 40 ~ 125 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 apw71 76 symbol parameter test conditions min. typ. max. unit v in1/in2 each converter input voltage range 2.7 - 5.5 v i fb1/fb2 fb1/fb2 input current v fb1/fb2 =0.6v - 30 - 30 na v ref 1/re f 2 each converter r eference voltage i out =0ma~ 1 a 0.588 0.6 0.612 v d v ref 1/ ref 2 each converter reference v oltage line r egulation - 40 o c t a 85 o c - 0.04 - %/v i pk each converter peak inductor current v in1/in2 =3 .3 v, v fb =0.5v or v out =90%, duty cycle < 35% 1.4 1.6 - a t h e d e n o t e s t h e s p e c i f i c a t i o n s t h a t a p p l y o v e r v i n = 3 . 6 v a n d t a = 2 5 c , u n l e s s o t h e r w i s e s p e c i f i c a t i o n s . 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 . 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 .
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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 w w w . a n p e c . c o m . t w 3 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 . ) apw71 76 symbol parameter test conditions min. typ. max. unit each converter load regulation i out =10ma~ 1 a - 0.5 - % i dd each converter quiescent current v fb = 0.7 v - 30 50 m a i sd each converter quiescent current in shutdown v en1/en2 =0v, v in =4.2v - - 1 m a f osc each converter oscillator frequency v fb =0.6v 1.2 1.5 1.8 mhz f osc_ffb each converter frequency foldback v fb =0v - 210 - khz r ds - p each converter on resistance of pmosfet i sw =100ma - 0. 28 - w r ds - n each converter on resistance of nmosfet i sw = - 100ma - 0.25 - w v en1/en2 each converter enable threshold 0. 4 - 1 v t otp thermal shutdown threshold - 150 - o c thermal shutdown hysteresis - 50 - o c t h e d e n o t e s t h e s p e c i f i c a t i o n s t h a t a p p l y o v e r v i n = 3 . 6 v a n d t a = 2 5 c , u n l e s s o t h e r w i s e s p e c i f i c a t i o n s .
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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 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 ( 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 , v o u t = 1 . 8 v , t a = 2 5 o c u n l e s s o t h e r w i s e s p e c i f i e d ) 20 30 40 50 60 70 80 90 100 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 efficiency vs. load current e f f i c i e n c y ( % ) load current, i out (a) v out = 1.8v l = 2.2 h c out = 10 f v in =5v v in =3.3v efficiency vs. load current e f f i c i e n c y ( % ) load current, i out (a) 20 30 40 50 60 70 80 90 100 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 v out = 1.2v l = 2.2 h c out = 10 f v in =5v v in =3.3v o n r e s i s t a n c e ( w ) supply voltage, v in (v) 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 2 2.5 3 3.5 4 4.5 5 5.5 6 supply voltage vs. on resistance r n-fet r p-fet q u i e s c e n t c u r r e n t , i d d ( a ) supply voltage vs. quiescent current supply voltage, v in (v) 0 5 10 15 20 25 30 35 40 2 2.5 3 3.5 4 4.5 5 5.5 6 r e f e r e n c e v o l t a g e , v r e f ( v ) supply voltage v.s. reference voltage supply voltage, v in (v) 0.55 0.56 0.57 0.58 0.59 0.6 0.61 0.62 0.63 0.64 0.65 2 2.5 3 3.5 4 4.5 5 5.5 6
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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 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 , v o u t = 1 . 8 v , t a = 2 5 o c u n l e s s o t h e r w i s e s p e c i f i e d ) load transient response 300ma 2 1 v out ,100mv/div, ac i out , 0.5a/div, dc 1a l=2.2 h, v in =5v, v out =1.8v, c out =10 f time: 100 s/div normal operation 2 1 v out, 200mv/div,ac v in, 0.5v/div 1.5v 2.5v i out = 100ma time: 500ns/div 3 i l , 500mv/div, dc v out ,20mv/div, ac v sw ,2v/div, dc l=2.2 h, v in =5v, v out =1.2v, c out =10 f 3 1 2 soft start v out ,1v/div, dc i in , 200ma/div l=2.2 h, v in =5v, c out =10 f time: 100 s/div 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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 w w w . a n p e c . c o m . t w 6 pin no. name function 1 en1 channel 1 enable control input. drive en1 above 1 v to turn on the channel 1. drive en1 below 0. 4 v to turn it off . in shutdown situation, all functions are disabled to decrease the supply current below 1 m a. don ? t left this pin floating . 2 fb1 channel 1 feedback input. connect fb1 to the center point of the external resistor divider. the feedback voltage is 0.6v. 3 in2 channel 2 supply input. bypass to the gnd 2 with a 4.7 m f or greater ceramic capacitor. 4 gnd2 ground 2. conne cted the exposed pad to the gnd2. 5 sw2 channel 2 power switch output. inductor connection to drains of the internal pmosfet and nmosfet switches. 6 en2 channel 2 enable control input. drive en 2 above 1 v to turn on the channel 2. drive en2 below 0. 4 v to turn it off . in shutdown situation, all functions are disabled to decrease the supply current below 1 m a. don ? t left this pin floating . 7 fb2 channel 2 feedback input. connect fb2 to the center point of the external resistor divider. the feedback voltage is 0.6v. 8 in1 channel 1 supply input. bypass to the gnd 1 with a 4.7 m f or greater ceramic capacitor. 9 gnd1 ground 1. connected the exposed pad to the gnd1. 10 sw1 channel 1 power switch output. inductor connection to drains of the internal pmosfet and nmosfet switches. exposed pad nc no internal connection. connecting this pad to gnd1 and gnd2. p i n d e s c r i p t i o n b l o c k d i a g r a m diagram represents 1/2 of the APW7176 oscillator logic control sw1/sw2 over- temperature protection v ref 0.6v eamp comp i cmp soft- start current limit in1/in2 shutdown control ? fb1/fb2 en1/en2 gnd1/gnd2 gate driver
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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 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 en1 sw1 fb1 en2 sw2 fb2 in1 in2 gnd1 gnd2 APW7176 c in1 4.7 m f r5 100k w v in1/in2 off on off on c in2 4.7 m f r6 100k w v out1 1.2v 1a v out2 3.3v 1a c out1 10 m f c out2 10 m f r1 150k w r4 47k w r3 300k w r2 150k w l1 2.2 m h l2 2.2 m h 1 3 6 7 5 4 8 2 10 9 10pf 10pf
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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 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 t h e a p w 7 1 7 6 h a s d u a l i n d e p e n d e n t 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 p w m s t e p - d o w n c o n v e r t e r s . 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 p - 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 i s 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 , 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 a s s o c i a t e d w i t h t h e 0 . 6 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 . s o f t - s t a r t e a c h c h a n n e l i n t h e a p w 7 1 7 6 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 , 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 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 . 6 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 . s h o r t c i r c u i t p r o t e c t i o n f o r e a c h c h a n n e l , 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 2 1 0 k h z . 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 a g e o n t h e f b a g a i n a p p r o a c h e s 0 . 6 v . 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 ) e n a b l e / s h u t d o w n f o r e a c h c h a n n e l , 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 c h a n n e l 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 s a r e t u r n e d 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 a l l y . for each channel, the over-temperature circuit limits the junction temperature of the APW7176. when the junction temperature exceeds 150 o c , a thermal sensor turns off the power mosfets, allowing the channels to cool down. the thermal sensor allows the converter to start a soft- start process and to regulate the output voltage again after the junction temperature cools by 40 o c . the otp is designed with a 40 o c hysteresis to lower the average m a i n c o n t r o l l o o p junction temperature (t j ) during continuous thermal overload conditions, increasing the lifetime of the device. the APW7176 is a fixed frequency pwm peak current modulation control step-down converter. at light loads, the APW7176 will automatically enter in pulse frequency modulation operation to reduce the dominant switching losses. in pfm operation, the inductor current may reach zero or reverse on each pulse. a zero current comparator turns off the n-channel synchronous mosfet, forcing dcm (discontinuous current mode) operation at light load. these controls get very low quiescent, help to main- tain high efficiency over the complete load range. automoatic pfm/pwm mode switch
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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 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 w h e r e f o s c i s t h e s w i t c h i n g f r e q u e n c y o f a p w 7 1 7 6 a n d d i l i s t h e v a l u e o f t h e m a x i m u m c u r r e n t r i p p l e . i t c a n b e a n y v a l u e o f c u r r e n t r i p p l e t h a t s m a l l e r t h a n t h e m a x i m u m v a l u e y o u c a n a c c e p t . i n o r d e r t o p e r f o r m h i g h e f f i c i e n c y , s e l e c t i n g a l o w d c r e s i s t a n c e i n d u c t o r i s a h e l p f u l w a y . a n o t h e r i m p o r t a n t p a r a m e t e r i s t h e d c c u r r e n t r a t i n g o f t h e i n d u c t o r . t h e m i n i m u m v a l u e o f d c c u r r e n t r a t i n g e q u a l s t h e f u l l l o a d v a l u e o f 1 a , a n d t h e n p l u s t h e h a l f o f t h e c u r r e n t r i p p l e . c h o o s e i n d u c t o r s w i t h s u i t a b l e d c c u r - r e n t r a t i n g t o e n s u r e t h e i n d u c t o r s d o n ? t o p e r a t e i n t h e s a t u r a t i o n . d u e t o t h e h i g h s w i t c h i n g f r e q u e n c y a s 1 . 5 m h z , t h e i n - d u c t o r v a l u e o f t h e a p p l i c a t i o n o f t h e a p w 7 1 7 6 i s u s u a l l y i n t h e r a n g e f r o m 1 m h t o 4 . 7 m h . t h e c r i t e r i o n o f s e l e c t i n g a s u i t a b l e i n d u c t o r d e p e n d s o n i t s m a x i m u m c u r r e n t r i p p l e . t h e m a x i m u m c u r r e n t r i p p l e d e f i n e s a s 4 0 % o f t h e f u l l y l o a d c u r r e n t . i n t h e a p w 7 1 7 6 a p p l i c a t i o n s , t h e m a x i m u m v a l u e o f c u r r e n t r i p p l e i s 4 0 0 m a , t h e 4 0 % o f 1 a . c a l c u l a t e l b y t h e e q u a t i o n ( 1 ) : t h e i n p u t c a p a c i t o r m u s t b e a b l e t o s u p p o r t t h e m a x i - m u m i n p u t o p e r a t i n g v o l t a g e a n d m a x i m u m r m s i n p u t c u r r e n t . t h e b u c k c o n v e r t e r a b s o r b s p u l s e c u r r e n t f r o m i n p u t p o w e r s o u r c e . q 1 q 2 l c out c in v in i(c in ) i in i(q 1 ) i(l ) i(c out ) i out pwm f i g u r e - 1 s h o w s a s c h e m a t i c o f a b u c k c o n v e r t e r . t h e w a v e f o r m s a r e s h o w n a s f i g u r e - 2 . i in i out i l i in i(c in ) i(c out ) i out i(q 1 ) pwm d*t s (1-d)*t s 0a 0a 0a 0a 0a b y o b s e r v i n g t h e w a v e f o r m o f i ( c i n ) , t h e r m s v a l u e o f i ( c i n ) i s ( ) ( ) [ ] ( ) ) 2 .....( d 1 i d i i c i 2 in 2 2 in out in - + - = r e p l a c e d a n d i i n b y f o l l o w i n g r e l a t i o n : ) 4 .....( .......... .......... i d i out in = t h e r m s v a l u e o f i n p u t c a p a c i t o r c u r r e n t e q u a l : w h e n d = 0 . 5 , t h e r m s c u r r e n t o f i n p u t c a p a c i t o r w i l l b e m a x i m u m v a l u e . u s e t h i s v a l u e t o c h o o s e t h e i n p u t c a - p a c i t o r w i t h s u i t a b l e c u r r e n t r a t i n g . f i g u r e - 1 f i g u r e - 2 ( ) ) 5 ..( .......... ) d 1 ( d i c i out in - = ) 3 ( .......... .......... .......... v v d in out = ( ) ) 1 .....( .......... f i 1 v v v v l osc l in out out in d - = i n d u c t o r s e l e c 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
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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 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 . ) i(c out ) 0a d v out1 d i l v out 0.5t s f i g u r e - 3 e v a l u a t e t h e d v o u t 1 b y t h e i d e a l o f e n e r g y e q u a l i z a t i o n . a c c o r d i n g t o t h e d e f i n i t i o n o f q , ) 6 ....( v c t 2 1 i 2 1 2 1 q 1 out out s l d = ? ? ? ? d = w h e r e t s i s t h e i n v e r s e o f s w i t c h i n g f r e q u e n c y a n d t h e d i l i s t h e i n d u c t o r c u r r e n t r i p p l e . m o v e t h e c o u t t o t h e l e f t s i d e t o e s t i m a t e t h e v a l u e o f d v o u t 1 a s e q u a t i o n ( 7 ) . ) 7 ..( .......... .......... .......... c 8 t i v out s l 1 out d = d a s m e n t i o n e d a b o v e , o n e p a r t o f o u t p u t v o l t a g e r i p p l e i s t h e p r o d u c t o f t h e i n d u c t o r c u r r e n t r i p p l e a n d e s r o f o u t - p u t c a p a c i t o r . t h e e q u a t i o n ( 8 ) e x p l a i n s t h e o u t p u t v o l t - a g e r i p p l e e s t i m a t i o n . a p w 7 1 7 6 i s a h i g h e f f i c i e n c y s w i t c h i n g c o n v e r t e r , i t m e a n s l e s s p o w e r l o s s t r a n s f e r r e d i n t o h e a t . d u e t o t h e o n r e - s i s t a n c e d i f f e r e n c e b e t w e e n i n t e r n a l p o w e r p m o s f e t a n d n m o s f e t , t h e p o w e r d i s s i p a t i o n a t h i g h d u t y c y c l e i s g r e a t e r t h a n t h e l o w d u t y c y c l e . t h e w o r s t c a s e i n t h e d r o p o u t o p e r a t i o n i s t h e c o n d u c t i o n l o s s d i s s i p a t e m a i n l y o n t h e i n t e r n a l p o w e r p m o s f e t . t h e p o w e r d i s s i p a t i o n i s n e a r l y d e f i n e d a s : t h e a p w 7 1 7 6 p r o v i d e s i n t e r n a l 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 . 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 r e a c h e s 1 5 0 d e g r e e s c e n t i g r a d e , t h e a p w 7 1 7 6 w i l l t u r n o f f b o t h i n t e r - n a l p o w e r p m o s f e t a n d n m o s f e t . t h e e s t i m a t i o n o f t h e j u n c t i o n t e m p e r a t u r e , t j , i s d e f i n e d a s : ) 10 ....( .......... .......... .......... .......... p t ja d j q = w h e r e t h e q j a i s t h e t h e r m a l r e s i s t a n c e o f t h e p a c k a g e u t i l i z e d b y t h e a p w 7 1 7 6 . o u t p u t v o l t a g e s e t t i n g t h e n a p w 7 1 7 6 h a s t h e a d j u s t a b l e v e r s i o n f o r o u t p u t v o l t - a g e s e t t i n g b y t h e u s e r s . a s u g g e s t i o n o f m a x i m u m v a l u e o f r 2 i s 3 0 0 k w t o k e e p 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 i s p r o g r a m m e d b y t h e e q u a t i o n a s b e l o w : ) 11 .( .......... .......... .......... r r 1 6 . 0 v 2 1 out ? ? ? ? ? + = ( ) ( ) [ ] ) 9 .......( d 1 r d r i p n ds p ds 2 out d - + = - - ) 8 .......( .......... c 8 t esr i v out s l out ? ? ? ? ? + d = d 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 o u t p u t v o l t a g e r i p p l e i s a s i g n i f i c a n t p a r a m e t e r t o e s t i m a t e t h e p e r f o r m a n c e o f a c o n v e r t o r . t h e r e a r e t w o d i s c r e t e c o m p o n e n t s t h a t a f f e c t t h e o u t p u t v o l t a g e r i p p l e t o b e b i g g e r o r s m a l l e r . i t i s r e c o m m e n d e d t o u s e t h e c r i t e r i o n m e n t i o n e d i n t h e " i n d u c t o r s e l e c t i o n " t o c h o o s e a s u i t a b l e i n d u c t o r . t h e n , b a s e d o n t h i s k n o w n i n d u c t o r c u r r e n t r i p p l e , t h e v a l u e a n d e q u i v a l e n t - s e r i e s - r e s i s t a n c e ( e s r ) o f o u t p u t c a p a c i t o r w i l l a f f e c t t h e o u t p u t v o l t a g e r i p p l e t o b e s m a l l e r o r l a r g e r . t h e o u t p u t v o l t a g e r i p p l e c o n s i s t s o f t w o p o r t i o n s , o n e i s t h e p r o d u c t o f e s r a n d i n d u c t o r c u r r e n t r i p p l e , t h e o t h e r p o r t i o n i s t h e f u n c t i o n o f t h e i n - d u c t o r c u r r e n t r i p p l e a n d t h e o u t p u t c a p a c i t a n c e . f i g u r e - 3 i l l u s t r a t e s t h e w a v e f o r m o f t h e r i p p l e v o l t a g e w h i c h i s g e n e r a t e d w h e n t h e i n d u c t o r r i p p l e c u r r e n t c h a r g e s o r d i s c h a r g e s t h e p u r e c a p a c i t o r w i t h o u t t h e e s r . t h e r m a l c o n s i d e r a t i o n fb r 1 r 2 APW7176 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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 w w w . a n p e c . c o m . t w 1 1 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 . ) 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 a n d v i n / g n d w i t h s h o r t a n d w i d e t r a c e 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 h e h i g h c u r r e n t p a t h s ( g n d 1 / g n d 2 , i n 1 / i n 2 , a n d s w 1 / s w 2 ) s h o u l d b e p l a c e d v e r y c l o s e t o t h e d e v i c e w i t h s h o r t , d i r e c t a n d w i d e t r a c e s . 3 . 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 s w 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 . 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 .
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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 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 tdfn3x3-10 note : 1. followed from jedec mo-229 veed-5. pin 1 e d a b a1 a3 s y m b o l min. max. 0.80 0.00 0.18 0.30 2.20 2.70 0.05 1.40 a a1 b d d2 e e2 e l millimeters a3 0.20 ref tdfn3x3-10 0.30 0.50 1.75 0.008 ref min. max. inches 0.031 0.000 0.007 0.012 0.087 0.106 0.055 0.012 0.020 0.70 0.069 0.028 0.002 0.50 bsc 0.020 bsc 0.20 0.008 k 2.90 3.10 0.114 0.122 2.90 3.10 0.114 0.122 pin 1 corner d2 e 2 l e 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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 w w w . a n p e c . c o m . t w 1 3 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 application a h t1 c d d w e1 f 330 ? 2.00 50 min. 12.4+2.00 - 0.00 13.0+0.50 - 0.20 1.5 min. 20.2 min. 12.0 ? 0.30 1.75 ? 0.10 5.5 ? 0.05 p 0 p1 p 2 d 0 d1 t a 0 b 0 k 0 t dfn 3x3 - 10 4.0 ? 0.10 8.0 ? 0.10 2.0 ? 0.05 1.5+0.10 - 0.00 1.5 min. 0.6+0.00 - 0 .40 3.30 ? 0.20 3.30 ? 0.20 1.30 ? 0.20 (mm) d e v i c e s p e r u n i t package type unit quantity t dfn 3x3 - 10 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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 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 tdfn3x3-10 user direction of feed 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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 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 r e l i a b i l i t y t e s t p r o g r a m 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
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 . 1 - m a r . , 2 0 1 1 a p w 7 1 7 6 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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