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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 . 4 - j a n . , 2 0 0 9 a p w 7 1 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 . d u a l m o b i l e - f r i e n d l y p w m c o n t r o l l e r the apw7108 is a dual-channel, constant on- time, and synchronous pwm controller which drives dual n- channel mosfets for each channel. the apw7108 steps down high voltage of a battery to generate low-voltage chipset or ram supplies in notebook computers. the apw7108 provides excellent transient re sponse and accurate dc voltage output in either pfm or pwm m ode. in pfm mode , t he apw7108 provides very high efficiency over light to heavy loads with loading-modu- lated switching frequencies. the forced-pwm mode works nearly at constant frequency for low-noise requirements. the apw7108 is equipped with accurate current- limit, output under-voltag, and output over-voltage protections, perfect for nb applications. a power- on- reset function monitors the voltage on v cc to prevent wrong opera- tion during power on. a soft-start ramps up the output voltage with programmable slew rate to reduce the start-up current. a soft-stop function actively discharges the output capacitors with controlled reverse inductor current. at the end of the soft-stop, the apw7108 forces lgate high to prevent over - voltage in shutdown. the apw7108 has individual enable controls for each channel. pulling both en pin low shuts down the whole chip with low quiescent current close to zero. the apw7108 is available in ssop-28 and qfn4x4-24 packages. 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 adjustable output voltage up to 5.5v - 0.9v reference voltage - 1% accuracy over temperature operates from an i nput b attery v oltage r ange of 5v to 24v or from 3.3v/5v system rail power-on-reset monitoring on vcc pin selectable forced pwm or automatic pfm/pwm mode constant-on-time control scheme - switching frequency compensation for pwm mode - constant switching frequency (ch1: 345khz, ch2: 255khz) in pwm mode with dc output current excellent line and load transient responses adjustable soft-start and soft-stop power-good outputs for both channels adjustable current-limit protection - using sense resistor or mosfet?s r ds(on) 115% over-voltage protection - no negative output voltage occurred 70% under-voltage protection adaptive dead-time control - sensing g-to-s voltage of power mosfets shutdown control for both channels 28-pin ssop (ssop-28) and 4mmx4mm 24-lead qfn (qfn4x4-24) packages lead free and green devices available (rohs compliant) a p p l i c a t i o n s note book computers - chipset/ram supplies as low as 0.9v - 1.8v and 2.5v supplies step-down converters requiring high efficiency 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 v out2 q3 pwm2 q4 v out1 v in +5v~24v pwm1 v cc = 5 v q1 q2 en1 en2 r ocset1 r ocset2 ssop-28
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 2 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 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 cc vcc supply voltage (vcc to gnd) - 0.3 ~ 7 v v in input power voltage (vin to gnd) - 0.3 ~ 28 v v boot boot supply voltage (boot to phase) - 0.3 ~ 7 v v boot - gnd boot supply voltage (boot to gnd) - 0.3 ~ 35 v ugate volta ge (ugate to phase) <400ns pulse width >400ns pulse width - 5 ~ v boot +0.3 - 0.3 ~ v boot +0.3 v lgate voltage (lgate to gnd) <400ns pulse width >400ns pulse width - 5 ~ v cc +0.3 - 0.3 ~ v cc +0.3 v v c c 2 1 l g a t e 1 2 3 g n d 2 2 p h a s e 1 2 4 18 ugate2 isen1 3 17 boot2 boot1 2 16 isen2 14 vout2 en1 4 1 1 p g 2 1 0 p g 1 vout1 5 8 s o f t 1 ugate1 1 9 v i n 7 o c s e t 15 en2 l g a t e 2 2 0 vsen1 6 13 vsen2 1 2 s o f t 2 p h a s e 2 1 9 backside exposed pad apw7108 (qfn4x4-24) top view 24 23 22 25 26 27 28 1 2 3 4 5 6 7 8 9 10 19 20 21 vcc lgate2 pgnd2 phase2 ugate2 boot2 isen2 en2 vout2 vsen2 gnd lgate1 pgnd1 phase1 ugate1 boot1 isen1 en1 vout1 vsen1 11 12 13 14 ocset1 soft1 nc vin 18 15 16 17 ocset2 soft2 pg2 pg1 apw7108 (ssop-28) top view 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 c 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 ) . apw7108 handling code temperature range package code assembly material apw7108 n : xxxxx - date code apw7108 xxxxx apw7108 qa : apw7108 xxxxx xxxxx - date code package code n : ssop-28 qa: qfn4x4-24 operating ambient temperature range i : -40 to 85 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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 3 symbol parameter range unit v cc vcc supply voltage 4.5 ~ 5.5 v v out1 v out2 converter output voltages 0.9 ~ 5.5 v v in1 v in2 converter input voltages 5 ~ 24 v i out1 i out2 converter output currents ~ 20 a r ocset ocset resistance range 39 ~ 200 k w t a ambient temperature - 40 ~ 85 o c t j junction temperature - 40 ~ 125 o c a b s o l u t e m a x i m u m r a t i n g s ( c o n t . ) ( n o t e 1 ) symbol parameter rating unit v phase phase voltage (phase to gnd) <400ns pulse width > 4 00ns pulse width - 5 ~ 35 - 2 ~ 28 v pgnd to gnd voltage - 0.3 ~ 0.3 v v isen isen supply voltage (i sen to gnd) - 0.3 ~ 28 v v pg pg1, pg2 supply voltage (pg1, pg2 to gnd) - 0.3 ~ 7 v t sdr maximum lead soldering temperature, 10 seconds 260 o c note 1 : absolute maximum ratings are those values beyond which the life of a device may be impaired. 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 thermal resistance in free air (note 2 ) ssop - 28 qfn4x4 - 24 80 40 o c/w note 2: q ja is measured with the component mounted on a high effectiv e thermal conductivity test board in free air. 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 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 cc =5v, v in =5~24v and t a = - 4 0 ~ 85 c, unless otherwise specified. typical values are at t a =25c. apw7108 symbol parameter test conditions min . typ . max . unit supply current i cc vcc nominal supply current ugatex and lgatex open, vsenx forced above regulation point - 1.2 3.0 ma i cc_shdn vcc shutdown supply current - - 1.0 m a power - on - reset (por) v ccr rising vcc threshold voltage 4.1 4.2 4.3 v vcc por hysteresis 0. 1 0.2 0.3 v vin pin i vin vin pin sink current - - 35 m a i vin_shdn vin shutdown current - - 1.0 m 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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 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 . ) refer to the typical application circuits. these specifications apply over v cc =5v, v in =5~24v and t a = - 4 0 ~ 85 c, unless otherwise specified. typical values are at t a =25c. apw7108 symbol parameter test conditions min . typ . max . unit reference voltag e v ref reference voltage - 0.9 - accuracy - 1.0 - +1.0 % line regulation v cc = 4.5v to 5.5v, v in = 5~24v - 0.1 - +0.1 % load regulation 0a < i out < 5a; 5v < v in < 24v - 1.0 - +1.0 % pwm converters i vsen vsen pin bias current - 100 - +100 na min imum off - time of ugate - 550 - ns vout pin input impedance v out = 5v - 134 - k w v uv vsen un d er - voltage threshold ~ 2 m s noise filter, vsen falling 65 70 75 % v ov vsen over - voltage threshold ~ 2 m s noise filter, vsen rising 110 115 120 % switching frequ ency pwm1 294 345 396 f sw switching frequency in pwm mode dc output current pwm2 217 255 293 khz mosfet gate drivers ugate source resistance v boot = 5v, i ugate = 0.1a - 1 2 w ugate sink resistance v boot = 5v, i ugate = 0.1a - 0.9 1.8 w lgate so urce resistance v cc = 5v , i lgate = 0.1a - 1 2 w lgate sink resistance v cc = 5v , i lgate = 0.1a - 0.6 1.2 w t d dead - time - 25 - ns pgood and control functions pok is high ?g ~ 3 m s noise filter, vsen is from low to target value 87 92 95 % pgood threshold pok is high ?g ~ 3 m s noise filter, vsen is from high to target value 107 112 117 % pok hysteresys - 3 - % pg 1, pg2 leakage current v pg1,2 = 5.5v - - 1 m a v pg1, 2 pg 1, pg2 voltage low i pg1,2 = - 4ma - 0.5 1 v i sen isen sourcing current by design - - 260 m a continuous - conduction - mode (ccm) enforced (pfm operation inhibited) voutx pulled low - - 0.1 v automatic ccm/pfm operation enabled voutx connected to the output 0.9 - - v soft - st art, soft - stop , and enable i start soft - start current source sourcing current - 4.5 - m a i stop soft - stop current sink sinking current - 2.2 - m a softx pull - low impedance - 2 - k w v st soft - start complete threshold - 1.5 - v soft - start clamp voltage voltage threshold of soft pin - 2.4 - v en voltage low (off) - - 0.8 v en voltage high (on) 2.0 - - 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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 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 c h 1 e f f i c i e n c y v s . o u t p u t c u r r e n t c h 2 e f f i c i e n c y v s . o u t p u t c u r r e n t c h 2 s w i t c h i n g f r e q u e n c y o v e r t e m p e r a t u r e c h 1 s w i t c h i n g f r e q u e n c y o v e r t e m p e r a t u r e c h 1 o u t p u t v o l t a g e v s . o u t p u t c u r r e n t c h 2 o u t p u t v o l t a g e v s . o u t p u t c u r r e n t output current,i out1 (a) o u t p u t v o l t a g e , v o u t 1 ( v ) 2.495 2.498 2.501 2.504 2.507 2.510 0 1 2 3 4 5 6 7 8 9 10 v in1 =10v, pwm v in1 =15v, pwm v in1 =19v, pwm v in1 =10v, pfm/pwm v in1 =15v, pfm/pwm v in1 =19v, pfm/pwm v out1 =2.5v output current,i out2 (a) o u t p u t v o l t a g e , v o u t 2 ( v ) 1.795 1.798 1.801 1.804 1.807 1.81 0 1 2 3 4 5 6 7 8 9 10 v in2 =10v, pwm v in2 =15v, pwm v in2 =19v, pwm v in2 =10v, pfm/pwm v in2 =15v, pfm/pwm v in2 =19v, pfm/pwm v out2 =1.8v junction temperature,t j ( o c) f r e q u e n c y ( k h z ) 295 305 315 325 335 345 355 365 375 385 395 -50 -30 -10 10 30 50 70 90 110 130 150 f r e q u e n c y ( k h z ) junction temperature,t j ( o c) -50 -30 -10 10 30 50 70 90 110 130 150 220 230 240 250 260 270 280 290 output current,i out1 (a) e f f i c i e n c y ( % ) 0 10 20 30 40 50 60 70 80 90 100 0.01 0.1 1 10 v in1 =10v, pwm v in1 =15v, pwm v in1 =19v, pwm v in1 =10v, pfm/pwm v in1 =15v, pfm/pwm v in1 =19v, pfm/pwm v out1 =2.5v output current,i out2 (a) e f f i c i e n c y ( % ) 0 10 20 30 40 50 60 70 80 90 100 0.01 0.1 1 10 v in2 =10v, pwm v in2 =15v, pwm v in2 =19v, pwm v in2 =10v, pfm/pwm v in2 =15v, pfm/pwm v in2 =19v, pfm/pwm v out2 =1.8v
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 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 ( c o n t . ) c h 1 s w i t c h i n g f r e q u e n c y v s . v i n c h 2 s w i t c h i n g f r e q u e n c y v s . v i n c h 2 s w i t c h i n g f r e q u e n c y v s . o u p u t c u r r e n t c h 1 s w i t c h i n g f r e q u e n c y v s . o u p u t c u r r e n t r e f e r e n c e v o l t a g e a c c u r a c y o v e r t e m p e r a t u r e 315 325 335 345 355 365 375 5 7 9 11 13 15 17 19 21 23 25 s w i t c h i n g f r e q u e n c y , f s w ( k h z ) input voltage, v in (v) in pwm mode dc output current o u t p u t v o l t a g e ( v ) 0.891 0.894 0.897 0.9 0.903 0.906 0.909 -50 -30 -10 10 30 50 70 90 110 130 150 junction temperature,t j ( o c) s w i t c h i n g f r e q u e n c y , f s w ( k h z ) output current, i out1 (a) 0 50 100 150 200 250 300 350 0 2 4 6 8 10 400 v out1 =2.5v,pwm v out1 =2.5v,pfm/pwm s w i t c h i n g f r e q u e n c y , f s w ( k h z ) output current, i out2 (a) 0 50 100 150 200 250 0 2 4 6 8 10 v out2= 1.8v,pwm v out2 =1.8v,pfm/pwm 300 230 240 250 260 270 280 5 7 9 11 13 15 17 19 21 23 25 s w i t c h i n g f r e q u e n c y , f s w ( k h z ) input voltage, v in (v) in pwm mode dc output current
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 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 e n a b l e a t z e r o i n i t i a l v o l t a g e o f v o u t e n a b l e b e f o r e e n d o f s o f t - s t o p s h u t d o w n a t i o u t 1 = 5 a s h u t d o w n w i t h s o f t - s t o p a t n o l o a d ch1: v en1 (5v/div) ch2: v pg1 (5v/div) ch3: v soft1 (1v/div) ch4: v out1 (2v/div) time: 5ms/div 1 2 3 4 ch1: v en1 (5v/div) ch2: v pg1 (5v/div) ch3: v soft1 (1v/div) ch4: v out1 (2v/div) time: 2ms/div 1 2 3 4 ch1: v en1 (5v/div) ch2: v pg1 (5v/div) ch3: v soft1 (1v/div) ch4: v out1 (2v/div) time: 2ms/div 1 2 3 4 ch1: v en1 (5v/div) ch2: v pg1 (5v/div) ch3: v soft1 (1v/div) ch4: v out1 (2v/div) time: 5ms/div 1 2 4 3
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 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 ( c o n t . ) u v p , p w m m o d e ( c h 1 ) u v p , p w m m o d e ( c h 2 ) i n p u t s t e p - u p t r a n s i e n t a t p f m m o d e i n p u t s t e p - d o w n t r a n s i e n t a t p f m m o d e ch1: v phase1 (20v/div) ch2: v out1 (2v/div) ch3: i l1 (5a/div) ch4: v out2 (2v/div) time: 100 m s/div 1 2 4 3 ch1: v phase2 (20v/div) ch2: v out2 (2v/div) ch3: i l2 (5a/div) ch4: v out1 (2v/div) time: 200 m s/div 1 2 3 4 ch1: v in (10v/div) ch2: v out1 (ac, 100mv/div) ch3: v out2 (ac, 100mv/div) time: 50 m s/div 1 2 3 i out1 = 80 ma ch1: v in (10v/div) ch2: v out1 (ac, 100mv/div) ch3: v out2 (ac, 50mv/div) time: 50 m s/div 1 2 3 i out1 = 80 ma
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 9 o p e r a t i n g w a v e f o r m s ( c o n t . ) i n p u t s t e p - u p t r a n s i e n t a t p w m m o d e i n p u t s t e p - d o w n t r a n s i e n t a t p w m m o d e m o d e t r a n s i e n t o f p f m t o p w m m o d e t r a n s i e n t o f p w m t o p f m ch1: v in (10v/div) ch2: v out1 (ac, 100mv/div) ch3: v out2 (ac, 100mv/div) time: 20 m s/div 1 2 3 i out1 = 5a ch1: v in (10v/div) ch2: v out1 (ac, 100mv/div) ch3: v out2 (ac, 100mv/div) time: 20 m s/div 1 2 3 i out1 = 5a ch1: v out1 (ac, 100mv/div) ch2: v phase1 (20v/div) ch3: i l1 (5a/div) ch4: v out2 (ac, 100mv/div) time: 10 m s/div 1 2 3 4 i out1 = 0.1a to 5a ch1: v out1 (ac, 100mv/div) ch2: v phase1 (20v/div) ch3: i l1 (5a/div) ch4: v out2 (ac, 100mv/div) time: 10 m s/div 1 2 3 4 i out1 = 5a to 0.1a
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 1 0 o p e r a t i n g w a v e f o r m s ( c o n t . ) l o a d t r a n s i e n t a t p f m m o d e 0 a - > 5 a - > 0 a ( c h 1 ) l o a d t r a n s i e n t a t p w m m o d e 0 a - > 5 a - > 0 a ( c h 1 ) l o a d t r a n s i e n t a t p f m m o d e 0 a - > 5 a - > 0 a ( c h 2 ) l o a d t r a n s i e n t a t p w m m o d e 0 a - > 5 a - > 0 a ( c h 2 ) ch1: v out1 (ac, 50mv/div) ch2: v phase1 (20v/div) ch3: i l1 (5a/div) ch4: v out2 (ac, 50mv/div) time: 20 m s/div 1 2 4 3 i out1 rise/fall time = 1 m s ch1: v out1 (ac, 50mv/div) ch2: v phase1 (20v/div) ch3: i l1 (5a/div) ch4: v out2 (ac, 50mv/div) time: 20 m s/div 1 2 4 3 i out1 rise/fall time = 1 m s ch1: v out1 (ac, 50mv/div) ch2: v phase1 (20v/div) ch3: i l1 (5a/div) ch4: v out2 (ac, 50mv/div) time: 20 m s/div 1 2 4 3 i out2 rise/fall time = 1 m s ch1: v out1 (ac, 50mv/div) ch2: v phase1 (20v/div) ch3: i l1 (5a/div) ch4: v out2 (ac, 50mv/div) time: 20 m s/div 1 2 3 4 i out2 rise/fall time = 1 m 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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 1 1 o p e r a t i n g w a v e f o r m s ( c o n t . ) c u r r e n t - l i m i t a n d u v p r o t e c t i o n s ( c h 1 ) c u r r e n t - l i m i t a n d u v p r o t e c t i o n s ( c h 2 ) s h o r t c i r c u i t t e s t o p e r a t i n g a t l i g h t l o a d o f 1 0 0 m a ( c h 1 ) 1 2 3 4 ch1: v out1 (ac, 100mv/div) ch2: v phase1 (20v/div) ch3: i l1 (2a/div) ch4: v out2 (ac, 100mv/div) time: 10 m s/div in pfm operation ch1: v phase1 (20v/div) ch2: v out1 (2v/div) ch3: i l1 (5a/div) ch4: v out2 (2v/div) time: 10 m s/div 4 3 2 1 ch1: v phase2 (20v/div) ch2: v out1 (2v/div) ch3: i l2 (10a/div) ch4: v out2 (2v/div) time: 1ms/div 1 2 3 4 i out2 rises with slow slew rate ch1: v phase1 (20v/div) ch2: v out1 (2v/div) ch3: i l1 (10a/div) ch4: v out2 (2v/div) time: 2ms/div 1 2 4 3 i out1 rises with slow slew rate
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 1 2 o p e r a t i n g w a v e f o r m s ( c o n t . ) o p e r a t i n g a t h e a v y l o a d o f 5 a ( c h 1 ) ch1: v out1 (ac, 100mv/div) ch2: v phase1 (20v/div) ch3: i l1 (2a/div) ch4: v out2 (ac, 100mv/div) time: 2 m s/div 1 2 3 4 p i n d e s c r i p t i o n pin qfn - 24 ssop - 28 name function 22 1 gnd signal ground for the ic. 23 2 lgate1 output of the low - side mosfet driver (pwm 1). connect this pin to gate of the low - side mosfet. swings from pgnd1 or pgnd to vcc. - 3 pgnd1 power ground of the lgate1 low - side mosfet driver. connect the pin to the source of the low - side mosfet. 24 4 phase1 junction point of the high - side mosfet source, output filter inductor and the low - side mosfet drain. connect this pin to the source of the high - side mosfet. phase1 serve s as the lower supply rail for the ugate1 high - side gate driver. 1 5 ugate1 output of the high - side mosfet driver (pwm 1). connect this pin to gate of the high - side mosfet. 2 6 boot1 supply input for the ugate1 gate driver and an internal level - shift cir cuit. connect to an external capacitor and diode to create a boosted voltage suitable to drive a logic - level n - channel mosfet. 3 7 isen1 current sense pin (pwm 1). this pin is used to monitor the voltage drop across the drain and source of the low - side mo sfet for current limit . for precise current detection , this input can be connected to the optional current sense resistor placed in series with the source of the low - side mosfet. 4 8 en1 enable pin of the pwm 1 controller. the pwm 1 is enabled when en1=1. when both en1 and en2 are low, the chip is disabled and only low leakage current is taken from v cc and v in . 5 9 vout1 selection pin for pwm 1 controller to opera te in either forced pwm or automatic pfm/pwm mode. 6 10 vsen1 output voltage feedback pin ( pwm1). this pin is connected to the resistive divider that set the desired output voltage for pwm 1. the pgood, uvp, and ovp circuits detect this signal to report output voltage status.
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 1 3 p i n d e s c r i p t i o n ( c o n t . ) pin qfn - 24 ssop - 28 name function - 11 ocset1 current - limit threshold setting pin (pwm1). this pin is a buffered 0.9v internal reference voltage. a resistor from this pin to the ground sets the current limit threshold for the converter. 8 12 soft1 soft - start and soft - stop interval setting pin. the soft1 pin can source 4.5a in soft - s t art process or sink 2.2 m a in soft - stop process. the soft1 current charges or discharges the capacitor connected from the pin to the gnd. the output voltage of the converter follows the ramping - up/down voltage on the soft1 pin in the soft - start/soft - stop process with the soft1 pi n voltage as reference. when the soft1 pin voltage is higher than internal reference 0.9v, the error amplifier will use the reference to regulate output voltage. in the event of under - voltage, or en1 shutdown, the soft1 is used by the soft - stop function an d then pulled down though a 2k resistor to the ground after the falling soft1 voltage reaches about 50mv threshold. in soft - stop process, the converter only has sinking capability even though the output voltage is below the regulated voltage. - 13 nc no c omment 9 14 vin battery voltage input pin. 10 15 pg1 power - good output pin of pwm 1. pgood1 is an open drain output used to i ndicate the status of the output voltage. this pin is pulled low when the pwm 1 converter output is out of - 11% ~ +15% of the se t value. 11 16 pg2 power - good output pin of pwm 2 . the function is same as the pg1 pin. 12 17 soft2 soft - start and soft - stop interval setting pin. the function is the same as the soft1 pin. - 18 ocset2 current - limit threshold setting pin (pwm 2 ). this p in is a buffered 0.9v internal reference voltage. a resistor from this pin to ground sets the current - limit threshold for the converter. 13 19 vsen2 output voltage feedback pin. this pin is connected to the resistive divider that set the desired output vo ltage for pwm 2. the pgood, uvp, and ovp circuits use this signal to report output voltage status. 14 20 vout2 selection pin for pwm 2 controller to operate in either forced pwm or automatic pfm/pwm mode. 15 21 en2 enable pin of the pwm 2 controller. the pwm 2 is enabled when en2 = 1. when both en1 and en2 are low, the chip is disabled and only low leakage current is taken from v cc and v in . 16 22 isen2 current sense pin (pwm 2). this pin has the same function as isen1. 17 23 boot2 supply input for the u gate2 gate driver and an internal level - shift circuit. its function is same as boot1. 18 24 ugate2 output of the high - side mosfet driver (pwm 2). connect this pin to gate of the high - side mosfet. 19 25 phase2 junction point of the high - side mosfet source , output filter inductor and the low - side mosfet drain. connect this pin to the source of the high - side mosfet. phase2 serves as the lower supply rail for the ugate2 high - side gate driver. - 26 pgnd2 power ground of the lgate2 low - side mosfet driver. conn ect the pin to the source of the low - side mosfet. 20 27 lgate2 output of the low - side mosfet driver (pwm 2). connect this pin to gate of the low - side mosfet. swings from pgnd2 or pgnd to vcc. 21 28 vcc supply voltage input pin for control circuitry and both low - side mosfet drivers. 7 - ocset current limit threshold setting pin for pwm1 and p wm 2 . this pin is a buffered 0.9v internal reference voltage. a resistor from this pin to the ground sets the current - limit threshold for the converter. thermal pad - pgnd power ground of the both channels ? low - side mosfet driver s . connect the source s of the both channels' low - side mosfet s to the ic thermal pad as close as possible .
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 1 4 ugate1 phase1 boot1 lgate1 pgnd1 a daptive dead- time diode emulation pwm/ pfm transition mode change comp 1 pg1 en1 vout1 vcc gnd por enable bias supplies reference fault latch ton1 generator vsen1 soft1 isen1 ocset1 vin current limit 1 0.9 v v ocset1 89% v ref 115% v ref 0.9v v ref 4.5 m a -2.2 m a lgate1 error comparator1 140 w 70% v ref ugate1 soft-start soft-stop ov1 uv1 ov1 v cc v cc i ocset1 r r 11.4 i sen1 ugate2 phase2 boot2 lgate2 pgnd2 a daptive dead- time diode emulation pwm/ pfm transition mode change comp 2 pg2 en2 vout2 ton2 generator vsen2 soft2 isen2 ocset2 current limit 2 0.9 v v ocset2 89% v ref 115% v ref 0.9v v ref 4.5 m a -2.2 m a lgate2 error comparator2 140 w 70% v ref ugate2 soft-start soft-stop ov2 uv2 ov2 v cc i ocset2 r i sen2 r 11.4 b l o c k d i a g r a m 1. ssop-28
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 1 5 b l o c k d i a g r a m 2. qfn4x4-24 ugate1 phase1 boot1 lgate1 a daptive dead-time diode emulation pwm/pfm transition mode change comp 1 pg1 en1 vout1 vcc gnd por enable bias supplies reference fault latch ton1 generator vsen1 soft1 isen1 ocset vin current limit 1 0.9 v v ocset 89% v ref 115% v ref 0.9v v ref 4.5 m a -2.2 m a lgate1 error comparator1 140 w 70% v ref ugate1 soft-start soft-stop ov1 uv1 ov1 v cc v cc i ocset1 r r 11.4 i sen1 ugate2 phase2 boot2 lgate2 pgnd a daptive dead-time diode emulation pwm/pfm transition mode change comp 2 pg2 en2 vout2 ton2 generator vsen2 soft2 isen2 current limit 2 89% v ref 115% v ref 0.9v v ref 4.5 m a -2.2 m a lgate2 error comparator2 140 w 70% v ref ugate2 soft-start soft-stop ov2 uv2 ov2 v cc i ocset2 r i sen2 r 11.4
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 1 6 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 1. ssop-28 2. qfn4x4-24 gnd vcc apw7108 v in +5v bias supply v cc c1 4.7 m f boot2 ugate2 phase2 lgate2 isen2 vsen2 pg2 vout2 c12 0.15 m f c10 150 m fx2 l2 4.7 m h c8 10 m f r8 10k r9 10k q3 apm4412 d2 bat54w v out2 1.8v en2 soft2 ocset2 r7 1k r6 0 boot1 ugate1 phase1 lgate1 isen1 vsen1 pg1 vout1 c6 0.15 m f c4 150 m fx2 l1 4.7 m h c2 10 m f r3 17.8k r4 10k q1 apm4412 d1 bat54w v out1 2.5v en1 soft1 ocset1 r2 1k r1 0 c11 10nf c5 10nf c13 10nf r10 100k c7 10nf r5 100k pgnd2 pgnd1 c9 4.7 m f c3 4.7 m f vin q2 apm4412 q4 apm4412 gnd vcc apw7108 v in +5v bias supply v cc c1 4.7 m f boot2 ugate2 phase2 lgate2 isen2 vsen2 pg2 vout2 c12 0.15 m f c10 150 m fx2 l2 4.7 m h c8 10 m f r8 10k r9 10k q3 apm4412 d2 bat54w v out2 1.8v en2 soft2 r7 1k r6 0 boot1 ugate1 phase1 lgate1 isen1 vsen1 pg1 vout1 c6 0.15 m f c4 150 m fx2 l1 4.7 m h c2 10 m f r3 17.8k r4 10k q1 apm4412 d1 bat54w v out1 2.5v en1 soft1 ocset r2 1k r1 0 c11 10nf c5 10nf c13 10nf c7 10nf r5 100k pgnd c9 4.7 m f c3 4.7 m f vin q2 apm4412 q4 apm4412
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 1 7 f u n c t i o n d e s c r i p t i o n constant-on-time pwm controller with input feed- forward t h e c o n s t a n t - o n - t i m e c o n t r o l a r c h i t e c t u r e i s a p s e u d o - f i x e d f r e q u e n c y w i t h i n p u t v o l t a g e f e e d - f o r w a r d . t h i s a r c h i t e c t u r e r e l i e s o n t h e o u t p u t f i l t e r c a p a c i t o r ? s e f f e c t i v e s e r i e s r e s i s t a n c e ( e s r ) t o a c t a s a c u r r e n t - s e n s e r e s i s t o r , t h e r e f o r e , t h e o u t p u t r i p p l e v o l t - a g e p r o v i d e s t h e p w m r a m p s i g n a l . i n p f m o p e r a t i o n , t h e h i g h - s i d e s w i t c h o n - t i m e c o n t r o l l e d b y t h e o n - t i m e g e n - e r a t o r i s d e t e r m i n e d s o l e l y b y a o n e - s h o t w h o s e p u l s e w i d t h i s i n v e r s e l y p r o p o r t i o n a l t o i n p u t v o l t a g e a n d d i - r e c t l y p r o p o r t i o n a l t o o u t p u t v o l t a g e . i n p w m o p e r a t i o n , t h e h i g h - s i d e s w i t c h o n - t i m e i s d e t e r m i n e d b y a s w i t c h - i n g f r e q u e n c y c o n t r o l c i r c u i t i n t h e o n - t i m e g e n e r a t o r b l o c k f o r e a c h c h a n n e l . t h e s w i t c h i n g f r e q u e n c y c o n t r o l c i r c u i t s e n s e s t h e s w i t c h i n g f r e q u e n c y o f t h e h i g h - s i d e s w i t c h a n d k e e p s r e g u l a t i n g i t a t a c o n s t a n t f r e q u e n c y i n p w m m o d e . t h e d e s i g n i m p r o v e s t h e f r e q u e n c y v a r i a t i o n a n d i s m o r e o u t s t a n d i n g t h a n a c o n v e n t i o n a l c o n s t a n t - o n - t i m e c o n t r o l l e r w h i c h h a s l a r g e s w i t c h i n g f r e q u e n c y v a r i a t i o n o v e r i n p u t v o l t a g e , o u t p u t c u r r e n t a n d t e m p e r a t u r e . b o t h i n p f m a n d p w m , t h e o n - t i m e g e n e r a t o r , w h i c h s e n s e s i n p u t v o l t a g e o n v i n p i n , p r o v i d e s v e r y f a s t o n - t i m e r e - s p o n s e t o i n p u t l i n e t r a n s i e n t s . t h e o n - t i m e s f o r c h a n n e l 2 a r e s e t 3 5 % h i g h e r t h a n t h e o n - t i m e s f o r c h a n n e l 1 . t h i s i s d o n e t o p r e v e n t a u d i o - f r e q u e n c y ? b e a t i n g ? b e t w e e n t h e t w o s i d e s , w h i c h s w i t c h a s y n c h r o n o u s l y f o r e a c h s i d e . a n o t h e r o n e - s h o t s e t s a m i n i m u m o f f - t i m e ( t y p i c a l : 5 5 0 n s ) . t h e o n - t i m e o n e - s h o t i s t r i g g e r e d i f t h e e r r o r c o m p a r a t o r i s h i g h , t h e l o w - s i d e s w i t c h c u r r e n t i s b e - l o w t h e c u r r e n t - l i m i t t h r e s h o l d , a n d t h e m i n i m u m o f f - t i m e o n e - s h o t h a s t i m e d o u t . p f m m o d e i n p f m m o d e , a n a u t o m a t i c s w i t c h o v e r t o p u l s e - f r e - q u e n c y m o d u l a t i o n ( p f m ) t a k e s p l a c e a t l i g h t l o a d s . t h i s s w i t c h o v e r i s e f f e c t e d b y a c o m p a r a t o r t h a t t r u n c a t e s t h e l o w - s i d e s w i t c h o n - t i m e a t t h e i n d u c t o r c u r r e n t ? s z e r o c r o s s i n g . t h i s m e c h a n i s m c a u s e s t h e t h r e s h - o l d b e t w e e n p f m a n d p w m o p e r a t i o n t o c o i n c i d e w i t h t h e b o u n d a r y b e t w e e n c o n t i n u o u s a n d d i s c o n - t i n u o u s i n d u c t o r - c u r r e n t o p e r a t i o n ( a l s o k n o w n a s t h e w h e r e f s w i s t h e n o m i n a l s w i t c h i n g f r e q u e n c y o f t h e c o n - v e r t e r i n p w m m o d e . t h i s d e s i g n p r o v i d e s a h y s t e r e s i s o f c o n v e r t e r ? s o u t p u t c u r r e n t t o p r e v e n t w r o n g o r r e p e a t e d l y p f m / p w m h a n d o f f w i t h c o n s t a n t o u t p u t c u r r e n t . t h e l o a d c u r r e n t a t h a n d o f f f r o m p f m t o p w m m o d e i s g i v e n b y : t h e l o a d c u r r e n t a t h a n d o f f f r o m p w m t o p f m m o d e i s g i v e n b y : t h e r e f o r e , t h e i l o a d ( p f m t o p w m ) i s 1 . 5 t i m e o f t h e i l o a d ( p w m t o p f m ) . f o r c e d p w m m o d e t h e f o r c e d - p w m m o d e d i s a b l e s t h e z e r o - c r o s s i n g c o m p a r a t o r , w h i c h c o n t r o l s t h e l o w - s i d e s w i t c h o n t i m e . t h i s c a u s e s t h e l o w - s i d e g a t e - d r i v e w a v e f o r m t o b e c o m e t h e c o m p l e m e n t o f t h e h i g h - s i d e g a t e - d r i v e w a v e f o r m . t h i s i n t u r n c a u s e s t h e i n d u c t o r c u r r e n t t o r e v e r s e a t l i g h t l o a d s w h i l e u g a t e m a i n t a i n s a d u t y f a c - t o r o f v o u t / v i n . t h e b e n e f i t o f f o r c e d - p w m m o d e i s t o k e e p t h e s w i t c h i n g f r e q u e n c y f a i r l y c o n s t a n t . f o r c e d - p w m m o d e i s t h e m o s t u s e f u l f o r r e d u c i n g a u d i o f r e q u e n c y n o i s e , i m p r o v i n g l o a d - t r a n s i e n t r e s p o n s e , a n d p r o v i d i n g s i n k - c u r r e n t c a p a b i l i t y f o r d y n a m i c o u t p u t v o l t a g e a d j u s t m e n t . in out sw pfm - on v v f 1.5 t = in out sw out in pfm on out in pwm) to load(pfm v v f 1.5 2l v - v t l v - v 2 1 i = = - in out sw out in pwm on out in pfm) to load(pwm v v f 1 2l v - v t l v - v 2 1 i = = - c r i t i c a l c o n d u c t i o n p o i n t ) . t h e o n - t i m e o f p f m m o d e i s d e s i g n e d a t 1 . 5 t i m e o f t h e n o m i n a l o n - t i m e o f p w m m o d e . t h e o n - t i m e o f p f m i s g i v e n b y : p o w e r - o n - r e s e t a p o w e r - o n - r e s e t ( p o r ) f u n c t i o n i s d e s i g n e d t o p r e v e n t w r o n g l o g i c c o n t r o l s w h e n t h e v c c v o l t a g e i s l o w . t h e p o r f u n c t i o n c o n t i n u a l l y m o n i t o r s t h e b i a s s u p p l y v o l t - a g e o n t h e v c c p i n i f a t l e a s t o n e o f t h e e n a b l e p i n s i 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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 1 8 f u n c t i o n d e s c r i p t i o n ( c o n t . ) soft rise t 0.6 t = p o w e r - o n - r e s e t s o f t - s t a r t / s o f t - s t o p t h e t i m e t h a t t a k e s t h e o u t p u t v o l t a g e t o c o m e i n t o r e g u l a t i o n c a n b e o b t a i n e d f r o m t h e f o l l o w i n g e q u a t i o n : d u r i n g t h e s o f t - s t a r t s t a g e b e f o r e t h e p g o o d p i n i s r e a d y , t h e u n d e r - v o l t a g e p r o t e c t i o n i s p r o h i b i t e d . t h e o v e r - v o l t a g e a n d c u r r e n t - l i m i t p r o t e c t i o n f u n c t i o n s a r e e n a b l e d . i f t h e o u t p u t c a p a c i t o r h a s r e s i d u e v o l t a g e b e f o r e s t a r t - u p , b o t h l o w - s i d e a n d h i g h - s i d e m o s f e t s a r e i n o f f - s t a t e u n t i l t h e s o f t - s t a r t c a p a c i t o r c h a r g e s e q u a l t o t h e v s e n p i n v o l t a g e . t h i s w i l l e n s u r e t h e o u t p u t v o l t a g e s t a r t s f r o m i t s e x i s t i n g v o l t a g e l e v e l . i n t h e e v e n t o f u n d e r - v o l t a g e o r s h u t d o w n , t h e s o f t p i n i s u s e d b y t h e s o f t - s t o p f u n c t i o n . t h e s o f t - s t o p f u n c t i o n d i s c h a r g e s t h e v o l t a g e o n s o f t p i n w i t h t h e i n t e r n a l 2 . 2 m a c u r r e n t s i n k . t h e c h a n n e l w i t h s o f t - s t o p e n a b l e d g r a d u a l l y r a m p s d o w n t h e o u t p u t v o l t a g e , f o l l o w i n g t h e s o f t v o l t a g e , b y c o n t r o l l i n g t h e l o w - s i d e m o s f e t w o r k - u n d e r - v o l t a g e p r o t e c t i o n ( u v p ) i n t h e o p e r a t i o n a l p r o c e s s , i f a s h o r t - c i r c u i t o c c u r s , t h e o u t p u t v o l t a g e w i l l d r o p q u i c k l y . w h e n l o a d c u r r e n t i s b i g g e r t h a n c u r r e n t - l i m i t t h r e s h o l d v a l u e , t h e o u t p u t v o l t a g e w i l l f a l l o u t o f t h e r e q u i r e d r e g u l a t i o n r a n g e . t h e u n d e r - v o l t a g e c o n t i n u a l l y m o n i t o r s t h e v s e n v o l t a g e a f t e r s o f t - s t a r t i s c o m p l e t e d . i f a l o a d s t e p i s s t r o n g e n o u g h t o p u l l t h e o u t p u t v o l t a g e l o w e r t h a n t h e u n d e r - v o l t a g e t h r e s h o l d , t h e o f f e n d i n g c h a n n e l p u l l s l o w t h e p g o o d i m m e d i a t e l y a n d s t a r t s a s o f t - s t o p p r o c e s s t o s h u t d o w n t h e o u t p u t g r a d u a l l y . t h e o f f e n d i n g c h a n n e l i s l a t c h e d o f f w h e n t h e s o f t - s t o p p r o c e s s i s c o m p l e t e d . t h e u n d e r - v o l t a g e t h r e s h o l d i s 7 0 % o f t h e n o m i n a l o u t - p u t v o l t a g e . t h e u n d e r v o l t a g e c o m p a r a t o r h a s a b u i l t - i n 2 s n o i s e f i l t e r t o p r e v e n t t h e c h i p f r o m w r o n g u v p s h u t - d o w n c a u s e d b y n o i s e . t o g g l i n g b o t h e n a b l e p i n s t o l o w , o r r e c y c l i n g v c c , w i l l c l e a r t h e l a t c h a n d b r i n g t h e c h i p b a c k t o o p e r a t i o n . i n g a s a s i n k i n g l i n e a r r e g u l a t o r . t h e s o f t - s t o p p r o c e s s i s c o m p l e t e d w h e n t h e f a l l i n g s o f t v o l t a g e r e a c h e s a b o u t 5 0 m v ( t y p i c a l ) t h r e s h o l d . a t t h i s m o m e n t , t h e l g a t e g o e s h i g h l e v e l w i t h l a t c h a n d s o f t p u l l s l o w b y u s i n g t h e i n t e r n a l 2 k w r e s i s t o r t o t h e g r o u n d . t h e l a t c h c a n b e r e - s e t b y c y c l i n g b o t h o f t h e e n s i g n a l s o r v c c p o w e r - o n - r e s e t s i g n a l . o v e r - v o l t a g e p r o t e c t i o n ( o v p ) the over-voltage function monitors the output voltage by vsen pin. t he v sen voltage should increase over 115% of the reference voltage due to the high- side mosfet failure or for other reasons, and the over - voltage pro- tection comparator designed with a 2 m s noise filter will force the low-side mosfet gate driver to be high. this action actively pulls down the output voltage and eventu- ally attempts to blow the battery fuse. as soon as the out- put voltage is within regulation, the ovp comparator is disengaged. the chip will restore its normal operation. when the ovp occurs, the pgood will drop to low as well. this ovp scheme only clamps the voltage overshoot and does not invert the output voltage when other wise activated with a continuously high output from low -side mosfet driver-a common problem for ovp schemes with a latch. a 4.5 c 1.5v t soft soft m = s e t h i g h . w h e n t h e r i s i n g v c c v o l t a g e r e a c h e s t h e r i s - i n g p o r v o l t a g e t h r e s h o l d ( 4 . 2 v t y p i c a l ) , t h e p o r s i g - n a l g o e s h i g h a n d t h e c h i p i n i t i a t e s s o f t - s t a r t o p e r a - t i o n s f o r t h e e n a b l e d c h a n n e l s . t h i s v o l t a g e s h o u l d d r o p l o w e r t h a n 4 v ( t y p i c a l ) , t h e p o r d i s a b l e s t h e c h i p . when soft-start is initiated, the voltage on the soft pin of the enabled channel starts to ramp up gradually with the internal 4.5 m a current charging the soft-start capacitor. the output voltage follows the soft-start voltage with the converter operating in pwm mode . when the soft pin voltage reaches 0.9v, the output voltage comes into regulation. when the soft voltage reaches 1.5v, the power-good (pgood) is enabled. even though the soft pin voltage contin ues to rise after reaching 1.5v, this voltage does not affect the output voltage. the maxi- mum soft voltage is clamped about 2.4v. the soft-start time (the time from the moment when en becomes high to the moment when pgood is reported) is determined by the following equation:
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 1 9 f u n c t i o n d e s c r i p t i o n ( c o n t . ) t h e c u r r e n t - l i m i t c i r c u i t e m p l o y s a n u n i q u e ? v a l l e y ? c u r - r e n t s e n s i n g a l g o r i t h m ( f i g u r e 1 ) . i f t h e m a g n i t u d e o f t h e c u r r e n t - s e n s e s i g n a l a t i s e n p i n i s a b o v e t h e c u r - r e n t - l i m i t t h r e s h o l d , t h e p w m i s n o t a l l o w e d t o i n i t i a t e a n e w c y c l e . t h e a c t u a l p e a k c u r r e n t i s g r e a t e r t h a n t h e c u r - r e n t - l i m i t t h r e s h o l d b y a n a m o u n t e q u a l s t o 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 r e f o r e , t h e e x a c t c u r r e n t - l i m i t c h a r a c - t e r i s t i c a n d m a x i m u m l o a d c a p a b i l i t y a r e t h e f u n c t i o n o f t h e s e n s e r e s i s t a n c e , i n d u c t o r v a l u e , a n d b a t t e r y v o l t a g e . t h e c u r r e n t s e n s i n g p i n c a n s o u r c e u p t o 2 6 0 a . t h e c u r r e n t s e n s e r e s i s t o r r i s e n a n d o c s e t r e s i s t o r r o c s e t c a n b e a d j u s t e d s i m u l t a n e o u s l y f o r t h e s a m e c u r r e n t - l i m i t t h r e s h o l d l e v e l . t h e r e l a t i o n s h i p b e t w e e n t h e s a m p l e d c u r r e n t a n d m o s f e t c u r r e n t i s g i v e n b y : p o w e r g o o d i n d i c a t o r i n t h e s o f t - s t a r t p r o c e s s , t h e p g o o d i s a n o p e n - d r a i n a n d e s t a b l i s h e d a f t e r t h e s o f t p i n v o l t a g e i s a b o v e 1 . 5 v . i n n o r m a l o p e r a t i o n , t h e p g o o d w i n d o w i s f r o m 8 9 % t o 1 1 5 % o f t h e c o n v e r t e r ? s r e f e r e n c e v o l t a g e . t h e v s e n p i n h a s t o s t a y w i t h i n t h i s w i n d o w f o r p g o o d t o b e h i g h . s i n c e t h e v s e n p i n i s u s e d f o r b o t h f e e d b a c k a n d m o n i - t o r i n g p u r p o s e s , t h e o u t p u t v o l t a g e d e v i a t i o n c a n b e c o u p l e d d i r e c t l y t o t h e v s e n p i n b y t h e c a p a c i t o r i n p a r a l l e l w i t h t h e v o l t a g e d i v i d e r a s s h o w n i n t h e t y p i c a l a p p l i c a t i o n s . i n o r d e r t o p r e v e n t f a l s e p g o o d d r o p , c a p a c i t o r s n e e d t o p a r a l l e l a t t h e o u t p u t t o c o n f i n e t h e v o l t a g e d e v i a t i o n w i t h s e - v e r e l o a d s t e p t r a n s i e n t . t h e p g o o d c o m p a r a t o r h a s a b u i l t - i n 3 s n o i s e f i l t e r . w h e n p o r = 0 , e n = 0 , o r a f t e r u v p , t h e p g o o d i s p u l l e d l o w r e g a r d l e s s o f t h e o u t p u t v o l t a g e . e n a b l e c o n t r o l when the en pin is high (en=1), the pwm is enabled and the soft-start is initiated. when both en1 and en2 are low (en=0), the chip is in the shutdown and only low leakage current is taken from v cc and v in . in shutdown mode, lgate will be pulled high. c u r r e n t - l i m i t b oth pwm controllers use the low -side mosfets on-re- sistance r ds(on) , to monitor the current for protection against short en ed outputs. the sensed current from the isen pin is compared with a current set by a resis- tor connected from the ocset pin to the ground: d ds(on) isen sen i r 140) (r i = + w h e r e , i o c i s a d e s i r e d c u r r e n t - l i m i t t h r e s h o l d a n d r i s e n i s t h e v a l u e o f t h e c u r r e n t s e n s e r e s i s t o r c o n - n e c t e d t o t h e i s e n p i n . t h e 8 a i s t h e o f f s e t c u r r e n t a d d e d o n t o p o f t h e s e n s e d c u r r e n t f r o m t h e i s e n p i n f o r i n t e r n a l c i r c u i t b i a s i n g . time i n d u c t o r c u r r e n t 0 i peak i out i oc figure 1. current limit algorithm a 8 140 r r i 10.3 r isen ds(on) oc ocset m + w + = which means the current sensing pin will sourc e current to make the voltage drop on the mosfet equal s to the voltage generated on the sensing resistor, plus the internal resistor, along the isen pin current flowing path.
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 2 0 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 s w 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 t h e r e g u l a t o r . a l t h o u g h i n c r e a s e t h e i n d u c t o r v a l u e a n d f r e q u e n c y w o u l d r e d u c e t h e r i p p l e c u r r e n t a n d v o l t a g e , t h e r e i s a t r a d e o f f b e t w e e n t h e i n d u c t o r ? s r i p p l e c u r r e n t a n d t h e r e g u l a t o r l o a d t r a n s i e n t r e s p o n s e t i m e . a s m a l l e r i n d u c t o r w i l l g i v e t h e r e g u l a t o r a f a s t e r l o a d t r a n s i e n t r e s p o n s e a t t h e e x p e n s e o f h i g h e r r i p p l e c u r r e n t . i n c r e a s i n g t h e s w i t c h i n g f r e q u e n c y ( f s w ) a l s o r e - d u c e s t h e r i p p l e c u r r e n t a n d v o l t a g e , b u t i t w i l l i n - c r e a s e t h e s w i t c h i n g l o s s o f t h e m o s f e t s a n d t h e p o w e r d i s s i p a t i o n o f t h e c o n v e r t e r . t h e m a x i m u m r i p p l e c u r - r e n t o c c u r s a t t h e m a x i m u m i n p u t v o l t a g e . a g o o d s t a r t i n g p o i n t i s t o c h o o s e t h e r i p p l e c u r r e n t t o b e a p p r o x i m a t e l y 3 0 % o f t h e m a x i m u m o u t p u t c u r r e n t . o n c e t h e i n d u c - t a n c e v a l u e h a s b e e n c h o s e n , s e l e c t a n i n d u c t o r t h a t i s in out v v d = in out sw out in ripple v v l f v - v 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 o u t p u t v o l t a g e r i p p l e a n d t h e t r a n s i e n t v o l t a g e d e - v i a t i o n a r e f a c t o r s t h a t h a v e t o b e t a k e n i n t o c o n s i d - e r a t i o n w h e n s e l e c t i n g a n o u t p u t c a p a c i t o r . h i g h e r c a p a c i t o r v a l u e a n d l o w e r e s r r e d u c e t h e o u t p u t r i p p l e a n d t h e l o a d t r a n s i e n t d r o p . t h e r e f o r e , i t ? s i m p o r t a n t t o s e l e c t h i g h p e r f o r m a n c e l o w e s r c a p a c i t o r s t h a t a r e i n - t e n d e d f o r s w i t c h i n g r e g u l a t o r a p p l i c a t i o n s . i n a d d i t i o n t o h i g h f r e q u e n c y n o i s e r e l a t e d m o s f e t t u r n - o n a n d t u r n - o f f , t h e o u t p u t v o l t a g e r i p p l e i n c l u d e s t h e c a p a c i - t a n c e v o l t a g e d r o p a n d e s r v o l t a g e d r o p c a u s e d b y t h e a c p e a k - t o - p e a k c u r r e n t . t h e s e t w o v o l t a g e s c a n b e r e p r e s e n t e d b y : the inductor value determises the inductor ripple current and affects the load transient reponse. higher inductor value reduces the inductor?s ripple current and induces lower output ripple voltage. the ripple current and ripple voltage can be approxminated by: c a p a b l e o f c a r r y i n g t h e r e q u i r e d p e a k c u r r e n t w i t h o u t g o i n g i n t o s a t u r a t i o n . i n s o m e t y p e s o f i n d u c t o r s , e s - p e c i a l l y c o r e t h a t i s m a d e o f f e r r i t e , t h e r i p p l e c u r - r e n t w i l l i n c r e a s e a b r u p t l y w h e n i t s a t u r a t e s . t h i s w i l l r e s u l t i n a l a r g e r o u t p u t r i p p l e v o l t a g e . esr ripple esr sw out ripple out c r i v f 8c i v = d = d these two components constitute a large portion of the total output voltage ripple. in some applications, multiple capacitors have to be paralleled to achieve the desired esr value. if the output of the converter has to support another load with high pulsating current, more capaci- tors are needed in order to reduce the equivalent esr and suppress the voltage ripple to a tolerable level. a small decoupling capacitor in parallel for bypassing the noise is also recommended, and the voltage rating of the output capacitors are also must be considered. to support a load transient that is faster than the switching frequency, more capacitors have to be used to reduce the voltage excursion during load step change. another aspect of the capacitor selection is that the total ac current going through the capaci tors has to be less than the rated rms current specified on the ca- pacitors to prevent the capacitor from over-heating. o u t p u t v o l t a g e 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 c a n b e a d j u s t a b l e f r o m 0 . 9 v t o 5 . 5 v w i t h a r e s i s t o r - d i v i d e r . u s i n g 1 % o r b e t t e r r e s i s t o r s f o r t h e r e s i s t i v e d i v i d e r i s r e c o m m e n d e d . t h e v s e n p i n i s t h e i n v e r t e r i n p u t o f t h e e r r o r a m p l i f i e r , a n d t h e r e f e r e n c e v o l t a g e i s 0 . 9 v . t a k e a p w 7 1 0 8 a s t h e e x a m p l e , t h e o u t p u t v o l t a g e i s d e t e r m i n e d b y : where r1 is the resistor connected from v out x to vsen x and r gnd is the resistor connected from vsenx to the gnd. ? ? ? ? ? + = gnd outx r r1 1 0.9 v o u t p u t i n d u c t o r s e l e c t i o n t h e d u t y c y c l e o f a b u c k c o n v e r t e r i s t h e f u n c t i o n o f t h e i n p u t v o l t a g e a n d o u t p u t v o l t a g e . o n c e a n o u t p u t v o l t a g e i s f i x e d , i t c a n b e w r i t t e n a s : 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 i s c h o s e n b a s e d o n t h e v o l t a g e r a t i n g a n d t h e r m s c u r r e n t r a t i n g . f o r r e l i a b l e o p e r a 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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 2 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 . ) i n p u t c a p a c i t o r s e l e c t i o n s e l e c t t h e c a p a c i t o r v o l t a g e r a t i n g t o b e a t l e a s t 1 . 3 t i m e s h i g h e r t h a n 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 m a x i m u m r m s c u r r e n t r a t i n g r e q u i r e m e n t i s a p p r o x i m a t e l y i o u t / 2 , w h e r e i o u t i s t h e l o a d c u r r e n t . d u r i n g p o w e r u p , t h e i n p u t c a p a c i t o r s h a v e t o h a n d l e l a r g e a m o u n t o f s u r g e c u r r e n t . i n l o w - d u t y n o t e b o o k a p p l i a c t i o n s , c e r a m i c c a - p a c i t o r s a r e r e c o m m e n d e d . t h e c a p a c i t o r s m u s t b e c o n - n e c t e d b e t w e e n t h e d r a i n o f h i g h - s i d e m o s f e t a n d t h e s o u r c e o f l o w - s i d e m o s f e t w i t h v e r y l o w - i m p e a d a n c e p c b l a y o u t . m o s f e t s e l e c t i o n t h e a p p l i c a t i o n f o r a n o t e b o o k b a t t e r y w i t h a m a x i m u m v o l t - a g e o f 2 4 v , a t l e a s t a m i n i m u m 3 0 v m o s f e t s s h o u l d b e u s e d . t h e d e s i g n h a s t o t r a d e o f f t h e g a t e c h a r g e w i t h t h e r ds(on) o f t h e m o s f e t : f o r t h e l o w - s i d e m o s f e t , b e f o r e i t i s t u r n e d o n , t h e b o d y d i o d e h a s b e e n c o n d u c t e d . t h e l o w - s i d e m o s f e t d r i v e r w i l l n o t c h a r g e t h e m i l l e r c a p a c i t o r o f t h i s m o s f e t . i n t h e t u r n i n g - o f f p r o c e s s o f t h e l o w - s i d e m o s f e t , t h e l o a d c u r r e n t w i l l s h i f t t o t h e b o d y d i o d e f i r s t . t h e h i g h d v / d t o f t h e p h a s e n o d e v o l t a g e w i l l c h a r g e t h e m i l l e r c a p a c i t o r t h r o u g h t h e l o w - s i d e m o s f e t d r i v e r s i n k i n g c u r r e n t p a t h . t h i s r e s u l t s i n m u c h l e s s s w i t c h i n g l o s s o f t h e l o w - s i d e m o s f e t s . t h e d u t y c y c l e i s o f t e n v e r y s m a l l i n h i g h b a t t e r y v o l t a g e a p p l i c a t i o n s , a n d t h e l o w - s i d e m o s f e t w i l l c o n - d u c t m o s t o f t h e s w i t c h i n g c y c l e ; t h e r e f o r e , t h e less the r ds(on) o f t h e l o w - s i d e m o s f e t l o s s , t h e l e s s t h e p o w e r l o s s . t h e g a t e c h a r g e f o r t h i s m o s f e t i s u s u - a l l y o f s e c o n d a r y c o n s i d e r a t i o n . t h e h i g h - s i d e m o s f e t d o e s n o t h a v e t h e z e r o v o l t a g e s w i t c h - i n g c o n d i t i o n , a n d b e c a u s e i t c o n d u c t s f o r l e s s t i m e c o m p a r e d t o t h e l o w - s i d e m o s f e t , t h e s w i t c h i n g l o s s t e n d s t o b e d o m i n a n t . p r i o r i t y s h o u l d b e g i v e n t o t h e m o s f e t s w i t h l e s s g a t e c h a r g e , s o t h a t b o t h t h e g a t e d r i v e r l o s s a n d s w i t c h i n g l o s s w i l l b e m i n i m i z e d . t h e s e l e c t i o n o f t h e n - c h a n n e l p o w e r m o s f e t s a r e d e t e r m i n e d b y t h e r ds(on) , r e v e r s i n g t r a n s f e r c a p a c i - t a n c e ( c r s s ) a n d m a x i m u m o u t p u t c u r r e n t r e q u i r e m e n t . t h e l o s s e s i n t h e m o s f e t s h a v e t w o c o m p o n e n t s : p high-side = i out 2 (1+ tc)(r ds(on) )d + (0.5)( i out )(v in )( t sw )f s w p low-side = i out 2 (1+ tc)(r ds(on) )(1-d) where i out is the load current tc is the temperature dependency of r ds(on) f sw is the switching frequency t sw is the switching interval d is the duty cycle note that both mosfets have conduction losses while the high-side mosfet include s an additional tran- sition loss. the switching internal, t sw , is the func- tion of the reverse transfer capacitance c rss . the (1+tc) term is to factor in the temperature dependency of the r ds (on) and can be extracted from the ?r ds(on) vs tempera- ture? curve of the power mosfet. l a y o u t c o n s i d e r a t i o n i n a n y h i g h s w i t c h i n g f r e q u e n c y c o n v e r t e r , a c o r r e c t l a y o u t i s i m p o r t a n t t o e n s u r e p r o p e r o p e r a t i o n o f t h e r e g u l a t o r . w i t h p o w e r d e v i c e s s w i t c h i n g a t h i g h e r f r e q u e n c y , t h e r e s u l t i n g c u r r e n t t r a n s i e n t w i l l c a u s e v o l t a g e s p i k e a c r o s s t h e i n t e r c o n n e c t i n g i m p e d a n c e a n d p a r a s i t i c c i r c u i t e l e m e n t s . a s a n e x a m p l e , c o n s i d e r t h e t u r n - o f f t r a n s i t i o n o f t h e p w m m o s f e t . b e f o r e t u r n - o f f c o n d i t i o n , t h e m o s f e t i s c a r r y i n g t h e f u l l l o a d c u r r e n t . d u r i n g t u r n - o f f , c u r r e n t s t o p s f l o w i n g i n t h e m o s f e t a n d i s f r e e w h e e l i n g b y t h e l o w - s i d e m o s f e t a n d p a r a s i t i c d i o d e . a n y p a r a - s i t i c i n d u c t a n c e o f t h e c i r c u i t g e n e r a t e s a l a r g e v o l t a g e s p i k e d u r i n g t h e s w i t c h i n g i n t e r v a l . i n g e n e r a l , u s i n g s h o r t a n d w i d e p r i n t e d c i r c u i t t r a c e s s h o u l d m i n i m i z e i n t e r c o n - n e c t i n g i m p e d a n c e s a n d t h e m a g n i t u d e o f v o l t a g e s p i k e . s i g n a l a n d p o w e r g r o u n d s a r e t o b e k e p t s e p a r a t i n g a n d f i n a l l y c o m b i n e d u s i n g g r o u n d p l a n e c o n s t r u c t i o n o r s i n g l e p o i n t g r o u n d i n g . t h e b e s t t i e - p o i n t b e t w e e n t h e s i g n a l g r o u n d a n d t h e p o w e r g r o u n d i s a t t h e n e g a t i v e s i d e o f t h e o u t p u t c a p a c i t o r o n e a c h c h a n n e l , w h e r e t h e r e i s l e s s n o i s e . n o i s y t r a c e s b e n e a t h t h e i c a r e n o t r e c o m m e n d e d . b e l o w i s a c h e c k l i s t f o r y o u r l a y o u t : c o n d u c t i o n l o s s a n d t r a n s i t i o n l o s s . f o r t h e h i g h - s i d e a n d l o w - s i d e m o s f e t s , t h e l o s s e s a r e a p p r o x i m a t e l y g i v e n b y t h e f o l l o w i n g e q u 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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 2 2 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 ( c o n t . ) k e e p t h e s w i t c h i n g n o d e s ( u g a t e x , l g a t e x , b o o t x , p h a s e x , a n d i s e n x ) a w a y f r o m s e n s i t i v e s m a l l s i g - n a l n o d e s s i n c e t h e s e n o d e s a r e f a s t m o v i n g s i g n a l s . t h e r e f o r e , k e e p t r a c e s t o t h e s e n o d e s a s s h o r t a s p o s s i b l e a n d t h e r e s h o u l d b e n o o t h e r w e a k s i g n a l t r a c e s i n p a r a l l e l w i t h t h e s e s t r a c e s o n a n y l a y e r . t h e s i g n a l s g o i n g t h r o u g h t h e s e s t r a c e s h a v e b o t h h i g h d v / d t a n d h i g h d i / d t , w i t h h i g h p e a k c h a r g i n g a n d d i s c h a r g i n g c u r r e n t . t h e t r a c e s f r o m t h e g a t e d r i v e r s t o t h e m o s f e t s ( u g a t e x a n d l g a t e x ) s h o u l d b e s h o r t a n d w i d e . p l a c e t h e s o u r c e o f t h e h i g h - s i d e m o s f e t a n d t h e d r a i n o f t h e l o w - s i d e m o s f e t a s c l o s e a s p o s s i b l e . m i n i m i z i n g t h e i m p e d a n c e w i t h w i d e l a y o u t p l a n e b e t w e e n t h e t w o p a d s r e d u c e s t h e v o l t a g e b o u n c e o f t h e n o d e . t h e i s e n x t r a c e s h o u l d b e a s e p a r a t e t r a c e , a n d i n d e p e n d e n t l y g o t o t h e d r a i n t e r m i n a l o f t h e l o w - s i d e m o s f e t . t h e c u r r e n t s e n s e r e s i s t o r s h o u l d b e c l o s e t o i s e n x p i n . t h e l o o p f o r m e d b y t h e b o t t o m m o s f e t , o u t p u t i n d u c t o r , a n d o u t p u t c a p a c i t o r , s h o u l d b e v e r y s m a l l . t h e s o u r c e o f t h e b o t t o m m o s f e t s h o u l d t i e t o t h e n e g a t i v e s i d e o f t h e o u t p u t c a p a c i t o r i n o r d e r f o r t h e i s e n x p i n t o g e t t h e v o l t a g e d r o p o n t h e r d s ( o n ) . d e c o u p l i n g c a p a c i t o r , c o m p e n s a t i o n c o m p o n e n t , t h e r e s i s t o r d i v i d e r s , b o o t c a p a c i t o r s , a n d s o f t - s t a r t c a p a c i t o r s s h o u l d b e c l o s e t h e i r p i n s . ( f o r e x a m p l e , p l a c e t h e d e c o u p l i n g c e r a m i c c a p a c i t o r n e a r t h e d r a i n o f t h e h i g h - s i d e m o s f e t a s c l o s e a s p o s s i b l e . t h e b u l k c a p a c i t o r s a r e a l s o p l a c e d n e a r t h e d r a i n ) . 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 n e a r t h e d r a i n o f t h e h i g h - s i d e m o s f e t ; t h e h i g h q u a l i t y c e r a m i c d e c o u p l i n g c a p a c i t o r c a n b e p u t c l o s e t o t h e v c c a n d g n d p i n s ; 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 n e a r t h e l o a d s . t h e i n p u t c a p a c i t o r g n d s h o u l d b e c l o s e t o t h e o u t p u t c a p a c i t o r g n d a n d t h e l o w - s i d e m o s f e t g n d . t h e d r a i n o f t h e m o s f e t s ( v i n a n d p h a s e x n o d e s ) s h o u l d b e a l a r g e p l a n e f o r h e a t s i n k i n g . a n d p h a s e x p i n t r a c e s a r e a l s o t h e r e t u r n p a t h f o r u g a t e x . c o n n e c t t h e s e p i n s t o t h e r e s p e c t i v e c o n v e r t e r ? s h i g h - s i d e m o s f e t s o u r c e . t h e a p w 7 1 0 8 u s e s r i p p l e m o d e c o n t r o l . b u i l d t h e r e s i s t o r d i v i d e r c l o s e t o t h e v s e n x p i n s o t h a t t h e h i g h i m p e d a n c e t r a c e i s s h o r t e r . t h e v s e n x p i n t r a c e s c a n ? t b e c l o s e d t o t h e s w i t c h i n g s i g n a l t r a c e s ( u g a t e x , l g a t e x , b o o t x , p h a s e x , a n d i s e n x ) . t h e p g n d x t r a c e s h o u l d b e a s e p e r a t e t r a c e , a n d i n p e n d e n t l y g o t o t h e s o u r c e o f t h e l o w - s i d e m o s f e t . f o r q f n 4 x 4 - 2 4 p a c k a g e o n l y , t h e t h e r m a l p a d i s t h e p g n d o f t h e d u a l c h a n n e l s . t h e s o u r c e s o f t h e b o t h c h a n n e l s ? l o w - s i d e m o s f e t s s h o u l d b e n e a r t h e p g n d r e s p e c t i v e l y .
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 2 3 p a c k a g e i n f o r m a t i o n s s o p - 2 8 0 l view a 0 . 2 5 seating plane gauge plane c see view a d e 1 e e b a 2 a 1 a h x 4 5 0.10 a1 0.25 0.004 0.010 e1 s y m b o l min. max. 1.75 1.24 0.15 0.25 a a2 c d e e l h millimeters b 0.20 0.30 0.635 bsc ssop-28 0.25 0.50 0.40 1.27 0.025 bsc min. max. inches 0.069 0.049 0.008 0.012 0.006 0.010 0.010 0.020 0.016 0.050 0 3.80 4.00 0.150 0.157 5.80 6.20 0.228 0.244 9.80 10.00 0.386 0.394 0 0 8 8 note : 1. followed from jedec mo-137 af. 2. dimension "d" does not include mold flash, protrusions or gate burrs. mold flash, protrusion or gate burrs shall not exceed 6 mil per side . 3. dimension "e" does not include inter-lead flash or protrusions. inter-lead flash and protrusions shall not exceed 10 mil per side.
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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 2 4 p a c k a g e i n f o r m a t i o n q f n 4 x 4 - 2 4 a b a1 a3 d e pin 1 d2 pin 1 corner e e 2 l k s y m b o l min. max. 1.00 0.00 0.18 0.30 2.50 2.80 0.05 2.50 a a1 b d d2 e e2 e l millimeters a3 0.20 ref qfn4x4-24 0.35 0.45 2.80 0.008 ref min. max. inches 0.039 0.000 0.008 0.012 0.098 0.110 0.098 0.014 0.018 0.80 0.110 0.031 0.002 0.50 bsc 0.020 bsc k 0.20 0.008 3.90 4.10 0.154 0.161 3.90 4.10 0.154 0.161 note : 1. followed from jedec mo-220 wggd-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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 2 5 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 ssop - 28 tape & reel 2500 qfn4x4 - 24 tape & reel 3000 application a h t1 c d d w e1 f 330.0 ? 2.00 50 min. 16.4+2.00 - 0.00 13.0+0.50 - 0.20 1.5 min. 20.2 min. 16.0 ? 0.30 1.75 ? 0.10 7.5 ? 0.10 p 0 p1 p 2 d 0 d1 t a 0 b 0 k 0 ssop - 28 4.0 ? 0.10 8.0 ? 0.10 2.0 ? 0.10 1.5+0.10 - 0.00 1.5 min. 0.6+0.00 - 0.40 6.4 ? 0.20 10.2 ? 0.20 2.1 ? 0.20 application a h t1 c d d w e1 f 330.0 ? 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 qfn4x4 - 24 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 4.30 ? 0.20 4.30 ? 0.20 1.30 ? 0.20 (mm) 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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 2 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 qfn4x4 user direction of feed ssop-28 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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 2 7 test item method description solderability mil - std - 883d - 2003 245 c, 5 sec holt mil - std - 883d - 1005.7 1000 hrs bias @125 c pct jesd - 22 - b, a102 168 hrs, 100%rh, 121 c tst mil - std - 883d - 1011.9 - 65 c~150 c, 200 cycles esd mil - std - 883d - 3015.7 vhbm > 2kv, vmm > 200v latch - up jesd 78 10ms, 1 tr > 100ma r e f l o w c o n d i t i o n ( i r / c o n v e c t i o n o r v p r r e f l o w ) 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 average ramp - up rate (t l to t p ) 3 c/second max. 3 c/second max. preheat - temperature min (tsmin) - temperature max (tsmax) - time (min to max) (ts) 100 c 150 c 60 - 120 seconds 150 c 200 c 60 - 180 seconds time maintained above: - temperature (t l ) - time (t l ) 183 c 60 - 150 seconds 217 c 60 - 150 seconds peak /classification temperature (tp) see table 1 see table 2 time within 5 c of actual peak temperature (tp) 10 - 30 seconds 20 - 40 seconds ramp - down rate 6 c/sec ond max. 6 c/second max. time 25 c to peak temperature 6 minutes max. 8 minutes max. notes: all temperatures refer to topside of the package. measured on the body surface. t 25 c to peak tp ramp-up t l ramp-down ts preheat tsmax tsmin t l t p 25 t e m p e r a t u r e time critical zone t l to t p 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 . 4 - j a n . , 2 0 0 9 a p w 7 1 0 8 w w w . a n p e c . c o m . t w 2 8 table 2. pb - free process ? package classification reflow temperatures package thickness volume mm 3 <350 volume mm 3 350 - 2000 volume mm 3 >2000 <1.6 mm 260 +0 c* 260 +0 c* 260 +0 c* 1.6 mm ? 2.5 mm 260 +0 c* 250 +0 c* 245 +0 c* 3 2.5 mm 250 +0 c* 245 +0 c* 245 +0 c* * tolerance: the device manufacturer/supplier shall assure process compatibility up to and including the stated classification temperature (this means peak reflow temperature +0 c. for example 260 c+0 c) at the rated msl level. 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 table 1. snpb eutectic process ? package peak reflow temperature s package thickness volume mm 3 <350 volume mm 3 3 350 <2.5 mm 240 +0/ - 5 c 225 +0/ - 5 c 3 2.5 mm 225 +0/ - 5 c 225 +0/ - 5 c 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 ( c o n t . )

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