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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 u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 1 a n p e c r e s e r v e s t h e r i g h t t o m a k e c h a n g e s t o i m p r o v e r e l i a b i l i t y o r m a n u f a c t u r a b i l i t y w i t h o u t n o t i c e , a n d a d v i s e c u s t o m e r s t o o b t a i n t h e l a t e s t v e r s i o n o f r e l e v a n t i n f o r m a t i o n t o v e r i f y b e f o r e p l a c i n g o r d e r s . 1 x / 1 . 5 x / 2 x c h a r g e p u m p w h i t e l e d d r i v e r f e a t u r e s 1 . 5 % led current matching high efficiency up to 90% over li-ion battery discharge output current up to 30ma per led 2.7v to 5.5v operating voltage allow to turn on or off a combination of leds 1x/1.5x/2x charge pump modes low shutdown current: 2 m a maximum low input ripple and emi internal soft-start limits inrush current short circuit current-limit thermal shutdown protection output over-voltage protection 3mmx3mm 16-pin qfn (qfn3x3-16) package lead free and green devices available (rohs compliant) a p p l i c a t i o n s g e n e r a l d e s c r i p t i o n the APW7008 is a high efficiency charge pump white led driver; the device drives up four white leds with regulated constant current for uniform intensity. the sup- ply voltage ranges from 2.7v to 5.5v and it is optimized for a li-ion battery application. the APW7008 operates in 1x, 1.5x, and 2x charge pump modes and automatically switches the charge pump modes depend on the input voltage to maintain the required power for high power efficiency. the APW7008 provides up to 30ma per led for a total of 120ma and allows several methods, such as a pwm signal on the ctrl0 pin for led dimming. three control logic pins allow to disable or enable a combina- tion of leds. the supply current is only 2ma in 2x mode, and the en pin allows the device to enter shutdown mode with 2 m a quiescent current. the APW7008 switches at 1mhz frequency and only requires four 1 m f ceramic ca- pacitors and one resistor, and ensures low input current ripple and emi. the APW7008 is available in a 16-pin qfn package. cellular phone white led back light portable device pda and handheld computer dsc p i n c o n f i g u r a t i o n APW7008 qfn3x3-16 top view 1 3 2 4 6 5 7 8 i l e d 2 i l e d 1 ctrl1 ctrl0 en i s e t ctrl2 v o u t i l e d 3 i l e d 4 c1+ c1- gnd c 2 + c2- v i n 12 10 11 9 15 16 14 13 metal gnd pad (bottom)
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 u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 2 o r d e r i n g a n d m a r k i n g i n f o r m a t i o n n o t e : a n p e c l e a d - f r e e p r o d u c t s c o n t a i n m o l d i n g c o m p o u n d s / d i e a t t a c h m a t e r i a l s a n d 1 0 0 % m a t t e t i n p l a t e t e r m i n a t i o n f i n i s h ; w h i c h a r e f u l l y c o m p l i a n t w i t h r o h s . a n p e c l e a d - f r e e p r o d u c t s m e e t o r e x c e e d t h e l e a d - f r e e r e q u i r e m e n t s o f i p c / j e d e c j - s t d - 0 2 0 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 ) . symbol parameter rating unit v out vout to gnd - 0.3 to +6 v v in vin to gnd - 0.3 to +6 v v c1+ , v c1 - , v c2+ , v c2 - c1+, c1 - , c2+, c2 - to gnd - 0.3 to +6 v v iled1 - 4 iled1 - 4 to gnd - 0.3 to +6 v v ctrl0/1/2 , v en ctrl0/1/2, en to gnd - 0.3 to +6 v v iset iset to gnd - 0.3 to 2 v t j maximum junction temperature +150 c t stg storage temperature - 65 ~ 150 c t sdr maximum lead soldering temperature, 10 seconds 260 c a b s o l u t e m a x i m u m r a t i n g s ( n o t e 1 , 2 ) n o t e 1 : s t r e s s e s b e y o n d t h e a b s o l u t e m a x i m u m r a t i n g m a y d a m a g e t h e d e v i c e a n d o p e r a t i n g i n t h e a b s o l u t e m a x i m u m r a t i n g c o n d i t i o n s f o r e x t e n d e d p e r i o d s m a y a f f e c t d e v i c e r e l i a b i l i t y . n o t e 2 : t h e m a x i m u m a l l o w a b l e p o w e r d i s s i p a t i o n a t a n y t a ( a m b i e n t t e m p e r a t u r e ) i s c a l c u l a t e d u s i n g : p d ( m a x ) = ( t j ? t a ) / q j a ; t j = 1 2 5 c . e x c e e d i n g t h e m a x i m u m a l l o w a b l e p o w e r d i s s i p a t i o n w i l l r e s u l t i n e x c e s s i v e d i e t e m p e r a t u r e . 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 r q ja thermal resistance - junction to ambient qfn3x3 - 16 40 c/w APW7008 handling code temperature range package code package code qa : qfn3x3-16 operating ambient temperature range i : -40 to 85 o c handling code tr : tape & reel assembly material g : halogen and lead free device assembly material APW7008 qa : apw 7008 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 . 4 - j u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 3 r e c o m m e n d e d o p e r a t i n g c o n d i t i o n s symbol parameter rating unit v in input voltage 2.8 to 4.5 v v out output voltage 3 to 4 v i led led current 5 to 30 ma output current, v in >3.5v, v f =3.1v, 1x mode 180 output current, 3.5v3.1v, v f =3.1v, 1.5x mode 120 i out output current, 3.1v 2.8v, v f =3.1v, 2x mode 90 ma t a ambient temperature - 40 to 85 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 apw70 0 8 symbol parameter test conditions min. typ. max. unit v in input voltage 2.7 - 5.5 v v uvlo under - voltage lockout threshold v in falling 2.2 2.4 2.6 v under - voltage lockout hysteresis - 50 - mv in 1.5x/2x mode - 2 4 ma no switching in 1x mode - 0.5 1 ma i q quiescent current en=0 - 0.1 2 m a i led - err led current accuracy 5 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 u n . , 2 0 0 9 a p w 7 0 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 . ) apw70 0 8 symbol parameter test conditions min. typ. max. unit v il logic pins low threshold - 0.6 0.3 v i ih logic pins high current v ih = vin - - 1 m a i il logic pins low current v il = gnd - - 1 m a thermal shutdown - 150 - c thermal shutdown h ysteresis - 20 - c v in = 2.85 to 5.5v, c in = c out = c1 = c2 = 1 m f (esr = 0.03 w ), i led = 20ma, t a = -40c to +85c, unless otherwise noted. typical values are at t a = +25c. note 3: led current accuracy is defined as: ( i l e d - m e a s u r e d - i l e d - s e t ) / i l e d - s e t n o t e 4 : l e d c u r r e n t m a t c h i n g i s d e f i n e d a s : ( i l e d - m a x - i l e d - m i n ) / ( i l e d - m a x + i l e d - m i 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 u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 5 20 30 40 50 60 70 80 90 100 2.5 3 3.5 4 4.5 4 leds at 15ma vf=3.3v 20 30 40 50 60 70 80 90 100 2.5 3 3.5 4 4.5 4 leds at 20ma vf=3.3v 20 30 40 50 60 70 80 90 100 2.5 3 3.5 4 4.5 4 leds at 15ma vf=3.1v 20 30 40 50 60 70 80 90 100 2.5 3 3.5 4 4.5 4 leds at 20ma vf=3.1v 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 i n p u t v o l t a g e ( v ) e f f i c i e n c y v s . i n p u t v o l t a g e efficiency (%) e f f i c i e n c y v s . i n p u t v o l t a g e i n p u t v o l t a g e ( v ) efficiency (%) e f f i c i e n c y v s . i n p u t v o l t a g e i n p u t v o l t a g e ( v ) efficiency (%) i n p u t v o l t a g e ( v ) efficiency (%) e f f i c i e n c y v s . i n p u t v o l t a g e 20 1 5
c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 4 - j u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 6 25 26 27 28 29 30 31 32 2.5 3 3.5 4 4.5 5 5.5 4 leds at 30ma 16 17 18 19 20 21 2.5 3 3.5 4 4.5 5 5.5 4 leds at 20ma 60 80 100 120 140 160 180 200 2.5 3 3.5 4 4.5 5 4 leds at 20ma 100 120 140 160 180 200 220 240 260 2.5 3 3.5 4 4.5 5 4 leds at 30ma 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 . ) i n p u t v o l t a g e ( v ) i n p u t c u r r e n t v s . i n p u t v o l t a g e input current (ma) i n p u t c u r r e n t v s . i n p u t v o l t a g e i n p u t v o l t a g e ( v ) input current (ma) l e d c u r r e n t v s . i n p u t v o l t a g e i n p u t v o l t a g e ( v ) led current (ma) i n p u t v o l t a g e ( v ) led current (ma) l e d c u r r e n t v s . i n p u t v o l t a g e
c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 4 - j u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 7 500 600 700 800 900 1000 1100 1200 -40 -20 0 20 40 60 80 100 120 140 in 2x mode vin=4v 800 850 900 950 1000 1050 1100 1150 1200 2.5 3 3.5 4 4.5 in 2x mode iled=20ma 17 18 19 20 21 -40 -20 0 20 40 60 80 100 120 140 4 leds at 20ma vin=4v 0.7 0.8 0.9 1 1.1 1.2 2.5 3 3.5 4 4.5 5 5.5 high threshold low threshold 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 . ) i n p u t v o l t a g e ( v ) l o g i c t h r e s h o l d v o l t a g e v s . i n p u t v o l t a g e logic threshold voltage(v) s w i t c h i n g f r e q u e n c y v s . i n p u t v o l t a g e i n p u t v o l t a g e ( v ) switching frequency (khz) s w i t c h i n g f r e q u e n c y v s . t e m p e r a t u r e t e m p e r a t u r e ( c ) switching frequency (khz) t e m p e r a t u r e ( c ) led current (ma) l e d c u r r e n t v s . t e m p e r a t u r 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 . 4 - j u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 8 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 3 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4 leds at 20ma vf=3.3v 200 250 300 350 400 -40 -20 0 20 40 60 80 100 120 140 in 1x mode vin=4v 17 18 19 20 21 22 -40 -20 0 20 40 60 80 100 120 140 4 leds at 20ma vin=2.7v 17 18 19 20 21 22 -40 -20 0 20 40 60 80 100 120 140 4 leds at 20ma vin=3.3v 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 . ) t e m p e r a t u r e ( c ) l e d c u r r e n t v s . t e m p e r a t u r e led current (ma) l e d c u r r e n t v s . t e m p e r a t u r e t e m p e r a t u r e ( c ) led current (ma) q u i e s c e n t c u r r e n t v s . t e m p e r a t u r e t e m p e r a t u r e ( c ) quiescent current (ma) i n p u t v o l t a g e ( v ) quiescent current (ma) q u i e s c e n t c u r r e n t v s . i n p u t v o l t a g e
c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 4 - j u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 9 v out (1v/div) ctrl0 (2v/div) i led (10ma/div) 4 leds at 20ma vf=3.1v, vin=4v f=200hz i in (100ma/div) v out (2v/div) en (5v/div) i led (10ma/div) 4 leds at 20ma vf=3.1v, vin=2.7v i in (100ma/div) v out (2v/div) en (5v/div) i led (10ma/div) 4 leds at 20ma vf=3.1v, vin=3.3v i in (100ma/div) v out (2v/div) en (5v/div) i led (10ma/div) 4 leds at 20ma vf=3.1v, vin=4v t y p i c a l o p e a t i n g c h a r a c t e r i s t i c s ( c o n t . ) t i m e ( 0 . 1 m s / d i v ) s t a r t u p i n 1 x m o d e s t a r t u p i n 1 . 5 x m o d e t i m e ( 0 . 1 m s / d i v ) s t a r t u p i n 2 x m o d e t i m e ( 0 . 1 m s / d i v ) t i m e ( 2 m s / d i v ) d i m m i n g i n 1 x m o d e
c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 4 - j u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 1 0 v out (1v/div) v in (1v/div) i led (20ma/div) 4 leds at 20ma, vf=3.1v vin=3.2v to 3.8v v out (1v/div) v in (1v/div) i led (10ma/div) 4 leds at 20ma vf=3.1v, vin=4v led1 is open v out (1v/div) ctrl0 (1v/div) i led (10ma/div) 4 leds at 20ma, vf=3.1v, vin=2.7v, f=200hz v out (1v/div) ctrl0 (1v/div) i led (10ma/div) 4 leds at 20ma, vf=3.1v vin=3.3v, f=200hz 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 . ) t i m e ( 2 m s / d i v ) d i m m i n g i n 1 . 5 x m o d e d i m m i n g i n 2 x m o d e t i m e ( 2 m s / d i v ) o v p e v e n w i t h l e d o p e n c i r c u i t t i m e ( 0 . 2 m s / d i v ) t i m e ( 0 . 1 m s / d i v ) l i n e t r a n s i e n t r e s p o n s e i n 1 x t o 1 . 5 x m o d e
c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 4 - j u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 1 1 v out (1v/div) v in (1v/div) i led (20ma/div) 4 leds at 20ma, vf=3.1v vin=2.8v to 3.4v 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 . ) t i m e ( 0 . 1 m s / d i v ) l i n e t r a n s i e n t r e s p o n s e i n 1 . 5 x t o 2 x m o d e p i n d e s c r i p t i o n pin no. name function 1 en enable input pin. the en pin is an active high control. pull en pin above 1.3v to enable the device; pull en pin below 0.3v to disable the device. 2 ctrl0 3 ctrl1 4 ctrl2 led on/off control pin. allow disabling or enabling a combination of l eds. 5 iset led current set input. connect a resistor from iset to gnd to set the led current. viset is typically 1.2v. 6 vout output voltage pin. connect vout to the led anode. connect a 1 m f capacitor from vout to gnd. 7 vin supply voltage input pin. connect a 1 m f capacitor from vin to gnd. 8 c2+ bucket capacitor1 positive terminal. connect a 1 m f capacitor from c2+ to c2 - . 9 c2 - bucket capacitor1 negative terminal. connect a 1 m f capacito r from c2+ to c2 - . 10 c1+ bucket capacitor1 positive terminal. connect a 1 m f capacitor from c1+ to c1 - . 11 c1 - bucket capacitor1 negative terminal. connect a 1 m f capacitor from c1+ to c1 - . 12 gnd device ground pin. 13 iled4 14 iled3 15 iled2 16 iled1 leds cathode connection. the led current flows from vout through led into iled_ pin. the charge pump regulates the lowest viled to 180mv. connect iled_ pin to vout if the led is not used.
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 u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 1 2 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 APW7008 c i n 1 m f c 2 1 m f c2+ vin vout iset iled4 iled3 iled2 iled1 c2- c1+ c1- gnd ctrl2 ctrl1 ctrl0 en c 1 1 m f battery digital inputs r set 4 3 2 1 5 6 7 8 9 10 11 12 16 15 14 13 c out 1 m f b l o c k d i a g r a m error amp 1x/1.5x/2x mode charge pump and gate control logic + - + - + - + - + - 1.2v controlled current mirror mode select and min iled select iset ctrl1 ctrl0 vin gnd c1+ c1- c2+ c2- vout iled1 iled2 iled3 iled4 current limit + - + - 0.1v por & soft-start 1mhz oscillator en ctrl2 led on/off control + - 0.18v + - 1.2v
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 u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 1 3 f u n c t i o n d e s c r i p t i o n soft-start the APW7008 provides the soft-start function to limit the inrush current during start-up. when the input voltage is supplied to the device and exceeds the uvlo voltage, the output capacitor is charged directly from input with a limited current source. approximate 100 m s after the out- put voltage approaches the input voltage, the device starts to provide the programmed led current and determines which of 1x and 1.5x, or 2x mode is required. when the programmed led current can be reached with 1x mode, the soft-start is completed and the device operates in 1x mode. when the programmed led current cannot be reached, the charge pump goes into 1.5x mode. if the 1.5x mode charge pump cannot suffice for the led cur- rent need, the charge pump will switch to 2x mode. mode transition the APW7008 operates in 1x, 1.5x, and 2x charge pump modes and automatically switches the charge pump modes depend on the input voltage to maintain the re- quired power for high power efficiency. if the APW7008 operates in 1x mode, the vout is pulled up to the vin. when the vin decreases, the viled will decease to main- tain the regulated led current. until the viled is below 100mv, the device will switch to 1.5x mode. in 1.5x mode, the viled is regulated to 0.18v, and the output voltage is vf+0.18v. if the vin continues to decrease until the viled is below 100mv again, the device will switch to 2x mode. when the vin rises and reaches by approximately vout - 300mv, the apw700 8 switches back to 1.5x mode. if the vin continues to rise and reach by approxi mately vout+300mv, the APW7008 switches back to 1x mode. the 2x charge pump is enough to suffice the white led for a li-ion battery application. the APW7008 ensures that in the 1x mode for as long as possible to increase the efficiency and extend the operating range by using the 2x mode. the transition voltages from 1x to 1.5x and 1.5x to 2x are given by: control logic pins t h e a p w 7 0 0 8 p r o v i d e s t h r e e l o g i c i n p u t p i n s t o e n - a b l e o r d i s a b l e a c o m b i n a t i o n o f l e d s . t a b l e 1 s h o w s t h e t r u t h t a b l e o f t h e l o g i c p i n s . i f t h e l e d c h a n n e l s a r e n o t u s e d , c o n n e c t i n g t h e i l e d p i n s t o v o u t t o t u r n o f f t h e r e s p e c t i v e l e d c h a n n e l s . control logic pin led status ctrl2 ctrl1 ctrl0 led4 led3 led2 led1 0 0 0 off off off on 0 0 1 off off on off 0 1 0 off on off off 0 1 1 on off off off 1 0 0 off off on on 1 0 1 off on on on 1 1 0 on on on on 1 1 1 off off off off table 1. the truth table of control logic pins l e d c u r r e n t s e t t i n g connect a resistor from iset pin to gnd to set the led current. the iset voltage is typically 1.2v, the led cur- rent is typically 400 times the current through the iset resistor. the led current is given by: w h e r e v f i s t h e f o r w a r d v o l t a g e o f l e d i o u t i s t h e o u t p u t c u r r e n t r o u t 1 x i s t h e o u t p u t i m p e d a n c e i n 1 x m o d e = 1 . 6 w r o u t 1 . 5 x i s t h e o u t p u t i m p e d a n c e i n 1 . 5 x m o d e = 7 w t h e a p w 7 0 0 8 p r o v i d e s u p 3 0 m a o f l e d c u r r e n t p e r l e d a n d t h e d e v i c e h a s a m a x c u r r e n t m a t c h i n g o f 5 % b e t w e e n a n y t w o l e d c u r r e n t s a n d a m a x c u r r e n t a c c u - r a c y o f 8 % . i f h i g h a c c u r a c y i s r e q u i r e d , u s i n g a 1 % p r e c i s i o n s u r f a c e m o u n t r e s i s t o r f o r t h e n e e d . iled (ma) rset (k w ) 5 92 10 47 15 32 20 24 30 16.5 v t r a n s 1 x = v f + 0 . 1 v + ( i o u t x r o u t 1 x ) vtrans1.5x = [vf + 0.1v + (iout x rout1.5x)] / 1.5 table 2. rset value selection led set i v 2 . 1 400 r =
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 u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 1 4 f u n c t i o n d e s c r i p t i o n ( c o n t . ) shutdown/enable pull the en above 1.3v to enable the device and pull en pin below 0.3v to disable the device. in shutdown mode, l e d c u r r e n t s e t t i n g ( c o n t . ) if any of leds is failed or unused led channel is not connected to vout, the charge pump mode will go in to 2x mode and the output voltage will be pumped to 2 times the input voltage . if the output voltage is over 5.5v, the over-voltage protection circuit will limit t he out- put voltage to approximately 5.5v. f i g u r e 1 . r s e t v a l u e v s . l e d c u r r e n t 0 50 100 150 200 250 300 350 400 0 5 10 15 20 25 30 iled (ma) rset (ohm) over-voltage protection all inter nal control circuit s are turned off and the qui- escent current is below 2 m a. when the device exits shut- down mode, the output has soft-start function as the in- put voltage startup.
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 u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 1 5 a p p l i c a t i o n i n f o r m a t i o n where: i led(max) is programmed led current by iset pin toff is the off time of the pwm signal ton is the on time of the pwm signal ctrl2 ctrl1 ctrl0 en vin 4 3 2 1 APW7008 off on pwm 0 2 4 6 8 10 12 14 16 18 20 0 10 20 30 40 50 60 70 80 90 100 dimming duty (%) led current (ma) f=40khz f=100hz led=20ma vin=2.7v, 2x mode f=50khz f=10khz figure 3. pwm dimming frequency vs. led current figure 2. pwm dimming application circuit 1. pwm dimming using ctrl0, ctrl1, ctrl2 the first method for dimming the leds is to apply a pwm signal into the ctrl0, ctrl1, and ctrl2 pins. figure 2 shows the application circuit. the average led current is proportional to the pwm signal duty cycle. note that the frequency of pwm signal will affect the minimum dim- ming duty. figure 3 shows the led current vs. dimming frequency and dimming duty, the recommend dimming frequency is below 10khz. the average led current is calculated by the following equation: b r i g h t n e s s c o n t r o l c a p a c i t o r s e l e c t i o n f o r l o w e r i n p u t a n d o u t p u t v o l t a g e r i p p l e s , b o t h i n p u t a n d o u t p u t c a p a c i t o r s s h o u l d b e l a r g e r v a l u e s a n d l o w e r e s r c a p a c i t o r s . h o w e v e r , t h e l a r g e r o u t p u t c a p a c i t o r v a l u e s w i l l i n c r e a s e t h e s o f t - s t a r t t i m e . t h e l o w e r c h a r g e p u m p f l y i n g c a p a c i t o r s v a l u e s a n d e s r i m p r o v e t h e e f f i c i e n c y , b u t l o w e r c a p a c i t o r v a l u e s m a y l i m i t t h e l e d ? s c u r r e n t s a t l o w i n p u t v o l t a g e . i t i s r e c o m m e n d e d t h a t t h e l o w e s r a n d l o w v a r i a t i o n o v e r t e m p e r a t u r e , s u c h a s t h e c e r a m i c c a p a c i t o r s w i t h x 7 r o r x 5 r a n d t h e v a l u e i s 1 m f f o r t h e i n p u t c a p a c i t o r , o u t - p u t c a p a c i t o r , a n d t h e c h a r g e p u m p f l y i n g c a p a c i t o r s . 2 . a n a l o g d i m m i n g w i t h a n a l o g v o l t a g e t h e s e c o n d m e t h o d f o r d i m m i n g t h e l e d s i s t o a p p l y a v o l t a g e t h r o u g h a r e s i s t o r i n t o t h e i s e t p i n . t h e v a r i a t i o n o f l e d c u r r e n t i s p r o p o r t i o n a l t o t h e v a r i a t i o n o f t h e a n a - l o g v o l t a g e . i f t h e r e s i s t o r v a l u e s a r e c h o s e n c o r r e c t l y , t h e a n a l o g c o n t r o l v o l t a g e v a r i e s t h e o u t p u t c u r r e n t f r o m 0 m a t o f u l l l e d c u r r e n t . f i g u r e 4 s h o w s t h e a p p l i c a t i o n c i r c u i t . s e e t h e t a b l e 2 a n d c h o o s e t h e r e q u i r e d m a x i m u m l e d c u r r e n t a n d t h e c o r r e s p o n s i v e r s e t v a l u e , u s i n g t h e b e - l o w e q u a t i o n t o c a l c u l a t e t h e v a l u e s o f r 1 a n d r 2 , n o t e t h a t t h e v a d j w i l l n e e d t o b e g r e a t e r t h a n 1 . 2 v . w h e r e : v i s e t = 1 . 2 v v a d j = t h e a n a l o g v o l t a g e f o r d i m m i n g t h e l e d s r s e t = t h e e q u i v a l e n t r s e t r e s i s t a n c e ( s e e t a b l e 2 ) . iset r1 5 APW7008 v adj r2 figure 4. analog voltage dimming application circuit toff ton i toff i (max) led ) avg ( led + = set adj iset adj adj r v 2 r ) v v ( 1 r 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 u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 1 6 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 . ) 3. digital dimming with external nmos transistors the third method for dimming the leds is to change the equivalent resistance for rset with the external nmos transistors. the equivalent resistance is the parallel combinations of the r1, r2, r3, and r4. r4 is always connected and selected for the minimum led current. figure 5 shows the application circuit. figure 5. digital dimming application circuit b r i g h t n e s s c o n t r o l ( c o n t . ) iset 5 APW7008 r1 r2 r4 r3 4 . p w m d i m m i n g w i t h e n p i n a n o t h e r m e t h o d f o r d i m m i n g t h e l e d s i s t o a p p l y a p w m s i g n a l i n t o t h e e n p i n . t h e a v e r a g e l e d c u r r e n t i s p r o p o r t i o n a l t o t h e p w m s i g n a l d u t y c y c l e . n o t e t h a t t h e f r e q u e n c y o f p w m s i g n a l w i l l a f f e c t t h e m i n i - m u m d i m m i n g d u t y . t h e r e c o m m e n d d i m m i n g f r e - q u e n c y i s b e t w e e n 1 0 0 h z a n d 1 k h z . t h e a v e r a g e l e d c u r r e n t i s c a l c u l a t e d b y t h e f o l l o w i n g e q u a t i o n : w h e r e : i l e d ( m a x ) i s p r o g r a m m e d l e d c u r r e n t b y i s e t p i n t o f f i s t h e o f f t i m e o f t h e p w m s i g n a l t o n i s t h e o n t i m e o f t h e p w m s i g n a l layout consideration the apw700 8 is a high frequency charge pump for white led driver and requires some care when laying out the printed circuit board. the metal gnd pad of the bottom of the package must be soldered to the pcb and con- nected to the gnd plane on the backside through sev- eral thermal vias. place the cin, cout, c1, and c2 as close to ic as possible for reducing the switching noise. toff ton i ton i (max) led ) avg ( led + =
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 u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 1 7 p a c k a g e i n f o r m a t i o n q f n 3 x 3 - 1 6 d e pin 1 a1 a3 a b pin 1 corner e 2 l d2 e k s y m b o l min. max. 1.00 0.00 0.18 0.30 1.50 1.80 0.05 1.50 a a1 b d d2 e e2 e l millimeters a3 0.20 ref qfn3x3-16 0.30 0.50 1.80 0.008 ref min. max. inches 0.039 0.000 0.007 0.012 0.059 0.071 0.059 0.012 0.020 0.020 bsc k 0.20 0.008 2.90 3.10 0.114 0.122 2.90 3.10 0.114 0.122 0.80 0.071 0.031 0.002 0.50 bsc note : 1. followed from jedec mo-220 weed-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 u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 1 8 application a h t1 c d d w e1 f 178 ? 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 qfn3x3 - 16 4.0 ? 0.10 4.0 ? 0.10 2.0 ? 0.05 1.5+0.10 - 0.00 1.5 min. 0.6+0.00 - 0. 40 3.30 ? 0.20 3.30 ? 0.20 1.30 ? 0.20 c a r r i e r t a p e & r e e l d i m e n s i o n s d e v i c e s p e r u n i t ( m m ) package type unit quantity qfn3x3 - 16 tape & reel 3000 a e 1 a b w f t p0 od0 b a0 p2 k0 b 0 section b-b section a-a od1 p1 h t1 a d
c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 4 - j u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 1 9 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 qfn3x3-16 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 . 4 - j u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 2 0 c l a s s i f i c a t i o n r e f l o w p r o f i l e s profile feature sn - pb eutectic assembly pb - free assembly preheat & soak temperature min (t smin ) temperature max (t smax ) time (t smin to t smax ) ( t s ) 100 c 150 c 60 - 120 seconds 150 c 200 c 60 - 1 2 0 seconds average ramp - up rate (t smax to t p ) 3 c/second ma x. 3 c/second max. liquidous temperature ( t l ) time at l iquidous (t l ) 183 c 60 - 150 seconds 217 c 60 - 150 seconds peak package body temperature (t p ) * see classification temp in table 1 see classification temp in table 2 time (t p ) ** within 5 c of the spec ified c lassification t emperature ( t c ) 2 0 ** seconds 3 0 ** seconds average r amp - down rate (t p to t smax ) 6 c/second max. 6 c/second max. time 25 c to p eak t emperature 6 minutes max. 8 minutes max. * tolerance for peak profile temperature (t p ) is defined a s a supplier minimum and a user maximum. ** tolerance for time at peak profile temperature (t p ) is defined as a supplier minimum and a user maximum. table 2. pb - free process ? classification temperatures (tc) package thickness volume mm 3 <350 volume mm 3 350 - 2000 volume mm 3 >2000 <1.6 mm 260 c 260 c 260 c 1.6 mm ? 2.5 mm 260 c 250 c 245 c 3 2.5 mm 250 c 245 c 245 c table 1. snpb eutectic process ? classification temperatures (tc) package thickness volume mm 3 <350 volume mm 3 3 350 <2.5 mm 235 c 22 0 c 3 2.5 mm 220 c 220 c test item method description solderability jesd - 22, b102 5 sec, 245 c holt jesd - 22, a108 1000 hrs, bias @ 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, a115 vmm ? 200v latch - up jesd 78 10ms, 1 tr ? 100ma r e l i a b i l i t y t e s t p r o g r a m
c o p y r i g h t ? a n p e c e l e c t r o n i c s c o r p . r e v . a . 4 - j u n . , 2 0 0 9 a p w 7 0 0 8 w w w . a n p e c . c o m . t w 2 1 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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