typical application circuit pam2808 5w high power hbled driver 1 www.poweranalog.com 08/2011 rev1.0 , power analog microelectronics inc features n high output current up to 1.5a standard sop-8(ep) packages pb-free package high bright led driver white led torch (flashlight) the pam2808 is a 5w high power hbled driver with 1.5a constant current. it features high efficiency and low quiescent current,making it ideal for battery powered applications. the pam2808 features over current protection and over temperature shutdown. the pam2808 is stable with a ceramic output capacitor of 4.7 f or higher. pam2808 is available in sop-8(ep) package. n n n n n n n n low feedback voltage:0.1v stable with a ceramic output capacitor low quiescent current open load led protection over temperature shutdown low temperature coefficient applications general description n n vin vout vin vout gnd en fb pam2808 rs c 4.7 f in c o 4.7 f
block diagram pin configuration & marking information 2 www.poweranalog.com , power analog microelectronics inc 08/2011 rev1.0 top view sop-8(ep) v voltage code : y year : w week : x internal code : pam2808 5w high power hbled driver nc 1 2 3 4 5 6 7 8 vin en gnd nc fb vout nc overcurrent shutdown thermal shutdown amp vin en vout reference gnd fb
absolute maximum ratings these are stress ratings only and functional operation is not implied exposure to absolute maximum ratings for prolonged time periods may affect device reliability all voltages are with respect to ground . . . recommended operating conditions thermal information 3 www.poweranalog.com , power analog microelectronics inc input voltage...............................................6.5v maximum output current......................p /(v -v ) storage temperature 65 to 150 maximum junction temperature 150 en, fb, vout pin voltage .................................................-0.3v to v +0.3v ....................- .................. lead soldering temperature (5sec)........... 300 in d in o c c c c maximum supply voltage..............................6v junction temperature range........-40 to 125 c c ambient temperature range...........-40 c to 85 c 08/2011 rev1.0 p a r a m e t e r s y m b o l p a c k a g e m a x i m u m u n i t t h e r m a l r e s i s t a n c e ( j u n c t i o n t o c a s e ) j c s o p - 8 ( e p ) 1 1 c / w t h e r m a l r e s i s t a n c e ( j u n c t i o n t o a m b i e n t ) j a s o p - 8 ( e p ) 9 0 c / w pam2808 5w high power hbled driver
electrical characteristic 4 www.poweranalog.com , power analog microelectronics inc v =4.5v,t =25c, c =4.7 f, c =4.7 f, unless otherwise noted. in a in o 08/2011 rev1.0 p a r a m e t e r s y m b o l t e s t c o n d i t i o n s m i n t y p m a x u n i t s i n p u t v o l t a g e v i n 2 . 5 6 . 0 v f b r e f e r e n c e v o l t a g e v r e f 0 . 1 v r s = 0 . 3 3 3 0 r s = 0 . 1 4 7 0 0 r s = 0 . 1 1 0 0 0 o u t p u t c u r r e n t i o r s = 0 . 0 6 7 1 5 0 0 m a o v e r t e m p e r a t u r e s h u t d o w n o t s 1 5 0 o c o v e r t e m p e r a t u r e h y s t e r e s i s o t h 4 0 o c e n i n p u t h i g h t h r e s h o l d v e h v i n = 2 . 5 v t o 5 v 1 . 5 v e n i n p u t l o w t h r e s h o l d v e l v i n = 2 . 5 v t o 5 v 0 . 3 v s h u t d o w n c u r r e n t i s d v e n = 0 v 1 a pam2808 5w high power hbled driver
5 www.poweranalog.com , power analog microelectronics inc typical performance characteristics t =25c,c =4.7 f,co=4.7 f,unless otherwise noted. a in 08/2011 rev1.0 pam2808 5w high power hbled driver 1. led current vs input voltage 2. feedback voltage vs input voltage 3. dropout voltage vs led current 0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0 3 . 0 3 . 5 4 . 0 4 . 5 5 . 0 5 . 5 6 . 0 i n p u t v o l t a g e ( v ) 1 w 2 w 3 w 5 w 0 2 0 4 0 6 0 8 0 1 0 0 1 2 0 3 . 0 3 . 5 4 . 0 4 . 5 5 . 0 5 . 5 6 . 0 i n p u t v o l t a g e ( v ) 1 w 2 w 3 w 5 w 0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0 0 5 0 0 1 0 0 0 1 5 0 0 2 0 0 0 l e d c u r r e n t ( m a ) 4. start up
6 www.poweranalog.com , power analog microelectronics inc external capacitor requirements regulator protection thermal information a 4.7f or larger ceramic input bypass capacitor, connected between v and gnd and located close to the pam2808, is required for stability. a 4.7 f minimum value capacitor from v to gnd is also required. to improve transient response, noise rejection, and ripple rejection, an additional 1 0 f o r l a r g e r , l o w e s r c a p a c i t o r i s recommended at the output. a higher-value, low esr output capacitor may be necessary if large, fast-rise-time load transients are anticipated and the device is located several i nches from the power source, especially if the minimum input voltage of 2.5 v is used. the pam2808 features internal current limiting, thermal protection and short circuit protection. during normal operation, the pam2808 limits output current to about 2.5a. when current limiting engages, the output voltage scales back linearly until the over current condition ends. while current limiting is designed to prevent gross device failure, care should be taken not to exceed the power dissipation ratings of the package. if the temperature of the device exceeds 150c, thermal-protection circuitry will shut down. once the device has cooled down to approximately 40c below the high temp trip point, regulator operation resumes. the amount of heat generates is: p =(v -v )i . all integrated circuits have a maximum allowable junction temperature (t max) above which normal operation is not assured. a system designer must design the operating environment so that the operating junction temperature (t ) d o e s n o t e x c e e d t h e m a x i m u m j u n c t i o n t e m p e r a t u r e ( t m a x ) . t h e t w o m a i n environmental variables that a designer can use to improve thermal performance are air flow and e x t e r n a l h e a t s i n k s . t h e p u r p o s e o f t h i s information is to aid the designer in determining the proper operating environment for a linear regulator that is operating at a specific power level. in ge ne r al , t he m a x im um ex p ec t ed po we r (p (max)) consumed by a linear regulator is computed as: where: v is the average input voltage. v is the average output voltage. i is the average output current. i is the quiescent current. the quiescent current is insignificant compared to the average output current; therefore, the term v xi can be neglected. the operating junction temperature is computed by adding the ambient temperature (t ) and the increase in temperature due to the regulator' s power dissipation. the temperature rise is computed by multiplying the maximum expe cted power dissipation by the sum of the thermal resistances between the junction and the case r ), the case to heatsink (r ), and the heatsink to ambient (r ). thermal resistances are measures of how effectively an object dissipates heat. typically, the larger the device, the more surface area available for power dissipation so that the object?s thermal resistance will be lower. in o d in o o j j j d i (avg) o(avg) o(avg) (q) i(avg) (q) a jc cs sa ( l l l l application information ( ) ( ) ( ) ( ) ( ) ( ) d m a x i a v g o a v g o a v g i a v g q p = v - v i + v i 08/2011 rev1.0 pam2808 5w high power hbled driver
ordering information 7 www.poweranalog.com , power analog microelectronics inc output voltage number of pins pam2808 x x x xxx x shipping package package type pin configuration 08/2011 rev1.0 p i n c o n f i g u r a t i o n p a c k a g e t y p e n u m b e r o f p i n s s h i p p i n g p a c k a g e b t y p e : 1 . n c 2 . v i n 3 . e n 4 . g n d 5 . n c 6 . f b 7 . v o u t 8 . n c l : s o p - 8 ( e p ) b : 8 r : t a p e & r e e l p a r t n u m b e r m a r k i n g p a c k a g e t y p e m o q & s h i p p i n g p c k a g e p a m 2 8 0 8 b l b r p 2 8 0 8 x x x y w s o p - 8 ( e p ) 2 , 5 0 0 u n i t s / t a p e s & r e e l pam2808 5w high power hbled driver
outline dimensions 8 www.poweranalog.com , power analog microelectronics inc 08/2011 rev1.0 sop-8(ep) pam2808 5w high power hbled driver
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