power&rf 4-18 2005 winter white led flash driver ic ? led ??? ic tk11891f description the tk11891f is a step-up dc-dc converter designed for camera flash of the mobile phone. tk11891f can drive two, hree or four leds in series. the tk11891f can also be used i n other applications as a step-up dc-dc converter. tk11891f ?e? led ??? _k pwm ?NR dc-dc ` ic ?? ??A? 2 4 ?? led ???? ??NR dc-dc `?????? features ? operating voltage range 2.65v to 16v ? ?R 2.65v to 16v ? operating frequency 2mhz ? ? 2mhz ? maximum duty cycle 85% ? ?`?` 85 ? built in switching transistor ? ??????i ? built in open-circuit protection ? `?oi ? on/off control ? on/off ?`C ? very small inductor available ? ??? ? very small package son3024-8 ? ???` son3024- ? applications ? camera flash fo r mobile phone ? ???? package outline ordering information part name package marking pin configuration ordering information tk11891f son3024-8 aa4 see next page 1 t k 9 1 8 1 f t package code storage direction f: son tl: left type l absolute maximum ratings parameter ? symbol ? rating unit g remarks q operating voltage range ?R v op 2.65 to 16.0 v operating temperature range ?? t op -30 to +85 c power dissipation SM p d 600 mw board mount g?r
power&rf 2005 winter 4-19 electrical charcteristics v in =v en =3.0v, t a =25 c value parameter ? symbol ? min typ max units g conditions operating frequency ? f 1.35 2.0 2.45 mhz quiescent current ?? i in,on 3.0 5.0 7.0 ma v fb =1v shutdown supply current ??? i in,off 0.01 1.0 a v en =0v v fb pin voltage v fb ?R v fb 475 495 515 mv switching current limit ? i sw,limit 1.0 1.4 2.0 a switching saturation voltage sw ??R v sw,sat 0.12 0.2 v i sw 200ma v en,high 1.2 20 v v out : on en pin voltage en ?R v en,low 00.3vv out : off open-circuit voltage ovp ?R v ovp 18.5 20.0 22.0 v maximum duty cycle ?`? d max 85 90 % v fb =0v block diagram pwm comp output drive control 7 6 5 8 2 3 4 1 0.495v err amp over current detector oscillator 0.6v reference 3 w-leds driver application ? designed performance input voltage v in =3.0 to 6.5v led current i led =90ma oscillation frequency 2.0mhz inductor peak current 550ma coil (toko) type d312c 4.7 h 1001as- 4r7m r led 5.6 ? l 4.7 h 4.7 f c in i led pgnd 4 8 1 2 3 tk11891f 5 6 7 v in gnd v fb e a.out sw ovp en v in on/off sbd 2.2 f c out 0.1 f c ea
|
