1 elm 900 x cmos white led ?ashlight driver g e neral description 2 - elm 900x is cmos white led ?ashlight driver. this series can drive two series connected white led by 1.5v to 3.0v input voltage. ELM900 series uses an external inductor as voltage booster and consists of an oscillator circuit and a driving transistor. the input dc power is transf ormed to constant current pulse when the external inductor is switched on and repeatly at the frequency : 35khz, 55khz. ? low noise : 35khz , 55khz (constant frequency switch ing) ? constant av erage power control ? high efficiency ? p ackage : sot - 89 ? whit e led ?ashlight ? laser pointer ? lcd backlighting elm 9 00x - x symbol a switching f requency b : frequency 35khz d : frequency 55khz b taping d irection s: refer to pkg file n : refer to pkg file pin no. pin name 1 v ss 2 v dd 3 lx sot - 89 (top view) ? ? ? ELM900 x - x a b parameter symbol limit unit max.voltage ( vdd to vss ) vdd 12 v max. vol tage (lx to vss ) vlx 12 v max. current lx ilx 200 ma power dissipation pd 5 00 mw operating temperature top - 20 to + 70 c storage temperature tstg - 55 to + 125 c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? f eatures applica tion maximum a bsolute ratings selection guide bloc k diagram pin configuration
2 parameter symbol condition min. typ. max. unit power voltage vdd 1.0 5.0 v current consumption iss vdd = 3.0 v 7.0 14.0 a output current of lx pin ilx vdd = 3.0 v 90.0 ma leakage current of lx pin ilx l vdd =lx = 6.0 v 1.0 a oscillation frequency : 35khz fosc vdd = 3.0 v 22 35 55 k hz oscillation frequency : 55khz 35 55 75 duty ratio : s witching 35khz duty vdd = 3.0 v 45 55 65 % duty ratio : s witching 55khz 45 55 75 appliaction c ircuit ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 1cell 1led ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 2 cell 2led top = 25 c electrical characteristics marking elm 900 x cmos white led ?ashlight driver 2 - products lot no. ELM900b 0 to 9 ELM900d a to z (i, o, x expected) a , b : p roduct ic code 9 0 c : th e assembly lot no.1 ? ? ? ? s ot - 89 products lot no. ELM900b a to z (i, o, x expected) ELM900d 0 to 9 d : th e assembly lot no.2
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