ELM900

WHITE LED FLASHLIGHT DRIVER GENERAL DESCRIPTION ELM900x is a CMOS IC designed for driving white LEDs by one or two dry cell as a power source. ELM900x can drive two series white LED by 1.5V-3.0V input voltage. ELM900x uses an external inductor as a voltage booster. ELM900x consists of an oscillator circuit and a driving transistor. The input DC power is transformed to a 35kHz constant current pulse, when the external inductor switched on and off in 35kHz. In a standard application inductor is needed as external parts. FEATURES Low cost and simple application circuit High efficiency Constant average power control Low noise 35kHz constant frequency switching Compact SOT-89 package APPLICATION White LED flashlight Laser pointer High VF LED driver LCD backlighting PIN CONFIGURATION Pin No. Pin Name 1 VSS 2 VDD 3 LX SOT-89 ( TOP VIEW ) MARKING : Represents the product IC code 90 : Represents the assembly lot number 0 9 repeated : Represents the assembly lot number A Z repeated ( I,O,X excepted ) MARKING Symbol 293 WHITE LED FLASHLIGHT DRIVER ELM900x BLOCK DIAGRAM APPLICATION CIRCUIT 2 cell 2LED 1 cell 1LED 294 WHITE LED FLASHLIGHT DRIVER ELM900x MAXIMUM ABSOLUTE RATINGS Parameter Symbol Limits Units ELECTRICAL CHARACTERISTICS Parameter Symbol Conditions Min. Typ. Max. Units 295