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anyone cand suggest a led driver chip? one that requires few external components? it should be able to drive 1-2 white leds from a suply voltage like 2-5V....any ideas? so i could power from something like 2 rechargable batteries....
I'm using the Linear Technology's LT1937 for a project I am doing right now; for my purposes it drives two series white LEDs but it could drive more. There are various configurations, but the minimum configuration would just have the chip, an inductor, a couple caps, and the schottky diode... I think. You can also configure it with output clamping and soft start. Oh yeah, you need a current sensing resistor, too, since it is current controlled.
It seems to work fine, and is in an SOT-23-5 package.
well, you could build your own using a handful of transistors, caps, resistors, diodes and an inductor. It wouldn't be as small but it would work. either way, you're going to need a switching power supply. the only other alternative is a charge pump, but those are severely power limited, and probably wouldn't generate enough voltage to drive two white leds anyway,