Help needed on LED driver

How the White LED is driven in a high power torch ?....am looking for a switching circuit that can drive 1watt/3watt LED's without wasting power... working off 3 to 5 volts

Mike D'Agostino said:

For driving LEDs up to 50 mA, I use LR-12 Packaged in SO-8. constant current mode. Look at supertex datasheet. Use a 24 Ohm feedback resistor.

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I'm just curious - is there any particular reason you prefer the LR-12 to the TL783? I know it's a little cheaper, but the TL783 has tighter regulation, a wider range of voltages and higher current capability.

Hi... Am An Student Can You Help How To Build A Driver Of My Project(step Motor 8 Coils) Pls..... Tanx