Current supply for high power LEDs

[alternety]

I am looking for a circuit for a constant current supply for luxeon 1W or higher Stars. My intended use is general lighting and task lighting. Everything I have found on chips and designs assumes supply voltage lower than the LED's operating voltage and uses a boost circuit of some sort. This adds cost and size. I do not want to waste power in equalizing resistors for each LED. Constant current will give better diode light matching.

I would like to be able to make a bunch of the circuits with each being capable of a series string of 1-6 LEDs. I can feed the current source circuit whatever voltage necessary. An off-line supply would be good. The LEDs need 350 ma. Low cost and small size are both key considerations.

Pulse width modulation for brightness and/or power reduction at full visible brightness would be a plus.

 

[blcpro]

Since your power source is so flexible, and cost is an issue, it may be easier to fabricate your own circuit. I would suggest using a driving transistor, perhaps an N-channel mosfet, to drive a string of led's in series with a current limiting resistor. The gate control of the transistor can be PWM to give you brightness control. In fact, if the PWM signal is buffered, several of these circuits could be paralleled!

 

[Jimttx]

Check the Supertex web site.

http://WWW.Supertex.com