I came up with this idea, tested it and implemented it a while back, but I never got around to writing the article. So here’s the first new circuit article I’ve posted in well over a year. The basic idea is very similar to what Philips implemented with the Xitanium driver for Luxeon Star LEDs. It’s a current-regulated driver, and there are a few design advantages over a voltage-regulated resistive approach. And it’s cheap.
In response to reader feedback, let me also point out that this design is not optimized for efficiency, so it is probably not a circuit you would want to use to drive a Luxeon Star in a flashlight or other power-constrained environment. But for a lot of applications, this appropach works fine.
The basic theory here is to use an LM317T adjustable voltage regulator with a current programming resistor to get a constant current source to drive the Luxeon Star/O safely.
a simple circuit to drive Luxeons safely
Page: 1 2 3 4 5