Driving Cree XP-L LED

Hi Guys,

I've got an old railway lantern that I am converting it to LED. I have an Adafruit Neopixel ring to take the place of the coloured filters but am fitting a CREE XP-L LED in the middle of the ring to be a torch.

I'm using an Adafruit Pro Trinket 5v to run everything inside the lantern, and with power from a bank of 18650s.

The LED pulls a max of 3A at 3.25v Vf. What driving circuit can I use so that I have full control of brightness from the Trinket?

Many thanks in advance for your help!

Ross

Ross, you need a constant current driver with a current output to match your led and a pwm control input. Constant current drivers are easy enough to find, but they don't often have a pwm control input. You can't apply pwm switching to the input or output of an ordinary constant current driver using a MOSFET, it would prevent the CC driver from working. Keeping the led cool is also very important. If you can find a way to thermally bond the led to the metal case of the lamp, that would be good.

Thanks, Paul! I'll start researching into one of these.

I plan on running heat pipes from the LED to the case, in an effort to keep it cool. I want to move heat from the back of the LED as this is where the switching mechanism is, and I'm trying to replicate the original switch arrangement.

Heat pipes would be a bit overkill. A good metal-to-metal contact should be enough.