3W LED Driver

[Zinger]

I need a small form factor constant current driver for a 3W RGB or RGBW LED.  It should run off 5 or 12 volts and be controllable with logic level signals from an Arduino.  A 3W RGBW LED with built-in driver would also work.

My project is pretty small.  I need to fit the driver, LED and Arduino Nano or similar microcontroller in a 3" x 3" 3/4" case.  It's for a desk lamp for a friend.

I've found several parts that work for lower power LEDs, some I2C parts that are close and a few that are overkill for what I need. But nothing small and easy to wire for a single 3W LED.

Any suggestions?  I'm more comfortable working with logic level circuits. Something that needs a lot of external components for EMI etc. is probably beyond me.

[Marco]

I'd use inverting buck boost with just the PWM channels from the micro. Inverting buck boost in discontinuous mode at a constant duty cycle and supply voltage will act like a constant power driver, which is just as good as a constant current driver, no need for a sense resistor even.

PS. that link was just the first write up I found of the concept, you can google more. Boost at constant duty cycle can also work as a constant power driver by the way, but that's not really relevant here.

PPS. might want to use RGBWW LED. RGB is nice for mood lighting, but white LED will have better CRI ... so a little more white is probably better.

[Zinger]

The Adafruit Pixie is just what I need.  It's 3W RGB. Has built-in constant current supply and color control. It's small enough to fit in my project and has over-temp protection.  The current supply is linear instead of switched but for this form factor and price I'll accept a little extra waste heat. I need to weight my base so it doesn't tip over.  Might as well use that as a heat sink.

https://www.adafruit.com/product/2741