14 September 2010

5W LED and heat

LEDs were the first components I fell in love with, when I was a 10 years old or so. The (recent) introduction of high power LEDs (1W, 3W, 5W, ...) has tickled my curiosity again.

I know from their datasheet that they have a rather small angle and need heat dissipation.

The shop in town offered me a cold white 3W LED for 10€: too much for an experiment. The Net comes handy, with a 5W LED at 3.5€ shipped from China.

It's from "DX", part number sku.4516.

The LED is soldered on a star for easier mounting on heatsink, and should work at 7V, 0.7A. My sample has a forward voltage of 5.9V only (out of specs?!), but it's really like having a star in your room, even at lower current drives!

With a combination of power resistors and a wall-wart supply I managed to run it at 0.32A, that makes about 2W input. Far from the specified 5W, but it does heat nevertheless! The heatsink was donated by a TDA4866 found in my collection of unused boards and for a very lucky coincidence it has threaded holes 20mm apart!! Just perfect for mounting the star!

By the way, if you need a TDA4866 contact me :)

Heat. After the initial warmup, the LED+heatsink reaches about 40°C at room temperature of 25°C. Wow, and I'm running it at half power!

In the next post I will show a possible application of this LED, and the comparison with two halogen spotlights in my kitchen.