FemtoBuck LED Driver COM-13716

Components & Accessories LEDs
1

I think your FemtoBuck LED Driver, COM-13716 is what I want. I have a Cree MX3AWT-A1-0000-000E50 surface mount LED. It has a forward voltage of 3.7 volts, and a forward current of 350 ma. It has a power rating of 2 watts. I believe your FemtoBuck LED Driver, COM-13716 is all I need to power it. I can supply 12 volts (for example), which is above the 7volts I thin you product requires. SO my question is: with a 12 volt supply feeding your Femtobuck, and my LED connected to the output of your FemtoBuck, is that all I need to power the LED?

Thanks.

HallDis

2

To power it, yes…if you want to dim the LED (not run @ 100% duty) you’d use the control pin pair next to the input power; check out https://learn.sparkfun.com/tutorials/fe … k-overview which will demonstrate its use

You also may need to close the jumper to get full power (660mA @ 3.7v = 2.4w), but I would test it at default first to see if that’s warranted (might be bright enough already)

3

My first time with a Buck converter- I want to power a Cree MX3AWT-A1-0000-000E50 surface mount LED. It has a forward voltage of 3.7 volts, and a forward current of 350 ma. It has a power rating of 2 watts. If I supply 12 volts to the FemtoBuck, 12 volts shows up at the output. If the LED wants 3.7 volts, how does that work?

Thanks. HallDis

4

Are the control wires hooked up?

Share a photo of the setup

5

I have a 12 volt wall wart connected to the input of the Femtobuck. With no load on the Femtobuck, the voltage at the Femtobuck’s output is 12 volts. I hooked up my 2 watt LED, and the current through it is 333 ma, just like its supposed to be. So I guess it is working as it should; with no load, the output voltage is close to the input voltage. I do have another question that is really not Sparkfun’s area, but why not? My Cree MX3AWT-A1-0000-000E50 surface mount LED has a die heat sink. how do I use a die heat sink? Do I solder the LED to a metal sheet?

6

HallDIs:
I have a 12 volt wall wart connected to the input of the Femtobuck. With no load on the Femtobuck, the voltage at the Femtobuck’s output is 12 volts. I hooked up my 2 watt LED, and the current through it is 333 ma, just like its supposed to be. So I guess it is working as it should; with no load, the output voltage is close to the input voltage.

Sounds right to me. Remember the Femtobuck is trying to output a constant current (330mA). So it’ll try its best to vary the voltage to get the correct current. However, if you have no load, there is not much it can do: With no load, there is no current, so it tries to raise the voltage as much as it can. V = I * R