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
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)
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
Are the control wires hooked up?
Share a photo of the setup
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?
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