Using Laser Diode Drivers for LEDs?

Flashlight Modding and DIY Parts
1

Hey guys, I just started browsing Laserpointerforums and stumbled on this thread which lists most of the drivers that the community has built.

I was wondering if any of the gurus here will be able to chime in on the differences between laser diode and LED drivers? Are we able to use those laser drivers to drive LEDs?

The FMT 1.7A 3.0-5.5v buck/boost driver looks particularly enticing since it’s 15.8mm in diameter :smiley:

2

That one looks like it would drive an LED just fine. It’s a simple constant current driver.

Some laser drivers use a photo-diode’s Imon current for feedback, and those will probably NOT drive an LED successfully.

PPtk

3

Thanks PPtk! I knew you’d know :bigsmile:

Would it be safe to assume then that the FMT driver will be more efficient than a 7135-based linear driver (at the same output current) within the input voltage range of a single li-ion ?

4

There are a few laser drivers that work well at or below 3Amps…The price of a purpose designed laser driver makes it a poor option ( no pun). A Flexdrive is $30.00 if you can get one and its also 1/4 the size of a NJG driver.

5

Laser drivers are more expensive, but have very little ripple because laser diodes are very sensitive to current spikes.

It’ll work just fine. :slight_smile:

6

Thanks for the great input guys.

7

Just wondering, why are you using a laser driver to power a LED? :slight_smile:

8

Well I haven’t seen a buck/boost driver for LEDs like that FMT driver I linked in the first post - ~1.7A output current and small enough to fit in a P60 pill = yay!

All these laser drivers also seem small enough to fit anywhere!

The only downside is that they’re pretty much all single-mode only I guess. Oh well you can’t have it all :wink:

9

Good point, a buck-boost drive is uncommon for LED drivers.

I’m assuming you’re going to use a single LED in your P60 host… are you trying to use multiple battery configurations?

10

Yeah I’m thinking of a single LED in a P60 module, but it looks like the input voltage range of the FMT driver limits it to only single li-ion.

The main advantage of it (I’m assuming) is that it might give slightly better efficiency than a 7135-based driver.

11

What I want to find is a simple, inexpensive flashlight driver to push 200-250mA to a bluray diode. I paid $20 for a flex drive and farged it up. Don't want to do that again.

12

Personally, I have three gripes about using this driver as an LED driver:

  1. Price: many times more expensive than a LED driver, as a result of its low ripple and high stability.
  2. Limited max current at 1.7-2.6A (buck)
  3. Needs solid heatsinking. I’m not sure if this heat means the driver is inefficient.

Linear drivers aren’t too bad, and I’d rather find good buck alternatives, such as http://dx.com/p/26110.

Unfortunately FastTech doesn’t have a wide selection of buck drivers… yet.