Driving an LED on a Primary CR123

[sween1911]

Hello!

I have an application that requires using a single primary CR123 to drive an XP-L. 17mm driver size required.

Most drivers start at 3V for a lower voltage range, optimized for Li-ions but just out of reach of a primary.

I'm looking into these two from Mountain Electronics as the voltage range starts at 2.5v and has all the other
features I want. Concerned though because it appears they all have low-voltage cutoffs that will start stepping down.

http://www.mtnelectronics.com/index.php?route=product/product&path=67_117&product_id=663

http://www.mtnelectronics.com/index.php?route=product/product&path=67_117&product_id=715

These are about as close as I can get, anyone recommend a better driver for this application?


Thanks!
- Joe

 

[Tobias Bossert]

Re: Driving an XP-L on a Primary CR123

None of them will work for your project!
The voltage of primary CR123 is below the voltage needed to drive cree XP-L at reasonable power.
If you are fixed on a single primary CR123, you will need a buck-boost driver.
But on the other hand there is a mismatch between the power range of XP-L (up to 10W) and a single primary CR123 which is fine for lower power levels only.

 

[sween1911]

Re: Driving an XP-L on a Primary CR123

Tobias,

Got it, thanks!

If I used an LED that needed less current, like an XP-G2, I assume I'd still need to use a boost, like the kind from a 2AA light?

Any good sources you guys like for that size driver?

 

[arek98]

Re: Driving an XP-L on a Primary CR123

Will be hard to find such drivers. You could try boost only driver but if Vf is lower than battery it would be basically like connecting battery directly to LED.
Some boost drivers:
http://kaidomain.com/Circuit-Board-...Groups-2-to-5-Mode-Boost-Driver-Circuit-Board
http://kaidomain.com/Circuit-Board-...-1-Mode-Flashlight-Boost-Driver-Circuit-Board
http://kaidomain.com/Circuit-Board-...m-0_9V-3_6V-3-Mode-Boost-Driver-Circuit-Board



What are you trying to do? How much light do you need?
Maybe just use something like TerraLUX Maglite AA upgrade module, just connect 3V battery to it and you good.

 

[sween1911]

Re: Driving an XP-L on a Primary CR123

Will be hard to find such drivers. You could try boost only driver but if Vf is lower than battery it would be basically like connecting battery directly to LED.
Some boost drivers:
http://kaidomain.com/Circuit-Board-...Groups-2-to-5-Mode-Boost-Driver-Circuit-Board
http://kaidomain.com/Circuit-Board-...-1-Mode-Flashlight-Boost-Driver-Circuit-Board
http://kaidomain.com/Circuit-Board-...m-0_9V-3_6V-3-Mode-Boost-Driver-Circuit-Board



What are you trying to do? How much light do you need?
Maybe just use something like TerraLUX Maglite AA upgrade module, just connect 3V battery to it and you good.

Here's my goal: I have a customer with a single-cell flashlight that had a 17mm board and a 16mm XPL and they want to use a primary CR123.

 

[HarryN]

Re: Driving an XP-L on a Primary CR123

With a CR123 primary and an XP-G2, just a simple resistor can be used instead of a driver for a single brightness flashlight.

I used to build similar ones using LEDs in the past.

If you like, I can look around and see if I still have some of the high power / 2 ohm resistors around. I think they were a 1206 or something in that size range. I had some special ones made in AlN that are remarkably good at heat dissipation.

They are about 2x3mm so fairly small if you can work in that size range.

Lumileds also makes a ton of LEDs in the sub 3 volt Vf range.