Driver advice

Hi Wayne,

I'm in the process of making an aspheric M@glite with a Cree Q5 LED and a single Li-ion cell. Ideally, i'd like to provide it with 1.4/1.5A constantly. Since it's a novelty flashlight it won't be used for more than a few minutes at a time, so overheating the LED shouldn't be an issue. It appears that I may have to parallel a couple of boards unless any of them can be modified to output ~1.5A safely.

The two boards that seem to suit my needs are the BB Nexgen and the GD buck/boost. Is it possible to mod either of these to 1.5A? If not, is it possible to run either of them in parallel to double the output current?


Thanks

Wayne? Any feedback? If you tell me what I need, you'll have an order!!

The nexgen is a boost only converter and with a fresh battery could be in DD overdriving the LED. Once the battery dropped down a bit the Nexgen would regulate just fine. If that is OK with you that is probably fine. I don't think you will be DD the LED to much harder than 1.5A and possibly less.

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This is just off the top of my head. My gut tells me that the lower Vf LEDs like the CREE XRE will be around 3.6V-4V at 1.5A. This means that a Nexgen is probably safe and would be in regulation most of the time. Most configurations are for a drive level of 1A to the LED and in that case the Nexgen will be in DD for a while. In this case the target is 1.5A and that is closer match of Vf and battery voltage. The Nexgen is a beefier driver and will run more efficiently.
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Either one can be configured for 1.5A.

Both will need a 0.1 and a 0.05 resistor as the correct combination to get 1.5A.

I'm leaning towards recommending the Nexgen. I don't think under this condition you'll have to worry about overdriving past 1.5A under a fresh battery condition. Hot off the charger you'll be pushing the LED a little more when the battery is 4.2V, but, I believe it drops down to 3.7V rather quickly.

Wayne

I don't think I've ever tried paralleling multiple GD or Nexgen and maybe someone else has, but, I have not tried it.

In theory it should be fine.

Wayne

I have a BB1500 driver and it works fine.

I'd go with the NG1500 as Wayne mentioned, just order the blank board and select the corresponding resistors.

Thanks guys... Too easy