Hey, does anyone know of a buck driver that can handle 3s input and drive a 6v LED (XHP70.2)?
Looking for something between 10 and 20 amp current.
.
Currently using a 32x7135 linear driver with a buck regulator, and it is too bulky and inefficient.
Thanks in advance!
Hmm.
Perhaps Lexel has a solution for you? Just ask him if you need it.
What diameter are you seeking. This 32mm can easily drive 10amps and is usually under $10. I can't recall how hard I have driven it. I drove it at 21amps in a TK75 here. (Sorry 7 amps into 3S XML2's). I have driven MGT2's into the low teens such as here. The UI is not great though. Five modes you have cycle through. I always piggy back a different MCU when I use one.
Any diameter tbh, I think I can fit up to 60 or 80mm.
UI doesn’t matter.
There was this LD-29S on Kaidomain, with 10A schottky onboard so it would have “overclocked” nicely I believe. Running three of them in parallel… 
If space is not a concern:
Bigass 20A buck converter: https://www.aliexpress.com/item/-/32856019911.html
Replace 100KΩ constant current trimpot with a knob equipped potentiometer (logarithmic taper recommended).
For battery protection:
Used one of these in a drill, works great.
Cheers :-)
Original post date: Thu, 08/02/2018 - 02:14. Edited for a detail.
Am I the only one who thinks that “buck driver” sounds like a prøn-star name?
Anyway, was gonna also suggest trying one of those boards that takes, say, up to 14V input and delivers 10A+ at a lower voltage. Likely be a voltage output and not current output, but I’m sure there must be something that delivers regulated current vs voltage. Hit AX and just goggle around for “12V led driver” or something creative. 
Yes.
The one I use in the light in my signature goes up to 11A.
It’s very expensive though if you also want dimming.
Thanks guys!
This one seems nice, price is ok, no need for dimming.
On the site it only says 9A, how do you increase it to 11? Or more?
It says up to ~120W output so with a XHP70.2 I should theoretically be able to get over 15A at 7V.
You just need to switch out the sense resistor. It has been tested up to 11A. I think 15A would probably be pushing it, but I don’t know. Just write an email to the owner of the site. There is an Excel file on the site that will calculate the value of the sense resistor for you.
Also note the dimensions. It has a very big coil and a medium sized diameter.
The voltage difference between LED and batteries needs to be at least 2V.
Yeah, 2V-3V is the usual minimum difference. Goggle “mt3608” on AX, and you’ll find an assload of boards for boost-drivers that can output up to 28V or so without an external FET.
The hideous modes (H→L + blinkies)?
Guess that's some sort of joke, but honestly, if Enderman can afford to use up to ∅60 - 80mm of driver board, a full size 20A buck converter can fit. With a logarithmic potentiometer plus an in series maximum current limiting resistor it could work. In my experience, I could make this sort of thing work with two in parallel XL4015 modules whose constant current pots were replaced by a dual logarithmic pot (without in series current limiting resistor), but for some reason I ended up killing the led (an XHP70A) at close to turning it full throttle (half of it died first, of course). 
Cheers ^:)
Look what we have here:
” Single LED with High Current 20A Application using TPS92641”:TI Reference Designs Library
It says Vf between 2.6 and 4.9V but that’s just what they tested it for. There’s no reason why it wouldn’t work with 6V.
It has features similar to the LM3409, so analog dimming should be easy. Come to think of it, the LM3409 might do the trick too, if the external components are beefy enough.
Ok, that sounds good thanks 
Thanks
I kinda want a regular flashlight driver that has some low voltage protection and modes built in.
I can’t use a separate balancer as the 3s batteries are in a separate enclosure, so the flashlight only has access to the full 11.1v.
Input voltage too high though, 3s battery pack can drop to ~9v when almost empty.
I want the light to work at full power until the cells are drained.
Note: the Ampere driver from pcb-components doesn’t have any low-voltage protection! It’s basically a very high quality “dumb” buck driver. To get any extra features you need one of their pwm dimmers (or make your own).
12V is just the input voltage they designed around, their test results include a wider range, look at http://www.ti.com/lit/ug/snvu262/snvu262.pdf
From the schematics it looks like they set the undervoltage lockout to ~10.4V, that may explain the limits of their test procedures.
Anyway, Lexel is the guy who should know what’s possible with the TI controllers.
Enderman, you could also ask BanL for further availability of the aforementioned LD-29S driver. It's just a ∅20mm board, you could fit a handful of them and more in your available space and run them in parallel, or so I believe. Features 3-cell 9V undervoltage warning.
Cheers :-)
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