Looking for 12S to 5V buck converter (~200 mA output)

I’m looking for a small and reliable buck converter that outputs 5V (doesn’t need to be adjustable) and can take up to 12S as input. It has to be able to output as least 200 mA.

Does anybody know about one? Or can anyone design one that could be manufactured with the JLCPCB (or similar) SMT service?

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I use this one in my builds. It’s pretty small compared to other (maybe cheaper though) UBEC.


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I will try these in my next builds:

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Using this one, it’s bigger but it can take a few amps. Have used it for thousands of km in my case. https://www.aliexpress.com/item/32912011020.html?spm=a2g0s.9042311.0.0.27424c4dNsizpA

I have multiple LM2596HV chips, handles up to 56v, can do 5v 2A no problem. Tiny footprint too.


CC/CV with no mounting holes

CV with mounting holes


Thanks everyone for links. I’m looking for as small as possible. No need for high current rating. I currently have a few that look very similar to what @BluPenguin has linked. I was hoping for something flatter though. It must be doable. My FlexiBMS has a smaller footprint than that one buck converter and it does a whole lot more things than just output 5V.

You could remove the potentiometer and solder resistors in there to get it slightly slimmer, but the caps are going to be the thinness blocker

You can get just the LM2596HV chip and hook up resistor and caps. at 200mA, you don’t need those large caps, so you can save some space there.


Been looking into these as well since I was wanting to design a lighting system based on arduino and would need 5V and 12V power. Think the 5V would need to output 3-4A since I’ll be running a strip of WS2813 RGBs underneath as well as the arduino from it.

I can design one for you.

Use the fancy new chips for lowest power



LM5166 is available for JLCPCB SMT. Not exactly cheap at ~$5 but it takes 3-65V input and can output up to 500 mA.

Plus, the example circuit on the front page of the datasheet (for 5V output) seems exactly what I need and looks simple enough even for me to design. :slight_smile:


Thanks for the pointer @Gamer43.


Use a discrete power rated resistor for the “Resr” designator in the design on the front of the datasheet, unless you opt to use an electrolytic capacitor for your output capacitor.

Also, LCSC does not have the LM5166X, the fixed 5V output version, you’ll either have to get the part from somewhere else, or add in a resistor divider for the feedback circuit.

Exposed pads can be soldered using a standard soldering iron, the trick is to have the pad on the PCB exposed on both sides with a small hole in the center of the pad, you solder it from underneath. What I do is I tack on each of the pins first, then flip the pcb over and solder the ground pad.

EDIT: nevermind, just realized the package is no-leads cancer, I would recommend using the LM5163 instead.


How’s this specific model work? Would it work for a 12s battery?

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Yes, that will work fine for a 8S - 12S battery.

You could probably use it for 13S or 14S but I wouldn’t use it for 14S.

15S is no bueno.

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Does anyone have experience with the waterproof versions?

The magic “DC/CD” converter. I’m hoping it’s just a fixed output TI LM2596 bathed in epoxy.