Searching for an ultra-low-power 12V to 3V buck converter module

dakhnod · ‎2025-12-17

Hello,

For a personal, open-source project I need to regulate 12V down to 3V, while consuming as little power as possible (a few uA quiescent current at most) in order to control a motor via BLE, all on batteries.

While I was able to find ICs like the STBLW35, I am unable to find ready-to-use small boards/modules with those ICs.

To me, it seems like the field of ultra-low-power is quite novel for the open-source space. As such, I wanted to ask whether ST could

Share insights about suitable modules with me
Support me and my project with products/evaluation boards

Thank you for your time,

Kind regards,

Daniel Dakhno

Andrew Neil · ‎2025-12-17

@dakhnod wrote:
a personal, open-source project

Could you give some more details of this project?

"ultra low power" and "motor" is an intriguing combination ...

@dakhnod wrote:
Support me and my project with products/evaluation boards

For that, you're probably best to contact your local sales office or distributor - see:

https://www.st.com/content/st_com/en/contact-us.html

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

TDK · ‎2025-12-17

Look on Digikey for buck converters. I am sure you can find 100 or so that fit the 12 V -> 3 V requirement. Expect efficiency in the 80% range and way more than a few uA of quescient current. You will need to know how much maximum current it needs to produce.

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dakhnod · ‎2025-12-18

Hello,

thanks for the reply!

Indeed, a motor and low-power is not so intuitive.

I have, a few years ago, created a BLE-enabled door lock, comparable to the Nuki ones. You can see it in action here: https://www.youtube.com/watch?v=jnUlXBZHBno

Now I want to develop this further, by creating a generalized 12V stepper motor controller board.

Due to BLE, I have the requirement of low power, so that the board can stay online for prolonged periods on batteries.

The motor action happens rarely, so that is not too relevant, and draws current directly from the batteries anyways.

I require 15mA peak current, at most.

Kind regards,

Daniel