mh-mini-360

Last update: Wed Jan 10 13:37:48 2024

Memo about the cheapo buck converter MH-MINI-360.

Presentation

In a nutshell

Pros 😆

It's cheap.

Cons　😢

It has a quiescent consumption of up to 60mA (for doing nothing) which is BAD. So no portable / battery powered project with this.

The adjustable resistor is VERY sensitive (it's 220k and has a swing of half a turn), and will drift

Learnt from experience

It works as a "replacement" of a Li-Ion battery in a Nintendo DS but the DS is picky with the voltage. Must be closest you can from 3.7, a little more is ok otherwise the battery protection kicks in and the handheld refuses to start. That said, the MINI-360 delivers the necessary power for good function, so not a problem of the converter, just a thing to know.

Output formula

In case you want to replace the adjustable resistor with a fixed one, here is the formula:
👉 Vout = 0.925*(R1 + R2)/R2
If you fix R1 as 8.2k (the resistor is a teeny tiny puppy labelled "822"), then formula becomes: R1 = (8865* Vout - 8200)

See the truth table in yellow with fixed R2:

It's so much nicer if R2 would have been 10k...

OmniCalculator tells me that with a 33k and 100k resistor (that are in my resistor box) in parallel, I get 25k resistor equivalent, meaning 3.75 V on paper. Close enough.

Links

Helpful sources

The chip's datasheet

The module datasheet

VERY extensive review at Dr Gough's

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