Could anyone here help me?

vvvv beta general
1

Greetings~
Could anyone here help me? I am a bit of newbie to touch electronics. The circuit which is based on LM2596 is given below,please have a see.

8.23.3.jpg1080×593 284 KB

This is a circuit change voltage from 12V to 4V. The P-MOS is the MOFSET of AO340.
I don’t know why it’s useless.
I have measured it. The source electrode–12.26V, grid electrode–11.89V,drain electrode–0.145V.

Was MOS broken? Or LM2596? Is it suitable here? Please help me,thanks!

2

You know. This is not an electronic forum.
Anyway, check if the resistors are inverted on the actual board: if R203 and R204 are inverted.

12.26V * R203 / (R203 + R204) = ~11.86V (Nice voltmeter, I’d say)
Here we have resistors inverted

12V * R204 / (R203 + R204) = ~0,39V
Here we have the voltage as per schematic: correct resistors order

12V * R204 / (20K + R204) = 4V
Here we have the voltage as per schematic: correct resistors order, but with R203 = 20K

Please, let us know.

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