STSPIN32G4 power supply problems

hardware support
1

Hello, I need help with power supply and my STSPIN32G4.

When I’m using 24V and the built-in converter, I can’t upload any sketches (although there is 3.3V on the output). I was using an ST-Link V2 from a Nucleo board, and after connecting 3.3V from it, I was able to program my STM. Now, I’m using an ST-Link V3, which has no Vcc pin, and I can’t use it properly. When I disconnect the 24V and connect 3.3V directly, it works. I measured the 3.3V with an oscilloscope and didn’t find anything unusual. Where should I look for the problem?

I am able connect to MCU with STM32CubeProgrammer if it help with trobleshooting :smiley:

2

But you are connecting the target_vcc pin on the STLink V3, and GND, right?

There must be something wrong with the power, although you say you can’t see it on the scope so that’s strange…

3

Make sure you have the reset mode in STM32CubeProgrammer set to software reset. Hardware reset would likely disable the buck converter, cutting the 3V power just before doing the upload.

4

I’m using only SWD and SCK lines, so it must be software reset :smiley:

I tried with 12V instead of 24V and then I can upload almost whenever i try, maybe I’ll try change some converter components…

5

Strange, I thought the STSpin buck needed at least 15V to function. Maybe it’s somehow getting bypassed to power the 3V regulator directly?

6

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7

Yeah, but the 5.5V is only if the gate drive voltage VCC is generated externally. If you’re using the built-in buck converter you need a higher VM voltage, since its a buck and not a buck-boost converter…