G070CBT6 Strange issue with reset line falling down...

[MKowalski]

Hi, I'm facing a very strange issue with my G070CBT6-based board...

When I start work and power up the board everything works fine for a couple of minutes (let's say 5 minutes ) but later I can observe some disturbances on the reset pin... I connect the oscilloscope and I can see the voltage on the reset pin, after a few minutes of the device operating, starts to fall down slowly and there is some mess on the signal...

Here is an example waveform watched:

Yellow -> 3.3V supply

Blue -> reset line

 

I've tried 3 different pcs of the MCU on the same board and also try soldering bare minimum setup (LDO, MCU, caps, etc.. ) on a totally fresh PCB, and every time the same behavior...

No matter, if the code flashed, is my application code, led blink demo, or totally erased flash.

This is the MCU part of the schematic..  I also tried to pull down the SW_CLK ( there is the BOOT0 also on this pin ) but this ain't help...

When the issue occurs, I'm not able to do anything with the MCU. It is "held under reset" from the SWD perspective. If I leave the board unpowered for some time to "cool down" it starts operating again, but again only for a couple of minutes... The MCU is not getting hot or something... supply is very stable 3.3V...

Any ideas what is going on with this? I have never had similar issues and I doubt that I broke the MCU during soldering...

[SofLit]

Happy to hear that.

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@MKowalski wrote:

If the issue will not occur again till the end of the day I will consider this topic closed.

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If you will close the topic, please accept the comment that guided you to the solution.

Thanks.