2025-08-04 2:35 PM
Hey y'all!
Sorry if this question is a little silly, I'm pretty new to Electrical Engineering and PCB design (this is my first ever PCB), but I've been having trouble with the board I designed for the STSpin32G4. I've been meaning to use it to do FOC control on a BLDC motor. I've been able to power the board via REG3v3/VDD and VSS at 3.3v just fine (including a blink test), but when I try to power the motor at 9V (using VM and PGND), the chip pops and I get some magic smoke. I replicated the process happening on one of my remaining boards in the video at this link. I've also attached the schematic that I was using, but can't figure out what I did wrong.
Of note: I used all ceramic capacitors except for C21 and C22, they should be parallel lines in the schematic but I messed up when I originally created it, polarity shouldn't matter for those. Also, before posting this I accidentally had each corresponding Boot and Out (1-3) reversed, which on re looking over the datasheet, I realized and fixed, but I don't believe that would cause the issue with the Magic Smoke.
Thank you so much for your help!
2025-08-04 6:19 PM
Are PGND and VSS connected somewhere? I don't see it in the schematic.
2025-08-04 8:36 PM
I don't believe they are - do they need to be? Both are connect to different grounds (the usb 3.3 power ground and the 9v psu ground). On reading I think that might need to be fixed, but I'm not sure if that caused the smoke?
2025-08-05 4:53 AM
They're connected in all the references and diagrams I can find. Would be weird for a chip to have two isolated grounds.