Burn STM32G0 I/O - Page 1
Forum section: electronics / projects

author: delphes123
author_rank: Contributor
timestamp: January 27, 2024, 05:14:16 pm
content: Dear All,I have a Strange things happening on Stress test of my board, schematic is as follow, nothing complicate a N Channel Mosfet followed by a P Channel mosfet to switch load.Load is multiple PCB (4) with capacitive, inductive load , 3 of them have 1000 uF Capacitor on 12 volts input, so let say 3000 uF total.MCU is STM32G031F8P6 and one I/O is used to switch ON and OFF.We run multiple ON and OFF and suddenly after 30 try (but could be more) the I/O of the STM32 burn out and is fully not workable anymore.As you see there are no Gate resistor on N Channel mosfet to protect the STM32 I/O.If you have any idea, please let me knowrgds

author: temperance
author_rank: Super Contributor
timestamp: January 28, 2024, 12:16:19 am
content: Try driving the P-MOS at lower speed and it will work fine. (Resistor to the gate and a capacitor from drain to gate) Because the circuit you posted drives the P-MOS at a very high speed into saturation and current is now only limited by the input supply. From there anything can happen especially if the load is inductive. (I guess some other parts must have failed too)Up to you to calculate the proper values.

author: cncjerry
author_rank: Unknown
timestamp: January 28, 2024, 09:43:26 am
content: I suggest you measure the voltage on that pin in both states. The only time I burned out an stm32 board is over voltage. But I only ever worked with stm32f4 and f7 boards.

author: delphes123
author_rank: Contributor
timestamp: January 28, 2024, 05:05:31 pm
content: Quite difficult to add something around P Channel for test, but I can easily add Gate resistor between MCU I/O and N Mosfet Gate to test like 1K what do you think ?

author: MarkT
author_rank: Frequent Contributor
timestamp: January 28, 2024, 08:21:55 pm
content: I guess the high inrush current blew T25 and this then fried T24 and the pin. Add a gate resistor to T25 to slow down the turn-on so it takes 10ms or so and then the inrush current will be sensible (and not crowbar the 12V supply either).

author: cncjerry
author_rank: Unknown
timestamp: January 28, 2024, 08:43:37 pm
content: You can always add a switching transistor at the mcu pin, no?

author: delphes123
author_rank: Contributor
timestamp: January 28, 2024, 08:45:09 pm
content: What do you mean by switching transistor at the MCU pin ?

author: temperance
author_rank: Super Contributor
timestamp: January 29, 2024, 12:38:47 am
content: Quote1. The not so good guesswork. A 1 K gate resistor for the n-ch fet is way too small because turning on the p-ch mosfet requires less than a few mA (miller plateau and gate drive current define the turn on time. Q= i * t is what you need). But that's only part of the problem. See 2.2. A 2N7002 is not suitable for a 3.3 V micro controller. It might work on a proto type but not in mass production. Take a look at the Vgs ID curves plotted for a typical Vgs-th voltage. The specified Vgs th value might be as high as 3 V and as low as 0.8 V for an on semi device and drifts with temperature. Depending on Vgs-th, the circuit behaves as a current sink or goes into saturation.3. You've got a pull up resistor for the p-ch MOSFET. Can you solder some components onto that resistor? (tip for calculating the required values: miller integrator)