Dear Team,
Please help to analyze what else can cause the upper side MOS short circuit
Background: The machine is running normally, but the BMC card is plugged in after power off, and it will not restart after power on again.
Reason: The upper side MOS of DRMOS U77 on the COME board is broken down, and the lower side MOS is normal
Power verification action: DRmos maximum current is 40A, ocp is 34A.
1. The stress of the upper side MOS with an additional load of 27A is about 14V.
2. After startup, the sudden change from light load to 55A triggers OCP protection. The stress of the upper and lower tubes is about 18V, which is within the specification range.
3. Short-circuit the 12V after the CPU board slows down the mos, and the DRmos is normal.
4. The whole machine runs for a long time at full load of 27A, and the DRMOS temperature is 91°
Many Thanks,
Jimmy
