Hi anyone who can help,
My POE schematic can be found in my previous post:
https://e2e.ti.com/support/power-management/f/196/p/811015/3002427#3002427
It's working, but yesterday I got a problem. The P-channel mosfet was burned in 10 mins after power on.
At beginning, I connect my POE with my load(about 1.5A~2A, 5V), and use the thermal camera to monitor the heat spots. Everything is normal; Q2 (Si7852DP) was about 55~60 C degree, Q4 (Si7456DP) was about 45~50 C degree. No other high temperature spot found.
But after 10 mins running, the Q1 (Si7119DN) suddenly smoked and burned. This chip was not one of the heat spots. The C2 (0.047uF, 250V, 1206) was not broken with the testing by multi-meter.
Could please tell what's the potential reason to cause it? If (just if) the Q1's gate pin shorted with the source pin, will that cause the problem?
Sincerely,
Kevin