Tool/software:
We are having an issue using the TPS2384 chip in full auto mode that is occasionally causing damage to connected PDs. It seems that sometimes, the PSE is immediately providing the full 48V immediately at power on rather than going through the discovery process with lower initial voltages. The screenshots below demonstrate the issue.
During a correct power up, P and N going to the port are both pulled up to 48V, so there is no differential voltage seen by the PD until the discovery process starts. In this screenshot, yellow is the P side going into the PD and light blue is the N side. Purple is P-N, so the differential voltage seen by the PD is correctly around 0V:
Sometimes at power up, we are seeing The PSE fail to properly pull the N side up to 48V, causing the PD to be exposed to 30V to 48V without going through the discovery process. The screenshots below show two different cases of this occuring: one where the N side gets pulled up to around a 10V level, and one where it drops completely and pulls it to ground. In the screenshots below, light blue is the P side, pink is the N side, and purple is P-N again. Apologies for the different colors from the previous screenshots, these were captured on different days:
If possible, I'd like some guidance in troubleshooting this issue.
Thanks in advance for your help!
Ben
