TPS2372: POE Lighting - Issues after 1000h of testing.

Hi everyone,

My team is looking for some help troubleshooting a PoE lighting solution we developed using the TPS2372 and TPS922054.

The unit was undergoing a long-term test and failed after approximately 1000 hours of continuous operation at 55VDC and 75W.

Troubleshooting Steps:

1. Initially, I suspected the LED driver (TPS922054), so I disconnected everything that wasn't related to POE classification

2. I then tried to connect just the TPS2372 front-end to the PoE switch to see if it would be detected and classified. It was not.

3. To rule out a problem with the switch, I tested a new, identical board, which worked perfectly.

4. On the faulty board, I measured the voltage between VDD and VSS of the TPS2372. The scope captures are attached. It mostly shows the small triangle waves but occasionally jumps to the larger waveform.

Could these VDD-VSS waveforms indicate an internal failure in the TPS2372? Any insight would be greatly appreciated. I can provide more details or schematic snippets if needed.

Thanks!