TPS23841: Discovery Issue

Jerry Fraschilla

Part Number: TPS23841

TPS23841 is in auto mode.

It successfully detects a PoE camera.

With a POE Splitter (POE21-120) the discovery seems to fail. The discovery fail bit is set in Status 1 register, but it also shows that a class 1 device was detected. It seems like maybe it got part way through the discovery process. No faults are reported. Power is being supplied to the POE splitter.

over 3 years ago

0 Darwin Fernandez over 3 years ago

TI__Mastermind 40905 points

Hi Jerry, can you help take a waveform of the voltage signal (and current if possible) of the RJ45 during discover and negotiation of the PSE and PD? I would have expected the PSE to power up to Class 0 (13W) if a Type 2 PD is connected to it.

Have you tried connecting a Type 2 PD TI EVM just to try another 25W PD? Thanks!

0 Jerry Fraschilla over 3 years ago in reply to Darwin Fernandez

Prodigy 20 points

We have tested with a POE Camera which is reporting discovery completed without issues and reported a class 2 device.

0 Darwin Fernandez over 3 years ago in reply to Jerry Fraschilla

TI__Mastermind 40905 points

Thanks Jerry, it seems the issue is with a Class 4 PD on the splitter. I'd like to see if the issue really is the PSE or if it is the splitter that may be misbehaving. If a Type 2 PD (I recommended a TI EVM since we put these EVMs through extensive compliance testing) passes with the PSE, then we can potentially say the splitter could have issues. Please let me know if this helps. Thanks!

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TPS23841: Discovery Issue