TPS23882B: Detect and Classification does not work with Shielded Ethernet cable on Dev board with more than one connection

Tom Nixon

Part Number: TPS23882B

Tool/software:

We have recently moved from a 4 port ADI PSE to the 8 port TPS23882B PSE on our product line.

Our new prototypes, which use 6 of the 8ports of the TPS23882B work fine as long as we use Cat5e/Cat6 cables to connect the PoE ports. As soon as we connect more than one PD using shielded cable (ie. Cat6A) however the TI PSE does not detect the PD correctly in semi-auto mode.

We have purchased the TI dev boards for this product, and using the TI software that comes with the two dev boards verified the same results. If we connect one Cat6A all it good, but as soon as we connect more than one the PSE detects random PD (high, low or short resistance) and never validates detect/classification. All cables are 50ft.

Our application requires giga-bit ethernet so shielded cable is pretty important.

9 months ago

0 Noah Zwack 9 months ago

Prodigy 40 points

I'm adding some screenshots here from the TPS2388x GUI tool to show an example of what we're seeing with the Cat6A cables.

With one PD connected:

With two PDs connected:

Note that the detected resistance of one PD has increased while the resistance of the other one has dropped very low. The lower resistance seems to fluctuate as well, sometimes reporting as a short or going higher to around 12 kOhm. The measured current has also dropped to 0.

0 Diang Xing 9 months ago in reply to Noah Zwack

TI__Mastermind 37061 points

Hi Nureva,

Thanks for reaching out!

Does this fault only happens in semi-auto mode or also in autonomous mode? If only in semi-auto mode, could you let me know what is the firmware / SRAM version?

Best regards,

Diang

0 Noah Zwack 9 months ago in reply to Diang Xing

Prodigy 40 points

Hello,

I tested autonomous mode and I'm seeing the same fault. If both PDs are plugged in on start-up, neither of them power up. However, if only one PD is plugged in, it powers up successfully.

In terms of firmware version, I'm not sure where in the TPS2388x GUI it shows the FW version, but I clicked the "Reset Factory Firmware" button so it should be reset to whatever the factory version is.

It looks like the SRAM revision is 0.

0 Diang Xing 9 months ago in reply to Noah Zwack

TI__Mastermind 37061 points

Hi Noah,

We should have version 3 now. Let me check how to get the newest version to customer and get back to you in the week after thanksgiving.

Please try to load 0x03 SRAM version later.

Best regards,

Diang

0 Noah Zwack 9 months ago in reply to Diang Xing

Prodigy 40 points

Hello,

Yes, if you could grant me access to the latest firmware that would be much appreciated. Thank you.

0 Diang Xing 9 months ago in reply to Noah Zwack

TI__Mastermind 37061 points

Hi Noah,

I was trying to check with internal team about how to get the access but many of people are taking time bank today. I will get back to you after the Thanksgiving. Happy holiday!

Best regards,

Diang

0 Abigail Leonardi 9 months ago in reply to Diang Xing

TI__Expert 3390 points

Hi Diang, I just wanted to follow up again here to see if Noah would be able to get access the firmware? Thanks for your help!

0 Diang Xing 9 months ago in reply to Abigail Leonardi

TI__Mastermind 37061 points

Hi Abigail,

I will follow up with you in email. Please help to share with Noah.

Best regards,

Diang

Power management

Power management forum

TPS23882B: Detect and Classification does not work with Shielded Ethernet cable on Dev board with more than one connection