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Original question:

TPS2372: PoE switch not recognizing PD device and providing power

TPS2372: Device not recognized by active PoE switch

Jorg van Asseldonk
Prodigy 50 points
Part Number: TPS2372
Other Parts Discussed in Thread: TPS23880EVM-008, USB2ANY, BOOST-PSEMTHR-007, TPS23880

For a 60W POE application I used the TPS2372 to handle the negotiation, schematic for the relevant parts added as PDF.

The design works with passive PoE injectors, but active ones indicate there's an issue in the recognition process.

I've based the design off the 'recommended application' in the datasheet, is there anything i might have done wrong?

POE Recognition.pdf

  • 0
    TI__Expert 5615 points
    Jorg, You have reached out to us over a holiday break for Texas Instruments' employees based in the US. Everyone is off until next Monday (4/22). We will get to your request, in detail, ASAP next week.

    While waiting for our reply, it would be useful to know what active PSE is causing the issue at connection. There are some active PSE controllers out there that are not fully interoperable with IEEE802.3bt-ready PD loads. It would be very useful to help you debug the situation if we could know what you are connecting to.

    I would also recommend that you read more about the long-term solution to this issue (a PoE logo program) here --> e2e.ti.com/.../724427 .

    Thank you for considering PoE products from Texas Instruments,
  • 0
    TI__Genius 15655 points

    Hi Jorg,

    Can you get the detection classification status from the PSE? If not, I recommend you test your PD with TPS23880EVM(TPS23880EVM-008_BOOST-PSEMTHR-007 and USB2ANY) and see if you have the same issue and you can also read all status from TPS23880EVM GUI. Thanks.

    Best regards,

    Penny

  • 0 in reply to Thomas Lewis
    Prodigy 50 points

    The POE injector used to power my design is the 'Phihong POE60U-1BT'. According to its datasheet this part should be an active (IEEE802.3bt compliant) injector.

  • 0 in reply to Penny Xu
    Prodigy 50 points
    Thank you for the suggestion, I'm afraid I do not have access to any evaluation tools for the POE. To tackle the issue at hand I only have access to standard measurement equipment (oscilloscope and multimeter).
  • 0 in reply to Jorg van Asseldonk
    TI__Expert 5615 points
    Jorg,

    If you have noticed, TI does not claim IEEE 802.3bt compliance on any of our solutions yet, as there is no released certification program available to test with yet. There is a logo program underway...and Type 3/4 (aka, IEEE 802.3bt) certification logos will be available by the end of the year through the Ethernet Alliance. TI is a very active member on the committee working to define that test suite. You can read more about program, and logo, in our FAQ located here --> e2e.ti.com/.../724427 .

    Penny's suggestion remains the best way to debug your situation. You can order our TPS23880 EVM kit...hook it up to your TPS2372-based design and see if the issue remains. If not, the classification issue resides on the PSE side of the cable. If it remains, reach back out to us and we will work with you to figure out what is happening.

    Penny is also on this thread and might come with additional suggestions (utilizing only the oscilloscope and multimeter) as well.

    Thank You,
  • 0 in reply to Thomas Lewis
    Prodigy 50 points
    Thomas, thank you for your (very fast) reply. Your answer clarifies the potential issues with interoperability, for now I'll reach out to project management to see if acquiring the kit is an option. Any suggestions as to alternative solutions in the meantime would still be very much appreciated.
  • 0 in reply to Jorg van Asseldonk
    TI__Mastermind 40120 points
    Hi Jorg,
    Looking at the schematic, I believe the data transformer connection is incorrect. The pairs should be 1,2/3,6 instead I see 1,2/3,4. Please see TPS2372EVM as an example.

    The standard requires it to be 1,2/3,6 and 4,5/7,8

    Regards,
    Darwin
  • 0 in reply to Darwin Fernandez
    TI__Expert 5615 points
    Thank you for checking Darwin!

    Jorg, Please check this and let us know if that resolves your issue. It likely will.

    Thanks,
  • 0 in reply to Darwin Fernandez
    Prodigy 50 points

    Hello Darwin,

    Thank you for your reply, I've tested it and unfortunately it did not resolve the issue. The PoE injector I'm using still indicates an error.

    Regards,

    Jorg

  • 0 in reply to Jorg van Asseldonk
    TI__Mastermind 40120 points
    Hi Jorg,

    Have you tested the injector with a TPS2372EVM just to make sure the injector is not the issue?

    Looking more at the schematic, can you try removing C7? I have never seen the bob smith termination connected to primary ground in the past. Also note the data transformer looks backwards. The MX and MCT side is the PoE side while the TD/TCT side is the data side. I don't believe the data side is rated to have power flowing through it. The EVM is a good example on how to do the connections. Also, I have connected the TPS2372EVM to the Phihong BT injector in the past with no issues.