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TPS2376: POE is not recognized by smart Gigabit switches.

Marcel Gielen
Prodigy 10 points
Part Number: TPS2376

POE is not recognized by smart Gigabit switches. The switch does not start to deliver POE power. We designed with TPS2376DDA-H on class 0. Formerly we used LM5073 also on class 0 and that is recognized by all switches.

Does anyone have an idea what could cause this problem.

We used the recommended design for this part.

  • 0
    TI__Expert 5615 points
    Marcel,

    With this limited information, it is difficult to make a guess. Has either (or both) systems undergone UNH-IOL and/or SIFOs compliance testing?

    Do you have any startup waveforms and/or load (PD) schematics we could review?
  • 0 in reply to Thomas Lewis
    TI__Expert 5615 points
    Marcel,

    I wanted to check in as we have not heard back from you in approximately 1 week. Please let us know if possible to provide more details...otherwise, I will go ahead and close this thread.

    Thank you for your interest in PoE products from TI,
  • 0 in reply to Thomas Lewis
    TI__Expert 5615 points

    Marcel,

    I see you have rejected my attempt to close this thread.  I am sorry to hear that you still have experience difficulties.

    Do you have any additional details/waveforms/test reports/etc. that we could review?

    Best Regards,

  • 0 in reply to Thomas Lewis
    TI__Expert 5615 points
    Marcel,

    Without any additional information (waveforms, schematic) this is very difficult to advise on. The system could be failing detection but we need more information to be sure.

    Because there is a UVLO pin on the TPS2376 (and not on the LM5073), an educated guess is to check the design to see if the divider is designed with too much current passing through it. That scenario could result in a failed detection.

    Hope this helps,