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TPS23754: TPS23754 detection failure

Sammi Shang
Expert 4450 points
Part Number: TPS23754

Dear team,

What may cause PSE fail to detect PD? Customer find there are small probability that PSE could not detect PD then try again and again. When PD power up, the load current is small than 10mA.

Thanks.

Best regards,

Sammi

  • 0
    TI__Mastermind 21320 points

    Hello Sammi,

    Thank you for your question. Can you clarify what you say, small probability the PSE could not detect PD? 

    Does this mean one PD and one PSE works and some do not, or do you mean different PDs do not work when tested, but this small group of PDs never work? Can you clarify further?

    Thank you.

    Regards,

    Michael Pahl

  • 0 in reply to Michael Pahl
    TI__Expert 4450 points

    Hi Michael,

    Yes, some PD never work. The test results shows because the load current is too small so that PSE could not detect PD.

    Sammi

  • 0 in reply to Sammi Shang
    TI__Mastermind 21320 points

    Hello Sammi,

    If the load current is too low, the design could potentially not have enough current for MPS. The standard requires at least 10mA of current for the PSE to continue to supply power. Do you know the reason the load current changes from ones that do not work?

    For the ones that do not power up, can you show a scope shot of VDD-VSS?

    Regards,

    Michael Pahl

  • 0 in reply to Michael Pahl
    TI__Mastermind 21320 points

    Hello Sammi,

    We have not heard anything from your end in almost a week. If I do not hear from you in 48 hours I will assume the issue is resolved. You are always able to post here if the issue persists past 48 hours. Thank you for your interest in TI PoE products.

    Regards,

    Michael Pahl

  • 0 in reply to Michael Pahl
    TI__Expert 4450 points

    Hi Michael,

    Customer met detection failure issue when connect with different brand switch. Huasan,TPLINK,NETGEAR could connect well with TPS23754, but Ruijie switch need nearly more times to connect well. Please reference the detection process with Huasan and Ruijie.

    Huasan:

    Ruijie:

    Do you know the PSE solution of Ruijie? Will this influence the detection process?

    Thanks.

    Sammi

  • 0 in reply to Sammi Shang
    TI__Mastermind 21320 points

    Hello Sammi,

    As discussed offline, we agreed the next step is to raise the VC cap. Additionally, change the capacitor value on VDD-VSS. 

    Regards,

    Michael Pahl