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TPS2373: dual signature (Class 5 + Class 5)

Petr Prachar
Prodigy 20 points
Part Number: TPS2373


Hello there,

we are working on our new PoE device and we want to use the dual signature bt PoE there. My question is, if it is possible to get the Class5 + Class 5 with the two  TPS2373-4.
On our prototypes all working well in single signature mode with one TPS2373-4. We always get the requested class. 
But in dual signature mode with two TPS2373-4 chips we get Class 4 + Class 4 at most, even if we are requesting Class 5 + Class 5. We use following combination of the classification resistors on both PD chips:

Thank you.

Best Regards,
Petr

  • 0
    TI__Mastermind 37111 points

    Hi Petr,

    Thanks for reaching out!

    For dual-signature PDs, all the same classification terminology as for single-signature PDs applies, albeit per pairset.

    The following link may help:

    ethernetalliance.org/.../EA_PoE_dspd_Rev2e_090419.pdf

    Best regards,

    Diang

  • 0 in reply to Diang Xing
    Prodigy 20 points

    Hi Diang, 
    thanks for your reply. I understand how the dual signature working in general. 
    But my question is how to configure your chips  TPS2373-4 to request Class 5 + Class 5.

    I have tried to do it using the combination of Cls resistor, that I mentioned in previous message. But it does not working for me? The PSE that I using for testing says me, that the PD reqest for Class4 + Class4 - dual signature.
    My PSE is Type 4.

    Thanks.
    Best regards,

    Petr


  • 0 in reply to Petr Prachar
    TI__Mastermind 37111 points

    Hi Petr,

    The classification configuration should be the same as single-signature at Class-5.

    - May I know what is your PSE part#?

    - Could you measure the classification events number between VDD-VSS? 

    If you are using a Type-4 PSE and it supports dual-signature PD, you should be able to see 4 classification events for Class-5.

    Best regards,

    Diang