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TPS2372-4EVM-006: We are trying to use the pcb as class 4 device but it does not work

Maik Halbe
Prodigy 150 points
Part Number: TPS2372-4EVM-006

Hi,

we are using the TPS2372-4EVM-006 as pd with class 4. A resisitor with 47 ohms and 300 watt is connected to j7. The jumpers are set to

- CLSA -> class 4

- CLSB -> class 4

- J4 / MPS_OUTY -> VSS

- J5 /Autocls -> closed

- J6 /IPSHDL_EN -> closed

- J10 Port1 current -> closed

- J11 AMPS_connect -> closed

If we connect the pcb with our poe-switch (54 volts) and then second step connect the load-resistor the pse tries to power the load but that does not work. Do you have an idea what is the reason for this problem. 

Thanks for your help.

  • +1
    TI__Expert 3700 points

    Hi,

    Thank you for your question.

    It sounds like you are overloading with (54V)^2 / 47ohm = 62W load when the power is set to only Class 4 (25W). Perhaps you could try with <=25W load since the EVM is set to Class 4. 

    Could you also provide some details about what you mean by the pse tries to power the load but that does not work. 

    Could you take some waveforms of what you are seeing when you connect the PSE for VDD_VSS and RTN_VSS? These will show the PoE handshake and what is going on there.

    Thank you! 

    Best Regards,

    Brett Colteaux

  • 0
    Prodigy 150 points

    Thanks for your help. I ordered a second resistor and made a series connection. Now it works and i will go on with testing.

    Kind regards,

    Maik