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TPS2372-4EVM-006: Input ideal diode bridge between several PD input

xiang tao
Prodigy 100 points
Part Number: TPS2372-4EVM-006
Other Parts Discussed in Thread: PMP20859

Q1：If I use the FDMQ8205A(ideal diode bridge) in the TPS2372-4EVM-006, how does the FDMQ8025A block reverse current to each other？

e.g, if the signal pair input is +57V, and the spare pair input is +56V, the PMOS of Q1.pin4 is closed because its gate is low, and the PMOS of Q4.pin4 is closed too because its gate is low too. So +57V and +56V will be shorted together, I don't think the silicon diodes have this problem,  Sorry I'm confused about it, so I have next Q2.

Q2: If I want to parallel two PD ports in the system, can I short the input like figure below?

  • +1
    TI__Mastermind 37031 points

    Hi Xiang,

    Thanks for reaching out. 

    Q1: On the PSE side, 4 pairs of Ethernet wires (PR12, 36, 45, 78) are from the same voltage source. So it won't short with itself when the high side ideal diode FET turning on.

    Q2: It is recommended to parallel two PDs after the internal hotswap FET. You can parallel them passively or using redundancy control. PMP20859 (www.ti.com/.../PMP20859) is one reference design with power redundancy and priority.  

    Best regards,

    Diang