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TPS23752EVM-145: How to choose output Schottky diode on different classification?

Isaac Wang
Prodigy 20 points
Part Number: TPS23752EVM-145
Other Parts Discussed in Thread: TPS23752

From TPS23752EVM-145: Evaluation Module for TPS23752 spec page 3, the output Schottky diode D17 is work on VFO mode.

For PoE class 1, 2, 3 and 4 application, how to choose output Schottky diode D17 for each class?

What parameters need to concern when I choose output Schottky diode D17?

  • 0
    TI__Mastermind 37101 points

    Hi Isaac,

    Thanks for reaching out!

    SRD is OPEN at VFO mode, which can disable the sync FET with isolated gate drive circuit.

    In VFO mode, turning on Q9 will make Q3's gate voltage ≈ 0 V. Then the secondary side rectification circuit will derived by the Q3's body diode and D17. 

    D17 should be a Schottky diode which has lower forward drop to reduce the power loss. So D17 should have the same voltage rating like Q3, the current rating could be comparable or slightly lower considering VFO mode has lower output current.

    Best regards,

    Diang

  • 0 in reply to Diang Xing
    Prodigy 20 points

    Base on Figure 2. TPS23752EVM-145 Schematic (2) output current is 5A. What current rating for D17?