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UCC24612: Back powering LLC output with Synchronous Rectifier

UA&A_CodyDowling
Expert 1006 points
Part Number: UCC24612

TI Team,

We have designed a universal input SMPS (PFC + LLC) with an output of 25VDC. It uses two UCC24612-2DBVR devices in the SR section. Our client's CM would like to power the +25VDC net during some of their tests without having to power up the SMPS. In this use case, a lab supply is connected to the +25VDC net and ground nets via test points as shown in the graphic below. Since the UCC24612 is connected to this net, I would like to confirm that there any risk to the the synchronous rectifier controller in this scenario.

Can you confirm?

Thanks in advance!

  • 0
    TI__Mastermind 27105 points

    Hi Cody,

    The only concern would be when the 25V external voltage is 1st applied to the output you may see some momentary ringing on the drain pins which might cause the SR to turn on. 

    I would advise momentarily depopulating the turn-on gate resistor in the EZDrive circuit just to be safe. 

    Best Regards,

    Ben Lough