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UCC28740: CS-pin fault

Part Number: UCC28740

Hi Experts,

    I make a reference design about two switch flyback with UCC28740. I tested the PCB but something went wrong. Could you pls tell me why Vcs is so large and how I can fix it. The waveforms are as follows.

  1st channel: the vds of upper mosfet

  2nd channel: the vds of lower mosfet

  3rd channel: Vcs

  4th channel:Vout

Regards,

Skylar 

  • Hi Skylar,

    It looks like you're working on a project for your rotation. I think it's best to start with someone locally in the Shenzhen office to get you going as there appears to be a fundamental issue with the design. Someone from my team can assist as well, but I don't think the E2E forum is the most efficient way to debug this issue.

    Please reach out to me directly via email and I will have someone from my team assist.

    Regards,

    Ray

  • Hi Ray,

        Sure. Jaden is always supporting me in the Shenzhen office and if I need further support, I will reach out to you directly via email. Thank you!

    Regards,

    Skylar