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UCC28750: Apply Gan Kelvin source connection method

user6055081
Prodigy 40 points
Part Number: UCC28750

Tool/software:

If the GaN Kelvin Source pin is connected to the controller's GND separately, the current sense path in the flyback application will be shunted, so that the controller's VCS cannot read the correct current sense value. Does this still depend on whether the controller has an independent driver source pin? If the Kelvin source pin here cannot be separated, would you recommend that I connect it to the power source pin? Or is the Kelvin source pin No connection?

Or is it possible to connect several 10 ohms in series with the Kelvin source?

  • 0
    TI__Genius 12795 points

    I think you misunderstood the SS pin definition in Infineon's datasheet. SS is the gate drive ground, not the FET ground. the current still flow through the S pin, which will be captured by the external shunt resistor and monitored by the CS pin of the controller.

    On the side note, UCC28750 drive can go as high as 12V where the GaN FET takes 5V input only. You need a driver in between.

  • 0 in reply to Ning Tan
    Prodigy 40 points

    FET S and FET SS are connected together. This problem has been clarified. In flyback applications, the 2 pins need to be connected together. If FET SS is connected to the controller ground alone, the current sense will be shunted, causing VCS detection problems.

  • 0 in reply to user6055081
    TI__Genius 12795 points

    Since this question is more for the FET, I think it should be answered by the FET vendor.

    Nevertheless, I am trying to clarify that with the vendor too but it may take some time. 

    Thanks for understanding.