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UCC28780: Calculation of COSS_QH_T, COSS_QL_T

Part Number: UCC28780


Good Day. I have a customer who wants to know the formula of the calculation of COSS_QH_T, COSS_QL_T on the excel file.

6281.UCC28780 (1).xlsx

I hope you can help us with his query. Thank you very much.

Best Regards,

Ray Vincent

  • HI Ray,

    Since the Coss of FET is NON-linear , The method used in the calculator is integrating the coss curve . the integration is done by discretizing the Coss curve calculating the area of each segment , and then summing the areas together .

    formula of calculation :  ((Coss_big * Vxl) + (Coss_small * (Vds-Vxl)))/Vds , where Vds =VIN _Nps*Vout, others please refer to curve in the calculator.