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UCC28600: UCC28600 OVP Resistor

Yang Wu
Expert 3320 points
Part Number: UCC28600

Hi Team,

I get a question about the OVP resistor setup.

In the design calculator SLVC104j, it says Rovp1  =  (Vovp_on*(((Vbias/Vout)*(Vf+Vout_ovp))/Vovp_load)/Iovp_line)    +    (LineOVP/(Npb*Iovp_line)) , which contains two parts (red & blue). 

While in datasheet, it seems Rovp1  =  (LineOVP/(Npb*Iovp_line))

Question is what's the different red parts stands for?

Another question is In the design calculator SLVC104j, what's the t_leakage time (QR Design Tool   B84) stands for?

thanks a lot.

Best regards,

Yang

  • 0
    TI__Guru* 86066 points

    Hello,

    The Rovp1 and Rovp2 resistors also are used for zero current detection in the transformer and output OVP.

    It appears that the designer of the excel design tool did not account for input bulk over voltage.

    If you are programing the input bulk OVP and output OVP.  I would suggest following the data sheet.

    Selecting Rovp1 based on the input bulk voltage OVP and setting the output OVP by adjusting Rovp2.

    The other option is to back calculate the bulk OVP based on the Rovp selected by the excel tool to see if it meets your design requirements.

    Regards,