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UCC28180: DESIGN CALCULATOR TOOL

DENIS ROOSEVELT S
Prodigy 30 points
Part Number: UCC28180

Tool/software:

Hello...

I am referring to the design calculator for UCC28180 PFC ASIC https://www.ti.com/tool/download/SLUC506/01.00.00.0C

In the boost diode calculation I have some query regarding the reverse recovery loss calculation.

In the datasheet the Qrr loss is calculated as shown below.

But the factor 0.5 is missing in the calculation sheet...I guess it should be included for the right calculation of diode losses, where in a normal diode Qrr would be higher.

  • 0
    TI__Mastermind 40550 points

    Hello Denis, 

    Thank you for bringing this discrepancy to our attention. 

    Actually, the calculator tool and the datasheet agree in the total diode losses, but the 0.5 factor is applied to the Prr result in cell C91, instead of to the Prr calculation in cell C90.  Personally, I don't like putting the 0.5 factor in the inappropriate cell (in my opinion). 

    However and more importantly, I don't think that the 0.5 factor should be applied at all.  I think the factor should be 1.0.  

    If a reverse recovery charge Qrr occurs every switching cycle, it represents an average current Irr.  This Irr occurs under a stress of Vout, so for me Prr = Vout*Qrr*fSW.
    There is no 1/2 the charge, or 1/2 the frequency, or 1/2 the voltage.  
    I think the 0.5 factor is a mistake.  

    Regards,
    Ulrich