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LM5140-Q1: MOSFET power loss calcuation in LM5140ADESIGN-CALC.xlsx

Sam Kim
Prodigy 510 points
Part Number: LM5140-Q1
Other Parts Discussed in Thread: LM5140ADESIGN-CALC,

Hello,

The power loss calculation of MOSFET in LM5140ADESIGN-CALC.xlsx do not match with the result from datasheet equation. Both high side mosfet switching loss and low side mosfet deadtime loss are not correct.

Can anyone check the equation in this design sheet?

Regards,

Sam

  • 0
    TI__Expert 3545 points

    Sam,

    Thanks you for your feedback.  You are correct, I found two errors in the MOSFET power loss calculations.  In the high side switching losses the IOUT term is missing.  In the deadtime losses, there is an 2 time multiplier in the equations that need to be removed.  I will make the corrections and have it up loaded to the web as soon as possible.

    Terry Allinder

  • 0 in reply to Terry Allinder
    Prodigy 10 points
    Hi,
    There are more errors in this file:
    - Cell C45, calculates Cout based on Eq 27 from datasheet. It has wrong terms: Dmin instead of Dmax, 0.1 instead of 0.01 , VinMax instead of VinMin
    - Cell C40, calculates Cout based on Eq 25 from datasheet. It has a problem due to Vcs can't be selected as 75mV in cell C21


    I have some suggestions,

    - IOUT (rms) based on Eq 29 from datasheet is missing in the xlsx file, and it is useful to select output Capacitors
    - I think you should unprotect cells and use "named cells" to clarify the used equations.
    - At least values in the xlsx file should match with the whole calculus done in the application example in datasheet

    Regards,
    Juan
  • 0 in reply to Juan Cecconi
    TI__Expert 3545 points

    Juan,

    Thanks for your feedback on the LM5140-Q1 Quicklstart calculator, I'll take a look at it, and make the corrections.

    Terrry