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Original question:

UCC28951-Q1: Excel sheet errors ucc28851

UCC28951-Q1: Why has the recommended calculation of Lmag and Lout changed?

Theodore Pantazopoulos
Prodigy 10 points
Part Number: UCC28951-Q1

Tool/software:

When comparing the calculation used to determine Lmag and Lout, there is a factor of two (2) difference in the following documents:

Lmag:  SLUSDB2B (Equation 28) vs SLUA560D (Equation 8)

Lout:  SLUSDB2B (Equation 61) vs SLUA560D (Equation 45)

The method of SLUA560D is what is used in both the EXCEL spreadsheet (SLUC222) and the MathCAD (SLUC210) file.

Can you please explain why this changed and what the recommended method is?

Cheers,

Theo

  • 0
    TI__Genius 12795 points

    Theo,

    We will check and get back to you soon.

    thanks

  • 0 in reply to Ning Tan
    TI__Guru* 85776 points

    Hello,

     

    Question 1:

    Equation 28.  Effective switching is the primary switching frequency times 2.

    Equation 8 uses effective switching frequency instead of primary switching frequency times 2.  The calculation should yield the same results.

     

    Question 2:

    Equation 61.  Effective switching is the primary switching frequency times 2.

    Equation 45 uses effective switching frequency instead of primary switching frequency times 2.  The calculation should yield the same results.

     

    The reason why two different equations were used is because two different engineers derived them.  They will still yield the same results.

     

    Regards,