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LM5160A: LM5160A Evaluation Board - Primary Inductance Value Calculation Issue

Part Number: LM5160A

This is with reference to evaluation board of LM5160A (

Configuration which we are referring to is as below:

As per the above configuration, below are L_MIN Calculations, that is coming around 94uH.  

Same 94uH is the calculated value from excel tool provided by TI (LM5160FBKQuickStartCalculator - FinalVersion.xls) and it is attached for reference.

Can you please help us to know the reason why a lesser value of primary inductance of 60uH is chosen instead of higher value than calculated value L_MIN of 94uH in evaluation board.  


Dhoresh.1524.LM5160FBKQuickStartCalculator - FinalVersion.xls

  • Hi Dhoresh,

    Lower primary inductance has smaller transformer size and more quick loop response at expense of higher ripple current.

    L=94uH is for typical current ripple%  around 40%, primary peak current is 0.72A.

    L=60uH, current ripple% is 56%, primary peak current is 0.78A which is far below 2.1A of high side current limit.

    So both design is OK, it depends on your trade off between size, cost and ripple voltage.