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LM61460-Q1: design tool GM/PM with zero Cout ESR

Roy Chou1
Genius 13085 points
Part Number: LM61460-Q1

Hi team,

I think there is mistake in LM61460-Q1 design tool excel file. When I input ESR of Cout = 0 and the bode plot will be the straight line, but I dont think this is the correct result. May you help check the formula?  

Roy

  • 0
    TI__Genius 13085 points

    And also Co chosen. when we only enter in Co chosen ceramic, but eletrolytic = 0 and then same issue like above.

  • 0 in reply to Roy Chou1
    TI__Guru 50120 points

    Hi Roy,

    I'll need to check this out and get back to you on this.

    Regards,

    Jimmy

  • +1 in reply to Jimmy Hua
    TI__Guru 50120 points

    Hi Roy,

    It is not realistic to expect ESR of 0 for Cout since even MLCC with the smallest ESR will have some value usually in 1-3mOhm.

    As such it is suggested to use 1mOhm in that cell.

    It looks like the Co output electrolytic cell is okay if you put 0.0000001. For all intents and purposes, this is basically almost no electrolytic capacitance. I'd suggest keeping cell 100 as 0.0000001 if you are not using an electrolytic.

    The bode plot curves should be okay for a majority of common use case applications.

    Regards,

    Jimmy