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LT3956 CIN(Input Capacitor Selection)

Would an arithmetic expression of a data seat be right?

When the price is input and I Calculated, it won't be 4.7 μF(boost mode) ,(my calculation result is 10 μF )

And buck mode,my calculation result is 11.75 μF

  • Hello,

    Thanks for checking the calculation. These equations are rough guidelines.
    It is possible that the guideline text is more important than the equation here.

    I believe that you should design with the capacitance which you have determined.
    More capacitance will not hurt you, it might help.

    The idea here is that given a certain amount of ripple on the input capacitor due to current, we want to limit the amount of voltage ripple to maintain simple DC/DC conversion of this switching regulator. In many cases, more capacitance and/or filters are placed on the input to limit the amount of ripple that the line sees so that electronics on the line are not affected by the switching regulator. This is quite simple to accomplish with a small amount of capacitance, as you have calculated, or more cap and filter for specific EMI requirements.