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Original question:

PMLKBUCKEVM: How to calculate the input current ripple? & Why the output voltage ripple is discontinuous?

PMLKBUCKEVM: input current ripple

LIN SUN
Intellectual 620 points
Part Number: PMLKBUCKEVM

Dear expert:

I want to calculate buck input current ripple. How can choose from formula(5) and formula(6)? I don't know how to judge high and low capacitance,can you kindly teach me please?

  • 0
    TI__Expert 3835 points

    Hi Lin,

    Appropriate input capacitor can usually sustain the voltage in case of any line transients. Increasing the input capacitance helps reduce input voltage ripple as well. There is usually a minimum requirement of input capacitors stated in the datasheet for stability. This will usually follow equation 5. In Equation 6 you can see poor input capacitance can lead to the input current not sustaining and hitting the floor every switching cycle.

    Regards,

    Ethan