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PMLKBUCKEVM: Input Current Ripple

Aaron Wang
Prodigy 40 points
Part Number: PMLKBUCKEVM

Hi, TI support team.

In experiment 2,I want to calculate buck input current ripple.

How can choose from these two formulas? I don't know how to judge high and low capacitance.

If define High capacitance as J12 SH(Cin=4.7//4.7//4.7//4.7) and Low as J12 OP(Cin=4.7uF), these formulas seems to be wrong.

And could you please tell me whether formulas(6) is correct or not? Because i think that if Iout is high it seems that input ripple is too high and this regulator may not be worked properly.

Thanks for your support!

  • 0
    TI__Mastermind 27030 points

    HI

    4.7uF or higher capacitance can be consider large input cap if fsw higher than 200Khz. before you judge it is right or wrong, you need to know how to calculated the input ripple based on the input voltage, output voltage and output current condition.