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LM25149-Q1: Question about current limited RC filter for EVM.

Alan Xia
Expert 4505 points
Part Number: LM25149-Q1

Hi team,

1.The current limiting loop on the schematic diagram of the EVM uses an RC filter, but it is not included in the reference design of the Datasheet. The customer hopes to know the parameter selection calculation method of this filter. What is the function of this RC filter? What is the calculation method?

2.Will the RC filtering here have an impact on the feedback loop?

3.The customer's current filtering scheme is shown in the figure, is there any problem? Both ends are 0Ω, and 220pF is selected in the middle.

  • 0
    TI__Mastermind 22299 points

    Hi Alan, 

    I recommend placing a resistor on the ISNS+ line, similar to the 50Ω from the EVM.

    The RC filtering should not affect the loop, it is for filtering any SW node that can couple to the current sense resistor. Just be sure the RC cutoff frequency is 10x greater than FSW to not affect FSW waveform.

    Hope this helps,

    -Orlando