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Original question:

TPS40210: PMP4540 questions

TPS40210: R1 and C11 value clarification for PMP4540

Ikoma
Intellectual 940 points
Part Number: TPS40210


Hi Expert,

 

This is Ikoma from TIJ. I got an e-mail from Minami-san to clarify the answer in the previous thread linked below.

https://e2e.ti.com/support/power-management/f/196/t/752259?tisearch=e2e-quicksearch&keymatch=We

Could you keep supporting question from Minami-san? Since the previous thread is already locked, Let me open this new thread.

 

Minami-san would like to know how to fix the value of R1 and C11. According to the answer in the previous thread, 0.1uF for C11 and 4.7 to 10ohm are recommended to construct low pass filter to prevent high switching noise. So, cutoff frequency of the low pass filter will be about 159k ~ 338kHz and will have enough attenuation like <-40dB for >10MHz band. And you expect the high switching noise happen at >10MHz band. Correct?

 

Could you show him such guide line to fix the value of R1 and C11 for TPS40210? Maybe it’s also related with the layout though.

 

Thanks for your help in advance.

 

Regards,

Ikoma

  • 0
    TI__Mastermind 21720 points
    Hi Ikoma,

    As you stated, the resistor and capacitor just creates a low pass filter that helps to attenuate high frequency noise. The values in PMP4540 for R1 and C11 are fine. Typically the corner frequency is set around 300kHz to 500kHz to allow for adequate high frequency attenuation.

    Thanks,

    Garrett