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TPA3221: RC Passive Low Pass Filter

Sadanori Kato
Guru 36490 points
Part Number: TPA3221

Hi,

The RC passive low pass filter is applied to the input stage on TPA3221EVM, so could you please tell me whether that is necessary ?

Best regards,
Kato

  • 0
    TI__Expert 6720 points
    Kato,

    Robert will follow up TAS3221 realted question soon.

    Rdgs,
    Matthew
  • 0 in reply to Matthew Miao
    Guru 36490 points

    Hi Matthew-san,

    Thank you for your reply.

    I am looking forward to hearing from Robert-san.

    Best regards,
    Kato

    kato-s@macnica.co.jp

  • 0
    Guru 140200 points
    Hi Sadanori,

    the RC low pass filters at the inputs definitely make sense. They help to prevent the swichting noise from coupling back into the inputs via stray capacitance. I wouldn't omit them.

    Kai
  • 0 in reply to kai klaas69
    Guru 36490 points

    Hi Kai-san,

    Thank you for your comment.

    If RC low pass filter should be applied to the input stage on TPA3221, this content should be mentioned in TPA3221 data sheet, so I would like to know the reason why this content isn't mentioned.

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    Guru 140200 points
    Hi Sadanori,

    having passive low pass filtering in an audio signal path at several places is good design practise. In extended professional audio mixing consoles you can see it at each OPAmp stage sometimes. But actually there's no need for it. It only improves the performance. Here it's the same, it improves the performance.

    In this EVM the input signal lines seem to be much longer than usual. This makes the signal lines more susceptible against capacitive stray coupling. This might be the reason why the RC low pass filtering was added here.

    I do always have lots of passive band pass filtering in my audio circuits, even when others say it is overkill. But it allows me to achieve a very professional performance.

    Kai
  • 0 in reply to kai klaas69
    Guru 36490 points

    Hi Kai-san,

    Thank you for the information.

    I also agree with your opinion.

    Best regards,
    Kato