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PCM1821: ADC input blocking capacitor size

xin.wang5
Prodigy 40 points
Part Number: PCM1821


With the design of PCM1821 We use single end signal input, the blocking capacitor can I use different capacitance values between IN1P and IN1N? 

  • 0
    TI__Mastermind 23030 points

    You can use different capacitances on the 2 pins.

    On the INxP  C>1/2*3.14*Fmin*Zin    where Fmin is minimum audio frequency that needs to pass the filter.

    On the INxM line the capacitor is a Bypass and generally brings the pin to a low Impedance for any noise in the system.

    X=1/2*3.14*Fnoise*C.

    A large C helps in creating a more effective bypass for noise even at low frequencies .