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Original question:

PCM6240-Q1：Problems with DC common-mode difference settings.

PCM6240-Q1: AC coupling capacitor value

Shinji Tsuji
Genius 14119 points
Part Number: PCM6240-Q1

Hi team,

Is there a guide line for selecting the AC coupling capacitor value in AC coupling mode?

regards,

  • 0
    TI__Mastermind 23050 points

    Hi Shinji-san,

    The AC coupling capacitance should be selected based on the desired input HPF cutoff frequency. The effective input impedance depends on bias resistor selection and this is included as part of the AC coupled external resistor calculator. 

    Best,

    Zak 

  • 0 in reply to Zak Kaye
    TI__Genius 14119 points

    Hi Zak,

    If I use the device internal programmable HPF, then how should I consider HPF of external AC coupling cap? 

    regards,

  • 0 in reply to Shinji Tsuji
    TI__Mastermind 23050 points

    Hi Shinji-san,

    I recommend sizing the coupling capacitor much larger than the cutoff frequency desired so that the input coupling caps do not introduce significant amounts of distortion in the audio passband at large signal levels. You can then rely on the programmable HPF to set the cutoff frequency exactly where you want it without introducing this distortion. 

    Best,

    Zak