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Can I Replace the feedback capacitor?

Jaster Lee
Prodigy 10 points
Other Parts Discussed in Thread: PCM1794, PCM5102A

If IG1&IG2 is DAC Chip PCM1794 Iout(+&-)(RorL),can I replace the feedback capacitor C8&C9&C3 to 100pF or more lesser value?

Beacuse I want let almost no phase shift at 20Hz-22KHz .

C8=C9=C3=2700pF  IG1 to VM1  phase 

C8=C9=C3=100pF  IG1 to VM1  phase 

but i'm not understand have any other effect.  DAC Chip will fine?

The Datasheet of PCM1794 page.20 used 2200pF&2700pF to let fc=217KHz,why? (if analog output to LPF>speaker,theres no human ear can hear)(The LPF or speaker hardware burnt by >217KHz signal?)

The  PCM1794 pin (Iout+&-|L&R) should no output signal at user select sampling rate(more high frequency signal),so even can removal feedback capacitor?

sorry about my poor english

  • 0
    TI__Guru**** 189399 points
    Hi,

    Welcome to e2e, and thanks for your interest in our products.

    I might suggest that you look at one of our newer devices, say PCM5102A for example. It's performance is not quite as good (112 dB vs 132 dB), but usually there is something else in the signal chain that limits the performance.

    You can adjust the filter components in the IV converter circuit about. I assume 217 kHz was set as the corner to result in a flat phase response across the desired audio band.

    -d2