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Original question:

PCM1794: Which digital input decides PCM1794 sampling timing?

PCM1794: Questions about PCM1794A THD+N spec

Will Wang47
Expert 5510 points
Part Number: PCM1794

Hi team,

Customer using PCM1794A, and they have following question about this part:

1. Datasheet P6 shows the following THD+N result, test condition is 0dB, what is the voltage of 0dB?

2. What's the test frequency of this THD+N spec?

3. Customer see THD+N are different under different fs, however, customer didn't see a much difference, do you have any more comments?

Thanks and best regards,

Will

  • 0
    TI__Guru 52683 points

    Hi Will,

    1. 0dB means that we have a full scale output, which is 4.5VRMS for that portion of the table:

    2. We generally test THD+N with a 1kHz input signal.

    3. Is the THD+N acceptable from their measurements? I would expect a slight increase in THD+N as sample rate goes up, but these are also typical values and can vary.  The external filter also can impact this as it can remove more of the out-of-band noise.

    Thanks,

    Paul