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TAC5112: TAC5112 non-standard sample rates

David Whitehouse
Intellectual 260 points

Part Number: TAC5112
Other Parts Discussed in Thread: PUREPATHCONSOLE, TLV320AIC3204

Hello,

I'm looking at the TAC5112 - for our application we need it to run at 125ksps stereo (not a multiple of 48 or 44.1kHz).

  1. The PASI_SAMP_RATE[5:0] option of 128000 (111720-131840) covers this frequency so I assume it can be run at this rate?
  2. The filter responses in the datasheet are all at the "standard frequencies" - how do I tell which filter reponse I will be seeing at this sample rate?
  3. I've put in a request for PurePathConsole - will this make everything obvious?
  4. We've previously run a TLV320AIC3204 at 125kHz and had to use a bi-quad to gain up the channel due to the non-standard sample rate. Is there anything like this I need to think about?

Dave

 

What 

  • 0
    TI__Guru 50230 points

    Hi Dave,

    1. Yes, the semiautomatic mode would cover 125k since it falls in the 128k bin
    2. You will need to choose the sample rate that's closest. If you have very specific needs around the filter response we can work through getting you what you need
    3. Everything you need will be on one page but I wouldn't say it makes it obvious. You'll want to keep that app note handy.
    4. I don't think this would happen on this device

    Best regards,

    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Intellectual 260 points

    Thanks Jeff. On issue 2. the datasheet filters are for (96 or 88.2kHz) and (192 or 176.4kHz) so my 125kHz would be closest to the (96 or 88.2kHz) response - is the semiautomatic mode making that selection for me?

    Kind regards,

    Dave

  • 0 in reply to David Whitehouse
    TI__Guru 50230 points

    Hi David,

    The filters are automatically normalized to the sample rate, so you won't have to do anything to set the interpolation or decimation filters.

    Best regards,
    Jeff McPherson 

  • 0 in reply to Jeff McPherson
    Intellectual 260 points

    Hi Jeff,

    For the linear phase filter:
    Sampling Rate: 96kHz or 88.2kHz - Pass band = Frequency range is 0 to 0.455 × fS
    Sampling Rate: 192kHz or 176.4kHz - Pass band = Frequency range is 0 to 0.223 × fS

    I'm happy the semi-automatic mode for 128000 will latch onto my 125ksps sample rate but I'm still not clear which of the above filter responses the 125ksps sample rate will latch onto? I'm just trying to establish what my passband width will be at 125ksps

    Kind regards,

    Dave 

  • 0 in reply to David Whitehouse
    TI__Guru 50230 points

    Hi David,

    It should latch onto the 0.455 passband performance i.e. more like the 96kHz profile.

    Best regards,
    Jeff McPherson