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PCM1803A: Sampling Rate

Akio Ito
Genius 3595 points
Part Number: PCM1803A
Other Parts Discussed in Thread: SRC4392

Hi,

It is described that the sampling rate is 16 kHz to 96 kHz in Features of datasheet top page.
On the other hands, the sampling clock of Digital input clock is 32 kHz to 96 kHz in Recommended Operating Conditions.
Does this mean that the minimum sample rate in master mode is 16 kHz but in slave mode is 32 kHz?

Best regards,

Akio Ito

  • 0
    TI__Mastermind 31655 points

    Hello Ito-san,

    This is a legacy design, and the level of design support we have for this device is limited, so I cannot speak directly to why there is this discrepancy in the recommendations. However, I can test the device at 16khz in the lab. This will really just let us know if the PCM1803A will work at 16khz,  but unless there is an obvious degradation in performance or some other sign, we won't know exactly why it is not recommended.

    Due to a holiday this week it will take some extra time to get this in the lab. I should be able to complete the test by the end of next week.

    Regards,

  • 0 in reply to Scott Cummins
    Genius 3595 points

    Sccot-san,

    Thank you for your reply. I am willing to accept your proposal of cooperation. And I wait for the result of your test.

    Best regards,

    Akio Ito

  • 0 in reply to Akio Ito
    TI__Mastermind 31655 points

    Hi Akio,

    My apologies for the delay. I have not been able to get this into the lab this week as expected. I have some time set aside and will have some results for you by Wednesday July 17.


    Regards,

  • 0 in reply to Scott Cummins
    Genius 3595 points

    Scott-san,

    Thank you for your reply. I am waiting for your test result by July 18th.

    Best regards,

    Akio Ito

  • 0 in reply to Akio Ito
    TI__Mastermind 31655 points

    Hello Ito-san,

    The PCM1803A does seem to be able to function at 16kHz. Unfortunately I can't speak to the reasoning behind the discrepancy between the recommended operating conditions section and the sampling frequency specification from the electrical characteristics table. Do you know what frequency the customer would like to operate at?


    Regards,

  • 0 in reply to Scott Cummins
    Genius 3595 points

    Hello Scott-san,

    Thank you for your sample rate 16 kHz operation testing.
    The customer will use PCM1803A for monitoring a 60 Hz AC line.
    Of cause, we know an industrial ADC is better than PCM1803A for the application.
    The reason why they want to use PCM1803A is they have been using PCM1803A for many their audio products.

    Best regards,

    Akio Ito

  • 0 in reply to Akio Ito
    Genius 3595 points

    Hello, Scott-san,

    As to frequency characteristics of an audio ADC must be determined by mainly the decimation filter.
    Therefor, can we believe that PCM1803A frequency characteristics of 16-kHz sampling are also corresponds with 'DIGITAL FILTER PERFORMANCE' of Electrical Characteristics?

    Best regards,

    Akio Ito

  • 0 in reply to Akio Ito
    TI__Mastermind 31655 points

    Hello Ito-san,

    Are you referring to section 7.7 Electrical Characteristics: Digital Filter from the datasheet? Many of the specifications in that table are defined based on the sampling frequency, so yes they will be based on the 16khz sampling frequency if that is what is chosen.

    Regards,

  • 0 in reply to Scott Cummins
    Genius 3595 points

    Sccot-san,

    As a DEM-DIR1803EVM that was lent to another customer is back recently, I have measured the frequency response of the sample rate 16k and 48k.
    Both sample rates 16k and 48k were measured by converting the sample rate to 88.2k via SRC4392.

    Thanks for your help and support.

    Best regards,

    Akio Ito