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PCM1863: How fast does the audio bandwidth on the main ADCs roll off?

Cynthia Cantrell
Prodigy 50 points
Part Number: PCM1863
Other Parts Discussed in Thread: PCM1862, PCM1861, PCM1860, PCM1865, PCM1864

Page 46 of the PCM 186x datasheet enlightens us with this useful tidbit of information:

"9.3.10.1 Main Audio ADCs


The SNR of the primary ADCs in the PCM186x are 103 dB (for PCM1860, PCM1862, PCM1864), or 110 dB (for PCM1861, PCM1863, PCM1865), with 40-kHz bandwidth that is tightly coupled to dedicated PGAs and input multiplexers."

It would be VERY helpful for me to know what the rolloff for this filter is - 6dB/octave? 12dB/octave? Worse? Can you give me any idea of the tolerance on this as well?

Does the secondary ADC have a similar (40kHz) bandwidth, or is it closer to the 10kHz listed for the Energysense signal on page 13?

Thank you,

Cynthia

  • 0
    TI__Guru 57800 points

    Hi, Cynthia,

    The data you are asking about actually is not specified for this device, let me check with my team and see if we can pull this information. As this part was designed by a team which is no longer in TI, it may be difficult to get the actual specs and it may take some time before we find something, so I appreciate your comprehension.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 50 points

    Hi Diego,

    After looking at the data sheet some more, I'm wondering if the "40-kHz bandwidth" might refer to the bandwidth used to measure the SNR spec, and not the bandwidth of the primary ADCs.  Unfortunately there aren't any plots or other info that might clarify this.  

    Figure 19 has 192kHz THD info going out to 60kHz, but to determine what I need to know, I'd like to see a 90kHz input signal make it all the way through the ADC and show up at 90kHz on the FFT and see that it is NOT attenuated significantly.

    Thank you for checking into this!

    Cynthia