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PCM1863: Maximum Gain available on PCM1863

George Davies
Prodigy 70 points
Part Number: PCM1863
Other Parts Discussed in Thread: PCM1861, PCM1860

Hello All,

Is the +12dB gain from using Diff ch 2 in addition to the 32dB (26 in diff mode) from the PGA? Also the PGA section (8.8) of the datasheet seems to state the maximum gain is 32dB but the register mapping states 40dB.

For some background, I am interfacing a condenser mic and need as much gain as possible so any suggestions are welcome.

Also does TI have a reference schematic for phantom power to be used with the PCM186x range of devices?

Regards

GD

  • 0
    TI__Guru 57800 points

    Hi, George,

    Welcome to E2E, Thanks for your interest in our products!.

    The gain in the PCM1863 is set with the combination of both Analog and Digital PGAs. This configuration is called automatic gain mapping. in this mode, user can configure the overall gain with register 0x01 and 0x02, then the device will adjust the analog and digital PGAs with the best combination to achieve user's desired gain (i.e. to get 18dB gain, APGA=12dB and DPGA=6dB). In automatic gain mapping mode, the maximum possible gain is 40dB. Manual gain mapping option is also available, however for this device, only analog PGA will determine the overall gain as digital PGA is foxed to 0dB in this mode.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 70 points
    Hi Diego,

    Thanks for the response but this doesn't really answer my main question about the +12dB.

    Do you have any information on that?

    Regards

    G
  • 0 in reply to George Davies
    TI__Guru 57800 points

    Hi, George,

    Thanks for the feedback. I assume your question comes from the data in Table 3. This table is only applicable for hardware controlled devices [PCM1860 and PCM1861] where +12dB gain is the total gain of analog and digital PGA of those parts. These parts have only the option to configure the gain as 0 or 12 dB in differential mode.

    The information I provided is referent to the PCM1863  where the gain can be configured via software.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

     

  • 0 in reply to Diego Melendez
    Prodigy 70 points

    Hi Diego,

    I see thanks very much for clarifying that.

    Regards

    George