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PCM2906C: Windows &

Yuriy Lapushev
Prodigy 140 points
Part Number: PCM2906C

Hi!

I have some problem with my ADC in Windows 7.

I have built PCM2906 based audio ADC (there is the board schematic in the attachment).

It's works fine but in first three-five minutes. After this device is switching off and new USB device connection is possible only after windows restart.

What could be wrong? Help, please!

Thanks for your answer!

  • 0
    TI__Guru 57800 points

    Hello Yuriy,

    Thanks for the post. It seems there is nothing strange with the PCM2906C part of the schematic, from your previous thread it seems that if VCOM voltage is decreasing after the issue occurs there could be a problem with the internal regulator. Can you please also monitor VCCCI when the problem happens?. Also, have you noticed a weird behavior before the issue occurs, like output signal saturation or noise?

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 140 points
    Hello, Diego?
    Thanks for reply!
    Vccci is OK, but Vconlm, that must be ½Vccci is 0.69V.
    Is it necessary to use external reference voltage regulator in my case?
    Thanks very much!
  • 0 in reply to Yuriy Lapushev
    TI__Guru 57800 points

    Hi, Yuriy,

    Thanks for the feedback. Based on this, the problem could be that the internal VCCCI for VCOM is damaged. I would recommend you to try a different IC to identify if the issue is related to an specific device malfunction. This device is bus powered, so an external regulator can't be used. 

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 140 points

    Hi, Diego!

    thanks for reply and help!

    It will take some time to try new IC, because it's necessary to buy it in USA).

    But what about standart application schematic (in attachment) from datasheet, where Vccci is powered from external reference voltage source?

    Thanks very much!

  • 0 in reply to Yuriy Lapushev
    TI__Guru 57800 points

    Hi, Yuriy,

    The voltage regulator can be used to operate the device in high performance mode. For this case, you need to power up VCCCI with an external regulator. I assumed you are targeting a fully-bus powered application where regulator should not be used, sorry for the misunderstanding.

    However, if the IC has any damage in the internal regulator circuitry, the use of an external regulator might not help.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 140 points
    Hi, Diego!

    Thanks for reply!
    I'll try to use new IC.

    Thaks very much!