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PCM2707C: USB host cannot find PCM2707C device

Ben Kuo
Expert 7520 points

Part Number: PCM2707C

Dear Expert,

We design PCM2707C as audio DAC. But now we face an issue, usb host cannot found PCM2707C device.

All the power rail and x'tal are working fine. Schematic as below.

Is there any risk in my schematic? Please give me your feedback about this issue.

Thanks!

  • 0
    TI__Guru 57800 points

    Hi, Ben,

    If the device is properly powered it should be detected by the host as this part uses the native USB Audio driver of the OS. The schematic seems overall ok, however, it seems some resistors in  D+ and D- are missing, are they in a different section of the schematic?.


    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    TI__Expert 7520 points
    Hi Diego,

    Yes, there are one 22-ohm(5%) in each D+ and D-. And there is a USB HUB in the front end.
    I have already check this hub is working fine.
    However, USB host cannot find our device. please give me your suggestion.
    Thanks for your help!

    -Ben
  • 0 in reply to Ben Kuo
    TI__Guru 57800 points

    Hi, Ben,

    Thanks for the feedback. This is not normal, the part should be automatically detected by the host device. Have you tried to bypass the hub to see if the PCM2707C is identified properly by the host system?.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    TI__Expert 7520 points
    Hi Diego,

    Bypass hub can solve this issue. But when we want to set PCM2707C in self-powered mode.
    According to datasheet, Vbus have to connect to VDD with 3.3V DC. After this modification, oscillator desn't work.
    Could you help me to figure out why?

    Thanks!
    Ben
  • 0 in reply to Ben Kuo
    TI__Guru 57800 points

    Hi, Ben,

    As you mention, Vbus should be connected to VDD when the device is set in self-powered mode. You need to make sure PSEL pin is configured to put the part in self-powered mode (PSEL=0) before connecting Vbus to VDD. On the schematic, PSEL = 1, which means the device is set to work in Bus-powered mode.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer