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PCM2904: The application question for PCM2904

Mickey Zhang
Genius 12080 points
Part Number: PCM2904

Hi team,

The customer's requirement is as below:

headphone-->USB AUDIO CODEC--->usb speaker

He wants to get the audio signal from the headphone interface of PC, then he needs to output the audio signal through USB.

Can PCM2904 achieve his application?

  • 0
    TI__Guru 57800 points

    Hi, Mickey,

    The PCM2904 is an audio codec which is capable to send/receive audio from a host system through a USB interface. One thing to mention is that tje PCM2904 has some known issues highlighted in this document. A similar device to the PCM2904 is the PCM29906C, which has the mentioned issues fixed.

    For the application you are requesting, it is not clear if the headphone interface is the input or output of the system and if the PCM29xx device is targeted as the interface to capture data from the headphone output and send it to the speaker through USB interface. This approach would require the PCM29xx to act as a host device (as the output is to the USB speaker), which is not a supported mode.

    Can you please provide more information about the signal chain requirements your customer is looking for?.

    Thanks and Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    TI__Genius 12080 points
    Hi Diego,

    The customer needs to capture data from the headphone out. So, as you said, PCM2904 cannot support this mode, correct?

    Would you explain which mode can PCM2904 support in detail? Why PCM2904 cannot be used as a host device(as the output is to the USB speaker)?
  • 0 in reply to Mickey Zhang
    TI__Guru 57800 points

    Hi, Mickey,

    The PCM2904 is a slave USB device and does not have host capabilities. This device is used to interface between analog audio and USB, where a host device can take the USB audio content for playback/record purposes. The operation mode you are targeting is not supported with this device. The only way to use this part on the application mentioned would be to use the PCM to record audio from the headphone, send the USB audio to the host and the host would be able to playback through the USB speaker, which is redundant. Another way to accomplish a similar function would be to use the PCM as the playback device of the host (instead of the headphone) and connect an analog amplifier, this would act as a USB-Speaker system.   

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer