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PCM2903: The PCM2903 circuit question

Part Number: PCM2903

Hi team,

My customer is using the PCM2903 now. And we want to check why we use the circuit in the circuit, could you please help explain it?

Can we just connect D+ to VDD? If we cannot, could you please help explain it?


  • Hi, Frank,

    The PCM2903C is a self-powered USB-Audio codec, this means that it requires a power supply different to Vbus to power-up the device. The purpose of IC1 in the schematics is to make sure D+ is pulled high until both USB Vbus and VCC are powered. This is done to ensure the correct operation of the device.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer