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PCM2903C:Circuit Design

Anand
Intellectual 540 points
Other Parts Discussed in Thread: PCM2903C, DRV603

Hi,

We would like to use PCM2903C audio codec chip in our design where the codec chip is interfaced with on-board host processor.

The design requirement is converting digital audio data(from host processor)via USB into analog audio output.

I have seen application circuit.I need some clarifications on that

* Analog & Digital power pins can be sourced from single common supply or do i need to isolate analog and digital voltages

* Whats the purpose of using 1 Mohm resistor pulling down to ground for Vbus line ?

* Any recommendation for unused pins since we have many pins that are not used in our current application.

  • 0
    TI__Guru 57800 points

    Hi, Anand,

    The same voltage source can be used for both Vdd and Vcc, in general, isolating analog from digital power supplies is a good practice to avoid digital noise to couple to analog sections of the device. The 1MΩ resistor is required for the proper detection of Vbus by SEL1 pin. and is required for the self-powered operation of this device. In general, you can leave floating the analog outputs and unused HID pins, for unused analog inputs, it is recommended to connect them to ground with a decoupling capacitor.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Intellectual 540 points
    Hi Deogo,

    Thaks for the reply,

    I saw in datasheet regarding analog output specification saying p-p voltage is 0.6VCC and center voltage 0.5Vcc.
    Does it mean i ll have voltage swing of 0.6VCC centered at 0.5VCC voltage ?
  • 0 in reply to Anand
    TI__Guru 57800 points

    Hi, Anand,

    Correct, the output of the device will have a full-scale voltage of 0.6×Vccc Vpp centered at 0.5×Vccc V.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Intellectual 540 points
    Hi Diego,

    Thanks for the clarifications.

    I'm working on this Audio codec design and my customer needs 9Vp-p audio analog output with 600ohm line impedance.
    Can you suggest me any dual channel audio amplifier which could meet the above requirement.
  • 0 in reply to Anand
    TI__Guru** 109395 points
    Hi Anand,

    Let me comment about your last post.
    You can use DRV603 line driver. This device features an internal charge pump, so you would need to supply it with at least 5V on PVDD so it can go up to 9Vp-p at the output without clipping.
    Hope this helps. Please let me know if you need further support on this.

    Best regards,
    -Ivan Salazar
    Audio Applications Engineer - Low Power Audio & Actuators
  • 0 in reply to Ivan Salazar
    Intellectual 540 points
    Hi Ivan,

    I also thought of using this,but our customer insisting to use operational amplifier instead of this line driver .So It would be more helpful if you can suggest me any dual channel opamp.
  • 0 in reply to Anand
    TI__Guru** 109395 points
    Anand,

    I think some amplifiers form OPA16xx series could be an option.
    However you can make a new post on general purpose amps forum for a specific suggestion: e2e.ti.com/.../

    Best regards,
    -Ivan Salazar
    Audio Applications Engineer - Low Power Audio & Actuators