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TLV320AIC24K: Grounding scheme for audio codec

Archana Rao
Intellectual 915 points
Part Number: TLV320AIC24K

Hi, 

We are using three TLV320AIC24KIPFBG4 audio codecs in cascaded mode on our board with microphone input and 150 ohms audio outputs.

We are referencing these audio codecs to digital ground since we do not have separate analog ground on the board. 

 

We cannot meet the datasheet recommendation (as shown in below snapshot) on our board. 

  • Is it necessary to keep two separate grounds (AGND and DGND) for this codec?
  • What would be the impact of referencing audio codec to digital ground considering that there is no possibility of having a separate analog ground?

 

Awaiting for your response.

Regards,

Archana Rao

  • 0
    TI__Mastermind 22950 points

    Hello Archana,

    I did not see an attached picture. Can you please resend this?

    Connecting AGND pin to DGND plane directly may cause some external noise to be introduced as DGND is usually the more noisy of the two. Ideally, the AGND and DGND ground planes should be separated on the board and should be shorted at only one place as close to TLV320AIC2x as possible. 

    Regards,

    Aaron

  • 0 in reply to Aaron Estrada
    Intellectual 915 points

    Thank you for your reply, Aaron!

    Please see the image below,

    What would be the impact on analog codec operation if DGND noise gets coupled to it?

    Since, we have no provision of AGND on board, we are forced to reference audio codec to DGND.  We really need clarification on this perspective for the deviation taken.

    Regards,

    Archana Rao

  • 0 in reply to Archana Rao
    TI__Mastermind 22950 points

    Hello Archana,

    Sure thing! It is honestly hard to say exactly what the impact will be. Ultimately, noise from DGND can get coupled in the analog portion and make it's way to the analog inputs of the device and degrade performance. 

    In order to prevent this, we highly recommend following data sheet recommendations. 


    Regards,
    Aaron