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PCM5121: system ground isolation issue

? ?
Prodigy 50 points
Part Number: PCM5121

Tool/software:

hi,team:

     here is an application. if without DC to DC isolation(ground separation). the AUX out noise is big( usb audio don't work).

     my question is if usb audio works , the digital will use the aux path's ground . if this will cause the aux signal noise increase?

     do we have an aux path separation method so the digital and power ground will not disturb the analog audio path ?

     thanks a lot. 

      

  • 0
    TI__Mastermind 30791 points

    Hello,

    Would you explain the problem and question differently, I am not following the question related to the above description.  It seems you have a general question and it is not related to the PCM dac in specific.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    Prodigy 50 points

    hi，

         indeed it's a general question. i didn't find a way to startup a general question Columns. it's related to the audio analog signal quality. i wonder if someone can help find the right columns to startup this question.

        thanks a lot.

  • 0 in reply to ? ?
    TI__Mastermind 46835 points

    Hi,

    Arash is out of office today. He will return tomorrow.

    General questions are okay, but you could provide some extra detail about your scenario and question so that we can understand better?

    Thank you,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Prodigy 50 points

    hi,

        i will describe the question in details: the box speaker has a type-c port and aux in port. the device get power and delivery usb audio to the speaker from the c port. also there is another audio path from the aux port, it's analog out to the speaker. the question is the ground loop from c port to aux port back to the speaker is big thus it can bring up a lot of noise to the aux signal.  i find a solution using TI's cc33410(a dcdc isolation power module) to break the ground loop. but another issue is the case needs usb audio signal back to speaker. the ground is broken. the usb audio signal can't find a reference ground. it must use the aux path's ground,  i suppose this will cause the aux signal becomes bad again.  

  • 0 in reply to ? ?
    TI__Mastermind 30791 points

    In general one might tie several IC's GND to each other and then tie these grounds  at some point together or simply leave it as 2 grounds on the board if that makes sense. ( i.e, GDND and GNDA).

    Regards,

    Arash