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PCM1789-Q1: TAS5421QPWP &PCM1789TPW

AGXIN
Intellectual 510 points
Part Number: PCM1789-Q1
Other Parts Discussed in Thread: TLV320ADC3101, PCM1789

Hi Team

we are using this DAC part in our design All the digital signals are driven from the processor to the DAC and the DAC is interfaced to the PA TAS5421QPWP. Generally, we separate the And and Dgnd in DAC 

if we need to do we should connect the DGND to the digital GND but in the datasheet, both are connected to a common AGND Can I connect this DGND pin to the Digital GND Since VDD is connected to the digital supply if the analog audio outputs are connected to TAS5421QPWP Which ground should this Use 

This is the Current schematics that we have 

  • 0
    Intellectual 510 points

    If we modify the schematics both the AGND And DGND will be separated through Inductance so that we have a separation between GND and at the same time return path will also get established Please confirm 

  • 0 in reply to AGXIN
    TI__Guru 53183 points
    Hi AGXIN,

    You updated schematic looks okay to me. I think this is good separation of the DGND and AGND. Note that separating the grounds is a good way to force you separate the design into a analog domain and digital domain, but component placement is still critical. If you are space limited on the PCB, and you cannot geographically separate the analog and digital components, it is better to have a single unified ground.

    Thanks!
    Paul
  • 0 in reply to Paul_Frost
    Intellectual 510 points

    Hi 

    what is the impedance to be followed for the mic and speaker signals when using

    1)PCM1789-Q1: TAS5421QPWP

    2)TLV320ADC3101

  • 0 in reply to AGXIN
    TI__Guru 53183 points

    Hi AGXIN,

    The PCM1789 minimum impedance for an DC coupled path to ground is 15kohm.

    I am not quite sure about the impedance for the MIC, though I think it would really be dependent on the MIC rather than the ADC.

    Thanks!

    Paul