• State Resolved
  • Locked Locked
  • Replies 8 replies
  • Subscribers 31 subscribers
  • Views 530 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

PCM4202 / internal connection of GND pins

S.Satoshi
Guru 21685 points
Other Parts Discussed in Thread: PCM4202

Hi,

Now our customer start to draw PCB layout with PCM4202 then they have two question and request. Can you please give your advice?

1, Are the GND pins (AGND/AGNDL/AGNDR) connected internally?

2, Can you please give your advice for key care about for GND layout? And please let us know the reason to care if we need to care.

Best Regards,

Sonoki / Japan disty

  • 0
    TI__Genius 16270 points

    Satoshi-san,

    1)  For most of the converters these pins are connected internally, but each of these pins should still be connected externally to the GND plane to minimize any loops. 

    2)  For GND Layout, try to use solid , separate GND planes for digital and analog grounds that are isolated from one another.  But then connect these GNDs underneath the device itself.  This minimizes the chance for long GND current loops to cause GND noise that can corrupt SNR.  For any decoupling capacitors, please also place them as close to the device as possible, so that no stray inductances are caused which can also lead to noisier output.  For decoupling capacitors, also avoid vias if possible and keep them on the top layer, as vias can induce some stray inductance. 

  • 0 in reply to Patrick Galvin
    TI__Guru**** 189401 points

    Hi, Sonoki,

    As always, I highly recommend that customers always copy our EVM designs as closely as possible. 

    I noticed we didn't post the Gerber files for this EVM, while I get that fixed, do you need me to post them here for you?

    -d2

  • 0 in reply to Patrick Galvin
    Guru 21685 points

    Hi Patrick-san,

    Thank you for your response.

    I understand that the converters included PCM4202 have internally connected GND.

    And I also inform our customer the layout guideline for grounding you recommended.

    Best Regards,

    Sonoki

  • 0 in reply to Don Dapkus
    Guru 21685 points

    Hi, Don-san

    I believe that the drawing of layout pattern in user's guide will be enough to our customer to refer recommended layout. I will ask you if they hope to have the Gerber files.

    Best Regards,

    Sonoki

  • 0 in reply to S.Satoshi
    TI__Guru**** 189401 points

    OK, Sonoki, great!

    Please start a new thread if you want the gerber files. I am going to close out this one.

    -d2

  • 0 in reply to Don Dapkus
    Guru 21685 points

    Hi, Patrick-san,

    I heard that the DGND, AGND, AGNDL and AGNDR of PCM4202 are connected internally, but the customer measured the impedance between these GND pins of device before mounting and then they confirmed they are almost isolated (1M~2Mohm). Can you please check again if they are isolated or not?

    Best Regards,

    Sonoki

  • 0 in reply to S.Satoshi
    TI__Genius 16270 points

    Satoshi-san,

    These pins must still be connected to the same GND potential, even if they are internally isolated.

  • 0 in reply to Patrick Galvin
    Guru 21685 points

    Hi Patrik-san

    Thank you for your response. I heard that the most of the converters these pins are connected internally but I make changes our answer as you commented again.


    Best Regards,

    Sonoki