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FDC2214EVM: Grounding and shielding

Guoxing Gu
Intellectual 590 points
Part Number: FDC2214EVM

Hello,

 I am testing a FDC2214EVM and going to use it for a prototype. I have questions about its grounding and shielding.

1. There are 2 through holes and 3 U-shape (or call them C-shape) for GND on the board. Do I need to take the ground from a power-outlet and connect it to all of the 5 GNDs when the board is enclosed in a control box?  Or I just need to connect the ground from the power-outlet to any one of the 5GNDs? 

.

2. I use two shielded audio cables to connect  my sensor to the board's INxA and INxB for differential measurement.  Should I also connect the cable shields to the ground from the power-outlet for noise reduction or just let the shields floating?

. 

My lab is in a high building and the only possible earth-ground source is from one of the wall power-outlets.  

Could someone advice?

  • 0
    TI__Genius 17440 points

    Hello,

    1. For prototyping, I think it should be fine to connect only one of the ground points to your system ground.

    2. You can either ground the shield or leave them floating. You can also connect the shields to a buffered version of INxA or INxB if you would like to use active shielding.

    3. You do not need to connect your system to earth ground. We have this application note that discusses the effects of different grounding configurations for the FDC2x1y devices.

    Best Regards,

  • 0 in reply to Kristin Jones93
    Intellectual 590 points

    Hi Kristin, 

    .

    Thank you for your quick reply to my question.

    The application note you provided is an excellent document that addresses grounding and shielding issues. I have been searching for and reading the topics on internet for a long time and believe that this application note is the best one and the most informative one. The note made it easy for common users to understand by including a few different grounding configurations. 

    .

    It might be better if the lines from Cg, Cpg and Cs to earth ground are dashed lines in Figs 2 and 3 of the note. The solid lines imply that they are still earth-grounded. 

    .

    Best regard, 

    Gu