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How do I connect a crystal's ground island to ground plane?

kukaahi

Following a suggestion, I created a ground island around my clock using a solid pour polygon.  The polygon is supposed to be isolated at all points save for a pin on the micro that is both connected to the island ground and the ground plane.  In this example the island is named XT2GND.  Attached are snippets of the polygon in layout, and the schematics of the crystal plus where the crystal connects to the micro from files downloaded from TI.  As you can see in the board layout the highlighted trace is the XT2GND connection to the micro and opposite the trace connecting to the same pin is a trace tying the pin to GND.  The related schematic represents the island being connected to ground via text while the portion of the micro's schematic shows the pin is tied to ground.

 

       

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    Hi Matthew,

     

    Another point to check is the reason for creating a ground plane underneath the crystal.

    Unless there is an explicit reason for this (i.e. the documentation with the IC that you are using, which contains the oscillator circuit that the crystal is part of, tells you to do so, or it is in the evaluation PCB gerber plot) then you very likely shouldn't do this.

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    Hi Matthew,

     

    Another point to check is the reason for creating a ground plane underneath the crystal.

    Unless there is an explicit reason for this (i.e. the documentation with the IC that you are using, which contains the oscillator circuit that the crystal is part of, tells you to do so, or it is in the evaluation PCB gerber plot) then you very likely shouldn't do this.

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