Jeff,
I have seen this done in systems when there was a separate circuit ground and
chassis ground. In particular these systems had all the mechanical shelf
metalwork, faceplates and faceplate connector shells connected to chassis gnd.
This chassis gnd then ran along the edges of the board making contact to the
metal card guides and terminated on the backplane. On each card plugged into
the shelf chassis gnd was stitched to circuit grounds with capacitors along the
perimeter of the pcb.
If not done correctly these systems suffered from emc issues.
-Bert Simonovich
On Nov 14, 2016, at 5:00 PM, Loyer, Jeff (Redacted sender "jwloyer" for
DMARC) <dmarc-noreply@xxxxxxxxxxxxx> wrote:
I was looking at some designs and found different ground symbols connected by
capacitors. Can anyone explain why this might be done? Everything I've seen
or heard says this is a bad thing (I would connect them directly), but I want
to be sure I'm not missing something. I think there are some A/D devices
which have specific guidelines for separating digital and analog grounds, but
I don't think they'd be connected by caps.
Thanks,
Jeff Loyer
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