FEDEVEL
Platform forum

Gobi , 06-26-2025, 10:04 AM

Hi @Robert Feranec

In my application, I am planning to connect the USB shield ground to the enclosure through the standoff.

I have doubts about whether Option B will improve my EMC/EMI performance.

But most of the online app notes recommend having either Option A or Option C.

Please let me know your thoughts.

QDrives , 06-28-2025, 02:13 AM

The endless debate on shielding....

2 'Grounds', 2 location and 3 possible connection methods, it gives you 9 possibilities.
a) No connection
b) Direct connection
c) Capacitor (and resistor)

If we consider that the noise comes from the D+ and D- lines having a capacitive coupling to the shield of the USB cable, you want a connection close the connector so it can return to the source.
In all my (lower speed) designs, 'chassis' was connected directly to Gnd. I did not have EMC problems, but also no USB connection.
https://www.youtube.com/watch?v=Hj-HVve1QC4&pp