USB jac grounding and USB measurement

[Evan Shultz]

Hi guys.

I have made a USB DAC using the TI PCM2702 IC with great results. However, I haven't ever grounded the shield, just the ground pin. In case I am not being clear, I have the the mounting tabs of the USB jack floating. Should it be grounded? Or perhaps grounded through a bead? Thank you.

While I'm on the subject, does anyone have ideas of how to get measurement signals, specifically an Audio Precision output, in USB format so I can measure the DAC's performance?

 

[Evan Shultz]

I notice it isn't grounded on the TI reference board nor the PCM2702 board produced by 00940.

 

[00940]

I notice it isn't grounded on the TI reference board nor the PCM2702 board produced by 00940.

To be honnest with you, there's only one reason for that : it wasn't grounded in the Eagle's library 😉

 

[fluckscapacitor]

I'm also interested in what is the proper grounding for the USB connector shield at the receiving end

 

[guzzler]

It's not really necessary from an electrical point of view, but it is much better mechanically as there is quite a lot of force involved in removing/inserting the USB plug. I've got modified Eagle libraries with this done. Please EMAIL if you'd like a copy.