I'm working on a portable battery-powered device with a shielded I/O connector for sensors, but I'm confused about how to properly ground the shield and ESD array. Here is a block diagram of my conceptual device:
I'm assuming that grounding the USB connector and it's ESD array to the chassis ground is the right way to go, but should I also ground my I/O connector and it's ESD array to the chassis ground? If the device was running on USB power, the chassis ground would be connected to earth through the host PC. But if the device was running on battery power, the chassis ground would be floating. In this case, should the chassis ground be connected to the system ground somewhere? Wouldn't this cause some of the ground current to flow through the USB cable when it's connected?