I have a use case where I use JTAG debugger connected to the circuit under test. Circuit is powered from a desk PSU and measured via desk MSO. This would normally create a ground loop, so I use an USB isolator ADUM4160 based cheapo device.
Measuring resistance between un-isolated USB "ground" and PSU ground I get around 50+ MΩ. When USB-isolator is connected I am measuring 0Ω with my digital multimeter. Everything works fine, as far as my knowledge reaches.
Now, I want to throw two more USB grounded devices into a loop. Another JTAG debugger for second circuit that will be connected to the first one over serial port (sharing same PSU). Second USB device will be logic analyzer.
- Can I connect USB hub after isolator and connect 3 devices into a hub (that will probably reduce the bandwidth substantially and wouldn't really work)?
- Or do I need USB isolator per device ?
Also, I am running out of USB connections on the PC, so I will need to use the hub.
- Is there any issues connecting multiple isolators to the hub?