I'm working with the ADG507A Multiplexer. I currently have it set according to the schematic:
The output goes to an AD595 Thermocouple Amplifier, and the input connects to a grounded thermocouple. The AD595 requires a connection to ground from the thermocouple, which forces the 1Mohm resistor from the thermocouple to the power supply common.
We have had some concern that the digital ground could inject noise through the analog input to anything on the other end. So we are considering isolating the power supply common and the inputs from the digital ground and the IC ground, like the following schematic:
Can the ADG507A operate in this configuration? Or does it require a reference to the power supply common?
Sorry about the delay of the reply. The GND of the device should be connected to the ground of the power supply and the digital logic as both are reference to GND within the device.