I need to design a universal analog input module .I have referred to CN-0209.But I could not understand the purpose of ADG442 used in the circuit.Can I get help?
The front end will only sample one channel at a time. The procedure would be as follows:
If both channels were thermocouple, the procedure would be similar, though you'd be using he ADG442 switches instead.
If Channel1 was ±10V and Channel2 a thermocouple, then it would be possible to leave Channel 1 connected to the AD8676 and Channel2 connected directly to the AD7193. Then use the AD7193's internal Mux to switch between them.
To support 4-channels there are two options: