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ADG417 as a thermocouple switch?

Question asked by MariuszPL on Apr 22, 2014
Latest reply on Apr 24, 2014 by EricC



First sorry for my English. I have a problem. In short time I have to make a simple frontend for sapflow sensor. The measuring value will be recorded by datalogger. I have two thermocouplers but only one analog input in datalogger. Unfortunatelly I have limited access to Analog Devices parts. For example there is ADG417 and AD620 at fingertips. Here are my conditions:


-single supply: 5VDC or 12VDC

-logger input voltage range: 0..5V/16bit resolution

-resolution: 10uV (from sensor voltage)

-sampling frequency: one per hour


There are two circuits on pictures below. Please tell me are these circuits correct? I know that sapflow1.png is a worse solution but there is only one AD620. Maybe the ADG417 noise aren't to big to receive 10uV resolution. Which one I should to choose? Maybe some another one?