Help with K type thermocouple and AD8495

Thread Starter

FardinBiper

Joined Aug 21, 2012
11
Hello,

I made thermocouple amplifier circuit with the analog devices AD8495.
http://www.analog.com/static/imported-files/data_sheets/AD8494_8495_8496_8497.pdf
There is an application note that tells you how to configure the circuit (figure 6).
http://www.analog.com/library/analogDialogue/archives/44-10/thermocouple.pdf
I made the circuit exactly similar to the app note, however it is giving me incorrect data. The thermocouple sensor is working fine and it can be read by a handheld temperature reader.
On the datasheet it says that if you short out and ground the thermocouple pins, you can read the internal temperature sensor. The goods news is I can do this and the data is accurate.
However when I connect the K type thermocouple I get 4.95V out of the temperature amp which corresponds to above 900 degC.
Please help in way to troubleshoot this circuit.
Thanks
 
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