thermocouple amplification

Question

hello, i am using t type thermocouples for the measurement. am looking for a instrumentation amplifier for the same. i found ad595 is suit for the this type of thermocouples. but the temperature limit for this one is 0-50 degree celsius. for my application the temperature is 20-100 degree celsius. then i found ad849x for j and k type thermocouples..can i use this for t type?,,also is there any special amplifier for t type for the range of 20-100 degree celsius.. 
 thank you

krisf · Accepted Answer

Hi inayath, 
 T-type and K-type thermocouples require very similar cold-junction compensation voltages. For this reason, I recommend that you use either the AD8495 or AD8497, depending on the ambient temperature range that you are operating at. However, since you are using a T-type thermocouple, your output will differ from the 5mV/degC transfer function mentioned in the datasheet. You can compensate for this by using the NIST method that is on page 2 of this application note . 
 I hope this helps! 
 Kris)

krisf · Answer

Hello inayath, 
 Yes, you can use a multiplexer for your application. You can check this thread for more information. 
 I hope it helps! 
 Kris

krisf · Answer

Hello inayath, 
 Because you are using multiple thermocouples, you also have multiple reference junctions. You can transform these junctions into a single junction by using an isothermal block as in the circuit below: 
 
 There is more information on page 9 of this application note . 
 Does this help? 
 Thanks! 
 Kris

Electronic Design Services - PartnerZone

Products Mentioned

thermocouple amplification