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XTR101: grounded J-type thermocouple

balazs buglyo
Prodigy 230 points
Part Number: XTR101

Hi Guys,

Let me allow to ask that, can i use Grounded J-type thermocouple for xtr101?
I did not find the answer in the datasheet.

To be honest the best will be the followings: 
Use any type of thermocople , like as grounded or not grounded.


Regards

Balazs 

  • 0
    TI__Expert 5830 points
    Hello Balazs,

    Currently our XTR expert is out for the holidays. I will look into this for you and get back to you with a couple of days.

    Best regards,

    Errol Leon
    Texas Instruments
    Precision Op Amp Applications
  • 0 in reply to Errol Leon6
    TI__Mastermind 23050 points
    Hi Balazs,

    Whether the grounded thermocouple type will work depends a bit on your system and how your grounds are configured. If for example you are probing a liquid that sits in a stainless steel tub (chassy ground), then you need to make sure that the loop supply ground and chassy ground are isolated by a relatively large impedance, or the XTR will fail to regulate properly. You may also need to consider the change in common-mode voltage at the input with the potential difference between the Io pin and whatever you are measuring. If this is an air measurement, then it makes no difference if the probe is grounded or not.

    It is certainly more straightforward to use an ungrounded thermocouple probe, but if you need to use a grounded probe for the response time, then it could be done as long as you are careful to make sure the thermocouple is not shorting the input to loop supply ground.