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ADS1241 for thermocouple measurement

Ryuji
Guru 20090 points
Other Parts Discussed in Thread: ADS1241, ADS1118EVM, ADS1246, ADS1248

Hello,

Please let me know about ADS1241 for single end thermocouple measurement.

Our customer is measuring the many thermocouple voltage, they considering Single end measurement.
Since analog input range become narrowed by the Buffer amp enabled,  we consider to add the bias voltage to the Input signal for adjust the input voltage to Buffer input range. If we apply the 0.05V dc to AINCOM, will the analog input range be "AGND to AVdd-1.495" ?


I couldn't find the information of single end thermocouple measurement.
Are there any application note or concerning for single end thermocouple measurement ?

Best Regards,
Ryuji Asaka

  • 0
    TI__Guru* 97465 points

    Ryuki-san,

    There is an easy way to set the bias point of the thermocouple.

    You can use large resistors on either side of the thermocouple. Tie the positive side to AVDD and the negative side to AGND. A 1MegOhm resistor is a good value. As an example, I have a picture from the ADS1118EVM schematic.

    It's uses two 1 MegOhm resistors to bias the thermocouple at the midpoint between AVDD and AGND. The same can be used for the ADS1241 and keep the thermocouple in the range of the input buffer.

    AINCOM is does not bias the measurement. You can think of it as an another analog input.

    If your customer is still evaluating parts, the ADS1246/7/8 are very good parts for temperature measurement and are quite accurate.

    Joseph Wu

  • 0 in reply to Joseph Wu
    Guru 20090 points

    Hello Jpseph san,

    Thank you for the information.
    I promoted the ADS1248 and the customer selected the ADS1248 instead of ADS1241.

    Best Regards,
    Ryuji Asaka