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ADS1220: thermocouple

user4971891
Prodigy 10 points
Part Number: ADS1220

I use  thermocouples of type-R to measure the temperature of molten steel. The ADC sampling chip uses ADS1220, which is normal most of the time. However, when the power of the electric furnace for heating molten steel is relatively large, the ADS1220 chip will be disturbed and the measurement result will be abnormal.Below is my circuit diagram:

  • 0
    TI__Guru** 113765 points

    Hi user4971891,

    Interference can come into the system in a variety of ways.  One potential method is through the power supply to the ADS1220.  You want to make sure the supply is stable and that you have bypass caps (100nF) near the AVDD and DVDD supply inputs pins of the ADS1220.

    Also verify that you have a good ground plane as opposed to just ground traces or wires.

    The noise could be entering on the TC wire itself as the wires will act as an antenna.  You may need to add additional filtering on the analog input path. 

    In the end you first need to discover where the noise is actually entering the system and then treat as needed to eliminate or greatly reduce the noise.

    Best regards,

    Bob B