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Output range problem for AD8497

Hi. I am using AD8497 for K-Type thermocouple measurement. I have given supply of +5v and 0V. and Ref voltage of +0.5V. My input signal ranges from -2.0mV to 70mV. I get output signal only for input signal upto 40mV. Please suggest schematic for measuring the complete range of my input signal.

Below is the schmatic I have used.

Thanks and Regards,

Kumar

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  • Hi Kumar,

    May I know if you were able to make this circuit works and get measurements accurately? The reason Jordyn wants to confirm the 70mV is because for the standard type K-type thermocouple, the 1350°C temperature produces around 54mV as shown on this link. Is it correct to assume that you are sensing temperature higher than 1350°C using K type thermocouple? AD8497 is precision trimmed to optimize a linear operating range for K type thermocouple for measurement temperature range from -25°C to +295°C and ambient temperature of 25°C to 100°C only. For temperature outside this range, implementation of look up table or equation using a microprocessor is needed for nonlinearity correction as discussed on this article.

    Let me know if there something that we could help on your current design.

    Best regards,
    Emman

Reply
  • Hi Kumar,

    May I know if you were able to make this circuit works and get measurements accurately? The reason Jordyn wants to confirm the 70mV is because for the standard type K-type thermocouple, the 1350°C temperature produces around 54mV as shown on this link. Is it correct to assume that you are sensing temperature higher than 1350°C using K type thermocouple? AD8497 is precision trimmed to optimize a linear operating range for K type thermocouple for measurement temperature range from -25°C to +295°C and ambient temperature of 25°C to 100°C only. For temperature outside this range, implementation of look up table or equation using a microprocessor is needed for nonlinearity correction as discussed on this article.

    Let me know if there something that we could help on your current design.

    Best regards,
    Emman

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