The Thermocouple Reference Design (TMPSNSRD-TCPL1) demonstrates Microchip’s solution to accurately measure temperature using a Thermocouple and an 18-bit ADC, MCP3421. This solution eliminates the need for the traditional analog instrumentation system calibration or gain and offset trimming techniques. In addition, the Thermocouple linearization techniques can be implemented in firmware or software.

The Thermocouple Reference Design allows user to evaluate Microchip’s solution to accurately measure the temperature. When measuring temperature using a Thermocouple cold junction compensation is critical. It provides a reference to the thermocouple measurement. The MCP9804 provides the cold junction compensation at ±1°C accuracy. If the Thermocouple is compensated using the compensation equation provided by National Institute of Standards and Technology (NIST ITS-90), then temperature can be measured with ±1°C accuracy over the entire measurement range.

The MCP3421 and the MCP9804 serial output lines are connected to a PICMicro Microcontroller. This controller communicates with a PC via the USB interface and commands the ADC to convert voltage. The serial data is then displayed on the PC using the Thermal Management software in stripchart format.