Thermocouple Circuit Using MCP6V01 and PIC18F2550

This application note shows how to use a difference amplifier system to measure EMF voltage at the cold junction of thermocouple in order to accurately measure temperature at the hot junction. This can be done by using the MCP6V01 auto-zeroed op amp because of its extremely low input offset voltage (VOS) and very high common mode rejection ratio (CMRR). This solution minimizes cost by using resources internal to the PIC18F2550, such as 10-bit ADC and 4-bit adjustable reference, to achieve less than 0.1°C resolution from a measurement range of -100°C to 1000°C.