Low Power Multi-Channel, Thermocouple Measurement System with Cold Junction Compensation

Low Power multi-channel thermocouple Measurement System is a flexible, 4-channel, low power thermocouple measurement circuit with an overall power consumption of less than 8 mW. The circuit has a multiplexed front end, followed by an instrumentation amplifier that performs cold junction compensation and converts thermocouple output to a voltage with a precise scale factor of 5 mV/C. The error is less than 2 C, over a measurement range of -25 C to +400 C and is primarily due to thermocouple nonlinearity. A nonlinearity correction algorithm reduces the error to less than 0.5 C over a 900 C measurement range