This circuit can be used to measure exhaust gas temperature in a furnace. The 10-bit LTC1091A gives 0.5Â°C resolution over a ooc to 500Â°C range. The LTC1050 amplifies and filters the thermocouple signal, the LT1025A provides cold junction compensation and the LT1019A provides an accurate reference. The ]-type thermocouple characteristic is linearized digitally inside the MCU.
Linear interpolation between known temperature points spaced 30Â°C apart introduces less than 0.1 oc error. The 20-K/10 KO divider on CHI of the LTC1091 provides low supply voltage detection. Remote location is easy, with data transferred from the MCU to the LTC1091 via the three-wire serial part.