智能烘箱温度控制器设计-英文翻译(6)

compensate the cold end of thermocouple temperature, cold end temperature is around MAX6675 and 0 ℃ temperature difference between the actual reference value. For K type thermocouple, voltage change rate for uv / 41 ℃, voltage by the formula of linear Vout = (uv / 41 ℃) x (tR - tAMB) to approximate characteristics of the thermocouple. On the type of Vout as the thermocouple output voltage (mV), tR is a temperature measurement point; TAMB is ambient temperature.

The cold end compensation: thermocouple function value is the difference in detection of hot and cold side, thermocouple temperature hot nodes may change in the range of 0-1024 ℃. Cold end namely install MAX6675 circuit board surrounding temperature, the temperature changes within the range - 20 - to + 85 ℃. When the cold end temperature fluctuations, MAX6675 still can accurately detect the hot end temperature changes. MAX6675 is through the cold end compensation of the temperature change around the detection and correction. The device is to convert the temperature of the surrounding temperature through internal testing diode voltage temperature compensation, in order to produce practical thermocouple temperature measurement value. MAX6675 from the output of the thermocouple and test measure the voltage at the output of the diode. The inside the diode voltage circuit and the thermocouple voltage to the ADC conversion, to compute the temperature of the hot junction of the thermocouple. When the temperature of the cold end of thermocouple and chip is equal, MAX6675 can obtain the best accuracy of