Midea 22031010000841, Service Manual

Page: 34 / 47

Service Manual , 2016-12
34 / 47
10.3 Temperature test circuit
The characteristic that resistance value reduces as the temperature increases is deemed to have
negative slope or negative temperature coefficient (NTC), and such thermistor is called as NTC
thermistor. The resistance value changes sensitively with temperature and typically changes 7% ~
3% per degree centigrade. Sensor used in the refrigerator is NTC thermistor.
There is following computing formula for the sensor:Sampling voltage / reference
voltage = R1 / (RNTC + R1)
AD value / reference AD value = R1 / (RNTC + R1)
The reference voltage is 5V, RNTC is the resistance value of the sensor, R1 is R31\R32\R33 in
schematic diagram that is 5.1K