What is the function of the thermistor in the charger?
October 10, 2021
There are generally two functions of thermistor in the charger: one is placed on the input end, generally a thermistor is connected in series after the fuse is rectified. Its function is to prevent the effect of excessive inrush current. Generally, there will be a large inrush current when the power is turned on. Excessive inrush current may damage other components. After the heating-sensitive resistor, the resistor can absorb the instantaneous inrush current and save its energy. Absorption is transformed into heat energy. When the circuit works normally, the thermistor becomes hot and its resistance decreases.
At this time, it can be regarded as a short-circuit state and does not affect normal operation.
This thermistor is generally not too small, with a diameter of at least 8mm or more. The other is to place the thermistor on the hot element for over-temperature protection. When the temperature is too high somewhere, the resistance of the thermistor will decrease. Cooperate with IC control output capability for over-temperature protection. However, the first case is more common. The probability that you are asking belongs to the first case. After all, most of the chargers of electric vehicles still seem to be very rough, and the over-temperature protection function should not be used.