NTC is the abbreviation of Negative Temperature Coefficient, which means a negative temperature coefficient. It refers to a semiconductor material or component with a large negative temperature coefficient. The NTC thermistor is a negative temperature coefficient thermistor.
In order to avoid the inrush current generated in the electronic circuit at the moment of power-on, a power type NTC thermistor is connected in series in the power supply circuit, which can effectively suppress the inrush current at the time of starting, and after the suppression of the surge current is completed, Due to the continuous action of its current, the power type NTC thermistor will drop its resistance value to a very small extent due to the temperature rise, and the power consumed by it will be neglected and will not affect the normal operating current, so The use of power-type NTC thermistors in the power supply circuit is the easiest and most effective measure to suppress surges during startup to protect electronic equipment from damage.
PTC is the abbreviation of Positive Temperature Coefficient, which means positive temperature coefficient, which refers to semiconductor material or component with large positive temperature coefficient. Generally speaking, PTC refers to positive temperature coefficient thermistor, PTC thermistor. PTC thermal A resistor is a typical temperature-sensitive semiconductor resistor. When a certain temperature (Curie temperature) is exceeded, its resistance increases stepwise with increasing temperature.
When the circuit works normally, the thermistor temperature is close to room temperature and the resistance is very small. The series connection in the circuit does not hinder the current from passing through; and when the circuit has an overcurrent due to the fault, the thermistor increases the temperature due to the increase of the heating power. When the temperature exceeds the switching temperature, the resistance will increase dramatically and the current in the loop will quickly decrease to a safe value. After the thermistor is operated, the current in the circuit is greatly reduced. Since the polymer ptc thermistor has good designability, it can adjust its sensitivity to temperature by changing its switching temperature (ts). At the same time, it has two functions of over temperature protection and over current protection.