Introduction to the Basic Types of Thermistors 3

The p-T characteristic curve of CTR thermistor shows that the temperature dependent characteristics of CTR thermistor are dramatic and have switching characteristics, as shown in the figure. When the temperature is above the Curie point of 4, its resistance value will decrease to a critical state, with a mutation order of 2 to 4. Therefore, this type of thermistor is also known as a critical thermistor. To meet the usage requirements under different conditions, CTR thermistors with different temperature characteristics can be obtained by adjusting the material composition. The figure shows the temperature characteristic curves of CTR thermistors made of different materials. Due to the dramatic temperature characteristics of CTR thermistors, they cannot be used for wide range temperature control like NTC thermistors and can only be used within specific temperature ranges. diode

3. PTC thermistor

PTC thermistor is a semiconductor ceramic component made by sintering barium titanate doped with rare earth elements, with a positive temperature coefficient. Its temperature characteristics are shown in the figure. From the characteristic curve, it can be seen that PTC thermistor components have the following characteristics:

The temperature characteristic curve of some CTR thermistors and the p-T curve of PTC thermistors exhibit semiconductor properties when the temperature is below the Curie point Tc. ② When the temperature is higher than the Curie point Tc, the resistance increases sharply with the increase of temperature, and a negative resistance phenomenon occurs at the TN temperature.

③ It has the characteristic of generating a strong current and then quickly decaying when powered on. Based on the characteristics of PTC thermistors, their self-control function can be utilized to make various thermostats, current limiting protection components, and temperature control switches. They can also be used to form heating elements with PTC thermistors, with power ranging from a few watts to several hundred watts.diode