Thermal protection PTC thermistor

General

Making use of the characteristics that the resistance of PTC thermistor increases sharply above curie temperature, when ambient temperature increases abnormally, protective circuit with PTC thermistor installed will turn on or cut off loop through resistance changing, achieving protection purpose.

Main parameters

Protection temperature point TS（℃）
Rated zero power resistance R25(Ω)
Resistance at protection temperature
Resistance at protection temperature--15℃ （RS-15，Max）

Operating principle

As in fig. 1, in normal ambient temperature, PTC thermistor resistance Rp<Rs, lower output voltage. When ambient temperature exceeds set temperature, PTC thermistor resistance Rp increases rapidly, and exceeds Rs，and leads Vo increases to high enough voltage, and cause tripping.

fig.1　　　　　　　　　　　　　　　　　　　　　　　　fig.2

Application example