Murata PTC Thermistors POSISTOR® for Overheat Sensing

PTC Thermistors POSISTOR® are an electronic component where the resistance remains almost constant near room temperatures. However, when the temperature exceeds a constant temperature, the resistance suddenly increases. Sharp changes in resistance make it possible to accurately detect overheating in multiple areas. "POSISTOR®" is a registered trademark of Murata Manufacturing Co., Ltd.

Exploiting the PTC characteristic (a sharp increase in resistance above a certain temperature), the PRF series chip PTC thermistors are used for overheat sensing in FETs, power ICs, and other heat generating areas.

PRF series = chip type PTC Thermistor for Overheat sensing.
PRF15-1kΩ Series (0402inch size)
PRF15-10kΩ Series (0402inch size)
PRF18-470Ω Series (0603inch size)
PRF18-470Ω Series (Tight Tolerance Type) (0603inch size)
PRF21-470Ω Series (0805inch size)

Features

1. Use of the sharp change in electrical resistance translates into outstanding noise resistance.

2. Sharp changes in resistance make it possible to accurately detect overheating in multiple areas using a very simple circuit connecting PTC thermistors in series.

The distinctive characteristics of "POSISTOR®" can be acquired by adding a small amount of rare earth elements into barium titanate (BaTiO3). Electrodes are formed in ceramics which use barium titanate as the main ingredient to create POSISTOR®, and lead types and chip types are widely used.

Curie Point – The resistance of the POSISTOR® remains almost constant up to a certain temperature, and the resistance suddenly increases after a certain temperature. The changing point of this resistance is called the "Curie point (Curie temperature)", and Murata Manufacturing defines this point as the temperature where the resistance becomes double of the resistance at 25°C.