Temperature protection devices are used to protect internal circuits or devices from overheating. The resistance of PTC thermistors rises rapidly when a certain temperature is exceeded, thus stopping the flow of current. This characteristic is self-regulating: Once the PTC cools down, it permits the current to flow again. TDK offers a wide range of PTC thermistors for protection against overload, current surges and excess temperatures. The portfolio also includes SMD NTC thermistors, which act as temperature sensors in monitoring systems. TDK has created the smallest NTC products in the industry by applying the same multilayer technology developed for multilayer ceramic chip capacitors (MLCCs).