PTCtermistorid

PTC thermistorid, also known as positive temperature coefficient thermistors, are a type of thermistor whose resistance increases significantly with increasing temperature. This behavior is due to their semiconductor material composition, which typically involves doped polycrystalline ceramic. Unlike conventional resistors, PTC thermistors exhibit a dramatic and rapid increase in resistance over a specific temperature range, often referred to as the switching temperature. Below this temperature, their resistance is relatively low and changes only slightly with temperature variations. However, once the switching temperature is reached, the resistance can increase by several orders of magnitude.

This unique characteristic makes PTC thermistors ideal for overcurrent protection and self-regulating heating applications. In overcurrent protection, a PTC thermistor acts as a resettable fuse. When a current surge occurs, the thermistor heats up due to the increased current. As its temperature rises above the switching point, its resistance skyrockets, effectively limiting the current flow and protecting the connected circuit. Once the fault is cleared and the device cools down, the resistance returns to its low state, allowing normal operation to resume. In self-regulating heating, PTC thermistors are used to maintain a constant temperature. As the ambient temperature increases, the PTC thermistor's resistance also increases, reducing the power dissipation and thus limiting further temperature rise. Conversely, if the temperature drops, the resistance decreases, increasing power dissipation and warming the object.