POLY-FUSE®, ST Series, PTC Resettable Fuses

PTC Resettable Fuses, also known as polymeric positive temperature coefficient fuses, are specialized components designed to provide overcurrent protection. PTC Resettable Fuses function by increasing their resistance as the current passing through them rises. This increase in resistance is a result of the fuse's temperature rising due to the current flow. As the temperature increases, the resistance of the fuse also increases, eventually reaching a point where it becomes too high to allow the current to flow. This action effectively interrupts the current, protecting the circuit and connected devices. The trip current of PTC Resettable Fuses can vary, typically ranging from 14 mA to 50 A. This range allows for flexibility in choosing the appropriate fuse based on the specific requirements of the circuit being protected. Additionally, the time taken for these fuses to trip can vary, with trip times ranging from as fast as 8 ms to as long as 90 s. This variability in trip time ensures that the fuse responds appropriately to different levels of overcurrent conditions. The term "PTC" stands for Positive Temperature Coefficient, which refers to the characteristic of the material used in these fuses. The material exhibits an increase in resistance as its temperature rises, providing the self-resetting capability of the fuse. Once the overcurrent condition is removed, the PTC Resettable Fuse cools down and its resistance decreases, allowing the current flow to resume. PTC Resettable Fuses are commonly used in various applications that require reliable overcurrent protection. They are particularly beneficial in situations where resetability is desired, as they do not need to be replaced after tripping. This makes them suitable for applications such as automotive electronics, power supplies, battery protection circuits, and more. By incorporating PTC Resettable Fuses into electrical circuits, users can ensure effective overcurrent protection, preventing damage to sensitive components and promoting the safe and reliable operation of the circuit.