PTC Resettable Fuses are designed to stop current flow when it exceeds a certain limit (overcurrent protection). The Fuses work by increasing its resistance as its temperature rises due to the current increase. The trip current ranges from 14 mA to 50 A with the Time to trip ranging from 8 ms to 90 s. PTC = Positive Temperature Coefficient.
PTC Resettable Fuses, also known as Polymer Positive Temperature Coefficient (PPTC) devices, are a type of circuit protection component designed to protect electrical circuits from overcurrent conditions. Unlike traditional fuses that need replacement after a fault, PTC resettable fuses automatically reset after the fault is cleared. They operate by increasing their resistance dramatically when the current exceeds a certain threshold, thereby limiting the current flow and protecting the circuit. Once the fault condition is removed, the device cools down and returns to its low-resistance state, ready to protect the circuit again.
Types of PTC Resettable Fuses
Surface Mount Devices (SMD)
SMD PTC resettable fuses are designed for compact and high-density circuit boards. They are commonly used in consumer electronics due to their small size and ease of integration into automated assembly processes. These fuses are ideal for applications where space is a premium and where automated assembly is preferred.
Radial Leaded Devices
Radial leaded PTC fuses are typically used in applications where higher current ratings are required. They are characterized by their two protruding leads, which make them suitable for through-hole mounting. These fuses are often found in power supplies, transformers, and other high-current applications.
Axial Leaded Devices
Axial leaded PTC fuses are similar to radial leaded devices but have leads extending from each end of the cylindrical body. They are used in applications where the fuse needs to be mounted in-line with the circuit. These fuses are often used in automotive and industrial applications where robust and reliable protection is necessary.
How to choose PTC Resettable Fuses?
When selecting a PTC resettable fuse, several key parameters should be considered:
Hold Current (Ihold): The maximum current the device can conduct without tripping.
Trip Current (Itrip): The minimum current at which the device will transition to a high-resistance state.
Voltage Rating: The maximum voltage the device can withstand without damage.
Resistance: The initial resistance of the device in its low-resistance state.
Time to Trip: The time it takes for the device to transition to a high-resistance state once the trip current is exceeded.
Evaluating product quality involves checking the manufacturer's reputation, certifications, and compliance with industry standards. Environmental factors such as temperature range and humidity should also be considered, as they can affect the performance of the PTC fuse. Installation requirements, such as mounting style and space constraints, should be taken into account to ensure proper integration into the circuit design.
Applications of PTC Resettable Fuses
Consumer Electronics
In consumer electronics, PTC resettable fuses are used to protect devices such as smartphones, tablets, and laptops from overcurrent conditions. They ensure the safety and longevity of these devices by preventing damage from power surges and short circuits.
Automotive Industry
PTC resettable fuses are employed in automotive applications to protect electrical systems such as infotainment systems, power windows, and seat controls. They provide reliable protection against overcurrent conditions, ensuring the safety and functionality of the vehicle's electrical components.
Telecommunications
In telecommunications, PTC resettable fuses are used to protect network equipment, such as routers and switches, from overcurrent conditions. They help maintain network reliability and prevent downtime by safeguarding critical communication infrastructure.
Industrial Equipment
Industrial equipment often requires robust circuit protection due to the high currents and harsh environments in which they operate. PTC resettable fuses are used to protect motors, transformers, and control systems from overcurrent conditions, ensuring operational safety and efficiency.
Medical Devices
In the medical field, PTC resettable fuses are used to protect sensitive equipment such as diagnostic machines and patient monitoring systems. They provide reliable circuit protection, ensuring the safety and accuracy of medical devices critical to patient care.
