company news about How to use PTC thermistors for current protection

A PTC (Positive Temperature Coefficient) thermistor can be effectively used for current protection due to its unique resistance-temperature characteristic. Here's how it works:

The Basic Principle:

• At normal operating temperatures, a PTC thermistor exhibits a low resistance, allowing current to flow through the circuit without significant impedance.
• When an overcurrent event occurs, the increased current flow causes the PTC thermistor to heat up due to its internal resistance ($P=I^{2}R$).
• Once the temperature of the PTC thermistor exceeds a specific threshold known as the Curie temperature or switching temperature, its resistance increases dramatically (by several orders of magnitude).
• This sharp increase in resistance limits the current flowing through the circuit to a safe level, protecting downstream components from damage.
• When the fault condition is removed and the PTC thermistor cools down below its switching temperature, its resistance returns to a low value, and the circuit can resume normal operation. This self-resetting behavior is a key advantage of PTC thermistors over traditional fuses.

Applications of PTC Thermistors for Current Protection:

• Motor Protection: Protecting motors from overload and locked rotor conditions.
• Power Supply Protection: Limiting inrush current during startup and protecting against short circuits.
• Battery Protection: Preventing over-discharge and overcurrent in battery packs.
• Loudspeaker Protection: Protecting voice coils from overheating due to excessive power.
• Automotive Electronics: Protecting various circuits in vehicles.
• Telecom Equipment: Protecting against overcurrents in communication lines.
• USB Port Protection: Limiting current to prevent damage to host devices and connected peripherals.

Advantages of Using PTC Thermistors for Current Protection:

• Resettable: They automatically return to a low resistance state after the fault is cleared, eliminating the need for replacement.
• Maintenance-free: Once installed, they generally require no further attention.
• Self-regulating: The resistance increases automatically with temperature/current.
• Can provide both inrush current limiting and overcurrent protection.
• Relatively inexpensive.
• Available in various sizes and specifications.