Table of Contents
What is the working principle of a resettable PTC fuse?
PTC resettable fuses are a step-up from one shot fuses. When a short circuit occurs, they heat up and transition from a low resistance state to a high resistance state. Allowing them to cool down (typically by removing the power) resets them to the low resistance state.
Do resettable fuses wear out?
After a number of trip-reset cycles caused by current or ambient temperature, the PPTC resettable fuse will degrade, and failures will occur.
How do SMD Resettable Fuses work?
Resettable fuses are designed and made of patented novel polymeric PTC material in thin chip form. Upon fault current being removed, the resettable fuse cools and its resistance drops to the original extremely low value. The resettable fuse is “reset” and allows the current through the circuit again.
Where are resettable fuses used?
PolySwitch Resettable PPTC Fuses Ideal for situations where frequent overcurrent conditions occur or constant uptime is required, resettable PPTCs are typically used in consumer electronics, power line, telecom, I/O port, process control and medical equipment protection applications.
When should you use a resettable fuse?
A PTC resettable fuse is a protection device only intended to operate during overcurrent and/or overtemperature events that are not normal operation and are generally undesired conditions. They are not intended to be a switch that operates numerous times in normal operation.
What is a PTC device?
A Positive Temperature Coefficient or PTC Device, is a resettable overcurrent, circuit protection device. It is a series element, made of a conductive polymer that is placed in a circuit. Under normal conditions, the PTC Device has very little resistance, and has little influence on the circuit.
What is a resettable thermal fuse?
A resettable fuse or polymeric positive temperature coefficient device (PPTC) is a passive electronic component used to protect against overcurrent faults in electronic circuits.
How do I choose a resettable fuse?
Select a PTC resettable fuse – based on the maximum ambient temperature and steady-state current. Use thermal derating graphs/ charts. 3. Compare ratings – use an electrical characteristics table, compare the selected device’s maximum ratings with your circuit’s maximum ratings.