A resettable chip fuse, also known as a PTC (양의 온도 계수) resettable fuse, is a type of surface mount device (SMD) that protects electronic circuits from overcurrent and overheating. It acts like a traditional fuse but can automatically reset itself after a fault is cleared. When a fault like an overcurrent or short circuit occurs, the fuse’s resistance increases, limiting the current flow. Once the fault is removed and the fuse cools down, its resistance returns to normal, 전류가 다시 흐르도록 허용합니다.
재 정착 가능한 칩 퓨즈 (PPTC) 중합체의 양의 온도 계수 특성에 기초한 과전류 보호 요소입니다.. 자동 재설정 기능이 있으며 전자 장비의 회로 보호에 널리 사용됩니다.. 다음은 핵심 사항입니다:
1. Structure and working principle
Material composition
It is composed of a specially treated polymer resin (such as PE polymer) and conductive particles (carbon black or metal particles). 정상적인 조건에서, the conductive particles form a low-resistance path (0.1-several ohms).
Protection Mechanism
When overcurrent occurs, the thermal effect of the current causes the resin to melt and expand, the conductive network breaks, and the resistance suddenly increases to a high resistance state (up to the megohm level), limiting the current to the microampere level.
After the fault is resolved, the conductive particles cool and shrink, reconnect, and return to a low resistance state, without the need for manual replacement.
PTC Behavior:
Resettable fuses utilize a Polymeric Positive Temperature Coefficient (PPTC) 재료. This material exhibits a significant increase in resistance as temperature rises.
과전류 보호:
When a current exceeds the fuse’s rated value flows, the PPTC material heats up, causing its resistance to increase. This increase in resistance reduces the current flow, preventing damage to the circuit.
자동 재설정:
Once the fault is removed and the fuse cools down, the resistance decreases, allowing normal current flow to resume.
Key Features and Benefits:
Self-Resetting:
The ability to automatically reset after a fault event makes it a reusable alternative to traditional fuses.
과전류 보호:
Protects circuits from damage caused by excessive current, short circuits, or overheating.
Space-Saving:
SMD packaging allows for integration into compact electronic devices.
Wide Range of Applications:
Found in various devices, including computers, 휴대폰, 의료 장비, and automotive electronics.
예:
Imagine a situation where a USB port on a laptop is accidentally short-circuited. A resettable fuse on the USB power line would detect the overcurrent and increase its resistance, limiting the current and preventing damage to the laptop’s power supply and other components. Once the short is removed, the fuse would reset, and the USB port would be ready to use again.