Functions and Applications of Electronic Fuses (eFuses)

A efuse (also called a efuse link) is an electronic component used to protect a circuit from overcurrent or overheating. Its core function is to automatically blow in abnormal situations to cut off the circuit. The following are its key points:
I. Core Principle and Structure

Working Principle

When the current rises abnormally, the conductor heats up due to resistance (following the formula Q=I2RTQ=I2RT), and when it reaches the melting point of the melt material, it melts automatically, thereby cutting off the circuit.

Basic Structure

Melt Material: Lead-antimony alloy (low melting point, high resistivity) was used in the early days, and silver, copper or special alloys are mostly used in modern times.

Packaging Form: Including glass tubular (such as 5×20mm, 6×32mm, 3.6×10mm), ceramic tubular, sheet (for automobiles), SMD patch type, etc.

Overcurrent Protection:
eFuses interrupt the flow of current when it exceeds a predetermined threshold, preventing damage to sensitive electronic components.

Short Circuit Protection:
They quickly detect and interrupt short circuits, which are low-resistance paths that cause excessive current flow.

Overload Protection:
eFuses safeguard against prolonged overcurrent conditions, such as those caused by a mismatched load.

Fault Detection and Isolation:
They can be designed to detect and isolate various fault conditions, including inrush currents, overvoltage, reverse current, and reverse polarity.

Self-Resetting:
Many eFuses can be reset electronically, allowing them to return to normal operation after a fault condition is cleared, eliminating the need for physical replacement.

Adjustable Slew Rate:
Some eFuses offer adjustable slew rates, allowing for control over the speed at which the current rises, which can be useful in preventing damage from inrush currents.

Glass fuse 5×20 single 250/125V fast and slow break 32mA-20A

Inline Fuse 5×20 mm And 1 X 1-4 Inch Quick Fast Glass Fuse

5×20 mm 3 A 3 amp 125 Volt 0.2×0.78 Inch F3AL125V Fast-Blow Glass Fuses

III. ‌Classification and Application Scenarios‌

Type ‌ ‌‌	‌Features ‌ ‌‌	‌Typical applications ‌‌
‌‌Fast-blow type ‌‌	Extremely fast response (<0.001 seconds), used in sensitive circuits	Semiconductor equipment, precision electronic products
‌‌Slow-blow type‌	Allows short-term overload (0.01–0.1 seconds to blow), surge current resistance	Motor starting circuit, power adapter
‌Temperature fuse ‌	Inductive overheating, single-use	Heating appliances such as hair dryers and rice cookers
‌High-voltage fuse	Includes mounting components (such as clamping springs) to simplify pipe connection	High-voltage power system

Applications of Electronic Fuses:
Automotive Electronics:
eFuses are used in various automotive systems, including engine control units, infotainment systems, and safety systems.

Industrial Automation:
They are utilized in programmable logic controllers (PLCs), motor control systems, and other industrial automation equipment.

Consumer Electronics:
eFuses are found in smartphones, laptops, tablets, and other portable devices.

Data Centers:
They are used in power distribution units and server racks to protect critical infrastructure.

Hot-Swap Systems:
eFuses provide protection in systems where components can be added or removed while the system is running.

Battery Management Systems:
They are used in battery charging and discharging circuits to prevent overcurrent and overvoltage conditions.

Power Distribution:
eFuses are used in power distribution units and power supplies to protect against overcurrents and short circuits.

General Circuit Protection:
eFuses can be used in any electronic circuit where overcurrent protection is needed.

6×30, 6.3×32 glass fuse tube fast and slow break 250V/125V 250mA-20A

5×20 ceramic eFuse 00mA 1A 2A 3A 4A 5A 6.3A 8A 10A 12A 15A 16A 20A 25A 30A

Fast Quick Blow Ceramic Fuse 630mA (0.63A) 250V, 5x20mm (3/16 inch x 3/4 inch)

III. Key usage specifications
‌Prohibited substitution of materials‌
Copper wire or iron wire cannot be used as a substitute (low resistivity, high melting point), which may cause an accident due to failure to blow in time.
‌Selection factors‌
‌Rated current‌: It needs to be slightly higher than the maximum working current of the circuit (such as 6A fuse for 5A circuit).
‌Breaking capacity‌: It must be greater than the maximum short-circuit current of the circuit (such as 100A short circuit, ≥100A breaking capacity).
‌Ambient temperature‌: Derating is required for high temperature environment.

Fast-slow, fast-break 6125 chip fuse 20A, 30A, 40A, for new energy battery pack circuit protection

Micro Resistor Type Pico Miniature Cartridge Fuse 250v With Axial Lead Green Fast Acting Fast Blow

6×30 6.35×32 high Voltage Ceramic Fuse Tube 200mA-50A 500V/600V/750/1000V

IV. Technological progress‌
‌Automated detection‌: Such as material transfer components + machine vision detection device, to improve the efficiency of fuse production and sorting.
‌Structural optimization‌: High-voltage fuses adopt a clamping spring design to simplify the installation process.

‌Note‌: After the fuse is blown, it needs to be replaced with a new product of the same specification. For glass tube models, the fuse status can be visually observed to determine whether it is invalid.