Semiconductor fuse

The electronic fuse a protective device that automatically shuts off a circuit in case of short circuit or overload, and represents a form of overcurrent protection device.

Construction

There are different possibilities to realize an electronic fuse. Depending on the application, various circuit types are used (see example). The fuse is connected to the terminals Uin to the higher supply potential and with U out to the hedged instrument.

In the ground state of the power to the consumer via the transistors V2 and V4 can flow. Since the base -emitter voltages of these two transistors operate in the opposite direction, only a small loss of voltage occurs on these transistors. Nevertheless it requires power transistors to provide the terminal with enough current.

After triggering the circuit can be reset by S1.

Application

Electronic fuses are used in devices that need to be made ​​very compact, must not have any mechanical parts or in which a classic backup using protection diodes or other protective alone are not sufficient, such as in power supplies and power amplifiers ( amplifiers). The electronic fuse also has a much faster response time than about a thermal magnetic circuit breaker or a super fast blow fuse.

In modern appliances finished electronic fuses are installed, which have many additional safety features. These prefabricated components but additionally installed not only in the power supply, but also on the respective board of the actual instrument for the protection capacitor.

Frequently, electronically controlled relay or contactor contacts are referred to as electronic fuse. Ideally, such electro-mechanical contacts, however, are only additionally performed in order to ensure a complete cut-off or a galvanic separation. For switching loads with very high currents up to 100 amperes special high-performance MOSFETs requires no electromechanical contacts, but used.

Electronic Fuses can also be integrated into electronic switches.