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What are the common electronic circuit protection electronic components?

Published time: 2019-08-22

Electronic circuits are easily damaged in the event of overvoltage, overcurrent, surge, etc. With the development of technology, electronic circuit products are increasingly diversified and complicated, and circuit protection becomes more important. Circuit protection components are also available from simple glass tube fuses to provide a wider variety of protection features.

What is the significance of circuit protection?

In all kinds of electronic products, it is more and more important to set overvoltage protection and overcurrent protection. What is the meaning of circuit protection? Let's talk to you today:

(1) As the integration of circuit boards is getting higher and higher, the price of boards is also rising, so we need to strengthen protection.

(2) For semiconductor devices, the operating voltage of ICs is getting lower and lower, and the purpose of circuit protection is to reduce energy loss, reduce heat generation and prolong service life.

(3) In-vehicle equipment, because the conditions of the use environment are more severe than the general electronic products, the driving conditions of the car are constantly changing, and a large instantaneous peak voltage is generated when the vehicle is started. Therefore, overvoltage protection components are generally used in power adapters for these electronic devices.

(4) Communication equipment and communication places have certain requirements for lightning surge. It is important to use overvoltage protection and overcurrent protection components in these devices. They are the key to ensuring personal safety and communication.

(5) The failure of most electronic products is caused by overvoltage or circuit phenomenon in the circuit of electronic equipment. As our requirements for the quality of electronic equipment are getting higher and higher, the protection of electronic circuits has become more and more negligible. .

Then circuit protection is so important, what are the commonly used circuit protection components? The following will tell you the answer.


(1) Discharge tube

It is used to discharge lightning overcurrent and limit voltage. The voltage is limited to a lower level for protection. It includes a ceramic gas discharge tube and a glass gas discharge tube.

(2) Transient suppression diode

The transient suppression diode can change the high impedance between the two poles to a low impedance at a speed of 10 on the order of minus 12 powers, absorbing up to several kilowatts of surge power, and clamping the voltage between the two poles to a predetermined value. Effectively protects precision components in electronic circuits from various surge pulses.

(3) The role of varistor

The varistor is a voltage-limiting protection device. The circuit protection mainly uses the nonlinear characteristics of the varistor. When an overvoltage occurs between the two poles of the varistor, the varistor can clamp the voltage to a relatively fixed voltage. The voltage value is thus achieved to protect the circuit of the latter stage.

(4) The role of the chip varistor

Chip varistors are primarily used to protect components and circuits from ESD generated in power supply, control, and signal lines.

(5) The role of ESD ESD diodes

The ESD ESD diode is an overvoltage, anti-static protection component designed for I/O port protection in high-speed data transfer applications. ESD protection devices are used to protect sensitive circuits in electronic equipment from ESD (electrostatic discharge). It offers very low capacitance, excellent transmission line pulse (TLP) testing, and IEC6100-4-2 test capability, especially after multi-samples up to 1000, improving the protection of sensitive electronic components.

(6) The role of PTC self-recovering fuse

When the circuit works normally, its resistance is small (the voltage drop is small). When the circuit over-current causes its temperature to rise, the resistance value increases sharply by several orders of magnitude, so that the current in the circuit is reduced below the safe value. This allows the latter circuit to be protected. When the fault is removed, the PPTC component cools down quickly and returns to its original low resistance state, which in turn can be re-worked like a new PPTC component.

(7) The role of inductance

The electromagnetic relationship is believed to be clear to everyone. The function of the inductor is that when the circuit is initially unstable, if there is current flowing through the inductor, an induced current opposite to the current will be generated (Faraday's law of electromagnetic induction). ), after the circuit has been running for a period of time, everything is stable, the current has not changed, and the electromagnetic induction will not generate current. At this time, it will be stable, and there will be no sudden changes, thus ensuring the circuit. Safety, like a waterwheel, started to slow down due to resistance, and then gradually calmed down.

(8) The role of magnetic beads

Magnetic beads have a high electrical resistivity and permeability, which is equivalent to the series connection of resistance and inductance, but both resistance and inductance values vary with frequency. He has better high-frequency filtering characteristics than ordinary inductors and resistive at high frequencies, so it can maintain high impedance over a wide frequency range, thus improving the frequency modulation filtering effect.


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