Application of TVS diodes in AC and DC circuits

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Application of TVS diodes in AC and DC circuits

Posted Date: 2024-02-07

TVS diodes, the full name is Transient Voltage Suppressors, also known as transient voltage suppression diodes or transient suppression diodes. It is a high-efficiency protection device in the form of a diode, mainly used to protect electrical equipment from voltage spikes introduced by wires.

When the two poles of a TVS diode are impacted by reverse transient high energy, it can change the high impedance between its two poles into low impedance at an extremely fast speed (on the order of about 10 negative 12 seconds), absorbing up to several kilowatts. The surge power clamps the voltage between the two poles at a predetermined value, thereby effectively protecting the precision components in the electronic circuit from damage by various surge pulses.

TVS diodes can be divided into unipolar and bipolar according to polarity. According to their uses, they can be divided into general-purpose devices suitable for various circuits and special-purpose devices suitable for special circuits. Under working conditions, TVS presents a high impedance state to the protected circuit, but when the instantaneous voltage exceeds its breakdown voltage, TVS provides a low-impedance path for the instantaneous current, causing the instantaneous current flowing to the protected component to divert. to the TVS diode, and the voltage across the protected component is limited to the clamping voltage across the TVS.

TVS diodes are protective devices that can quickly absorb circuit surges and can protect downstream circuits. They are available in both unidirectional and bidirectional versions and are suitable for power supply products, communication equipment, household appliances, etc.

Bidirectional TVS diodes are generally used in AC circuits because there are surge voltage impacts in two directions in AC circuits. Its function is to effectively suppress the impact pulses caused in the circuit. Bidirectional TVS diodes are used in AC circuits. When overvoltage occurs in the circuit, the reverse operating voltage will rise to the breakdown voltage and be broken down. At this time, a breakdown current will appear, and when the voltage reaches the peak value, the voltage at both ends of the IPP will be foiled. to below VC. This protects the subsequent components and downstream circuits.

In order to make the circuit safe and reliable in a DC circuit, the maximum reverse working voltage of the TVS tube cannot be less than 1.2 times the circuit input voltage. DC power supplies or other output systems must be connected in parallel with TVS diodes, so unidirectional TVS diodes are often used.

TVS diodes have the characteristics of fast response time and excellent pulse absorption capability. For example, some consumer electronics are very sensitive to electrostatic discharge, so TVS diodes are more widely used in DC circuits than in AC circuits.

What are the application scenarios of TVS diodes?

TVS diodes, or transient voltage suppression diodes, are widely used in various electronic equipment and systems to protect circuits from transient voltages, electrostatic discharge (ESD), lightning, and other forms of overvoltage. The following are some of the main application scenarios of TVS diodes:

Computer systems: TVS diodes are used in computer systems to protect key components such as motherboards, power supplies, interface circuits, etc. to prevent damage caused by overvoltage.

Communication equipment: In communication equipment, TVS diodes are used to protect telephone lines, data lines and antenna interfaces from damage caused by lightning and other electrical noise.

AC/DC power supply: TVS diodes are used in power circuits to absorb surge voltage and protect power transformers, rectifiers, filters and other components from damage.

Automobile: In automobiles, TVS diodes are used to protect automobile electronic control systems, sensors, actuators and other components to prevent failures caused by electrical noise and overvoltage.

Household appliances: In household appliances, TVS diodes are used to protect circuit boards, motors, controllers and other components from damage caused by overvoltage and electrical noise.

Industrial control: In industrial control systems, TVS diodes are used to protect PLC, sensors, actuators and other equipment to ensure stable and reliable operation of the system.

In addition, TVS diodes are also widely used in aerospace, defense, medical and telecommunications fields to provide effective overvoltage protection for various complex circuits and systems.

In practical applications, the appropriate TVS diode type and parameters should be selected according to specific needs and circuit characteristics to ensure the best protection effect.

Review Editor: Huang Fei

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