1.TN power supply systems
Overvoltages caused by human operating errors such as lightning overvoltage waves and load switches can easily invade the interior of electrical and electronic equipment through power supply lines, causing electrical and electronic equipment failure, malfunction, and even permanent damage to the equipment, causing serious economic losses. By installing surge absorbing devices MOV and TVS on the power line, two-level protection is implemented, and common mode and differential mode protection are performed on the L and N lines. The specific method is to install MOV at the front end of the line as the first level SPD protection to discharge most of the lightning current, and install a high-power transient suppression diode (TVS diode) at the end of the line (front end of the equipment) as the second level SPD protection to further weaken the The overvoltage wave amplitude reduces the grid voltage to within the E/I safe withstand voltage range. It should be noted that MOV and TVS should achieve coordination and cooperation of voltage and energy, and the line length between AB should not be less than 5 m. Otherwise, the line length should be increased or decoupling devices should be installed.

2. Network signal lines
Transient suppression diodes (TVS diodes) can not only be used for surge protection of power systems, but also for surge protection of signal lines. Gas discharge tubes GDT and transient suppression diodes (TVS diodes) are combined to form signal surge protection. The device is characterized by fast response, small leakage, almost no signal loss, and can provide safe and reliable protection for high-speed network lines.

3. DC power systems
In the power supply circuit of an ordinary PC computer, the mains AC 220 V is stepped down to AC 20 V through a transformer, and then modulated and rectified by the circuit to output DC 10 V DC power and connected to the load. By installing a bidirectional transient voltage suppressor TVS1 at the output end of the transformer, it absorbs the instantaneous impulse pulse current of the L and N lines and clamps the circuit voltage at a safe voltage level. TVS1 can protect the back-end rectifier and other circuit components of the transformer. A unidirectional transient voltage suppressor TVS2 is installed at the output end of the DC power supply after the rectifier to protect the DC load from overvoltage and current impacts.

4. Transistor circuits
As a current control device, transistors are an important part of electronic integrated circuits. They can be divided into two categories: NPN transistors and PNP transistors [5]. They are used in switching circuits, amplifier circuits and voltage stabilizing circuits. In order to protect the transistor circuit from surge voltage interference such as ESD/EFT (electrostatic discharge/electrical fast transient pulse group), TVS1 and TVS2 are added to the input and output ends of the circuit respectively for protection.

About Semiware
Semiware has a comprehensive product lineup of circuit protection device products. The company leverages its technology in the semiconductor field and application background in end products to serve customers in the electronics, automotive and industrial markets. For more information, please visit semiware official website: https://semiware.com/en/

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