PCB protection devices are mainly divided into several categories.

PCB mainly provides interconnections between electronic components. It is very limited to improve the protection capability of PCB only by optimizing the PCB board wiring. In order to ensure that the whole system has better protection capability of PCB, external PCB protection devices are indispensable. In fact, different PCB protection schemes can be selected according to specific needs. Typical PCB protection devices are mainly in the following categories:

1, clamping diodes. Through two diodes, the transient voltage between positive and negative polarities can be clamped in a certain range, coupled with series resistance to provide power load, so as to play a positive and negative polarity of PCB protection.

2, transient voltage suppressor. Transient voltage suppressor, also known as TVS, is a solid-state diode specially designed for PCB protection. The main feature of TVS is that the response time is short and the leakage current is very small, which is an ideal protection device.

3. Resistance capacitance element. The PCB shielding function can be achieved by accessing resistance capacitance elements on each signal line. Series resistance can suppress the instantaneous peak current, while parallel grounding capacitance can limit the instantaneous peak voltage.

4, voltage stabilizing diode. Although the voltage regulator diode is not specifically designed for PCB applications, its working characteristics determine that it has a certain positive and negative protective effect on PCB. Its disadvantage is that. N-junction is small, so it can not withstand a larger peak current. In addition, it produces a larger parasitic capacitance, which may affect the normal operation of the circuit.

5, gas discharge tube (GDT). The gas discharge tube is made of glass or ceramic with a certain tightness. The tubes are filled with stable gases such as neon or argon to maintain certain insulation. Gas discharge tube has the advantages of high insulation resistance, small parasitic capacitance and self-recovery, but the disadvantage is that the response speed and life are not ideal, and the electrical performance will gradually decay with time.