how to suppress the damage of transient voltages and surges to electronic diodes

As we all know, electronic diodes will encounter unexpected voltage transients and surges during use, resulting in damage to electronic products, mostly semiconductor devices (including diodes, transistors, thyristors and integrated circuits) in electronic products are burned or broken down. A transient voltage surge is a spike pulse with a high rising speed and a very short duration. There are many causes of voltage transients and surges: static electricity, switching ignition, grid overvoltage, motor/power supply noise, reverse source, etc.

So, the key question is, how to suppress the threat and damage of transient voltages and surges to electronic products? The next class explains five protection methods against transient voltages and surges.

1) The whole machine and the system grounding: the whole machine and the system of the ground and the earth separated, the whole machine and the system of each subsystem should have an independent common end, in the subsystem to transmit data or signals, should be the earth as the reference level, the grounding wire must be able to flow through a large current, such as hundreds of amperes.

2) The key parts of the whole machine and the system use voltage transient and surge protection devices (TVS diodes, varistors, ceramic gas discharge tubes, etc.) to bypass the subsystem ground and the ground, so that the transient voltage and surge amplitude entering the whole machine and system are greatly reduced.

3) For important and expensive machines and systems, several voltage transient and surge protection devices are combined to form a multi-level protection circuit. Generally, varistors and ceramic gas discharge tubes are used as protection, and TVS diodes are used as secondary or secondary protection.

4) In order to strengthen the protection effect of electronic products, an ultra-isolated transformer (also known as isolation method) can be connected between the power supply and the load to isolate high-frequency spike interference, and at the same time, the secondary equipotential connection can be easily carried out.

5) The absorption method mainly uses surge protection devices to absorb the surge surge interference voltage. Surge protection devices have a common feature, that is, high impedance below the threshold voltage, and once the threshold voltage is exceeded, the impedance drops sharply, so it has a certain suppression effect on the peak voltage.

Such surge protection devices mainly include varistors, gas discharge TVS diodes, TVS diodes, solid discharge tubes, etc. Different surge protection devices also have their own advantages and limitations in suppressing voltage spikes. For example, the TVS diode flux is not large enough, the current absorption capacity of the varistor is not large enough, and the response speed of the gas discharge TVS diodes is slow!