In the process of lightning discharge, due to the strong electromagnetic pulse generated by instantaneous discharge, a surge voltage and current with high amplitude and high rate of change are induced on nearby equipment or electronic circuits, which is devastating to some electronic equipment. The overvoltage/surge protection device is to provide protection for all kinds of electronic equipment, to avoid the electronic components inside the equipment from being damaged by lightning and surge. Varistor, gas discharge tube, TVS tube (transient suppressor diode) three kinds of devices are voltage-limiting surge protection devices, which are all used for surge protection in circuits, but many customers think that TVS diodes Not as good as gas discharge tubes and varistors.
Which of the three components, TVS, pressure sensitive, and discharge tube, is better for lightning strikes?
Only by comparing can highlight the advantages and disadvantages, so as to find the best solution. This trick is applicable regardless of whether it is in the market for investment promotion or the selection of electronic protection devices. But here you can actually see that TVS diodes are inferior to gas discharge tubes and varistors. Many engineers disagree. The engineer analyzed the pros and cons of the three overvoltage/surge protection devices from the three aspects of reaction time, current capacity and working principle, and also deeply let the editor feel the power of TVS diodes, and instantly understand why TVS diodes The scope of application is so wide. The editor does not hide personal information. The following are the three points analyzed by an electronic FAE engineer of the pros and cons of the three types of overvoltage/surge protection devices:
1. In response time
Fast: The response speed of TVS diodes is the fastest, at the picosecond level
Medium: The varistor is between the TVS and the gas discharge tube. The varistor is slightly slower, in the nanosecond level;
Slow: The gas discharge tube is the slowest, usually tens of nanoseconds or more.
Which of the three components, TVS, pressure sensitive, and discharge tube, is better for lightning strikes?
2. On the flow capacity
Small: TVS diodes are usually only a few hundred A;
Medium: The varistor is also between the TVS and the gas discharge tube, and the varistor can pass a single 8/20uS surge current of several KA to tens of KA according to different specifications;
Large: For gas discharge tubes, usually 10 KA level 8/20μS surge current can be conducted hundreds of times.
Which of the three components, TVS, pressure sensitive, and discharge tube, is better for lightning strikes?
3. From the perspective of principle
TVS tube is based on diode avalanche effect;
Varistors are based on the barrier effect between zinc oxide crystal grains;
The gas discharge tube is based on gas breakdown discharge.
Another feature that cannot be ignored is that the diode can be easily integrated with other devices on a chip. There are many devices that integrate EMI filtering and RFI protection with TVS tubes, which not only reduces the number of devices used in the design. Cost, and avoid the accompanying self-inductance that is easily induced when wiring on the PCB.
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