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TVS diodes solve the problem of WIFI disconnection in routers due to ESD interference-ASIM
2025.08.25 00:00:00
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Test analysis
In accordance with the IEC61000-4-2 contact discharge ±4K standard. When performing network ping and discharging the external USB metal casing of the router, a WIFI disconnection occurred. Manual reset also fails to connect. It can only be connected after the power is restored. After analysis, it is possible that the main control was affected by ESD interference, causing the system to freeze and resulting in the network disconnection.
Rectification measures
TVS diodes and polymer ESD work together to solve the problem:
Port solution: To prevent ESD from coupling to USB data and power supply lines, connect a high-molecular ESD (model: CV0402VT6030T) in parallel with the corresponding data line to ground and a high-molecular ESD (model: CV0402VT6201T) in parallel with the power supply data line to ground.
Sensitive circuit：
A: USB VCC +5V power supply network
As can be seen from the figure, the VCC +5V network is connected to the USB VCC pin through the main control. If the USB housing is subjected to contact ±4K discharge, it is entirely possible to couple to the power supply line. Therefore, a TVS diode (model: ESD5C150TA) is added to this line for protection.
B：DDR RST network
As can be seen from the network in the figure, one end of the DDR RST network is connected to the power supply line, and at the same time, it is close to the "ground" line. It is completely possible to sense ESD static interference coming to the self-supply line and the "ground". Therefore, a TVS diode (model: ESD3V3C250TA) is also added to this line for protection.
After rectifying according to the above measures, a re-test was conducted. IEC61000-4-2 contact discharge ±4K and air discharge ±8K standard discharge were carried out. The computer network connection was normal and there was no disconnection phenomenon.
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