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10G Ethernet ESD/EOS Protection Solution2019/10/04

The development of the present Internet information is at an amazing speed. People can do more and more with the Internet such as online shopping, online movies, online games, and news browsing, etc. Internet has become an indispensable part of people's lives. Terminal systems such as Desk top, Note book, and digital set-top boxes are connected to the network via Ethernet (LAN) ports. The data transmission speed of the Ethernet port is also getting faster and faster with the requirements of Internet connection from the earliest 10M, 100M, 1G to the current 2.5G/5G/10G. Why do we need to increase the transmission speed? The reason lies in audio and video. The resolution of the image is getting higher and higher from 1080p to 4k video. The data transmission of 4k video is very large; therefore, the network transmission speed must be increased to allow viewers to watch online movies more smoothly. The other reason is the Esports games. For Esports games, if the network data is transmitted fast and stable, then it will not change the outcome due to the network connection problem (Lag). The following article will describe the current protection solution for electrostatic discharge (ESD) /electrical overstress (EOS) for Ethernet (LAN) ports.

The main structure of the Ethernet (LAN) port interface is Connector (RJ45) à  Transformerà LAN PHY. For products such as the general Desk top/Notebook/Router, etc., IEC61000-4-2 (ESD) test and IEC61000-4-5 Lightning (Surge) will be conducted on products’ Ethernet (LAN) ports. The main reason is that the Ethernet cable could be installed outside due to the layout requirements. When thundering, the outside cable is easier to sense the surge. The LAN PHY may be damaged due to the surge. Hence, it is especially important to protect the components by adding protection components on the Ethernet port.  

The Ethernet signal with a transmission speed of 1 Gbps or higher is mainly transmitted by 4 pairs of differential signal lines. The protection of ESD and EOS is mainly proposed to be placed between Transformer and LAN PHY, which is called the secondary side (PHY Side). The ESD protection device for 10Gbps Ethernet is AZ1023-04F. The package is DFN2510P10E, which is a four-channel array protection component (TVS Array) that can be applied to high-speed signals. The circuit layout of the PCB is shown in Figure 1. In the PCB circuit layout, the feedthrough can be adopted, which has little influence on the impedance of the PCB, and the capacitance value is only 0.18pF (Typ.). Its ESD protection capability is up to +/-8kV in contact mode and +/-15kV in air mode. The most important parameter for ESD protection components is clamping voltage. From Figure 2, TLP I/V characteristic curve of AZ1023-04F shows that the clamping voltage is about 11V at 16A (ESD 8kV).




Figure 1. AZ1023-04F /AZ1243-04F PCB Layout schematic

Figure 2. AZ1023-04F TLP I/V characteristic curve


The EOS protection solution applied to 10Gbps Ethernet is AZ1243-04F, and its package is also DFN2510P10E. Its PCB circuit layout is feedthrough method, which is the same as that of AZ1023-04F. The capacitance value is 0.5pF (Typ.). Its ESD protection capability is up to +/-25kV in contact mode and +/-27kV in air mode. The characteristic curve of Figure 3. AZ1243-04F shows that the clamping voltage is about 8.5V at 16A (ESD 8kV). In terms of EOS protection capability, it can reach IEC61000-4-5 12A level.



Figure 3. AZ1243-04F TLP I/V characteristic curve


The current ESD (Pin injection 8kV) and EOS (Surge 4kV) test specifications for Ethernet ports are relatively high, and the requirements for ESD/EOS protection components are also relatively high. It is recommended that the Array type TVS is incorporated in the PCB circuit layout design. TVS Array can save PCB space cost and at the same time has the effective performance so as to prevent unnecessary return of products from the markets.




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