Wi-Fi 6 (802.11ax) launched in 2019 is the next-generation wireless connectivity standard, with a maximum throughput speed up to 9.6 Gbps, and specified to operate in either the 2.4 GHz or 5 GHz frequency bands. Compared with Wi-Fi 5 (802.11ac) used the 5 GHz band exclusively with a top speed of only 6.9 Gbps, Wi-Fi 6 offers significant improvements. In this network information era where people’s routine life is closely related to network, this innovation enables users to experience a faster internet connection.
As the increase in the wireless network transmission rate, the routers featuring Ethernet ports (RJ45) also boost throughput speed from 1 Gbps to 2.5/5/10 Gbps. Since the Ethernet cables are sometimes required to run along the exterior walls, 10 Gigabit Ethernet controller (LAN PHY) is likely to be destroyed by EOS energy through cables by coupling effect. In addition, due to the semiconductor manufacturing process, the 10 Gigabit Ethernet controller is less able to withstand ESD/EOS than a 1 Gigabit controller, which makes the protection of 10 Gigabit Ethernet LAN PHY is relatively important. In this article, the ESD/EOS protection solutions offered by Amazing Microelectronic Corp. for Wi-Fi 6 routers will be introduced.
ESD/EOS protection for 10 Gigabit Ethernet controller can be in line-to-ground and line-to-line modes. The PCB layout with protection circuit is recommended as shown in Figure 1.
Figure 1: PCB Layout with ESD/EOS protection for 2.5/5/10Gbps LAN
The use of 4-channel TVS array for line-to-ground protection against ESD can reduce costs, and the recommended TVS Array to be used is AZ1023-04F with package DFN2510P10E. As for the PCB trace, the Feed-Through wiring can be adopted, which is more convenient. The parasitic capacitance of AZ1023-04F at I/O pin to ground is 0.18 pF (Typ.), protecting against ESD contact discharge at ±8kV and air discharge at ±15kV. The best parameter to qualify the efficiency of an ESD protection is the clamping voltage. The clamping voltage of only 11V can be observed at 16A (ESD 8kV) from the TLP I-V characteristic curve of AZ1023-04F in Figure 2.
Figure 2: TLP I-V characteristic curve of AZ1023-04F
In terms of line-to-line protection against EOS, the AZ5B0S-01F is the latest product developed by Amazing Microelectronic Corp., with DFN0603P2Y as package. Its parasitic capacitance is 0.18pF (Typ.), which can withstand the surge currnet 7A of IEC 61000-4-5 standard. From the I-V characteristic curve of AZ5B0S-01F (Figure 3), it can be observed that the surge clamping voltage is only 4V at Ipp=7A.
Figure 3: Surge clamping voltage on I-V characteristic curve of AZ5B0S-01F
In ESD testing, if the power line of master chip is susceptible to electrostatic discharge, it may result in system crash or even hardware damage during ESD events. In this case, an ESD-protection component shall be added to the power terminal of master chip for clamping protection. The ESD solution of Amazing Microelectronic Corp. for the power line of master chip is to lower the operating voltage to 1.2V, with part No. AZ6112-01F and package DFN1006P2E, which is designed to withstand ESD events up to ±15kV contact. From the TLP I-V characteristic curve of AZ6112-01F (Figure 4), it can be found that the clamping voltage is about 5.5V at 16A (ESD at 8kV).
Figure 4: TLP I-V characteristic curve of AZ6112-01F
Wi-Fi 6 is still the emerging application at the moment, while the master chip manufacturers are continuously developing and upgrading their products. It is recommended to add TVS diodes to circuit application in early stages of the system design to avoid ESD/EOS failure during the testing phase, and prevent the system from any unexpected return for repair caused by damaged Ethernet controller. Please refer the following table and Figure 5 for ESD/EOS protection solutions for Wi-Fi 6 routers.