There are two main factors to consider when selecting a coupling network: Ethernet data rate and power consumption of the link partner. Table 3-1 shows each Ethernet PHY with the corresponding Ethernet standard and data frequency.

Each coupling network has a maximum current that the network can support while maintaining the required impedance based on the saturation characteristics of the components. Inductors do not behave in an ideal manner, the inductors dissipate heat, pass very high frequencies, and saturate when too much current is passed through. All components and cables have parasitic capacities and inductance throughout the entire circuit. Knowing the maximum power, the link partner draws from the power line and selecting a component design that can deliver that power for a given voltage is important. Calculate the maximum power as the worst-case scenario of power consumption on the link partner side.

Table 3-2 provides coupling network design suggestions. TI recommends selecting one of the networks based on the desired frequency range, current rating, and temperature.