5. Design Considerations

1. Ethernet Controller (EMAC)

The emac needs an aditional PHY design. The emac supports both, MII and RMII interface.

Please take care of the specific layout requirements of the Ethernet port when designing a base board. The two signals of the transmitter pair (ETX+ and ETX-) should be routed in parallel (constant distance, e.g. 0.5mm) with no vias on their way to the RJ45-jack. The same is true for the receiver pair (ERX+ and ERX-). No other signals should be crossing or get next to these lines. If a ground plane is used on the base board, it should be omitted in the vicinity of the Ethernet signals.

A 1nF / 2kV capacitor should be connected between board ground and chassis ground (which is usually connected to the shield of the RJ45-jack).