User manual

Advantech SOM-Express Design Guide
Chapter 5 Carrier Board Design Guidelines 65
Figure 5-27 and Figure 5-28 shows the 10/100M Ethernet and Gigabit Ethernet
Connections.
Figure 5-27 10/100M Ethernet Connections
SOM-
Express
GBE0_ACT#
LAN Connector
RJ45
GBE0_LINK#
Magnetic
Module
(Transformer)
GBE0_LINK1000#
GBE0_LINK100#
GBE0_MDI[0]+
GBE0_MDI[0]-
GBE0_MDI[1]+
GBE0_MDI[1]-
GBE0_MDI[2]+
GBE0_MDI[2]-
GBE0_MDI[3]+
GBE0_MDI[3]-
Figure 5-28 Gigabit Ethernet Connections
5.7.2.2 Power Considerations and Ethernet LED
In general, any section of traces that are intended for use with high-speed signals
should observe proper termination practices. Many board layouts remove the ground
plane underneath the transformer and the RJ-45 jack to minimize capacitive coupling
of noise between the plane and the external Ethernet cable. Figure 5-29 shows an
example.
Figure 5-29 Ground Plane Separation