Termination Of Unused Differential Signals On Gigabit Magnetics For 10/100 Lom Design; Option 1: Board Level Stuffing; Independent Eeprom Footprints For Individual Lan Controllers - Intel 82541PI Design Manual

Figure 15. Independent EEPROM Footprints for Individual LAN Controllers
4.10 Termination of Unused Differential Signals on Gigabit
Magnetics for 10/100 LOM Design
Since the number of differential signals are different between a 10/100 LAN controller and a
gigabit LAN controller, the two major problems confronted in designing the dual footprint LOM
design are:
1. Choosing the pin compatible magnetics modules for both 10/100 and gigabit controller.
2. Terminating unused differential signals for gigabit between the selected magnetics module and
RJ-45 connector when a 10/100 LAN design is implemented.
The three sections that follow provide the remedies for this issue.
4.10.1

Option 1: Board Level Stuffing

1. Layout resistor footprints on the pairs three and four of the differential traces for 82541PI(ER)
LOM design. Refer to
2. Possibly rework the magnetics module for 10/100 to be footprint compatible with the
magnetics for gigabit.
Application Note (AP-468)
82541PI(ER) and 82562GZ(GX) Dual Footprint LOM Design Guide
Figure 16.
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