Intel 82562EX, Руководство по конструкции

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82540EP/82541(PI/GI/EI) & 82562EZ(EX) Dual Footprint Design Guide
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4.1.11 Traces for Decoupling Capacitors
Traces between decoupling and I/O filter capacitors should be as short and wide as practical. Long
and thin traces are more inductive and would reduce the intended effect of decoupling capacitors.
Also for similar reasons, traces to I/O signals and signal terminations should be as short as
possible. Vias to the decoupling capacitors should be sufficiently large in diameter to decrease
series inductance.
4.1.12 Ground Planes Under the Magnetics Module
The magnetics module chassis or output ground (secondary side of transformer) should be
separated from the digital or input ground (primary side) by a physical separation of 100 mils
minimum. Splitting the ground planes beneath the transformer minimizes noise coupling between
the primary and secondary sides of the transformer and between the adjacent coils in the magnetics.
This arrangement also improves the common mode choke functionality of magnetics module.
Figure 7 illustrates the split plane layout for a discrete magnetics module. Capacitors are used to
interconnect chassis ground and signal ground.
.
Figure 7. Ground Plane Separation
Figure 8 below shows the preferred method for implementing a ground split under an integrated
magnetics module/RJ-45 connector. The capacitor stuffing options (C1 through C6) are used to
reduce/filter high frequency emissions. The value(s) of the capacitor stuffing options may be
different for each board. Experiments will need to be performed to determine which value(s)
provide best EMI performance.
Magnetics Module
Ground Plane
Void or Separate
0.10 Inches Minimum Spacing
Separate Chassis Ground Plane
Gnd_Plane_Sep