82541PI(ER) and 82562GZ(GX) Dual Footprint LOM Design Guide
Application Note (AP-468)
35
Figure 9. Ideal Ground Split Implementation (for Integrated RJ-45 without USB)
The table below gives some starting values for these capacitors.
The placement of C1 – C6 may also be different for each PCB design. For example, all capacitors
might not need to be populated). Also, the capacitors may not be needed on both sides of the
magnetic module.
Systems with integrated USB ports on the magnetics module might have difficulty using a chassis
ground configuration due to the need to get DC ground to certain USB pins. One technique is to
fabricate an incomplete ground split (partially open on one end). By connecting the ground planes
around the RJ magnetics module through a slim, high impedance connection, the path of the high
frequency noise can be controlled.
Board Edge
RJ/Mag.
Chassis
GND
RJ Shield
connected
to Chassis
GND
Capacitor
Stuffing
Options
Capacitor
Stuffing
Options
Digital
GND
Resistive
Terminations
LAN IC
C1 C2 C3 C4 C5 C6
Capacitors
Value
C1, C6
4.7
µ
F or 10
µ
F
C2, C3, C4, C5,
470 pF to 0.1
µ
F