Specifications

Intel
®
810E2 Chipset Platform
R
Design Guide 93
3.21.4.2. Crystals and Oscillators
To minimize the effects of EMI, clock sources should not be placed near I/O ports or board edges.
Radiation from these devices may be coupled onto the I/O ports or out of the system chassis. Crystals
should also be kept away from the Ethernet magnetics module to prevent interference with
communication. If they exist, the retaining straps of the crystal should be grounded to prevent possible
radiation from the crystal case. Also, the crystal should lie flat against the PC board to provide better
coupling of the electromagnetic fields to the board.
For noise-free and stable operation, place the crystal and associated discrete components as close as
possible to the 82562ET or 82562EM. Keep the trace length as short as possible and do not route any
noisy signals in this area.
3.21.4.3. Intel
®
82562ET / 82562EM Termination Resistors
The 100-Ω (1%) resistor used to terminate the differential transmit pairs (TDP/TDN) and the 120-Ω
(1%) receive differential pairs (RDP/RDN) should be placed as close as possible to the LAN connect
component (82562ET or 82562EM). This is due to the fact that these resistors terminate the entire
impedance seen at the termination source (i.e., 82562ET), including the wire impedance reflected
through the transformer.
Figure 53. Intel
®
82562ET/82562EM Termination
xxET-xxEM_Term
82562ET
Magnetics
Module
RJ45
Place termination resistors as
close to 82562ET as possible.
LAN Connet
Interface