Intel 820E Personal Computer User Manual


 
Intel
®
820E Chipset
R
Design Guide 121
Figure 77. Dual-Footprint Analog Interface
IO_subsys_dual_footprint_analog_
IF
Magnetics
module
TDP
RJ45
Intel
®
82562EH/82562ET
TDN
RDP
RDN
RJ11
TXP
TXN
Tip
Ring
Intel
82562EH
config.
Intel
82562ET
config.
Additional guidelines for this configuration are as follows:
L = 0.5 inch to 6.5 inches
Stub = <0.5 inch
Either the Intel 82562EH or Intel 82562ET/82562EM component can be installed. Not both.
Pins 28, 29, and 30 of the Intel 82562ET component overlap pins 17, 18, and 19 of the Intel
82562EH component.
Overlapping pins are tied to ground.
No other signal pads should overlap or touch.
Signal lines LAN_CLK, LAN_RSTSYNC, LAN_RXD[0], LAN_TXD[0], RDP, RDN, RXP/Ring,
and RXN/Tip are shared by the Intel
82562EH and Intel 82562ET component configurations.
No stubs should be present when the Intel 82562ET component is installed.
The packages used for the dual footprint are the TQFP for the Intel 82562EH component and the
SSOP for the Intel
82562ET component.
A 22 resistor can be placed at the driving side of the signal line to improve signal quality on the
LAN connect interface.
Resistors should be placed as close as possible to components.
Use components that can satisfy both the Intel 82562ET and Intel 82562EH component
configurations (i.e., a magnetics module).
Install components for either the Intel 82562ET or Intel 82562EH component configuration. Only
one configuration can be installed at a time.
Route shared signal lines such that stubs are not present or are minimized.
Stubs may occur on shared signal lines (i.e., RDP and RDN). These stubs result from traces routed
to an uninstalled component.
Use 0 resistors to connect and disconnect circuitry not shared by both configurations. Place
resistor pads along the signal line to reduce stub lengths.
Refer to the Intel 820E CRB layout for routing examples.