Intel Pentium 4 Design Manual page 182

I/O Controller Hub 2
The following are additional guidelines for this configuration:
• L = 3 .5 to 4.5 inches
• Stub < 0.5 inches
• Either 82562EH or 82562ET/82562EM can be installed. Not both
• 82562ET pins 28,29, and 30 overlap with 82562EH pins 17,18, and 19.
• Overlapping pins are tied to ground.
• No other signal pads should overlap or touch.
• The 82562EH and 82562ET configurations share signal lines LAN_CLK, LAN_RSTSYNC,
LAN_RXD[0], LAN_TXD[0], RDP, RDN, RXP/Ring, and RXN/Tip.
• No stubs should be present when 82562ET is installed.
• Packages used for the Dual Footprint are TQFP for 82562EH and SSOP for 82562ET.
• A 22Ω resistor can be placed at the driving side of the signal line to improve signal quality on
the LAN connect interface.
• Resistor should be placed as close as possible to the component.
• Use components that can satisfy both the 82562ET and 82562EH configurations
(i.e., magnetics module).
• Install components for either the 82562ET or the 82562EH configuration. Only one
configuration can be installed at a time.
• Route shared signal lines such that stubs are not present or are kept to a minimum.
• Stubs may occur on shared signal lines (i.e., RDP and RDN). These stubs are due to traces
routed to an uninstalled component. In an optimal layout, there should be no stubs.
• Use 0 Ω resistors to connect and disconnect circuitry not shared by both configurations. Place
resistor pads along the signal line to reduce stub lengths.
• Traces from magnetics to connector must be shared and not stubbed. An RJ-11 connector that
fits into the RJ-45 slot is available. Any amount of stubbing will destroy both HomePNA* and
Ethernet performance.
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Intel Pentium 4 Processor / Intel
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850 Chipset Family Platform Design Guide
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