Intel 82562EX, Руководство по конструкции

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82540EP/82541(PI/GI/EI) & 82562EZ(EX) Dual Footprint Design Guide
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Figure 10. 82562EZ(EX) PLC Device Differential Signal Termination
4.2.2 Light Emitting Diodes for Designs Based on 82562EZ(EX) PLC
The 82562EZ(EX) PLC device has three high-current outputs to directly drive LEDs for link,
activity and speed indication. Since LEDs are likely to be integral to a magnetics module, take care
to route the LED traces away from potential sources of EMI noise. In some cases, it may be
desirable to attach filter capacitors.
4.3 Layout for the 82541xx Gigabit Ethernet Controller
4.3.1 Termination Resistors for Designs Based on 82541xx
The four differential pairs are terminated with 49.9
Ω
(1% tolerance) resistors, placed near the
82541xx controller. One resistor connects to the MDI+ (MDI positive) signal trace and another
resistor connects to the MDI- (MDI negative) signal trace. The opposite ends of the resistors, using
a wide trace, connect together and to ground through a single 0.1
µ
F capacitor. The capacitor
should be placed as close as possible to the 49.9
Ω
resistors using a wide trace.
Do not vary the suggested component values. Be sure to lay out symmetrical pads and traces for
these components such that the length and symmetry of the differential pairs are not disturbed.
4.3.2 Light Emitting Diodes for Designs Based on 82541xx
The 82541xx controller provides four programmable high-current outputs to directly drive LEDs
for link activity and speed indication. Since the LEDs are likely to be integral to a magnetics
module, route the LED traces away from potential sources of EMI noise. In some cases, it may be
desirable to attach filter capacitors.
4.4 Physical Layer Conformance Testing
Physical layer conformance testing (also known as IEEE testing) is a fundamental capability for all
companies with Ethernet LAN products. PHY testing is the final determination that a layout has
been performed successfully. If your company does not have the resources and equipment to
perform these tests, consider contracting the tests to an outside facility.
Intel
LAN
Device
Magnetics
Module
RJ45
LAN Connect
Interface
ICH5
Place termination resistors as close to the Intel LAN device as possible.