Intel EP80579 Guide

Intel
®
EP80579 Integrated Processor Product Line May 2010
Order Number: 320068-005US 138
PCI Express* Interface—Intel
®
EP80579 Integrated Processor Product Line
Follow the specified stackup in Figure TBD to avoid frequency-dependent loss effects
that may occur at PCI Express edge rates. If the dielectric characteristics are different
from those specified in the stackup (TBD), the solution space presented in this section
may not apply. This inaccuracy may happen even if the trace widths are adjusted to
meet the specified impedance targets because the attenuation of high frequency
components is a function of the trace width, thickness, and dielectric characteristics.
Simulate and validate any design that deviates from the specified stackup.
10.1.2 Impedance Requirements
The tables in this section show the required geometry for the stripline and microstrip
PCI Express differential signals.
Stripline traces are routed on inner layers. Signals travel slower on stripline traces than
on microstrip traces. They have a very low FEXT and very low dispersion. Table 48
indicates the differential impedance and trace width used in routing stripline signals.
Microstrip traces are routed on the outer layers. Signals travel a bit faster on the
microstrip traces compared to stripline traces. They have significant FEXT and notable
frequency and mode dependence on velocity. Table 48 indicates the differential
impedance and trace width used in routing microstrip signals.
Table 48. Trace Width/Impedance Requirement for Stripline and Microstrip Layers
Trace Width Nominal Trace Spacing
Nominal Trace Impedance
(Zo)
Stripline Layers (3 or 8)
4.5 mils 5.5 mils edge-to-edge 90 Ω ±10% (Differential)
Microstrip Layers (1 or 10)
4.75 mils 5.25 mils edge-to-edge 90 Ω ±10% (Differential)
Figure 87. Recommended PCI Express Stripline Trace Width/Spacing
Differential
Pair
Distances in Mils
Non-
Interface
Signal
Non-
Interface
Signal
Differential
Pair
18 or 3x dielectric
thickness
18 or 3x
dielectric
thickness
18 or 3x dielectric
thickness
4.5
5.5
4.5 4.5 4.5
5.5

Intel EP80579 Specifications

General

Brand	Intel
Model	EP80579
Category	Computer Hardware
Language	English