50
PCI-X Layout Guidelines
6.4.4
Embedded PCI-X 133 MHz Alternate Topology
This section lists another embedded topology with routing recommendations for PCI-X 133 MHz.
shows the block diagram of this topology and
recommendations.
Figure 19.
Embedded PCI-X 133 MHz Alternate Topology
Table 11.
Embedded PCI-X 133 MHz Alternate Topology Routing Recommendations
Parameter
Routing Guideline for Lower AD Bus
Reference Plane
Preferred Layer
Route over an unbroken ground plane
Stripline
Break out
5 mils on 5 mils spacing. Maximum length of breakout region is 500 mils
Motherboard impedance
(both Microstrip and stripline)
50 ohms +/- 15%
Add-in card impedance (both
Microstrip and stripline)
60 ohms +/- 15%
Stripline Trace Spacing
12 mils edge to edge
Microstrip Trace Spacing
18 mils, edge to edge
Group Spacing
Spacing from other groups: 25 mils minimum edge to edge
Trace Length 1 (TL1): From
80331 signal Ball to first
device
1.5” minimum - 3.5” maximum
Trace Length 3 TL2: First
device to second device.
1.5” minimum - 3.5” maximum
Length Matching
Requirements:
No length matching is required among datalines. For length matching for clocks,
refer clock guidelines
Number of vias
Three vias for each path
TL1
EM1
EM2
TL2
Summary of Contents for 80331
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