49
PCI-X Layout Guidelines
6.4.3
Embedded PCI-X 133 MHz
This section lists the routing recommendations for PCI-X 133 MHz without a slot.
shows
the block diagram of this topology and
describes the routing recommendations.
Figure 18.
Embedded PCI-X 133 MHz Topology
Table 10.
Embedded PCI-X 133 MHz 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 junction
1.75” minimum - 4.0” maximum
Trace Length 2 junction of TL_EM1
and TL_EM2 to embedded device
1.25” minimum - 3.25” 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
T
L_E
M
1
EM1
TL
_
E
M
2
EM2
Summary of Contents for 80331
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