54
PCI-X Layout Guidelines
6.4.8
PCI-X 100 MHz Embedded Topology
and
combine both a slot and an embedded device.
Figure 23.
Embedded PCI-X 100 MHz Routing Topology
Table 15.
PCI-X 100 MHz Embedded Routing Recommendations
Parameter
Routing Guideline for Lower AD Bus
Reference Plane
Preferred Layer
Route over an unbroken ground plane
Stripline
Breakout
5 mils on 5 mils spacing. Maximum length of the breakout is 500 mils.
Motherboard Trace
Impedance (microstrip and
stripline)
50 Ohms +/- 15%
Add-in card Impedance
(microstrip and stripline)
60 Ohms +/- 15%
Stripline Trace Spacing
12 mils, from edge to edge
Microstrip Trace Spacing
18 mils, from edge to edge
Group Spacing
Spacing from other groups: 25 mils minimum edge to edger
Trace Length 1 TL1: From
80331 signal Ball to first
junction
0.5” minimum - 3.0” maximum
Trace Length TL_EM1 -
between junction and
embedded device
2.5” - 3.5” maximum
Trace Length TL_EM2,
TL_EM3- from second
junction to embedded
devices
1.5” minimum to 3.5 maximum
Length Matching
Requirements:
No length matching is required among datalines. For length matching for clocks,
refer clock guidelines
.
Number of vias
Four vias maximum for each path
TL1
TL_EM2
EM2
TL_EM1
EM1
TL_EM3
EM3
Summary of Contents for 80331
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