51
PCI-X Layout Guidelines
6.4.5
Combination of PCI-X 133 MHz Slot and Embedded Topology
and
combine the two topologies using both a slot and an embedded device.
Figure 20.
Embedded PCI-X 133 MHz Topology
Table 12.
Embedded and Slot PCI-X 133 MHz Routing Recommendations
Parameter
Routing Guideline for Lower AD Bus Routing Guideline for Upper 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)
57 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 min, center to center
Trace Length 1 (TL1): From
80331 signal ball to first
junction
1.25” minimum - 3.0” maximum
1.25” minimum - 3.0” maximum
Trace Length 3 TL_EM1
from the first junction to the
embedded device
1.25” minimum - 3.75” maximum
1.25” minimum - 3.75” maximum
Trace Length TL_AD1 - from
connector to the receiver
0.75” - 1.5” maximum
1.75” - 2.75” maximum
Length Matching
Requirements:
No length matching is required among datalines. For length matching for clocks,
refer clock guidelines
.
Number of vias
Three vias max
TL1
CONN1
AD1
EM1
T
L_E
M1
TL
_A
D
1
Summary of Contents for 80331
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