65
PCI-X Layout Guidelines
6.4.19
PCI 33 MHz Mixed Topology
and
provides routing details for a topology with for an embedded PCI 33 MHz
design with slots.
Group Spacing
Spacing from other groups: 25 mils minimum edge-to-edge
Trace Length 1 TL1: From
80331 signal Ball to first
junction
4.5” maximum
Trace Length TL2 to TL4
between junctions
1.5” minimum - 3.0” maximum
Trace Length TL_EM1 to
TL_EM8 junction to
embedded devices
2.0” minimum - 3.0” 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
Table 25.
PCI 33 MHz Embedded Routing Recommendations (Sheet 2 of 2)
Figure 34.
PCI 33 MHz Mixed Mode Routing Topology
Table 26.
PCI 33 MHz Mixed Mode Routing Recommendations (Sheet 1 of 2)
Parameter
Routing Guideline for lower AD
Bus
Routing Guideline for
upper AD Bus
Reference Plane
Route over an unbroken ground plane
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)
57 Ohms +/- 15%
Stripline Trace Spacing
10 mils, from edge to edge
Microstrip Trace Spacing
15 mils, from edge to edge
Group Spacing
Spacing from other groups: 25 mils minimum edge-to-edge
TL
_A
D
1
TL3
CONN2
T
L_A
D
2
AD2
TL4
CONN3
T
L_A
D
3
AD3
TL5
CONN4
T
L_A
D
4
AD4
TL1
T
L_E
M1
EM1
TL_
E
M
2
EM2
CONN1
AD1
Summary of Contents for 80331
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