Agp 2.0 Routing Summary - Intel VC820 - Desktop Board Motherboard Design Manual

This pair should be separated from the rest of the AGP signals (and all other signals) by at least
20 mils (1:4). The strobe pair must be length matched to less than ±0.1" (i.e., a strobe and its
compliment must be the same length within 0.1").
All AGP Interfaces
The 2X/4X Timing Domain Signals can be routed with 5 mil spacing when breaking out of the
MCH. The routing must widen to the documented requirements within 0.3" of the MCH package.
When matching trace length for the AGP 4X interface, all traces should be matched from the ball
of the MCH to the pin on the AGP connector. It is not necessary to compensate for the length of the
AGP signals on the MCH package.
Reduce line length mismatch to insure added margin. In order to reduce trace to trace coupling
(cross talk), separate the traces as much as possible. All signals in a signal group should be routed
on the same layer. The trace length and trace spacing requirements must not be violated by any
signal. Trace length mismatch for all signals within a signal group should be as close to zero as
possible to provide timing margin.
2.7.4

AGP 2.0 Routing Summary

Table 2-8. AGP 2.0 Routing Summary
Signal
1X Timing Domain
2X/4X Timing
Domain Set#1
2X/4X Timing
Domain Set#2
2X/4X Timing
Domain Set#3
2X/4X Timing
Domain Set#1
2X/4X Timing
Domain Set#2
2X/4X Timing
Domain Set#3
NOTES:
1. Each strobe pair must be separated from other signals by at least 20 mils
2. These guidelines apply to board stackups with 10% impedance tolerance
®
Intel 820 Chipset Design Guide
1,2
Maximum Trace Spacing
Length (5 mil traces)
7.5" 5 mils
7.25" 20 mils
7.25" 20 mils
7.25" 20 mils
1
6" 15 mils
1
6" 15 mils
1
6" 15 mils
Layout/Routing Guidelines
Length
Relative To
Mismatch
No
N/A
Requirement
AD_STB0 and
±0.125"
AD_STB0#
AD_STB1 and
±0.125"
AD_STB1#
SB_STB and
±0.125"
SB_STB#
AD_STB0 and
±0.5"
AD_STB0#
AD_STB1 and
±0.5"
AD_STB1#
SB_STB and
±0.5"
SB_STB#
Notes
None
AD_STB0, AD_STB0#
must be the same
length
AD_STB1, AD_STB1#
must be the same
length
SB_STB, SB_STB#
must be the same
length
AD_STB0, AD_STB0#
must be the same
length
AD_STB1, AD_STB1#
must be the same
length
SB_STB, SB_STB#
must be the same
length
2-35