FSB Design Guidelines
R
Intel
®
855PM Chipset Platform Design Guide
71
Figure 35. Processor COMP[2] and COMP[0] 18-Mil Wide Dog Bones and Traces
PRIMARY SIDE
PRIMARY SIDE
SECONDARY SIDE
SECONDARY SIDE
COMP0
COMP2
18-mil Dog Bone
18-mil Trace
27.4
Ω
1%
27.4
Ω
1%
COMP1
COMP3
PRIMARY SIDE
PRIMARY SIDE
SECONDARY SIDE
SECONDARY SIDE
COMP0
COMP2
18-mil Dog Bone
18-mil Trace
27.4
Ω
1%
27.4
Ω
1%
COMP1
COMP3
4.1.8.2.
Intel 855PM MCH AGTL+ I/O Buffer Compensation
The Intel 855PM MCH AGTL+ I/O buffer resistive compensation signals pins of the MCH,
HRCOMP[1:0], should each be pulled-down to ground with a 27.4
± 1% resistor. The maximum trace
length from pin to resistor should be less than 0.5 inches long and includes the dog bone connection on
the primary side from the BGA land to the dog bone via. This < 0.5 inch long connection should be 18
mils wide to achieve the Zo = 27.4
target. Also, the routing for HRCOMP should be at least 25 mils
away from any switching signal. Figure 36 illustrates the recommended layout for the Intel 855PM
MCH HRCOMP[1:0] resistors that are placed on the motherboard’s secondary side to save space as well
as to make the shortest possible connection without interacting with FSB routing. To avoid GND via
interaction of the HRCOMP[1:0] resistors, each should share the ground pin vias of the MCH’s AE1
and AD12 ground pins to make the ground connection.
Содержание 855PM
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Страница 32: ...General Design Considerations R 32 Intel 855PM Chipset Platform Design Guide This page intentionally left blank...
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Страница 182: ...Hub Interface R 182 Intel 855PM Chipset Platform Design Guide This page intentionally left blank...
Страница 228: ...I O Subsystem R 228 Intel 855PM Chipset Platform Design Guide This page intentionally left blank...
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