General Layout And Routing Guidelines; Trace Attribute Recommendations; Table 2-6. Recommended Trace Width And Spacing - VIA Technologies Apollo Pro133A Design Manual

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2.3 General Layout and Routing Guidelines

This section provides general layout rules and routing guidelines for designing Apollo Pro133A motherboards.

2.3.1 Trace Attribute Recommendations

For most signal traces on an Apollo Pro133A motherboard layout, 5-mil trace width and 10-mil spacing are advised. To reduce
trace inductance, minimum power trace width is set at 30 mils. As a quick reference, recommended trace width and spacing for
different trace types are listed in Table 2-6.
Trace Type
In high-speed bus design, general rules for minimizing crosswalk are listed below:
•
Maximize the distance between traces. Maintain a minimum 10 mils space between traces wherever possible.
•
Avoid parallelism between traces on adjacent layers.
•
Select a board stack-up that minimizes coupling between adjacent traces.
•
The recommended motherboard impedance should be in the range of 65 ohm +/- 5 ohm.
Preliminary Revision 0.5, November 19, 1999

Table 2-6. Recommended Trace Width and Spacing

Trace Width (mils)
Signal
Clock
Power
Design Guide - VT82C694X Apollo Pro133 with VT82C686A
5 or wider
15 or wider
30 or wider
29
Spacing (mils)
10 or wider
15 or wider
20 or wider
Motherboard Design Guidelines