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®
Intel
855GME Chipset and Intel
Layout Checklist
13.3.3
IDE Interface Layout Checklist
Table 152.
IDE Interface Layout Checklist
#
1
Traces need to be routed 5 mils wide and 7 mils spaces
2
Max trace length is eight inches long.
3
The two strobe signals must be matched within 100 mils of each
other. The data lines must be within ± 500 mils of the average
length of the two strobe signals.
4
If series resistors are used, they should be placed close to the IDE
connector.
13.3.4
USB 2.0 Layout Checklist
Table 153.
USB 2.0 Layout Checklist (Sheet 1 of 2)
#
With minimum trace lengths, route high-speed clock and USB
1
differential pairs first.
2
Route USB signals ground referenced.
Route USB signals using a minimum of vias and corners. This
3
reduces signal reflections and impedance changes.
When it becomes necessary to turn 90°, use two 45° turns or an
4
arc instead of making a single 90° turn. This reduces reflections
on the signal by minimizing impedance discontinuities.
Do not route USB traces under crystals, oscillators, clock
5
synthesizers, magnetic devices or ICs that use and/or duplicate
clocks.
Stubs on USB signals should be avoided, as stubs will cause
signal reflections and affect signal quality. When a stub is
6
unavoidable in the design, the sum of all stubs on a given data
line should not be greater than 200 mils.
Route all traces over continuous planes (GND) with no
interruptions. Avoid crossing over anti-etch when possible.
Crossing over anti-etch (plane splits) increases inductance and
7
radiation levels by forcing a greater loop area. Likewise, avoid
changing layers with high-speed traces. (Applies to USB signals,
high-speed clocks, as well as slower signals that might be
coupling to them.)
Keep USB signals clear of the core logic set. High current
8
transients are produced during internal state transitions, which
may be difficult to filter out.
Keep traces at least 90 mils away from the edge of the plane (V
or GND depending on which plane to which the trace is routed).
9
This helps prevent the coupling of the signal onto adjacent wires
and helps prevent free radiation of the signal from the edge of the
PCB.
Maintain parallelism between USB differential signals with the
10
trace spacing needed to achieve the target differential impedance.
314
®
6300ESB ICH Embedded Platform Design Guide
Layout Recommendations
Layout Recommendations
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