PCM-072/phyCORE-AM64xx System on Module
L-860e.A0
© PHYTEC America L.L.C. 2022
33
Figure 13. Fan design reference circuit
4.11 Layout Guidelines
4.11.1 High-Speed Differential Signal Routing Guidelines
Spacing
•
Implement proper trace width and spacing to yield the recommended differential impedance value.
•
Spacing between the differential pairs and other traces should be at least twice the distance between the inter-
pair spacing.
•
Avoid routing high-speed signals near other sensitive circuits (such as crystals, oscillators, switching regulators,
clock signals, etc.).
Routing
•
Route the two traces of a differential pair on the same layer(s).
•
Route signals over an adjacent, solid ground reference plane. Ensure there are no layers between the routing layer
and reference layer.
•
Avoid routing across a gap or cut-out in the reference plane or across different reference planes. Cuts in the
reference plane should be avoided in general.
•
Avoid sharp bends on differential lanes.
•
Minimize total trace length.
•
Keep the length of the two traces in a differential pair as close as possible. Recommended length matching is listed
in the various Design In Guide sub-sections contain in this document as well as the length of the traces on the
SOM. This information can be used to further correct or avoid worsening any SOM trace length mismatches in
your own design.
