I am currently designing the next iteration of our autonomous robot board that will then carry an Orin NX. While re-checking all controlled trace impedances I realized that the Product Design Guide v1.3 actually specifies a 85R differential impedance for USB 3.2 while all other sources I read so far ask for 90R. Might this be a typo or is there a reasoning behind this non-standard impedance? I do know that the impedances are ±15%, but just want to keep the traces as optimal as possible in our design as there are some points that we have no access to that might deteriorate the signal quality.
Thanks! But is the impedance on the Orin NX then 85R? After all each impedance change will lead to reflections in some extent so I try to minimize these.
Hitting the impedance exactly right is either rather difficult or expensive.
The impedance depends on the amount of resin in the prepreg, the thickness of the pressed layer and even on the orientation of the trace with respect to the fabric. Fabrication tolerances of +/- 10% are pretty normal and in most cases no problem.