Nvidia Jetson Xavier NX Design Manual page 53

Parameter
Trace Length, Spacing and Skew
Trace loss characteristic (max)
Up to HBR2
HBR3
Max PCB via dist. from connector
RBR/HBR
HBR2/HBR3
Max trace length/delay from Jetson Xavier NX
TX to connector (Up to HBR3)
Stripline
Microstrip
Trace spacing (pair-pair)
Stripline
Microstrip (HBR/RBR)
Microstrip (HBR2/HBR3)
Trace spacing (Main link to AUX)
Stripline/Microstrip
Max intra-pair (within pair) skew
Max inter-pair (pair-pair) skew
Via
Max GND transition via distance
Via Structure
Impedance dip (min)
Recommended via dimension Drill/Pad
for impedance control
Antipad (min)
Via pitch (min)
Topology
GND via
Max # of vias
PTH vias
Micro vias
Max via stub length
AC Cap
NVIDIA Jetson Xavier NX
Requirement Units
0.81 dB/in@ 2.7GHz
0.7 dB/in@ 4.0GHz
No requirement mm (in)
7.63 (0.3)
100 (700) mm (ps)
100 (600)
3x dielectric
4x
5x
3x / 5x dielectric
0.15 (1) mm (ps)
150 ps
< 1x diff pair pitch
97 Ω @ 200ps
92 Ω @ 35ps
200/400 um
840 um
880 um
Y-pattern is recommended
Keep symmetry
For in-line via, the distance from a via
of one lane to the adjacent via from
another lane >= 1.2mm center-
center.
Place GND via as symmetrically as
possible to data pair vias. Up to four
signal vias (2 diff pairs) can share a
single GND return via
2 if all vias are PTH via
Not limited as long as total channel
loss meets IL spec
0.4 mm
Notes
The max lengths are derived based on
this characteristic. See Note 2.
175ps/inch assumption for stripline,
150ps/inch for microstrip.
See Note 3
See Note 4
For signals switching reference layers,
add symmetrical GND stitching via near
signal vias.
The via dimension is required for HDMI-
DP co-layout.
Y-pattern helps with Xtalk suppression.
It can also reduce the limit of pair-pair
distance. Need review (NEXT/FEXT
check) if via placement is not Y-pattern.
See eDP/DP guideline Figure 8-5
See eDP/DP guideline Figure 8-6
GND via is used to maintain a return
path, while its Xtalk suppression is
limited.
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