Nvidia Jetson Xavier NX Design Manual page 59

Parameter
Trace impedance: Diff pair
Reference plane
Trace spacing/Length/Skew
Trace loss characteristic:
Trace spacing (pair-pair)
Stripline
Microstrip: pre 1.4b
Microstrip: 1.4b/2.0
Trace spacing (Main link to DDC)
Stripline
Microstrip
Max total length/delay (1.4b/2.0 - up to
5.94Gbps)
Stripline
Microstrip (5x spacing)
Microstrip (7x spacing)
Max Total Length/Delay (Pre-1.4b - (up to
165Mhz)
Microstrip
Max intra-pair (within pair) skew
Max inter-pair (pair to pair) skew
Max GND transition via distance
Via
Topology
Minimum impedance dip
Recommended via dimension
drill/pad
Antipad
via pitch
GND via
Max # of vias
PTH via
u-via
Max via stub length
Topology
The main route via dimensions should comply with the via structure rules (See via
section)
For the connector pin vias, follow the rules for the connector pin vias (See via section)
The traces after main route via should be routed as 100Ω differential or as uncoupled
50ohm SE traces on PCB top or bottom.
Max distance from R to main trace (seg B)
PD
Max distance from AC cap to RPD stubbing
point (seg A)
Max distance between ESD and signal via
Add-on Components
NVIDIA Jetson Xavier NX
Requirement
100
GND
< 0.8
< 0.4
3x
4x
5x to 7x
3x
5x
100 (690)
90 (531)
100 (590)
Stripline 254 (1500)
225 (1500)
0.15 (1)
150
1x
- Y-pattern is recommended
- keep symmetry
97
92
200/400
840
880
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 if total channel loss
meets IL spec.
0.4
1
~0
3
Units Notes
Ω ±10%. Target is 100Ω. 95Ω for the
breakout and main route is an
implementation option.
dB/in. @ 3GHz The max length is derived based on this
dB/in. @ 1.5GHz characteristic. See Note 1.
For Stripline, this is 3x of the thinner of
dielectric above and below.
For Stripline, this is 3x of the thinner of
dielectric above and below.
Propagation delay: 175ps/in. for stripline,
150ps/in. for microstrip). Stripline is
mm (ps) preferred.
Propagation delay: 175ps/in. for stripline,
150ps/in. for microstrip).
mm (ps)
mm (ps) See notes 1, 2, and 3
ps See notes 1, 2, and 3
Diff pair via pitch For signals switching reference layers,
add one or two ground stitching vias. It is
recommended they be symmetrical to
signal vias.
Xtalk suppression is the best by Y-
pattern. Also it can reduce the limit of
pair-pair distance. Need review
Ω@200ps
(NEXT/FEXT check) if via placement is
Ω@35ps
not Y-pattern. See Figure 8-11
uM
GND via is used to maintain return path,
while its Xtalk suppression is limited
mm long via stub requires review (IL and
resonance dip check)
See topology in Figure 8-8
mm
mm
mm
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