Nvidia Jetson TX2 Manual page 47

Parameter
Trace spacing (Pair-Pair)
Stripline
Microstrip: pre 1.4b
Microstrip: 1.4b/2.0
Trace spacing Stripline
(Main Link to DDC) Microstrip
Max Total Delay (1.4b/2.0 - up to
5.94Gbps)
Stripline
Microstrip (5x spacing)
Microstrip (7x spacing)
Max Total Delay (Pre-1.4b)
(up to 165Mhz) Microstrip
Stripline
Max Intra-Pair (within pair) Skew
Max Inter-Pair (pair to pair) Skew
Max GND transition Via distance
Via
Topology
Minimum Impedance Dip
Recommende d Via Dime nsion
drill/pad
Antipad
Via pitch
GND via
Connector pin via
Max # of Vias PTH via
Max Via Stub Length
Serpentine
Min bend angle
JETSON TX2/TX2i OEM PRODUCT | DESIGN GUIDE | 20180618
Requirement
3x
4x
5x to 7x
3x
5x
63.5/2.5 (437)
50.8/2.0 (300)
63.5/2.5 (375)
254/10 (1500)
225/8.5 (1500)
0.15 (1)
150
1x
8. Y-pattern is recommended
9. keep symmetry
97
92
200/400
840
880
Place GND via as symmetrically as possible to data pair
vias. Up to 4 signal vias (2 diff pairs) can share a single
GND return via
-
The break-in trace to the connector pin via should
be routed on the BOTTOM in order to av oid v ia stub
ef f ect
-
Equal spacing (0.8mm) between adjacent signal
v ias.
-
The x-axis distance between signal and GND via
should be > 0.6mm
4 if all vias are PTH via
u-via Not limited as long as total channel loss meets IL spec.
No breakout: ≤ 3 vias
0.4
135
NVIDIA Jetson TX2/TX2i OEM Product Design Guide
Units Notes
For Stripline, this is 3x of the thinner of above and
dielectric below.
dielectric For Stripline, this is 3x of the thinner of above and
below.
Propagation delay: 175ps/in. for stripline, 150ps/in. for
microstrip).
mm/in (ps)
mm/in (ps) Propagation delay: 175ps/in. for stripline, 150ps/in. for
microstrip).
Mm (ps) See Notes 2, 3 & 4
ps See Notes 2, 3 & 4
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
Ω@200ps
pair-pair distance. Need
Ω@35ps
review (NEXT/FEXT check)
if via placement is not Y-
uM
pattern.
GND via is used to maintain return path, while its Xtalk
suppression is limited
breakout on the same layer as main trunk: ≤ 4 vias
mm long via stub requires review (IL & resonance dip check)
deg (a)
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