Nvidia JETSON TX2 - Page 47

NVIDIA Jetson TX2/TX2i OEM Product Design Guide
JETSON TX2/TX2i OEM PRODUCT | DESIGN GUIDE | 20180618 47
Parameter
Requirement
Units
Notes
Trace spacing (Pair-Pair)
Stripline
Microstrip: pre 1.4b
Microstrip: 1.4b/2.0
3x
4x
5x to 7x
dielectric
For Stripline, this is 3x of the thinner of above and
below.
Trace spacing Stripline
(Main Link to DDC) Microstrip
3x
5x
dielectric
For Stripline, this is 3x of the thinner of above and
below.
Max Total Delay (1.4b/2.0 - up to
5.94Gbps)
Stripline
Microstrip (5x spacing)
Microstrip (7x spacing)
63.5/2.5 (437)
50.8/2.0 (300)
63.5/2.5 (375)
mm/in (ps)
Propagation delay: 175ps/in. for stripline, 150ps/in. for
microstrip).
Max Total Delay (Pre-1.4b)
(up to 165Mhz) Microstrip
Stripline
254/10 (1500)
225/8.5 (1500)
mm/in (ps)
Propagation delay: 175ps/in. for stripline, 150ps/in. for
microstrip).
Max Intra-Pair (within pair) Skew
0.15 (1)
Mm (ps)
See Notes 2, 3 & 4
Max Inter-Pair (pair to pair) Skew
150
ps
See Notes 2, 3 & 4
Max GND transition Via distance
1x
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.
Via
Topology
8. Y-pattern is recommended
9. keep symmetry
Xtalk suppression is the
best by Y-pattern. Also it
can reduce the limit of
pair-pair distance. Need
review (NEXT/FEXT check)
if via placement is not Y-
pattern.
Minimum Impedance Dip
97
92
@200ps
@35ps
Recommended Via Dimension
drill/pad
Antipad
Via pitch
200/400
840
880
uM
GND via
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
GND via is used to maintain return path, while its Xtalk
suppression is limited
Connector pin via
- The break-in trace to the connector pin via should
be routed on the BOTTOM in order to av oid via stub
effect
- Equal spacing (0.8mm) between adjacent signal
vias.
- The x-axis distance between signal and GND via
should be > 0.6mm
Max # of Vias PTH via
u-via
4 if all vias are PTH via
Not limited as long as total channel loss meets IL spec.
No breakout:  3 vias
breakout on the same layer as main trunk:  4 vias
Max Via Stub Length
0.4
mm
long via stub requires review (IL & resonance dip check)
Serpentine
Min bend angle
135
deg (a)