Nvidia Jetson Orin Nano Series - Page 43

USB and PCIe
PRELIMINARY INFORMATION
Jetson Orin NX Series and Jetson Orin Nano Series DG-10931-001_v1.1 | 32
Parameter
Requirement
Units
Notes
Near End Crosstalk (NEXT)
dB
DC 5GHz per each TX-RX NEXT
Impedance
Trace Impedance: Diff pair / Single Ended
85 / 43
±15%. Intrinsic Zdf, does not account
for coupling from other trace pairs
Reference plane
GND
Trace Length/Skew
Trace loss characteristic:
Gen1
Gen2
< 0.6
< 1
dB/in @ 2.5
GHz
dB/in @ 5G Hz
Based on the dielectric material
EM370(Z). The following max length is
derived based on this characteristic.
The length constraint must be re-
defined if the loss characteristic is
changed.
Note that microstrip loss could be
similar to stripline due to humidity
effect.
Breakout Region Max length
11
mm
Minimum trace width and spacing
Max Trace Length (delay)
Gen1 Host
Gen1 Device
Gen2 Host or Device
160 (1071)
107 (714)
114 (765)
mm (ps)
Stripline (6.7ps/mm) assumed.
CMC use length reduction = 30 mm
(Gen1/2).
ESD use length reduction = 10 mm
(Gen1), 12.5 mm (Gen2).
Max Intra-Pair Skew (RX/TX_N to RX/TX_P)
0.15 (1)
mm (ps)
Do not perform length matching within
breakout region. Trace length matching
should be done before discontinuities.
Differential pair uncoupled length
6.29 (41.9)
mm (ps)
Trace Spacing for TX/RX Interleaving
Trace Spacing: Microstrip / Stripline
Pair-Pair
To Ref plane and SMT pad
To unrelated high-speed signals
4x / 3x
4x / 3x
4x / 3x
Dielectric
height
Trace Spacing for TX/RX Non-interleaving
TX-RX Xtalk is very critical in PCB trace routing. The ideal solution is to route TX and RX on different layers.
If routing on the same layer, strongly recommend not interleaving TX and RX lanes
If have to have interleaving routing in breakout, all the inter-pair spacing should follow the rule of inter-SNEXT (between TX/RX pair
spacing)
The breakout trace width is suggested to be the minimum to increase inter-pair spacing
Do not perform serpentine routing for intra-pair skew compensation in the breakout region
Min Inter-SNEXT (between TX/RX)
Breakout
Main-route
4.85x
3x
Dielectric
height
This is the recommended dimensions
for meeting the NEXT requirement.
Stripline structure in a GSSG structure
is assumed (holds in broadside-coupled
stripline structure)
Max length
Breakout
Main-route
11
Max trace length -
LBRK
mm
Via
Topology
Y-pattern is recommended
Keep symmetry
Y-pattern helps with Xtalk suppression.
It can also reduce the limit of the pair-
pair distance. Review needed
(NEXT/FEXT check) if via placement
does not use Y-pattern.
GND via
Place GND via as symmetrically as
possible to data pair vias. Up to 4
GND via is used to maintain return
path, while its Xtalk suppression is
limited