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PCM-072/phyCORE-AM64xx System on Module
L-860e.A0
© PHYTEC America L.L.C. 2022
71
Table 37 USB0 Connections at the phyCORE-Connector
X1 Pin #(s)
SOM Signal(s)
Type Level
Description
A34
X_USB0_VBUS
A/I
5V
USB Level-shifted VBUS Input
A32
X_USB0_ID
A/I
3.3V
USB 2.0 Dual-Role Device Role Select
A33
X_USB0_DRVVBUS
O
3.3V
USB VBUS control output (active high)
A18
X_USB0_DM
I/O
Differential
USB OTG1 2.0 Differential Data Negative
A19
X_USB0_DP
I/O
Differential
USB OTG1 2.0 Differential Data Positive
7.8.2 USB Design In Considerations
•
X_USB0_DP/X_USB0_DM trace lengths should be matched and should be no more than 12 inches in total length
(SOM + Carrier Board), though 4 inches is considered typical. The table below shows the length of the USB2.0
traces on the SOM and required constraints.
Table 38 phyCORE-AM64xx USB0 Layout Characteristics
Signal Name
Length (µm)
Length
Matching
(µm)
Single Ended
Impedance (Ω)
Differential
Impedance (Ω)
SOM
Trace
Max Total
Max CB
Trace
X_USB0_DP
3300
304800
301500
1270
50
100
X_USB0_DM
3326
304800
301474
50
7.8.2.1
USB3.1 (SERDES) Design In Considerations
•
The USB3.0 subsystem allows for up to 1x USB SuperSpeed port.
•
Minimize the distance between AC capacitors (TX only) and common mode filters (CMF).
•
Minimize the distance between common mode filters (CMF) and ESD protection devices.
•
Minimize the distance between ESD protection devices and USB connectors.
•
Ensure there are no cuts in the ground plane within the USB3.0 routing region, with the exception of cut-outs in
the ground reference layer directly underneath the AC capacitors, ESD devices, and common mode filters to
minimize additional capacitance. An example of this in layout is shown in
The right image shows a
filter, and the left image shows the ground plane cutout beneath it.
Figure 25. Layout example of a ground cutout.