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4.1.3. USB Interface Design Considerations
Table 12: USB Interface Trace Length Inside the Module (Unit: mm)
Pin Name
USB0_DP
USB0_DM
USB0_SS_TX_P
USB0_SS_TX_M
USB0_SS_RX_P
USB0_SS_RX_M
USB1_DP
USB1_DM
USB1_SS_TX_P
USB1_SS_TX_M
USB1_SS_RX_P
USB1_SS_RX_M
USB2_DP
USB2_DM
USB3_DP
USB3_DM
To ensure performance, you should follow the following principles when designing USB interfaces:
Route USB signal traces as differential pairs with surrounded ground. The impedance of USB
⚫
differential trace is 90 Ω.
⚫
Route USB differential traces at the inner-layer of the PCB, and surround the traces with ground on
that layer and ground planes above and below. For signal traces, provide clearance from power
supply traces, crystal-oscillators, magnetic devices, sensitive signals like RF signals, analog signals,
and noise signals generated by clock, DC-DC, etc.
⚫
The reference ground plane under the USB signal traces must be continuous without any cuts or vias
SG368Z_Series_Hardware_Design
Pin No.
Length
112
31.89
113
31.80
107
34.35
108
34.38
109
31.63
110
31.55
79
21.90
83
21.81
84
22.27
88
22.45
89
26.00
92
26.12
289
43.18
292
43.00
295
42.56
297
42.31
Smart Module Series
Length Matching (P-M)
0.09
-0.03
0.08
0.09
-0.18
-0.12
0.18
0.25
44 / 113
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