Design Principles For Usb Interfaces - Quectel SG560D Series Hardware Design

4.1.3. Design Principles for USB Interfaces

Table 14: USB Trace Length Inside the Module
Pin No. Signal
354 USB0_DP
358 USB0_DM
360 USB0_SS1_TX_P
357 USB0_SS1_TX_M
356 USB0_SS1_RX_P
353 USB0_SS1_RX_M
348 USB0_SS2_TX_P
345 USB0_SS2_TX_M
352 USB0_SS2_RX_P
349 USB0_SS2_RX_M
622 USB1_DP
621 USB1_DM
620 USB0_DP_AUX_P
619 USB0_DP_AUX_M
To ensure USB performance, follow the following principles while designing the USB interface.
⚫
It is important to route the USB signal traces as differential pairs with total grounding. The impedance
of USB differential trace is 90 Ω.
⚫
The ground reference plane under the USB signals must be continuous without any cuts or any holes
to ensure impedance continuity.
⚫
Pay attention to the influence of junction capacitance of ESD protection components on USB data
lines. Typically, the capacitance value should be less than 2 pF for USB 2.0 and less than 0.5 pF for
USB 3.1. Keep the ESD protection components as close as possible to the USB connector.
⚫
Do not route USB signal traces under crystals, oscillators, magnetic devices, audio signal, and RF
signal traces. Route USB differential traces in inner-layer with ground shielding on not only upper and
lower layers but also right and left sides.
⚫
Do not route USB 3.1 signal traces under RF signal traces. Crossing or paralleling with RF signal
SG560D_Series_Hardware_Design
Length (mm)
35.95
35.48
26.51
26.65
24.03
24.13
26.16
26.30
26.79
26.67
22.95
22.54
21.41
21.22
Smart Module Series
Length Difference (P - M)
0.47
-0.14
-0.10
-0.14
0.12
0.41
0.19
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