Usb Interface - Quectel UC20 Hardware Design

3.12. USB Interface

UC20 contains one integrated Universal Serial Bus (USB) transceiver which complies with the USB 2.0
specification and supports high speed (480 Mbps), full speed (12 Mbps) and low speed (1.5 Mbps) mode.
The USB interface is primarily used for AT command, data transmission, GNSS NMEA sentences output,
software debug and firmware upgrade. The following table shows the pin definition of USB interface.
Table 13: USB Pin Description
Pin Name
USB_DP
USB_DM
USB_VBUS
GND
More details about the USB 2.0 specifications, please visit http://www.usb.org/home.
The following figure shows the reference circuit of USB interface.
USB_VBUS
USB_DM
USB_DP
Module
In order to ensure the USB interface design corresponding with the USB 2.0 specification, please comply
with the following principles.
UC20_Hardware_Design
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Pin No. I/O
69 IO
70 IO
71 PI
72
Differential layout
GND
Figure 24: Reference Circuit of USB Application
Description
USB differential data bus (positive).
USB differential data bus (minus).
Used for detecting the USB interface
connected.
Ground.
Close to USB connector
NM_2pF
ESD Array
Confidential / Released
UMTS/HSPA Module Series
UC20 Hardware Design
Comment
Require differential
impedance of 90Ω.
Require differential
impedance of 90Ω.
3.0~5.25V.
Typical 5.0V.
USB_VBUS
USB_DM
USB_DP
GND
USB connector
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