Usb Interface - Quectel EC25-AUX Hardware Design

3.10. USB Interface

EC25 contains one integrated Universal Serial Bus (USB) interface which complies with the USB 2.0
specification and supports high-speed (480Mbps) and full-speed (12Mbps) modes. The USB interface
can only serves as a slave device and is used for AT command communication, data transmission, GNSS
NMEA sentences output, software debugging, firmware upgrade and voice over USB. The following table
shows the pin definition of USB interface.
Table 10: Pin Description of USB Interface
Pin Name Pin No.
USB_DP 69
USB_DM 70
USB_VBUS 71
GND 72
For more details about the USB 2.0 specifications, please visit http://www.usb.org/home.
The USB interface is recommended to be reserved for firmware upgrade in customers' designs. The
following figure shows a reference circuit of USB interface.
EC25_Hardware_Design
I/O Description
IO USB differential data bus (+)
IO USB differential data bus (-)
USB power supply,
PI
used for USB detection
Ground
Figure 19: Reference Circuit of USB Application
LTE Standard Module Series
EC25 Hardware Design
Comment
Require differential
impedance of 90Ω
Require differential
impedance of 90Ω
Typical 5.0V
50 / 130