LTE Standard Module Series
EC25 Hardware Design
EC25_Hardware_Design 50 / 130
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
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.
Figure 19: Reference Circuit of USB Application
Pin Name
Pin No.
I/O
Description
Comment
USB_DP
69
IO
USB differential data bus (+)
Require differential
impedance of 90
Ω
USB_DM
70
IO
USB differential data bus (-)
Require differential
impedance of 90
Ω
USB_VBUS 71
PI
USB power supply,
used for USB detection
Typical 5.0V
GND 72 Ground