LTE Standard Module Series
EC25 Hardware Design
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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 90Ω
USB_DM 70 IO USB differential data bus (-)
Require differential
impedance of 90Ω
USB_VBUS 71 PI
USB power supply,
used for USB detection
Typical 5.0V
GND 72 Ground
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