UMTS/HSDPA Module
UC15 Hardware Design
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3.12. USB Interface
UC15 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, software debug and firmware
upgrade. The following table shows the pin definition of USB interface.
Table 18: USB Pin Description
Pin Name
Pin No.
I/O
Description
Comment
USB_DP
62
IO
USB differential data bus (positive).
Require differential
impedance of 90
Ω
.
USB_DM
63
IO
USB differential data bus (minus).
Require differential
impedance of 90
Ω
.
USB_VBUS 64
PI
Used for detecting the USB interface
connected.
4.75~5.25V.
Typical 5.0V.
More details about the USB 2.0 specifications, please visit
Figure 27: Reference Circuit of USB Application
In order to ensure the USB interface design corresponding with the USB 2.0 specification, please comply
with the following principles.