Usb Interface - Quectel BG96 Mini PCIe Hardware Design

3.5. USB Interface

The following table shows the pin definition of USB interface.
Table: Pin Definition of USB Interface
Pin No. Pin Name
36 USB_DM
38 USB_DP
BG96 Mini PCIe is compliant with USB 2.0 specification. It can only be used as a slave device. Meanwhile,
it supports high speed (480Mbps) mode and full speed (12Mbps) mode. The USB interface is used for AT
command communication, data transmission, GNSS NMEA output, software debugging, firmware
upgrade. The following figure shows a reference circuit of USB interface.
Module
USB_DM
USB_DP
GND
A common mode choke L1 is recommended to be added in series between the module and customer's
MCU in order to suppress EMI spurious transmission. Meanwhile, the 0Ω resistors (R3 and R4) should be
added in series between the module and the test points so as to facilitate debugging, and the resistors are
not mounted by default. In order to ensure the integrity of USB data line signal, L1/R3/R4 components
must be placed close to the module, and also these resistors should be placed close to each other. The
extra stubs of trace must be as short as possible.
The following principles should be complied with when design the USB interface, so as to meet USB 2.0
specification.
BG96_Mini_PCIe_Hardware_Design
I/O Description
IO USB differential data (-)
IO USB differential data (+)
Minimize these stubs
R3
R4
L1
Close to Module
Figure 6: Reference Circuit of USB Interface
BG96 Mini PCIe Hardware Design
Comment
Require differential impedance of 90Ω
Require differential impedance of 90Ω
Test Points
NM_0R
NM_0R
ESD Array
LTE Module Series
MCU
USB_DM
USB_DP
GND
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