LPWA Module Series
BG950A-GL&BG951A-GL_Hardware_Design
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Keep the placement of (U)SIM card connector as close to the module as possible. Keep the trace
length less than 200 mm.
Keep (U)SIM card signals away from RF and VBAT traces.
Assure the ground trace between the module and the (U)SIM card connector short and wide. Keep
the trace width of ground and USIM_VDD no less than 0.5 mm to maintain the same electric
potential. Make sure the bypass capacitor between USIM_VDD and USIM_GND less than 1 μF,
and place it as close to (U)SIM card connector as possible. If the system ground plane is complete,
USIM_GND can be connected to the system ground directly.
To avoid cross-talk between USIM_DATA and USIM_CLK, keep them away from each other and
shield them with surrounded ground. USIM_RST should also be surrounded with ground.
To offer good ESD protection, it is recommended to add a TVS diode array with parasitic
capacitance not exceeding 15 pF. It is recommended to reserve 0 Ω series resistors for the (U)SIM
signals of the module to facilitate debugging. The 33 pF capacitors are used for filtering interference
of EGSM900. Note that the (U)SIM peripheral circuit should be close to the (U)SIM card connector.
The pull-up resistor on USIM_DATA trace can improve anti-jamming capability when long layout
trace and sensitive occasions are applied, and should be placed close to the (U)SIM card
connector.
4.2. USB Interface
*
BG950A-GL/BG951A-GL provides one integrated Universal Serial Bus (USB) interface which complies
with the USB 2.0 specification and supports full speed mode only. USB interface is used AT command
communication, data transmission, software debugging and firmware upgrade.
The following table shows the pin definition of USB interface.
Table 13: Pin Definition of USB Interface
It is recommended to reserve test points for debugging and firmware upgrading in your designs.
Pin Name
Pin No.
I/O
Description
Comment
USB_VBUS
8
AI
USB connection detect
Typ. 5.0 V
USB_DP
9
AIO
USB differential data (+)
Compliant with USB 2.0 standard
specification. Require differential
impedance of 90 Ω.
USB_DM
10
AIO
USB differential data (-)