LPWA Module Series
BG770A-GL Hardware Design
BG770A-GL_Hardware_Design 39 / 75
Keep the placement of (U)SIM card connector as close to the module as possible. Keep the trace
length as less than 200 mm as possible.
Keep (U)SIM card signals away from RF and VBAT traces.
Assure the ground 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 ground shielded.
To offer good ESD protection, it is recommended to add a TVS diode array with parasitic capacitance
not exceeding 15 pF. In order to facilitate debugging, it is recommended to reserve series resistors
for the (U)SIM signals of the module. 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 line can improve anti-jamming capability when long layout trace
and sensitive occasion are applied, and should be placed close to the (U)SIM card connector.
3.10. USB Interface*
BG770A-GL contains one integrated Universal Serial Bus (USB) interface which complies with the USB
2.0 specification and supports operation at full-speed (12 Mbps) mode only. The USB interface is under
development, it is not recommended to use at present. The following table shows the pin definition of USB
interface.
Table 12: Pin Definition of USB Interface
For more details about USB 2.0 specification, visit http://www.usb.org/home.
Pin Name
Pin No.
I/O
Description
Comment
USB_VBUS
12
AI
USB connection detect
Input range: 1.19–2.0 V
USB_DP
11
DIO
USB differential data (+)
Require differential
impedance of 90 Ω
USB_DM
10
DIO
USB differential data (-)
USBPHY_3P3
42
PI
Power supply for USB PHY
circuit
Vnom = 3.3 V
USBPHY_3P3_EN
64
DO/PU
External
LDO
enable
control for USB
1.8 V power domain
GND
43
Ground
