LTE Module Series
BG96 Hardware Design
BG96_Hardware_Design 36 / 78
USB_DP
USB_DM
GND
USB_DP
USB_DM
GND
R1
R2
Close to Module
R3
R4
Test Points
ESD Array
NM_0R
NM_0R
0R
0R
Minimize these stubs
Module
MCU
USB_VBUS
VDD
Figure 14: Reference Circuit of USB Application
In order to ensure signal integrity of USB data lines, components R1, R2, R3 and R4 must be placed
close to the module, and also should be placed close to each other. The extra stubs of traces 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.
It is important to route the USB signal traces as differential pairs with total grounding. The impedance
of USB differential trace is 90
Ω.
Do not route signal traces under crystals, oscillators, magnetic devices and RF signal traces. It is
important to route the USB differential traces in inner-layer with ground shielding on not only upper
and lower layers but also right and left sides.
Pay attention to the influence of junction capacitance of ESD protection components on USB data
lines. Typically, the capacitance value should be less than 2pF.
Keep the ESD protection components as close to the USB connector as possible.
BG96 module can only be used as a slave device.
3.10. UART Interfaces
The module provides three UART interfaces: UART1, UART2 and UART3 interfaces. The following are
their features.
NOTE
