LTE-A Module Series
EG06 Hardware Design
EG06_Hardware_Design 46 / 89
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 &
USB 3.0 specifications.
It is important to route the USB signal traces as differential pairs with total grounding. The impedance
of USB differential trace i
s 90Ω.
For USB 3.0 routing traces, the length matching of Tx and Rx differential pairs should be less than
0.7mm.
Do not route signal traces under crystals, oscillators, magnetic devices, PCIe 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 2.0pF for USB 2.0, and less than 0.4pF for
USB 3.0.
Keep the ESD protection components to the USB connector as close as possible.
If possible, reserve a 0R resistor on USB_DP and USB_DM lines.
“*” means under development.
3.11. UART Interfaces
The module provides three UART interfaces: the main UART interface, the debug UART interface, and
the BT UART interface. The following shows their features.
The main UART interface supports 4800bps, 9600bps, 19200bps, 38400bps, 57600bps, 115200bps,
230400bps, 460800bps and 921600bps baud rates, and the default is 115200bps. This interface is
used for data transmission and AT command communication.
The debug UART interface supports 115200bps baud rate. It is used for Linux console and log
output.
The BT UART interface supports 115200bps baud rate. It is used for BT communication.
The following tables show the pin definition.
Table 11: Pin Definition of the Main UART Interface
Pin Name
Pin No.
I/O
Description
Comment
RI
61
DO
Ring indicator
1.8V power domain
NOTE