LN920 HW Design Guide
1VV0301730 Rev. 1
Page 43 of 81
2021-08-11
Not Subject to NDA
USB 3.0 needs AC coupling series capacitors on the TX lines in both directions. In order
to interface USB3.0 with the application board controlling the modem, 0.1uF capacitors
should be installed on USB_SS_RX_P/M lines of the LN920. Series capacitors are
already placed on USB_SS_TX_P/M lines inside LN920 module.
Note:
The USB signal traces must be carefully routed: minimize
trace lengths, number of vias, and capacitive loading. The impedance
value should be as close as possible to 90 Ohms differential.
Below table lists the USB interface signals.
PIN
Signal
I/O
Function
NOTE
7
USB_D+
I/O
USB2.0 DATA Plus
9
USB_D-
I/O
USB2.0 DATA Minus
29
USB3.0_TX-
O
USB3.0 super-speed
transmit
–
Minus
31
USB3.0_TX+
O
USB3.0 super-speed
transmit
–
Plus
35
USB3.0_RX-
I
USB3.0 super-speed
receive
–
Minus
37
USB3.0_RX+
I
USB3.0 super-speed
receive
–
Plus
Table 20: Available Signals
Note:
Consider placing a low-capacitance ESD protection component
to protect the LN920 against ESD spikes
