Telit Wireless Solutions LM940 Design Guide

LM940 Hardware Design Guide
1VV0301352 Rev. 18 Page 43 of 75 2022-01-04
Not Subject to NDA
Warning: At power-up, LM940 success to enumerate SS_USB
interface. But if a hot plug is attempted in case of SS_USB, then
LM940 may fail to enumerate SS_USB.
Below table lists the USB interface signals.
Pin
Signal
I/O
Function
Type
Comment
38
USB_D+
I/O
USB 2.0 Data Plus
Analog
36
USB_D-
I/O
USB 2.0 Data
Minus
Analog
33
USB_SS_RX_P
I
USB 3.0 super-
speed receive –
plus
Analog
31
USB_SS_RX_M
I
USB 3.0 super-
speed receive –
minus
Analog
25
USB_SS_TX_P
O
USB 3.0 super-
speed transmit –
plus
Analog
23
USB_SS_TX_M
O
USB 3.0 super-
speed transmit –
minus
Analog
Table 27: USB Interface Signals
Note: Even if USB communication is not used, it is still highly
recommended to place an optional USB connector on the application
board.
At least test points of the USB signals are required since the USB
physical communication is needed in the case of SW update.
Note: Consider placing a low-capacitance ESD protection component
to protect LM940 against ESD strikes
If an ESD protection should be added, it is suggested to connect it as follows:

Telit Wireless Solutions LM940 Specifications

General

Brand	Telit Wireless Solutions
Model	LM940
Category	Wireless modules
Language	English