Telit Wireless Solutions LM940 Design Guide

LM940 Hardware Design Guide
1VV0301352 Rev. 18 Page 46 of 75 2022-01-04
Not Subject to NDA
6.6.3. Control Signals
The LM940 supports the following control signals:
• W_DISABLE_N
Below table lists the control signals of LM940.
Pin
Signal
I/O
Function
Type
Comment
20
W_DISABLE_N
I
RF disable (airplane mode)
1.8V
Table 29: Module Control Signal
6.6.3.1. W_DISABLE_N
The W_DISABLE_N signal is provided to make the LM940 goes into the airplane mode:
• Enter the airplane mode: Low
• Normal operating mode: High or Leave the W_DISABLE_N not connected
LM940 contains an internal VBATT (Nominal 3.3V) pull-up resistor on W_DISABLE_N.
6.6.3.2. WAN_LED_N
The WAN_LED_N signal drives the LED output.
The recommended WAN_LED_N connection is the following:
Figure 17: Recommended WAN_LED_N Connection
R1 and VDD determine the brightness of LED and forward current.
When VDD is 3.3V and LED’s forward voltage is 2.0V, it is recommended to use the value
of R1 from 66 ohm to 250 ohms.
But please determine it in considering the specification of the LED to use.
Note/Tip: If enable the LED function and connect the LED to the
WAN_LED_N pin, current consumption may be increased.

Telit Wireless Solutions LM940 Specifications

General

Brand	Telit Wireless Solutions
Model	LM940
Category	Wireless modules
Language	English