LE940B6 HW User Guide
Rev. 2.02
Page 47 of 111
2020-01-10
5.
Hardware Commands
Turning on the LE940B6 Module
To turn on the LE940B6 module, the ON_OFF_N pad must be asserted low in the range
of 80 - 120 milliseconds and then released.
Figure 3 illustrates a simple circuit to power on the module using an inverted buffer output.
Figure 3: Power-on Circuit
GND
R1
R2
Q1
Power ON Impulse
80ms < Hold Time < 120ms
ON_OFF_N
NOTE:
In case VBATT needs to be removed and applied again. The application
must take into account the decay time of the power supply after VBATT is
removed. VBATT input must be at zero volt before VBATT is reapplied.
Initialization and Activation State
After turning on the LE940B6 module, a predefined internal boot sequence performs the
HW and SW initialization of the module, which takes some time to complete fully. During
this process, the LE940B6 is not accessible.
As shown in Figure 4, the LE940B6 becomes operational at least 25 seconds after
PWRMON goes HIGH.
NOTE:
During the Initialization state, AT commands are not available. The DTE host
must wait for the Activation state prior to communicating with the LE940B6.
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