User's Guide

LE920A4 HW User Guide Hardware Commands
Doc#: 1VV0301261 Initialization and Activation State
Rev. 4.7.1 Page 47 of 124 2019-11-21
Figure 4: Module Initialization and Activation
NOTE:
During SW initialization of the module, the SW configures all pads and
interfaces to their desired mode. When PWRMON goes high, this indicates
that the initialization of all I/O pads is completed.
NOTE:
To check whether the module has completely powered on, monitor the
SW_RDY hardware line. When SW_RDY goes high, the module has
completely powered on and is ready to accept AT commands.
NOTE:
Do not use any pull-up resistor on the ON_OFF line as it is internally pulled
up. Using a pull-up resistor may cause latch-up problems on the module’s
power regulator and improper powering on/off of the module. The ON_OFF
line must be connected only in an open collector configuration.
NOTE:
For systems not requiring controlled power ON/OFF, automatic power on can
be supported by shorting the ON_OFF signal directly GND. In this case, the
module will start power on sequence immediately after VBATT supply is
applied
1 Sec < T_Hold < 2 Sec
VBATT
ON_OFF
SW_RDY
T_RDY < 20 Sec
V_AUX
PWRMON
18 Sec < T_PWRMON < 20 Sec
OFF State Initialization State Active State
OK to Send AT
commands
All interfaces and pins
configured