User's Manual
LE920 Hardware User Guide
1vv0301026 Rev.8 2015-01-03
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights
Reserved. Page 30 of 88
NOTE:
To check if the LE920 has powered on, the hardware line PWRMON must be monitored.
When PWRMON goes high, the module has powered on.
NOTE:
Do not use any pull up resistor on the ON# line, it is internally pulled up. Using pull up
resistor may cause latch-up problems on the LE920 power regulator and improper powering
on/off of the module. The line ON# must be connected only in an open collector
configuration.
NOTE:
In this document all the lines are inverted. Active low signals are labeled with a name that
ends with "#" or with a bar over the name.
NOTE:
In order to avoid a back-powering effect it is recommended to avoid having any HIGH logic
level signal applied to the digital pins of the module when it is powered OFF or during an
ON/OFF transition.
4.3. Turning OFF the LE920
Turning off the device can be done in four different ways:
by Software command AT#SHDN
by Hardware Shutdown using pad ON/OFF#
by Hardware Unconditional Reset using the RESET#
by Hardware Unconditional Shutdown using the SHDN#
When the device is shut down by software command or by hardware shutdown, it issues to
the network a detach request that informs the network that the device will not be reachable
any more.
TIP:
To check if the device has powered off, hardware line PWRMON must be monitored. When
PWRMON goes low it can be considered the device has powered off.
NOTE:
In order to avoid a back-powering effect it is recommended to avoid having any HIGH logic
level signal applied to the digital pins of the module when it is powered OFF or during an
ON/OFF transition.