User's Manual

LE910 Hardware User Guide
1vv0301089 Rev.3 – 09-06-2014
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 47 of 79
Signal
Function
I/O
PAD
HW_SHUTDOWN*
Unconditional Shutdown of the Module
I
R13
HW_SHUTDOWN* is used to unconditionally shutdown the LE910. Whenever this signal is
pulled low, the LE910 is reset. When the device is reset it stops any operation. After the release
of the line, the LE910 is unconditionally shut down, without doing any detach operation from
the network where it is registered. This behaviour is not a proper shut down because any GSM
device is requested to issue a detach request on turn off. For this reason the HW_SHUTDOWN*
signal must not be used to normally shutting down the device, but only as an emergency exit in
the rare case the device remains stuck waiting for some network response.
The HW_SHUTDOWN* is internally controlled on start-up to achieve always a proper power-
on reset sequence, so there's no need to control this pin on start-up.
It may only be used to reset a device already on that is not responding to any command.
NOTE:
Do not use this signal to power off the LE910. Use the ON/OFF signal to perform this function
or the AT#SHDN command.
Unconditional Shutdown Signal Operating levels:
Signal
Min
Max
HW_SHUTDOWN*
Input high
1.5V
2.1V
HW_SHUTDOWN*
Input low
0V
0.5V
* this signal is internally pulled up so the pin can be left floating if not used.
If unused, this signal may be left unconnected. If used, then it must always be connected with
an open collector transistor, to permit to the internal circuitry the power on reset and under
voltage lockout functions.