Telit Wireless Solutions HE910 - Unconditional Shutdown

HE910 Hardware User Guide
1VV0300925 Rev. 32 Page 70 of 111 2019-11-25
Unconditional Shutdown
Signal
Function
I/O
PAD
HW_SHUTDOWN*
Unconditional Shutdown of the
Module
I
R13
HW_SHUTDOWN* is used to unconditionally shutdown the HE910. Whenever this signal
is pulled low, the HE910 is reset. When the device is reset it stops any operation. After the
release of the line, the HE910 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 HE910. 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
1.9V
HW_SHUTDOWN* Input low
0V
0.35V
* 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.