User's Manual

UE910 3G HARDWARE USER GUIDE 1vv0301171 Rev.3 • 2015-04-17 36 of 78
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5.4 Unconditional Shutdown
HW_SHUTDOWN* is used to unconditionally shutdown the UE910. Whenever this signal is pulled low,
the UE910 is reset. When the device is reset it stops any operation. After the release of the line, the
UE910 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 WCDMA device is requested to
issue a detach request on turn off. 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.
To unconditionally shutdown the UE910, the pad HW_SHUTDOWN* must be tied low for at least 200
milliseconds and then released.
The signal is internally pulled up so the pin can be left floating if not used.
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.
PIN DESCRIPTION
Signal
Function
I/O
PAD
HW_SHUTDOWN*
Unconditional Shutdown of the Module
I
R13
OPERATING LEVELS
Signal Status
Min
Max
HW_SHUTDOWN* Input high
1.5V
1.9V
HW_SHUTDOWN* Input Low
0V
0.35V
WARNING:
The hardware unconditional Shutdown must not be used during normal
operation of the device since it does not detach the device from the network. It
shall be kept as an emergency exit procedure.