User's Manual

SARA-R4 series - System Integration Manual
UBX-16029218 - R03 System description
Page 19 of 94
Figure 7 describes the SARA-R4 series modules switch-off sequence started by means of the PWR_ON input pin,
allowing storage of current parameter settings in the module’s non-volatile memory and a proper network
detach, with the following phases:
 A low pulse with appropriate time duration (see SARA-R4 series Data Sheet [1]) is applied at the PWR_ON
input pin.
 At the end of the switch-off routine, all the digital pins are tri-stated and all the internal voltage regulators
are turned off, including the generic digital interfaces supply (V_INT).
 Then, the module remains in power-off mode as long as a switch on event does not occur (e.g. applying a
proper low level to the PWR_ON input ), and enters not-powered mode if the supply is removed from the
VCC pins.
VCC
PWR_ON
RESET_N
V_INT
Internal Reset
System State
BB Pads State
OFF
Tristate / Floating
ON
Operational -> Tristate
Operational
0 s
~2.5 s
~5 s
The module starts
the switch-off routine
VCC can be
removed
Figure 7: SARA-R4 series switch-off sequence by means of PWR_ON pin
The Internal Reset signal is not available on a module pin, but the application can monitor the V_INT pin
to sense the end of the switch-off sequence.
The duration of each phase in the SARA-R4 series modules’ switch-off routines can largely vary depending
on the application / network settings and the concurrent module activities.