SARA-G450 - System integration manual
UBX-18046432 - R08 System description Page 25 of 143
C1-Public
1.6.2.2 Switch-off sequence by AT+CPWROFF
Figure 13 describes the SARA-G450 modules power-off sequence, properly started sending the
AT+CPWROFF command, allowing storage of the current parameter settings in the module’s
non-volatile memory and a clean network detach, with the following phases:
When the +CPWROFF AT command is sent, the module starts the switch-off routine.
The module replies OK on the AT interface: the switch-off routine is in progress.
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), except the RTC
supply (V_BCKP).
Then, the module remains in power-off mode as long as a switch-on event does not occur
(e.g. applying an appropriate low level to the PWR_ON input), and enters not-powered mode if the
supply is removed from the VCC pins.
VCC
V_BCKP
PWR_ON
PWR_OFF
V_INT
Internal reset
System state
Digital pins state Operational
AT+CPWROFF
sent to the module
Figure 13: SARA-G450 modules power-off sequence description
☞ 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 SARA-G450 modules power-off sequence.
☞ The VCC supply can be removed only after the end of the module internal switch-off routine. After
the V_INT voltage level has gone low, wait at least 3 s before removing VCC.
☞ The duration of each phase in the SARA-G450 modules switch-off routines can largely vary
depending on the application / network settings and the concurrent module activities.
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