SARA-G450 - System integration manual
UBX-18046432 - R08
System description
Page 24 of 143
C1-Public
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The Internal reset signal is not available on a module pin, but the host application can monitor the
V_INT pin to sense the start of the module power-on sequence.
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Before the switch-on of the generic digital interface supply source (V_INT) of the module, no
voltage driven by an external application should be applied to any generic digital interface of the
module.
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Before the modules are fully ready to operate, the host application processor should not send any
AT command over the AT communication module interfaces. After V_INT rises up, wait at least
5 s before issuing AT commands; during this time, modules might be responsive but the NVM
might not be ready yet for set commands.
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The duration of SARA-G450 modules switch-on routine can vary depending on the
application / network settings and the concurrent module activities.
1.6.2
Module power-off
1.6.2.1
Switch-off events
The SARA-G450 modules can be properly switched off by:
AT+CPWROFF command (more details in the u-blox AT commands manual
The current parameter settings are saved in the module’s non-volatile memory and a clean network
detach is performed: this is the correct way to switch off the modules.
An abrupt hardware shutdown occurs on SARA-G450 modules when a low level is applied to PWR_OFF
input. In this case, the current parameter settings are not saved in the module’s non-volatile memory
and a clean network detach is not performed.
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It is highly recommended to avoid an abrupt hardware shutdown of the module by forcing a low
level on PWR_OFF input pin during module normal operation: the PWR_OFF line should be set low
only if reset or shutdown via AT commands fails or if the module does not reply to a specific AT
command after a time period longer than the one defined in the u-blox AT commands manual
An abrupt under-voltage shutdown occurs on SARA-G450 modules when the VCC module supply is
removed. In this case, the current parameter settings are not saved in the module’s non-volatile
memory and a clean network detach cannot be performed.
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It is highly recommended to avoid an abrupt removal of VCC supply during module normal
operation: the power-off procedure must be properly started by the application, by using the
+CPWROFF AT command, waiting the command response for an appropriate time period (see the
u-blox AT commands manual
), and then an appropriate VCC supply must be held at least until
the end of the module’s internal power-off sequence, which occurs when the generic digital
interfaces supply output (V_INT) is switched off by the module.
An over-temperature or an under-temperature shutdown occurs on SARA-G450 modules when the
temperature measured within the cellular module reaches the dangerous area, if the optional Smart
Temperature Supervisor feature is enabled and configured by the dedicated AT command. For more
details, see section
and the u-blox AT commands manual
, +USTS AT command.
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The smart temperature supervisor feature is not supported by the “00” product version.
