u-blox SARA-G3 Series System Integration Manual page 31

SARA-G3 series - System Integration Manual
1.5.1.3 VCC current consumption in cyclic idle/active-mode (power saving enabled)
The power saving configuration is by default disabled, but it can be enabled using the appropriate AT
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command (refer to [2], AT+UPSV command). When power saving is
enabled, the module automatically enters idle-mode whenever possible, reducing current consumption.
During idle-mode, the module processor runs with 32 kHz reference clock frequency. For SARA-G350
modules, the internal oscillator automatically generates the 32 kHz clock. For SARA-G300 and SARA-
G310 modules, a valid 32 kHz signal must be properly provided to the EXT32K input pin of the module
to let idle-mode, that otherwise cannot be reached (this is not needed for the other SARA-G3 series
modules).
When power saving is enabled, the module is registered or attached to a network and a voice or data
call is not enabled, the module automatically enters idle-mode whenever possible, but it must periodically
monitor the paging channel of the current base station (paging block reception), in accordance to GSM
system requirements. When the module monitors the paging channel, it wakes up to active-mode, to
enable the reception of paging block. In between, the module switches to idle-mode. This is known as
GSM discontinuous reception (DRX).
The module processor core is activated during the paging block reception, and automatically switches its
reference clock frequency from 32 kHz to the 26 MHz used in active-mode.
The time period between two paging block receptions is defined by the network. This is the paging period
parameter, fixed by the base station through broadcast channel sent to all users on the same serving cell.
The time interval between two paging block receptions can be from 470.76 ms (DRX = 2, i.e. width of
2 GSM multiframes = 2 x 51 GSM frames = 2 x 51 x 4.615 ms) up to 2118.42 ms (DRX = 9, i.e.
width of 9 GSM multiframes = 9 x 51 frames = 9 x 51 x 4.615 ms).
Figure 7Figure 7 roughly describes the current consumption profile of SARA-G350 modules, or specifically
of SARA-G300 / SARA-G310 modules when their EXT32K input pin is fed by an external 32 kHz signal
SARA-G3 series Data Sheet
with characteristics compliant to the one specified in [1], when power saving
is enabled. The module is registered with the network, automatically enters the very low power idle-mode,
and periodically wakes up to active-mode to monitor the paging channel for paging block reception.
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