SARA-G450 - System integration manual
UBX-18046432 - R08
System description
Page 19 of 143
C1-Public
1.5.1.3
VCC current consumption in cyclic idle/active mode (+UPSV enabled)
The power saving configuration is disabled by default, but it can be enabled using the appropriate AT
command (see the u-blox AT commands manual
, +UPSV AT command). When power saving is
enabled, the module automatically enters low power idle mode whenever possible, reducing current
consumption.
During idle mode, the module processor runs with an internal 32 kHz reference clock.
When the power saving configuration is enabled and the module is registered or attached to a
network, the module automatically enters the low power idle mode whenever possible, but it must
periodically monitor the paging channel of the current base station (paging block reception), in
accordance with the 2G system requirements, even if connected mode is not enabled by the
application. When the module monitors the paging channel, it wakes up to the active mode to enable
paging block reception. In between, the module switches to low power idle mode. This is known as
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.
For 2G radio access technology, the paging period varies from 470.8 ms (DRX = 2, length of 2 x 51 2G
frames = 2 x 51 x 4.615 ms) up to 2118.4 ms (DRX = 9, length of 9 x 51 2G frames = 9 x 51 x 4.615 ms).
roughly describes the current consumption profile of SARA-G450 modules, 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.
20-30 ms
IDLE MODE
ACTIVE MODE
IDLE MODE
Active Mode
Enabled
Idle Mode
Enabled
0.44-2.09 s
IDLE MODE
20-30 ms
ACTIVE MODE
Time [s]
Current [mA]
100
50
0
Time [ms]
Current [mA]
100
50
0
RX
Enabled
DSP
Enabled
Figure 8: VCC current consumption profile versus time of the SARA-G450 modules, when registered with the network, with
power saving enabled: the very low power idle mode is reached and periodical wake up to active mode are performed to
monitor the paging channel
For the detailed modules VCC current consumption values in low-power idle mode or in cyclic
idle/active mode (module registered with 2G network with power saving enabled), see the SARA-G450
data sheet
