NB-IoT Module Series
BC66 Hardware Design
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3.5. Power Saving Mode (PSM)
Based on system performance, the module consumes an ultra-low current (maximum current: TBD) in
PSM. PSM is designed to reduce power consumption of the module and improve battery life. The
following figure shows the power consumption of the module in different modes.
P
ow
er
C
on
su
m
pt
io
n
PSM
Idle
T
ra
ns
m
is
si
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R
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tio
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T3324
T3412
TAU
UE inactive time
Idle
Figure 3: Module Power Consumption in Different Modes
The procedure for entering PSM is as follows: the module requests to enter PSM in “ATTACH REQUEST”
message during attach/TAU (Tracking Area Update) procedure. Then the network accepts the request
and provides an active time value (T3324) to the module and the mobile reachable timer starts. When the
T3324 timer expires, the module enters PSM for duration of T3412 (periodic TAU timer). Please note that
the module cannot request PSM when it is establishing an emergency attachment or initializing the PDN
(Public Data Network) connection.
When the module is in PSM, it cannot be paged and stops access stratum activities such as cell
reselection, and T3412 is still active.
When MO (Mobile Originated) data are sent or the periodic TAU timer expires, the module will exit from
PSM.
The following methods can be used to wake up the module from PSM:
PSM
In PSM, only the 32kHz RTC is working. The network is
disconnected, paging messages cannot be received either. The
module will exit from PSM when the timer T3412 times out, and it
can also be woken up from PSM by PWRKEY or PSM_EINT*. For
more details, please refer to
Chapter 3.5
.
