Quectel BC66 Hardware Design page 21

UE inactive time
Figure 3: Module Power Consumption in Different Modes (Modem)
When the modem remains in PSM and the AP is in idle mode, the module will enter Deep Sleep mode.
The procedure of the modem entering PSM is as follows:
The modem 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 modem and the mobile reachable timer starts. When the T3324 timer expires, the modem 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 Deep Sleep mode, it will be woken up in either of the following cases:

When the T3412 timer times out, the module will exit Deep Sleep automatically.

Lifetime timeout for LwM2M session.

Upon detection of a falling edge on PSM_EINT, the module will be woken up from Deep Sleep, and
the timing is illustrated below.
BC66_Hardware_Design
Idle
T3324
VBAT
PSM_EINT
VDD_EXT
Module
OFF
Status
Figure 4: Timing of Waking up Module from Deep Sleep
PSM
T3412
TAU
4ms
RUNNING
NB-IoT Module Series
BC66 Hardware Design
Idle
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