User's Manual

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L850-GL Hardware User Manual Page
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Figure 3-5 Timing Control for Start-up
Note:
The VSD2_1V8 signal is the internal PMU 1.8V output voltage which is not connected to the M.2
interface. The above timing of VSD2_1V8 is only for reference.
The RESET# is required to pull high with a t
on1
delay after the +3.3V, because it takes some time
tocharge thecapacitors for +3.3V power supply. If the +3.3V power supply is already stable
before starting upthe module, the delay time can be ignored.
3.3.2 Module Shutdown
The module can be shut down by the following controls:
Shutdown Control
Action
Condition
Software
Sending AT+CPWROFF command
Normal shutdown(recommend)
Hardware
Pull down
FUL_CARD_POWER_OFF# pin
Only used whena hardware exception occurs
and the software control cannot be used.
The module can be shut downby sending AT+CPWROFF command. When the module receives the
software shutdown command, the module will start the finalization process (the reverse process of
initialization), andit will be completed after 3s. In the finalization process, the module will save the network,
SIM card and some other parameters from memory, then clear the memory and PMU will be powered off.
After shutdown, the VSD2_1V8 voltage is also shut down. The software control timing isshown in Figure
3-6: