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L850-GL Hardware User Manual Page 27 of 54
Index
Minimum
Typical
Notes
t
pr
-
-
+3.3V power supply rises time. If power supply always ready,
there is no t
pr
t
on1
10ms
30ms
If the RESET# has a residual voltage, then 30ms is necessary
t
on2
10ms
30ms
PERST# should de-asserted after FULL_CARD_POWER_OFF#
3.3.2 Module Shutdown
The module can be shut down by the following controls:
Shutdown Control Action
Condition
Software
Sending AT+CFUN=0 command
Normal shutdown(recommend)
Hardware
Pull down
FULL_CARD_POWER_OFF# pin
Only used when a hardware exception occurs
and the software control cannot be used.
The module can be shut down by sending AT+CFUN=0 command. When the module receives the
software shutdown command, the module will start the finalization process (the reverse process of
initialization), and it will be completed after t
sd
time(t
sd
is the time which AP receive OK of “AT+CFUN=0”, if
there is no response, the max t
sd
is 5s). In the finalization process, the module will save the network, SIM
card and some other parameters from memory, then clear the memory and shut down PMU. The software
control timing is shown in Figure 3-6:
+3.3V
PERST#
t
pd
RESET#
Module State
Finalization
Activation
FULL_CARD_POWER_OFF#
t
off2
t
sd
OFF
AT+CFUN=0
t
off1
Figure 3-6 Software control power off timing
Index Minimum Typical Maxim Notes
t
pd
10ms
100ms
-
+3.3V power supply goes down time. If power supply is always
on, there is no t
pd
t
off1
10ms
30ms
-
RESET# should asserted before FULL_CARD_POWER_OFF#
t
off2
0ms
30ms
t
off1
PERST# should asserted after RESET#