ML8011 GSM GPRS Modem User’s Manual
Page 7
GSM IDLE
Software is active. The module has registered to the
GSM network, and the module is ready to send and
receive.
GSM TALK
GSM connection is going. In this mode, the power
consumption is decided by the configuration of Power
Control Level (PCL), dynamic DTX control and the
working RF band.
GPRS IDLE
The module is not registered to GPRS network. The
module is not reachable through GPRS channel.
GPRS
STANDBY
The module is registered to GPRS network, but no
GPRS PDP context is active. The SGSN knows the
Routing Area where the module is located at.
GPRS
READY
The PDP context is active, but no data transfer is going
on. The module is ready to receive or send GPRS data.
The SGSN knows the cell where the module is located
at.
GPRS DATA
There is GPRS data in transfer. In this mode, power
consumption is decided by the PCL, working RF band
and GPRS multi-slot configuration.
POWER
DOWN
Normal shutdown by sending the
“
AT+QPOWD=1
”
command, using the
PWRKEY pin. The power management ASIC disconnects the power
supply from the base band part of the module, and only the power supply
for the RTC is remained. Software is not active. The serial interfaces are
not accessible. Operating voltage (connected to VBAT) remains applied.
Minimum
functionality
mode (without
removing power
supply)
Use the
“
AT+CFUN
”
command can set the module to a minimum
functionality mode without removing the power supply. In this case, the
RF part of the module will not work or the SIM card will not be
accessible, or both RF part and SIM card will be closed all, but the serial
port is still accessible. The power consumption in this case is very low.
3.3 Power supply (VBAT)
The power supply of the module is from a single voltage source of VBAT= 3.6V...4.6V. The
GSM transmitting burst can cause obvious voltage drop at the supply voltage thus the power
supply must be carefully designed and is capable of providing sufficient current up to 2.0A.
The circuit design of the power supply for the module largely depends on the power source.
Figure 2 shows a reference design of +5V input power source. The designed output for the power
supply is 4.0V, thus a linear regulator can be used. If there
’
s a big voltage difference between the
input source and the desired output (VBAT), a switching converter power supply would be
