M10 Hardware Design
M10_HD_V3.0 - 26 -
Alarm mode RTC alert function launches this restricted operation while the module is in
POWER DOWN mode. The module will not be registered to GSM network
and only parts of AT commands can be available.
1) Use the EMERG_OFF pin only while failing to turn off the module by the command
“AT+QPOWD=1” and the ON/OFF pin. Please refer to Chapter 3.4.2.4.
3.3. Power supply
The power supply range of M12 is from 3.3V to 4.6V which is supplied with a single voltage
source of VBAT. 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 1.6A.
A reference design of DC 5V/2A input power source is shown in Figure 3. The designed output for
the power supply is 4.16V, 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 preferable for its better efficiency especially with the 1.6A peak current in burst mode of
the module.
Figure 3: Reference circuit of the source power supply input
The RF Power Amplifier current (1.6A peak in GSM/GPRS mode) flows with a ratio of 1/8 of
time, around 577us every 4.615ms, in talking mode. The following figure is the VBAT voltage
and current ripple at the maximum power transmitting phase, the test condition is VBAT=4.16V,
VBAT maximum output current is 1.6A, C3=100µF tantalum capacitor (ESR=0.7Ω).
To Next Page
Loading...
Need help?
General
