SIM900 Hardware Design
3 Application Interface
SIM900 is equipped with a 68-pin SMT pad that connects to the cellular application platform. Sub-interfaces
included in these SMT pads are described in detail in following chapters:
z Power supply (please refer to Chapter 3.3
)
z Serial interfaces (please refer to Chapter 3.8
)
z Analog audio interfaces (please refer to Chapter 3.9
)
z SIM interface (please refer to Chapter 3.10
)
Electrical and mechanical characteristics of the SMT pad are specified in Chapter 5.
3.1 SIM900 Pin Description
Table 5: Pin description
Power Supply
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS COMMENT
VBAT I 3 VBAT pins are dedicated to
connect the supply voltage.
The power supply of
SIM900 has to be a single
voltage source of VBAT=
3.1V...4.8V. It must be able
to provide sufficient current
in a transmit burst which
typically rises to 2A
Vmax= 4.8V
Vmin=3.1V
Vnorm=4.0V
VRTC I/O Current input for RTC when
the battery is not supplied for
the system.
Current output for backup
battery when the main
battery is present and the
backup battery is in low
voltage state.
Vmax=3.15V
Vmin=2.0V
Vnorm=3.0V
Iout(max)= 300uA
Iin=2 uA
If RTC backup
is needed, a
battery or
capacitor
should be
connected with
the VRTC pin..
If RTC backup
is not needed, a
capacitor
should be
connected to
this pin.
SIM900_HD_V1.05 06.23.2010
17
To Next Page
Loading...
Need help?
General