Application Interface; Sim900D Pin Description - SimCom SIM900D Hardware Design

SIM900D Hardware Design

3 Application Interface

SIM900D is equipped with a 48-pin SMT pad that connects to the cellular application platform. Sub-interfaces
included in these SMT pads are described in detail in following chapters:
Power supply and charging control (please refer to Chapter 3.3 and 3.5)
Serial interface and Debug interface (please refer to chapter3.9)
Two analog audio interfaces (please refer to Chapter 3.10)
SIM interface (please refer to Chapter 3.11)
Electrical and mechanical characteristics of the SMT pad are specified in Chapter 5.

3.1 SIM900D Pin Description

Table5: Pin description
Power Supply
PIN NAME I/O DESCRIPTION
VBAT I 2 VBAT pins are dedicated to
connect the supply voltage.
The
SIM900D has to be a single
voltage source of VBAT=
3.2V...4.8V. It must be able
to provide sufficient current
in a transmit burst which
typically rises to 2A
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.
VCHG I Voltage input for the charge
circuit, as the signal to detect
the charger insertion。
GND Ground
Power on or power off
SIM900D_Hardware Design_V1.04
DC CHARACTERISTICS
Vmax= 4.8V
Vmin=3.2V
power supply of Vnorm=4.0V
Vmax=3.15V
Vmin=2.0V
Vnorm=3.0V
Iout(max)= 200uA
Iin= 3uA
Vmax=7.5V
Vmin=4.5V
Vnorm=5.0V
18
COMMENT
Do not keep pin
open, it should
be connected to
a battery or a
capacitor.
If unused keep
open.
2010.10.09