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SIM548C Hardware Design
3 GSM application interface
All hardware interfaces except RF interface that connects SIM548C to the customers’ cellular
application platform is through a 60-pin 1.27mm
pitch board-to-board connector. Sub-interfaces
included in this board-to-board connector are described in detail in following chapters:
z
Power supply and charging control
z
GSM serial interface
z
Two analog audio interfaces
z
SIM interface
Electrical and mechanical characteristics of the board-to-board connector are specified in
Chapter
6.
There are also ordering information for mating connectors.
3.1 Pin description
Table 5: Board-to-Board connector pin description
Power Supply
PIN NAME
I/O
DESCRIPTION
DC CHARACTERISTICS
VBAT
4 VBAT pins of the board-to-board
connector are dedicated to connect
the supply voltage. The power supply
of the GSM part of 548C has to be a
single voltage source of VBAT=
3.4V...4.5V. It must be able to provide
sufficient current in a transmitting
burst which typically rises to
2A.mostly. These 4 pins are voltage
input
Vmax= 4.5V
Vmin=3.4V
Vnorm=4.0V
VRTC
I/O
RTC current input from the backup
battery when the VBAT is not
supplied for the system.
Current output to backup battery
when the main battery is present and
the backup battery is low voltage
state.
Vmax=2.0V
Vmin=1.2V
Vnorm=1.8V
I
out(max)
= 20uA
I
in
=5 uA
VCHG
I
Voltage input for the charge circuit;
making the system detect the charger.
Vmax=5.25V
Vmin=1.1 * VBAT
Vnorm=5.1V
SIM548C_HD_V1.01
09.05.2008
19