Sim900D Functional Diagram - SimCom SIM900D Hardware Design

functionality without removing the power supply. In this mode, the RF part of the module will not work or
mode the SIM card will not be accessible, or both RF part and SIM card will be closed, and the
serial port is still accessible. The power consumption in this mode is lower than normal
mode.
Charge-only The module will systematically enter Charge-only mode when a charger and battery are
mode connected to a switched-off SIM900D. In the mode, the module does not search for network
and has limited AT commands available. The module also can enter Charge-only mode from
Charge mode during normal operation by normally shutdown the module.
Charge mode The module will automatically go to this mode when a charger is connected to a Normal
during normal operation mode module of which battery voltage is not lower than 3.2V. Normal operation
operation mode includes: SLEEP, IDLE, TALK, GPRS IDLE and GPRS DATA.
2.3

SIM900D Functional Diagram

The following figure shows a functional diagram of SIM900D:
The GSM baseband engine
Flash
The GSM radio frequency part
The antenna interface
The other interfaces
SIM900D_Hardware Design_V2.02
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Smart Machine Smart Decision
2012-05-07