SIM340 Hardware Design
GPRS
STANDBY
Module is ready for GPRS data transfer, but no data is
currently sent or received. In this case, power consumption
depends on network settings and GPRS configuration.
GPRS DATA There is GPRS data in transfer (PPP or TCP or UDP). In this
case, power consumption is related with network settings (e.g.
power control level), uplink / downlink data rates and GPRS
configuration (e.g. used multi-slot settings).
POWER DOWN
Normal shutdown by sending the “AT+CPOWD=1” command or using the
PWRKEY. The power management ASIC disconnects the power supply from
the base band part of the module, and only the power supply for the RTC is
remained. Software is not active. The serial port is not accessible. Operating
voltage (connected to VBAT) remains applied.
Minimum
functionality
mode (without
remove power
supply)
Use the “AT+CFUN” command can set the module to a minimum functionality
mode without remove the power supply. In this case, the RF part of the module
will not work or the SIM card will not be accessible, or both RF part and SIM
card will be closed all, and the serial port is still accessible. The power
consumption in this case is very low.
Alarm mode
RTC alert function launches this restricted operation while the module is in
POWER DOWN mode. SIM340 will not be registered to GSM network and
only parts of AT commands can be available.
3.3 Power supply
The power supply of SIM340 is from a single voltage source of VBAT= 3.4V...4.5V. In some
case, the ripple in a transmitting burst may cause voltage drops when current consumption rise to
typical peaks of 2A. So the power supply must be able to provide sufficient current up to 2A.
For the VBAT input, a local bypass capacitor is recommended. A capacitor (about 100 µF, low
ESR) is recommended. Multi-layer ceramic chip (MLCC) capacitors can provide the best
combination of low ESR and small size but may not be cost effective. A lower cost choice may be
a 100 µF tantalum capacitor (low ESR) with a small (0.1µF to 1µF) ceramic in parallel, which is
illustrated as following figure. The capacitors should put as close as possible to the SIM340
VBAT pins. The following figure is the recommended circuit.
SIM340_HD_V3.09
18.03.2009
22
