Power Supply - SimCom SIM5218E Hardware Design

SIM5218E Hardware Design
WCDMA
WCDMA mode
IDLE
WCDMA talk
HSPA mode HSPA IDLE
HSPA DATA
POWER DOWN Normal shutdown by sending the "AT+CPOF" command or using the
POWER_ON pin. The power management ASIC disconnects the power supply
from the base band part of the module, only the power supply for the RTC is
remained. Software is not active. The serial interfaces are not accessible.
Operating voltage (connected to VBAT) remains applied.
Minimum Use the "AT+CFUN" command can set the module to a minimum functionality
functionality mode without remove the power supply. In this case, the RF part of the module
mode (without will not work or the SIM card will not be accessible, or RF part and SIM card
remove power will be closed all, the serial interface is still accessible. The power consumption
supply) in this case is very low.

3.3 Power supply

The power supply of SIM5218E is from a single voltage source of VBAT= 3.4V...4.2V. In
some case, the ripple in a transmit 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 100µF, low
ESR) is recommended when use a Li battery. When you use a DC supply the Capacitor must be
larger one (for example 2200u/10V), 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 (0.1 µF to 1µF) ceramic in parallel,
which is illustrated as following figure. And the capacitors should put as closer as possible to the
SIM5218E VBAT pins. The following figure is the recommended circuit.
SIM5218E_HD_V1.03
Module has registered to the WCDMA network, and the
module is ready to send and receive.
Module is active in WCDMA mode. The power consumption
depends on network settings.
Module is ready for data transfer in HSPA mode, but no data is
currently sent or received. Power consumption depends on
network settings and HSPA configuration
There is data in transfer (PPP or TCP or UDP) in HSPA mode.
In this case, power consumption is related with network
settings (e.g. power control level), uplink / downlink data rates
and HSPA configuration
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11.06.2009