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5.2 Power Consumption
Module supplied but Switched Off
Normal mode: full functionality of the module
Full functionality with power saving; DRX7;
Module registered on the network can receive incoming
calls and SMS
Normal mode: full functionality of the module
Module is not registered on the network
Full functionality with power saving;
DRX9 (1.3mA in case of DRX5).
WCDMA voice call (TX = 10dBm)
WCDMA data call (Cat 8, TX = 0dBm)
WCDMA data call (Cat 8, TX = 22dBm)
The GSM system is made in a way that the RF transmission is not continuous, else it is packed
into bursts at a base frequency of about 216 Hz, and the relative current peaks can be as high as
about 2A. Therefore the power supply has to be designed in order to withstand with these
current peaks without big voltage drops; this means that both the electrical design and the board
layout must be designed for this current flow. If the layout of the PCB is not well designed a
strong noise floor is generated on the ground and the supply; this will reflect on all the audio
paths producing an audible annoying noise at 216 Hz; if the voltage drop during the peak current
absorption is too much, then the device may even shutdown as a consequence of the supply
voltage drop.
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