User's Manual

LE920 Hardware User Guide

1vv0301026 Rev.0 - draft4 – 2013-05-

GSM900 PL5 255

EDGE Sending data mode

DCS1800 PL0 240

* Worst/best case depends on network configuration and is not under module control.

TIP:

The electrical design for the Power supply must be made ensuring that it will be capable of a

peak current output of at least 2A.

In GSM/GPRS mode, RF transmission is not continuous and 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 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; this will reflect on all the audio paths producing an audible

annoying noise at 216 Hz; if the voltage drops during the peak, current absorption is too

much. The device may even shut down as a consequence of the supply voltage drop.