User's Guide

UC864-E-AUTO / AWS-AUTO Hardware User Guide
1vv0300795 Rev.11 – 2010/11/18
Reproduction forbidden without Telit Communications S.p.A’s. written authorization - All Rights Reserved. Page 23 of 78
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.
TIP:
TIP: TIP:
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.