User's Manual

GE865 Hardware User Guide
1vv0300799 Rev.6 - 04/06/09
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 18 of 58
5.2 Power Consumption
The GE865-QUAD power consumptions are: (Preliminary Values)
GE865
-
QUAD
Mode
Average (
mA)
Mode description
IDLE mode
Stand by mode; no call in progress
AT+CFUN=1 23,9 Normal mode: full functionality of the module
AT+CFUN=4 22
Disabled TX and RX; module is not registered on the
network
AT+CFUN=0 or
AT+CFUN=5
2,4
Power saving: CFUN=0 module registered on the network
and can receive voice call or an SMS; but it is not possible
to send AT commands; module wakes up with an
unsolicited code (call or SMS) or rising RTS line. CFUN=5
full functionality with power saving; module registered on
the network can receive incoming calls and SMS
RX mode
GSM Receiving data mode
1 slot in downlink 52,3
2 slot in downlink 65,2
3 slot in downlink 78,6
4 slot in downlink 88,4
GSM TX and RX mode
GSM Sending data mode Min power level 78,1
Max power level 200,1
GPRS (class 10) TX and RX mode
GPRS Sending data mode Min power level 123,7
Max power level 370,8
POWER OFF
Module Powered Off
Power Off <26uA
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.
TIP: The electrical design for the Power supply should be made ensuring it will be capable of a peak current output
of at least 2 A.