Rainbow Electronics GM862-QUAD-PY - Manual (Page 21)

GM862-QUAD / PY Hardware User Guide
1vv0300748 Rev. 5 - 20/09/07
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 21 of 68
6 Power Supply
The power supply circuitry and board layout are the most important part in the full product design and
they strongly reflect on the product overall performances, hence read carefully the requirements and
the guidelines that will follow for a proper design.
6.1 Power Supply Requirements
POWER SUPPLY
Nominal Supply Voltage 3.8 V
Max Supply Voltage 4.2 V
Supply voltage range 3.4 V - 4.2 V
CONSUMPTIONS
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
7,20 / 3,56 2
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
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, 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.
1 Worst/best case depends on network configuration and is not under module control