User Manual

GM862-QUAD / PY Hardware User Guide

1vv0300748 Rev. 5 - 20/09/07

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

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.

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