User's Manual

HE910 Hardware User Guide

1vv0300925 Rev.9 – 07-02-2012

5.2 Power Consumption

The HE910 power consumptions are described in the following table

(Preliminary values):

HE910

Mode

Average

(mA)

Mode description

Stand by mode (WCDMA)

Stand By 3G

1.2*

Disabled TX and RX; module is not registered on the

network; DRX7

IDLE mode (GSM)

Stand By 2G

1.1*

Disabled TX and RX; module is not registered on the

network, DRX5

Operative mode (WCDMA)

WCDMA Voice

538

WCDMA voice call (23.5dBm; High Band)

HSDPA

557

HSDPA data call (23.5dBm; High Band, CAT10)

Operative mode (GSM)

CSD TX and RX mode

GSM VOICE CALL

GSM900 CSD PL5

209

DCS1800 CSD PL0

176

* depending on network configuration and not under module control.

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.

NOTE:

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.