Step-down converter increases battery life

Paul Boughton

AnalogicTech has introduced the AAT1171, a fully integrated voltage-scaling dc/dc step-down converter specifically optimised to control the power to the power amplifier (PA) in WCDMA and CDMA handsets.

By dynamically controlling the operating voltage of the PA in mobile phones, the AAT1171 increases amplifier efficiency and extends talk time.

The stereotypical WCDMA handset transmit profile makes the PA operate at approximately +16dBm output power for about 50 to 60 per cent of its operating life.

When powered from the AAT1171, instead of being powered directly from the battery, the PA consumes 60 percent less power at this +16dBm level. This energy saving enables longer battery life, smaller batteries, and thus smaller and lighter mobile phones.

The AAT1171 operates across a wide voltage input range of 2.7V to 5.5V. Its input voltage is controlled by a real-time output signal from the baseband processor and delivers up to 600mA of continuous load current.

By supplying a variable output voltage of 0.6V to 3.6V, the AAT1171 optimises PA efficiency at both low and high transmit levels.

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