Power amp brings extra dimension to handset audio

Compact audio power amplifier creates 3D audio effects in the stereo speaker outputs to add impact and a surround-sound feel to MP3 and video files.

A compact audio power amplifier chip for mobile phones and for other portable audio products creates 3D audio effects in the stereo speaker outputs to add impact and a surround-sound feel to MP3 and video files.

The TS4997 can deliver 1.2W per channel of continuous average output power into 8ohm loads, from a 5V supply - although it operates from supplies of as little as 2.7V - while its high-efficiency design and ultralow standby power will help extend battery life.

Mobile phones increasingly offer media features such as FM radio, MP3 player, video player and videophone.

The TS4997 is an ideal solution that can enhance the performance of such functions, in addition to providing a high- quality stereo amplifier.

It delivers an impressive stereo effect from a very small platform, and is also suitable for PDAs and for other portable audio devices.

ST's analogue 3D technology, which is integrated in the TS4997, is the simplest in the market; no signal pre-processing is required, and it needs no external components to be added to the compact 4mm square package, minimising space requirements and ensuring low production cost.

A two-pin digital interface controls the 3D effect through independent gain adjustments for each audio channel, and additional left and right channel standby mode pins allow the supply current to be cut to less than 10nA per channel.

The amplifier chip operates on a 2.7 to 5.5V power supply, providing excellent immunity to supply interference with 85dB PSRR.

Signal-to-noise ratio (SNR) is a high 106dB(A), and pop and click interference is suppressed.

The device is part of ST's large portfolio of audio amplifiers designed for portable applications such as mobile phones and laptop PCs.

The TS4997 is available now in a QFN16 4 x 4mm package, with 0.65mm pad pitch, priced at US $1.20 in quantities of 1000 pieces.

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