Electronic Design

Digital Music Chip Plays MP3, WMA, And AAC Audio Files

By implementing an extended software stack, austriamicrosystems' AS3520 music decoder IC becomes a self-contained digital audio player that's small enough to fit in a mobile phone. It requires just one-third the component count of any competitor, occupies the smallest board area of any off-the-shelf solution, and has the lowest system cost. Currently, no other single-chip player in the sub-$10 category (for 10,000 units) can play MP3, WMA, and AAC, as well as offer ADPCM and additional user-defined codecs.

An on-chip digital equalizer eliminates the acoustic restrictions. A powerful internal amplifier drives earphones as well as stereo speakers at up to 1 W. The music chip comes in a 100-contact 10- by 10- by 1.2-mm CTBGA package and supports all standard sampling rates from 8 to 48 kHz. Moreover, it can play back MP3 files at up to 320 kbits/s and WMA and AAC files at up to 256 kbits/s.

A self-configuring dc-dc converter allows use of any supply voltage between 1.0 and 5.5 V. Three separate built-in regulators handle internal analog and digital circuitry, as well as external auxiliary devices (e.g., FM radio). The internal CPU clock rate (up to 50 MHz) and core supply voltage (down to 2.25 V) are programmable on-the-fly. This feature will automatically run the device at minimum power consumption in each functional state. Play time is typically 10 hours when operated from a single AAA battery.

Input sensitivity and gain control can be programmed in three ranges to support microphones and line input levels. Designed for worldwide use, the AS3520 handles diverse character sets, including Chinese, Korean, and Japanese text. A full reference design is available.

austriamicrosystems AG

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