ST keeps mobile music playing with power-saving stereo headphone amplifier

GENEVA, SWITZERLAND: STMicroelectronics, a leading provider of semiconductor solutions for mobile devices, has introduced a stereo headphone amplifier IC that achieves significantly higher efficiency than previous-generation devices, enabling listeners to enjoy high-quality sound for longer between battery charges.

The TS4621 delivers the high audio performance of a traditional analog amplifier, and saves power by operating from a lower supply voltage for the majority of audio-signal levels. While connected to two supplies, power is drawn from the higher-voltage rail for only those brief periods when peak audio power levels are required. By using this principle, known as class G, the TS4621 is among the first such headphone amplifiers targeting portable applications.

The TS4621 simplifies system design with features including an industry-standard I2C interface enabling digital volume control from -60dB to +4dB, and integrated switch-on/switch-off circuitry that eliminates pop and click noise. Its ultra-small 1.65mm x 1.65mm chip-scale package allows the amplifier to be positioned very close to the headphone connector for optimum audio performance.

Joining ST's portfolio of audio ICs targeting products such as cellphones, multimedia and MP3 players, game terminals and GPS devices, the TS4621 has four-times lower quiescent current consumption than the existing TS4601; a class AB amplifier. This saving is valuable in energy-sensitive applications such as battery-powered devices. At the same time, the TS4621 excels in key audio performance parameters to deliver an outstanding listening experience for end users.

Major features of the TS4621:
* 0.006 percent THD+N at 1kHz;
* 100dB PSRR at 217Hz (high immunity to GSM signaling noise);
* 100dB SNR at 0dB gain;
* 0.6mA/channel quiescent current;
* 2.1mA/channel active current at 100microW audio output.

The TS4621 is sampling to lead customers now and will be available for production orders from April 2010, priced from $0.95 for orders over 1,000 units.