Electronic Design

Low-Power Stereo Audio Codecs Maximize Battery Life

Texas Instruments unveiled two low-power stereo audio codecs for battery-operated applications, including digital still cameras and portable media players. The PCM3793 and PCM3794 audio codecs are designed to extend battery life, and offer 7-mW playback with a signal-to-noise ratio (SNR) of 93 dB.

The PCM3793 device further increases power efficiency by integrating the company’s Class-D amplifier technology, which is capable of driving 700 mW of output power per channel into an 8-Ω load. The PCM3794 has no speaker outputs, providing designers the option to use an external amplifier if desired.

The PCM379x codecs offer key features that meet the specific needs of portable consumer audio applications:

  • Notch filter with programmable center frequencies. Without a notch filter, digital camera manufacturers have had to disable zooming during video recording to prevent camera lens motor noise from disrupting the audio track.
  • Tone control. Designers can maximize audio performance for a particular type of sound using bass, treble, and mid-range equalization effects.
  • 3D enhancement. Speakers that are close together can be made to seem further apart for a richer, "wide stereo" effect.

    An on-chip, digital audio processor keeps signal processing in the digital domain. The codecs can be operated with only one power supply, and an integrated capacitor-less headphone driver reduces external component count and increases bass frequency response.

    PCM379x audio codecs support standard interfaces for audio (I2S, L-R justified, DSP) and control (I2C, SPI), as well as multiple single-ended and differential inputs and outputs (six inputs for both, with five outputs for the PCM3793 and three for the PCM3794). Additionally, inputs are selectable, and outputs can be mixed, giving designers control over a wide range of applications.

    The PCM3793 and PCM3794 stereo audio codecs are sampling now and are expected to be in production by the end of this month. Both are packaged in a standard 32-pin 5 by 5 mm2 QFN package. Pricing for the PCM3793 and PCM3794 is $4.50 and $4.25 each in 1000-unit quantities. An evaluation module is expected to be available in October 2006 that includes a PC-based interface for easily programming PCM379x devices.

    Texas Instruments

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