Digital audio SoC family enables cooler new flat-panel TV designs

August 05, 2011 // Paul Buckley

STMicroelectronics has released two new Sound Terminal digital-audio system-on-chip ICs for home-entertainment applications, which will enable smaller new-product designs while also running cooler to help designers meet tough product-safety requirements.

Home-entertainment innovations such as flat-panel TVs and music docks enable consumers to enjoy room-filling audio without needing a roomful of audio equipment. ST’s Sound Terminal system-on-chip ICs have taken a leading role in enabling new generations of smaller, slimmer products by combining digital audio processing, speaker drivers and other functions on a single chip. ST’s Sound Terminal ICs are now used in about 30% of the flat-panel TVs sold worldwide, based on data from market analyst iSuppli.

The new STA381BW and STA381BWS are optimized for flat-panel TVs and enable designers to reduce pc-board sizes further by consolidating a headphone driver, line-driver output, and an independent digital-to-analog converter (DAC). These functions typically require three additional ICs. The integrated DAC provides an extra analog output that can be connected to the headphone input or to an external circuit, and uses ST’s F3X technology to simplify external filtering. The headphone driver and industry-standard 2Vpp line out, which require no DC blocking capacitors, also save external components and hence maximize reductions in pc-board size and manufacturing costs.

In addition, the STA381BW and STA381BWS deliver best-in-class thermal performance through a combination of high energy efficiency, proprietary ternary PWM modulation and enhanced package design, enabling lower operating temperatures. This simplifies thermal management, helping to ensure that the TV’s chassis temperature meets product safety criteria such as UL or CE specifications. The STA381BW and STA381BWS can deliver up to 15 W output power (24 V, 8 ohm load), maintaining the IC’s temperature at 55.4°C.

As members of the Sound Terminal family, the new devices implement digital signal processing and speaker-driver circuitry applying ST’s Full Flexible Amplification (FFX) technology. FFX combines 2.1-channel audio processing with a digitally controlled class-D power stage operating at up to 94% efficiency. The audio processor also features STSpeakerSafe, STCompressor as well as STSpeakerTune speaker compensation, which boosts audio quality from flat-panel TV speakers while preventing damage due to over-driving.

The STA381BW and STA381BWS are sampling now to lead customers, and are available in the 48-pin VQFN 7 x 7 x 1 mm package, priced from $3.00 for the STA381BWS and $4.00 for the STA381BW for 1000-piece orders.

Visit STMicroelectronics at www.st.com.

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