Dallas, TX (Dec. 18, 2000) -- Designers of audio systems now have the flexibility to create a new level of digital sound quality with the industry's first complete, fully available digital audio solution announced today by Texas Instruments Inc. By developing the industry's only fully available true digital audio amplifier, TI now provides designers with a complete, end-to-end digital audio solution that keeps the audio signal in a digital format from the source to the speaker. By combining TI's fully Digital Audio Amplifier with its DSP technology, this digital audio solution has solved the "noise and hum" problems associated with today's conventional audio systems. Besides being ideal for home theater in a box (HTIB) systems, TI's digital audio technology will also help bring the highest sound quality to other consumer and automotive entertainment devices, such as digital headsets, PC and car audio systems, and traditional home audio mini-stereo systems (see www.ti.com/sc/msds5397u).

"TI's all-digital audio solution establishes a new paradigm in audio reproduction by transferring the experiences of high-quality audio systems into the consumer market. With this technology, the average consumer will be able to purchase home and PC audio systems with a richer, fuller and crisper sound quality that seems like the listeners are attending a live performance at one of the world's most renowned concert halls," said Harry Davoody, vice president of TI's Digital Audio Video/Imaging Business Unit. "Recognizing the value and potential of this technology for its customers, TI has formed a dedicated business to focus on the digital audio markets. With its true Digital Audio Amplifier and industry-leading DSP technologies, TI is in a unique position as the only IC supplier to offer all of the elements of a true digital audio solution that designers can order today."

According to DSP and audio market research firm Forward Concepts, the PC and home audio industries are moving away from analog-based audio systems and replacing them with new systems that are using digital audio technologies to improve the sound quality and performance.

"Digital audio technologies are driving the consumer entertainment market. With the emergence of digital audio amplifiers, the market dynamics are changing again as OEMs leverage this technology to bring the audio performance of high-quality stereo systems to the PC and home audio systems," said Will Strauss, president of Forward Concepts. "By combining its leading DSP technology with its newly developed, true Digital Audio Amplifier, Texas Instruments has clearly established itself as one of the leading suppliers of high-performance digital ICs for the audio market.

Industry's First All-Digital Audio Solution -- Available Today

The complete digital audio solution is based on hardware and software components that are all available today from TI. At the heart of the system is TI's DSP technology. When applications require decoding or additional audio processing, TI's digital audio solution will use a programmable TMS320C54x DSP and strong portfolio of algorithms to provide digital audio decoding at the speaker. This enables the host system to send digital data directly to the speakers from a CD, DVD, TV, game console, the Internet or other sources. By having a digital connection, designers avoid the power and signal losses associated with transmitting analog signals in today's audio systems. The DSP also provides audio processing for industry-standard formats, such as Dolby Digital, 3-D Surround Sound, DTS, MP3 and Advanced Audio Coding (AAC).

In applications where high-quality post-processing is required, TI has developed the TAS300x family of dedicated Digital Audio Processors that run advanced on-chip filtering algorithms, allowing on-the-fly configurable parametric equalization and speaker response correction. Designers can currently use the TAS3001 to perform these tasks together with dynamic range compression/expansion and volume, bass and treble control. TI also offers the new TAS3002, which is a digital audio processor that performs the same functions as the TAS3001, but offers an integrated 24-bit codec to help reduce board-space requirements and lower design complexity.

For interfacing with the PC, designers can use the TUSB3200 multichannel USB Streaming Controller that allows digital audio systems to connect bi-directionally to host systems via the USB used in almost all PCs and Macs. In addition, TI's digital audio solution supports the S/PDIF digital interfacing standard used in many consumer systems with the DIR1701 S/PDIF receiver. Scheduled to be available in 1Q 2001, this state-of-the-art device from TI's Burr-Brown product line allows the stable recovery of digital audio data from all S/PDIF sources, such as DVD, CD and MD players.

True Digital Amplification Is Here Today!

The final piece of the digital audio solution is TI's new true Digital Audio Amplifier, the TAS5xxx chipset family based on the Equibit technology from Toccata Technology, a company which TI acquired in March 2000. Consisting of a TAS5000 pulse-width modulator (PWM) and two TAS5100 H-bridges, this surface mount technology (SMT) chipset drives speakers digitally for greater power efficiency. The TAS5000 digital modulator takes I2S, 44.1-96 kHz, 16-24-bit data streams and processes the incoming Pulse Code Modulation (PCM) data into PWM digital data using state-of-the-art modulation techniques. The TAS5100 digital power stage is fed by the digital PWM signal directly from the TAS5000. The TAS5100 then converts the PWM signal into the desired digital power level at the speaker terminals, and the conversion into an analog signal takes place either in the speaker coil itself or is done by a simple LC filter. Other key benefits include surface mounting with no need for heat sinks or other cooling devices, even when supplying 25-Watt per channel (continuous) clean and crisp digital sound power. By not requiring bulky heat sinks, the TAS5xxx chipset greatly reduces the form factor size and power consumption by up to a factor of 10.

In addition, a key challenge in using digital audio amplifiers is the power management design. TI has a broad portfolio of high-performance power ICs that help designers address their power requirements while offering the necessary support to help speed time-to-market.

Applications In All Audio Areas

Many types of audio applications can benefit from the high quality, power efficiency and space savings in TI's all-digital audio solution. These include consumer entertainment systems, such as HTIB, DVD receivers and mini/micro systems; gaming and entertainment applications; business applications, such as speakerphones and multimedia conferencing systems; and digital headsets for all application areas. In addition, TI's all-digital audio solution will enhance automotive entertainment, reducing space and heat dissipation for manufacturers while allowing consumers to enjoy the experience of high-quality multichannel digital audio in their vehicle

Available Today

TI's complete digital audio solution is supported by thorough design documentation and test results documenting FCC electromagnetic compatibility (EMC). In high volumes only, audio designers can order the complete digital audio solution today directly from TI at the prices listed at the bottom of the page.

We all learned in thermodynamics class that 100% efficiency is impossible; it's as easy to build an amplifier with that performance as it is to build a perpetual-motion machine. In traditional audio amplifiers you'll see efficiencies in the range of 50%. However, digital amps that drive loudspeakers with pulsed waveforms rather than pure sinewaves promise to improve efficiency levels tremendously. In fact, with this announcement that all the parts needed for a complete digital amplifier system are shipping, TI says we can expect efficiencies exceeding 80%.

Driving speakers with digital waveforms and using the speakers' inherent electromechanical loading to smooth out sharp edges in the driving waveform is nothing new. The concept was shown in 1953 with the theoretical design of an analog-driven system, recalls Niels Anderskouv, strategic marketing manager for digital audio at TI. Then in the 1980s researchers started toying with the idea of using digital inputs to the system for a totally digital implementation. The first prototypes appeared in 1995, and Anderskouv reports that the Guiness Book of World Records lists 1998 as the year for the first commercial digital amplifier, which sold for $10,000. Amazingly, much the same technology today sells for a few dollars and comes on a few chips.

Just think about the implications. First, as the press release notes, there's no need for heat sinks on the surface-mount devices; printed-circuit boards are adequate to dissipate the little heat they do generate. In fact, you can drive loudspeakers and put a finger on the power-output device without having to worry about a burn, even with a sustained output of 30W rms. One obvious result is that audio amps are going to get smaller and lighter and should also cost less.

The next obvious step is to package these SMD parts into a portable device such as an MP3 player. Imagine being able to drive speakers with the output of a small handheld device, and without draining the batteries in just a few minutes. Actually, says Anderskouv, a digital audio player generally powers just a headset and not external speakers, so the output power is <1W. And while TI's existing TDAA chipset is designed for levels as high as 30W and isn't at all optimized for low-power applications, the firm is working on a dedicated chip for portable applications that you might look for in the coming year.

Obviously, there's a tremendous market opportunity here, and TI isn't alone in pursuing it. Cirrus Logic (www.cirrus.com), having acquired AudioLogic last summer, announced a very similar PWM-based technology last September but has yet to formally introduce a product portfolio. A relatively new player on the scene, Apogee Technology Inc (www.apogeeddx.com) last month announced availability of ICs based on its DDX Direct Digital Amplification technology; the DDX-2000/2060 chipset is priced at $6.98 (qty 1000) with delivery of OEM quantities expected in the first quarter of next year. But what TI boasts of is that it alone has been sampling parts for more than six months and is presently shipping volume quantities of all the chips needed to assemble a totally digital audio amplifier. And as for patents, Anderskouv says that TI has many on the algorithms and modulator, but the biggest portfolio of patents is associated with the power stage being introduced now.

Despite being digital in nature, audio performance doesn't suffer. The scheme boasts THD (total harmonic distortion) < 0.1% across a dynamic range of 90 to 110 dB at all power levels and frequencies. This contrasts to a typical value of 85 dB for the S/N ratio with standard amplifiers, says Anderskouv. He adds that TI takes its measurements at speaker terminals in actual use, not using some ideal test system that improves the specs.

I was interested in getting a few more details about current consumption. I first asked whether Vcc on the digital amplifier devices is 5V? No, actually, the DAP (digital audio processor) that converts from PCM to PWM runs on VCC = 3.3V in order to achieve low power consumption and to facilitate an easy interface with other digital ICs, such as a DSP. The TDAA stage, the power MOSFET output stage, runs on three power supplies: one for the input/control section at DVDD = 3.3V; one for the power MOSFET gate drive, PVDD1 = 18 - 22V; and one for the power MOSFET (output stage), PVDD2 = 0 - 24V depending on the application's output power level. So for 30W into a 4-ohm speaker, the TDAA chip set runs on 3.3V for the digital control section and on approximately 20V high power for the output stage.

So what's the current draw when running at 30W? Again assuming a 4-ohm speaker, 30W results in the following output current: Io = sqrt(Po / 4) = sqrt(30 / 4) = 2.74A, and peak output current is sqrt(2)*Io = 3.87A. The TDAA has a power efficiency of n = 80% in a typical application, and when delivering 30W with a Vsupp = 20V you get an rms power-supply current Isupply = Po/(n*Vsupp) = 1.875A.

However, the best thing about the TDAA technology is that when delivering less output power, such as 1/8 of maximum (3.75W), power efficiency is 6 times better than a normal Class AB amplifier -- and this assumption corresponds well with playing music where the dynamic contents is high. So in a normal application the TDAA will in average give more that six times lower power loss.

As you can imagine, the next few years are going to introduce some radical changes to the way manufacturers design and build audio equipment. As consumers, we can look forward to systems that take on a completely new look -- smaller, lighter, less expensive and better performing equipment in form factors we can't begin to imagine. I can't wait to see what's on the store shelves next Christmas!