National Semiconductor Announces Fully Compliant AC '97 Audio Codec For Multimedia PCs

June 1, 1998 - National Semiconductor Corporation?, co-author of Audio Codec '97 common architecture standard for PC audio devices, today introduced a fully integrated stereo audio codec that meets or exceeds all baseline AC'97 and PC98 requirements.

The LM4545 includes a number of industry-leading performance specifications. Its high-resolution 18-bit sigma-delta codec design is instrumental in achieving high-fidelity sound that exceeds AC'97 requirements. Analog S/N (signal-to-noise ratio), at 96dB for CD to line out, is the best in the industry. Digital S/N is 92dB for D/A and 90dB A/D. In addition, with National's proprietary 3D-sound circuitry, the LM4545 creates stirring audio presence with "surround" sound realism.

"The demand for quality PC sound in multimedia designs is growing," said Bob Ghaffari, National's senior audio marketing manager. "The LM4545 is well positioned for emerging applications requiring new levels of audio performance, such as scalable audio for 3-D games, CD and DVD playback and eventually full duplex video and audio conferencing," he added.

The combination of an integrated "Baby Boomer®" stereo headphone driver with dedicated volume control makes National's codec ideal for laptop applications where space limitations preclude a power amplifier on the board. A synchronous, fixed rate serial bus allows connection of the AC '97 controller to the LM4545. Moreover, the device saves system power since it is compatible with both 3.3V and 5V digital supplies.

About AC '97
The AC '97 standard, defined by a consortium of Intel, ADI, Yamaha, Creative Labs and National Semiconductor, was first announced in May 1996. Reversing the trend toward integration of analog and digital audio circuitry on a single chip, AC '97 calls for two separate chips - one mixed-signal, the other purely digital. Significantly higher levels of performance and design flexibility are made possible by separating the mixed-signal and digital sections. For example, placing analog inputs and outputs physically close to audio connectors minimizes unwanted coupling of noisy digital system signals. Similarly, separation of the digital audio controller from the analog codec allows significant improvements in signal-to-noise ratio. Finally, AC '97's serial interface permits digital docking, a very attractive feature to notebook manufacturers.

Price and Availability
The LM4545VH, housed in a 48-pin TQFP (thin quad flatpack), is priced at $7.00 in quantities of 1000. It is available now in production quantities. For more information on the LM4545, visit our website at http://www.national.com/pf/LM/LM4545.html.

National Semiconductor Corporation produces system-on-a-chip silicon solutions for the information highway, based on its leadership in analog and mixed signal technologies. National is headquartered in Santa Clara, California, and focuses on the communications, personal systems and consumer markets. National has annual sales of approximately $2.5 billion and 13,000 employees worldwide. Additional company and product information is available on the World Wide Web at http://www.national.com.