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National Semiconductor Introduces Two Single-Chip Boomer Integrated Audio Subsystems with Expanded Feature Sets

LM4859 and LM4931 Audio Subsystems Save Space and Increase Functionality

Nov 2, 2004

November 2, 2004 - National Semiconductor Corporation (NYSE:NSM), originator of best-in-class Boomer® audio technology, today launched two Boomer audio subsystems that provide a wide variety of features for cellular phones and portable applications.  The LM4859 compact subsystem integrates the audio amplifiers, volume control, mixer, power management control, 3D sound enhancement and I2C control all into a single, space-saving package.  The full-featured LM4931 contains a stereo I2S DAC, on-board phase-locked-loop (PLL), a voice band codec, stereo headphone amplifier, Class D mono speaker amplifier, microphone pre-amplifier and sidetone generator, all with an I2C or SPI digital control interface.  I2C/SPI control allows selection of a variety of operating modes, volume control, and other performance functions.

"National's LM4859 and LM4931 integrated audio subsystems provide everything our customers need," said Gary Adrig, marketing director for National Semiconductor’s audio products group.  "These audio subsystems give customers a huge feature set in a very compact space.  By integrating all of the features that a customer might need into a single package, the LM4859 and LM4931 provide space and system cost savings without sacrificing performance.  These subsystems give customers the outstanding audio clarity and functionality that National’s Boomer product family is known for."

Incredible Integration with Minimal Software Required
National's LM4859 is an integrated audio subsystem that operates on a 2.7-5.5V supply.  It combines a stereo speaker amplifier that delivers 495mW per channel into an 8 Ohm load, and a stereo headphone amplifier that delivers 25mW per channel into a 32 Ohm load with a 3.3V power supply.   In addition, the LM4859 routes and mixes the stereo and mono inputs into 16 distinct output modes using a simple I2C compatible interface.  Other features include an ultra-low current shutdown mode and thermal shutdown protection.

National's LM4931 is an integrated audio subsystem that supports voice and digital audio functions.  The full range I2S music path features a signal-to-noise ratio of 86dB with an 18-bit, 48kHz input.  The high efficiency Class D speaker amplifier delivers 470mW into 8 Ohms and the headphone amplifier delivers 26mW root means square (RMS) to a 32 Ohm single-ended stereo load with less than one percent total harmonic distortion plus noise (THD+N) with a power supply of 3.3V.  Additionally, the LM4931 has advanced circuitry to reduce power consumption and controller overhead, and to eliminate pop and click noise.

Unlike hard to use audio codecs that require sophisticated software development for operation and control, both the LM4931 and LM4859 use a standard I2C or SPI compatible interface. Simple I2C or SPI commands are used to set one of the operating modes and volume level for any given audio amplifier. The operating modes are predetermined to cover all of the functional needs required in portable applications. The LM4931 has 10 preset operating modes, while the LM4859 has extra modes for the 3D feature for a total of 16. These modes not only make the devices easy to use but also allow the user to turn off unused amplifiers to optimize system power management.

About National's Audio Portfolio
Working with every major handset maker in the world, National Semiconductor is the leading provider of audio amplifier systems for the cell phone market.  The company's line of Boomer audio amplifier products enhance and enrich the entire range of sound – from voice, ring sounds and music – that can be amplified in a mobile phone.  National also manufactures Class AB and Class D mono and stereo speaker amplifiers, mono and stereo headphone amplifiers and audio subsystems for desktop and notebook computers, displays, consumer and other portable electronic devices, as well as consumer stereo and home theater systems.  For more information on National’s audio products, visit

Pricing and Availability
The LM4859 is available now in a 28-lead LLP® packaging and is priced at $1.80, and the LM4931 is available now in a 42-bump micro SMD packaging and is priced at $3.99, both in 1,000-unit quantities.  More information on the LM4859 is available at http://www.national.com/pf/LM/LM4859.html
, and more information on the LM4931 is available at http://www.national.com/pf/LM/LM4931.html  For an introduction to audio subsystems, visit National’s library of online seminars at http://www.national.com/onlineseminar/#audio.  To view a high-resolution downloadable photo of the LM4859 and LM4931, visit National's photo gallery at http://www.national.com/company/pressroom/gallery/audio.html.

About National Semiconductor
National Semiconductor, the industry's premier analog company, creates high performance analog devices and subsystems.  National's leading-edge products include power management circuits, display drivers, audio and operational amplifiers, communication interface products and data conversion solutions. National's key markets include wireless handsets, displays, PCs and laptops.  The company's analog products are also optimized for numerous applications in a variety of electronics markets, including medical, automotive, industrial, and test and measurement.  Headquartered in Santa Clara, California, National reported sales of $1.98 billion for fiscal 2004, which ended May 30, 2004.  Additional company and product information is available at www.national.com