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National Semiconductor Introduces Filter-less High Efficiency Class D Boomer® Audio Amplifier

Jan 26, 2004

January 26, 2004 - National Semiconductor Corporation (NYSE:NSM), originator of best-in-class Boomer audio technology, today introduced a filter-less high efficiency Boomer audio amplifier for cellular phones and portable consumer devices. 

National’s LM4667 is ideal for portable consumer applications such as cellular handsets because of its high efficiency, resulting in less system heat and longer battery life.  It is housed in a tiny micro SMD package.  The LM4667’s fixed gain reduces pin count and eliminates the need for an output filter when it is located near the speaker, resulting in both space and cost savings.

“Eliminating the output filter reduces the number of parts and board area, which simplifies the circuit design for our customers,” said Gary Adrig, marketing director for National Semiconductor’s audio products group.  “Since many consumers now use cellular phones as their primary phones, talk times are increasing, which creates the need for longer battery life.  National’s LM4667 fulfills this need by delivering high efficiency, lower operating temperature, and longer battery life.”

National’s LM4667 is a fully integrated single-supply, high efficiency switching audio amplifier.  It features an innovative modulator that eliminates the output filter used with typical switching amplifiers.  The LM4667 processes analog inputs with a delta-sigma modulation technique that lowers output noise and total harmonic distortion plus noise (THD+N) when compared to conventional pulse width modulators.

The LM4667 is designed to meet the demands of mobile phones and other portable communications devices.  Operating on a single 3V supply, it is capable of driving 8Ohm transducer loads at a continuous average output of 450mW with less than 1% THD+N.  Its flexible power supply requirements allow operation from 2.7V to 5.5V. 

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, stereo, and headphone audio 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 http://www.national.com/appinfo/audio/

Pricing and Availability
The LM4667 is available now in 9-bump micro SMD packaging and is priced at $0.48 in 1,000-unit quantities.  More information on the LM4667 is available at http://www.national.com/pf/LM/LM4667.html
.  To view a high-resolution downloadable photo of the LM4667, 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, imaging sensors and data conversion solutions. National's key markets include wireless handsets, displays, PCs, networks and a broad range of portable applications. With headquarters in Santa Clara, California, National reported sales of $1.67 billion for fiscal 2003, which ended May 25, 2003. Additional company and product information is available at www.national.com