TI Home > News Releases

News Releases

National Semiconductor’s New Boomer Audio Amplifiers Consistently Deliver 1.0W and 1.8W Output Power Even as Battery Voltage Drops to 3V

Full Power at Low Voltage: National Technology Maintains Voice and Ringtones

Aug 9, 2005

August 9, 2005 - Two new single-chip Boomer® audio amplifiers from National Semiconductor Corporation (NYSE:NSM) deliver up to 1.8 Watts (W) of output power to mobile phone and portable devices regardless of the battery’s voltage.

National’s LM4804 and LM4805 deliver 1.8W and 1W output power, respectively, when the battery is charging, fully charged or running low on power (minimum 3V voltage). These chips increase the battery voltage internally to automatically provide constant high voltage to the embedded audio amplifier.  In addition, these continuously high-power, single-chip packages simplify discrete or multi-chip approaches to bring both space and cost savings to the customer.

"Some handset volumes have the annoying trait of getting quieter and quieter as battery voltage drops – especially for high-power speaker phone applications," said Mike Polacek, vice president of National Semiconductor’s Audio group.  “National’s LM4804 and LM4805 are unique products for the audio marketplace. These devices supply high power for high output volume, even while phone batteries drop to their lowest operable levels. This is a great feature that end users appreciate."

High Output Power
National’s LM4804 is capable of creating 1.8W of power to an 8-Ohm bridge-tied-load (BTL) from any input voltage between 3V and 4.6V with less than 1 percent total harmonic distortion plus noise (THD+N). 

National’s LM4805 is a boosted audio power amplifier designed for driving 8-Ohm speakers in portable applications.  It delivers at least 1W of continuous power to an 8-Ohm load from any input voltage between 3V and 4.6V with less than 2 percent THD+N.

Neither amplifier requires bootstrap capacitors or snubber circuits, reducing external components and size.  Both devices feature a micro-power shutdown mode and an internal thermal shutdown protection mechanism, as well as advanced pop and click circuitry that eliminates output transients which would otherwise occur during power or shutdown cycles.  The LM4804 and LM4805 are also unity-gain stable and have externally configurable gain using simple gain-setting resistors.

Pricing and Availability
Available now, the LM4804 is priced at $2 and the LM4805 is priced at $1.90, both in 1,000-unit quantities.  Both chips are offered in 28-pin standard or lead-free LLP® packages. More information on the products is available at http://www.national.com/pf/LM/LM4804.html and http://www.national.com/pf/LM/LM4805.html
.  A large selection of audio amplifiers is supported by National’s WEBENCH® online design tool.  To explore these solutions, visit http://webench.national.com.  To learn about high-performance audio amplifiers for portable applications, visit National’s library of online seminars

Note to editors: To view a high-resolution downloadable photo of the new products, visit National's photo gallery at http://www.national.com/company/pressroom/gallery/audio.html.

About National’s Audio Portfolio
National Semiconductor works with every major handset maker in the world and is the leading provider of audio amplifier systems for the cell phone market.  The company’s line of Boomer audio amplifiers enhances and enriches the entire range of sound – from voice, ring sounds and music – that can be amplified in a mobile phone.  National manufactures Class AB and Class D mono and stereo speaker amplifiers, mono and stereo headphone amplifiers, and audio subsystems for desktop and notebook computers, multimedia displays and portable electronic devices.  The company also offers its higher-power Overture® amplifiers for consumer stereo and home theater systems.  For more information on National’s audio products, visit http://audio.national.com.

About National Semiconductor
National Semiconductor, the industry's premier analog company, creates high-value 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 analog markets include wireless handsets, displays and a variety of broad electronics markets, including medical, automotive, industrial, and test and measurement applications. Headquartered in Santa Clara, California, National reported sales of $1.91 billion for fiscal 2005, which ended May 29, 2005.  Additional company and product information is available at www.national.com