NATIONAL SEMICONDUCTOR ANNOUNCES NEWEST TWO WATT STEREO BOOMER AUDIO AMPLIFIER

New Device Strengthens National's Position as Dominant Audio Amplifier Supplier to the Notebook PC Market

July 12, 1999 - National Semiconductor Corporation? (NYSE: NSM) today introduced the LM4836, the newest member of the company's line of Boomer? audio power amplifiers for notebook computers, strengthening National's position as the dominant supplier of the most comprehensive audio amplifier solutions for the notebook PC market. The LM4836 adds an input mux capability to the Boomer line's full feature set that includes 2W of power per channel, headphone mode, internal DC volume control, bass boost and docking station/line level outputs. The input mux increases system performance by allowing the CD to be played while the rest of the notebook PC is off.

"Our customers identified an input mux as a requirement for their next-generation systems, so we developed the LM4836 to meet their design needs," said Ken Boyce, marketing manager for the audio product line. "The LM4836 offers a comprehensive feature set, and superior performance and price, for all of our customers' future notebook PC audio amplifier requirements."

Rich Feature Set Makes Audio Systems Sing
National maintains its leadership position in the audio amplifier market through close customer partnerships and the continuous enhancement of the features and performance of its Boomer line. With the addition of the input mux, the LM4836 builds upon the popular LM4835. Key advantages of the new LM4836 include:

• An input mux that allows the CD player to operate while the rest of the system is shut off.
• A DC volume control that uses a cost-effective standard potentiometer in place of a costly, audio-grade potentiometer, with no performance tradeoffs.
• A bass boost feature that automatically pumps up the bass when headphones are detached from the system's jack. Notebook PC systems typically do not have good bass response, so the bass boost capability automatically adjusts between headphone mode and speaker mode to provide a richer, more equalized sound.
• A stereo bridged audio power amplifier stage that generates up to 2W of output power per channel into 4-ohm speakers with less than 1.0 percent THD+N (total harmonic distortion plus noise), while consuming a minimal amount of supply current.
• A stereo headphone driver that produces 85mW per channel with less than 1.0 percent THD+N.
• Stereo docking station/line level outputs that produce less than 0.065 percent THD+N at 1kHz.
• PC98 and PC99 compliance as required by Microsoft.

Power-saving features include a shutdown mode that reduces power consumption to 0.7?A (typical), extending the operating time of battery-powered systems. An input for "system beep" allows critical system warnings to be heard if headphones are plugged in, but not in use, or the volume is turned all the way down or muted.

Like other Boomer audio amplifiers from National, the LM4836 features circuitry to suppress the "pops and clicks" often associated with turn-on and turn-off. It also operates without the aid of bootstrap capacitors or snubber networks. A minimal number of external components is needed, greatly simplifying overall system design, saving board space and reducing manufacturing costs.

Innovative Packaging
In systems with 4-ohm speakers requiring two watts of power, the LM4836 (MTE package) employs innovative exposed die attached pad (DAP) packaging that protects the device from overheating. The exposed DAP is a thermal pad that is attached to the device to dissipate heat from the chip onto the board. This type of packaging is key to the elimination of any audio amplifier overheating problems that can be associated with higher-powered notebook systems.

Price and Availability
The LM4836MTE (2W version) is currently available in a TSSOP-28 package with exposed DAP for $3.00 each in quantities of 1K. The LM4836MT (1W version) in a standard TSSOP-28 package is $2.70 each in quantities of 1K. For more information on the LM4836, visit http://www.national.com/pf/LM/LM4836.html.

About National
National Semiconductor provides system-on-a-chip solutions for the information age. Combining real-world analog and state-of the-art digital technology, the company's chips lead many sectors of the personal computer, communications, and consumer markets. With headquarters in Santa Clara, California, National has annual sales of $2 billion and 11,500 employees worldwide. Additional company and product information is available on the World Wide Web at www.national.com.