NATIONAL SEMICONDUCTOR ANNOUNCES 2W BOOMER? AUDIO POWER AMPLIFIER WITH FULL SET OF PERFORMANCE-ENHANCING FEATURES FOR DESKTOP AND LAPTOP COMPUTERS

September 1, 1998 - National Semiconductor Corporation? today introduced the latest addition to its line of Boomer audio power amplifiers for desktop and laptop computers. The LM4835 generates 2W of power and incorporates a special suite of design features that includes stereo driver stages for speakers and headphones, internal DC volume control, bass boost, and docking station/line level outputs.

"With its high level of power and integration and small package size, the LM4835 is ideal for both desktop and laptop computer audio systems," said Parviz Ghaffaripour, National's audio product line director. "It was developed after partnering with several major laptop PC manufacturers. In addition to meeting their requirements, it turns out that the LM4835 is also well suited for audio systems in multimedia monitors, small portable TV designs and a variety of PDAs," he added.

Key advantages of the LM4835 audio power amplifier include:

• A stereo bridged audio power amplifier stage that generates up to 2W of output power into a 4-ohm speaker with less than 1.0% 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 0.1% THD+N.
• Stereo docking station/line level outputs producing less than 0.004%THD+N at 1kHz.
• A DC volume control that saves money by using a low-cost external potentiometer in place of a costly audio-grade potentiometer. When operating with powered speakers or a docking station, a control pin can be used to bypass the volume control.
• A bass boost feature gives the system designer the option of enhancing the output of the internal speakers with selectable gain.

Power-saving features include a shutdown mode that reduces power consumption to 0.7?A (typ), extending the operating time of battery-powered systems. An input for "system beep" allows critical system warnings to be heard in the event headphones are plugged in but not in use.

Like other recent Boomer audio amplifiers from National, the LM4835 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.

Price and Availability
The LM4835MTE is currently available in a 28-pin TSSOP with exposed DAP (die attach pad) that is priced at $3.25 in quantities of 1000. The LM4835MT (1-watt version) in a standard 28-pin TSSOP package is priced at $3.00. For more information on the LM4835, visit our website at http://www.national.com/pf/LM/LM4835.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, Calif., 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 www.national.com.

###
AU98005