National Semiconductor Introduces High-Performance Boomer? Stereo Audio Power Amplifier for Laptop Computers

New IC Delivers 2.1W per Channel from a 5V Source; Operates Down to 2V

June 12, 1998 - National Semiconductor Corporation? today announced that it has added a high-performance audio amplifier for multimedia laptop computers to its family of high-efficiency, quality-sound Boomer audio amplifiers. Using a 5V supply, the LM4873 generates up to 2.1W per channel to a 4 ohm load with less than 1.0% THD (total harmonic distortion) at 1kHz. National's device powers stereo headphones from a single-ended mode, or stereo speakers from a dual bridge speaker drive. This solution also features an input select mux that allows toggling between two sets of stereo amplifier inputs.

"The LM4873 offers a great combination of high output power and design flexibility,in the smallest package available," said Bob Ghaffari, National's senior audio marketing manager. "With this single device, designers can replace two mono power amplifiers, a headphone amplifier and the switching circuitry required to switch between headphone and speaker modes - saving cost, board space and design time."

The LM4873 has conventional 1/8-inch stereo headphone connector, enabling operation in the single-ended mode to drive stereo headphones. Power consumption is just 8mA of supply current while in the active mode. Only 0.7mA is consumed in the power-saving shutdown/mute mode, extending operating time of battery-powered systems. The LM4873 operates between 2.0 and 5.5V, making it ideal for portable applications.

As the latest addition to National's family of Boomer audio amplifiers, the LM4873 features circuitry to suppress the "pops and clicks" often associated with turn-on. It also operates without the aid of bootstrap capacitors or snubber networks. A minimal number of external components, combined with the product's small 20-pin footprint, greatly simplifies overall system design, saves board space and lowers manufacturing costs. An internal thermal shutdown mechanism protects the device from overheating, making it virtually indestructible.

Price and Availability
The LM4873 is currently available in a standard 20-pin TSSOP (thin small shrink outline package). It is also available in a TSSOP with an exposed DAP (die-attached pad) that allows greater heat dissipation than a standard TSSOP. In quantities of 1000, the LM4873MT is priced at $2.10. The LM4873MTE (with exposed DAP) is $2.20.

For more information on the LM4873, visit our website at http://www.national.com/pf/LM/LM4873.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, California, 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.