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FIRST STEREO-BRIDGED AUDIO POWER AMPLIFIER ALTERNATELY POWERS COMPUTER SPEAKERS OR HEADPHONES

National Semiconductor's Low-Voltage, 1.5W/channel Boomer® Stereo Driver Replaces Three Separate Amps in Most Designs

Nov 19, 1996

November 19, 1996 National Semiconductor Corporation® today announced the latest addition to its family of high-efficiency, CD-quality-sound Boomer audio amplifiers. The dual bridge-connected LM4863 audio amplifier is specifically designed for laptop or desktop computer sound systems, and is also well suited for powered speakers or portable video games. The device alternately drives stereo headphones or stereo speakers, with up to 1.5W per channel as a speaker driver.

"The LM4863 offers a universal audio amplifier solution, especially to the portable PC market," said Todd Moore, National's strategic audio marketing engineer. "With this single device, designers can replace two mono power amplifiers, a headphone amplifier and load switching circuitry required to switch between headphone and speaker modes, saving cost, board space and design time."

Several features of the LM4863 make it highly desirable for use in portable applications. In the speaker mode, the LM4863 typically delivers 1.5W continuous average power to an 8-ohm speaker bridge tied load (BTL) with 10% typical total harmonic distortion (THD). Using a conventional 1/8-inch stereo connector, the device switches to a single-ended output mode for driving stereo headphones. The LM4863 consumes a minimal 11.5mA of supply current while in the active mode. Only 0.7µA of current is consumed in the power-saving shutdown/mute mode, extending operating time of battery-powered systems. The LM4863 operates on either a 3V or 5V power supply. An internal thermal shutdown mechanism protects the device from overheating, making it virtually indestructible.

Like other recent Boomer audio amplifiers from National, the LM4863 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 16-pin footprint, greatly simplifies overall system design, saves board space and lowers manufacturing costs.

The LM4863 is currently available in either a 16-pin small surface-mount package (SOIC) as the LM4863M or a 16-pin dual in-line package (DIP) as the LM4863N.

National Semiconductor produces analog and mixed-signal based silicon solutions for the information highway, communications, consumer and industrial markets. National Semiconductor is headquartered in Santa Clara, California and has 19,000 employees worldwide. In fiscal 1996, the company reported sales of $2.6 billion.