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National Semiconductor Delivers Industry’s Most Powerful Ceramic Speaker Driver

Device Enables Best-in Class Audio Quality for Ultra-Thin, Feature-Rich Handsets

May 29, 2007

May 29, 2007 - National Semiconductor Corporation (NYSE:NSM) today introduced a single-chip Boomer® audio power amplifier that delivers the industry’s highest voltage for driving ceramic speakers used in a wide range of 3V portable devices. Driving the ceramic speaker at higher voltages allows it to produce a higher sound-pressure level (SPL) for applications that require louder sound. The LM48555 drives ceramic speakers in cell phones, smartphones, notebook computers and other small handheld devices.

With a ceramic speaker load equivalent to 1 uF + 20-Ohms, the LM48555 provides a voltage drive of 15.7V peak-to-peak with less than 1 percent total harmonic distortion plus noise (THD+N). In addition, the LM48555’s tiny 12-bump micro SMD package has a footprint of 1.5 mm by 2.0 mm, making it possible for manufacturers to create ultra-thin, feature-rich handsets.

Ceramic speakers require higher voltage, but less current compared to traditional moving coil speakers. The primary benefits of ceramic speakers are their thin profile and light weight. Voice coil speakers are typically 4 mm or more in thickness, while ceramic speakers are only 0.7 mm thick and often weigh less than one gram. More information on these speaker types is available in National’s Audio Education Series eBooks at audio.national.com.

Key Features – LM48555 Boomer Audio Power Amplifier
The LM48555 delivers 15.7V peak-to-peak from a 3V DC power supply, and typically offers low quiescent current of 7.5 mA from a 5V supply. The LM48555 can achieve additional battery savings with its low power shutdown mode, and its differential inputs improve noise rejection. Power supply rejection ratio (PSRR) is typically 80 dB at 217 Hz. The LM48555 does not require bootstrap capacitors or snubber circuits. The amplifier’s advanced “pop-and-click” circuitry eliminates noise that typically occurs during turn-on and turn-off transitions. The LM48555’s integrated boost regulator features a soft start function that minimizes transient current during power-up.

Pricing and Availability
The LM48555, available in a 12-bump thin micro SMD package, is priced at $1.95 each in 1,000-unit quantities. More information and easy-to-order samples are available at http://www.national.com/pf/LM/LM48555.html
. National’s WEBENCH® online design tool supports a large selection of audio amplifiers. 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 and audio design tutorial eBooks at audio.national.com.

Note to editors: To view a high-resolution downloadable photo of the new product, visit National's photo gallery.

About National’s Audio Portfolio
National Semiconductor has been a leading provider of audio solutions for more than 30 years and offers a wide range of products in its Boomer®, Overture® and high-performance audio lines. National works with every major handset maker in the world and is the leading provider of analog audio solutions for the cell phone market. The company's line of Boomer audio amplifiers and subsystems enhance and enrich the entire range of sound – from voice, ring sounds and music – that can be amplified in mobile phones and other portable equipment.  National manufactures Class AB and Class D speaker amplifiers, headphone amplifiers and audio subsystems for many applications ranging from portable devices to high-power, high-fidelity audio systems. The company offers its higher-power Overture amplifiers for mid-performance consumer applications, and National’s new high-performance series brings dramatically improved sound quality to high-fidelity consumer and professional audio equipment. For more information on National’s audio products, visit

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, 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, Calif., National reported sales of $2.16 billion for fiscal 2006, which ended May 28, 2006.  Additional company and product information is available at www.national.com