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National Semiconductor Adds Flexibility and Higher Performance to SIMPLE SWITCHER Buck Switching Regulator Family

Six New Products Featuring Patented Emulated-Current-Mode Technology Enable Power Supply Designers to Quickly "Dial in" Performance

Jan 30, 2007

January 30, 2007 - Worldwide power management leader National Semiconductor Corporation (NYSE:NSM) today announced the addition of six high-frequency buck regulators to its popular SIMPLE SWITCHER® product family along with a “dial-in” performance enhancement to its WEBENCH® design environment.  The six new regulators feature a unique combination of high performance, flexibility and ease-of-use for DC-DC power supply designs.

National’s new buck regulators and enhanced WEBENCH suite of tools enable novice as well as seasoned power supply designers to easily “dial-in” their size and efficiency requirements while also realizing fast time to market.  Design results are verified by WEBENCH online electrical and thermal simulations and created for 24-48 hour delivery using the BuildIt!™ custom prototype power supply kit.

The new regulators operate with an input voltage range up to 75V and deliver up to 3A of continuous output current.  The patented emulated-current-mode technology provides superior load transient response in low duty cycle applications that are not addressable by traditional current mode control.  Operating frequency is adjustable from 50 kHz to 1 MHz, providing industry-leading dynamic range.  To reduce EMI, a frequency synchronization pin allows multiple ICs from the family to self-synchronize or to synchronize to an external clock.  The new regulators guarantee robustness with cycle-by-cycle current limit, short-circuit protection and thermal shut-down.

“Combined with National’s WEBENCH suite of tools, SIMPLE SWITCHER regulators allow design engineers to make decisions about their power supply design, such as the trade-off between size and efficiency,“ said Mal Humphrey, product line director for National’s Power Management Group.  “Any engineer, including seasoned power supply designers, can create, optimize and analyze their design in just one minute.

About Emulated-Current-Mode Technology
Emulated-current-mode control overcomes traditional current-mode control’s noise susceptibility by emulating the buck switch current signal, which is then used for current-mode control.  The emulated buck switch current signal is the sum of an emulation ramp current and the sampled diode current just before switching occurs.  Avoiding direct buck switch current measurement minimizes the effect of switching noise, while maintaining the benefits of the current-mode control.

Technical Features of the New SIMPLE SWITCHER Buck Switching Regulators
Six products are included in the new line of SIMPLE SWITCHER regulators.  The 0.5A LM5574, 1.5A LM5575 and 3.0A LM5576 buck regulators feature a very wide input voltage range from 6V to 75V and adjustable switching frequency between 50 kHz and 500 kHz.  The 0.5A LM25574, 1.5A LM25575 and 3.0A LM25576 buck regulators feature wide input voltage range from 6V to 42V and adjustable switching frequency between 50kHz and 1MHz. 

Offered in a 16-pin TSSOP, the LM5574 integrates a 75V, 750 milli-Ohm, N-channel MOSFET and the LM25574 integrates a 42V, N-channel MOSFET.  For more information on the LM5574 and LM25574 or to order samples and an evaluation board, visit http://www.national.com/pf/LM/LM5574.html and http://www.national.com/pf/LM/LM25574.html

Offered in a 16-pin TSSOP package with exposed pad, the LM5575 integrates a 75V, 330 milli-Ohm, N-channel MOSFET and the LM25575 integrates a 42V, N-channel MOSFET.  For more information on the LM5575 and LM25575 or to order samples and an evaluation board, visit http://www.national.com/pf/LM/LM5575.html and http://www.national.com/pf/LM/LM25575.html

Offered in a 20-pin TSSOP package with exposed pad, the LM5576 integrates a 75V, 170 milli-Ohm, N-channel MOSFET and the LM25576 integrates a 42V, N-channel MOSFET.  For more information on the LM5576 and LM25576 or to order samples and an evaluation board, visit http://www.national.com/pf/LM/LM5576.html and http://www.national.com/pf/LM/LM25576.html

All of the new SIMPLE SWITCHER regulators are available for simulation on National’s WEBENCH design tool.  For more information, visit http://switcher.national.com.

About National’s SIMPLE SWITCHER Regulator Family
Introduced in 1989, National today offers an extensive portfolio of more than 500 SIMPLE SWITCHER products with a variety of feature-set, package, voltage and current options.  All are quick and easy to design with using National’s online WEBENCH power supply design tools.  WEBENCH design tools include software that provides customers with a complete solution including passive component selection, electrical schematics, component lists, optimized circuit performance and more.  National's online design environment, complemented by National’s evaluation boards, provides a complete suite of tools that has made the SIMPLE SWITCHER family the most widely accepted DC-DC converters.  Since system power supply needs are often not defined until late in a project, the SIMPLE SWITCHER solution can be the key to getting products to market quickly and reliably.

About National’s Power Management Products 
National Semiconductor is the number one supplier of voltage regulator ICs with 14 percent market share, according to iSuppli’s 2005 Semiconductor Market Share survey.  National's innovative power management products include best-in-class linear regulators; power monitoring, control and reference ICs; and switching converters, such as high-voltage ICs for DC-DC conversion, switched capacitor converters, lighting management ICs and inductive switching converters.  National also offers online tools that enable power designers to select the best power management chips for their applications.  National's WEBENCH design tool allows designers to choose a product, create and analyze a design, and then build custom prototypes that can be delivered within 24 hours.  More information about National’s power management products is available at

Pricing and Availability
National’s six new SIMPLE SWITCHER regulators are available now.  Prices for the products range from $1.35 to $2.90 in 1,000-unit quantities.

Note to editors:  To view high-resolution downloadable photos of these products, visit National's photo gallery at http://www.national.com/company/pressroom/gallery/power.html.

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