NATIONAL SEMICONDUCTOR ADDS FIRST 5A STEP-DOWN DC/DC CONVERTERS TO SIMPLE SWITCHER? FAMILY

New Offering Combines Advantages of High Efficiency (>90%) and High Frequency (260kHz) for Compact High-Current Designs

July 7, 1998 - National Semiconductor Corporation? today announced the addition of four high-current, high-efficiency step-down power converters to its popular Simple Switcher? line. Two of the new devices, the LM2678 and LM2679, are the first Simple Switcher buck converters rated at 5A output with only PCB traces used as a heat sink. The other two buck converters, LM2673 and LM2676, are rated at 3A output.

All four members of the LM267X series feature efficiency ratings greater than 90%, making them ideal for high-current applications. The devices' high switching frequency (260KHz) enables designers to build a power supply with just five low-profile surface-mount components. Voltage options include 3.3V, 5V, 12V and adjustable. The LM2678 and LM2679 offer special features, including adjustable current limits and a soft-start capability that prevents excessive in-rush current and reduces transient voltage surges. Both new ICs also offer external shutdown and self-protection features such as over-temperature shutdown.

"Continuing with the simplicity and guaranteed performance theme of previous generations, the newest series of switchers has been developed with high current output as well as high efficiency," said Venkatesh Shan, National's director of marketing for power management products. "The unique, easy-to-use Simple Switcher concept now extends to a range of designs with outputs from 0.5A to 5A and encompasses an expanded group of applications."

National Guarantees Switchers-Made-Simple® Circuit Performance
A popular feature of National's Simple Switcher line is its new Windows-compatible Switchers-Made-Simple design software, version 5.0. The software provides customers with a complete circuit-design solution including schematics, component lists and vendor information. Use of standard inductors or transformers available from National's magnetics partners precludes the need for any magnetics design. National guarantees system performance for DC/DC converter applications designed using the components listed in either the company's design software or data sheets.

The LM2673/6/8/9 are available in the popular TO-263 or TO-220 7-pin packages. The devices offer the same ease of use that has made Simple Switcher ICs the most widely accepted category of DC/DC converters available.

Price and Availability
Pricing in 1000-lot units for the LM2673 is $3.50 for both the S-Version (TO-263 package) and the T-Version (TO-220). The LM2676S and T are priced at $3.35; the LM2678 S- and T-versions are $3.55 and the LM2679S and T are $3.70. All four devices are available in production quantities.

For more information on the Simple Switcher family, visit our website at http://www.national.com/appinfo/power/, or contact National's Customer Response Group at 1-800-272-9959.

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.

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