NATIONAL SEMICONDUCTOR INTRODUCES 1.5A SYNCHRONOUS SWITCHING REGULATOR IN TSSOP-16

LM2653 Regulator Offers 97% Efficiency in a Tiny Form Factor to Meet the Power Requirements of Notebook Computers and Other Portable Products

April 26, 1999 - National Semiconductor Corporation? (NYSE: NSM) today announced the LM2653, a high-efficiency switching regulator that provides portable system designers with an efficient, space-saving solution for a wide range of system power needs. With its low RDS(ON), the LM2653 offers 1.5A output in a tiny, self-contained TSSOP-16 package, making it an ideal power management solution for space-constrained portable devices that require high efficiency and high output current in a small package.

"The LM2653 expands National's comprehensive power management product offerings that address the needs of the portable market," said Sonia Ramirez, product manager for National's power management product line. "As this market continues to grow, National's process technologies will enable us to offer products like the LM2653 that provide the power, size and efficiency required by a range of portable designs."

The LM2653 comes in the TSSOP package that measures just 5.0mm (length) by 4.4mm (width) by 1.1mm (height), and is much thinner than similar product offerings, making it ideal for notebook computer designs that typically measure less than one inch in height. A 300kHz fixed-frequency internal oscillator allows for the use of extremely low-profile components. The regulator is also self-contained, integrating power, control and drive functions on the IC and allowing for simpler system design.

The LM2653 provides 1.5A output, the highest available in a TSSOP package, as well as efficient power conversion over a 100:1 load ratio (1.5A to 15mA). The device also includes a number of power-saving features to maximize efficiency. To conserve battery life, for instance, the regulator enters a low-power hysteretic mode during light loads to keep efficiency high. It also uses synchronous rectification to achieve 97 percent efficiency.

The LM2653 generates an adjustable output as low as 1.5V from an input voltage range of 4V to 12V, enabling it to step down from a wide input range to a lower range to provide a variety of system voltages, including those of CPU I/O, video and memory chips. The LM2653 complements other National power management products that provide CPU-core power and the main 5V and 3.3V supplies. In combination, they provide a complete power supply solution for notebook computers and other portable products.

To protect the circuitry of notebook computers, the LM2653 also features a number of protection features, including thermal shutdown, input undervoltage lockout, adjustable soft-start, cycle by cycle current limit, and output overvoltage and undervoltage protection.

Price and Availability
The LM2653 is priced at $3.15 in quantities of 1000. It will be available in production quantities in April 1999. For more information on the LM2653, visit National's web site at http://www.national.com/pf/LM/LM2653.html.

National Semiconductor provides system-on-a-chip solutions for the information age. Combining real-world analog and state-of the-art digital technology, the company's chips lead many sectors of the personal computer, communications and consumer markets. With headquarters in Santa Clara, Calif., National has annual sales of more than $2 billion and 11,500 employees worldwide. Additional company and product information is available on the World Wide Web at www.national.com.