Editorial Contact
Gerry Ziegler
National Semiconductor
(408) 721-8665
gerry.ziegler@nsc.com

Reader Information
Design Support Group
(800) 272-9959
World Wide Web
www.national.com

NATIONAL SEMICONDUCTOR EXPANDS ITS FAMILY OF POWER SWITCH AND PROTECTION ICS FOR THE GROWING USB-ENABLED DESKTOP PC MARKET

September 25, 2000 - National Semiconductor Corporation (NYSE:NSM) today expanded its offering of power switches and over-current protection devices with new triple and quad-port switches for the burgeoning USB market. Dataquest predicts USB peripheral revenue will grow at a rate of 151% between 1999 and 2003.

Like other members of National?s USB switch and protection IC family, the LM3543 triple-port and LM3544 quad-port switches perform two vital tasks for USB downstream ports. In addition to switching power to a USB "tree" of peripheral devices, they also notify their controllers when over-current, over-temperature or under-voltage fault conditions are detected. Such protection is required for devices that source power to computer peripherals, including root hubs, monitor and other embedded hubs, and stand-alone hub devices.

"With the success of Win98 and arrival of Windows 2000, we?ve seen a corresponding growth in sales and availability of USB peripherals," said Venkatesh Shan, Power Management marketing director for National. "Notebook PC makers and hub manufacturers have historically relied on silicon switches for both over-current protection and control of power to the bus. But many desktop PC makers have resorted to PTC (positive temperature coefficient) fuses for over-current protection to the exclusion of the power switching. Now, with the growth of multiple port hubs and a competitive cost structure of silicon-based switches, desktop PC suppliers are taking a new look at combining switching and protection on a single chip. Since five desktop PCs are sold for every notebook, that represents a significant new market."

A 7ms internal delay for the error flag pin stops erroneous over-current reporting caused by inrush currents during hot-plug events. It also saves cost by eliminating an RC filter with its two external components per port. The LM3543/44 provides thermal isolation between ports in over-current conditions, preventing good ports from glitching or asserting the error flag pin unnecessarily. In direct short conditions, a thermal shutdown protection feature safeguards the device. With a low RDS(on) rated at 90 milliohms, worst case, the device helps assure a minimum supply voltage to the ports, wider tolerance on the power supply, and fewer constraints on PCB layout.

Pricing and Availability
Available now in the SO-16 package that conforms to industry standard pinout, the LM3543M is priced at $1.60 in quantities of 1,000 and LM3544 is priced at $1.80 per 1,000. For more information on these products, visit National's World Wide Web site at www.national.com/pf/LM/LM3543.html and www.national.com/pf/LM/LM3544.html, or contact National's Design Support Group at 1-800-272-9959.

About National Semiconductor
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, California, National reported sales of $2.1 billion for its last fiscal year and has about 10,500 employees worldwide. Additional company and product information is available on the World Wide Web at www.national.com.