NATIONAL SEMICONDUCTOR ANNOUNCES INDUSTRY?S HIGHEST EFFICIENCY FRACTIONAL VOLTAGE SWITCHED CAPACITOR CONVERTER

New Device Achieves 95%Efficiency at 50mA for Portable PC and Wireless Power Applications

May 22, 1998 ? National Semiconductor Corporation? today introduced a high-efficiency switched capacitor voltage converter designed for fractional step-up (boost) 3:2 conversion or step-down (buck) 2:3 conversion mode. The LM3351 converts supply voltages at a typical efficiency of 95% at 50mA, prolonging battery life and simplifying the generation of voltages needed for components such as DSPs, microcontrollers, or sub-systems in portable electronic equipment and medical instrumentation. Low switching frequency of 200kHz allows a corresponding low quiescent current of 1.1mA in the step-up mode and 0.8mA in the step-down mode.

?With its size and performance advantage, a low operating current and high operating efficiency, the LM3351 is a leading-edge voltage converter for today?s portable computing and wireless communication market,? said Venkatesh Shan, National's power management marketing director. ?The part?s unique architecture allows designers to simplify their 5V to 3.3V or 3.3V to 5V voltage conversion solutions and displace space-hogging inductor based designs,? he added.

National?s LM3351 drives a 50mA load without the cost, size and radiated EMI related to inductor based switchers, or the power loss of a linear regulator, making it ideal for use in space-constrained portable designs. Housed in a MSOP-8 package, the IC is only 50% the size of the standard SO (small outline) package. The oscillator in the LM3351 has a typical frequency of 200kHz, allowing the use of small, inexpensive capacitors. The LM3351 also includes a low-current shutdown mode that disables the device and reduces the quiescent current to 25nA. A low output impedance of just 4.2 ohms limits the voltage droop to 0.3V at 50mA in step-up mode. An output impedance of 1.8 ohms limits the droop to 0.1V in the step-down mode.

Price and Availability
The LM3351MM (MSOP-8) is priced at $1.19 each in 1000-piece lots and is available now in production quantities. For more information on the LM3351, visit our website at HREF="/pf/LM/LM3351.html">http://www.national.com/pf/LM/LM3351.html, 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 billion and 13,000 employees worldwide. Additional company and product information is available on the World Wide Web at www.national.com.