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National Semiconductor's New Regulator Controller Provides Low Output Voltage, High Efficiency for PCs and Notebooks

Jun 9, 2003

June 9, 2003 - Providing versatile power management solutions for the computing market, National Semiconductor Corporation (NYSE: NSM) today announced a highly integrated regulator controller that offers a complete power supply for a microprocessor, FPGA or DSP-based system.  National's new dual synchronous buck (step-down) controller has two outputs that can power notebook and desktop computers, networking equipment, set-top boxes, graphics cards including DDR memory, and industrial computer boards.

National's LM2647 is an adjustable 200-500 kHz dual channel voltage-mode controlled high-speed synchronous buck regulator controller designed for battery-powered applications such as laptop and notebook computers.  The device's voltage mode control with input feed-forward and extremely low minimum ON-times allows for higher operating frequencies and smaller inductors particularly in low-output voltage, high-input voltage applications, ensuring excellent transient response.

"The LM2647 drives N-channel MOSFETs which keeps the bill of materials cost down without sacrificing efficiency," said Paul Greenland, marketing director of National Semiconductor's Power Management Group.  "The optimal combination of small filter components, a sub 1 V output and small footprint makes the LM2647 a very attractive, power and space-efficient solution."

The LM2647 is ideal for efficient buck regulators with output voltages down to 0.6 V.  It has an input voltage range of 5.5 V to 28 V, an adjustable switching frequency of 200 to 500 kHz and has 1.5 percent overall reference voltage accuracy. Low-side MOSFET current sensing combined with adaptive duty cycle clamping dramatically reduces over-current stress under abnormal loading conditions.  This gives higher field reliability, even with smaller MOSFETs and inductors.  The LM2647 also features a user-selectable pulse-skip mode that improves efficiency at light loads by reducing MOSFET switching and drive power losses.
The two independently programmable outputs switch 180° out of phase. This interleaved switching reduces the size of the input capacitor and filter.  Small filter inductors at the input and output permit faster transient response and reduce voltage transients at load application and release. The LM2647 provides sequencing (UVLO, Enable), protection (Soft Start, UVP/OVP) and signaling (Power Good) features that make the device a robust and predictable power management solution.
National has developed leading power management technology for a wide range of applications including communication infrastructure, wireless handsets, other portable devices, servers and PCs.  For innovative power solutions from National, visit:

Availability, Pricing and Packaging
Available now in 28-lead TSSOP and 28-lead LLP packages, National Semiconductor's LM2647 is priced at $2.60 each in quantities of 1,000 units.

About National Semiconductor
National Semiconductor is the premier analog company driving the information age.  Combining real-world analog and state-of-the-art digital technology, the company is focused on analog-based semiconductor products, which include stand-alone devices and subsystems in the areas of power management, imaging, display drivers, audio, amplifiers and data conversion.  The company targets key markets such as wireless, displays, information infrastructure and a broad range of portable applications.  With headquarters in Santa Clara, California, National reported sales of $1.5 billion for its most recent fiscal year.  Additional company and product information is available on the World Wide Web at www.national.com