National Semiconductor Introduces First 100 V, Fully Integrated Buck Bias Regulator for High-Voltage Systems

National Semiconductor LM5008

April 20, 2004 - National Semiconductor Corporation announced the industry's first 100 V Buck bias regulator, which operates at up to 90 percent power efficiency and delivers significant power savings for customers' designs.

The LM5008 has an integrated 100 V, 500 mA N-Channel power MOSFET and all the functions needed to implement a compact, highly efficient bias power supply. It is the latest addition to National's LM5000 family of high-voltage power solutions and is the company's second generation high-voltage Buck bias regulator. The LM5008 leverages National's latest advanced 100 V analog-BiCMOS-DMOS IC (ABCDXV-2) process technology to extend the voltage range of the popular LM5007 80 V Buck bias regulator, which was introduced last year. It is ideal for use in 48 V power converters, and in telecommunication, automotive and battery-powered applications.

LM5008 (click for larger image)
The LM5008 is used to step down a primary-side distributed voltage bus (up to 100 V input) and produces a low-voltage (12 V typical) bias supply for primary-side control and drive devices. Using the LM5008, a power supply designer can replace a complex, inefficient flyback converter with a simple, efficient Buck regulator. Additionally, as the Buck regulator switches at a higher frequency, filter components are smaller, liberating much-needed board space.

The LM5008's Unique Integration Features

  • Integrated 500 mApk, 100 V VDMOS transistor, ideal for today's high-density and high-efficiency power converters
  • Integrated wide-range 9.5 V to 95 V start-up bias regulator, useful for numerous battery-powered applications
  • Intelligent current limit timers ensure short circuit protection while providing minimum foldback
  • Protective features include integrated over-temperature shutdown and thermal shutdown circuitry

Pricing and Availability
Available today, National's LM5008 is offered in a MSOP-8 package or in a tiny, 4 mm by 4mm 8-pin LLP package and is priced at $1.15 each in 1k volumes. The LM5008 is available for electrical simulation and design optimization on National's WEBENCH® online design tool at

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