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National Semiconductor Introduces Industry’s First Synchronous Switching Controller in SOT-23 Package

LM1770’s Constant On-Time Topology Eliminates Need for Compensation Components, Making it Easy to Implement this High-efficiency Switching Controller

Sep 27, 2005

September 27, 2005 - National Semiconductor Corporation (NYSE: NSM) today introduced the industry’s first SOT-23 synchronous buck switching controller, the LM1770.  This efficient controller utilizes constant on-time control, making it easy to employ because it does not require external compensation.

The LM1770, packaged in the tiny SOT23-5, provides low-voltage point-of-load regulation from standard 5V and 3.3V rails in space-constrained applications such as set-top boxes, cable modems, digital video recorders and printers.  This versatile solution also replaces switching regulators and LDOs in enterprise server and point-of-sale applications where efficiency is crucial.

“With the LM1770, National Semiconductor continues to set the standard in power management with products that offer benchmark performance and are easy to use, accelerating the customer’s time-to-market,” said Paul Greenland, director of strategic marketing for National Semiconductor’s Power Management Group.  “The LM1770 allows designers to solve point-of-load regulation issues with a small-footprint solution which reduces power consumption and eliminates compensation components.”

About the LM1770
The LM1770 is a synchronous buck switching controller for low-voltage DC-DC conversion.  Features and benefits of the LM1770 include:

  • Constant on-time control:  Easy-to-use topology that requires no external compensation       
  • Synchronous operation:  High-side PFET and low-side NFET enable higher efficiency, resulting in reduced power dissipation       
  • Fast transient response:  Allows for fewer or smaller filter capacitors       
  • Input voltage range of 2.8V to 5.5V:  Ideal for point-of-load regulation from a 3.3V or 5V rail       
  • Output voltage as low as 0.8V: Supports applications requiring less than 1V power rails       
  • Internal soft-start:  Limits in-rush current and allows for a controlled start-up       
  • Short circuit protection:  Prevents damage to the application       
  • Three on-time options:  Allow for selection of operating frequency range       
  • Small SOT23-5 package:  Ideal for space-constrained applications

About National’s Power Management Products
National Semiconductor is the number one supplier of power management ICs with 14.1 percent market share, according to iSuppli’s 2005 voltage regulator/reference survey.  National’s power management revenue grew 37.3 percent in 2004 over the previous year, compared to 24 percent growth for the industry.  National's innovative power management products include best-in-class linear regulators; power monitoring, control and reference ICs; and switching converters, such as high-voltage ICs for DC-DC conversion, switched capacitor converters, lighting management ICs and inductive switching converters.  National also offers online tools that enable power designers to select the best power management chips for their applications.  National's Webench® design tool allows designers to choose a product, create and analyze a design, and then build custom prototypes that can be delivered within 24 hours.  More information about National’s power management products is available at http://power.national.com
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Pricing and Availability
Available now, the LM1770 is priced at 95 cents in 1,000-unit quantities.  For more information about the LM1770, including how to order samples and evaluation boards, please visit http://www.national.com/pf/LM/LM1770.html
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Note to Editors:  To view a high-resolution downloadable photo of this product, visit National's photo gallery.

About National Semiconductor
National Semiconductor, the industry's premier analog company, creates high-value analog devices and subsystems.  National's leading-edge products include power management circuits, display drivers, audio and operational amplifiers, communication interface products and data conversion solutions.  National's key analog markets include wireless handsets, displays and a variety of broad electronics markets, including medical, automotive, industrial, and test and measurement applications.  Headquartered in Santa Clara, California, National reported sales of $1.91 billion for fiscal 2005, which ended May 29, 2005.  Additional company and product information is available at www.national.com
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