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National Semiconductor Introduces Two New Flash LED Drivers With Precision Brightness Control For Portable Devices With Cameras

Jun 8, 2006

June 8, 2006 – Worldwide power management technology leader National Semiconductor Corporation (NYSE:NSM) today introduced two new fixed frequency, current mode step-up DC-DC converters.  The LM3551 and LM3552 feature tiny, 14-pin LLP® packages.  Each integrates two NFETs for precision Flash LED brightness control in portable devices with cameras such as mobile phones and PDAs.

The LM3551 and LM3552 DC-DC converters utilize a TORCH/FLASH pin to drive one or more high current Flash LEDs in high power Flash mode or lower power Torch mode.  To prevent LED burnout, the user can choose the value of a capacitor connected to the Flash time out (FTO) pin to program the internal NFETs to turn off after a certain period of time.  To put the device into low power shutdown, an external SD pin on the LM3551 or an EN pin on the LM3552 is available.  During shutdown, the feedback resistors and the load are disconnected from the input to avoid leakage current paths to ground.

Integrated user programmable soft-start circuitry eliminates large in-rush currents at start-up. Over-voltage protection circuitry and a 1.25MHz switching frequency allow for the use of small, low-cost output capacitors with lower voltage ratings.

Key features for the LM3551 and LM3552 include:

  • Up to one amp total drive current   
  • Flash timeout protection   
  • Independent Torch/Flash/Shutdown modes   
  • LED disconnect in shutdown   
  • Programmable soft-start limits in-rush current   
  • Over-voltage protection   
  • Wide voltage range of 2.7V to 5.5V   
  • 1.25 MHz constant switching frequency   
  • Small, low profile, 14-pin non-pullback 4 mm by 4 mm package

For more information or to order samples of the LM3551 and LM3552, visit http://www.national.com/pf/LM/LM3551.html and http://www.national.com/pf/LM/LM3552.html.

About National’s Power Management Products
National Semiconductor is the number one supplier of power management ICs with 14 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 LM3551 and LM3552 are $1.10 each in 1,000-unit quantities.  Lead-free package options are also available.

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 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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