Products, Materials + Tools | Jul 26, 2010

National Semiconductor Introduces Industry’s First Common-Anode, Current-Mode, High-Brightness LED Driver with PWM Dimming

National Semiconductor Corporation (NYSE:NSM) today introduced the industry’s first common-anode, current-mode, high-brightness light-emitting diode (LED) driver with pulse-width modulation (PWM) dimming. The LM3433, a member of National’s PowerWise® energy-efficient product family, drives high-power, high-brightness LEDs in backlighting, projector and solid-state lighting applications.

National will show its LM3433 LED driver with Luminus Devices’ PhlatLight™ LED in National’s booth #26 at the LEDs 2007 conference in San Diego from Oct. 24 to 27.  On Oct. 26 at the same conference, Luminus Devices will demonstrate its LED and National’s driver at 2:45 p.m during session six, “Entertaining in a New Light”.

National’s LM3433 LED driver opens the way for high-reliability LEDs to be used in large-screen liquid crystal display (LCD) television (TV) backlighting applications where a common anode approach offers a thermal advantage.  In another example, LEDs can be used in today’s shrinking “pocket projector” designs for a wider color gamut, higher reliability and longer life expectancy than the ultra-high performance (UHP) lamps used today.

Luminus’ PhlatLight LEDs are a new class of LED for very high-brightness applications where a point source of light is needed.  The PhlatLight RGB LED demonstration at National’s booth will be capable of producing over 3,000 white lumens.  “PhlatLight LEDs are being designed into a number of display and lighting applications,” said John Langevin, vice president of sales and marketing at Luminus.  “National’s LM3433 driver provides a more complete solution for our customers, enabling use at the intended high performance levels that the PhlatLight chipsets were designed for.”

Technical Features of National’s LM3433 LED Driver:
National’s LM3433 is a constant on-time DC-DC buck (step-down) constant-current regulator.  It outputs a negative constant current for lighting high-power, high-brightness LEDs.  The negative voltage option allows the anode of the LED to be tied directly to the ground-referenced chassis for maximum heat sink efficacy.  The short constant-on-time architecture allows the use of small external passive components and no output capacitor.  Two current control modes modulate LED brightness.  An analog current control input is provided so the LM3433 can be adjusted to compensate for LED manufacturing variations.  The other current control is a logic-level dimming input for PWM control of LED brightness.  The PWM functions by shorting out the LED with a parallel switch, allowing high PWM dimming frequencies up to 40 KHz.  Additional features include thermal shutdown, VCC under-voltage lockout and logic-level shutdown mode.

The LM3433 is offered in a 24-pin LLP® package.  For more information on the LM3433 or to order samples, visit .

About National’s Power Management Products:
National solves power management design problems in space- and energy-constrained applications from feature-rich handheld devices through large line-powered systems. From the novice power designer to the power expert, National’s products, people and design tools enable customers to design green-powered systems with complex power supplies in the shortest amount of time. High-performance products include switching regulators such as National’s flagship SIMPLE SWITCHER® family, and application-specific products including white-LED drivers and Power-over-Ethernet controllers. More information about National’s power management products is available at .

Availability and Pricing:
Available now, the LM3433 is priced at $2.25 each in 1,000-unit quantities.

About National’s PowerWise Brand:
National’s PowerWise brand reflects the company’s energy-efficient product portfolio.  It signifies products with outstanding performance-to-power at the component level, as well as products that provide an outstanding, energy-efficient solution when coupled with other National parts.  National’s PowerWise family of products features energy-efficient power management, operational amplifiers, interface and data conversion products.  For more information about National’s PowerWise brand, visit: .

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, interface products and data conversion solutions. National's key analog markets include wireless handsets, displays, communications infrastructure, medical, automotive, industrial, and test and measurement applications. Headquartered in Santa Clara, Calif., National reported sales of $1.93 billion for fiscal 2007, which ended May 27, 2007. Additional company and product information is available at .