Products, Materials & Tools | Apr 26, 2010

National Semiconductor: LED Driver with Dynamic Headroom Control for High-Power Applications

National Semiconductor Corp. (NYSE:NSM) today announced the industry’s first LED driver with dynamic headroom control and multiple outputs for high-power applications that accurately and efficiently drives up to four strings of LEDs. The LM3464, a member of National’s PowerWise® energy-efficient product family, maximizes system efficiency and reduces system complexity and cost in LED-intensive applications such as industrial, street and automotive lighting.

Unlike traditional high-brightness LED drivers that drive current to each string independently, the LM3464 LED driver includes four channels to drive up to 20 LEDs per channel, reducing system complexity and cost.

The LM3464’s dynamic headroom control feature dynamically adjusts the LED supply voltage through the power supply feedback to the lowest level required to provide optimal system efficiency.

Technical Features of National’s LM3464 LED Driver:
The LM3464 is a high-voltage current controller with four individual current regulator channels.  It works in conjunction with external N-channel MOSFETs and sense resistors to accurately drive current to each LED string. The LM3464 features a wide input voltage range up to 80V to drive multiple LEDs per string, making the LM3464 ideal for LED-intensive applications.

A thermal foldback feature protects the LEDs from unsafe temperatures that can significantly degrade the light output or lifetime of the LEDs. During an over-temperature condition, the thermal foldback reduces the current through the LEDs until the LED junction temperature of the LEDs returns back to a safe operating temperature.  This user-programmable feature allows for a more robust and reliable thermal design, helping to ensure the lifetime and light output of the LEDs over time and through temperature variances due to environmental conditions of the fixture.

The dynamic headroom control feature monitors the forward voltages of the LED strings and dynamically adjusts the LED supply voltage through the power supply feedback to the lowest level required. By directly controlling the output of the offline regulator, the LM3464 can eliminate the second stage switching regulator commonly required for offline LED power supplies.

The LM3464 features both pulse-width modulation (PWM) and analog dimming interfaces to allow the user to select between various dimming types for different applications. Protection features include VIN under-voltage lock-out, LED open/short circuit and over-temperature fault signaling to the system controller.
Offered in a 28-pin thermally enhanced TSSOP package, the LM3464 is available for design on National’s WEBENCH® LED Designer at http://www.national.com/analog/webench.

For more information or to order samples, visit http://www.national.com/pf/LM/LM3464.html

In Europe, National will demonstrate the LM3464 at euroLED 2010 (Ricoh Arena, Coventry/UK, June 9 – 10, 2010) on its booth LED44.

Pricing and Availability:
National’s LM3464 is priced at $4.50 in 1,000-unit quantities. Samples are available now with production quantities available in June, 2010.  More information about National’s lighting products is available at http://www.national.com/analog/led.

About National Semiconductor:
National Semiconductor is a leader in analog power management technology.  Its products include easy-to-use integrated circuits, PowerWise products that enable more energy-efficient systems, and SolarMagic products which improve the energy output of solar arrays. The company celebrated its 50th anniversary last May.  Headquartered in Santa Clara, Calif., National reported sales of $1.46 billion for fiscal 2009. Additional information is available at www.national.com.

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