New Industry Products

National Semi Introduces LED Driver with Dynamic Headroom Control for High-Power Applications

April 25, 2010 by Jeff Shepard

National Semiconductor Corp. announced what it says is 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® product family, is said to maximize system efficiency and reduce system complexity and cost in LED-intensive applications such as industrial, street and automotive lighting.

According to the company, 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.

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 well suited 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.

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.

National’s LM3464 is priced at $4.50 in 1,000-unit quantities. Samples are available now with production quantities available in June, 2010.