National Semiconductor Launches DHC-Supported LED Driver for Automotive LCD Backlight Applications

PowerWise controller driving two independently dimmable LED strings

– National Semiconductor Korea (CEO: Choi Chung-won) today introduced the new LM3492 LED driver, which supports DHC (Dynamic Headroom Control). DHC serves to accurately and efficiently deliver current to two independently dimmable LED strings. The LM3492 is part of National’s PowerWise® energy-efficient product family and offers the advantage of maximizing system efficiency in automotive LCD backlight applications while reducing system complexity and costs.
The LM3492's DHC is characterized by dynamically adjusting the LED supply voltage required to provide optimal system efficiency, ranging from boost converter feedback to the lowest power level. Three embedded MOSFETs reduce system complexity and cost.

Technical Features of the National LM3492 LED Driver
Integrating a boost converter and a 2-channel current regulator, the National LM3492 drives two independently dimmable LED strings with a maximum power of 15W and a maximum output voltage of 65V in an efficient and economical manner. With the integrated fast slew-rate current regulator, a high contrast ratio of 1000:1 can be achieved with high-frequency and narrow pulse-width dimming signals. LED current can be programmed from 50 mA to 200 mA using a single resistor.
To maximize efficiency, DHC (Dynamic Headroom Control) automatically adjusts the voltage-driven LEDs to the lowest level. DHC also has the advantage of saving overall development time and costs by allowing the use of a single BOM when the number of LEDs in the string required for backlight panels of different sizes differs.
The LM3492 has bidirectional input/output pins that serve to provide command and diagnostic functions through communication with an external MCU.