National Semiconductor Introduces LED Driver with Dynamic Voltage Adjustment

New PowerWise controller capable of driving two independent dimmable LED strings


September 28, 2010 -- China News -- National Semiconductor Corporation announces the introduction of the LM3942 LED driver with dynamic voltage regulation, which can accurately and efficiently drive both groups Independent dimmable LED light string. The LM3492 driver is part of National's PowerWiseTM line of energy-efficient products that dramatically increase system efficiency, reduce system complexity and system cost for automotive LCD backlight applications.

The LM3492 features dynamic voltage scaling to flexibly adjust the LED supply with the feedback voltage of the boost converter, ensuring the lowest power consumption level and optimizing system efficiency. The driver's built-in three MOSFETs simplify system design complexity and reduce system cost.

National Semiconductor LM3492 LED Driver -- Technical Features

National's LM3492 chipset has a built-in boost converter and dual-channel current regulator that efficiently and cost-effectively drives two independent dimmable LED strings with output power up to 15W and output voltages up to 65V. Due to its extremely high conversion efficiency, the system can achieve ultra-high contrast ratio of 1000:1 with high frequency, narrow pulse width dimming signal. The LM3492 requires only one resistor to set the LED current from 50mA to 200mA.

The Dynamic Voltage Scaling (DHC) feature automatically adjusts the LED drive voltage to a minimum to ensure maximum system efficiency. In addition, although different sizes of displays use different numbers of LEDs to form different backlight groups, as long as the LM3492 chip with dynamic voltage adjustment function can be used, the same driver can be used to drive multiple displays of different sizes, which saves development. Time and reduce the overall cost of the system.

The LM3492 has a multi-function COMM pin that can be used as a bidirectional input/output pin for an external microcontroller (MCU) for command and diagnostic functions.

The LM3492 is available in a more thermally-cooled 20-pin TSSOP package. Engineers can now design with the LM3492 chip in National's WEBENCH? LED Designer design tool, available at http:// Analog/webench.

For further information on the chip or to order samples, please visit http://

Price and availability

The LM3492 is priced at $1.75 each, and the LM3492Q chip that meets the AECQ-100 Level 1 certification (Grade1) is priced at $2.10 each. Both chips are priced at 1,000 units and are available in volume. . For additional information on National Semiconductor's lighting system products, please visit http://

High-resolution photos of these two products are available for download from National's online photo library at http://

National Semiconductor Corporation

National Semiconductor is a leading power management technology developer with a focus on providing easy-to-use analog integrated circuits for the market, and is world-renowned for its supply chain management technology and experience. The company's high-performance analog products increase the energy efficiency of the system and are therefore highly popular with customers. National Semiconductor's corporate headquarters are located in Santa Clara, Calif., with a turnover of $1.42 billion in fiscal year 2010. Additional information about National Semiconductor can be found at

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