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National Semiconductor Introduces Multi-Function White LED Drivers with I2C Compatible Interface for Brightness Control

Aug 9, 2006

August 9, 2006 - National Semiconductor Corporation (NYSE:NSM) today introduced two highly integrated, charge-pump-based, constant current white LED drivers for single or multi-display backlighting in portable consumer products and handsets.  The LM27965 and LM27966 include an I2C compatible interface that allows the design engineer to independently control the brightness on each bank of LEDs.

The LM27965 can drive up to nine LEDs and the LM27966 can drive up to six LEDs in parallel, with a total output current of 180 mA.  Regulated internal current sinks deliver excellent current and brightness matching in all LEDs.  The LED driver current sinks are split into two or three independently controlled groups. The primary group can be configured with four or five LEDs for backlighting a larger main display and the second group (LM27965 only) can be configured with two or three LEDs for backlighting a smaller secondary display.  In addition, an independently controlled LED driver is provided for driving an indicator or general purpose LED.

National’s LM27965 and LM27966 provide excellent efficiency without the use of an inductor by operating the charge pump in a gain of 3/2 or in Pass-Mode.  The proper gain for maintaining current regulation is chosen based on the LED forward voltage so that efficiency is maximized over the input voltage range.

Key features for the LM27965 and LM27966 include:

  • 91 percent peak LED drive efficiency 
  • 25 mm2 total solution size 
  • No inductor required 
  • 0.3 percent current matching 
  • Drives LEDs with up to 30 mA per LED 
  • 180 mA of total drive current 
  • I2C compatible brightness control interface 
  • Adaptive 1× to 3/2× charge pump 
  • Resistor-programmable current settings 
  • External chip RESET# pin 
  • Extended Li-Ion input: 2.7V to 5.5V

Packaging, Pricing and Availability
National’s LM27965 and LM27966 are available now in 24-pin LLP® packages that measure 4 mm by 4 mm by 0.8 mm.  The LM27965 costs $2.20 and the LM27966 costs $1.60 each in quantities of 1,000.  For more information on the LM27965 and LM27966, visit http://www.national.com/pf/LM/LM27965.html
and http://www.national.com/pf/LM/LM27966.html.

About National’s Power Management Products
National Semiconductor is the number one supplier of voltage regulator ICs with 14 percent market share, according to iSuppli’s 2005 Semiconductor Market Share survey.  National's innovative power management products include best-in-class linear regulators; power monitoring, control and reference ICs; and switching converters, such as high-voltage ICs for DC-DC conversion, switched capacitor converters, lighting management ICs and inductive switching converters.  National also offers online tools that enable power designers to select the best power management chips for their applications.  National's Webench® design tool allows designers to choose a product, create and analyze a design, and then build custom prototypes that can be delivered within 24 hours.  More information about National’s power management products is available at http://power.national.com

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 and a variety of broad electronics markets, including medical, automotive, industrial, and test and measurement applications. Headquartered in Santa Clara, Calif., National reported sales of $2.16 billion for fiscal 2006, which ended May 28, 2006.  Additional company and product information is available at www.national.com