National drivers control up to 20 series-connected LEDs

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12764 0 main Date Announced: 29 Jun 2006

National Semiconductor's New Lighting Management Units Drive up to 20 Series-Connected LEDs in Cell Phones, Other Handheld Devices

Duo of Tiny Devices Features High-Voltage Boost Converters, Programmable Constant-Current Drivers

SANTA CLARA, Calif. – National Semiconductor Corporation (NYSE:NSM) today introduced two new, highly integrated lighting management units (LMUs) that include a high-voltage boost converter and programmable constant-current driver to control up to 20 series-connected LEDs in display backlights, and keypad, RGB and camera flash LEDs. The LP3958 and LP5526 LMUs feature tiny micro SMD packages and are well-suited for cell phones and other handheld devices.

National's new LMUs drive from two to five strings of four series-connected LEDs, depending on the lighting application. They are optimized for use in single- or dual-display phones, as well as large display PDA phones. Each features three general-purpose input/outputs (GPIOs) to trigger lighting functions such as Flash or to control additional device-enable signals. The LP3958 features 70 mA of output current for powering display backlight LEDs and the LP5526 features 150 mA of output current for powering display backlight and Flash LEDs. Both devices include an I2C interface.

Technical Features of National's LP3958 and LP5526 LMUs

In single and dual displays, the LP3958 LMU drives up to eight white LEDs grouped as four series-connected LEDs per string, with typically one string per display. Display backlight fade in and fade out is controlled via a two-wire, low-voltage, I2C-compatible interface, allowing easy software implementation. The GPIO functions enable the user to control external devices. The serial interface reduces the wire count through the hinge in flip cell phone designs. For keypads, three series-connected LED strings of up to four LEDs each can be independently controlled to enable light segmentation. This is particularly useful in gaming and navigation applications, for example, in which individual buttons can be selected for illumination. For more information on the LP3958 or to order samples, visit

The LP5526 has the same features and packaging as the LP3958 and can drive multi-die serial-flash LEDs in camera Flash (up to 3W of power) and torch applications. Also, in the case of a software problem, the LP5526 features an internal safety timer to protect Flash LEDs from aging. With the LP5526, the Flash LED output can also be used to drive single or series-connected RGB LEDs. For more information on the LP5526 or to order samples, visit

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

Availability, Packaging and Pricing
The LP3958 and LP5526 are available now in 2.5 mm by 2.5 mm, 25-bump micro SMD packages. The LP3958 is priced at $1.60 each and the LP5526 is priced at $2.00 each in 1,000-unit quantities.

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
National Semiconductor and Webench are registered trademarks of National Semiconductor Corporation.

Gayle Bullock National Semiconductor Public Relations 3689 Kifer Road, M/S G1-124 Santa Clara, CA 95051 Tel: (408) 721-2033 Cell: (408) 464-2516 Fax: (408) 721-3238

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