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National Semiconductor Introduces Programmable Vcom Calibrator with Non-Volatile Memory For TFT-LCD Displays

Nov 29, 2005

November 29, 2005 – National Semiconductor Corporation (NYSE:NSM) today introduced a programmable Vcom calibrator for thin-film transistor liquid-crystal displays (TFT-LCDs). The LM8342 replaces mechanical potentiometers and eases the labor-intensive Vcom-adjustment process, improving performance, decreasing cost and increasing reliability.

The LM8342 integrates non-volatile memory and a 7-bit digital-to-analog-controlled current source to improve the Vcom calibration procedure. This eliminates the potentiometer adjustment task currently performed using a trimmer adjustment tool and visual inspection. Operators can see a front view of the screen while performing this calibration step, easing manufacturing, especially for large TFT panel sizes.

Key Technical Features
Once the Vcom level has been set, the LM8342 can accurately tune the Vcom voltage by controlling the device’s output current level. This precise Vcom adjustment enables optimal picture quality on the TFT panel. The output current of the LM8342 has temperature stability, yielding a very stable Vcom setting, which minimizes video flicker over the operating temperature range.

The Vcom adjustment through the digital-to-analog (DAC) setting control is handled electronically using the I2C compatible interface. When the operator finds the optimum DAC setting, the data can be stored permanently in the embedded EEPROM (memory) using a simple command. No special external program voltages are required. At any time, the data in the EEPROM can be changed via the I2C compatible interface, allowing manufacturers to easily re-calibrate the display panel.

Enhancing Display Quality
The LM8342 Vcom calibrator expands National’s display portfolio, which provides manufacturers’ products with sharper images, brighter colors and cinema-quality motion video. National offers the industry’s most efficient interface for driving high-definition televisions with more than one billion colors, including LCD, plasma and rear-projection televisions. Its timing controllers combine an LVDS single-pixel input interface with National's RSDS® (reduced swing differential signaling) output driver interface for VGA/SVGA, XGA and Wide XGA resolutions. National’s display products also include power management supplies, audio amplifiers, Gamma buffers and panel repair circuits.

Pricing and Availability
Available in a 10-pin LLP® package, the LM8342 is priced at 76 cents in 1,000-unit quantities. More information, easy-to-order samples and an evaluation board are available at http://www.national.com/pf/LM/LM8342.html
. A large selection of amplifiers is supported by National’s Amplifiers Made SimpleSM, Signal-Path Designer and Active Filter Designer WEBENCH® online design tools.  To explore these solutions, visit http://webench.national.com. To learn more about designing with amplifiers, visit National’s library of online seminars. For more information on National's display portfolio, visit http://www.national.com/appinfo/fpd/.

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, communication 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, California, National reported sales of $1.91 billion for fiscal 2005, which ended May 29, 2005.  Additional company and product information is available at www.national.com
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