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Oct 7, 1996

October 7, 1996 -- Enabling the move by notebook computer manufacturers to bigger and higher resolution LCD screens, National Semiconductor Corporation® today announced the availability of the market's first 5V 65MHz LVDS host-to-LCD interface devices. The DS90CF564 and DS90CF583/4 are the newest members of National's FPD-Link family and offer portable computer manufacturers an easy way to connect VGA, SVGA or XGA displays without increased cost.

The DS90CF564 and DS90CF583/4 overcome three barriers that have made it impractical for laptop and notebook computer manufacturers to upgrade to higher screen resolutions. First, increasing resolution pushes up the bandwidth on the interface between the computer and the LCD screen by the square of the number of pixels. Second, the resulting higher clock rates generate more electromagnetic interference (EMI). Finally, the higher addressability requirements lead to wider cable/connector interfaces, which are not cost effective.

To solve these problems, the DS90CF564 and DS90CF583/4 use a combination of LVDS (low voltage differential signaling) and a clock-splitting technique that allows data serialization. As a result, the interface to a 1024x768 XGA LCD with 24-bit color requires only 10 lines (instead of the customary 52) to achieve the necessary bandwidth. An SVGA interface with 24 bit color also only requires 10 lines. Fewer lines along with the reduced swings and differential nature of LVDS reduces EMI to much lower levels than is possible using conventional TTL or low-voltage TTL interfaces. The DS90CF564 and DS90CF583/4 support all types of LCD-based products, from PCs to industrial and telecommunications equipment.

"LVDS is ideal for LCD interfacing," said Mitchell Abbey, Interface product marketing manager at National Semiconductor. "Its ability to move data at phenomenal rates without high EMI or high power dissipation gives laptop and notebook computer makers an easy way to give customers what they want; better screen resolutions. The first members of the FPD-Link family, the DS90CF561/2 and DS90CF581/2, gained quick acceptance with design wins at leading computer and flat panel display manufacturers. We see the DS90CF564 and DS90CF583/4 building on that success by offering an easy transition to single chip, 65MHz performance."

LVDS Technology
The key to LVDS technology is the use of a differential data-transmission scheme. Instead of designating a precise voltage level for a logic one or zero, the LVDS standard specifies a voltage differential. This approach ensures outstanding common-mode-noise immunity. Any noise introduced into the medium is seen by receivers as common-mode modulations and is rejected. The receivers respond only to differential voltages.

To achieve high data rates and keep power requirements low, LVDS uses a differential voltage swing of only 345 mV(typ). Furthermore, the LVDS CMOS current-mode driver design greatly reduces quiescent power supply requirements.

National's LVDS devices implement TIA/EIA-644 (Telecommunications Industry Association/Electronic Industries Association) LVDS standards, the IEEE (Institute for Electrical and Electronics Engineering) and 1596.3 SCI (Scaleable Coherent Interface) LVDS standard.

Price and Availability:
The DS90CF564 and DS90CF583/4 host-to-LCD devices will be sampling early in the fourth quarter with full production by year-end. The DS90CF564MTD receiver comes in a low-profile 48-lead TSSOP package and costs $7.00 each in 1,000-piece quantities. The DS90CF583/4MTD drivers and receivers cost $7.25 each in 1,000-piece quantities and come in the low-profile 56-lead TSSOP packages.

National Semiconductor® produces analog and mixed-signal-based silicon solutions for the information superhighway, communications, consumer and industrial markets. National Semiconductor is headquartered in Santa Clara, California and has 19,000 employees worldwide. In fiscal 1996, the company reported sales of $2.6 billion. Additional company information is available on the World Wide Web at www.national.com.