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Nov 11, 1996

November 11, 1996 -- National Semiconductor Corporation® today announced the first 3V 65MHz members of its FPD-Link family of host-to-LCD interface devices. Based on LVDS (Low Voltage Differential Signaling) technology, the DS90C383 transmitter and the DS90CF384/CF364 receiver allow portable equipment manufacturers to upgrade to larger LCD screens supporting XGA or SVGA resolution, while at the same time reducing power consumption.

"In order to stay competitive, notebook and portable computer manufacturers are having to offer improved resolution, while extending battery life," said Dave Handorf, Vice President of National's Interface Group. "Before the introduction of the DS90C383 and DS90CF364/CF384 these options were mutually exclusive."

The FPD-Link Family
Members of National's FPD-Link family overcome four barriers that have made it impractical for laptop and notebook computer manufacturers to upgrade to higher screen resolutions. The first barrier is the issue of bandwidth. Increasing resolution on the interface between the computer and the LCD screen pushes the bandwidth considerably. The second barrier is the resulting higher clock rates that generate more electromagnetic interference (EMI).

The third issue is higher addressability requirements which lead to wider cable/connector interfaces, and increased cost. Finally, there's the issue of minimizing power within a system without compromising noise, cost and speed.
To solve these problems, the FPD-Link family uses a combination of LVDS signaling and a clock-splitting technique that allows data serialization. For example, with the DS90C383 and DS90CF384, 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 requires only 10 lines. These reduced lines are one factor that keeps EMI to much lower levels than is possible using conventional TTL or low-voltage TTL interfaces. The specific element that ensures low EMI is the reduced voltage swing and differential nature of LVDS. With less cable lines and the canceling nature of LVDS, the system is able to work efficiently with low EMI.

The DS90C383 and DS90CF364/CF384 are compatible/interoperable with earlier family members and offer laptop and notebook manufacturers a simple migration path to bigger and better screen resolution at a lower voltage. The programmability feature of the DS90C383 enables it to work with either rising edge or falling edge GUI controllers. To save space in the LCD panel, the DS90C383 can be configured to function as an 18-bit color transmitter for use with the DS90CF364 18 bit-color receiver.

"LVDS is ideal for LCD interfacing," said Handorf, "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."

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 rejection. 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). Further, the LVDS CMOS current-mode driver design greatly reduces quiescent power supply requirements.

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

Price and Availability
The DS90C383/CF384MTD and DS90CF364MTD host-to-LCD devices are sampling now and will be in volume production in the first quarter of 1997. The DS90CF364MTD receiver comes in a 48-lead TSSOP package and costs $8.00 each in 1,000-piece quantities. The DS90C383/CF384 drivers and receivers come in a 56-lead TSSOP package and cost $8.25 each in 1,000-piece quantities. For additional information, contact Mitch Abbey at 408-721-4673.

National Semiconductor produces analog and mixed-signal based silicon solutions for the information highway, 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.