2010.Sep.10
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Short Introduction to the LVDS Transmission StandardIEEE standard P1596.3-1995 defines Low-Voltage Differential Signals (LVDS) for scalable, coherent interfaces. (SCI) These are a high-speed packet transmission protocol and constitute bus-like transactions like Read and Write. The transactions are targeted at multiprocessor systems communication. In order to reach high data transmission rates, no physical bus is defined. Instead, various fast point-to-point connections are used. LVDS describes rather small differential signals (250…400 mV swing), a data rate of 500 Mbit/s per signal pair and is compatible with CMOS low voltage technologies. Power dissipation is kept at a minimum, because only 2.5 mA are needed to achieve a 250 mV voltage swing at a 100 ohms termination resistor. The transmission medium, for instance cable (twisted pair, BNC, etc) or printed circuit lines, are not specified. If LVDS is used for the transmission of digital LCD signals, first the transceiver signals (graphics controller) are converted from 18…36-bit parallel into several serial data streams. These are then on the receiver side of the link (at the LCD) converted into their original parallel form. Usually, the receiver is already integrated with the LCD. To drive LCD's there are both, single channel and dual channel solutions. Normally the single channel solution is used for displays up to a screen resolution of 1024 x 768 pixels. Higher resolutions are handled with the dual channel solution. Please bear in mind that the mapping of the parallel LCD data to the serial data stream is not standardized! This means that not every LVDS capable LCD module can be used with every LVDS transceiver. However, LVDS gets more and more used today to drive LCD modules so that it is getting easier to find a suitable display on the market. The main advantages of using LVDS are:
LiPPERT products with integrated LVDS transmitters are:
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