Flat Panel Display Link (FPD-Link) by National Semiconductor is a high-speed interface connecting the output of a video controller in a laptop computer, computer monitor or LCD television set to the display panel. Most laptops, LCD computer monitors and LCD TVs use this interface internally. (Laptops produced before around 1995 and some devices with much lower display resolutions use a TTL or CMOS voltage interfaces instead.) However, DisplayPort is currently in the process of replacing FPD-Link as an internal interface.
FPD-Link uses LVDS, and it was the first large-scale application of the LVDS signaling standard. It uses LVDS on one twisted pair in order to transmit a clock signal, and on the three or more remaining wire pairs it uses LVDS to transmit video data at a bit rate that is seven times the frequency of the clock signal. Since one of those bits indicates whether or not the other six bits transmitted in the clock cycle period needed to be inverted in order to maintain DC balance, each twisted pair other than the clock pair effectively transmits six bits per pair per clock cycle. Since FPD-Link was the first use of LVDS, many display engineers use the terms FPD-Link and LVDS synonymously.
FPD-Link II is a newer version of FPD-Link. The FPD-Link II enhancement embeds the clock signal in the data signal and therefore uses only one differential pair to transmit both the clock and data.
More recently, FPD-Link III embeds bidirectional communications between the source and destination on the one differential pair of FPD-Link II.
Automotive infotainment displays are another application that started using FPD-Link. Now many of the infotainment applications are using FPD-Link II to take advantage of the benefits provided by the embedded clock signal; one being the reduce cable size and weight due to the single wire pair for all the data and the clock.
There is another display interface which uses LVDS: OpenLDI. It is based on FPD-Link, but allows longer cable lengths, and is a rarely used method to connect external display panels to computers. Modern stand-alone LCD display panels for desktop computers use a completely different interface such as DVI.