LVDS and Panel Link

Industrial end users, system designers and the Consumer market in general are focused on LVDS and PanelLink standards and the benefits they can provide. These standards have already been applied to many Advantech products such as Advantech's PCM-5820, PCM-5864, POS-562 and the PCM-9570 (optional). These models demonstrate how digital panel interfaces can have a dramatic affect on the data exchange capability and distance allowed between PC board and FPD display panels. Both these standards are electrical interfaces that can quickly transfer a large amount of data over long cable lengths, i.e. from a Graphics card to a display panel.

LVDS Characteristics

When you mention the impressive data rate of 400 Mbps at 15 meters for LVDS, you immediately realize how significant the differences are between analog and digital interfaces. There are several other factors other than significantly increased data transfer rate and image quality that make LVDS (Low-Voltage Differential Signaling) very attractive to industrial users. One is that LVDS drivers and receivers maintain excellent signal levels and performance while operating on supply voltages as low as 2 V. This low voltage allows LVDSs to operate independently from the main power supply voltage. Another factor is that LVDS drivers and receivers have a low swing voltage. This voltage is typically around 345 mV. This allows LVDS devices to achieve high speeds while using relatively little power. This low differential swing voltage together with self-canceling EMI, reduces EMI problems significantly. This is especially important in space-critical applications. This is also why LVDS has already been widely used in Notebook computer panel connections.

PanelLink Digital Panel Interface Technology

PanelLink technology was developed by Silicon Image of Cupertino, California. They provide transmitter and receiver chips that transfer data using TMDS (Transition Minimized Differential Signaling) which is a standard backed by VESA (Video Electronics Standards Association) for both its Flat Panel Display-2 standard for notebook computers and its Plug and Display standard for the desktop monitor digital interface.PanelLink proponents suggest that the PanelLink solution is simpler in that their connection depends on fewer pairs of wires than the LVDS connection. PanelLink connections can also be run over standard twisted pairs over distances up to ten meters. One important note is that the Digital Flat Panel (DFP) Working Group and the Digital Display Working Group (DDWG) have chosen TMDS and PanelLink as their Digital Visual Interface (DVI) standard. DDWG is an industry cooperative led by Silicon Image, Intel, Compaq, Fujitsu, Hewlett-Packard, IBM and NEC.

All-Digital FPD Interface Requirements

No matter which digital standard an end user uses for their industrial applications, it will have to provide the following criteria. Be compatible so that system and display products from different suppliers can be made available in an open market. Become a standard for the electronics and PC industry. Be able to transmit data over standard twisted pair cables as well as fiber optic. Maintain a low bit error rate for high quality image while operating at a very low power level. Be scalable.

The Future is Now

With flat panel displays already a common part of our everyday lives at work, home and industrial/commercial settings, deciding on a standard is a monumental decision that will affect all our lives. Engineers will have to champion their cause by applying both of these digital panel technologies to many practical products. Thus enabling the end user, whether it be in an industrial setting or a consumer setting, to benefit from both of these technologies.

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