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Switching LVDS Graphics in a Laptop Computer

Switching LVDS Graphics in a Laptop Computer

Unlike desktop computers that have easily upgraded video graphics capabilities, laptops have historically been incapable of allowing such an upgrade. Ideally, laptop design would allow the graphics card to be an add-in feature. To permit this possibility, a simple solution would be to add a switch to the design that would select either internal graphics or the LVDS output of the add-in card. Because the MAX4889 can switch between two LVDS sources to a single destination, it is an ideal choice of switch for a laptop design.

For many years, video graphics have been a feature that consumers could upgrade at will in desktop computers. Early IBM computers were configured with either an MGA (monochrome graphics adapter) or a CGA (color graphics adapter). The consumer could pick the same model computer, but choose either graphics card, depending on the monitor selected. These early adapters evolved to become the VGA (video graphics array) standard, which could drive either monochrome or color graphics with many colors or gray levels, respectively.


Video graphics have progressed so much that the GPU (graphics processor unit) has become one of the most sophisticated processors in the desktop computer. These processors have evolved into miniature complete systems with as much as 512MB of memory and very sophisticated floating-point processing, as well as multiple outputs to drive various monitors.

In recent years, laptops have surpassed desktop computers in unit volume sold. The cost of the laptops has dropped dramatically, and many consumers are viewing laptops as desktop replacements. A 17in laptop with a full size keyboard makes a very reasonable replacement for a desktop. With WiFi in the home, the consumer only needs to plug in the AC power to keep the unit charged, and all the wires, keyboard, mouse, and speakers are gone. However, high-end laptops are also being used by the gamer and the at-home/telecommuting professional, both of whom need a large screen and full-size keyboard.