TLC34077

The TLC34077 Video Interface Palette (VIP) is designed to provide lower system cost with a higher level of integration by incorporating all the high-speed timing, synchronizing, and multiplexing logic usually associated with graphics systems into one device, thus greatly reducing chip count. Since all high-speed signals (excluding the clock source) are contained on-chip, RF noise considerations are simplified. Maximum flexibility is provided through the pixel multiplexing scheme, which allows for 32-, 16-, and 8-bit pixel buses to be accommodated without any circuit modification. The TLC34077 is software compatible with the IMSG176/8 and Brooktree BT476/8 color palettes.

The TLC34077 VIP is pin-for-pin compatible with the TLC34076 VIP, but with a reduced feature set optimized for cost sensitive, high-performance PC graphics applications. The TLC34077 is compatible with a variety of graphics processors, including the ATI 68800 mach 32 series of graphics accelerators. The TLC34077 features a separate VGA bus that allows data from the feature connector of most VGA-supported personal computers to be fed directly into the palette without the need for external data multiplexing. This allows a replacement graphics board to remain downward compatible by utilizing the existing graphics circuitry often located on the motherboard.

The 24- and 16-bit true-color modes that are provided allow bits of color information to be transferred directly from the pixel port to the DACs.

The TLC34077 has a 256-by-24 color lookup table with triple 8-bit video D/A converters capable of directly driving a doubly terminated 75-W line. Sync generation is incorporated on the green output channel. Clocking is provided through one of two TTL-compatible inputs and is software selectable. The video clock output provides a software-selected divide ratio of the chosen clock input.