The Western Digital WD90C51 is a 1.2 micron CMOS device designed specifically for Personal System/2 compatible color graphics in laptop computer environments. It integrates the functions of a color lookup table, digital to analog converters, bi-directional microprocessor interface, power saving features, and PS/2 compatible monitor detection logic.
The architecture consists of five major modules: the Address Register, the Pixel Mask Register, the color palette RAM, power down control, and the digital to analog converter with automatic power on reset. The device supports RS-343A and RS-170 compatible video signal outputs into 75 Ohm loads without external buffering.
| Technology | 1.25 Micron CMOS Technology |
|---|---|
| Package Type | 44-Pin PLCC Package |
| Color Lookup Table Size | 256 x 18 |
| D/A Converters | Triple 6 Bit |
| Linearity Error | +/- 1/4 LSB |
It is designed specifically for Personal System/2 compatible color graphics in a laptop computer environment.
It generates RS-343A compatible signals into a doubly-terminated 75 Ohm load and RS-170 compatible signals into a singly-terminated 75 Ohm load.
When the -PWRDN input is low, the entire WD90C51 enters an "IDLE" state where both the DAC and color palette RAM are turned off.