The W83194R-630A is a Clock Synthesizer for SiS 540/630 chipset. W83194R-630A provides all clocks required for high-speed RISC or CISC microprocessor such as AMD,Cyrix,Intel Pentium, Pentium II and also provides 16 different frequencies of CPU clocks frequency setting. All clocks are externally selectable with smooth transitions. The W83194R-630A makes SDRAM in synchronous or asynchronous frequency with CPU clocks. The W83194R-630A provides I2C serial bus interface to program the registers to enable or disable each clock outputs and W83194R-630A provides the 0.5%, 0.75% center type and 0~0.5% down type spread spectrum to reduce EMI. The W83194R-630A accepts a 14.318 MHz reference crystal as its input and runs on a 3.3V supply. High drive PCI and SDRAM CLOCK outputs typically provide greater than 1 V /ns slew rate into 30 pF loads. CPU CLOCK outputs typically provide better than 1 V /ns slew rate into 20 pF loads as maintaining 50 5% duty cycle. The fixed frequency outputs as REF, 24MHz, and 48 MHz provide better than 0.5V /ns slew rate.