资 源 简 介
The CY2254A is a Clock Synthesizer/Driver that provides themulTIple clocks required for a PenTIum-based PC. TheCY2254A has low-skew outputs (< 250 ps between the CPUClocks, < 250 ps between the PCI Clocks). In addiTIon, theCY2254A CPU clock outputs have less than 200 ps cycle-to-cycle jitter. Finally, both the PCI and CPU clock outputsmeet the 1 V/ns slew rate requirement of a PenTIum processor-based system.The CY2254A accepts a 14.318 MHz reference signal as itsinput. The CY2254A has 2 PLLs, one of which generates theCPU and PCI clocks, and the other generates the I/O and KeyboardController or USB clocks. The CY2254A runs off eithera 3.3V or 5V supply.The CY2254A is available in two options. The −1 option supportsthe Intel Triton PCIset and provides a 12 MHz keyboardclock on pin 25. The −2 option provides a 48 MHz USB clockon pin 25 and supports the Cyrix® M1 processor.
