CY2254A

Y2254A www.DataSheet4U.com CY2254A Pentium® Processor Compatible Clock Synthesizer/Driver Features Multiple clock outputs to meet requirements of most Pentium® motherboards — Four pin-selectable CPU clocks @ 66.66 MHz, 60.0 MHz, and 50.0 MHz for support of Intel Triton™ PCIset based PC — 55.0 MHz pin-selectable CPU clock also available (2 option only) — Six PCI clocks at 1/2 CPU Clock frequency — One I/O clock @ 24 MHz — One Keyboard Controller clock @ 12 MHz (1 option) or one Universal Serial Bus clock @ 48 MHz (2 option) — Two Ref. clocks @ 14.318 MHz — Ref. 14.318 MHz Xtal oscillator input CPU clock jitter < 200 ps cycle-to-cycle Low skew outputs — < 250 ps between CPU clocks — < 250 ps between PCI clocks — < 500 ps between CPU and PCI clocks (2 option) — CPU clock leads PCI clock by +1 ns min. to +4 ns max. (1 option) Freq. stability = 0.01% (max.) Output duty cycle 45% min. to 55% max. Test mode support (1 option only) 3.3V or 5.0V operation Internal pull-up resistors on S0, S1, and OE inputs Functional Description The CY2254A is a Clock Synthesizer/Driver that provides the multiple clocks required for a Pentium-based PC. The CY2254A has low-skew outputs (< 250 ps between the CPU Clocks, < 250 ps between the PCI Clocks). In addition, the CY2254A CPU clock outputs have less than 200 ps cycle-to-cycle jitter. Finally, both the PCI and CPU clock outputs meet the 1 V/ns slew rate requirement of a Pentium processor-based system. The CY2254A accepts a ...