General Description

The ICS9159-05 is a low cost frequency generator designed specifically for Pentium/Pentium Pro systems. The integrated buffer minimizes skew and provides the early CPU clock required by some chipsets such as the OPTi VIPER. A 14.318 MHz XTAL oscillator provides the reference clock to generate standard Pentium frequencies. The CPU clock makes gradual frequency transitions without violating the PLL timing of internal micro-processor clock multipliers.

The synchronous bus frequencies are selectable as CPU for local bus or CPU/2 for PCI bus support. Green PC systems are supported through power-down, doze, and glitch-free stop clock modes.

Features

• Four CPU clocks operate up to 66.6 MHz at 3.3V with glitch-free start and stop plus smooth transitions

• 3-6ns early CPU clock supports OPTi VIPER systems

• Selection of 6 frequencies, tristate, or power-down

• Six BUS clocks support local PCI bus operation

• Skew window between synchronous outputs

• Integrated buffer outputs drive up to 30pF loads

• 3.0V - 3.7V supply range

• 28-pin DIP or 28-pin 300-mil SOIC package

Applications

• Ideal for green Pentium/Pentium Pro and 486 PCI systems such as Pentium, PowerPC™ etc.