Integrated

Circuit

Systems, Inc.

AV9108

CPU Frequency Generator

Block Diagram

AV 9108 RevB032195

General Description

The AV9108 offers a tiny footprint solution for generating two

simultaneous clocks. One clock, the REFCLK, is a fixed output

frequency which is the same as the input reference crystal (or

clock). The other clock, CLK1, can vary between 2 and 120

MHz, with up to 16 selectable preprogrammed frequencies

stored in internal ROM.

The ICS9108 is ideal for use in a 3.3V system. It can generate

a 66.66 MHz clock at 3.3V. In addition, the ICS9108 provides

a symmetrical wave form with a worst case duty cycle of 45/55.

The ICS9108 has very tight edge control between the CPU

clock and 2XCPU clock outputs, with a worst case skew of

250ps.

The device has advanced features which include on-chip loop

filters, tristate outputs, and power-down capability. A mini-

mum of external components - two decoupling capacitors and

an optional ferrite bead - are all that are required for jitter-free

operation. Standard versions for computer motherboard appli-

cations are the AV9108-03, AV9108-05 and the ICS9108-10.

Custom masked versions, with customized frequencies and

features, are available in 6-8 weeks for a small NRE fee.

Features

•• Runs up to 80 MHz at 3.3V

•• 50/50 typical duty cycle at 5V

•• ±250ps absolute jitter

•• Generates frequencies from 2 to 140 MHz

•• 2 to 32 MHz input reference frequency

•• Up to 16 frequencies stored internally

•• Patented on-chip Phase Locked Loop with VCO for clock

generation

•• Provides reference clock and synthesized clock

•• On-chip loop filter

•• Low power 0.8µ CMOS technology

•• 8-pin or 14-pin DIP or SOIC package