Integrated

Circuit

Systems, Inc.

General Description

Features

AV9155C

Block Diagram

AV9155C Rev F 12/13/00

Low Cost 20-Pin Frequency Generator

The AV9155C is a low cost frequency generator designed

specifically for desktop and notebook PC applications with

either 3.3V or 5.0V power supply voltage. Its CPU clocks

provide all necessary CPU frequencies for 286, 386 and 486

systems, including support for the latest speeds of processors.

The device uses a 14.318 MHz crystal to generate the CPU

and all peripheral clocks for integrated desktop motherboards.

The dual 14.318 MHz clock outputs allows one output for the

system and one to be the input to an ICS graphics frequency

generator such as the AV9194.

The CPU clock offers the unique feature of smooth, glitch-

free transitions from one frequency to the next, making this

ideal device to use whenever slowing the CPU speed. The

AV9155C makes a gradual transition between frequencies, so

that it obeys the Intel cycle-to-cycle timing specification for

486 systems. The simultaneous 2X and 1X CPU clocks offer

controlled skew to within 1.5ns (max) of each other.

ICS offers several versions of the AV9155C. The different

devices are shown below:

•

Compatible with 286, 386, and 486 CPUs

•

Supports turbo modes

•

Generates communications clock, keyboard clock,

floppy disk clock, system reference clock, bus clock

and CPU clock

•

Output enable tristates outputs

•

Up to 100 MHz at 5V or 3.3V

•

20-pin DIP or SOIC

•

All loop filter components internal

•

Skew-controlled 2X and 1X CPU clocks

•

Power-down option

ICS has been shipping motherboard frequency generators

since April 1990, and is the leader in the area of multiple

output clocks on a single chip. The AV9155C is a third

generation device, and uses ICS’s patented analog CMOS

phase-locked loop technology for low phase jitter. ICS offers

a broad family of frequency generators for motherboards,

graphics and other applications, including cost-effective

versions with only one or two output clocks. Consult ICS for

all of your clock generation needs.

Pentium is a trademark of Intel Corporation.

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