Integrated

Circuit

Systems, Inc.

General Description

Features

AV9155

Block Diagram

9155 Rev B 8/24/98

Low Cost 20-Pin Frequency Generator

The AV9155 is a low cost frequency generator designed spe-

cifically for desktop and notebook PC applications. Its CPU

clocks provide all necessary CPU frequencies for 286, 386 and

486 systems, including support for the latest speeds of proces-

sors. 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 AV9155

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 AV9155.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

sinceApril 1990, and is the leader in the area of multiple output

clocks on a single chip. The AV9155 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.

PART

DESCRIPTION

AV9155C-01

Motherboard clock generator with 16 MHz BUS CLK

AV9155C-02

Motherboard clock generator with 32 MHz BUS CLK

AV9155C-23

Includes Pentium

™ frequencies

AV9155C-36

Features a special 40 MHz SCSI clock