ICST AV9155C-44CW20, ICS9155C-44CW20 Datasheet

Integrated
Circuit
Systems, Inc.

AV9155C-44

General Description Features

Block Diagram

Low Cost 20-Pin Frequency Generator

9155-44 Rev D 02/12/98

The AV9155C-44 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, glitch­free transitions from one frequency to the next, making this
ideal device to use whenever slowing the CPU speed. The
AV9155C-44 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.

 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

Pin Configuration

20-Pin DIP or SOIC

THIS DATA SHEET (AV9155C-44) IS AN ADDENDUM TO THE EXISTING AV9155C
DATA SHEET. ALL INFORMATION IN THIS DATA SHEET SUPERSEDES THE DATA
FOUND IN THE ORIGINAL AV9155C DATA SHEET.

ICS reserves the right to make changes in the device data identified in this publication
without further notice. ICS advises its customers to obtain the latest version of all
device data to verify that any information being relied upon by the customer is current
and accurate.

2

AV9155C-44

Pin Descriptions for AV9155C-44

PIN NUMBER PIN NAME TYPE DESCRIPTION

1 3.529 MHz OUT 3.529 MHz reference clock output.
2 X2 OUT CRYSTAL connection.
3 X1 IN CRYSTAL connection.
4 VDD PWR DIGITAL POWER SUPPLY (+5V).
5 GND PWR Digital GROUND.
6 20 MHz OUT 20 MHz clock output.
7 N/C - Not internally connected.
8 30 MHz OUT 30 MHz keyboard clock output.
9 AGND PWR ANALOG GROUND (original version).

10 N/C - Not internally connected.
11 OE# IN

OUTPUT ENABLE. Tristates 2XCPU output when high. (Has

internal pull-up.)
12 N/C - Not internally connected.
13 16 MHz OUT 16 MHz reference clock output.
14 N/C - Not internally connected.
15 GND PWR Digital GROUND.
16 VDD PWR DIGITAL POWER SUPPLY (+5V).
17 2XCPU OUT CPU clock output.
18 N/C - Not internally connected.
19 FS1 IN CLOCK frequency SELECT #1. (Has internal pull-up.)
20 FS0 IN CLOCK frequency SELECT #0. (Has internal pull-up.)