ICST AV9155C-36CN20, AV9155C-36CM20, AV9155C-23CN20, AV9155C-23CM20, AV9155C-02CN20 Datasheet

Integrated

AV9155C

Circuit

Systems, Inc.

Low Cost 20-Pin Frequency Generator

General Description

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, glitchfree 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:

Features

•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.

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 PentiumÔ frequencies
AV9155C-36	Features a special 40 MHz SCSI clock

Block Diagram

Pentium is a trademark of Intel Corporation.

AV9155C Rev F 12/13/00

AV9155C

Pin Configuration

20-Pin DIP or SOIC

20-Pin DIP or SOIC

Pin Descriptions for AV9155C-01, -02

	PIN	PIN NAME	TYPE	DESCRIPTION
	NUMBER
	1	1.843 MHz	Output	1.84 MHz clock output.
	2	X2	Output	Crystal connection.
	3	X1	Input	Crystal connection.
	4	VDD	-	Digital power supply (3.3V or 5.0V).
	5	GND	-	Digital Ground.
	6	16 MHz/32 MHz	Output	16 MHz (-01) or 32 MHz (-02) clock output.
	7	24 MHz	Output	24 MHz floppy disk/combination I/O clock output.
	8	12 MHz	Output	12 MHz keyboard clock output.
	9	AGND	-	Analog ground (original version).
	10	OE	Input	Output enable. Tristates all outputs when low. (Has internal pull-up.)
	11	FS2	Input	CPU clock frequency select #2. (Has internal pull-up.)
	12	PD#	Input	Power-down. Shuts off entire chip when low. (Has internal pull-up.)
	13	14.318 MHz	Output	14.318 MHz reference clock output.
	14	14.318 MHz	Output	14.318 MHz reference clock output.
	15	GND	-	Digital ground.
	16	VDD	-	Digital power supply (3.3V or 5.0V).
	17	2XCPU	Output	2X CPU clock output.
	18	CPU	Output	1X CPU clock output.
	19	FS1	Input	CPU clock frequency select #1. (Has internal pull-up.)
	20	FS0	Input	CPU clock frequency select #0. (Has internal pull-up.)

2

AV9155C

Functionality - AV9155C-01

(Using 14.318 MHz input.All frequencies in MHz.)

CLOCK#2CPUand2XCPU

FS2	FS1	FS0	2XCPU	CPU
(Pin 11)	(Pin 19)	(Pin 20)	(Pin 17)	(Pin 18)
0	0	0	8	4
0	0	1	16	8
0	1	0	32	16
0	1	1	40	20
1	0	0	50	25
1	0	1	66.66	33.33
1	1	0	80*	40*
1	1	1	100*	50*

*VDD minimum 3.15V.

PERIPHERAL CLOCKS

COMMCLK	BUSCLK	FDCLK	KBCLK
(Pin 1)	(Pin 6)	(Pin 7)	(Pin 8)
1.843	16	24	12

REFERENCE CLOCKS

REFCLK1	REFCLK2
(Pin 13)	(Pin 14)
14.318	14.318

Functionality - AV9155C-02

(Using 14.318 MHz input.All frequencies in MHz.)

CLOCK#2CPUand2XCPU

FS2	FS1	FS0	2XCPU	CPU
(Pin 11)	(Pin 19)	(Pin 20)	(Pin 17)	(Pin 18)
0	0	0	8	4
0	0	1	16	8
0	1	0	32	16
0	1	1	40	20
1	0	0	50	25
1	0	1	66.66	33.33
1	1	0	80*	40*
1	1	1	100*	50*

* VDD minimum 3.15V

PERIPHERAL CLOCKS

COMMCLK	BUSCLK	FDCLK	KBCLK
(Pin 1)	(Pin 6)	(Pin 7)	(Pin 8)
1.843	32	24	12

REFERENCE CLOCKS

REFCLK1	REFCLK2
(Pin 13)	(Pin 14)
14.318	14.318

Frequency Transitions

Using an Input Clock as Reference

A key feature of the AV9155C is its ability to provide smooth, glitch-free frequency transitions on the CPU and 2XCPU clocks when the frequency select pins are changed. These frequency transitions do not violate the Intel 486 specification of less than 0.1% frequency change per clock period.

The AV9155C is designed to accept a 14.318 MHz crystal as the input reference. With some external changes, it is possible to use a crystal oscillator or clock input. Please see application note AN04 for details on driving the AV9155C with a clock.

3

AV9155C

Pin Configuration

20-Pin DIP or SOIC

20-Pin DIP or SOIC

Pin Descriptions for AV9155C-23, -36

	PIN	PIN	TYPE	DESCRIPTION
	NUMBER	NAME
	1	1.843/40 MHz	Output	1.84 MHz (-23)/40 MHz SCSI (-36) clock output.
	2	X2	Output	Crystal connection.
	3	X1	Input	Crystal connection.
	4	VDD	-	Digital power supply (3.3V or 5.0V).
	5	GND	-	Digital ground.
	6	16 MHz/15 MHz	Output	16 MHz (-23)/15 MHz (-36) clock output.
	7	24 MHz	Output	24 MHz floppy disk/combination I/O clock output.
	8	12 MHz	Output	12 MHz keyboard clock output.
	9	AGND	-	Analog ground (original version).
	10	OE	Input	Output enable. Tristates all outputs when low. (Has internal pull-up.)
	11	FS2	Input	CPU clock frequency select #2. (-23 has internal pull-up.)
	12	PD#	Input	Power-down. Shuts off entire chip when low. (Has internal pull-up.)
	13	14.318 MHz	Output	14.318 MHz reference clock output.
	14	14.318 MHz	Output	14.318 MHz reference clock output.
	15	GND	-	Digital ground.
	16	VDD	-	Digital power supply (3.3V or 5.0V).
	17	2XCPU	Output	2X CPU clock output.
	18	CPU	Output	1X CPU clock output.
	19	FS1	Input	CPU clock frequency select #1. (-23 has internal pull-up.)
	20	FS0	Input	CPU clock frequency select #0. (-23 has internal pull-up.)

4

AV9155C

Functionality - AV9155C-23

(Using 14.318 MHz input.All frequencies in MHz.)

CLOCK#2CPUand2XCPU

FS2	FS1	FS0	2XCPU	CPU
(Pin 11)	(Pin 19)	(Pin 20)	(Pin 17)	(Pin 18)
0	0	0	75*	37.5*
0	0	1	32	16
0	1	0	60	30
0	1	1	40	20
1	0	0	50	25
1	0	1	66.66	33.33
1	1	0	80*	40*
1	1	1	52	26

*VDDminimum3.15V

Functionality - AV9155C-36

(Using 14.318 MHz input.All frequencies in MHz.)

CLOCK#2CPUand2XCPU

FS2	FS1	FS0	2XCPU	CPU
(Pin 11)	(Pin 19)	(Pin 20)	(Pin 17)	(Pin 18)
0	0	0	8	4
0	0	1	16	8
0	1	0	60	30
0	1	1	40	20
1	0	0	50	25
1	0	1	66.66	33.33
1	1	0	80*	40*
1	1	1	100*	50*

*VDDminimum3.15V

PERIPHERAL CLOCKS

COMMCLK	BUSCLK (Pin	FDCLK	KBCLK
(Pin 1)	6)	(Pin 7)	(Pin 8)
1.843	16	24	12

REFERENCE CLOCKS

REFCLK1	REFCLK2
(Pin 13)	(Pin 14)
14.318	14.318

PERIPHERAL CLOCKS

SCSICLK	BUSCLK (Pin	FDCLK	KBCLK
(Pin 1)	6)	(Pin 7)	(Pin 8)
40	15	24	12

REFERENCE CLOCKS

REFCLK1	REFCLK2
(Pin 13)	(Pin 14)
14.318	14.318

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