Integrated
Circuit
Systems, Inc.
AV9155
Low Cost 20-Pin Frequency Generator
General Description
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:
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
AV9155
is a third generation
device, and uses ICSs 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 Pentium™ frequencies
AV9155C-36 Features a special 40 MHz SCSI clock
Block Diagram
Pentium is a trademark of Intel Corporation.
9155 Rev B 8/24/98
AV9155
Pin Configuration
20-Pin DIP or SOIC
20-Pin DIP or SOIC
Pin Descriptions for AV 9155-01, 9155-02
PIN
N UM BER
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
X2
X1
VDD
GN D
16 M Hz/32 M Hz
24 M Hz
12 M Hz
AGN D
OE
FS2
PD#
14.318 M Hz
14.318 M Hz
GN D
VDD
2XC PU
C PU
FS1
FS0
PIN N AM E
1.843 M Hz
TYPE
O utput
O utput
Input
-
-
O utput
O utput
O utput
-
Input
Input
Input
O utput
O utput
-
-
O utput
O utput
Input
Input
1.84 M Hz clock output.
C rystal connection.
C rystal connection.
Digital power supply (3.3V or 5.0V).
Digital Ground.
16 M Hz (-01) or 32 M Hz (-02) clock output.
24 M Hz floppy disk/combination I/O clock output.
12 M Hz keyboard clock output.
Analog ground (original version).
O utput enable. Tristates all outputs when low. (Has internal pull-up.)
C PU clock frequency select #2. (Has internal pull-up.)
Power-down. Shuts off entire chip when low. (Has internal pull-up.)
14.318 M Hz reference clock output.
14.318 M Hz reference clock output.
Digital ground.
Digital power supply (3.3V or 5.0V).
2X C PU clock output.
1X C PU clock output.
C PU clock frequency select #1. (Has internal pull-up.)
C PU clock frequency select #0. (Has internal pull-up.)
DESC RIPTIO N
2
AV9155
Functionality
- AV9155-01
(Using 14.318 MHz input. All frequencies in MHz.)
CLOCK#2 CPU and 2XCPU
FS2
(Pin 11)
0
0
0
0
1
1
1
1
FS1
(Pin 19)
0
0
1
1
0
0
1
1
FS0
(Pin 20)
0
1
0
1
0
1
0
1
2XCPU
(Pin 17)
8
16
32
40
50
66.66
80*
100*
CPU
(Pin 18)
4
8
16
20
25
33.33
40*
50*
PERIPHERAL CLOCKS
COMMCLK
(Pin 1)
1.843*
BUSCLK
(Pin 6)
16*
FDCLK
(Pin 7)
24*
KBCLK
(Pin 8)
12*
REFERENCE CLOCKS
REFCLK1
(Pin 13)
14.318
REFCLK2
(Pin 14)
14.318
*5V only.
Functionality - AV9155-02
CLOCK#2 CPU and 2XCPU
FS2
(Pin 11)
0
0
0
0
1
1
1
1
FS1
(Pin 19)
0
0
1
1
0
0
1
1
FS0
(Pin 20)
0
1
0
1
0
1
0
1
(Using 14.318 MHz input. All frequencies in MHz.)
PERIPHERAL CLOCKS
2XCPU
(Pin 17)
8
16
32
40
50
66.66
80*
100*
CPU
(Pin 18)
4
8
16
20
25
33.33
40*
50*
COMMCLK
(Pin 1)
1.843*
BUSCLK
(Pin 6)
32*
FDCLK
(Pin 7)
24*
KBCLK
(Pin 8)
12*
REFERENCE CLOCKS
REFCLK1
(Pin 13)
14.318
REFCLK2
(Pin 14)
14.318
*5V only.
Frequency Transitions
A key feature of the
AV9155
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.
Using an Input Clock as Reference
The
AV9155
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
AV9155
with a clock.
3
AV9155
Pin Configuration
20-Pin DIP or SOIC
20-Pin DIP or SOIC
Pin Descriptions for AV9155-23, -36
PIN
NUMBER
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
X2
X1
VDD
GND
16 MHz/15 MHz
24 MHz
12 MHz
AGND
OE
FS2
PD#
14.318 MHz
14.318 MHz
GND
VDD
2XCPU
CPU
FS1
FS0
PIN
NAME
1.843/40 MHz
TYPE
Output
Output
Input
-
-
Output
Output
Output
-
Input
Input
Input
Output
Output
-
-
Output
Output
Input
Input
DESCRIPTION
1.84 MHz (-23)/40 MHz SCSI (-36) clock output.
Crystal connection.
Crystal connection.
Digital power supply (+5V)
Digital ground.
16 MHz (-23)/15 MHz (-36) clock output.
24 MHz floppy disk/combination I/O clock output.
12 MHz keyboard clock output.
Analog ground (original version).
Output enable. Tristates all outputs when low. (Has internal pull-up.)
CPU clock frequency select #2. (-23 has internal pull-up.)
Power-down. Shuts off entire chip when low. (Has internal pull-up.)
14.318 MHz reference clock output.
14.318 MHz reference clock output.
Digital ground.
Digital power supply (3.3V or 5.0V).
2X CPU clock output.
1X CPU clock output.
CPU clock frequency select #1. (-23 has internal pull-up.)
CPU clock frequency select #0. (-23 has internal pull-up.)
4
AV9155
Functionality
- AV9155-23
(Using 14.318 MHz input. All frequencies in MHz.)
CLOCK#2 CPU and 2XCPU
FS2
(Pin 11)
0
0
0
0
1
1
1
1
FS1
(Pin 19)
0
0
1
1
0
0
1
1
FS0
(Pin 20)
0
1
0
1
0
1
0
1
2XCPU
(Pin 17)
75*
32
60
40
50
66.66
80*
52
CPU
(Pin 18)
37.5*
16
30
20
25
33.33
40*
26
PERIPHERAL CLOCKS
COMMCLK
(Pin 1)
1.843
BUSCLK
(Pin 6)
16*
FDCLK
(Pin 7)
24
KBCLK
(Pin 8)
12
REFERENCE CLOCKS
REFCLK1
(Pin 13)
14.318
REFCLK2
(Pin 14)
14.318
*5V only
Functionality
- AV9155-36
(Using 14.318 MHz input. All frequencies in MHz.)
CLOCK#2 CPU and 2XCPU
FS2
(Pin 11)
0
0
0
0
1
1
1
1
FS1
(Pin 19)
0
0
1
1
0
0
1
1
FS0
(Pin 20)
0
1
0
1
0
1
0
1
2XCPU
(Pin 17)
8
16
60
40
50
66.66
80*
100*
CPU
(Pin 18)
4
8
30
20
25
33.33
40*
50*
PERIPHERAL CLOCKS
SCSICLK
(Pin 1)
40*
BUSCLK
(Pin 6)
15*
FDCLK
(Pin 7)
24*
KBCLK
(Pin 8)
12*
REFERENCE CLOCKS
REFCLK1
(Pin 13)
14.318
REFCLK2
(Pin 14)
14.318
*5V only
5
京公网安备 11010802033920号
EEWORLD
