Integrated
Circuit
Systems, Inc.
AV9154A
0174C—04/06/06
Low-Cost 16-Pin Frequency Generator
The AV9154A is a 0.8mm version of the industry leading
AV9154.
Like the AV9154, the AV9154A is a low-cost
frequency generator designed for general purpose PC and
disk drive applications.
However, because the AV9154A
uses 0.8mm technology and the latest phase-locked loop
architecture, it offers performance advantages that enable
the device to be sold into Pentium systems.
The AV9154A guarantees a 45/55 duty cycle over all
frequencies. In addition, a worst case jitter of ±250ps is
specified at Pentium frequencies.
The CPU clock offers the unique feature of smooth, glitch-
free transitions from one frequency to the next, making this
the ideal device to use when slowing the CPU speed. The
AV9154A makes a gradual transition between frequencies
so that it obeys the Intel cycle-to-cycle timing specifications
for 486 and Pentium systems.
The AV9154A-42 and AV9154A-43 devices offer features
specifically for green PCs. The AV9154A-42 and -43 have a
single pin that, when pulled low, will smoothly slow the 2XCPU
clock to 8 MHz. This is ideal for dynamic DX microprocessors.
The AV9154A-43 not only has the slow clock feature, but
also offers a glitch-free stop clock for static SX
microprocessors.
The STOPCLK# pin, when pulled low,
enables the 2XCPU clock to go low only after completing its
last full cycle. The clock continues to run internally, and will
be output again on the first full cycle immediately following
stop clock disable.
The simultaneous 2X and 1X CPU clocks offer controlled
skew to within 500ps of each other (-42 only).
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. Consult ICS for all your clock
generation needs.
Compatible with 386, 486 and Pentium CPUs
45/55 Duty cycle
Runs up to 66 MHz at 3.3V
Single pin can slow clock to 8 MHz (on -42 and -43)
Single pin can stop the CPU clock glitch-free (on -43)
Very low jitter, ±250ps for Pentium frequencies
1X and 2X CPU clocks skew controlled to ±250ps (-42
only)
Smooth transitions between all CPU frequencies
Slow frequency ramp at power-on avoids CPU lock-up
16-pin PDIP or 150-mil skinny SOIC packages
0.8
m CMOS technology
Applications
Computer motherboards: The AV9154A-ST replaces crystals
and oscillators, saving board space, component cost, part
count and inventory costs. It produces a switchable CPU
clock and up to four fixed clocks to drive floppy disk,
communications, super I/O, Bus, and/or keyboard devices.
The small package and 3.3V operation is perfect for handheld
computers.
Features
General Description
Block Diagram