MK1449B
Sound/SCSI+Fast Ethernet Clock
Description
The MK1449B is the most cost effective way to
generate high quality, high frequency clock
outputs for SCSI plus Fast Ethernet devices, or
AC97 sound chips. Using Phase-Locked-Loop
(PLL) techniques, the device uses a standard
fundamental mode, inexpensive 14.31818 MHz
crystal or clock to produce two output clocks.
The device can accept either a crystal or clock
input. Also on the chip is the ability to generate a
1.25x clock of the reference plus the reference,
making it possible to generate 20 and 25 MHz
clocks from a 20 MHz crystal.
Features
• Packaged as 8 pin SOIC
• For Fast Ethernet plus SCSI on computer
motherboards
• For AC97 sound on computer motherboards
• Less than 1 ppm synthesis error
• Input crystal frequency of 14.31818 MHz
• Operating voltages of 3.0 to 5.5V
• Available in industrial temperature
• Full CMOS level outputs with 25mA drive
capability at TTL levels
• Ideal for oscillator replacement
• Advanced, low power CMOS process
Block Diagram
VDD GND
2
S1, S0
PLL
Clock
Synthesis
and Control
Circuitry
Crystal
Oscillator
X2
Output
Buffer
CLK1
14.31818MHz
crystal
X1
or clock
Output
Buffer
CLK2
1
Revision 120799
Printed 11/15/00
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose •CA•95126• (408)295-9800tel • www.icst.com
MDS 1449B C
ICS [ INTEGRATED CIRCUIT SYSTEMS ]
