MK1432/MK1434
Green PC and Local Bus Clock Source
MDS 1432 G
1
Revision 060101
Integrated Circuit Systems, Inc. 525 Race Street San Jose CA 95126 (408)295-9800 www.icst.com
The MK1432 and MK1434 are low cost, high
performance triple clock synthesizers for green PC and
local bus desktop and notebook applications. Using
analog Phase-Locked Loop (PLL) techniques, the
devices accept a 14.318 MHz crystal input to produce
multiple output clocks up to 100 MHz. They provide
selectable 2XCPU and CPU, selectable local bus clock,
ISA clock, and one fixed peripheral clock. The chips
support PCI and VL buses. The fixed clock is either
24MHz or 40MHz. The devices can operate at 5V or
3.3V up to and including 80MHz on the 2XCPU clock.
The Power Saving pin causes the CPU clocks to
smoothly transition to 33.33 MHz for Pentiums, and
16.67 MHz for 486DX4. In addition, a single pin can be
made to slow DX2s to 8 MHz.
Crystal
Oscillator
VDD
GND
X1
X2
CPU
Clocks
2XCPU
BCLK
Output
Buffer
FS0
FS1
14.318 MHz
crystal
Block Diagram
Description
Features
Output
Buffer
Output
Buffer
Output
Buffer
Output
Buffer
÷2
CPU
40.00 (MK1434)
or 24.00 MHz
(MK1432)
Packaged in 16 pin narrow (150 mil) SOIC
Supports all Pentium Processor timing specs
Supports synchronous and asynchronous local bus
Selectable local bus frequencies of 25, 33, or
50MHz
SCSI or VL bus 40MHz clock on MK1434
Floppy or super I/O clock on MK1432
Single Power Saving pin switches to low power
mode (for 486 and Pentium)
5V or 3.3V (up to 80MHz) operation
Smooth transitions for Pentium and 486 based
Green PC
Low skew (<250ps) Pentium compatible
2X and 1X outputs
Duty cycle of 45/55 up to 100 MHz
25mA output drive capability at TTL levels
Compatible with all popular microprocessors
Packaged in 16 pin narrow SOIC
For Early Clock support, consult MicroClock
FS2
14.318 MHz
Fixed
Clock
PS
BCLKS
Local
Bus
Clock