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
MK1432/MK1434
Green PC and Local Bus Clock Source
MDS 1432 G 2 Revision 060101
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800 • www.icst.com
1432 1434 Name Type Description
11FS2 I Select 2 for 2XCPU and CPU frequencies. See table above. Internal Pull-Up.
2 2 X2 O Crystal connection. Connect to 14.31818 MHz crystal.
3 3 X1 I Crystal connection. Connect to 14.31818 MHz crystal or clock.
4 4 VDD P Connect to +5V or 3.3V. Must be same voltage as pin 13.
5 5 GND P Connect to ground.
6 6 BCLK O Local Bus Clock output. See table above.
7 - 24M O 24.00 MHz clock output (MK1432 only).
- 7 40M O 40.00 MHz clock output (MK1434 only).
8 8 PS I
Power Saving pin. Smoothly changes CPU to/from 33.33 and 16.67 MHz. IPU.
9 9 BCLKS TI Local Bus Clock Select pin. See table above.
10 10 FS0 I Select 0 for 2XCPU and CPU frequencies. See table above. Internal Pull-Up.
11 11 14.3M O 14.318 MHz Reference Clock Output.
12 12 GND P Connect to ground.
13 13 VDD P Connect to +5V or 3.3V. Must be same voltage as pin 4.
14 14 CPU O CPU Clock output. See table above for frequencies.
15 15 2XCPU O 2X CPU Clock output. See table above for frequencies.
16 16 FS1 I Select 1 for 2XCPU and CPU frequencies. See table above. Internal Pull-Up.
Pin Descriptions
PS FS2 FS1 FS0 2XCPU CPU
1000 16.00 8.00
1001
100.00 note 3
50.00 note3
1010 80.00 40.00
1 0 1 1 75.00 37.50
1 1 0 0 40.00 20.00
1 1 0 1 50.00 25.00
1 1 1 0 66.66 33.33
1 1 1 1 60.00 30.00
0 X X X 33.33 16.67
CPU Clock Decoding Table (in MHz)
Notes:
1. Actual frequencies are within 0.05% of those shown.
2. Transitions between mean frequencies on any CPU pin are
smooth, and do not violate Intel’s 0.1% per cycle specification.
3. These selections are not guaranteed to operate at 3V.
4. M = mid level. Leave pin tri-stated, unconnected, or floating to
select this level.
5. X = don’t care (either 0 or 1).
Key: TI = Tri-level Input, I = Input, O = output, P = power supply connection
Pin Assignment
1
89
16
2
3
4
5
6
7 10
11
12
13
14
15
FS2
X2
24M
BCLK
VDD
GND
X1
PS
FS1
14.3M
CPU
2XCPU
VDD
GND
BCLKS
FS0
BCLKS BCLK (MHz)
025.00
M 33.33
1 50.00
1
89
16
2
3
4
5
6
7 10
11
12
13
14
15
FS2
X2
40M
BCLK
VDD
GND
X1
PS
FS1
14.3M
CPU
2XCPU
VDD
GND
BCLKS
FS0
Local Bus Clock Decoding Table (in MHz)
MK1432/MK1434
Green PC and Local Bus Clock Source
MDS 1432 G 3 Revision 060101
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800 • www.icst.com
Electrical Specifications
Notes: 1. Stresses beyond those listed under Absolute Maximum Ratings could cause permanent damage to the
device. Prolonged exposure to levels above the operating limits but below the Absolute Maximums may
affect device reliability.
2. With 2XCPU clock at 66.66MHz, and BCLK at 33.33MHz
Parameter Conditions Minimum Typical Maximum Units
ABSOLUTE MAXIMUM RATINGS (note 1)
ABSOLUTE MAXIMUM RATINGS (note 1)
Supply voltage, VDD Referenced to GND 7 V
Inputs and Clock Outputs Referenced to GND -0.5 VDD+0.5 V
Ambient Operating Temperature 0 70 °C
Soldering Temperature Max of 20 seconds 260 °C
Storage temperature -65 150 °C
DC CHARACTERISTICS (VDD = 5V unless noted)
DC CHARACTERISTICS (VDD = 5V unless noted)
Operating Voltage, VDD 3.0 5.5 V
Input High Voltage, VIH 2 V
Input Low Voltage, VIL 0.8 V
Mid-level pin Input High Voltage, VIH Pin 9 only VDD-0.5 V
Mid-level pin Input Low Voltage, VIL Pin 9 only 0.5 V
Output High Voltage, VOH IOH=-25mA 2.4 V
Output Low Voltage, VOL IOL=25mA 0.4 V
Output High Voltage, VOH VDD=3.3V, IOH=-8mA 2.4 V
Output Low Voltage, VOL VDD=3.3V, IOL=8mA 0.4 V
Operating Supply Current, IDD No Load, note 2 40 mA
Operating Supply Current, IDDPS No Load, PS=0 27 mA
Short Circuit Current Each output (except X2) ±100 mA
On-Chip Pull-up Resistor Pins 1, 8, 10, 16 250 kΩ
Input Capacitance 7 pF
AC CHARACTERISTICS (VDD = 5V unless noted)
AC CHARACTERISTICS (VDD = 5V unless noted)
Input Frequency 14.31818 MHz
Output Clock Rise Time 0.8 to 2.0V 1.5 ns
Output Clock Fall Time 2.0 to 0.8V 1.5 ns
Output Clock Duty Cycle At VDD/2 45 49 to 51 55 %
Cycle to Cycle Jitter, CPU Clocks 1000 ps
Absolute Clock Period Jitter 14-40 MHz clocks -500 500 ps
Skew of 2XCPU with respect to CPU Rising edges at 1.5V -250 0 250 ps
Transition time, 33.3MHz to 66.6MHz VDD=3.3 or 5V 3 ms
Transition time, 66.6MHz to 33.3MHz VDD=3.3 or 5V 2 ms
External Components
The MK1432/4 requires a minimum number of external components for proper operation. Decoupling capacitors of
0.1µF should be connected between VDD and GND, as close to the MK1432/4 as possible. A series termination
resistor of 33Ω may be used for each clock output. The device does not require (nor do we recommend) capacitors
connected to the crystal pins. The 14.31818 MHz crystal must be connected as close to the chip as possible.
Recommended load capacitance for the crystal is 12pF.
MK1432/MK1434
Green PC and Local Bus Clock Source
MDS 1432 G 4 Revision 060101
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800 • www.icst.com
While the information presented herein has been checked for both accuracy and reliability, MicroClock Incorporated assumes no responsibility for either
its use or for the infringement of any patents or other rights of third parties, which would result from its use. No other circuits, patents, or licenses are
implied. This product is intended for use in normal commercial applications. Any other applications such as those requiring extended temperature
range, high reliability, or other extraordinary environmental requirements are not recommended without additional processing by MicroClock.
MicroClock reserves the right to change any circuitry or specifications without notice. MicroClock does not authorize or warrant any MicroClock
product for use in life support devices or critical medical instruments.
b
D
E H
e
QcA
h x 45°
Package Outline and Package Dimensions
Ordering Information
Part/Order Number Marking Fixed Output Clock Frequency Package Temperature
MK1432S MK1432S 24 MHz 16 pin SOIC 0-70°C
MK1434S MK1434S 40 MHz 16 pin SOIC 0-70°C
MK1432STR MK1432S - Add Tape & Reel -
MK1434STR MK1434S - Add Tape & Reel -
16 pin SOIC narrow
Inches
Inches
Millimeters
Millimeters
Symbol Min Max Min Max
A0.055 0.070 1.397 1.778
b 0.013 0.019 0.330 0.483
c 0.007 0.010 0.191 0.254
D 0.385 0.400 9.779 10.160
E0.150 0.160 3.810 4.064
H 0.225 0.245 5.715 6.223
e
.050 BSC
.050 BSC
1.27 BSC
1.27 BSC
h 0.016 0.406
Q 0.004 0.01 0.102 0.254
Pentium™ is a registered trademark of Intel Corporation
