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.
Features
• 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
Block Diagram
VDD
FS0
FS1
FS2
PS
CPU
Clocks
÷2
GND
Output
Buffer
Output
Buffer
2XCPU
CPU
BCLKS
Local
Bus
Clock
Fixed
Clock
Crystal
Oscillator
Output
Buffer
BCLK
X1
14.318 MHz
crystal
X2
Output
Buffer
40.00 (MK1434)
or 24.00 MHz
(MK1432)
Output
Buffer
14.318 MHz
MDS 1432 G
1
Revision 060101
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800 • www.icst.com
MK1432/MK1434
Green PC and Local Bus Clock Source
Pin Assignment
FS2 1
X2 2
X1 3
VDD 4
GND 5
BCLK 6
24M 7
PS 8
16
15
14
13
12
11
10
9
FS1
2XCPU
CPU
VDD
GND
14.3M
FS0
BCLKS
FS2
X2
X1
VDD
GND
BCLK
40M
PS
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
FS1
2XCPU
CPU
VDD
GND
14.3M
FS0
BCLKS
CPU Clock Decoding Table (in MHz)
PS
1
1
1
1
1
1
1
1
0
F S 2 F S 1 F S 0 2XCPU
CPU
0
0
0
16.00
8.00
0
0
1 100.00 note 350.00 note3
0
1
0
80.00
40.00
0
1
1
75.00
37.50
1
0
0
40.00
20.00
1
0
1
50.00
25.00
1
1
0
66.66
33.33
1
1
1
60.00
30.00
X
X
X
33.33
16.67
Local Bus Clock Decoding Table (in MHz)
BCLKS
0
M
1
BCLK (MHz)
25.00
33.33
50.00
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).
Pin Descriptions
1432
1
2
3
4
5
6
7
-
8
9
10
11
12
13
14
15
16
1434
1
2
3
4
5
6
-
7
8
9
10
11
12
13
14
15
16
Name
FS2
X2
X1
VDD
GND
BCLK
24M
40M
PS
BCLKS
FS0
14.3M
GND
VDD
CPU
2XCPU
FS1
Type
I
O
I
P
P
O
O
O
I
TI
I
O
P
P
O
O
I
Description
Select 2 for 2XCPU and CPU frequencies. See table above. Internal Pull-Up.
Crystal connection. Connect to 14.31818 MHz crystal.
Crystal connection. Connect to 14.31818 MHz crystal or clock.
Connect to +5V or 3.3V. Must be same voltage as pin 13.
Connect to ground.
Local Bus Clock output. See table above.
24.00 MHz clock output (MK1432 only).
40.00 MHz clock output (MK1434 only).
Power Saving pin. Smoothly changes CPU to/from 33.33 and 16.67 MHz. IPU.
Local Bus Clock Select pin. See table above.
Select 0 for 2XCPU and CPU frequencies. See table above. Internal Pull-Up.
14.318 MHz Reference Clock Output.
Connect to ground.
Connect to +5V or 3.3V. Must be same voltage as pin 4.
CPU Clock output. See table above for frequencies.
2X CPU Clock output. See table above for frequencies.
Select 1 for 2XCPU and CPU frequencies. See table above. Internal Pull-Up.
Key: TI = Tri-level Input, I = Input, O = output, P = power supply connection
MDS 1432 G
2
Revision 060101
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800 • www.icst.com
MK1432/MK1434
Green PC and Local Bus Clock Source
Electrical Specifications
Parameter
Conditions
Minimum Typical
Maximum
Units
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)
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)
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
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
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.
MDS 1432 G
3
Revision 060101
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800 • www.icst.com
MK1432/MK1434
Green PC and Local Bus Clock Source
Package Outline and Package Dimensions
16 pin SOIC narrow
Inches
Symbol Min
Max
A
0.055 0.070
b
0.013 0.019
c
0.007 0.010
D
0.385 0.400
E
0.150 0.160
H
0.225 0.245
e
.050 BSC
h
0.016
Q
0.004 0.01
Millimeters
Min
Max
1.397 1.778
0.330 0.483
0.191 0.254
9.779 10.160
3.810 4.064
5.715 6.223
1.27 BSC
0.406
0.102 0.254
E
H
h x 45°
D
Q
e
b
c
A
Ordering Information
Part/Order Number
MK1432S
MK1434S
MK1432STR
MK1434STR
Marking
MK1432S
MK1434S
MK1432S
MK1434S
Fixed Output Clock Frequency
24 MHz
40 MHz
-
-
Package
16 pin SOIC
16 pin SOIC
Add Tape & Reel
Add Tape & Reel
Temperature
0-70°C
0-70°C
-
-
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.
Pentium™ is a registered trademark of Intel Corporation
MDS 1432 G
4
Revision 060101
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800 • www.icst.com
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