• Provides exact frequency Ethernet and SCSI clocks
• 5V or 3.3V (up to 80MHz) operation
• Output clock frequencies up to 100 MHz
• Pentium™ Processor compatible timing
• 486 compatible smooth frequency transitions
• Seven or eight output clocks
• Compatible with X86 and 680X0 CPUs
• Skew controlled 2X and 1X CPU to within 250ps
• Packaged in 16 pin skinny SOIC or PDIP
• Duty cycle of 47.5/52.5 up to 66.66 MHz
• Duty cycle of 45/55 up to 100 MHz
• Total of 15 different selectable CPU frequencies
• Tri-state outputs for board level testing
• 25mA drive capability at TTL levels
• Keyboard frequencies of 12MHz (-01),
8MHz (-02), or 16MHz (-03)
• Advanced, low power CMOS process
• MK1442 - output enable
• MK1443 - two 14.318 MHz outputs
Block Diagram
VDD
GND
CPUS0
CPUS1
Output
Buffer
2XCPU
CPU
8.00, 12.00,
or 16.00 MHz
24.00 MHz
40.000 MHz
20.000 MHz
14.318 MHz
(MK1443 only)
14.318 MHz
÷2
Clock Synthesis
and Control
Circuitry
Output
Buffer
Output
Buffer
Output
Buffer
Output
Buffer
14.318 MHz
crystal
X1
Output
Buffer
Output
Buffer
Output
Buffer
Crystal
Oscillator
X2
OE (all outputs, MK1442 only)
1
Revision 111500
Printed 11/15/00
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 •(408)297-1201tel • www.icst.com
MDS 1442/3 E
MK1442/MK1443
SCSI and Ethernet Clock Source
Pin Assignment
CPUS1
X2
X1
VDD
GND
24M
40M
20M
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
CPUS0
2XCPU
CPU
VDD
GND
14.3M
OE or 14.3M
(MK1442)
(MK1443)
CPU Clock Decoding
CPUS1 CPUS0 2XCPU (MHz)
CPU (MHz)
0
0
8.00
4.00
0
M
80.00
40.00
0
1
33.33
16.67
M
0
100.00 (note 4)
50.00 (note 4)
M
M
66.67
33.33
M
1
60.00
30.00
1
0
50.00
25.00
1
M
20.00
10.00
1
1
25.00
12.50
Notes:
1. M = mid point (input is left floating. See note 5 below)
2. Actual frequencies are within 0.05% of those shown.
3. Transitions between mean frequencies are smooth, and do not
violate Intel’s 0.1% per cycle specification.
4. These selections are not guaranteed to operate at 3V
KBOUT
Pin Descriptions
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Name
CPUS1
X2
X1
VDD
GND
24M
40M
20M
KBOUT
OE
14.3M
GND
VDD
CPU
2XCPU
CPUS0
Type
TI
O
I
P
P
O
O
O
O
I
O
P
P
O
O
TI
Description
Select 1 for 2XCPU and CPU frequencies. See Table above, note 5 below.
Crystal connection. Connect to 14.318 MHz crystal, or leave unconnected for clock input.
Crystal connection. Connect to 14.318 MHz crystal, or drive with a 14.318MHz clock.
Connect to +5V or 3.3V. Must be same voltage as pin 13.
Connect to ground.
24.00 MHz floppy (or super I/O) clock output.
40.00 MHz clock output
20.000 MHz Ethernet clock output
Keyboard clock. 12.00 MHz on -01, 8.00 MHz on -02, 16.00 MHz on -03 version.
Output Enable on 1442. Tri-states all clock outputs when this input is low. Internal pull-up.
14.318 MHz system clock output.
Connect to ground.
Connect to +5V or 3.3V. Must be same voltage as pin 4.
CPU output. See Table above. Rising edge is within 250ps of 2XCPU.
2XCPU output. See Table above. Rising edge is within 250ps of CPU.
Select 0 for 2XCPU and CPU frequencies. See Table above, note 5 below.
Key: I = Input, TI = three level input, O = output, P = power supply connection
Note 5:
The TI inputs are internally held at mid-level, so they cannot drift high or low.
Crystal and Capacitor Selection for Ethernet Accuracy
The MK1442/3 requires external crystals between the X1 and X2 pins and ground, as shown on the block
diagram on page 1. For an accurate Ethernet frequency of 20.000 MHz, a 14.31818 MHz ±50 ppm,
parallel resonant crystal with a load capacitance of 16pF is recommended, along with 22 pF ±5% (NPO
dielectric) chip capacitors. If the 20 MHz output is not used for Ethernet, any 22 pF capacitors will work.
2
Revision 111500
Printed 11/15/00
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 •(408)297-1201tel • www.icst.com
MDS 1442/3 E
MK1442/MK1443
SCSI and Ethernet Clock Source
Electrical Specifications
Parameter
Supply voltage, VDD
Inputs and Clock Outputs
Ambient Operating Temperature
Soldering Temperature
Storage Temperature
Operating Voltage, VDD
Input High Voltage, VIH
Input Low Voltage, VIL
Input High Voltage, VIH
Input Mid-level Voltage
Input Low Voltage, VIL
Output High Voltage, VOH
Output High Voltage, VOH
Output Low Voltage, VOL
Input High Voltage, VIH
Input Low Voltage, VIL
Output High Voltage, VOH
Output Low Voltage, VOL
Operating Supply Current, IDD
Short Circuit Current
On-Chip Pull-up Resistor
Input Capacitance
Frequency Accuracy of 20.000 MHz clock
Conditions
Referenced to GND
Referenced to GND
Max of 20 seconds
-65
3.0
2.0
Minimum
Typical
Maximum
7
VDD+0.5
70
260
150
5.5
Units
V
V
°C
°C
°C
V
V
V
V
V
V
V
V
V
V
V
V
V
mA
mA
kΩ
pF
ppm
ABSOLUTE MAXIMUM RATINGS (note 1)
-0.5
0
DC CHARACTERISTICS (VDD = 5V unless noted)
OE (pin 10)
OE (pin 10)
0.8
CPUS0,1 (pins 1,16)
VDD-0.5
CPUS0,1 (pins 1,16)
Leave pin unconnected or tri-stated
CPUS0,1 (pins 1,16)
0.5
IOH=-4mA
VDD-0.4
IOH=-25mA
2.4
IOL=25mA
0.4
VDD=3.3V, OE pin
1.9
VDD=3.3V, OE pin
0.4
VDD=3.3V, IOH=-8mA
2.4
VDD=3.3V, IOL=8mA
0.4
No Load, 80 MHz
35
Each output
±100
250
7
0-70°C, note 2
-1
1
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, CPU and 2XCPU
1.5V, up to 67MHz
47.5
49 to 51
52.5
%
Output Clock Duty Cycle
At 1.5V
45
49 to 51
55
%
Cycle to Cycle Jitter
50-80 MHz clocks
250
ps
Skew of 2XCPU with respect to CPU
Rising edges at 1.5V
-250
0
250
ps
Transition time, 8MHz to 100MHz
VDD=3.3 or 5V
4
ms
Transition time, 100MHz to 8MHz
VDD=3.3 or 5V
2.5
ms
Output Enable Time, OE high to output on
VDD=3.3 or 5V
50
ns
Output Disable Time, OE low to tri-state
VDD=3.3 or 5V
3
µs
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. Provided proper crystal and capacitor components are used - consult MicroClock.
3
Revision 111500
Printed 11/15/00
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 •(408)297-1201tel • www.icst.com
MDS 1442/3 E
MK1442/MK1443
SCSI and Ethernet Clock Source
Package Outline and Package Dimensions
16 pin SOIC narrow
Symbol
A
b
c
D
E
H
e
h
Q
Inches
Min
Max
0.055 0.070
0.013 0.019
0.007 0.010
0.385 0.400
0.150 0.160
0.225 0.245
.050 BSC
0.016
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
D
Q
e
c
h x 45°
A
b
Ordering Information
Part/Order Number
MK1442-01S
MK1442-02S
MK1442-03S
MK1443-01S
MK1443-02S
MK1443-03S
MK144x-0xSTR
Marking
MK1442-01S
MK1442-02S
MK1442-03S
MK1443-01S
MK1443-02S
MK1443-03S
MK144x-0xS
Keyboard frequency
12 MHz
8 MHz
16 MHz
12 MHz
8 MHz
16 MHz
x
Package
16 pin SOIC
16 pin SOIC
16 pin SOIC
16 pin SOIC
16 pin SOIC
16 pin SOIC
Add Tape & Reel
Temperature
0-70°C
0-70°C
0-70°C
0-70°C
0-70°C
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
4
Revision 111500
Printed 11/15/00
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 •(408)297-1201tel • www.icst.com
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