MK1442/MK1443
SCSI and Ethernet Clock Source
Description
The MK1442/3 are the ideal way to generate clocks for
desktop computer motherboards and LAN
workstations. 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 2XCPU, CPU,
floppy controller, keyboard, system, SCSI and
Ethernet clocks. The MK1442/3 are perfect for new
Pentium™ Processor, PCI bus and 486 systems. The
devices can operate at 5V or 3.3V up to and including
80MHz on the CPU clock.
The devices are identical except the MK1442 has an
Output Enable (OE) pin that tri-states all outputs when
taken low, and the MK1443 has an extra 14.318 MHz
clock.
Features
• 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
Output
Buffer
÷2
Output
Buffer
Output
Buffer
Output
Buffer
Output
Buffer
14.318 MHz
crystal
X1
Crystal
Oscillator
X2
Output
Buffer
Output
Buffer
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
CPUS0
CPUS1
Clock Synthesis
and Control Circuitry
OE (all outputs, MK1442 only)
MDS 1442/3 F
1
Revision 101001
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 •(408)297-1201tel • www.icst.com
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)
KBOUT
16 pin (150 mil) SOIC
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
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
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.
MDS 1442/3 F
2
Revision 101001
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 •(408)297-1201tel • www.icst.com
MK1442/MK1443
SCSI and Ethernet Clock Source
Electrical Specifications
Parameter
ABSOLUTE MAXIMUM RATINGS (note 1)
Supply voltage, VDD
Inputs and Clock Outputs
Ambient Operating Temperature
Soldering Temperature
Storage Temperature
DC CHARACTERISTICS (VDD = 5V unless noted)
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
Input Frequency
Output Clock Rise Time
Output Clock Fall Time
Output Clock Duty Cycle, CPU and 2XCPU
Output Clock Duty Cycle
Cycle to Cycle Jitter
Skew of 2XCPU with respect to CPU
Transition time, 8MHz to 100MHz
Transition time, 100MHz to 8MHz
Output Enable Time, OE high to output on
Output Disable Time, OE low to tri-state
0.8 to 2.0V
2.0 to 0.8V
1.5V, up to 67MHz
At 1.5V
50-80 MHz clocks
Rising edges at 1.5V
VDD=3.3 or 5V
VDD=3.3 or 5V
VDD=3.3 or 5V
VDD=3.3 or 5V
-250
0
4
2.5
50
3
47.5
45
49 to 51
49 to 51
0-70°C, note 2
-1
14.31818
1.5
1.5
52.5
55
250
250
AC CHARACTERISTICS (VDD = 5V unless noted)
MHz
ns
ns
%
%
ps
ps
ms
ms
ns
µs
OE (pin 10)
OE (pin 10)
CPUS0,1 (pins 1,16)
CPUS0,1 (pins 1,16)
CPUS0,1 (pins 1,16)
IOH=-4mA
IOH=-25mA
IOL=25mA
VDD=3.3V, OE pin
VDD=3.3V, OE pin
VDD=3.3V, IOH=-8mA
VDD=3.3V, IOL=8mA
No Load, 80 MHz
Each output
35
±100
250
7
1
2.4
0.4
1.9
0.4
VDD-0.4
2.4
0.4
VDD-0.5
Leave pin unconnected or tri-stated
0.5
3.0
2.0
0.8
5.5
V
V
V
V
V
V
V
V
V
V
V
V
V
mA
mA
kΩ
pF
ppm
Max of 20 seconds
-65
Referenced to GND
Referenced to GND
-0.5
0
7
VDD+0.5
70
260
150
V
V
°C
°C
°C
Conditions
Minimum
Typical
Maximum
Units
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 ICS.
MDS 1442/3 F
3
Revision 101001
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 •(408)297-1201tel • www.icst.com
MK1442/MK1443
SCSI and Ethernet 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
MK1442-02S
MK1442-03S
MK1443-01S
MK1443-02S
MK144x-0xSTR
Marking
MK1442-02S
MK1442-03S
MK1443-01S
MK1443-02S
MK144x-0xS
Keyboard frequency
8 MHz
16 MHz
12 MHz
8 MHz
x
Package
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
While the information presented herein has been checked for both accuracy and reliability, ICS 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 ICS. ICS reserves the right to change any circuitry or
specifications without notice. ICS does not authorize or warrant any ICS product for use in life support devices or critical
medical instruments.
Pentium™ is a registered trademark of Intel Corporation
MDS 1442/3 F
4
Revision 101001
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 •(408)297-1201tel • www.icst.com
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