MK1442/MK1443
SCSI and Ethernet Clock Source
MDS 1442/3 E
1
Revision 111500
Printed 11/15/00
Integrated Circuit Systems, Inc. 525 Race Street San Jose CA 95126 (408)297-1201tel www.icst.com
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 PentiumTM 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.
Crystal
Oscillator
VDD
GND
X1
X2
Clock Synthesis
and Control
Circuitry
2XCPU
14.318 MHz
40.000 MHz
24.00 MHz
8.00, 12.00,
or 16.00 MHz
Output
Buffer
CPUS0
CPUS1
14.318 MHz
crystal
Block Diagram
Description
Features
Output
Buffer
Output
Buffer
Output
Buffer
Output
Buffer
Output
Buffer
Output
Buffer
2
CPU
OE (all outputs, MK1442 only)
20.000 MHz
Provides exact frequency Ethernet and SCSI clocks
5V or 3.3V (up to 80MHz) operation
Output clock frequencies up to 100 MHz
PentiumTM 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
14.318 MHz
(MK1443 only)
Output
Buffer
MK1442/MK1443
SCSI and Ethernet Clock Source
MDS 1442/3 E
2
Revision 111500
Printed 11/15/00
Integrated Circuit Systems, Inc. 525 Race Street San Jose CA 95126 (408)297-1201tel www.icst.com
Number
Name
Type
Description
1
CPUS1
TI
Select 1 for 2XCPU and CPU frequencies. See Table above, note 5 below.
2
X2
O
Crystal connection. Connect to 14.318 MHz crystal, or leave unconnected for clock input.
3
X1
I
Crystal connection. Connect to 14.318 MHz crystal, or drive with a 14.318MHz clock.
4
VDD
P
Connect to +5V or 3.3V. Must be same voltage as pin 13.
5
GND
P
Connect to ground.
6
24M
O
24.00 MHz floppy (or super I/O) clock output.
7
40M
O
40.00 MHz clock output
8
20M
O
20.000 MHz Ethernet clock output
9
KBOUT
O
Keyboard clock. 12.00 MHz on -01, 8.00 MHz on -02, 16.00 MHz on -03 version.
10
OE
I
Output Enable on 1442. Tri-states all clock outputs when this input is low. Internal pull-up.
11
14.3M
O
14.318 MHz system clock output.
12
GND
P
Connect to ground.
13
VDD
P
Connect to +5V or 3.3V. Must be same voltage as pin 4.
14
CPU
O
CPU output. See Table above. Rising edge is within 250ps of 2XCPU.
15
2XCPU
O
2XCPU output. See Table above. Rising edge is within 250ps of CPU.
16
CPUS0
TI
Select 0 for 2XCPU and CPU frequencies. See Table above, note 5 below.
Pin Descriptions
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
CPU Clock Decoding
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
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.
1
8
9
16
2
3
4
5
6
7
10
11
12
13
14
15
CPUS0
14.3M
CPU
2XCPU
VDD
GND
CPUS1
X2
40M
24M
VDD
GND
X1
20M
KBOUT
OE or 14.3M
(MK1442) (MK1443)
Pin Assignment
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.
MK1442/MK1443
SCSI and Ethernet Clock Source
MDS 1442/3 E
3
Revision 111500
Printed 11/15/00
Integrated Circuit Systems, Inc. 525 Race Street San Jose CA 95126 (408)297-1201tel www.icst.com
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
OE (pin 10)
2.0
V
Input Low Voltage, VIL
OE (pin 10)
0.8
V
Input High Voltage, VIH
CPUS0,1 (pins 1,16)
VDD-0.5
V
Input Mid-level Voltage
CPUS0,1 (pins 1,16)
Leave pin unconnected or tri-stated
Leave pin unconnected or tri-stated
Leave pin unconnected or tri-stated
V
Input Low Voltage, VIL
CPUS0,1 (pins 1,16)
0.5
V
Output High Voltage, VOH
IOH=-4mA
VDD-0.4
V
Output High Voltage, VOH
IOH=-25mA
2.4
V
Output Low Voltage, VOL
IOL=25mA
0.4
V
Input High Voltage, VIH
VDD=3.3V, OE pin
1.9
V
Input Low Voltage, VIL
VDD=3.3V, OE pin
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, 80 MHz
35
mA
Short Circuit Current
Each output
100
mA
On-Chip Pull-up Resistor
250
k
Input Capacitance
7
pF
Frequency Accuracy of 20.000 MHz clock
0-70C, note 2
-1
1
ppm
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, 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
s
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. Provided proper crystal and capacitor components are used - consult MicroClock.
MK1442/MK1443
SCSI and Ethernet Clock Source
MDS 1442/3 E
4
Revision 111500
Printed 11/15/00
Integrated Circuit Systems, Inc. 525 Race Street San Jose CA 95126 (408)297-1201tel 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.
PentiumTM is a registered trademark of Intel Corporation
b
D
E
H
e
Q
c
A
h x 45
Package Outline and Package Dimensions
Ordering Information
Part/Order Number
Marking
Keyboard frequency
Package
Temperature
MK1442-01S
MK1442-01S
12 MHz
16 pin SOIC
0-70C
MK1442-02S
MK1442-02S
8 MHz
16 pin SOIC
0-70C
MK1442-03S
MK1442-03S
16 MHz
16 pin SOIC
0-70C
MK1443-01S
MK1443-01S
12 MHz
16 pin SOIC
0-70C
MK1443-02S
MK1443-02S
8 MHz
16 pin SOIC
0-70C
MK1443-03S
MK1443-03S
16 MHz
16 pin SOIC
0-70C
MK144x-0xSTR
MK144x-0xS
x
Add Tape & Reel
0-70C
16 pin SOIC narrow
Inches
Inches
Millimeters
Millimeters
Symbol
Min
Max
Min
Max
A
0.055
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
E
0.150
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
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