MK1442/MK1443
SCSI and Ethernet Clock Source
MDS 1442/3 F 1 Revision 101001
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
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.
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
• 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
14.318 MHz
(MK1443 only)
Output
Buffer
MK1442/MK1443
SCSI and Ethernet Clock Source
MDS 1442/3 F 2 Revision 101001
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 •(408)297-1201tel • www.icst.com
Number Name Type Description
1CPUS1 TI Select 1 for 2XCPU and CPU frequencies. See Table above, note 5 below.
2X2 O
Crystal connection. Connect to 14.318 MHz crystal, or leave unconnected for clock input.
3X1 I Crystal connection. Connect to 14.318 MHz crystal, or drive with a 14.318MHz clock.
4VDD P Connect to +5V or 3.3V. Must be same voltage as pin 13.
5GND P Connect to ground.
6 24M O 24.00 MHz floppy (or super I/O) clock output.
740M O 40.00 MHz clock output
8 20M O 20.000 MHz Ethernet clock output
9KBOUT 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
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.
(MK1443)(MK1442)
16 pin (150 mil) SOIC
MK1442/MK1443
SCSI and Ethernet Clock Source
MDS 1442/3 F 3 Revision 101001
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 kΩ
Input Capacitance 7 pF
Frequency Accuracy of 20.000 MHz clock 0-70°C, 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 µs
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 ICS.
MK1442/MK1443
SCSI and Ethernet Clock Source
MDS 1442/3 F 4 Revision 101001
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, 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
b
D
E H
e
QcA
h x 45°
Package Outline and Package Dimensions
Ordering Information
Part/Order Number Marking Keyboard frequency Package Temperature
MK1442-02S MK1442-02S 8 MHz 16 pin SOIC 0-70°C
MK1442-03S MK1442-03S 16 MHz 16 pin SOIC 0-70°C
MK1443-01S MK1443-01S 12 MHz 16 pin SOIC 0-70°C
MK1443-02S MK1443-02S 8 MHz 16 pin SOIC 0-70°C
MK144x-0xSTR MK144x-0xS x Add Tape & Reel 0-70°C
16 pin SOIC narrow
Inches
Inches
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
h 0.016 0.406
Q 0.004 0.01 0.102 0.254