MK1442-02S Integrated Circuit System, MK1442-02S Datasheet - Page 2

• Manufacturer Part Number: MK1442-02S
• Description: Scsi And Ethernet Clock Source
• Manufacturer: Integrated Circuit System

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.
MDS 1442/3 E
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 •[phone]tel • www.icst.com
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.
Pin Descriptions
Number
10
11
12
13
14
15
16
CPUS1
1
2
3
4
5
6
7
8
9
VDD
GND
24M
40M
20M
X2
X1
KBOUT
CPUS1
2XCPU
CPUS0
14.3M
Name
VDD
GND
GND
VDD
CPU
24M
40M
20M
OE
X2
X1
1
2
3
4
5
6
7
8
Type
TI
TI
O
O
O
O
O
O
O
O
P
P
P
P
I
I
15
14
13
12
11
10
16
9
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.
CPU
14.3M
OE or 14.3M
(MK1442)
CPUS0
2XCPU
VDD
GND
KBOUT
(MK1443)
2
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
4. These selections are not guaranteed to operate at 3V
CPUS1 CPUS0 2XCPU (MHz)
violate Intel’s 0.1% per cycle specification.
M
M
M
SCSI and Ethernet Clock Source
0
0
0
1
1
1
M
M
M
0
1
0
1
0
1
100.00 (note 4)
80.00
33.33
66.67
60.00
50.00
20.00
25.00
8.00
Revision 111500
MK1442/MK1443
50.00 (note 4)
CPU (MHz)
40.00
16.67
33.33
30.00
25.00
10.00
12.50
4.00
Printed 11/15/00