ICST MK2014A, MK2014ATR Datasheet
MK2014A
ICRO
C
LOCK
Description
The MK2014A is the ideal way to generate clocks
for Fast Ethernet cards or systems. It provides
20MHz and 25MHz clocks from an inexpensive
14.31818 MHz crystal or clock. In an 8 pin SOIC,
the MK2014A can save component count, board
space, and cost over surface mount crystals and
oscillators, and increase reliability by eliminating
mechanical devices from the board.
The MK2014A is a functionally identical update
of the MK2014 and should be used in all designs.
The only change is in crystal load capacitance as
stated on page 2.
MicroClock offers many other clocks for
computers and computer peripherals. Consult your
MicroClock representative when you need to
remove crystals and oscillators from your board.
Fast Ethernet Clock Source
Features
• Packaged in 8 pin SOIC
• Input crystal or clock frequency of 14.318 MHz
• Lowest jitter in the industry reliably clocks
sensitive Ethernet devices.
• Output clock frequencies of 20.00 MHz and
25.00 MHz
• Zero ppm synthesis error in the output clocks
• Full CMOS outputs with 25mA drive capability
at TTL levels
• 3.3V or 5V±10% supply voltage
• Advanced, low power CMOS process
Block Diagram
14.31818 MHz
crystal or clock
X1
X2
VDD GND
2
Crystal
Oscillator
• Insensitive to input clock duty cycle
Clock Synthesis
and Control
Circuitry
Output
Buffer
Output
Buffer
Output
Buffer
20 MHz
25 MHz
14.318 MHz
MDS 2014A B 1 Revision 121598 Printed 11/15/00
MicroClock Division of ICS • 525 Race Street • San Jose • CA • 95126•(408)295-9800tel•(408)295-9818fax
MK2014A
Pin Assignment
X1/ICLK
VDD
GND
25M
1 8
2
3
4
ICRO
8 pin SOIC
C
LOCK
7
6
5
Suggested Layout
X2
14M
20M
GND
V
0.1µF
G
33Ω (optional)
Fast Ethernet Clock Source
14.3 MHz in
(crystal caps not
shown)
Pin 1
2
3
4
8
7
33Ω (optional)
6
5
33Ω (optional)
14.3MHz
out
20MHz
out
Pin Descriptions
Number Name Type Description
1 X1/ICLK XI Crystal Connection. Connect to a 14.31818 MHz crystal or clock.
2 VDD P Connect to +5V.
3 GND P Connect to ground.
4 25M O 25.000 MHz clock output.
5 GND P Connect to ground.
6 20M O 20.000 MHz clock output.
7 14M O 14.31818 MHz buffered crystal clock output.
8 X2 XO Crystal Connection to a 14.31818 MHz crystal, or leave unconnected for clock input.
Key: I = Input, O = output, P = power supply connection
25MHz out
External Components/Crystal Selection
A minimum number of external components are required for proper oscillation. A decoupling capacitor of
0.1 µF should be connected between VDD and GND on pins 2 and 3, and 33 Ω terminating resistors
should be used on clock outputs with traces longer than 1 inch. For a clock input, connect to X1 and leave
X2 unconnected. For a crystal input, a parallel resonant 14.31818 MHz crystal is recommended. The
frequency accuracy of the crystal should be 30 ppm or better. External capacitors from each of the X1 and
X2 pins to ground should be added with a value in pF equal to (CL-13)*2, where CL is the crystal load
capacitance in pF. So for a crystal with load capacitance of 16 pF, 6 pF capacitors should be used. [Note
that the MK2014S required crystal load capacitors of (CL-4)*2.]
MDS 2014A B 2 Revision 121598 Printed 11/15/00
MicroClock Division of ICS • 525 Race Street • San Jose • CA • 95126•(408)295-9800tel•(408)295-9818fax
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