ICST MK2011STR, MK2011S Datasheet
MK2011
ICRO
C
LOCK
Description
The MK2011 is the ideal way to generate clocks
for Fast Ethernet cards or systems. It provides
20MHz, 25MHz, and 50MHz clocks. In an 8 pin
SOIC, the MK2011 can save component count,
board space, and cost over surface mount crystals
and oscillators, and increase reliability by
eliminating two or three mechanical devices from
the board.
MicroClock offers many other clocks for
computers and computer peripherals. Consult
MicroClock 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 20.00 MHz
• Lowest jitter in the industry reliably clocks
sensitive Ethernet devices.
• Output clock frequencies of 20.00 MHz,
25.00 MHz, and 50.00 MHz
• 25mA drive capability at TTL levels
• 3.3V or 5V±10% supply voltage
• Advanced, low power CMOS process
• Insensitive to input clock duty cycle
Block Diagram
VDD GND
Output
PLL
20.00 MHz
xtal or clock
X1
Crystal
Oscillator
X2
MDS 2011 B 1 Revision 120597 Printed 11/15/00
MicroClock Division of ICS•1271 Parkmoor Ave.•San Jose•CA•95126•(408)295-9800tel•(408)295-9818fax
Clock Synthesis
Circuitry
Buffer
Output
Buffer
Output
Buffer
50 MHz
25 MHz
20 MHz
MK2011
Pin Assignment
X1/ICLK
VDD
GND
25M
1 8
2
3
4
ICRO
8 pin SOIC
C
LOCK
7
6
5
Suggested Layout
X2
20M
GND
50M
V
0.1µF
G
33Ω (optional)
Fast Ethernet Clock Source
20.00 MHz in
(crystal caps not
shown)
Pin 1
2
3
4
8
7
33Ω (optional)
6
5
33Ω (optional)
20MHz
out
25MHz out 50MHz out
Pin Descriptions
Number Name Type Description
1 X1/ICLK I Crystal Connection. Connect to a 20.000 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 50M O 50.000 MHz clock output.
6 GND P Connect to ground.
7 20M O 20.000 MHz buffered crystal clock output.
8 X2 O Crystal Connection to a 20.000 MHz crystal, or leave unconnected for clock input.
Key: I = Input, O = output, P = power supply connection
External Components/Crystal Selection
A minimum number of external components are required for proper oscillation. For a crystal input, one
22pF load capacitor should be connected to each of the X1 and X2 pins and ground, and a parallel
resonant 20.000 MHz, 16pF load, crystal is recommended. The frequency tolerance of the crystal should
be 50ppm or better. For a clock input, connect to X1 and leave X2 unconnected. A decoupling capacitor of
0.1µF should be connected between VDD and GND on pins 2 and 3, and 33Ω terminating resistors
should be used on clock outputs with traces longer than 1 inch.
MDS 2011 B 2 Revision 120597 Printed 11/15/00
MicroClock Division of ICS•1271 Parkmoor Ave.•San Jose•CA•95126•(408)295-9800tel•(408)295-9818fax
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