MK2014A

Fast Ethernet Clock Source

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

I C R O

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.

Pin Descriptions

Key: I = Input, O = output, P = power supply connection

Pin Assignment

14.3 MHz in

(crystal caps not

shown)

Pin 1

2

3

5

6

7

0.1µF

25MHz out

G

V

33

Ω (optional)

Suggested Layout

4

8

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.]

33

Ω (optional)

14.3MHz

out

1

8

2

3

4

7

6

5

X1/ICLK

14M

GND

X2

VDD

20M

GND

8 pin SOIC

25M

33

Ω (optional)

20MHz

out