2

ICS9120-49

Pin Configuration

Pin Descriptions for ICS9120-49

8-Pin SOIC

External Components/Crystal Selection

The ICS9120-49 incorporates a crystal oscillator circuit de-signed

to provide 50% duty cycle over a range of operating conditions,

including the addition of external crystal load ca-pacitors to pins

X1 and X2. A parallel resonant 16.9344 MHz, 12pF load crystal is

recommended. A series resonant crystal or a parallel resonant

crystal specifying a different load can be used, but either will

result in frequencies which are slightly (up to 0.06%) different

from the ideal.

The crystal load capacitance can be increased by adding a capacitor

to each of the X1 and X2 pins and ground. This enables the use of

a crystal specifying a load greater than 12pF without changing the

output frequency.

Duty cycle is also maintained when using an external clock source

(connected to X1, X2 left unconnected) as long as the external

clock has good duty cycle.

PIN

NUMBER

PIN

NAME

TYPE

DESCRIPTION

1

X1

Input

Crystal or external clock source. Has feedback bias for crystal.

2

VDD

Power

+Power supply input.

3

GND

Power

Ground return for Pin 2.

4

CLK3

Output

33.8688 MHz target output clock.

5

CLK2

Output

22.5792 MHz target output clock.

6

CLK4

Output

67.7376 MHz target output clock.

7

CLK1

Output

16.9344 MHz reference clock buffered output.

8

X2

Output

Crystal output drive (leave this pin unconnected when using an external clock).