ICS281

MDS 281 C

1

Revision 062205

Integrated Circuit Systems, Inc.

Triple PLL Field Prog. Spread Spectrum Clock Synthesizer

PRELIMINARY INFORMATION

Description

The ICS281 field programmable spread spectrum

clock synthesizer generates up to three high-quality,

high-frequency clock outputs including multiple

reference clocks from a low-frequency crystal input. It

is designed to replace crystals, crystal oscillators and

stand alone spread spectrum devices in most

electronic systems.

and outputs, the ICS281 contains a One-Time

Programmable (OTP) ROM for field programmability.

Programming features include input/output

frequencies, spread spectrum amount and eight

selectable configuration registers.

Using Phase-Locked Loop (PLL) techniques, the

device runs from a standard fundamental mode,

inexpensive crystal, or clock. It can replace multiple

crystals and oscillators, saving board space and cost.

The ICS281 is also available in factory programmed

custom versions for high-volume applications.

Features

Block Diagram

Crystal

Oscillator

GND

3

3

VDD

PDTS

PLL2

PLL3

Divide

Logic

and

Output

Enable

Control

S2:S0

CLK1

CLK3

CLK2

3

OTP

ROM

with PLL

Values

X2

Crystal or

clock input

External capacitors

are required with a crystal input.

X1/ICLK

PLL1 with

Spread

Spectrum

VDDO