ICS291

MDS 291 C

1

Revision 062205

Integrated Circuit Systems, Inc.

Triple PLL Field Prog. Spread Spectrum Clock Synthesizer

PRELIMINARY INFORMATION

Description

The ICS291 field programmable spread spectrum clock

synthesizer generates up to six 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 ICS291 contains a One-Time

Programmable (OTP) ROM for field programmability.

Programming features include input/output

frequencies, spread spectrum amount, eight selectable

configuration registers and up to two sets of three

low-skew outputs.

Each of the two output groups are powered by a

separate VDDO voltage. VDDO may vary from 1.8 V to

VDD.

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 ICS291 is also available in factory programmed

custom versions for high-volume applications.

Features

each bank of 3 outputs

Block Diagram

Crystal

Oscillator

GND

3

3

VDD

PDTS

PLL2

PLL3

Divide

Logic

and

Output

Enable

Control

S2:S0

CLK1

CLK6

CLK5

CLK4

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

VDDO1

VDDO2