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TRIPLE PLL FIELD PROG. SPREAD SPECTRUM CLOCK SYNTHESIZER

ICS291

IDT™ / ICS™ TRIPLE PLL FIELD PROG. SPREAD SPECTRUM CLOCK SYNTHESIZER 1

ICS291

REV D 061306

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.

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