ICS7151

MDS 7151 E

1

Revision 012306

Integrated Circuit Systems, Inc.

Spread Spectrum Clock Generator

Description

The ICS7151-10, -20, -40, and -50 are clock

generators for EMI (Electro Magnetic Interference)

reduction (see below for frequency ranges and

multiplier ratios). Spectral peaks can be attenuated by

slightly modulating the oscillation frequency. Both down

and center spread profiles are selectable. Down spread

maintains an average frequency less than an unspread

clock, and will not exceed the maximum frequency of

an unspread clock.

Features

33.4 MHz, 33.3 to 66.7 MHz, 66.6 to 133.4 MHz

±1.5% center spread; -1.0%, -3.0% down spread)

Block Diagram

Product Lineup

Product

Input Frequency Range

Multiplier Ratio

Output Frequency Range

ICS7151M-10, ICS7151MI-10

16.5 MHz to 33.4 MHz

X1

16.5 MHz to 33.4 MHz

ICS7151M-20, ICS7151MI-20

16.5 MHz to 33.4 MHz

X2

33.3 MHz to 66.7 MHz

ICS7151M-40, ICS7151MI-40

16.5 MHz to 33.4 MHz

X4

66.6 MHz to 133.4 MHz

ICS7151M-50, ICS7151MI-50

16.5 MHz to 33.4 MHz

X1/2

8.3 MHz to 16.7 MHz

PLL Clock

Synthesis

and Spread

Spectrum

Circuitry

S1:0

ENS

CKOUT

2

GND

VDD

Clock Buffer/

Crystal

Ocsillator

XIN

XOUT

External caps required with crystal for

accurate tuning of the clock