Tel :

+44 118 979 1238

Fax :

+44 118 979 1283

email :

info@actcrystals.com

EMI Reduction Data

Main mode: EMI reduction:

Total spread % x frequency(fo)

3rd Harmonic: EMI reduction:

5th Harmonic: EMI reduction:

For quotations or further information please contact us at:

3 The Business Centre, Molly Millars Lane, Wokingham, Berks, RG41 2EY, UK

http://www.actcrystals.com

Issue:4 M6

Date:26/10/05

dB

0.12

10Log

(

Total spread % x frequency(fo)x5

)

ISO9001: 2000 Registered

101.875000

99.375000

100.625000

10Log

(

+1.875%

-30000ppm

0ppm

-15000ppm

+15000ppm

3.75

-3.75%

0%

-1.875%

96.250000

100.000000

98.125000

96.500000

100.000000

98.250000

101.750000

101.250000

3.5

-3.5%

0%

-1.75%

+1.75%

-35000ppm

0ppm

-17500

+17500

+1.5%

-30000ppm

0ppm

-15000ppm

+15000ppm

3.0**

-3.0%

0%

-1.5%

97.500000

100.000000

98.750000

99.000000

100.000000

99.500000

100.500000

101.000000

2.5

-2.5%

0%

-1.25%

+1.25%

-25000

0ppm

-12500

+12500

+1.0%

-20000

0ppm

-10000

+10000

2.0

-2.0%

0%

-1.0%

98.000000

100.000000

-99.000000

Principle of Spread Spectrum (continued from page 2

(

Total spread % x frequency(fo)x3

)

)

dB

+2500ppm

ACT9200SSCL

99.500000

100.000000

99.750000

100.250000

Up Range

+0.25%

Down Range

Up Range

Spread Spectrum Clock (SSC), the mode energy of a spread spectrum clock is spread over a

wider bandwidth, resulting from the frequency modulation technique. The modulation carrier

frequency is in the KHz range which makes the modulation process transparent to the oscillator

frequency. The controlled modulation process can be on all of one side of the nominal frequency

(DOWN SPREAD) or equally spread either side of the nominal frequency (CENTRE SPREAD) . If

OVER-CLOCKING is a problem to the system then the down spread is preferred.

Down Spread

Centre Spread

Instantaneous Frequencies (100MHz Nominal Frequency)

Down Range

1.25

-5000ppm

99.250000

-0.5%

-0.75%

0%

-0.25%

Total Spread

%

0.5

Max

0.75

Min

Max

Min

0%

-0.375

100.000000

99.625000

0ppm

-2500ppm

+0.375

-7500

0ppm

-3750

-3750

100.375000

-1.25%

0%

-0.625%

+0.625

98.750000

100.000000

0.12

-12500

0ppm

-6250

+12650

0.12

dB

10Log

Page 3 of 5