ACT9200SSCL Datasheet, PDF (3/5 Pages) Advanced Crystal Technology – miniature, low profile SMD

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ACT9200SSCL
Principle of Spread Spectrum (continued from page 2
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.
Instantaneous Frequencies (100MHz Nominal Frequency)
Total Spread
%
Down Spread
Min
Max
Down Range
Up Range
-0.5%
0%
0.5
-5000ppm
0ppm
99.500000
100.000000
-0.75%
0%
0.75
-7500
0ppm
99.250000
100.000000
-1.25%
0%
1.25
-12500
0ppm
98.750000
100.000000
-2.0%
0%
2.0
-20000
0ppm
98.000000
100.000000
-2.5%
0%
2.5
-25000
0ppm
99.000000
100.000000
-3.0%
0%
3.0**
-30000ppm
0ppm
97.500000
100.000000
-3.5%
0%
3.5
-35000ppm
0ppm
96.500000
100.000000
-3.75%
0%
3.75
-30000ppm
0ppm
96.250000
100.000000
Centre Spread
Min
Max
Down Range
Up Range
-0.25%
+0.25%
-2500ppm
+2500ppm
99.750000
100.250000
-0.375
+0.375
-3750
-3750
99.625000
100.375000
-0.625%
+0.625
-6250
+12650
99.375000
100.625000
-1.0%
+1.0%
-10000
+10000
-99.000000
101.000000
-1.25%
+1.25%
-12500
+12500
99.500000
100.500000
-1.5%
+1.5%
-15000ppm
+15000ppm
98.750000
101.250000
-1.75%
+1.75%
-17500
+17500
98.250000
101.750000
-1.875%
+1.875%
-15000ppm
+15000ppm
98.125000
101.875000
EMI Reduction Data
Main mode: EMI reduction:
3rd Harmonic: EMI reduction:
5th Harmonic: EMI reduction:
( ) ^{Total spread % x frequency(fo)}
10Log
0.12
dB
Total spread % x frequency(fo)x3
( ^10Log
0.12
) ^dB
( ) ^10Log
Total spread % x frequency(fo)x5
0.12
dB
ISO9001: 2000 Registered
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3 The Business Centre, Molly Millars Lane, Wokingham, Berks, RG41 2EY, UK
http://www.actcrystals.com
Page 3 of 5
Issue:4 M6
Date:26/10/05