Electronic Components Datasheet Search
  English  ▼

Delete All


Preview PDF Download HTML

W210H Datasheet(PDF) 4 Page - Cypress Semiconductor

Part No. W210H
Description  Spread Spectrum FTG for VIA K7 Chipset
Download  14 Pages
Scroll/Zoom Zoom In 100% Zoom Out
Maker  CYPRESS [Cypress Semiconductor]
Homepage  http://www.cypress.com

W210H Datasheet(HTML) 4 Page - Cypress Semiconductor

Zoom Inzoom in Zoom Outzoom out
 4 / 14 page
background image
Spread Spectrum Frequency Timing Generator
The device generates a clock that is frequency modulated in
order to increase the bandwidth that it occupies. By increasing
the bandwidth of the fundamental and its harmonics, the am-
plitudes of the radiated electromagnetic emissions are re-
duced. This effect is depicted in Figure 3.
As shown in Figure 3, a harmonic of a modulated clock has a
much lower amplitude than that of an unmodulated signal. The
reduction in amplitude is dependent on the harmonic number
and the frequency deviation or spread. The equation for the
reduction is:
dB = 6.5 + 9*log10(P) + 9*log10(F)
Where P is the percentage of deviation and F is the frequency
in MHz where the reduction is measured.
The output clock is modulated with a waveform depicted in
Figure 4. This waveform, as discussed in “Spread Spectrum
Clock Generation for the Reduction of Radiated Emissions” by
Bush, Fessler, and Hardin produces the maximum reduction
in the amplitude of radiated electromagnetic emissions. The
deviation selected for this chip is specified in Table 6. Figure 4
details the Cypress spreading pattern. Cypress does offer op-
tions with more spread and greater EMI reduction. Contact
your local Sales representative for details on these devices.
Spread Spectrum clocking is activated or deactivated by se-
lecting the appropriate values for bits 1–0 in data byte 0 of the
I2C data stream. Refer to Table 6 for more details.
Figure 3. Clock Harmonic with and without SSCG Modulation Frequency Domain Representation
Typical C lo ck
Freq uency S pan (M H z)
-S S%
+SS %
5 d B /d iv
Figure 4. Typical Modulation Profile
MAX (0%)
MIN (–0.5%)

Html Pages

1  2  3  4  5  6  7  8  9  10  11  12  13  14 

Datasheet Download

Link URL

Privacy Policy
Does ALLDATASHEET help your business so far?  [ DONATE ]  

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Alldatasheet API   |   Link Exchange   |   Manufacturer List
All Rights Reserved© Alldatasheet.com

Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn