CY28159
Document #: 38-07118 Rev. **
Page 5 of 13
Spread Spectrum Clock Generation (SSCG)
Spread Spectrum is a modulation technique applied here for
maximum efficiency in minimizing Electro-Magnetic Interfer-
ence radiation generated from repetitive digital signals mainly
clocks. For a detailed explanation of Spread Spectrum Clock
Generation.
Power Management Functions
Notes:
2.
The entries in boldface are the primary system configurations of interest. The outputs should be optimized for these configurations.
3.
Rr refers to the resistance placed in series with the Iref input and VSS.
Table 4. Spectrum Spreading Selection Table
Unspread Frequency in MHz
Spread Spectrum Parameter
Downspreading
F Min(MHz)
F Center(MHz)
F Max(MHz)
Spread (%)
100
99.5
99.75
100
–0.5%
133.3
132.66
132.67
133
–0.5%
200
199.5
199.75
200
–0.5%
Table 5. Host Swing Select Functions[2]
Multsel0
MultSel1
Board Target
Trace/TermZ
Reference Rr, Iref = Vdd(3*Rr)
Note 3
Output Current
Voh@Z, Iref =
2.32 mA
00
60 Ohms
Rf = 475 1%,
Iref = 2.32 mA
Ioh = 5*Iref
07V@60
0
0
50 Ohms
Rr = 475 1%,Iref = 2.32 mA
Ioh = 5*Iref
0.59V @ 50
0
1
60 Ohms
Rr = 475 1%,Iref = 2.32 mA
Ioh = 6*Iref
0.85V @ 60
0
1
50 Ohms
Rr = 475 1%,Iref = 2.32 mA
Ioh = 6*Iref
0.71V @ 50
1
0
60 Ohms
Rr = 475 1%,Iref = 2.32 mA
Ioh = 4*Iref
0.56V @ 60
1
0
50 Ohms
Rr = 475 1%,Iref = 2.32 mA
Ioh = 4*Iref
0.47V @ 50
1
1
60 Ohms
Rr = 475 1%,Iref = 2.32 mA
Ioh = 7*Iref
0.99V @ 60
1
1
50 Ohms
Rr = 475 1%,Iref = 2.32 mA
Ioh = 7*Iref
0.82V @ 50
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