Cypress Semiconductor CY25566 Spezifikationsblatt - Seite 4

Blättern Sie online oder laden Sie pdf Spezifikationsblatt für Computer Hardware Cypress Semiconductor CY25566 herunter. Cypress Semiconductor CY25566 9 Seiten. Cypress spread spectrum clock generator specification sheet

Seite drucken
Modulation Rate
Spread
Spectrum
clock
modulation (FM) to distribute energy over a specific band of
frequencies. The maximum frequency of the clock (Fmax) and
minimum frequency of the clock (Fmin) determine this band of
frequencies. The time required to transition from Fmin to Fmax
and back to Fmin is the period of the Modulation Rate, Tmod.
Modulation Rates of SSCG clocks are generally referred to in
terms of frequency or Fmod = 1/Tmod.
The input clock frequency, Fin, and the internal divider count,
Cdiv, determine the Modulation Rate. The CY25566 utilizes
two different modulation rate dividers, depending on the range
selected on S2 and S3 digital control inputs. Refer to the
example below.
S3, S2
CDiv
0,0
1166
0,1
1166
1,0
2332
1,1
N/A
Example:
Device = CY25566
Fin = 65 MHz
Range = S3 = 0, S2 = 1, S0 = 0
Then: modulation rate = Fmod = 65 MHz/1166 = 55.7 kHz
Modulation Profile
Document #: 38-07429 Rev. *B
generators
utilize
frequency
Output Frequency
1X
2X
1X
N/A
Figure 3. SSCG Clock, CY25566, 65 MHz
The CY25566 has three frequency groups to select from. Each
combination of frequency and bandwidth can be selected by
programming the input control lines, S0–S3, to the proper logic
state.
Group 1 is the 1X low-frequency range and operates from 25
to 100 MHz.
Group 2 is the 1X high-frequency range and operates from 50
to 200 MHz.
Group 3 is the 2X low frequency range and operates from 25
to 50 MHz and 50 to 100 MHz output.
Spectrum Analyzer
CY25566
Page 4 of 9
[+] Feedback