cy27020 Cypress Semiconductor Corporation., cy27020 Datasheet - Page 2

• Manufacturer Part Number: cy27020
• Description: Ic Ss Clock Generator 8-soic
• Manufacturer: Cypress Semiconductor Corporation.

Pin Configuration
Pin Description
Spread Spectrum Clock Generation (SSCG)
Spread Spectrum Clock Generator (SSCG) is a frequency
modulation technique used to reduce electromagnetic inter-
ference radiation generated by repetitive digital signals, mainly
clocks. A clock accumulates EM energy at its center frequency
and its harmonics. Spread Spectrum distributes this energy over
a small frequency bandwidth and decreases the peak value of
radiated energy over the spectrum. This technique is achieved
by modulating the clock around or below the center of its resting
frequency by a certain percentage (which also determines the
energy distribution bandwidth).
The SSCG function is enabled when SSON pin is asserted low
resulting in a spread bandwidth that is down spread by either
–1% or –3% selected by SSSEL (see
Note
Document #: 38-07273 Rev. *C
1. PU = Internal Pull-up, PD = Internal Pull-down.
Pin
1
2
3
4
5
6
7
8
REFOUT
CLKOUT
SSSEL
SSON
Name
XOUT
VDD
VSS
XIN
PWR
PWR
I/o
O
O
O
I
I
I
Type
PU
PD
–
[1]
Fixed Frequency 48.00 MHz Spread Spectrum Clock Output. See
frequency selections
3.3V Power Supply
Common Ground
Oscillator Buffer Input. Connect to an external parallel resonant crystal (nominally 48.00
MHz) or externally generated 48 MHz reference clock.
Oscillator Buffer Output. Connect to an external parallel resonant crystal. Do not connect
when an externally generated reference clock is applied at XIN.
Spread Spectrum Bandwidth (BW%) Selection Input. See
Buffered Output of XIN.
Spread Spectrum Enable Input. When asserted LOW, Spread Spectrum is enabled.
Table 1
CLKOUT
on page 1).
VDD
VSS
XIN
Figure 1. 8-Pin SOIC
1
2
3
4
.
Figure 2. Down Spread
Description
8
7
6
5
SSSEL
REFOUT
XOUT
SSON
Table 1
on page 1 for selections.
Table 1
on page 1 for
CY27020(s)
Page 2 of 6
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