Low EMI Spectrum Spread Clock
FS791/92/94
Cypress Semiconductor Corporation
•
3901 North First Street
•
San Jose
•
CA 95134
•
408-943-2600
Document #: 38-07343 Rev *A
Revised December 28, 2002
92/94
Features
• Spread Spectrum Clock Generator (SSCG) with 1x, 2x
and 4x outputs
• 80- to 140-MHz operating frequency range
• Modulates external clocks including crystals, crystal
oscillators, and ceramic resonators
• Programmable modulation with simple R-C external
loop filter (LF)
• Center spread modulation
• 3–5 Volt power supply
• TTL/CMOS compatible outputs
• Low short-term jitter
• Low Power Dissipation;
— 3.3 VDC = 73 mW—typical
— 5.0 VDC = 225 mW—typical
• Available in 8-pin SOIC package
.
Applications
• Desktop/Notebook computers
• VGA, XGA, and SXGA LCD displays
• High-speed printers and copiers
• CD-ROM, VCD, and DVD
• Embedded systems
• Networking, LAN/WAN
• Modems
Benefits
• Programmable EMI reduction
• Fast time-to-market
• Lower cost of compliance
• No degradation in Rise/Fall time
• Lower component and PCB layer count
Block Diagram
Pin Configuration
Phase
Detector
VCO
1
2
Xin
Xout
10 pF.
Reference
Divider
10 pF.
10 pF.
VCO / N
Modulation
Control
Input Control
Counter
and
Mux
Power Contol
Logic
3
7
8
5
4
VDD
S0
S1
FSOUT
Loop Filter
VSS
6
1
2
3
4
8
7
6
5
Xin
Xout
S1
LF
VDD
S0
FSOUT
VSS
FS79x
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