ICS557-05A
Quad Differential PCI-Express Clock Source
Description
Features
The ICS557-05A is a spread-spectrum clock generator
that supports PCI-Express requirements. It is used in
PC or embedded systems to substantially reduce
electro-magnetic interference (EMI). The device
provides four differential HCSL or LVDS high-frequency
outputs with spread spectrum capability. The output
frequency and spread type are selectable using
external pins.
• Packaged in 20-pin TSSOP
• Available in Pb (lead) free package
• Supports PCI-Express applications
• Four differential spread spectrum clock outputs
• Spread spectrum for EMI reduction
• Uses external 25 MHz clock or crystal input
• Power down pin turns off chip
• OE control tri-states outputs
• Spread and frequency selection via external pins
• Spread Bypass option available
• Industrial temperature range available
Block Diagram
VDD
PD
OE
2
Spread
Spectrum/
Output
Spread
Spectrum
Circuitry
3
SEL[2:0]
X1
clock
selection
CLKOUTA
CLKOUTA
CLKOUTB
25 MHz
crystal or
clock
Clock
Oscillator
PLL Clock
Synthesis
CLKOUTB
CLKOUTC
X2
CLKOUTC
CLKOUTD
Optional tuning crystal
capacitors
CLKOUTD
2
Rr(IREF)
GND
MDS 557-05A E
1
Revision 011606
Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
ICSI [ INTEGRATED CIRCUIT SOLUTION INC ]
