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ADVANCED INFORMATION
describes products that are not in full production at the time of printing. Specifications are based on design goals
and limited characterization. They may change without notice. Contact Fairchild Semiconductor for current information.
www.fairchildsemi.com
Features
Employs Fairchild’s proprietary Spread Spectrum
Technology
Reduces measured EMI by as much as 10dB
¥
I
2
C programmable
Two skew-controlled copies of CPU clock
SEL100/66# selects CPU frequency (100 or 66.8MHz)
Overclocking up to 133MHz
Seven copies of PCI clock (synchronous w/CPU clock)
One copy of 14.31818 MHz IOAPIC clock
One copy of 48MHz USB clock
24 or 48MHz clock is determined by resistor straps
on power up
One copy of 14.31818MHz REF clock
Description
The RC7104 is a clock synthesizer for Pentium II based
motherboard systems. The CPU output frequency can be
“over driven” through a command to the serial I
2
C interface.
RC7104
100MHz S pread S pec trum Motherboard Cloc k
Block Diagram
REF/SEL48#
GNDREF
VDDAPIC
IOAPIC
X1
XTAL
OSC
PLL 1
I
2
C
LOGIC
PLL 2
X2
VDDCORE1
PLL Ref Freq
VDDREF
100/66#_SEL
SDATA
SCLOCK
CPU0
VDDCPU
CPU1
GNDCPU
VDDPCI
PCI_F
PCI1
PCI2
PCI3
PCI4
PCI5
PCI6
GNDPCI
48MHz
VDD48
24/48MHz
GND48MHz
÷
2/
÷
3
Rev. 0.0.9