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P
www.fairchildsemi.com
Preliminary Specification 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.
I
2
C is a trademark of Philips Corporation
Rev. 0.8.2
Features
Employs Fairchild’s proprietary Spread Spectrum
Technology
Reduces measured EMI by as much as 10dB
Supports up to 150MHz
¥
I
2
C programmable
Two copies of CPU clock with one free running
One copy 24MHz clock
One copy 48MHz clock
One copy IOAPIC
Two copy REF 14.318MHz clock (3.3V)
Six copies PCI clock
Thirteen copies of SDRAM clock with one free running
PCI/CPU stop capability
Description
The RC7144 is a clock synthesizer for motherboard applica-
tions. It meets the requirements for the 133MHz 13x/zx
chipset. The clock frequencies can be set with the 4 select
pins or can be set via the I
2
C interface.
Block Diagram
IOAPIC
C
O
N
T
R
O
L
L
O
G
I
C
CPU1
CPU_F
PCI_F/MODE
PCI1/FS3
PCI2:5
SDRAM_F
REF0/PCI_STOP#
PLL1
Spread
Spectrum
PLL2 USB
I2C
Registers
XTAL
OSC
REF1/FS2
X1
X2
SDA
CLK_STOP#
SCL
SDRAM0:11
48MHz/FS0
SDRAMIN
24MHz/FS1
RC7144
133MHz S pread S pec trum Motherboard Integrated
Cloc k/Buffer