3.3V PENTIUM鈩?/div>
CLOCK SYNTHESIZER
IDT74FCT3907
ADVANCE INFORMATION
COMMERCIAL TEMPERATURE RANGES
Integrated Device Technology, Inc.
FEATURES:
鈥?0.5 MICRON CMOS Technology
鈥?Generates keyboard, floppy disk, system reference, PCI
and CPU clocks
鈥?6 copies of PCI clock & 4 copies of CPU clock available
鈥?14.31818MHz crystal input
鈥?CPU clock output skew <250ps
Bus clock output skew <500ps
鈥?0.03% output frequency accuracy
鈥?Power-on reset
鈥?Selectable CPU clock frequency (50/60/66.66MHz)
鈥?Internal loop filter
鈥?V
CC
= 3.3 鹵0.3V
鈥?Available in 28 pin SOIC
鈥?Supports Pentium鈩?processor based designs
鈥?Meets Intel Pentium鈩?processor 3.3V Clock Driver
specification (External Draft 1.0)
DESCRIPTION:
The IDT74FCT3907 Clock synthesizer is built using ad-
vanced dual metal CMOS technology. This device uses a
14.31818 MHz crystal input to synthesize the various
motherboard clock frequencies.
The output frequencies supported by the IDT74FCT3907
are as follows:
Reference clocks (2) = 14.31818MHz
Keyboard clock (1) = 12MHz
Floppy disk clock (1) = 24MHz
CPU clock (4) = 50/60/66.66 MHz (Selectable by SEL pins)
Bus clock (6) = CPU clock 梅 2
The SEL0, 1 pins are used to choose appropriate CPUCLK
and PCICLK frequencies or to put the device in a test mode.
In the test mode, the device outputs various divisors of the test
clock frequency. Refer to the function table in this datasheet
for details on the different operating modes.
FUNCTIONAL BLOCK DIAGRAM
1
X1
(14.31818 MHz)
X2
Oscillator
Peripheral
Clock
Synthesizer
Block
KBCLK (12MHz)
1
FDCLK (24MHz)
4
SEL0, 1
CPU
Clock
Synthesizer
Block
CPUCLK 0-3
6
PCICLK 0-5
2
REF CLK 0,1 (14.31818 MHz)
OE
3245 drw 01
The IDT logo is a registered trademark of Integrated Device Technology, Inc.
Pentium鈩?is a trademark of Intel Corp.
COMMERCIAL TEMPERATURE RANGES
漏1995 Integrated Device Technology, Inc.
AUGUST 1995
9.10
DSC-4662/-
1
1
1
2
3
4
5
6
7
