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PI6C671F
Clock Generator for Pentium Modules
Features
聲
Supports Pentium or Pentium II CPU modules
聲
Spread Spectrum capability reduces EMI
聲
Low power consumption
聲
Four CPU Clocks with V
DDQ2
of 3.3V or 2.5V
聲 Enhanced drive on CPUCLK0
聲
Seven PCI synchronous clocks (3.3V)
聲
One IOAPIC Clock @14.31818 MHz
(Power from pin 46), with V
DDQ1
of 3.3V or 2.5V
聲
Two 48/24 MHz clocks (3.3V)
聲
Six/eight SDRAM clocks (3.3V)
聲
Three Ref. Clocks @14.31818 MHz (3.3V)
聲
Internal crystal loading capacitor
聲
Ref. 14.31818 MHz crystal oscillator input
聲
Separate 66/60# MHz select pin
聲
Separate power management MODE control pin
聲
I
2
C
2-Wire Serial Interface
聲
48-pin SSOP Package (V) and TSSOP (A)
Description
The PI6C671F is a mixed-voltage clock generator designed to
provide all timing signals for Intel Pentium/Pentium II module-based
motherboards. It provides four CPU, seven PCI, and up to eight
SDRAM clocks. Additionally, three reference clocks (same fre-
quency as the crystal) and two selectable 24/48 MHz clocks are
available.
Pericom design improvements resulted in a low-power device
optimized for 2.5V CPU operation. A special spread-spectrum
feature may be enabled to minimize EMI.
The two-wire I
2
C serial interface can be used to reduce circuit
noise and power consumption. I
2
C control lets you enable/disable
each clock output driver, change CPU frequencies, and select 24 or
48 MHz outputs.
A power-down function (pin 44) puts the whole system in a low-
power mode by stopping the crystal oscillator and both PLLs. CPU
and PCI clocks may also be stopped by the 聯(lián)CPU_STOP#聰 (pin 27), and
聯(lián)PCI _STOP#聰 (pin 26) functions.
Note:
Purchase of I
2
C components from Pericom conveys a license
to use them in an I
2
C system as defined by Philips.
Block Diagram
Buffers
Pin Configuration
REF1
REF0
V
SS
XIN
XOUT
MODE
V
DDQ
3
PCICLK_F
PCICLK0
V
SS
PCICLK1
PCICLK2
PCICLK3
PCICLK4
V
DDQ
3
PCICLK5
V
SS
SEL66/60#
SDATA
SDCLK
V
DDQ
3
48/24MHz
48/24MHz
V
SS
48
1
47
2
46
3
45
4
44
5
43
6
42
7
41
8
40
9
10
48-Pin
39
38
11
A, V
37
12
13
36
14
35
15
34
16
33
17
32
18
31
19
30
20
29
21
28
22
27
23
26
25
24
V
DD
REF2
V
DDQ
1
IOAPIC0
PWR_DWN#
V
SS
CPUCLK0
CPUCLK1
V
DDQ
2
CPUCLK2
CPUCLK3
V
SS
SDRAM0
SDRAM1
V
DDQ
3
SDRAM2
SDRAM3
V
SS
SDRAM4
SDRAM5
V
DDQ
3
SDRAM6/CPU_STOP#
SDRAM7/PCI_STOP#
V
DD
3
XIN
REF0,1,2
REF
OSC
XOUT
IOAPIC0
V
DDQ
1
V
DDQ
2
4
CPUCLK0-3
V
DDQ
3
PLL1
SEL
Up to 8
SDRAM0-7
梅
2
6
PCICLK0-5
PCICLK_F
48/24 MHz
PLL2
48/24 MHz
All trademarks are of their respective companies.
392
PS8137A
03/15/99
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