PI6C671F
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Clock Generator for Pentium Modules
Features
Supports Pentium or Pentium II CPU modules
Spread Spectrum capability reduces EMI
Low power consumption
Four CPU Clocks with VDDQ2 of 3.3V or 2.5V
Enhanced drive on CPUCLK0
Seven PCI synchronous clocks (3.3V)
One IOAPIC Clock @14.31818 MHz
(Power from pin 46), with VDDQ1 of 3.3V or 2.5V
Two 48/24 MHz clocks (3.3V)
Six/eight SDRAM clocks (3.3V)
Three Ref. Clocks @14.31818 MHz (3.3V)
Internal crystal loading capacitor
Ref. 14.31818 MHz crystal oscillator input
Separate 66/60# MHz select pin
Separate power management MODE control pin
I2C 2-Wire Serial Interface
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 I2C serial interface can be used to reduce circuit
noise and power consumption. I2C 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 CPU_STOP# (pin 27), and
PCI _STOP# (pin 26) functions.
Note: Purchase of I2C components from Pericom conveys a license
to use them in an I2C system as defined by Philips.
Block Diagram
Pin Configuration
XIN
XOUT
SEL
REF
OSC
PLL1
PLL2
÷2
Buffers
VDDQ1
VDDQ2
VDDQ3
3
REF0,1,2
IOAPIC0
4
CPUCLK0-3
Up to 8
SDRAM0-7
6
PCICLK0-5
PCICLK_F
48/24 MHz
48/24 MHz
All trademarks are of their respective companies.
REF1
REF0
VSS
XIN
XOUT
MODE
VDDQ3
PCICLK_F
PCICLK0
VSS
PCICLK1
PCICLK2
PCICLK3
PCICLK4
VDDQ3
PCICLK5
VSS
SEL66/60#
SDATA
SDCLK
VDDQ3
48/24MHz
48/24MHz
VSS
1
48
2
47
3
46
4
45
5
44
6
43
7
42
8
41
9
40
10 48-Pin 39
11
38
12 A, V 37
13
36
14
35
15
34
16
33
17
32
18
31
19
30
20
29
21
28
22
27
23
26
24
25
VDD
REF2
VDDQ1
IOAPIC0
PWR_DWN#
VSS
CPUCLK0
CPUCLK1
VDDQ2
CPUCLK2
CPUCLK3
VSS
SDRAM0
SDRAM1
VDDQ3
SDRAM2
SDRAM3
VSS
SDRAM4
SDRAM5
VDDQ3
SDRAM6/CPU_STOP#
SDRAM7/PCI_STOP#
VDD
392
PS8137A 03/15/99