PI6C671F Datasheet, PDF (1/7 Pages) Pericom Semiconductor Corporation – Clock Generator for Pentium Modules

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 V_DDQ2 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 V_DDQ1 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