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PS8164B

03/15/99

PI6C104

Spread Spectrum Clock Synthesizer

for Desktop Pentium II

PCICLK_F/S1

PCICLK1

VSS

PCICLK3

PCICLK4

PCICLK2

PCICLK5

PCICLK6/PD#

VDD

48M/MODE

24M/REF/S2

VSS

VDD

VDD2

VDD2

CPUCLK0

CPUCLK1

VDD

VSS

SDATA

SCLK

S0

VSS

1

2

3

4

5

6

7

8

9

10

11

12

13

14

28

27

26

25

24

23

22

21

20

19

18

17

16

15

XTAL_IN

XTAL_OUT

VDD

APIC

REF1/P14

PinConfiguration

BlockDiagram

Features

• Up to 112 MHz operation

• SpreadSpectrumModulationforCPUCLK,andPCICLK

• Seven copies of PCI clock,

(synchronous with CPU clock) 3.3V

• 48MHzUSBClock,24MHzSuperI/Oclock

• Low cost 14.31818MHz crystal oscillator input

• Power management control

• 28-pin SSOP (H) and SOIC package (S)

Description

The PI6C104 is a high-speed low-noise clock generator designed

to work with the PI6C18X family of clock buffer to meet all clock

needs for Desktop Intel Architecture platforms. CPU and chipset

clock frequencies from 66.6 MHz to 112 MHz are supported.

Split supplies of 3.3V and 2.5V are used. The 3.3V power supply

powers a portion of the I/O and the core. The 2.5V is used to power

the remaining outputs (CPU and APIC). 2.5V signaling follows

JEDEC standard 8-X. Power sequencing of the 3.3V and 2.5V

supplies is not required.

An asynchronous PD# signal may be used to orderly power down

(or up) the system during power on.

28-Pin

H, S

REF1

APIC

PCICLK[1:6]

CPUCLK[0:1]

REF

OSC

2

6

PCICLK_F

Div

PLL1

SEL

XTAL_OUT

XTAL_IN

S[0..2]

SCLOCK

PLL2

PI4

48MHz

24MHz/REF

MUX