ICS951901

Integrated

Circuit

Systems, Inc.

0670B—07/15/04

Programmable Frequency Generator & Integrated Buffers for Pentium III Processor

Block Diagram

Recommended Application:

Single chip clock solution for IA platform.

Output Features:

•

3 - CPU @ 2.5V

•

13 - SDRAM @ 3.3V

•

6 - PCI @3.3V,

•

2 - AGP @ 3.3V

•

1 - 48MHz, @3.3V fixed.

•

1 - 24/48MHz, @3.3V selectable by I

(Default is 24MHz)

•

2 - REF @3.3V, 14.318MHz.

Features:

•

Programmable ouput frequency.

•

Programmable ouput rise/fall time.

•

Programmable SDRAM and CPU skew.

•

Spread spectrum for EMI control typically

by 7dB to 8dB,

with programmable spread percentage.

•

Watchdog timer technology to reset system

if over-clocking causes malfunction.

•

Uses external 14.318MHz crystal.

•

FS pins for frequency select

Skew Specifications:

•

CPU - CPU: < 175ps

•

SDRAM - SDRAM < 250ps (except SDRAM12)

•

PCI - PCI: < 500ps

•

CPU (early) - PCI: 1-4ns (typ. 2ns)

Functionality

Pin Configuration

48-Pin 300mil SSOP

* These inputs have a 120K pull down to GND.

PLL2

PLL1

Spread

Spectrum

48MHz

24_48MHz

CPUCLK (2:0)

SDRAM (12:0)

PCICLK (4:0)

AGP (1:0)

PCICLK_F

2

5

13

3

2

X1

X2

XTAL

OSC

CPU

DIVDER

SDRAM

DIVDER

PCI

DIVDER

Stop

Stop

Stop

SDATA

SCLK

FS(3:0)

PD#

PCI_STOP#

CPU_STOP#

SDRAM_STOP#

MODE

AGP_SEL

Control

Logic

Config.

Reg.

/ 2

REF(1:0)

AGP

DIVDER

VDDA

(AGPSEL)REF0

*(FS3)REF1

GND

X1

X2

VDDPCI

*(FS1)PCICLK_F

*(FS2)PCICLK0

PCICLK1

PCICLK2

PCICLK3

PCICLK4

GND

VDDAGP

AGPCLK0

AGPCLK1

GND

GND

*(FS0)48MHz

*(MODE)24_48MHz

VDD48

SDATA

SCLK

1

1

*

VDDL

CPUCLK0

CPUCLK1

CPUCLK2

GND

VDDSDR

SDRAM0

SDRAM1

SDRAM2

GND

SDRAM3

SDRAM4

SDRAM5

VDDSDR

SDRAM6

SDRAM7

GND

SDRAM8/PD#

SDRAM9/SDRAM_STOP#

GND

SDRAM10/PCI_STOP#

SDRAM11/CPU_STOP#

SDRAM12

VDDSDR

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

48

47

46

45

44

43

42

41

40

39

38

37

36

35

34

33

32

31

30

29

28

27

26

25

FS3FS2

FS1FS0

CPU

SDRAM

PCI

AGP1

AGP0

Bit7

Bit6

Bit5

Bit4

MHz

MHz

MHz

SEL=1

SEL=0

0

0

0

0

0

66.67

66.67

33.33

66.67

64

0

0

0

0

1

66.67

100.00

33.33

66.67

64

0

0

0

1

0

66.67

133.34

33.33

66.67

64

0

0

0

1

1

75.00

75.00

37.50

75.00

64

0

0

1

0

0

83.31

83.31

33.32

66.64

64

0

0

1

0

1

90.00

90.00

30.00

60.00

64

0

0

1

1

0

95.00

95.00

31.67

63.33

64

0

0

1

1

1

100.00

66.67

33.33

66.67

64

0

1

0

0

0

100.00

100.00

33.33

66.67

64

0

1

0

0

1

100.00

133.34

33.33

66.67

64

0

1

0

1

0

105.00

105.00

35.00

70.00

64

0

1

0

1

1

112.00

112.00

33.60

67.20

64

0

1

1

0

0

117.99

117.99

35.40

70.80

64

0

1

1

0

1

124.09

124.09

31.02

62.05

64

0

1

1

1

0

133.34

100.00

33.33

66.67

64

0

1

111

133.34

133.34

33.33

66.67

64

Bit2