Integrated

Circuit

Systems, Inc.

ICS94235

Third party brands and names are the property of their respective owners.

Block Diagram

94235 Rev A 01/17/02

Functionality

Pin Configuration

Recommended Application:

Output Features:

•

1 - Differential pair open drain CPU clocks

•

1 - Single-ended open drain CPU clock

•

13 - SDRAM @ 3.3V

•

7 - PCI @ 3.3V

•

2 - AGP @ 3.3V

•

1 - 48MHz, @3.3V

•

1 - REF @ 3.3V, (selectable strength) through I

Features:

•

Programmable ouput frequency

•

Programmable ouput rise/fall time

•

Programmable CPU, SDRAM, PCI and AGP skew

•

Real time system reset output

•

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

Skew Specifications:

•

CPUT - CPUC: <250ps

•

PCI - PCI: <500ps

•

CPU - SDRAM: <350ps

•

SDRAM - SDRAM: <250ps

•

AGP - AGP: <250ps

•

AGP - PCI: <750ps

•

CPU - PCI: <3ns

48-Pin 300mil SSOP &

240mil TSSOP package

RESET#

*PD#

GND

X1

X2

AVDD

**FS0/REF0

VDD

**FS1/AGP0

AGP1

GND

*FS2/PCICLK_F

PCICLK0

PCICLK1

PCICLK2

GND

VDD

*MODE/PCICLK3

PCICLK4

PCICLK5

AVDD48

**FS3/48MHz

GND

SCLK

GND

CPUCLKT0

CPUCLKC0

CPUCLKT1

SDATA

SDRAM0

SDRAM1

GND

VDD

SDRAM2

SDRAM3

SDRAM4

SDRAM5

VDD

GND

SDRAM6

SDRAM7

SDRAM8

SDRAM9

GND

VDD

SDRAM10(PCI_STOP#)*

SDRAM11

SDRAM12

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

PLL2

PLL1

Spread

Spectrum

48MHz

CPUCLKT (1:0)

SDRAM (12:0)

PCICLK (5:0)

AGP (1:0)

RESET#

2

6

13

2

PCICLK_F

CPUCLKC0

X1

X2

XTAL

OSC

CPU

DIVDER

SDRAM

DIVDER

PCI

DIVDER

AGP

DIVDER

Stop

Stop

Stop

SDATA

SCLK

FS (3:0)

PD#

PCI_STOP#

MODE

Control

Logic

Config.

Reg.

REF0

Power Groups

FS 3

FS 2

FS 1

FS 0

CP U

S DRAM

PCI

AGP

0

0

0

0

66.66

66.66

33.33

66.66

0

0

0

1

66.66

100.00

33.33

66.66

0

0

1

0

100.00

66.66

33.33

66.66

0

0

1

1

100.00

100.00

33.33

66.66

0

1

0

0

100.00

133.33

33.33

66.66

0

1

0

1

120.00

120.00

30.00

60.00

0

1

1

0

133.33

100.00

33.33

66.66

0

1

1

1

133.33

133.33

33.33

66.66

1

0

0

0

90.00

90.00

30.00

60.00

1

0

0

1

100.90

100.90

33.63

67.27

1

0

1

0

100.00

66.66

33.33

66.66

1

0

1

1

100.00

100.00

33.33

66.66

1

1

0

0

100.00

133.33

33.33

66.66

0

1

0

1

126.00

126.00

31.50

63.00

1

1

1

0

133.33

100.00

33.33

66.66

1

1

1

1

133.33

133.33

33.33

66.66