ICST MK1432STR, MK1434S, MK1434STR, MK1432S Datasheet

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ICST MK1432STR, MK1434S, MK1434STR, MK1432S Datasheet

MK1432/MK1434

Green PC and Local Bus Clock Source

Description

The MK1432 and MK1434 are low cost, high performance triple clock synthesizers for green PC and local bus desktop and notebook applications. Using analog Phase-Locked Loop (PLL) techniques, the devices accept a 14.318 MHz crystal input to produce multiple output clocks up to 100 MHz. They provide selectable 2XCPU and CPU, selectable local bus clock, ISA clock, and one fixed peripheral clock. The chips support PCI and VL buses. The fixed clock is either 24MHz or 40MHz. The devices can operate at 5V or 3.3V up to and including 80MHz on the 2XCPU clock.

The Power Saving pin causes the CPU clocks to smoothly transition to 33.33 MHz for Pentiums, and 16.67 MHz for 486DX4. In addition, a single pin can be made to slow DX2s to 8 MHz.

Features

• Packaged in 16 pin narrow (150 mil) SOIC

• Supports all Pentium Processor timing specs

Supports synchronous and asynchronous local bus

Selectable local bus frequencies of 25, 33, or 50MHz

SCSI or VL bus 40MHz clock on MK1434

Floppy or super I/O clock on MK1432

Single Power Saving pin switches to low power mode (for 486 and Pentium)

5V or 3.3V (up to 80MHz) operation

Smooth transitions for Pentium and 486 based Green PC

Low skew (<250ps) Pentium compatible

2X and 1X outputs

Duty cycle of 45/55 up to 100 MHz

25mA output drive capability at TTL levels

Compatible with all popular microprocessors

Packaged in 16 pin narrow SOIC

For Early Clock support, consult MicroClock

Block Diagram

 

VDD

GND

 

 

 

FS0

 

 

 

Output

2XCPU

FS1

 

 

 

Buffer

 

 

 

 

 

 

 

 

 

FS2

 

CPU

÷2

Output

CPU

 

 

Clocks

Buffer

PS

 

 

 

 

 

 

 

 

BCLKS

 

Local

 

Output

 

 

 

Bus

 

BCLK

 

 

 

Buffer

 

 

Clock

 

 

 

 

 

 

 

 

 

Fixed

 

Output

40.00 (MK1434)

 

 

 

or 24.00 MHz

X1

 

Clock

 

Buffer

 

 

(MK1432)

 

 

 

 

14.318 MHz

Crystal

 

 

 

 

 

 

 

crystal

Oscillator

 

Output

 

X2

 

 

 

14.318 MHz

 

 

 

Buffer

 

 

 

 

MDS 1432 G

1

Revision 060101

Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800 • www.icst.com

MK1432/MK1434

Green PC and Local Bus Clock Source

Pin Assignment

FS2

1

16

FS1

FS2

1

16

FS1

 

X2

2

15

2XCPU

 

X2

2

15

2XCPU

 

X1

3

14

CPU

 

X1

3

14

CPU

VDD

4

13

VDD

VDD

4

13

VDD

GND

5

12

GND

GND

5

12

GND

BCLK

6

11

14.3M

BCLK

6

11

14.3M

24M

7

10

FS0

40M

7

10

FS0

 

 

 

8

9

BCLKS

 

 

 

 

9

BCLKS

 

PS

 

PS

8

 

 

 

 

 

 

 

 

 

 

 

 

CPU Clock Decoding Table (in MHz)

 

 

 

F S 2

F S 1

F S 0

2XCPU

CPU

P S

1

 

0

0

0

16.00

8.00

 

1

 

0

0

1

00.00 note

50.00 note3

1

 

0

1

0

80.00

40.00

 

1

 

0

1

1

75.00

37.50

 

1

 

1

0

0

40.00

20.00

 

1

 

1

0

1

50.00

25.00

 

1

 

1

1

0

66.66

33.33

 

1

 

1

1

1

60.00

30.00

 

0

 

X

X

X

33.33

16.67

 

Local Bus Clock Decoding Table (in MHz)

BCLKS

BCLK (MHz)

 

0

25.00

 

M

33.33

 

1

50.00

 

Notes:

1.Actual frequencies are within 0.05% of those shown.

2.Transitions between mean frequencies on any CPU pin are smooth, and do not violate Intel’s 0.1% per cycle specification.

3.These selections are not guaranteed to operate at 3V.

4.M = mid level. Leave pin tri-stated, unconnected, or floating to select this level.

5.X = don’t care (either 0 or 1).

Pin Descriptions

 

1 4 3 2

 

1 4 3 4

Name

Type

Description

 

 

 

 

 

1

 

1

FS2

I

Select 2 for 2XCPU and CPU frequencies. See table above. Internal Pull-Up.

 

2

 

2

X2

O

Crystal connection. Connect to 14.31818 MHz crystal.

 

 

 

 

3

 

3

X1

I

Crystal connection. Connect to 14.31818 MHz crystal or clock.

 

4

 

4

VDD

P

Connect to +5V or 3.3V. Must be same voltage as pin 13.

 

 

 

 

5

 

5

GND

P

Connect to ground.

 

 

 

 

6

 

6

BCLK

O

Local Bus Clock output. See table above.

 

 

 

 

7

 

-

24M

O

24.00 MHz clock output (MK1432 only).

 

 

 

 

-

 

7

40M

O

40.00 MHz clock output (MK1434 only).

 

 

 

 

8

 

8

 

 

 

I

Power Saving pin. Smoothly changes CPU to/from 33.33 and 16.67 MHz. IPU

 

 

 

PS

 

9

 

9

BCLKS

TI

Local Bus Clock Select pin. See table above.

 

 

 

 

10

 

10

FS0

I

Select 0 for 2XCPU and CPU frequencies. See table above. Internal Pull-Up.

 

11

 

11

14.3M

O

14.318 MHz Reference Clock Output.

 

 

 

 

12

 

12

GND

P

Connect to ground.

 

 

 

 

13

 

13

VDD

P

Connect to +5V or 3.3V. Must be same voltage as pin 4.

 

 

 

 

14

 

14

CPU

O

CPU Clock output. See table above for frequencies.

 

 

 

 

15

 

15

2XCPU

O

2X CPU Clock output. See table above for frequencies.

 

 

 

 

16

 

16

FS1

I

Select 1 for 2XCPU and CPU frequencies. See table above. Internal Pull-Up.

 

 

Key: TI = Tri-level Input, I = Input, O = output, P = power supply connection

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

MDS 1432 G

 

 

 

 

 

2

Revision 060101

Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800 • www.icst.com

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