2

ICS9158-05

Advanced Information

Pin Configuration

Pin Descriptions for ICS9158-05

24-Pin SOIC

* Input pin has internal pull-up to VDD.

Functionality

VDD = +5V±10%, TA=0°C to 70°C unless otherwise stated

PD# forces all outputs low and powers-down the oscillator and PLL

circuitry, minimizing power consumption. In order to ensure glitch-free start

and stop of the CPU and BUS clocks, PD# should be asserted after the

CPU and BUS clocks have stopped, and be deasserted 10ms (maximum

PLL lock time) prior to starting the clocks.

OE

PD#

FLOPPY (MHz)

KEYBD (MHz)

1

1

24

12

1

0

Low

Low

0

X

Tristate

Tristate

PIN NUMBER

PIN NAME

TYPE

DESCRIPTION

1

REFCLK

OUT

14.318 clock output.

2

X2

OUT

Crystal connection, which includes output crystal load capacitance.

3X1

IN

Crystal connection, which includes crystal load capacitance and feedback bias

for a nominal 14.31818 MHz parallel-resonance 12pF crystal.

4

VDD

PWR

Digital POWER SUPPLY.

5

GND

PWR

Digital GROUND.

6

KEYBD

OUT

12 MHz keyboard clock output.

7

FLOPPY

OUT

24 MHz floppy disk clock output.

8

BUS0

OUT

BUS clock output.

9

AGND

PWR

ANALOG GROUND.

10

OE

IN

OUTPUT ENABLE. Tristates all outputs when low.*

11

BUS1

OUT

BUS clock output.

12

GND

PWR

Digital GROUND.

13

CPU0

OUT

CPU clock output.

14

CPU1

OUT

CPU clock output.

15

PD#

IN

Power-down input shuts off both PLL stages when low.*

16

AVDD

PWR

ANALOG power supply.

17

BUS2

OUT

CPU clock output.

18

BUS3

OUT

BUS clock output.

19

GND

PWR

Digital GROUND.

20

VDD

PWR

Digital POWER SUPPLY.

21

CPU2

OUT

CPU clock output.

22

BUS4

OUT

BUS clock output.

23

FS1

IN

Clock frequency select #1.*

24

FS0

IN

Clock frequency select #0.*

OE

PD#

FS1

FS0

CPU

Ratio

X1,X2,

REF

(MHz)

CPU

(0:2)

(MHz)

BUS

(0:4)

(MHz)

1

1

0

0

14/4xX1

14.318

50

25

1

1

0

1

14/3xX1

14.318

66.7

33.3

1

1

1

0

42/10xX1

14.318

60

30

1

1

1

1

(STOP)

14.318

Low

Low

10

X

X

(PWR

DOWN)

Low

*Low

*Low

0

X

X

X

-

Tristate

Tristate

Tristate