ISL8485, ISL8490, ISL8491

FN6046 Rev 10.02

Page 4 of 15

Oct 2, 2023

Truth Tables

Pinouts

ISL8485 (PDIP, SOIC)

TOP VIEW

ISL8490 (SOIC)

TOP VIEW

ISL8491 (SOIC)

TOP VIEW

RO

RE

DE

DI

1

2

3

4

8

7

6

5

VCC

B/Z

A/Y

GND

D

R

VCC

RO

DI

GND

1

2

3

4

8

7

6

5

A

B

Z

Y

D

R

NC

RO

RE

DE

DI

GND

GND

VCC

NC

A

B

Z

Y

NC

1

2

3

4

5

6

7

14

13

12

11

10

9

8

D

R

Pin Descriptions

PIN

FUNCTION

RO

Receiver output: RO is high if A > B by at least 0.2V; RO is low if A < B by 0.2V or more; RO = high if A and B are unconnected (floating).

RE

Receiver output enable. RO is enabled when RE is low; RO is high impedance when RE is high.

DE

Driver output enable. The driver outputs Y and Z are enabled by bringing DE high. They are high impedance when DE is low.

DI

Driver input. A low on DI forces output Y low and output Z high. Similarly, a high on DI forces output Y high and output Z low.

GND

Ground connection.

A/Y

Noninverting receiver input and noninverting driver output. Pin is an input (A) if DE = 0; pin is an output (Y) if DE = 1.

B/Z

Inverting receiver input and inverting driver output. Pin is an input (B) if DE = 0; pin is an output (Z) if DE = 1.

A

Noninverting receiver input.

B

Inverting receiver input.

Y

Noninverting driver output.

Z

Inverting driver output.

VCC

System power supply input (4.5V to 5.5V).

NC

No connection.

TRANSMITTING

INPUTS

OUTPUTS

RE

DE

DI

Z

Y

X

1101

X

1010

0

0

X

High-Z

High-Z

RECEIVING

INPUTS

OUTPUT

RE

DE

Half Duplex

DE

Full Duplex

A-B

RO

00

X

≥ +0.2V

1

00

X

≤ -0.2V

0

0

0

X

Inputs Open

1

111

X

High-Z