© Semiconductor Components Industries, LLC, 2006

June, 2006 − Rev. 7

1

Publication Order Number:

SN74LS155/D

SN74LS155

DUAL 1-OF-4 DECODER/

DEMULTIPLEXER

The SN54 / 74LS156 is a high speed Dual 1-of-4

Decoder/Demultiplexer. This device has two decoders with common

2-bit Address inputs and separate gated Enable inputs. Decoder “a”

has an Enable gate with one active HIGH and one active LOW input.

Decoder “b” has two active LOW Enable inputs. If the Enable

functions are satisfied, one output of each decoder will be LOW as

selected by the address inputs. The LS156 has open collector outputs

for wired-OR (DOT-AND) decoding and function generator

applications.

The LS156 is fabricated with the Schottky barrier diode process for

high speed and are completely compatible with all Motorola TTL

families.

CONNECTION DIAGRAM DIP (TOP VIEW)

NOTE:

The Flatpak version

has the same pinouts (Connection

Diagram) as the Dual In-Line Pack-

age.

14

13

12

11

10

9

12345

6

7

16

15

8

PIN NAMES

LOADING (Note a)

HIGH

LOW

Address Inputs

Enable (Active LOW) Inputs

Enable (Active HIGH) Input

Active LOW Outputs (Note b)

0.5 U.L.

0.5 U.L.

0.5 U.L.

10 U.L.

0.25 U.L.

0.25 U.L.

0.25 U.L.

5 (2.5) U.L.

NOTES:

a) 1 TTL Unit Load (U.L.) = 40 μA HIGH/1.6 mA LOW.

b) The Output LOW drive factor is 2.5 U.L. for Military (54) and 5 U.L. for Commercial (74)

Temperature Ranges. The HIGH level drive for the LS156 must be established by an

external resistor.

http://onsemi.com

DUAL 1-OF-4 DECODER/

DEMULTIPLEXER

LS156-OPEN-COLLECTOR

LOW POWER SCHOTTKY

J SUFFIX

CERAMIC

CASE 620-09

N SUFFIX

PLASTIC

CASE 648-08

16

1

16

1

ORDERING INFORMATION

SN54LSXXXJ

Ceramic

SN74LSXXXN Plastic

SN74LSXXXD SOIC

16

1

D SUFFIX

SOIC

CASE 751B-03

LOGIC SYMBOL

GND = PIN 8

1 2

13 3

14 15

EE

012

3

0

123

DECODER a

DECODER b

7 6 5

4

9 10 11 12