MOTOROLA MC74ACT157ML1, MC74ACT157DT, MC74ACT157DTEL, MC74ACT157DTR2, MC74ACT157M Datasheet

Quad 2 Input Multiplexer

The MC74AC157/74ACT157 is a high-speed quad 2-input multiplexer. Four

bits of data from two sources can be selected using the common Select and Enable inputs. The four outputs present the selected data in the true (noninverted) form. The MC74AC157/74ACT157 can also be used as a function generator.

•Outputs Source/Sink 24 mA

•′ACT157 Has TTL Compatible Inputs

VCC

E

I0c

I1c

Zc

I0d

I1d

Zd

16

15

14

13

12

11

10

9

PIN NAMES

I0a±I0d

Source 0 Data Inputs

I1a±I1d

Source 1 Data Inputs

E

Enable Input

1

2

3

4

5

6

7

8

S

Select Input

S

I0a

I1a

Za

I0b

I1b

Zb

GND

Za±Zd

Outputs

MC74AC157

MC74ACT157

QUAD 2-INPUT

MULTIPLEXER

N SUFFIX

CASE 648-08

PLASTIC

D SUFFIX

CASE 751B-05

PLASTIC

TRUTH TABLE

	Inputs			Outputs
E	S	I0	I1	Z
H	X	X	X	L
L	H	X	L	L
L	H	X	H	H
L	L	L	X	L
L	L	H	X	H

H = HIGH Voltage Level

L = LOW Voltage Level

X = Immaterial

LOGIC SYMBOL

E I0a I1a I0b I1b I0c I1c I0d I1d

S

Za

Zb

Zc

Zd

FACT DATA

5-1

MC74AC157 MC74ACT157

FUNCTIONAL DESCRIPTION

The MC74AC157/74ACT157 is a quad 2-input multiplexer. It selects four bits of data from two sources under the control of a common Select input (S). The Enable input (E) is active-LOW. When E is HIGH, all of the outputs (Z) are forced LOW regardless of all other inputs. The MC74AC157/ 74ACT157 is the logic implementation of a 4-pole, 2-position switch where the position of the switch is determined by the logic levels supplied to the Select input. The logic equations for the outputs are shown below:

Za = E•(I1a•S+I0a•S)

Zb = E•(I1b•S+I0b•S)

Zc = E•(I1c•S+I0c•S)

Zd = E•(I1d•S+I0d•S)

A common use of the MC74AC157/74ACT157 is the moving of data from two groups of registers to four common output busses. The particular register from which the data comes is determined by the state of the Select input. A less obvious use is as a function generator. The MC74AC157/ 74ACT157 can generate any four of the sixteen different functions of two variables with one variable common. This is useful for implementing gating functions.

LOGIC DIAGRAM

I0a

I1a

I0b

I1b

I0c

I1c

I0d

I1d

E

S

Za

Zb

Zc

Zd

Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.

MAXIMUM RATINGS*

Symbol	Parameter	Value	Unit
VCC	DC Supply Voltage (Referenced to GND)	±0.5 to +7.0	V
Vin	DC Input Voltage (Referenced to GND)	±0.5 to VCC +0.5	V
Vout	DC Output Voltage (Referenced to GND)	±0.5 to VCC +0.5	V
Iin	DC Input Current, per Pin	±20	mA
Iout	DC Output Sink/Source Current, per Pin	±50	mA
ICC	DC VCC or GND Current per Output Pin	±50	mA
Tstg	Storage Temperature	±65 to +150	°C

*Maximum Ratings are those values beyond which damage to the device may occur. Functional operation should be restricted to the Recommended Operating Conditions.

FACT DATA

5-2