5-258

FAST AND LS TTL DATA

SN54/74LS153

FUNCTIONAL DESCRIPTION

The LS153 is a Dual 4-input Multiplexer fabricated with Low

Power, Schottky barrier diode process for high speed. It can

select two bits of data from up to four sources under the control

of the common Select Inputs (S0, S1). The two 4-input multi-

plexer circuits have individual active LOW Enables (Ea, Eb)

which can be used to strobe the outputs independently. When

the Enables (Ea, Eb) are HIGH, the corresponding outputs (Za,

Zb) are forced LOW.

The LS153 is the logic implementation of a 2-pole, 4-posi-

tion switch, where the position of the switch is determined by

the logic levels supplied to the two Select Inputs. The logic

equations for the outputs are shown below.

Za = Ea ⋅ (I0a ⋅ S1 ⋅ S0 + I1a ⋅ S1 ⋅ S0 + I2a ⋅ S1 ⋅ S0 +

I3a ⋅ S1 ⋅ S0)

Zb = Eb ⋅ (I0b ⋅ S1 ⋅ S0 + I1b ⋅ S1 ⋅ S0 + I2b ⋅ S1 ⋅ S0 +

I3b ⋅ S1 ⋅ S0)

The LS153 can be used to move data from a group of regis-

ters to a common output bus. The particular register from

which the data came would be determined by the state of the

Select Inputs. A less obvious application is a function genera-

tor. The LS153 can generate two functions of three variables.

This is useful for implementing highly irregular random logic.

TRUTH TABLE

SELECT INPUTS

INPUTS (a or b)

OUTPUT

S0

S1

E

I0

I1

I2

I3

Z

X

X

H

X

X

X

X

L

L

L

L

L

X

X

X

L

L

L

L

H

X

X

X

H

H

L

L

X

L

X

X

L

H

L

L

X

H

X

X

H

L

H

L

X

X

L

X

L

L

H

L

X

X

H

X

H

H

H

L

X

X

X

L

L

H

H

L

X

X

X

H

H

H = HIGH Voltage Level

L = LOW Voltage Level

X = Don’t Care

GUARANTEED OPERATING RANGES

Symbol

Parameter

Min

Typ

Max

Unit

VCC

Supply Voltage

54

74

4.5

4.75

5.0

5.0

5.5

5.25

V

TA

Operating Ambient Temperature Range

54

74

– 55

0

25

25

125

70

°C

IOH

Output Current — High

54, 74

– 0.4

mA

IOL

Output Current — Low

54

74

4.0

8.0

mA