MC74ACT253MR1 View Datasheet(PDF) - ON Semiconductor

Part Name

Description

Manufacturer

MC74ACT253MR1

Dual 4-Input Multiplexer with 3-State Outputs

ON Semiconductor 

MC74AC253 MC74ACT253

FUNCTIONAL DESCRIPTION

The MC74AC253/74ACT253 contains two identical

4-input multiplexers with 3-state outputs. They select two bits

from four sources selected by common Select inputs (S0, S1).

The 4-input multiplexers have individual Output Enable (OEa,

OEb) inputs which, when HIGH, force the outputs to a high

impedance (High Z) state. This device is the logic

implementation of a 2-pole, 4-position 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:

Za = OEa•(I0a•S1•S0+I1a•S1•S0+

I2a•S1•S0+I3a•S1•S0)

Zb = OEb•(I0b•S1•S0+I1b•S1•S0+

I2b•S1•S0+I3b•S1•S0)

If the outputs of 3-state devices are tied together, all but one

device must be in the high impedance state to avoid high

currents that would exceed the maximum ratings. Designers

should ensure that Output Enable signals to 3-state devices

whose outputs are tied together are designed so that there is

no overlap.

OEb I3b

I2b

I1b

LOGIC DIAGRAM

I0b

S0

S1

I3a

I2a

I1a

I0a OEa

Zb

Za

Please note that this diagram is provided only for the understanding of logic

operations and should not be used to estimate propagation delays.

FACT DATA

5-2

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