Datasheet

1. General description
The 74HC257; 74HCT257 are high-speed Si-gate CMOS devices and are pin compatible
with Low-power Schottky TTL (LSTTL).
The 74HC257 and 74HCT257 have four identical 2-input multiplexers with 3-state outputs,
which select 4 bits of data from two sources and are controlled by a common data select
input (S).
The data inputs from source 0 (1I0 to 4I0) are selected when input S is LOW and the data
inputs from source 1 (1I1 to 4I1) are selected when S is HIGH. Data appears at the
outputs (1Y to 4Y) in true (non-inverting) form from the selected inputs.
The 74HC257 and 74HCT257 are the logic implementation of a 4-pole, 2-position switch,
where the position of the switch is determined by the logic levels applied to S. The outputs
are forced to a high-impedance OFF-state when OE
is HIGH.
The logic equations for the outputs are:
Except for their non-inverting (true) outputs the 74HC257; 74HCT257 are identical to the
74HC258.
2. Features and benefits
 Non-inverting data path
 3-state outputs interface directly with system bus
 Complies with JEDEC standard no. 7A
 ESD protection:
 HBM JESD22-A114F exceeds 2000 V
 MM JESD22-A115-A exceeds 200 V
 Multiple package options
 Specified from 40 Cto+85C and from 40 Cto+125C
74HC257; 74HCT257
Quad 2-input multiplexer; 3-state
Rev. 6 — 26 January 2015 Product data sheet
1Y OE 1I1 S 1I0 S=
2Y OE 2I1 S 2I0 S=
3Y OE 3I1 S 3I0 S=
4Y OE 4I1 S 4I0 S=