TECHNICAL DATA
IN74AC257
Quad 2-Input Data Selector/Multiplexer
with 3-State Outputs
High-Speed Silicon-Gate CMOS
The IN74AC257 is identical in pinout to the LS/ALS257,
HC/HCT257. The device inputs are compatible with standard CMOS
outputs; with pullup resistors, they are compatible with LS/ALS
outputs.
This device selects a (4-bit) nibble from either the A or B inputs as
determined by the Select input. The nibble is presented at the outputs
in noninverted from when the Output Enable pin is at a low level. A
high level on the Output Enable pin switches the outputs into the high-
impedance state.
ORDERING INFORMATION
IN74AC257N Plastic
IN74AC257D SOIC
TA = -40° to 85° C for all
packages
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Outputs Directly Interface to CMOS, NMOS, and TTL
Operating Voltage Range: 2.0 to 6.0 V
Low Input Current: 1.0 µA; 0.1 µA @ 25°C
High Noise Immunity Characteristic of CMOS Devices
Output Source/Sink 24 mA
PIN ASSIGNMENT
LOGIC DIAGRAM
FUNCTION TABLE
Inputs
Output
Outputs
Y0-Y3
Select
Enable
H
X
L
Z
L
L
A0-A3
B0-B3
H
X=don’t care
Z = high-impedance state
PIN 16 =VCC
PIN 8 = GND
A0-A3,B0-B3=the levels of the respective
Nibble Inputs
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