TECHNICAL DATA
IN74ACT257
Quad 2-Input Data Selector/Multiplexer
with 3-State Outputs
High-Speed Silicon-Gate CMOS
The IN74ACT257 is identical in pinout to the LS/ALS257,
HC/HCT257. The IN74ACT257 may be used as a level converter for
interfacing TTL or NMOS outputs to High Speed CMOS inputs.
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
IN74ACT257N Plastic
IN74ACT257D SOIC
TA = -40° to 85° C for all packages
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TTL/NMOS Compatible Input Levels
Outputs Directly Interface to CMOS, NMOS, and TTL
Operating Voltage Range: 4.5 to 5.5 V
Low Input Current: 1.0 µA; 0.1 µA @ 25°C
Outputs 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
Rev. 00