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Fairchild Semiconductor |
November 1988
Revised November 1999
74ACT158
Quad 2-Input Multiplexer
General Description
The ACT158 is a high-speed quad 2-input multiplexer. It
selects four bits of data from two sources using the com-
mon Select and Enable inputs. The four buffered outputs
present the selected data in the inverted form. The ACT158
can also be used as a function generator.
Features
s ICC reduced by 50%
s Outputs source/sink 24 mA
s TTL-compatible inputs
Ordering Code:
Order Number Package Number
Package Description
74ACT158SC
74ACT158PC
74ACT158MTC
74ACT158SJ
M16A
M16D
MTC16
N16E
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150” Narrow Body
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide
Device also available in Tape and Reel. Specify by appending suffix letter “X” to the ordering code.
Logic Symbols
Connection Diagram
IEE/IEC
Pin Descriptions
Pin Names
Description
I0a–I0d
I1a–I1d
E
Source 0 Data Inputs
Source 1 Data Inputs
Enable Input
S Select Input
Za–Zd
Inverted Outputs
FACT is a trademark of Fairchild Semiconductor Corporation.
© 1999 Fairchild Semiconductor Corporation DS009930
www.fairchildsemi.com
Functional Description
The ACT158 quad 2-input multiplexer selects four bits of
data from two sources under the control of a common
Select input (S) and presents the data in inverted form at
the four outputs. The Enable input (E) is active-LOW. When
E is HIGH, all of the outputs (Z) are forced HIGH regard-
less of all other inputs. The ACT158 is the logic implemen-
tation of a 4-pole, 2-position switch where the position of
the switch is determined by the logic levels supplied to the
Select input.
A common use of the ACT158 is the moving of data from
two groups of registers to four common output busses. The
particular register from which the data comes is determined
by the state of the Select input. A less obvious use is as a
function generator. The ACT158 can generate four func-
tions of two variables with one variable common. This is
useful for implementing gating functions.
Logic Diagram
Truth Table
Inputs
ES
HX
I0
X
LL
L
LL
H
LH
X
LH
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
X
Outputs
I1 Z
XH
XH
XL
LH
HL
Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
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