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Fairchild Semiconductor |
November 1988
Revised November 1999
74ACT258
Quad 2-Input Multiplexer with 3-STATE Outputs
General Description
The ACT258 is a quad 2-input multiplexer with 3-STATE
outputs. Four bits of data from two sources can be selected
using a common data select input. The four outputs
present the selected data in the complement (inverted)
form. The outputs may be switched to a high impedance
state with a HIGH on the common Output Enable (OE)
input, allowing the outputs to interface directly with bus-ori-
ented systems.
Features
s ICC and IOZ reduced by 50%
s Multiplexer expansion by tying outputs together
s Inverting 3-STATE outputs
s Outputs source/sink 24 mA
s TTL-compatible inputs
Ordering Code:
Order Number Package Number
Package Description
74ACT258SC
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150” Narrow Body
74ACT258SJ
M16D
16-Lead Small Outline Package (SOP), EIAJ TYPE 11, 5.3mm Wide
74ACT258MTC
MTC16
16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
74ACT258PC
N16E
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
IEEE/IEC
Pin Descriptions
Pin Names
S
OE
I0a–I0d
I1a–I1d
Za–Zd
Description
Common Data Select Input
3-STATE Output Enable Input
Data Inputs from Source 0
Data Inputs from Source 1
3-STATE Inverting Data Outputs
FACT is a trademark of Fairchild Semiconductor Corporation.
© 1999 Fairchild Semiconductor Corporation DS009950
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Truth Table
Output
Enable
OE
H
L
L
Select
Input
S
X
H
H
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
Z = High Impedance
Logic Diagram
Data
Inputs
I0 I1
XX
XL
XH
Outputs
Z
Z
H
L
Functional Description
The ACT258 is a quad 2-input multiplexer with 3-STATE
outputs. It selects four bits of data from two sources under
control of a common Select input (S). When the Select
input is LOW, the I0x inputs are selected and when Select
is HIGH, the I1x inputs are selected. The data on the
selected inputs appears at the outputs in inverted form.
The ACT258 is the logic implementation of a 4-pole, 2-
position switch where the position of the switch is deter-
mined by the logic levels supplied to the Select input. The
logic equations for the outputs are shown below:
Za = OE • (I1a • S + I0a • S)
Zb = OE • (I1b • S + I0b • S)
Zc = OE • (I1c • S + I0c • S)
Zd = OE • (I1d • S + I0d • S)
When the Output Enable input (OE) is HIGH, the outputs
are forced to a high impedance state. If the outputs of the
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 there is
no overlap.
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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