Motorola MC74ACT253N Datasheet
5-1
FACT DATA
The MC74AC253/74ACT253 is a dual 4-input multiplexer with 3-state outputs. It
can select two bits of data from four sources using common select inputs. The
outputs may be individually switched to a high impedance state with a HIGH on the
respective Output Enable (OE
) inputs, allowing the outputs to interface directly with
bus oriented systems.
• Multifunctional Capability
• Noninverting 3-State Outputs
• Outputs Source/Sink 24 mA
• ′ACT253 Has TTL Compatible Inputs
1516 14 13 12 11 10
21 3 4 5 6
7
V
CC
9
8
OE
bS0I3bI2bI1bI0bZb
OE
aS1I3aI2aI1aI0aZa
GND
PIN NAMES
I0a–I
3a
Side A Data Inputs
I0b–I
3b
Side B Data Inputs
S0, S1Common Select Inputs
OE
a
Side A Output Enable Input
OE
b
Side B Output Enable Input
Za, Z
b
3-State Outputs
TRUTH TABLE
Select
Inputs
Data Inputs
Output
Enable
Outputs
S
0
S
1I0
I
1
I
2
I
3
OE Z
X X X X X X H Z
L L L X X X L L
L L H X X X L H
H L X L X X L L
H L X H X X L H
L H X X L X L L
L H X X H X L H
H H X X X L L L
H H X X X H L H
Address inputs S0 and S1 are common to both sections.
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
Z = High Impedance
DUAL 4-INPUT
MULTIPLEXER WITH
3-STATE OUTPUTS
N SUFFIX
CASE 648-08
PLASTIC
D SUFFIX
CASE 751B-05
PLASTIC
LOGIC SYMBOL
S
0
S
1
OEaI0aI1aI2aI
3a
Z
a
Z
b
I0bI1bI2bI3bOE
b
MC74AC253 MC74ACT253
5-2
FACT DATA
FUNCTIONAL DESCRIPTION
The MC74AC253/74ACT253 contains two identical
4-input multiplexers with 3-state outputs. They select two bits
from four sources selected by common Select inputs (S0, S1).
The 4-input multiplexers have individual Output Enable (OE
a
,
OE
b
) inputs which, when HIGH, force the outputs to a high
impedance (High Z) state. This device is the logic
implementation of a 2-pole, 4-position switch, where the
position of the switch is determined by the logic levels supplied
to the two select inputs. The logic equations for the outputs are
shown:
Za = OE
a
•(I0a•S1•S
0+I1a•S1
•S
0
+
I
2a
•S1•S
0+I3a
•S1•S
0
)
Zb = OE
b
•(I0b•S1•S
0+I1b•S1
•S
0
+
I
2b
•S1•S
0+I3b
•S1•S
0
)
If the outputs of 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 that there is
no overlap.
OEbI
3b
I
2b
I
1b
I
0b
S
0
S
1
I
3a
I
2a
Z
b
Z
a
I
1a
I
0a
OE
a
Please note that this diagram is provided only for the understanding of logic
operations and should not be used to estimate propagation delays.
LOGIC DIAGRAM
MC74AC253 MC74ACT253
5-3
FACT DATA
MAXIMUM RATINGS*
Symbol Parameter Value Unit
V
CC
DC Supply Voltage (Referenced to GND) –0.5 to +7.0 V
V
in
DC Input Voltage (Referenced to GND) –0.5 to VCC +0.5 V
V
out
DC Output Voltage (Referenced to GND) –0.5 to VCC +0.5 V
I
in
DC Input Current, per Pin ±20 mA
I
out
DC Output Sink/Source Current, per Pin ±50 mA
I
CC
DC VCC or GND Current per Output Pin ±50 mA
T
stg
Storage Temperature –65 to +150 °C
* Maximum Ratings are those values beyond which damage to the device may occur. Functional operation should be restricted to the Recommended
Operating Conditions.
RECOMMENDED OPERATING CONDITIONS
Symbol Parameter Min Typ Max Unit
′AC 2.0 5.0 6.0
VCCSupply Voltage
′ACT 4.5 5.0 5.5
V
Vin, V
out
DC Input Voltage, Output Voltage (Ref. to GND) 0 V
CC
V
VCC @ 3.0 V 150
Input Rise and Fall Time (Note 1)
′AC Devices except Schmitt Inputs
VCC @ 4.5 V 40 ns/V
r
, t
f
′AC Devices except Schmitt Inputs
VCC @ 5.5 V 25
VCC @ 4.5 V 10
tr, t
f
Input Rise and Fall Time (Note 2)
′ACT Devices except Schmitt Inputs
VCC @ 5.5 V 8.0
ns/V
T
J
Junction Temperature (PDIP) 140 °C
T
A
Operating Ambient Temperature Range –40 25 85 °C
I
OH
Output Current — High –24 mA
I
OL
Output Current — Low 24 mA
1. Vin from 30% to 70% VCC; see individual Data Sheets for devices that differ from the typical input rise and fall times.
2. Vin from 0.8 V to 2.0 V; see individual Data Sheets for devices that differ from the typical input rise and fall times.
tr, t
f
Input Rise and Fall Time (Note 2)
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