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74AC257 • 74ACT257 Quad 2-Input Multiplexer with 3-STATE Outputs
November 1988
Revised November 1999
74AC257 • 74ACT257
Quad 2-Input Multiplexer with 3-STATE Outputs
General Description
The AC/ACT257 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 out-
puts present the selected data in true (noninverted) form.
The outputs may be switched to a high impedance state by
placing a logic HIGH on the common Output Enable (OE)
input, allowing the outputs to interface directly with bus-ori-
ented systems.
Features
s
I
CC
and I
OZ
reduced by 50%
s
Multiplexer expansion by tying outputs together
s
Noninverting 3-STATE outputs
s
Outputs source/sink 24 mA
s
ACT257 has TTL-compatible inputs
Ordering Code:
Order Number
74AC257SC
74AC257SJ
74AC257MTC
74AC257PC
74ACT257SC
74ACT257SJ
74ACT257MTC
74ACT257PC
Package Number
M16A
M16D
MTC16
N16E
M16A
M16D
MTC16
N16E
Package Description
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
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
IEEE/IEC
Pin Descriptions
Pin Names
S
OE
I
0a
–I
0d
I
1a
–I
1d
Z
a
–Z
d
Description
Common Data Select Input
3-STATE Output Enable Input
Data Inputs from Source 0
Data Inputs from Source 1
3-STATE Multiplexer Outputs
FACT is a trademark of Fairchild Semiconductor Corporation.
© 1999 Fairchild Semiconductor Corporation
DS009949
www.fairchildsemi.com
74AC257 • 74ACT257
Functional Description
The AC/ACT257 is quad 2-input multiplexer with 3-STATE
outputs. It selects four bits of data from two sources under
control of a Common Data Select input. When the Select
input is LOW, the I
0x
inputs are selected and when Select
is HIGH, the I
1x
inputs are selected. The data on the
selected inputs appears at the outputs in true (noninverted)
form. The device 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 as follows:
Z
a
=
OE • (1
1a
• S
+
I
0a
• S)
Z
b
=
OE • (1
1b
• S
+
I
0b
• S)
Z
c
=
OE • (1
1c
• S
+
I
0c
• S)
Z
d
=
OE • (1
1d
• S
+
I
0d
• S)
When the Output Enable (OE) is HIGH, the outputs are
forced to a high impedance state. If the outputs are tied
together, all but one device must be in the high impedance
state to avoid high currents that would exceed the maxi-
mum ratings. Designers should ensure the Output Enable
signals to 3-STATE devices whose outputs are tied
together are designed so there is no overlap.
Truth Table
Output
Enable
OE
H
L
L
L
L
H
=
HIGH Voltage Level
L
=
LOW Voltage Level
X
=
Immaterial
Z
=
High Impedance
Select
Input
S
X
H
H
L
L
I
0
X
X
X
L
H
Data
Inputs
I
1
X
L
H
X
X
Outputs
Z
Z
L
H
L
H
Logic Diagram
Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
www.fairchildsemi.com
2
74AC257 • 74ACT257
Absolute Maximum Ratings
(Note 1)
Supply Voltage (V
CC
)
DC Input Diode Current (I
IK
)
V
I
= −0.5V
V
I
=
V
CC
+0.5V
DC Input Voltage (V
I
)
DC Output Diode Current (I
OK
)
V
O
= −0.5V
V
O
=
V
CC
+0.5V
DC Output Voltage (V
O
)
DC Output Source ort
Sink Curren (I
O
)
DC V
CC
or Ground Current
Per Output Pin (I
CC
or I
GND
)
Storage Temperature (T
STG
)
Junction Temperature (T
J
)
PDIP
140°C
±50
mA
−65°C
to
+150°C
±50
mA
−20
mA
+20
mA
−0.5V
to V
CC
+
0.5V
−20
mA
+20
mA
−0.5V
to V
CC
+
0.5V
−0.5V
to
+7.0V
Recommended Operating
Conditions
Supply Voltage (V
CC
)
AC
ACT
Input Voltage (V
I
)
Output Voltage (V
O
)
Operating Temperature (T
A
)
Minimum Input Edge Rate (∆V/∆t)
AC Devices
V
IN
from 30% to 70% of V
CC
V
CC
@ 3.3V, 4.5V, 5.5V
Minimum Input Edge Rate (∆V/∆t)
ACT Devices
V
IN
from 0.8V to 2.0V
V
CC
@ 4.5V, 5.5V
125 mV/ns
Note 1:
Absolute maximum ratings are those values beyond which damage
to the device may occur. The databook specifications should be met, with-
out exception, to ensure that the system design is reliable over its power
supply, temperature, and output/input loading variables. Fairchild does not
recommend operation of FACT circuits outside databook specifications.
2.0V to 6.0V
4.5V to 5.5V
0V to V
CC
0V to V
CC
−40°C
to
+85°C
125 mV/ns
DC Electrical Characteristics for AC
Symbol
V
IH
Parameter
Minimum HIGH Level
Voltage Input
V
IL
Maximum LOW Level
Voltage Input
V
OH
Minimum HIGH Level
Voltage Output
V
CC
(V)
3.0
4.5
5.5
3.0
4.5
5.5
3.0
4.5
5.5
3.0
4.5
5.5
V
OL
Maximum LOW Level
Voltage Output
3.0
4.5
5.5
3.0
4.5
5.5
I
IN
(Note 4)
I
OZ
Maximum Input Leakage Current
Maximum 3-STATE
Leakage Current
I
OLD
I
OHD
I
CC
(Note 4)
Minimum Dynamic (Note 3)
Output Current
Maximum Quiescent Supply Current
5.5
5.5
5.5
5.5
4.0
±0.25
±2.5
75
−75
40.0
µA
mA
mA
µA
5.5
0.002
0.001
0.001
T
A
= +25°C
Typ
1.5
2.25
2.75
1.5
2.25
2.75
2.99
4.49
5.49
2.1
3.15
3.85
0.9
1.35
1.65
2.9
4.4
5.4
2.56
3.86
4.86
0.1
0.1
0.1
0.36
0.36
0.36
±
0.1
T
A
= −40°C
to
+85°C
Guaranteed Limits
2.1
3.15
3.85
0.9
1.35
1.65
2.9
4.4
5.4
V
IN
=
V
IL
or V
IH
2.46
3.76
4.76
0.1
0.1
0.1
V
IN
=
V
IL
or V
IH
0.44
0.44
0.44
±
1.0
µA
V
I
OL
=
12 mA
I
OL
=
24 mA
I
OL
=
24 mA (Note 2)
V
I
=
V
CC
, GND
V
I
(OE)
=
V
IL
, V
IH
V
I
=
V
CC
, GND
V
O
=
V
CC
, GND
V
OLD
=
1.65V Max
V
OHD
=
3.85V Min
V
IN
=
V
CC
or GND
V
I
OUT
=
50
µA
V
I
OH
= −12
mA
I
OH
= −24
mA
I
OH
= −24
mA (Note 2)
V
I
OUT
= −50 µA
V
V
OUT
=
0.1V
or V
CC
−
0.1V
V
Units
Conditions
V
OUT
=
0.1V
or V
CC
−
0.1V
Note 2:
All outputs loaded; thresholds on input associated with output under test.
Note 3:
Maximum test duration 2.0 ms, one output loaded at a time.
Note 4:
I
IN
and I
CC
@ 3.0V are guaranteed to be less than or equal to the respective limit @ 5.5V V
CC
.
3
www.fairchildsemi.com
74AC257 • 74ACT257
DC Electrical Characteristics for ACT
Symbol
V
IH
V
IL
V
OH
Parameter
Minimum HIGH Level
Input Voltage
Maximum LOW Level
Input Voltage
Minimum HIGH Level
Output Voltage
V
CC
(V)
4.5
5.5
4.5
5.5
4.5
5.5
4.5
5.5
V
OL
Maximum LOW Level
Output Voltage
4.5
5.5
4.5
5.5
I
IN
I
OZ
I
CCT
I
OLD
I
OHD
I
CC
Maximum Input
Leakage Current
Maximum 3-STATE
Leakage Current
Maximum
I
CC
/Input
Dynamic Output Current
Minimum (Note 6)
Maximum Quiescent
Supply Current
5.5
5.5
5.5
5.5
5.5
5.5
4.0
0.6
0.001
0.001
T
A
= +25°C
Typ
1.5
1.5
1.5
1.5
4.49
5.49
2.0
2.0
0.8
0.8
4.4
5.4
3.86
4.86
0.1
0.1
0.36
0.36
±0.1
±
0.5
T
A
= −40°C
to
+85°C
Guaranteed Limits
2.0
2.0
0.8
0.8
4.4
5.4
3.76
4.76
0.1
0.1
0.44
0.44
±1.0
±
5.0
1.5
75
−75
40.0
µA
µA
mA
mA
mA
µA
V
Units
V
V
V
Conditions
V
OUT
=
0.1V
or V
CC
−
0.1V
V
OUT
=
0.1V
or V
CC
−
0.1V
I
OUT
= −50 µA
V
IN
=
V
IL
or V
IH
V
I
OH
= −24
mA
I
OH
= −24
mA (Note 5)
I
OUT
=
50
µA
V
IN
=
V
IL
or V
IH
V
I
OL
=
24 mA
I
OL
=
24 mA (Note 5)
V
I
=
V
CC
, GND
V
I
=
V
IL
, V
IH
V
O
=
V
CC
, GND
V
I
=
V
CC
−
2.1V
V
OLD
=
1.65V Max
V
OHD
=
3.85V Min
V
IN
=
V
CC
or GND
Note 5:
All outputs loaded; thresholds on input associated with output under test.
Note 6:
Maximum test duration 2.0 ms, one output loaded at a time.
AC Electrical Characteristics for AC
V
CC
Symbol
Parameter
Propagation Delay
I
n
to Z
n
Propagation Delay
I
n
to Z
n
t
PLH
t
PHL
Propagation Delay
S to Z
n
Propagation Delay
S to Z
n
t
PZH
t
PZL
t
PHZ
t
PLZ
Output Enable Time
Output Enable Time
Output Disable Time
Output Disable Time
(V)
(Note 7)
t
PLH
t
PHL
3.3
5.0
3.3
5.0
3.3
5.0
3.3
5.0
3.3
5.0
3.3
5.0
3.3
5.0
3.3
5.0
Voltage Range 5.0 is 5.0V
±
0.5V
T
A
= +25°C
C
L
=
50 pF
Min
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
Typ
5.0
4.0
6.0
4.5
7.0
5.0
7.5
5.5
6.5
5.0
5.5
5.0
5.5
5.0
5.5
5.0
Max
8.5
6.0
8.5
6.0
10.5
7.5
10.5
7.5
9.5
7.5
9.0
8.5
10.0
9.0
9.0
8.0
T
A
= −40°C
to
+85°C
C
L
=
50 pF
Min
1.0
1.0
1.0
1.0
1.5
1.0
1.5
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Max
9.0
7.0
9.0
7.0
11.5
8.5
11.5
8.5
10.5
8.5
10.0
9.5
11.0
10.0
10.0
9.0
ns
ns
ns
ns
ns
ns
ns
ns
Units
Note 7:
Voltage Range 3.3 is 3.0V
±
0.3V
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4
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