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74AC251MTCX

P1-P3P4-P6P7-P9
© 1999 Fairchild Semiconductor Corporation DS009945 www.fairchildsemi.com
November 1988
Revised November 1999
74AC251 • 74ACT251 8-Input Multiplexer with 3-STATE Output
74AC251 • 74ACT251
8-Input Multiplexer with 3-STATE Output
General Description
The AC/ACT251 is a high-speed 8-input digital multiplexer.
It provides, in one package, the ability to select one bit of
data from up to eight sources. It can be used as universal
function generator to generate any logic function of four
variables. Both true and complementary outputs are pro-
vided.
Features
■ I
CC
reduced by 50%
■ Multifunctional capability
■ On-chip select logic decoding
■ Inverting and noninverting 3-STATE outputs
■ Outputs source/sink 24 mA
■ ACT251 has TTL-compatible inputs
Ordering Code:
Device also available in Tape and Reel. Specify by appending suffix letter “X” to the ordering code.
Logic Symbols
IEEE/IEC
Connection Diagram
Pin Descriptions
FACT is a trademark of Fairchild Semiconductor Corporation.
Order Number Package Number Package Description
74AC251SC M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150” Narrow Body
74AC251SJ M16D 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
74AC251MTC MTC16 16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
74AC251PC N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide
74ACT251SC M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150” Narrow Body
74ACT251MTC MTC16 16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
74ACT251PC N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide
Pin Names Description
S
0
–S
2
Select Inputs
OE
3-STATE Output Enable Input
I
0
–I
7
Multiplexer Inputs
Z 3-STATE Multiplexer Output
Z
Complementary 3-STATE Multiplexer Output
www.fairchildsemi.com 2
74AC251 • 74ACT251
Functional Description
This device is a logical implementation of a single-pole, 8-
position switch with the switch position controlled by the
state of three Select inputs, S
0
, S
1
, S
2
. Both true and com-
plementary outputs are provided. The Output Enable input
(OE
) is active LOW. When it is activated, the logic function
provided at the output is:
Z = OE
• (I
0
• S
0
• S
1
• S
2
+ I
1
• S
0
• S
1
• S
2
+
I
2
• S
0
• S
1
• S
2
+ I
3
• S
0
• S
1
• S
2
+
I
4
• S
0
• S
1
• S
2
+ I
5
• S
0
• S
1
• S
2
+
I
6
• S
0
• S
1
• S
2
+ I
7
• S
0
• S
1
• S
2
)
When the Output Enable is HIGH, both outputs are in the
high impedance (High Z) state. This feature allows multi-
plexer expansion by tying the outputs of up to 128 devices
together. When the outputs of the 3-STATE devices are
tied together, all but one device must be in the high imped-
ance state to avoid high currents that would exceed the
maximum ratings. The Output Enable signals should be
designed to ensure there is no overlap in the active-LOW
portion of the enable voltages.
Truth Table
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
Z = High Impedance
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.
Inputs Outputs
OE S
2
S
1
S
0
Z Z
H X X X Z Z
L L L LI
0
I
0
L L L HI
1
I
1
L L H LI
2
I
2
L L H HI
3
I
3
L H L L I
4
I
4
L H L HI
5
I
5
L H H L I
6
I
6
L H H HI
7
I
7
3 www.fairchildsemi.com
74AC251 • 74ACT251
Absolute Maximum Ratings(Note 1) Recommended Operating
Conditions
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.
DC Electrical Characteristics for AC
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
.
Supply Voltage (V
CC
) −0.5V to +7.0V
DC Input Diode Current (I
IK
)
V
I
= −0.5V −20 mA
V
I
= V
CC
+ 0.5V +20 mA
DC Input Voltage (V
I
) −0.5V to V
CC
+ 0.5V
DC Output Diode Current (I
OK
)
V
O
= −0.5V −20 mA
V
O
= V
CC
+ 0.5V +20 mA
DC Output Voltage (V
O
) −0.5V to V
CC
+ 0.5V
DC Output Source
or Sink Current (I
O
) ±50 mA
DC V
CC
or Ground Current
per Output Pin (I
CC
or I
GND
) ±50 mA
Storage Temperature (T
STG
) −65°C to +150°C
Junction Temperature (T
J
)
PDIP 140°C
Supply Voltage (V
CC
)
AC 2.0V to 6.0V
ACT 4.5V to 5.5V
Input Voltage (V
I
) 0V to V
CC
Output Voltage (V
O
) 0V to V
CC
Operating Temperature (T
A
) −40°C to +85°C
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 125 mV/ns
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
Symbol Parameter
V
CC
(V)
T
A
= +25°C T
A
= −40°C to +85°C
Units Conditions
Typ Guaranteed Limits
V
IH
Minimum HIGH Level 3.0 1.5 2.1 2.1 V
OUT
= 0.1V
Input Voltage 4.5 2.25 3.15 3.15 V or V
CC
− 0.1V
5.5 2.75 3.85 3.85
V
IL
Maximum LOW Level 3.0 1.5 0.9 0.9 V
OUT
= 0.1V
Input Voltage 4.5 2.25 1.35 1.35 V or V
CC
− 0.1V
5.5 2.75 1.65 1.65
V
OH
Minimum HIGH Level 3.0 2.99 2.9 2.9
Output Voltage 4.5 4.49 4.4 4.4 V I
OUT
= −50 µA
5.5 5.49 5.4 5.4
V
IN
= V
IL
or V
IH
3.0 2.56 2.46 I
OH
= −12 mA
4.5 3.86 3.76 V I
OH
= −24 mA
5.5 4.86 4.76 I
OH
= −24 mA (Note 2)
V
OL
Maximum LOW Level 3.0 0.002 0.1 0.1
Output Voltage 4.5 0.001 0.1 0.1 V I
OUT
= 50 µA
5.5 0.001 0.1 0.1
V
IN
= V
IL
or V
IH
3.0 0.36 0.44 I
OL
= 12 mA
4.5 0.36 0.44 V I
OL
= 24 mA
5.5 0.36 0.44 I
OL
= 24 mA (Note 2)
I
IN
(Note 4) Maximum Input Leakage Current 5.5 ±0.1 ±1.0 µAV
I
= V
CC
, GND
I
OZ
Maximum 3-STATE V
I
(OE) = V
IL
, V
IH
Current 5.5 ±0.25 ±2.5 µAV
I
= V
CC
, V
GND
V
O
= V
CC
, GND
I
OLD
Minimum Dynamic 5.5 75 mA V
OLD
= 1.65V Max
I
OHD
Output Current (Note 3) 5.5 −75 mA V
OHD
= 3.85V Min
I
CC
(Note 4) Maximum Quiescent Supply Curent 5.5 4.0 40.0 µAV
IN
= V
CC
or GND
P1-P3P4-P6P7-P9

74AC251MTCX

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MULTIPLEXER 8INPUT 3ST 16TSSOP
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