INTEGRATED CIRCUITS
74ALS251
8–input multiplexer (3–State)
Product specification
IC05 Data Handbook
1991 Feb 08
Philips
Semiconductors
Philips Semiconductors
Product specification
8-input multiplexer (3-State)
74ALS251
FEATURES
•
8-to-1 multiplexing
•
On chip decoding
•
Multifunction capability
•
Inverting and non-inverting outputs
•
Both outputs are 3-State for further multiplexer expansion
DESCRIPTION
The 74ALS251 is a logic implementation of a single 8-position
switch with the switch position controlled by the state of three select
(S0, S1, S2) inputs. True (Y) and complementary (Y) outputs are
both provided.
The output enable (OE) is active Low. When OE is High, both
outputs are in High impedance state, allowing multiple connections
to a common bus without driving nor loading the bus significantly.
When the outputs of more than one device are tied together, the
user must ensure that there is no overlap in the active-Low portion
of the output enable voltages in order to avoid high currents that
could exceed the maximum current rating.
TYPICAL
SUPPLY CURRENT
(TOTAL)
7.5mA
PIN CONFIGURATION
I3
I2
I1
I0
Y
Y
OE
GND
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
CC
I4
I5
I6
I7
S0
S1
S2
SC00066
ORDERING INFORMATION
ORDER CODE
DESCRIPTION
COMMERCIAL RANGE
V
CC
= 5V
±10%,
T
amb
= 0°C to +70°C
74ALS251N
74ALS251D
DRAWING
NUMBER
TYPE
74ALS251
TYPICAL
PROPAGATION DELAY
7.0ns
16-pin plastic DIP
16-pin plastic SO
SOT38-4
SOT109-1
INPUT AND OUTPUT LOADING AND FAN-OUT TABLE
PINS
I0 – I7
S0 – S2
OE
Y, Y
Data inputs
Select inputs
Output Enable input (active-Low)
Data outputs
DESCRIPTION
74ALS (U.L.)
HIGH/LOW
1.0/1.0
1.0/1.0
1.0/1.0
130/240
LOAD VALUE
HIGH/LOW
20µA/0.1mA
20µA/0.1mA
20µA/0.1mA
2.5mA/24mA
NOTE:
One (1.0) ALS unit load is defined as: 20µA in the High state and 0.1mA in the Low state.
LOGIC SYMBOL
4
3
2
1
15
14
13
12
IEC/IEEE SYMBOL
7
EN
11
0
10
I0
I1
I2
I3
I4
I5
I6
I7
9
2
4
3
2
1
6
Y
Y
15
14
5
6
13
12
G
0
7
5
MUX
11
10
9
7
S0
S1
S2
OE
V
CC
= Pin 16
GND = Pin 8
SC00067
SC00068
1991 Feb 08
2
853–1377 01670
Philips Semiconductors
Product specification
8-input multiplexer (3-State)
74ALS251
LOGIC DIAGRAM
I0
4
9
10
11
7
I1
3
I2
2
I3
1
I4
15
I5
14
I6
13
I7
12
FUNCTION TABLE
INPUTS
S2
X
L
L
L
L
H
H
H
H
H
L
X
Z
SC00069
OUTPUTS
S0
X
L
H
L
H
L
H
L
H
OE
H
L
L
L
L
L
L
L
L
Y
Z
I0
I1
I2
I3
I4
I5
I6
I7
Y
Z
I0
I1
I2
I3
I4
I5
I6
I7
S1
X
L
L
H
H
L
L
H
H
S2
S1
S0
OE
5
V
CC
= Pin 16
GND = Pin 8
Y
Y
6
=
=
=
=
High voltage level
Low voltage level
Don’t care
High impedance “off” state
ABSOLUTE MAXIMUM RATINGS
(Operation beyond the limit set forth in this table may impair the useful life of the device.
Unless otherwise noted these limits are over the operating free air temperature range.)
SYMBOL
V
CC
V
IN
I
IN
V
OUT
I
OUT
T
amb
T
stg
Supply voltage
Input voltage
Input current
Voltage applied to output in High output state
Current applied to output in Low output state
Operating free-air temperature range
Storage temperature range
PARAMETER
RATING
–0.5 to +7.0
–0.5 to +7.0
–30 to +5
–0.5 to V
CC
48
0 to +70
–65 to +150
UNIT
V
V
mA
V
mA
°C
°C
RECOMMENDED OPERATING CONDITIONS
LIMITS
SYMBOL
V
CC
V
IH
V
IL
I
IK
I
OH
I
OL
T
amb
Supply voltage
High-level input voltage
Low-level input voltage
Input clamp current
High-level output current
Low-level output current
Operating free-air temperature range
0
PARAMETER
MIN
4.5
2.0
0.8
–18
–2.6
24
+70
NOM
5.0
MAX
5.5
UNIT
V
V
V
mA
mA
mA
°C
1991 Feb 08
3
Philips Semiconductors
Product specification
8-input multiplexer (3-State)
74ALS251
DC ELECTRICAL CHARACTERISTICS
(Over recommended operating free-air temperature range unless otherwise noted.)
SYMBOL
PARAMETER
TEST CONDITIONS
1
V
CC
±10%,
V
IL
= MAX,
,
,
V
IH
= MIN
V
CC
= MIN, V
IL
= MAX,
,
,
V
IH
= MIN
V
CC
= MIN, I
I
= I
IK
V
CC
= MAX, V
I
= 7.0V
V
CC
= MAX, V
I
= 2.7V
V
CC
= MAX, V
I
= 0.4V
V
CC
= MAX, V
I
= 2.7V
V
CC
= MAX, V
I
= 0.4V
V
CC
= MAX, V
O
= 2.25V
I
CC
I
CCZ
V
CC
= MAX
–30
7.0
9.0
I
OH
= –0.4mA
I
OH
= –2.6mA
I
OL
= 12mA
I
OL
= 24mA
LIMITS
MIN
V
CC
– 2
2.4
3.2
0.25
0.35
–0.73
0.40
0.50
–1.5
0.1
20
–0.1
20
–20
–112
10
14
TYP
2
MAX
UNIT
V
V
V
V
V
mA
µA
mA
µA
µA
mA
mA
mA
V
O
OH
High-level
High level output voltage
V
O
OL
V
IK
I
I
I
IH
I
IL
I
OZH
I
OZL
I
O
I
CC
Low-level
Low level output voltage
Input clamp voltage
Input current at maximum input voltage
High-level input current
Low-level input current
Off-state output current,
High-level voltage applied
Off-state output current,
Low-level voltage applied
Output current
3
Supply current (total)
NOTES:
1. For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions for the applicable type.
2. All typical values are at V
CC
= 5V, T
amb
= 25°C.
3. The output conditions have been chosen to produce a current that closely approximates one half of the true short-circuit output current, I
OS
.
AC ELECTRICAL CHARACTERISTICS
LIMITS
SYMBOL
PARAMETER
TEST CONDITION
T
amb
= 0°C to +70°C
V
CC
= +5.0V
±
10%
C
L
= 50pF, R
L
= 500Ω
MIN
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
t
PZH
t
PZL
t
PHZ
t
PLZ
t
PZH
t
PZL
t
PHZ
t
PLZ
Propagation delay
In to Y
Propagation delay
In to Y
Propagation delay
Sn to Y
Propagation delay
Sn to Y
Propagation delay
OE to Y
Propagation delay
OE to Y
Propagation delay
OE to Y
Propagation delay
OE to Y
Waveform 2
Waveform 1
Waveform 1, 2
Waveform 1, 2
Waveform 3
Waveform 4
Waveform 3
Waveform 4
Waveform 3
Waveform 4
Waveform 3
Waveform 4
4.0
4.0
3.0
6.0
5.0
7.0
8.0
5.0
2.0
3.0
2.0
1.0
2.0
3.0
2.0
1.0
MAX
12.0
12.0
10.0
15.0
15.0
16.0
17.0
15.0
8.0
9.0
8.0
7.0
8.0
9.0
8.0
7.0
ns
ns
ns
ns
ns
ns
ns
ns
UNIT
1991 Feb 08
4
Philips Semiconductors
Product specification
8-input multiplexer (3-State)
74ALS251
AC WAVEFORMS
For all waveforms, V
M
= 1.3V.
V
IN
V
IN
V
M
t
PHL
V
M
t
PLH
V
M
t
PLH
V
M
t
PHL
V
OUT
V
M
V
M
V
OUT
V
M
V
M
SF00093
SF00092
Waveform 1. Propagation Delay for Inverting Output
Waveform 2. Propagation Delay for Non-inverting Output
OE
V
M
t
PZH
V
M
t
PHZ
V
M
0V
V
OH
-0.3V
OE
V
M
t
PZL
V
M
t
PLZ
3.5V
V
M
V
OL
+0.3V
Y, Y
Y, Y
SC00070
SC00071
Waveform 3. 3-State Output Enable Time to High Level
and Output Disable Time from High Level
Waveform 4. 3-State Output Enable Time to Low Level
and Output Disable Time from Low Level
TEST CIRCUIT AND WAVEFORMS
V
CC
7.0V
NEGATIVE
PULSE
90%
V
M
10%
t
THL (
t
f
f
)
C
L
R
L
t
w
V
M
10%
t
TLH (
t
r
)
0.3V
90%
AMP (V)
V
IN
PULSE
GENERATOR
R
T
D.U.T.
V
OUT
R
L
t
TLH (
t
r
)
90%
t
THL (
t
f
)
AMP (V)
90%
V
M
t
w
10%
0.3V
Test Circuit for 3-State Outputs
SWITCH POSITION
TEST
SWITCH
closed
t
PLZ
, t
PZL
All other
open
POSITIVE
PULSE
10%
V
M
Input Pulse Definition
INPUT PULSE REQUIREMENTS
Family
Amplitude V
M
74ALS
3.5V
1.3V
Rep.Rate
1MHz
t
w
500ns
t
TLH
2.0ns
t
THL
2.0ns
DEFINITIONS:
R
L
= Load resistor;
see AC electrical characteristics for value.
C
L
= Load capacitance includes jig and probe capacitance;
see AC electrical characteristics for value.
R
T
= Termination resistance should be equal to Z
OUT
of
pulse generators.
SC00072
1991 Feb 08
5
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