Philips 74als251 DATASHEETS
INTEGRATED CIRCUITS
74ALS251
8–input multiplexer (3–State)
Product specification
IC05 Data Handbook
1991 Feb 08
Philips Semiconductors Product specification
74ALS2518-input multiplexer (3-State)
FEA TURES
•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
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.
TYPE
TYPICAL
PROPAGATION DELAY
74ALS251 7.0ns 7.5mA
) outputs are
TYPICAL
SUPPLY CURRENT
(TOTAL)
PIN CONFIGURATION
16
15
14
13
12
11
107
98GND S2
V
CC
I4
I5
I6
I7
S0
S1
OE
1
I3
2
I2
I1
3
I0
4
Y
5
6
Y
ORDERING INFORMA TION
ORDER CODE
DESCRIPTION COMMERCIAL RANGE
V
= 5V ±10%,
CC
T
= 0°C to +70°C
amb
16-pin plastic DIP 74ALS251N SOT38-4
16-pin plastic SO 74ALS251D SOT109-1
DRAWING
NUMBER
SC00066
INPUT AND OUTPUT LOADING AND FAN-OUT TABLE
PINS DESCRIPTION
I0 – I7 Data inputs 1.0/1.0 20µA/0.1mA
S0 – S2 Select inputs 1.0/1.0 20µA/0.1mA
OE Output Enable input (active-Low) 1.0/1.0 20µA/0.1mA
Y, Y Data outputs 130/240 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
11 S0
10 S1
9
7
VCC = Pin 16
GND = Pin 8
4 3 2 1 15 14 13
I0 I1 I2 I3 I4 I5 I6
S2
OE
YY
56
12
I7
SC00067
IEC/IEEE SYMBOL
74ALS (U.L.)
HIGH/LOW
7
11
10
9
4
3
2
1
15
14
13
12
EN
0
2
MUX
0
G
7
LOAD VALUE
HIGH/LOW
5
6
SC00068
1991 Feb 08 853–1377 01670
2
Philips Semiconductors Product specification
SYMBOL
PARAMETER
UNIT
74ALS2518-input multiplexer (3-State)
LOGIC DIAGRAM
9
S2
10
S1
11
S0
7
OE
I0 I1 I2 I3 I4 I5 I6 I7
4 3 2 1 15 14 13 12
FUNCTION TABLE
S2 S1 S0 OE Y Y
X X X H Z Z
L L L L I0 I0
L L H L I1 I1
L H L L I2 I2
L H H L I3 I3
H L L L I4 I4
H L H L I5 I5
H H L L I6 I6
H H H L I7 I7
H = High voltage level
L = Low voltage level
X = Don’t care
Z = High impedance “off” state
VCC = Pin 16
GND = Pin 8
56
YY
SC00069
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 –0.5 to +7.0 V
Input voltage –0.5 to +7.0 V
Input current –30 to +5 mA
Voltage applied to output in High output state –0.5 to V
Current applied to output in Low output state 48 mA
Operating free-air temperature range 0 to +70 °C
Storage temperature range –65 to +150 °C
PARAMETER RATING UNIT
INPUTS OUTPUTS
CC
V
RECOMMENDED OPERATING CONDITIONS
V
CC
V
V
I
IK
I
OH
I
OL
T
amb
1991 Feb 08
Supply voltage 4.5 5.0 5.5 V
High-level input voltage 2.0 V
IH
Low-level input voltage 0.8 V
IL
Input clamp current –18 mA
High-level output current –2.6 mA
Low-level output current 24 mA
Operating free-air temperature range 0 +70 °C
LIMITS
MIN NOM MAX
3
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