74ALS251 データシートの表示（PDF） - Philips Electronics
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74ALS251 Datasheet PDF : 8 Pages
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Philips Semiconductors
8-input multiplexer (3-State)
Product specification
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.
TYPE
TYPICAL
PROPAGATION DELAY
74ALS251
7.0ns
TYPICAL
SUPPLY CURRENT
(TOTAL)
7.5mA
PIN CONFIGURATION
I3 1
I2 2
I1 3
I0 4
Y5
Y6
OE 7
GND 8
16 VCC
15 I4
14 I5
13 I6
12 I7
11 S0
10 S1
9 S2
SC00066
ORDERING INFORMATION
ORDER CODE
DESCRIPTION
COMMERCIAL RANGE
VCC = 5V ±10%,
Tamb = 0°C to +70°C
16-pin plastic DIP
74ALS251N
16-pin plastic SO
74ALS251D
DRAWING
NUMBER
SOT38-4
SOT109-1
INPUT AND OUTPUT LOADING AND FAN-OUT TABLE
PINS
DESCRIPTION
74ALS (U.L.)
HIGH/LOW
I0 – I7
Data inputs
1.0/1.0
S0 – S2
Select inputs
1.0/1.0
OE
Output Enable input (active-Low)
1.0/1.0
Y, Y
Data outputs
130/240
NOTE: One (1.0) ALS unit load is defined as: 20µA in the High state and 0.1mA in the Low state.
LOGIC SYMBOL
IEC/IEEE SYMBOL
11
10
9
7
VCC = Pin 16
GND = Pin 8
4 3 2 1 15 14 13 12
I0 I1 I2 I3 I4 I5 I6 I7
S0
S1
S2
OE
YY
56
SC00067
7
EN MUX
11
0
10
9
G
0
7
2
4
3
2
1
15
14
13
12
LOAD VALUE
HIGH/LOW
20µA/0.1mA
20µA/0.1mA
20µA/0.1mA
2.5mA/24mA
5
6
SC00068
1991 Feb 08
2
853–1377 01670
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