Philips Semiconductors Product specification
74F251A8-input multiplexer (3-State)
11996 Jan 05 853–0358 16191
FEATURES
• High speed 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 74F251A 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 output
connections to a common bus without driving nor loading the bus
significantly. All but one device must be in High impedance state to
avoid high currents that would exceed the maximum ratings when
the outputs of the 3-State devices are tied together. When the output
of more than one device is tied together the user must ensure that
there is no overlap in the active Low portion of the output enable
voltages.
PIN CONFIGURATION
16
15
14
13
12
11
107
6
5
4
3
2
1
OE
V
CC
I7
S0
S1
I6
I4
I5
I3
I2
Y
I1
I0
Y
98GND S2
SF00778
TYPE
TYPICAL
PROPAGATION
DELAY
TYPICAL
SUPPLY CURRENT
(TOTAL)
74F251A 4.5ns 19mA
ORDERING INFORMATION
DESCRIPTION
ORDER CODE
PKG
COMMERCIAL RANGE
V
CC
= 5V ±10%,
T
amb
= 0°C to +70°C
DWG #
16-pin plastic DIP N74F251AN SOT38-4
16-pin plastic SO N74F251AD SOT162-1
INPUT AND OUTPUT LOADING AND FAN-OUT TABLE
PINS DESCRIPTION 74F (U.L.) HIGH/LOW LOAD VALUE HIGH/LOW
I0–I7 Data inputs 1.0/1.0 20µA/0.6mA
S0–S2 Select inputs 1.0/1.0 20µA/0.6mA
OE Output Enable input (active Low) 1.0/1.0 20µA/0.6mA
Y, Y Data outputs 150/40 3mA/24mA
NOTE:
One (1.0) FAST unit load is defined as: 20µA in the High state and 0.6mA in the Low state.
LOGIC SYMBOL
123
V
CC
= Pin 16
GND = Pin 8
SF00779
65
11
10
9
S0
S1
S2
7
4 12131415
OE
YY
I0 I1 I2 I3 I4 I5 I6 I7
IEC/IEEE SYMBOL
SF00780
MUX7
11
3
2
1
5
6
0
G
0
7
10
2
EN
9
4
14
13
12
15