MC74F257A
QUAD 2-INPUT MULTIPLEXER
WITH 3-STATE OUTPUTS
The MC74F257 is a quad 2-input multiplexer with 3-state outputs. Four bits
of data from two sources can be selected using a common Data Select input.
The four outputs present the selected data in true (non-inverted) form. The
outputs may be switched to a high impedance state with a HIGH on the com-
mon Output Enable (OE) input, allowing the outputs to interface directly with
bus oriented systems.
•
Multiplexer Expansion by Tying Outputs Together
•
Non-Inverting 3-State Outputs
•
Input Clamp Diodes Limit High-Speed Termination Effects
•
AC Enhanced Version of the F257
CONNECTION DIAGRAM
VCC
16
OE
15
I0c
14
I1c
13
Zc
12
I0d
11
I1d
10
Zd
9
16
1
QUAD 2-INPUT MULTIPLEXER
WITH 3-STATE OUTPUTS
FAST™ SCHOTTKY TTL
J SUFFIX
CERAMIC
CASE 620-09
16
N SUFFIX
PLASTIC
CASE 648-08
1
1
S
2
I0a
3
I1a
4
Za
5
I0b
6
I1b
7
Zb
8
GND
LOGIC DIAGRAM
OE
I0a
I1a
I0b
I1b
I0c
I1c
I0d
I1d
S
16
1
D SUFFIX
SOIC
CASE 751B-03
ORDERING INFORMATION
MC54FXXXAJ Ceramic
MC74FXXXAN Plastic
MC74FXXXAD SOIC
LOGIC SYMBOL
1
Za
Zb
Zc
Zd
4
Za
Zb
Zc
Zd
S
OE
I0a
I1a
I0b
I1b
I0c
I1c
I0d
I1d
15
2
3
5
6
14
13
11
10
FUNCTION TABLE
Output
Enable
OE
H
L
L
L
L
Select
Input
S
X
H
H
L
L
Data
Inputs
I0
X
X
X
L
H
I1
X
L
H
X
X
Outputs
Z
Z
L
H
L
H
H = HIGH Voltage Level
L = LOW Voltage Level
X = Don’t Care
Z = High Impedance
7
12
9
VCC = PIN 16
GND = PIN 8
FAST AND LS TTL DATA
4-127
MC74F257A
GUARANTEED OPERATING RANGES
Symbol
VCC
TA
IOH
IOL
Supply Voltage
Operating Ambient Temperature Range
Output Current — High
Output Current — Low
Parameter
74
74
74
74
Min
4.5
0
Typ
5.0
25
Max
5.5
70
–3.0
24
Unit
V
°C
mA
mA
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE
(unless otherwise specified)
Limits
Symbol
VIH
VIL
VIK
VOH
Parameter
Input HIGH Voltage
Input LOW Voltage
Input Clamp Diode Voltage
Output HIGH Voltage
74
74
VOL
IOZH
IOZL
IIH
Output LOW Voltage
Output OFF Current — HIGH
Output OFF Current — LOW
Input HIGH Current
2.4
2.7
3.3
3.3
0.35
0.5
50
–50
20
100
IIL
IOS
ICCH
Input LOW Current
Output Short Circuit Current (Note 2)
–60
9.0
–0.6
–150
15
mA
mA
Min
2.0
0.8
–1.2
Typ
Max
Unit
V
V
V
V
V
V
µA
µA
µA
Test Conditions
Guaranteed Input HIGH Voltage
Guaranteed Input LOW Voltage
IIN = –18 mA
IOH = –3.0 mA
IOH = –3.0 mA
IOL = 24 mA
VOUT = 2.7 V
VOUT = 0.5 V
VIN = 2.7 V
VIN = 7.0 V
VIN = 0.5 V
VOUT = 0 V
S, I1x = 4.5 V
OE, I0x = GND
ICCL
Power Supply Current
14.5
22
mA
I1x = 4.5 V
OE, I0x, S = GND
ICCZ
15
23
S, I0x = GND
OE, I1x = 4.5 V
NOTES:
1. For conditions shown as MIN or MAX, use the appropriate value specified under guaranteed operating ranges.
2. Not more than one output should be shorted at a time, nor for more than 1 second.
VCC = MIN
VCC = 4.50 V
VCC = 4.75 V
VCC = MIN
VCC = MAX
VCC = MAX
VCC = MAX
VCC = MAX
VCC = MAX
VCC = MAX
FUNCTIONAL DESCRIPTION
The F257A is a quad 2-input multiplexer with 3-state out-
puts. It selects four bits of data from two sources under control
of a Common Data Select input. When the Select input is
LOW, the I0x inputs are selected and when Select is HIGH, the
I1x inputs are selected. The data on the selected inputs ap-
pears at the outputs in true (non-inverted) form. The device is
the logic implementation of a 4-pole, 2-position switch where
the position of the switch is determined by the logic levels sup-
plied to the Select input. The logic equations for the outputs are
shown below:
Za = OE
•
(I
1a
•
S + I0a
•
S)
Zb = OE
•
(I1b
•
S + I0b
•
S)
Zc = OE
•
(I1c
•
S + I0c
•
S)
Zd = OE
•
(I1d
•
S + I0d
•
S)
When the Output Enable input (OE) is HIGH, the outputs are
forced to a high impedance OFF state. If the outputs are tied
together, all but one device must be in the high impedance
state to avoid high currents that would exceed the maximum
ratings. Designers should ensure the Output Enable signals to
3-state devices whose outputs are tied together are designed
so there is no overlap.
FAST AND LS TTL DATA
4-128
Analog electronics
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