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4-68
FAST AND LS TTL DATA
MC74F157A
GUARANTEED OPERATING RANGES
Symbol
Parameter
Min
Typ
Max
Unit
VCC
TA
IOH
IOL
Supply Voltage
74
4.5
5.0
5.5
V
Operating Ambient Temperature Range
74
0
25
70
°
C
Output Current — High
74
–1.0
mA
Output Current — Low
74
20
mA
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE
(unless otherwise specified)
Limits
Symbol
Parameter
Min
Typ
Max
Unit
Test Conditions
VIH
VIL
VIK
VOH
Input HIGH Voltage
2.0
V
Guaranteed Input HIGH Voltage
Input LOW Voltage
0.8
V
Guaranteed Input LOW Voltage
Input Clamp Diode Voltage
–1.2
V
IIN = –18 mA
IOH = –1.0 mA
VCC = MIN
VCC = 4.75 V
VCC = 4.50 V
VCC = MIN
VCC = MAX
Output HIGH Voltage
74
2.7
3.4
V
74
2.5
VOL
IIH
Output LOW Voltage
0.35
0.5
V
IOL = 20 mA
VIN = 2.7 V
VIN = 7.0 V
VIN = 0.5 V
VOUT = 0 V
All Inputs = 4.5 V
Input HIGH Current
20
μ
A
μ
A
100
IIL
IOS
ICC
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.
Input LOW Current
–0.6
mA
VCC = MAX
VCC = MAX
VCC = MAX
Output Short Circuit Current (Note 2)
–60
–150
mA
Power Supply Current
15
23
mA
AC CHARACTERISTICS
74F
74F
TA = +25
°
C
VCC = +5.0 V
CL = 50 pF
Min
TA = 0
°
C to 70
°
C
VCC = 5.0 V
±
10%
CL = 50 pF
Min
Symbol
Parameter
Max
Max
Unit
tPLH
tPHL
tPLH
tPHL
tPLH
tPHL
Propagation Delay
3.5
10
3.5
11
ns
S to Zn
Propagation Delay
3.0
7.0
3.0
8.0
3.5
9.5
3.5
11
ns
E to Zn
Propagation Delay
2.5
6.5
2.5
7.0
2.0
6.0
2.0
6.5
ns
In to Zn
2.5
5.5
2.0
7.0
FUNCTIONAL DESCRIPTION
The F157A is a quad 2-input multiplexer. It selects four bits
of data from two sources under the control of a common Select
input (S). The Enable input (E) is active LOW. When E is
HIGH, all of the outputs (Z) are forced LOW regardless of all
other inputs. The F157A is the logic implementation of a
4-pole, 2-position switch where the position of the switch is de-
termined by the logic levels supplied to the Select input. The
logic equations for the outputs are shown below:
Za = E
(I1a
S + I0a
S)
Zc = E
(I1c
S + I0c
S)
A common use of the F157A is the moving of data from two
groups of registers to four common output busses. The partic-
ular register from which the data comes is determined by the
state of the Select input. A less obvious use is as a function
generator. The F157A can generate any four of the 16 different
functions of two variables with one variable common. This is
useful for implementing highly irregular logic.
Zb = E
(I1b
S + I0b
S)
Zd = E
(I1d
S + I0d
S)