TECHNICAL DATA
IN74ACT257
Quad 2-Input Data Selector/Multiplexer
with 3-State Outputs
High-Speed Silicon-Gate CMOS
The IN74ACT257 is identical in pinout to the LS/ALS257,
HC/HCT257. The IN74ACT257 may be used as a level converter for
interfacing TTL or NMOS outputs to High Speed CMOS inputs.
This device selects a (4-bit) nibble from either the A or B inputs as
determined by the Select input. The nibble is presented at the outputs in
noninverted from when the Output Enable pin is at a low level. A high
level on the Output Enable pin switches the outputs into the high-
impedance state.
•
TTL/NMOS Compatible Input Levels
•
Outputs Directly Interface to CMOS, NMOS, and TTL
•
Operating Voltage Range: 4.5 to 5.5 V
•
Low Input Current: 1.0
µA;
0.1
µA
@ 25°C
•
Outputs Source/Sink 24 mA
ORDERING INFORMATION
IN74ACT257N Plastic
IN74ACT257D SOIC
T
A
= -40° to 85° C for all packages
PIN ASSIGNMENT
LOGIC DIAGRAM
FUNCTION TABLE
Inputs
Output
Enable
H
L
L
PIN 16 =V
CC
PIN 8 = GND
Select
X
L
H
Outputs
Y0-Y3
Z
A0-A3
B0-B3
X=don’t care
Z = high-impedance state
A0-A3,B0-B3=the levels of the respective
Nibble Inputs
Rev. 00
IN74ACT257
MAXIMUM RATINGS
*
Symbol
V
CC
V
IN
V
OUT
I
IN
I
OUT
I
CC
P
D
Tstg
T
L
*
Parameter
DC Supply Voltage (Referenced to GND)
DC Input Voltage (Referenced to GND)
DC Output Voltage (Referenced to GND)
DC Input Current, per Pin
DC Output Sink/Source Current, per Pin
DC Supply Current, V
CC
and GND Pins
Power Dissipation in Still Air, Plastic DIP+
SOIC Package+
Storage Temperature
Lead Temperature, 1 mm from Case for 10 Seconds
(Plastic DIP or SOIC Package)
Value
-0.5 to +7.0
-0.5 to V
CC
+0.5
-0.5 to V
CC
+0.5
±20
±50
±50
750
500
-65 to +150
260
Unit
V
V
V
mA
mA
mA
mW
°C
°C
Maximum Ratings are those values beyond which damage to the device may occur.
Functional operation should be restricted to the Recommended Operating Conditions.
+Derating - Plastic DIP: - 10 mW/°C from 65° to 125°C
SOIC Package: : - 7 mW/°C from 65° to 125°C
RECOMMENDED OPERATING CONDITIONS
Symbol
V
CC
V
IN
, V
OUT
T
J
T
A
I
OH
I
OL
t
r
, t
f
*
Parameter
DC Supply Voltage (Referenced to GND)
DC Input Voltage, Output Voltage (Referenced to GND)
Junction Temperature (PDIP)
Operating Temperature, All Package Types
Output Current - High
Output Current - Low
Input Rise and Fall Time
*
(except Schmitt Inputs)
V
CC
=4.5 V
V
CC
=5.5 V
Min
4.5
0
-40
Max
5.5
V
CC
140
+85
-24
24
Unit
V
V
°C
°C
mA
mA
ns/V
0
0
10
8.0
V
IN
from 0.8 V to 2.0 V
This device contains protection circuitry to guard against damage due to high static voltages or electric fields.
However, precautions must be taken to avoid applications of any voltage higher than maximum rated voltages to this
high-impedance circuit. For proper operation, V
IN
and V
OUT
should be constrained to the range GND≤(V
IN
or
V
OUT
)≤V
CC
.
Unused inputs must always be tied to an appropriate logic voltage level (e.g., either GND or V
CC
). Unused
outputs must be left open.
Rev. 00
IN74ACT257
DC ELECTRICAL CHARACTERISTICS
(Voltages Referenced to GND)
V
CC
Symbol
V
IH
V
IL
V
OH
Parameter
Minimum High-
Level Input Voltage
Maximum Low -
Level Input Voltage
Minimum High-
Level Output Voltage
Test Conditions
V
OUT
=0.1 V or V
CC
-0.1 V
V
OUT
=0.1 V or V
CC
-0.1 V
I
OUT
≤
-50
µA
V
IN
=V
IH
or V
IL
I
OH
=-24 mA
I
OH
=-24 mA
V
OL
Maximum Low-
Level Output Voltage
I
OUT
≤
50
µA
*
*
Guaranteed Limits
25
°C
2.0
2.0
0.8
0.8
4.4
5.4
3.86
4.86
0.1
0.1
0.36
0.36
±0.1
-40°C to
85°C
2.0
2.0
0.8
0.8
4.4
5.4
3.76
4.76
0.1
0.1
0.44
0.44
±1.0
1.5
±0.5
±5.0
µA
mA
µA
V
Unit
V
V
V
V
4.5
5.5
4.5
5.5
4.5
5.5
4.5
5.5
4.5
5.5
4.5
5.5
5.5
5.5
5.5
V
IN
=V
IH
or V
IL
I
OL
=24 mA
I
OL
=24 mA
V
IN
=V
CC
or GND
V
IN
=V
CC
- 2.1 V
I
IN
∆I
CCT
I
OZ
Maximum Input
Leakage Current
Additional Max.
I
CC
/Input
Maximum Three-
State Leakage
Current
+Minimum Dynamic
Output Current
+Minimum Dynamic
Output Current
Maximum Quiescent
Supply Current
(per Package)
V
IN
(OE)= V
IH
or V
IL
V
IN
=V
CC
or GND
V
OUT
=V
CC
or GND
V
OLD
=1.65 V Max
V
OHD
=3.85 V Min
V
IN
=V
CC
or GND
I
OLD
I
OHD
I
CC
5.5
5.5
5.5
8.0
75
-75
80
mA
mA
µA
*
All outputs loaded; thresholds on input associated with output under test.
+Maximum test duration 2.0 ms, one output loaded at a time.
Rev. 00
IN74ACT257
AC ELECTRICAL CHARACTERISTICS
(V
CC
=5.0 V
±
10%, C
L
=50pF, Input t
r
=t
f
=3.0 ns)
Guaranteed Limits
Symbol
t
PLH
t
PHL
t
PLH
t
PHL
t
PZH
t
PZL
t
PHZ
t
PLZ
C
IN
Parameter
Propagation Delay, Nibble A or B to Output Y
(Figure 1)
Propagation Delay, Nibble A or B to Output Y
(Figure 1)
Propagation Delay, Select to Output Y
(Figure 2)
Propagation Delay, Select to Output Y
(Figure 2)
Propagation Delay, Output Enable to Output Y
(Figure 3)
Propagation Delay, Output Enable to Output Y
(Figure 3)
Propagation Delay, Output Enable to Output Y
(Figure 3)
Propagation Delay, Output Enable to Output Y
(Figure 3)
Maximum Input Capacitance
25
°C
Min
1.5
2.0
2.0
2.5
2.0
2.0
2.5
2.0
4.5
Max
7.0
7.5
9.5
10.5
8.0
8.0
9.0
7.5
-40°C to 85°C
Min
1.0
1.5
1.5
2.0
1.5
1.5
1.5
1.5
4.5
Max
7.5
8.5
10.5
11.5
9.0
9.0
10.0
8.5
ns
ns
ns
ns
ns
ns
ns
ns
pF
Unit
Typical @25°C,V
CC
=5.0 V
C
PD
Power Dissipation Capacitance
50
pF
Figure 1. Switching Waveforms
Figure 2. Switching Waveforms
Rev. 00
IN74ACT257
Figure 3. Switching Waveforms
EXPANDED LOGIC DIAGRAM
Rev. 00
模拟电子
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