SN74LS240 SN74LS244
Octal Buffer/Line Driver
with 3-State Outputs
The SN74LS240 and SN74LS244 are Octal Buffers and Line
Drivers designed to be employed as memory address drivers, clock
drivers and bus-oriented transmitters/receivers which provide
improved PC board density.
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•
Hysteresis at Inputs to Improve Noise Margins
•
3-State Outputs Drive Bus Lines or Buffer Memory Address
Registers
•
Input Clamp Diodes Limit High-Speed Termination Effects
GUARANTEED OPERATING RANGES
Symbol
V
CC
T
A
I
OH
Parameter
Supply Voltage
Operating Ambient
Temperature Range
Output Current – High
Min
4.75
0
Typ
5.0
25
Max
5.25
70
– 3.0
– 15
I
OL
Output Current – Low
24
Unit
V
°C
20
LOW
POWER
SCHOTTKY
mA
mA
mA
1
PLASTIC
N SUFFIX
CASE 738
20
1
SOIC
DW SUFFIX
CASE 751D
ORDERING INFORMATION
Device
SN74LS240N
SN74LS240DW
SN74LS244N
SN74LS244DW
Package
16 Pin DIP
16 Pin
16 Pin DIP
16 Pin
Shipping
1440 Units/Box
2500/Tape & Reel
1440 Units/Box
2500/Tape & Reel
©
Semiconductor Components Industries, LLC, 1999
1
December, 1999 – Rev. 6
Publication Order Number:
SN74LS240/D
SN74LS240 SN74LS244
LOGIC AND CONNECTION DIAGRAMS DIP
(TOP VIEW)
SN74LS240
V
CC
20
2G
19
1Y1
18
2A4 1Y2 2A3 1Y3 2A2 1Y4 2A1
17
16
15
14
13
12
11
1
1G
2
1A1
3
4
5
2Y4 1A2 2Y3
6
8
9
10
7
1A3 2Y2 1A4 2Y1 GND
SN74LS244
V
CC
20
2G
19
1Y1
18
2A4 1Y2 2A3 1Y3 2A2 1Y4 2A1
17
16
15
14
13
12
11
1
1G
2
1A1
3
4
5
2Y4 1A2 2Y3
6
8
9
10
7
1A3 2Y2 1A4 2Y1 GND
TRUTH TABLES
SN74LS240
INPUTS
OUTPUT
1G, 2G
L
L
H
D
L
H
X
H
L
(Z)
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
Z = HIGH Impedance
SN74LS244
INPUTS
OUTPUT
1G, 2G
L
L
H
D
L
H
X
L
H
(Z)
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2
SN74LS240 SN74LS244
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE
(unless otherwise specified)
Limits
Symbol
V
IH
V
IL
V
T+
–V
T–
V
IK
V
O
OH
Parameter
Input HIGH Voltage
Input LOW Voltage
Hysteresis
Input Clamp Diode Voltage
2.4
Output HIGH Voltage
2.0
0.25
V
O
OL
I
OZH
I
OZL
I
IH
I
IL
I
OS
Output LOW Voltage
0.35
Output Off Current HIGH
Output Off Current LOW
Input HIGH Current
0.1
Input LOW Current
Output Short Circuit Current (Note 1)
Power Supply Current
Total, Output HIGH
Total, Output LOW
I
CC
Total at HIGH Z
LS240
LS244
LS240
LS244
– 40
– 0.2
– 225
27
44
46
50
54
mA
A
V
CC
= MAX
0.5
20
– 20
20
V
µA
µA
µA
mA
mA
mA
I
OL
= 24 mA
0.4
V
V
0.2
0.4
– 0.65
3.4
– 1.5
Min
2.0
0.8
Typ
Max
Unit
V
V
V
V
V
Test Conditions
Guaranteed Input HIGH Voltage for
All Inputs
Guaranteed Input LOW Voltage for
All Inputs
V
CC
= MIN
V
CC
= MIN, I
IN
= – 18 mA
V
CC
= MIN, I
OH
= – 3.0 mA
V
CC
= MIN, I
OH
= MAX
I
OL
= 12 mA
V
CC
= V
CC
MIN,
V
IN
= V
IL
or V
IH
per Truth Table
V
CC
= MAX, V
OUT
= 2.7 V
V
CC
= MAX, V
OUT
= 0.4 V
V
CC
= MAX, V
IN
= 2.7 V
V
CC
= MAX, V
IN
= 7.0 V
V
CC
= MAX, V
IN
= 0.4 V
V
CC
= MAX
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
AC CHARACTERISTICS
(T
A
= 25°C, V
CC
= 5.0 V)
Limits
Symbol
t
PLH
t
PHL
t
PLH
t
PHL
t
PZH
t
PZL
t
PLZ
t
PHZ
Parameter
Propagation Delay, Data to Output
LS240
Propagation Delay, Data to Output
LS244
Output Enable Time to HIGH Level
Output Enable Time to LOW Level
Output Disable Time from LOW Level
Output Disable Time from HIGH Level
Min
Typ
9.0
12
12
12
15
20
15
10
Max
14
18
18
18
23
30
25
18
Unit
ns
ns
ns
ns
ns
ns
C
L
= 5.0 pF,
R
L
= 667
Ω
C
L
= 45 pF,
R
L
= 667
Ω
Test Conditions
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3
SN74LS240 SN74LS244
AC WAVEFORMS
V
IN
1.3 V
t
PLH
1.3 V
t
PHL
1.3 V
V
CC
R
L
V
OUT
1.3 V
Figure 1.
SW1
TO OUTPUT
UNDER TEST
V
IN
1.3 V
t
PHL
V
OUT
1.3 V
1.3 V
t
PLH
1.3 V
C
L
*
5 kΩ
SW2
Figure 2.
V
E
V
E
V
OUT
1.3 V
t
PZL
1.3 V
1.3 V
t
PLZ
≈
1.3 V
V
OL
0.5 V
SWITCH POSITIONS
SYMBOL
t
PZH
t
PZL
t
PLZ
t
PHZ
SW1
Open
Closed
Closed
Closed
SW2
Closed
Open
Closed
Closed
Figure 3.
Figure 5.
V
E
1.3 V
V
E
V
OUT
t
PZH
1.3 V
1.3 V
t
PHZ
≥V
OH
≈
1.3 V
0.5 V
Figure 4.
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4
SN74LS240 SN74LS244
PACKAGE DIMENSIONS
N SUFFIX
PLASTIC PACKAGE
CASE 738–03
ISSUE E
–A–
20
11
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION L TO CENTER OF LEAD WHEN
FORMED PARALLEL.
4. DIMENSION B DOES NOT INCLUDE MOLD
FLASH.
INCHES
MIN
MAX
1.010
1.070
0.240
0.260
0.150
0.180
0.015
0.022
0.050 BSC
0.050
0.070
0.100 BSC
0.008
0.015
0.110
0.140
0.300 BSC
0
_
15
_
0.020
0.040
MILLIMETERS
MIN
MAX
25.66
27.17
6.10
6.60
3.81
4.57
0.39
0.55
1.27 BSC
1.27
1.77
2.54 BSC
0.21
0.38
2.80
3.55
7.62 BSC
0
_
15
_
0.51
1.01
B
1
10
C
L
–T–
SEATING
PLANE
K
M
E
G
F
D
20 PL
N
J
0.25 (0.010)
M
20 PL
0.25 (0.010)
T A
M
M
T B
M
DIM
A
B
C
D
E
F
G
J
K
L
M
N
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5
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