CONNECTION DIAGRAMS DIP (TOP VIEW)
18
17
16
15
14
13
1
2
3
4
5
6
7
20
19
8
VCC
DIR
B1
B2
B3
B5
B4
B6
A1
A2
A3
A4
A5
A6
A7
9
10
A8
GND
12
11
B7
B8
18
17
16
15
14
13
1
2
3
4
5
6
7
20
19
8
VCC
DIR
B1
B2
B3
B5
B4
B6
A1
A2
A3
A4
A5
A6
A7
9
10
A8
GND
12
11
B7
B8
SN54 / 74LS640
SN54 / 74LS642
SN54 / 74LS641
SN54 / 74LS645
ENABLE
G
ENABLE
G
5-1
FAST AND LS TTL DATA
OCTAL BUS TRANSCEIVERS
These octal bus transceivers are designed for asynchronous two-way
communication between data buses. Control function implementation
minimizes external timing requirements. These circuits allow data transmis-
sion from the A bus to B or from the B bus to A bus depending upon the logic
level of the direction control (DIR) input. Enable input (G) can disable the
device so that the buses are effectively isolated.
DEVICE
OUTPUT
LOGIC
LS640
3-State
Inverting
LS641
Open-Collector
True
LS642
Open-Collector
Inverting
LS645
3-State
True
FUNCTION TABLE
CONTROL
INPUTS
OPERATION
INPUTS
LS640
LS642
LS641
LS645
G
DIR
LS640
LS642
LS641
LS645
L
L
B data to A bus
B data to A bus
L
H
A data to B bus
A data to B bus
H
X
Isolation
Isolation
H = HIGH Level, L = LOW Level, X = Irrelevant
SN54/74LS640
SN54/74LS641
SN54/74LS642
SN54/74LS645
OCTAL BUS TRANSCEIVERS
LOW POWER SCHOTTKY
ORDERING INFORMATION
SN54LSXXXJ
Ceramic
SN74LSXXXN
Plastic
SN74LSXXXDW SOIC
20
1
J SUFFIX
CERAMIC
CASE 732-03
20
1
N SUFFIX
PLASTIC
CASE 738-03
20
1
DW SUFFIX
SOIC
CASE 751D-03
5-2
FAST AND LS TTL DATA
SN54/74LS640
SN54/74LS645
GUARANTEED OPERATING RANGES
Symbol
Parameter
Min
Typ
Max
Unit
VCC
Supply Voltage
54
74
4.5
4.75
5.0
5.0
5.5
5.25
V
TA
Operating Ambient Temperature Range
54
74
55
0
25
25
125
70
C
IOH
Output Current -- High
54, 74
3.0
mA
OH
54
74
12
15
mA
IOL
Output Current -- Low
54
74
12
24
mA
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE
(unless otherwise specified)
Symbol
Parameter
Limits
Unit
Test Conditions
Symbol
Parameter
Min
Typ
Max
Unit
Test Conditions
VIH
Input HIGH Voltage
2.0
V
Guaranteed Input HIGH Voltage for
All Inputs
VIL
Input LOW Voltage
54
0.5
V
Guaranteed Input LOW Voltage for
VIL
Input LOW Voltage
74
0.6
V
Guaranteed Input LOW Voltage for
All Inputs
VIK
Input Clamp Diode Voltage
0.65
1.5
V
VCC = MIN, IIN = 18 mA
VOH
Output HIGH Voltage
54, 74
2.4
3.4
V
VCC = MIN, IOH = 3.0 mA
VOH
Output HIGH Voltage
54, 74
2.0
V
VCC = MIN, IOH = MAX
VOL
Output LOW Voltage
54, 74
0.25
0.4
V
IOL = 12 mA
VCC = VCC MIN,
VIN = VIL or VIH
per Truth Table
VOL
Output LOW Voltage
74
0.35
0.5
V
IOL = 24 mA
VIN = VIL or VIH
per Truth Table
IOZH
Output Off Current HIGH
20
A
VCC = MAX, VOUT = 2.7 V
IOZL
Output Off Current LOW
400
A
VCC = MAX, VOUT = 0.4 V
IIH
Input HIGH Current
A or B, DIR or G
20
A
VCC = MAX, VIN = 2.7 V
IIH
Input HIGH Current
DIR or G
0.1
mA
VCC = MAX, VIN = 7.0 V
IH
A or B
0.1
mA
VCC = MAX, VIN = 5.5 V
IIL
Input LOW Current
0.4
mA
VCC = MAX, VIN = 0.4 V
IOS
Output Short Circuit Current (Note 1)
40
225
mA
VCC = MAX
ICC
Power Supply Current
Total Output HIGH
70
mA
VCC = MAX
ICC
Total, Output LOW
90
mA
VCC = MAX
Total at HIGH Z
95
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
AC CHARACTERISTICS
(TA = 25
C, VCC = 5.0 V)
Symbol
Parameter
Limits
Unit
Test Conditions
Symbol
Parameter
LS640
LS645
Unit
Test Conditions
Symbol
Parameter
Min
Typ
Max
Min
Typ
Max
Unit
Test Conditions
tPLH
tPHL
Propagation Delay
A to B
6.0
8.0
10
15
8.0
11
15
15
ns
CL = 45 pF,
RL = 667
tPLH
tPHL
Propagation Delay
B to A
6.0
8.0
10
15
8.0
11
15
15
ns
CL = 45 pF,
RL = 667
tPZL
tPZH
Output Enable Time
G, DIR to A
31
23
40
40
31
26
40
40
ns
CL = 45 pF,
RL = 667
tPZL
tPZH
Output Enable Time
G, DIR to B
31
23
40
40
31
26
40
40
ns
tPLZ
tPHZ
Output Disable Time
G, DIR to A
15
15
25
25
15
15
25
25
ns
CL = 5.0 pF
tPLZ
tPHZ
Output Disable Time
G, DIR to B
15
15
25
25
15
15
25
25
ns
CL = 5.0 pF
5-3
FAST AND LS TTL DATA
SN54/74LS641
SN54/74LS642
GUARANTEED OPERATING RANGES
Symbol
Parameter
Min
Typ
Max
Unit
VCC
Supply Voltage
54
74
4.5
4.75
5.0
5.0
5.5
5.25
V
TA
Operating Ambient Temperature Range
54
74
55
0
25
25
125
70
C
VOH
Output Current -- High
54, 74
5.5
V
IOL
Output Current -- Low
54
74
12
24
mA
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE
(unless otherwise specified)
Symbol
Parameter
Limits
Unit
Test Conditions
Symbol
Parameter
Min
Typ
Max
Unit
Test Conditions
VIH
Input HIGH Voltage
2.0
V
Guaranteed Input HIGH Voltage for
All Inputs
VIL
Input LOW Voltage
54
0.5
V
Guaranteed Input LOW Voltage for
All Inputs
VIL
Input LOW Voltage
74
0.6
V
Guaranteed Input LOW Voltage for
All Inputs
VIK
Input Clamp Diode Voltage
0.65
1.5
V
VCC = MIN, IIN = 18 mA
IOH
Output HIGH Current
54, 74
100
A
VCC = MIN, VOH = MAX
VOL
Output LOW Voltage
54, 74
0.25
0.4
V
IOL = 12 mA
VCC = VCC MIN,
VIN = VIL or VIH
per Truth Table
VOL
Output LOW Voltage
74
0.35
0.5
V
IOL = 24 mA
VIN = VIL or VIH
per Truth Table
IIH
Input HIGH Current
20
A
VCC = MAX, VIN = 2.7 V
IIH
Input HIGH Current
0.1
mA
VCC = MAX, VIN = 7.0 V
IIL
Input LOW Current
0.4
mA
VCC = MAX, VIN = 0.4 V
ICC
Power Supply Current
Total, Output HIGH
70
mA
VCC = MAX
ICC
Total, Output LOW
90
mA
VCC = MAX
Total at HIGH Z
95
AC CHARACTERISTICS
(TA = 25
C, VCC = 5.0 V)
Symbol
Parameter
Limits
Unit
Test Conditions
Symbol
Parameter
LS641
LS642
Unit
Test Conditions
Symbol
Parameter
Min
Typ
Max
Min
Typ
Max
Unit
Test Conditions
tPLH
tPHL
Propagation Delay,
A to B
17
16
25
25
19
14
25
25
ns
CL = 45 pF,
RL = 667
tPLH
tPHL
Propagation Delay,
B to A
17
16
25
25
19
14
25
25
ns
CL = 45 pF,
RL = 667
tPLH
tPHL
Propagation Delay,
G, DIR to A
23
34
40
50
26
43
40
60
ns
CL = 45 pF,
RL = 667
tPLH
tPHL
Propagation Delay,
G, DIR to B
25
37
40
50
28
39
40
60
ns
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