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