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
LS641
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
p
g
54
74
12
15
mA
IOL
Output Current -- Low
54
74
12
24
mA
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE
(unless otherwise specified)
S
b l
P
Limits
U i
T
C
di i
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
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
I
I
HIGH C
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
p
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
I
Power Supply Current
Total Output HIGH
70
mA
V
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)
S
b l
P
Limits
U i
T
C
di i
S
b l
P
LS640
LS645
U i
T
C
di i
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
C
45 F
tPLH
tPHL
Propagation Delay
B to A
6.0
8.0
10
15
8.0
11
15
15
ns
CL = 45 pF,
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)
S
b l
P
Limits
U i
T
C
di i
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
p
g
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
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
I
Power Supply Current
Total, Output HIGH
70
mA
V
MAX
ICC
Total, Output LOW
90
mA
VCC = MAX
Total at HIGH Z
95
AC CHARACTERISTICS
(TA = 25
C, VCC = 5.0 V)
S
b l
P
Limits
U i
T
C
di i
S
b l
P
LS641
LS642
U i
T
C
di i
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
C
45 F
tPLH
tPHL
Propagation Delay,
B to A
17
16
25
25
19
14
25
25
ns
CL = 45 pF,
tPLH
tPHL
Propagation Delay,
G, DIR to A
23
34
40
50
26
43
40
60
ns
L
p ,
RL = 667
tPLH
tPHL
Propagation Delay,
G, DIR to B
25
37
40
50
28
39
40
60
ns
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