TL F 6413
54LS245DM54LS245DM74LS245
TRI-STATE
Octal
Bus
Transceiver
June 1989
54LS245 DM54LS245 DM74LS245
TRI-STATE
Octal Bus Transceiver
General Description
These octal bus transceivers are designed for asynchro-
nous two-way communication between data buses The
control function implementation minimizes external timing
requirements
The device allows data transmission from the A bus to the B
bus or from the B bus to the A bus depending upon the logic
level at the direction control (DIR) input The enable input
(G) can be used to disable the device so that the buses are
effectively isolated
Features
Y
Bi-Directional bus transceiver in a high-density 20-pin
package
Y
TRI-STATE outputs drive bus lines directly
Y
PNP inputs reduce DC loading on bus lines
Y
Hysteresis at bus inputs improve noise margins
Y
Typical propagation delay times port-to-port 8 ns
Y
Typical enable disable times 17 ns
Y
I
OL
(sink current)
54LS
12 mA
74LS
24 mA
Y
I
OH
(source current)
54LS
b
12 mA
74LS
b
15 mA
Y
Alternate Military Aerospace device (54LS245) is avail-
able Contact a National Semiconductor Sales Office
Distributor for specifications
Connection Diagram
Dual-In-Line Package
TL F 6413 1
Order Number 54LS245DMQB 54LS245FMQB 54LS245LMQB
DM54LS245J DM54LS245W DM74LS245WM or DM74LS245N
See NS Package Number E20A J20A M20B N20A or W20A
Function Table
Enable
Direction
Operation
G
Control
DIR
L
L
B data to A bus
L
H
A data to B bus
H
X
Isolation
H
e
High Level L
e
Low Level X
e
Irrelevant
TRI-STATE
is a registered trademark of National Semiconductor Corporation
C1995 National Semiconductor Corporation
RRD-B30M105 Printed in U S A
Absolute Maximum Ratings
(Note)
If Military Aerospace specified devices are required
please contact the National Semiconductor Sales
Office Distributors for availability and specifications
Supply Voltage
7V
Input Voltage
DIR or G
7V
A or B
5 5V
Operating Free Air Temperature Range
DM54LS and 54LS
b
55 C to
a
125 C
DM74LS
0 C to
a
70 C
Storage Temperature Range
b
65 C to
a
150 C
Note
The ``Absolute Maximum Ratings'' are those values
beyond which the safety of the device cannot be guaran-
teed The device should not be operated at these limits The
parametric values defined in the ``Electrical Characteristics''
table are not guaranteed at the absolute maximum ratings
The ``Recommended Operating Conditions'' table will define
the conditions for actual device operation
Recommended Operating Conditions
Symbol
Parameter
DM54LS245
DM74LS245
Units
Min
Nom
Max
Min
Nom
Max
V
CC
Supply Voltage
4 5
5
5 5
4 75
5
5 25
V
V
IH
High Level Input Voltage
2
2
V
V
IL
Low Level Input Voltage
0 7
0 8
V
I
OH
High Level Output Current
b
12
b
15
mA
I
OL
Low Level Output Current
12
24
mA
T
A
Free Air Operating Temperature
b
55
125
0
70
C
Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
(Note 1)
V
I
Input Clamp Voltage
V
CC
e
Min I
I
e b
18 mA
b
1 5
V
HYS
Hysteresis (V
Ta
b
V
Tb
)
V
CC
e
Min
0 2
0 4
V
V
OH
High Level Output Voltage
V
CC
e
Min V
IH
e
Min
DM74
2 7
V
IL
e
Max I
OH
e b
1 mA
V
CC
e
Min V
IL
e
Min
DM54 DM74
2 4
3 4
V
V
IL
e
Max I
OH
e b
3 mA
V
CC
e
Min V
IH
e
Min
DM54 DM74
2
V
IL
e
0 5V I
OH
e
Max
V
OL
Low Level Output Voltage
V
CC
e
Min
I
OL
e
12 mA
DM74
0 4
V
IL
e
Max
I
OL
e
Max
DM54
0 4
V
V
IH
e
Min
DM74
0 5
I
OZH
Off-State Output Current
V
CC
e
Max
V
O
e
2 7V
20
m
A
High Level Voltage Applied
V
IL
e
Max
I
OZL
Off-State Output Current
V
IH
e
Min
V
O
e
0 4V
b
200
m
A
Low Level Voltage Applied
I
I
Input Current at Maximum
V
CC
e
Max
A or B
V
I
e
5 5V
0 1
mA
Input Voltage
DIR or G
V
I
e
7V
0 1
I
IH
High Level Input Current
V
CC
e
Max V
I
e
2 7V
20
m
A
I
IL
Low Level Input Current
V
CC
e
Max V
I
e
0 4V
b
0 2
mA
I
OS
Short Circuit Output Current
V
CC
e
Max (Note 2)
b
40
b
225
mA
I
CC
Supply Current
Outputs High
V
CC
e
Max
48
70
Outputs Low
62
90
mA
Outputs at Hi-Z
64
95
Note 1
All typicals are at V
CC
e
5V T
A
e
25 C
Note 2
Not more than one output should be shorted at a time not to exceed one second duration
2
Switching Characteristics
V
CC
e
5V T
A
e
25 C (See Section 1 for Test Waveforms and Output Load)
DM54 74
Symbol
Parameter
Conditions
LS245
Units
Min
Max
t
PLH
Propagation Delay Time Low-to-High-Level Output
12
ns
t
PHL
Propagation Delay Time High-to-Low-Level Output
C
L
e
45 pF
12
ns
t
PZL
Output Enable Time to Low Level
R
L
e
667X
40
ns
t
PZH
Output Enable Time to High Level
40
ns
t
PLZ
Output Disable Time from Low Level
C
L
e
5 pF
25
ns
t
PHZ
Output Disable Time from High Level
R
L
e
667X
25
ns
t
PLH
Propagation Delay Time Low-to-High-Level Output
16
ns
t
PHL
Propagation Delay Time High-to-Low-Level Output
C
L
e
150 pF
17
ns
t
PZL
Output Enable Time to Low Level
R
L
e
667X
45
ns
t
PZH
Output Enable Time to High Level
45
ns
3
Physical Dimensions
inches (millimeters)
Ceramic Leadless Chip Carrier Package (E)
Order Number 54LS245LMQB
NS Package Number E20A
20-Lead Ceramic Dual-In-Line Package (J)
Order Number 54LS245DMQB or DM54LS245J
NS Package Number J20A
4
Physical Dimensions
inches (millimeters) (Continued)
20-Lead Small Outline Molded Package (M)
Order Number DM74LS245WM
NS Package Number M20B
20-Lead Molded Dual-In-Line Package (N)
Order Number DM74LS245N
NS Package Number N20A
5
PDF 
ZIP