54LS245 DM54LS245 DM74LS245 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
Y
Y
Y
Y
Y
Y
Features
Y
Y
Y
Bi-Directional bus transceiver in a high-density 20-pin
package
TRI-STATE outputs drive bus lines directly
PNP inputs reduce DC loading on bus lines
Hysteresis at bus inputs improve noise margins
Typical propagation delay times port-to-port 8 ns
Typical enable disable times 17 ns
I
OL
(sink current)
54LS
12 mA
74LS
24 mA
I
OH
(source current)
b
12 mA
54LS
b
15 mA
74LS
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
G
L
L
H
Direction
Control
DIR
L
H
X
Operation
B data to A bus
A data to B bus
Isolation
H
e
High Level L
e
Low Level X
e
Irrelevant
TRI-STATE is a registered trademark of National Semiconductor Corporation
C
1995 National Semiconductor Corporation
TL F 6413
RRD-B30M105 Printed in U S A
NSC [ NATIONAL SEMICONDUCTOR ]
