SN54ALS645A, SN54AS645, SN74ALS645A, SN74AS645
OCTAL BUS TRANSCEIVERS
WITH 3-STATE OUTPUTS
SDAS278 – JANUARY 1995
Copyright  1995, Texas Instruments Incorporated
1POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
• Bidirectional Bus Transceivers in
High-Density 20-Pin Packages
• True Logic
• 3-State Outputs
• Package Options Include Plastic
Small-Outline (DW) Packages, Ceramic
Chip Carriers (FK), and Standard Plastic (N)
and Ceramic (J) 300-mil DIPs

description
These octal bus transceivers are designed for
asynchronous two-way communication between
data buses. These devices transmit data from the
A bus to the B bus or from the B bus to the A bus,
depending on the level at the direction-control
(DIR) input. The output-enable (OE) input can be
used to disable the device so that the buses are
effectively isolated.
The -1 version of the SN74ALS645A is identical
to the standard version, except that the
recommended maximum I
OL
is increased to
48 mA. There is no -1 version of the
SN54ALS645A.
The SN54ALS645A and SN54AS645 are
characterized for operation over the full military
temperature range of –55°C to 125°C. The
SN74ALS645A and SN74AS645 are
characterized for operation from 0°C to 70°C.
FUNCTION TABLE
INPUTS
OPERATION
OE DIR
L L B data to A bus
L H A data to B bus
H X Isolation
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
DIR
A1
A2
A3
A4
A5
A6
A7
A8
GND
V
CC
OE
B1
B2
B3
B4
B5
B6
B7
B8
SN54ALS645A, SN54AS645 ...J PACKAGE
SN74ALS645A, SN74AS645 . . . DW OR N PACKAGE
(TOP VIEW)
3212019
910 11 12 13
4
5
6
7
8
18
17
16
15
14
B1
B2
B3
B4
B5
A3
A4
A5
A6
A7
SN54ALS645A, SN54AS645 . . . FK PACKAGE
(TOP VIEW)
A2 A1 DIR
B7 B6
OE
A8
GND
B8
V
CC
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.