SN74ALS620A, SN74ALS621A, SN74ALS623A, SN74AS623
OCTAL BUS TRANSCEIVERS
SDAS226A – DECEMBER 1982 – REVISED JANUARY 1995
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•
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Local Bus-Latch Capability
Choice of True or Inverting Logic
Package Options Include Plastic
Small-Outline (DW) Packages and Standard
Plastic (N) 300-mil DIPs
DEVICE
SN74ALS620A
SN74ALS621A
SN74ALS623A, SN74AS623
OUTPUT
3 state
Open collector
3 state
LOGIC
Inverting
True
True
DW OR N PACKAGE
(TOP VIEW)
description
OEAB
A1
A2
A3
A4
A5
A6
A7
A8
GND
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
V
CC
OEBA
B1
B2
B3
B4
B5
B6
B7
B8
These octal bus transceivers are designed for asynchronous two-way communication between data buses. The
control-function implementation allows for maximum flexibility in timing.
These devices allow data transmission from the A bus to the B bus or from the B bus to the A bus, depending
upon the logic levels at the output-enable (OEAB and OEBA) inputs.
The output-enable inputs disable the device so that the buses are effectively isolated. The dual-enable
configuration gives the transceivers the capability to store data by simultaneously enabling OEAB and OEBA.
Each output reinforces its input in this transceiver configuration. When both OEAB and OEBA are enabled and
all other data sources to the two sets of bus lines are in the high-impedance state, both sets of bus lines (16 total)
remain at their last states. The 8-bit codes appearing on the two sets of buses are identical for the
SN74ALS621A, SN74ALS623A, and SN74AS623 or complementary for the SN74ALS620A.
The -1 versions of the SN74ALS620A and SN74ALS621A are identical to the standard versions, except that
the recommended maximum I
OL
is increased to 48 mA in the -1 versions.
The SN74ALS620A, SN74ALS621A, SN74ALS623A, and SN74AS623 are characterized for operation from
0°C to 70°C.
FUNCTION TABLE
INPUTS
OEBA
L
H
H
L
OEAB
L
H
L
H
OPERATION
SN74ALS620A
B data to A bus
A data to B bus
Isolation
B data to A bus,
A data to B bus
SN74ALS621A
SN74ALS623A
SN74AS623
B data to A bus
A data to B bus
Isolation
B data to A bus,
A data to B bus
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.
Copyright
©
1995, Texas Instruments Incorporated
POST OFFICE BOX 655303
•
DALLAS, TEXAS 75265
1
TI [ TEXAS INSTRUMENTS ]
