Bidirectional Bus Transceivers in
High-Density 20-Pin Packages
Inverting Logic
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 upon 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 SN74ALS640B is identical to
the standard version, except that the
recommended maximum IOL for the -1 version is
increased to 48 mA. There is no -1 version of the
SN54ALS640B.
The SN54ALS640B and SN54AS640 are
characterized for operation over the full military
temperature range of –55°C to 125°C. The
SN74ALS640B and SN74AS640 are
characterized for operation from 0°C to 70°C.