Two-Way Asynchronous Communication
Between Data Buses
pnp Inputs Reduce dc Loading
Package Options Include Plastic
Small-Outline (D) Packages, Ceramic Chip
Carriers (FK), and Standard Plastic (N) and
Ceramic (J) 300-mil DIPs

description
These quadruple 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 (OEBA and OEAB) inputs. The
output-enable inputs can be used to disable the
device so that the buses are effectively isolated.
The dual-enable configuration gives the
quadruple bus transceivers the capability to store
data by simultaneously enabling OEBA and
OEAB. Each output reinforces its input in this
transceiver configuration. When both control
inputs are enabled and all other data sources to
the two sets of bus lines are at high impedance,
both sets of bus lines (eight in all) retain their
states. The 4-bit codes appearing on the two sets
of buses are identical.
The SN54ALS243A is characterized for operation over the full military temperature range of −55°C to 125°C.
The SN74ALS243A is characterized for operation from 0°C to 70°C.