74ABT543 Fairchild Semiconductor, 74ABT543 Datasheet - Page 2

• Manufacturer Part Number: 74ABT543
• Description: Octal Registered Transceiver with 3-STATE Outputs
• Manufacturer: Fairchild Semiconductor

www.fairchildsemi.com
Functional Description
The ABT543 contains two sets of D-type latches, with sep-
arate input and output controls for each. For data flow from
A to B, for example, the A to B Enable (CEAB) input must
be low in order to enter data from the A Port or take data
from the B Port as indicated in the Data I/O Control Table.
With CEAB low, a low signal on (LEAB) input makes the A
to B latches transparent; a subsequent low to high transi-
tion of the LEAB line puts the A latches in the storage
mode and their outputs no longer change with the A inputs.
With CEAB and OEAB both low, the B output buffers are
active and reflect the data present on the output of the A
latches. Control of data flow from B to A is similar, but using
the CEBA, LEBA and OEBA.
Logic Diagram
2
Data I/O Control Table
H
L
X
CEAB LEAB OEAB
LOW Voltage Level
HIGH Voltage Level
Immaterial
H
X
L
X
L
Inputs
H
X
X
X
L
H
X
X
X
L
Latch Status
Transparent
Latched
Latched
—
—
Output Buffers
HIGH Z
HIGH Z
Driving
—
—