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2

Logic Symbols

IEEE/IEC

Functional Description

The LVTH543 contains two sets of D-type latches, with

separate 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 transition 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 out-

put 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.

Data I/O Control Table

H

= HIGH Voltage Level

L

= LOW Voltage Level

X

= Immaterial

Note: A-to-B data flow shown; B-to-A flow control is the same, except

using CEBA, LEBA, and OEBA.

Logic Diagram

Please not that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.

Inputs

Latch Status

Output

CEAB

LEAB

OEAB

Buffers

H

X

X

Latched

High Z

X

H

X

Latched

—

L

L

X

Transparent

—

XX

H

—

High Z

L

X

L

—

Driving