Datasheet

DESCRIPTION/ORDERING INFORMATION (CONTINUED)
B
DIR
5
4
A
3
V
CCA
V
CCB
SN74LVC1T45-EP
SCES768 – NOVEMBER 2008 ........................................................................................................................................................................................... www.ti.com
The SN74LVC1T45 is designed for asynchronous communication between two data buses. The logic levels of
the direction-control (DIR) input activate either the B-port outputs or the A-port outputs. The device transmits data
from the A bus to the B bus when the B-port outputs are activated and from the B bus to the A bus when the
A-port outputs are activated. The input circuitry on both A and B ports always is active and must have a logic
HIGH or LOW level applied to prevent excess I
CC
and I
CCZ
.
The SN74LVC1T45 is designed so that the DIR input is powered by V
CCA
.
This device is fully specified for partial-power-down applications using I
off
. The I
off
circuitry disables the outputs,
preventing damaging current backflow through the device when it is powered down.
The V
CC
isolation feature ensures that if either V
CC
input is at GND, then both ports are in the high-impedance
state.
FUNCTION TABLE
(1)
INPUT
OPERATION
DIR
L B data to A bus
H A data to B bus
(1) Input circuits of the data I/Os
always are active.
LOGIC DIAGRAM (POSITIVE LOGIC)
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