Datasheet

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DESCRIPTION/ORDERING INFORMATION (CONTINUED)
OE1
OE2
To Seven Other Channels
A1
Y1
1
19
2 18
SN54LVC540A, SN74LVC540A
OCTAL BUFFERS/DRIVERS
WITH 3-STATE OUTPUTS
SCAS297M – JANUARY 1993 – REVISED MAY 2005
The 3-state control gate is a 2-input AND gate with active-low inputs so that, if either output-enable ( OE1 or OE2)
input is high, all outputs are in the high-impedance state.
Inputs can be driven from either 3.3-V or 5-V devices. This feature allows the use of these devices as translators
in a mixed 3.3-V/5-V system environment.
These devices are fully specified for partial-power-down applications using I
off
. The I
off
circuitry disables the
outputs, preventing damaging current backflow through the devices when they are powered down.
To ensure the high-impedance state during power up or power down, OE should be tied to V
CC
through a pullup
resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.
FUNCTION TABLE
INPUTS
OUTPUT
Y
OE1 OE2 A
L L L H
L L H L
H X X Z
X H X Z
LOGIC DIAGRAM (POSITIVE LOGIC)
2