Datasheet

SN54LV573A, SN74LV573A
OCTAL TRANSPARENT D-TYPE LATCHES
WITH 3-STATE OUTPUTS
SCLS411I − APRIL 1998 − REVISED APRIL 2005
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
description/ordering information (continued)
The ’LV573A devices are octal transparent D-type latches designed for 2-V to 5.5-V V
CC
operation.
These devices feature 3-state outputs designed specifically for driving highly capacitive or relatively
low-impedance loads. This device is particularly suitable for implementing buffer registers, I/O ports,
bidirectional bus drivers, and working registers.
While the latch-enable (LE) input is high, the Q outputs follow the data (D) inputs. When LE is taken low, the
Q outputs are latched at the logic levels set up at the D inputs.
A buffered output-enable (OE
) input can be used to place the eight outputs in either a normal logic state (high
or low logic levels) or high-impedance state. In the high-impedance state, the outputs neither load nor drive the
bus lines significantly. The high-impedance state and increased drive provide the capability to drive bus lines
without need for interface or pullup components.
OE
does not affect the internal operations of the latches. Old data can be retained or new data can be entered
while the outputs are in the high-impedance state.
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.
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.
terminal assignments
1234
A 1D
OE V
CC
1Q
B 3D 3Q 2D 2Q
C 5D 4D 5Q 4Q
D 7D 7Q 6D 6Q
E GND 8D LE 8Q
FUNCTION TABLE
(each latch)
INPUTS
OUTPUT
OE LE D
OUTPUT
Q
L H H H
L HL L
L LX Q
0
H X X Z
GQN PACKAGE
(TOP VIEW)
1234
A
B
C
D
E