These 8-bit latches feature 3-state outputs designed specifically
for driving highly capacitive or relatively low-impedance loads. They
are particularly suitable for implementing buffer registers, I/O
ports, bidirectional bus drivers, and working registers.
The eight latches of the ´F573 are transparent D-type
latches. While the latch enable (LE) input is high, the Q outputs
follow the data (D) inputs. When the latch enable is taken low, the Q
outputs are latched at the logic levels set up at the D inputs.
A buffered output enable
input can be used to place the eight outputs in either a normal logic
state (high or low logic levels) or a 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.
The output enable
input 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.
The SN54F573 is characterized for operation over the full military
temperature range of -55°C to 125°C. The SN74F573 is
characterized for operation from 0°C to 70°C.