SCAS538G October 1995 – March 2024 SN54ACT573 , SN74ACT573
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
The eight latches are D-type transparent latches. When 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 the 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 in a bus-organized system 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 put the device in the high-impedance state during power up or power down, tie OE to VCC through a pullup resistor; the current-sinking capability of the driver determines the minimum value of the resistor.