The SN74HCS573 contains eight D-type latches. All inputs include Schmitt-trigger architecture. All channels share a latch enable (LE) and output enable (OE) input.

When the latch is enabled (LE is high), data is allowed to pass through from the D inputs to the Q outputs.

When the latch is disabled (LE is low), the Q outputs hold the last state they had regardless of changes at the D inputs.

If the latch enable (LE) input is held low during startup, the output state of all channels is unknown until the latch enable (LE) input is driven high with valid input signals at all data (D) inputs.

When the outputs are enabled (OE is low), the outputs are actively driving low or high.

When the outputs are disabled (OE is high), the outputs are set into the high-impedance state.

The active low output enable (OE) does not have any impact on the stored state in the latches.