DESCRIPTION

The HEF4508B is a dual 4-bit latch, which consists of two identical independent 4-bit latches with separate strobe (ST), master reset (MR), output-enable input (EO) and 3-state outputs (O).

With the ST input in the HIGH state, the data on the D inputs appear at the corresponding outputs provided EO is LOW. Changing the ST input to the LOW state locks the data into the latch. A HIGH on the reset line forces the outputs to a LOW level regardless of the state of the ST input. The 3-state outputs are controlled by the output-enable input. A HIGH on EO causes the outputs to assume a high impedance OFF-state regardless of other input conditions. This allows the outputs to interface directly with bus orientated systems. When EO is LOW the contents of the latches are available at the outputs.