SN74F543,pdf(Octal Registered

The SN74F543 octal transceiver contains two sets of D-type latches for temporary storage of data flowing in either direction. Separate latch-enable ( or ) and output enable ( or ) inputs are provided for each register to permit independent control in either direction of data flow. The A outputs are characterized to sink 24 mA while the B outputs are characterized to sink 64 mA.

The A-to-B enable () input must be low in order to enter data from A or to output data from B. Having low and low makes the A-to-B latches transparent; a subsequent low-to-high transition of puts the A latches in the storage mode. With and both low, the 3-state B outputs are active and reflect the data present at the output of the A latches.