These octal D-type edge-triggered flip-flops 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.
On the positive transition of the clock (CLK) input, the Q\ outputs are set to the complement of the logic states set up at the data (D) inputs. The 'ALS534A and SN74AS534 have inverted outputs, but otherwise are functionally equivalent to the 'ALS374A and SN74AS374.
A buffered output-enable () input places 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 interface or pullup components.
does not affect the internal operations of the flip-flops. Old data can be retained or new data can be entered while the outputs are off.
The SN54ALS534A is characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ALS534A and SN74AS534 are characterized for operation from 0°C to 70°C.