8 Bit Parallel to Serial Converter DM74165
General Description 8-Bit Parallel-to-Serial Converter DM74165
The ‘165 is an 8-bit parallel load or serial-in register with complementary outputs available from the last stage. Parallel inputting occurs asynchronously when the Parallel Load (PL) input is LOW. With PL HIGH, serial shifting occurs on the rising edge of the clock; new data enters via the Serial Data (DS) input. The 2-input OR clock can be used to combine two independent clock sources, or one input can act as an active LOW clock enable.
Functional Description Of 8-Bit Parallel-to-Serial Converter DM74165
The ‘165 contains eight clocked master/slave RS flip-flops connected as a shift register with auxiliary gating to provide overriding asynchronous parallel entry. Parallel data enters when the PL signal is LOW. The parallel data can change while PL is LOW provided that the recommended setup and hold times are observed. For clocked operation, PL must be HIGH. The two clock inputs perform identically; one can be used as a clock inhibit by applying a HIGH signal. To avoid double clocking, however, the inhibit signal should only go HIGH while the clock is HIGH. Otherwise, the rising inhibit signal will cause the same response as a rising clock edge. The flip-flops are edge-triggered for serial operations. The serial input data can change at any time, provided only that the recommended setup and hold times are observed, with respect to the rising edge of the clock.