74HC166D

The 74HC166; 74HCT166 is an 8-bit serial or parallel-in/serial-out shift register. The device features a serial data input (DS), eight parallel data inputs (D0 to D7) and a serial output (Q7). When the parallel enable input (PE) is LOW, the data from D0 to D7 is loaded into the shift register on the next LOW‑to‑HIGH transition of the clock input (CP). When PE is HIGH, data enters the register serially at DS with each LOW‑to‑HIGH transition of CP. When the clock enable input (CE) is LOW data is shifted on the LOW‑to‑HIGH transitions of CP. A HIGH on CE disables the CP input. Inputs include clamp diodes which enable the use of current limiting resistors to interface inputs to voltages in excess of V_CC.