DESCRIPTION
The HC164 is an 8 bit shift register with serial data entry and an output from each of the eight stages. Data is entered serially through one of two inputs (A or B), either of these inputs can be used as an active high enable for data entry through the other input. An unused input must be high, or both inputs connected together. Each low-to-high transition on the clock input shifts data one place to the right and enters into QA, the logic NAND of the two data inputs (A ⋅ B), the data that existed before the rising clock edge. A low level on the clear input overrides all other inputs and clears the register asynchronously, forcing all Q outputs low. All inputs are equipped with protection circuits against static discharge and transient excess voltage. October 1992 NC = No Internal Connection 1/12 M54/M74HC164 INPUT AND OUTPUT EQUIVALENT CIRCUIT TRUTH TABLE INPUTS CLEAR L H H H H CLOCK X SERIAL IN A X X L X H B X X X L H L L H QA L QB L QAn QAn QAn OUTPUS ............ ............
STMicroelectronics
