MM74HC164M

The MM74HC164M is a logic-shift register, particularly well-suited for fast data lockup and storage. Its internal design is based on the CMOS logic and contains an 8-bit shift register with the serial input (DS) and serial output (Q7S) connected to an asynchronous Master Reset (MR) terminal. Its wide operating voltage and power supply ranges, plus very low power consumption make the MM74HC164M an ideal device for applications that require low-voltage and low-power operation.

The MM74HC164M is configured by cleverly combining a serial-in “Shift” input, which effectively transfers a data bit from the previous register to the next register at every clock edge, and a parallel-in “Load” input, which loads in all eight bits from the external data source in parallel at the same time. This allows the MM74HC164M device to be used for high-speed serial-to-parallel conversion and parallel-to-serial conversion, as well as quick data transfer and locking up for both digital logic and microprocessor applications.

Analogy using an assembly line provides an easier way to understand how the MM74HC164M works. Suppose eight separate items with different features need to be inspected and sorted in the sequence they were encoded. The first person on the assembly line inspects each feature and either passes the item down the line or rejects it. At the end of the assembly line, the part is accepted or already rejected. The initial stage of the assembly line is always the same - everyone starts with the encoded information. But, after that, it progresses differently for each item.

Using the MM74HC164M shift register device, each part could be inspected separately in the same sequence with each inspection done in a “microsecond”-scale time period. The individual bits representing the parts can be loaded into the MM74HC164M on the parallel data input “Load” (D0 through D7) pins. When the clock is triggered, the first bit is shifted into the serial output “Q7S” pin where it is then evaluated by the next stage. The other bits of the data are clocked looselly into the serial output following the subsequent clock pulses. The parallel input bits, however, remain unchanged until the next clock pulse. Thus, this repeating pattern of a single clock pulse provides the explicit status of the data output at each stage.

In addition, the MM74HC164M also feature a “Master Reset” (MR) input that resets all eight bits to a “zero” logic level when reset is enabled. Thus, the output pins are reset to the same value for all further clock cycles, making sure that the correct data is shifted in each successive register and the device is always in a known state even when the reset input goes from “high” to “low”.

To summarize, the MM74HC164M shift register is a versatile logic device that can be used in a variety of logic and microprocessor applications, allowing for data transmission, storage and manipulation. Its internal design also guarantees consistency in operation over temperature and voltage variations, while its input/output design allows for fast parallel-to-serial and serial-to-parallel conversion.