onsemi MC74HC165ADR2G: 8-Bit Parallel-Load Shift Register Datasheet and Application Overview

The MC74HC165ADR2G from onsemi is a high-performance, 8-bit parallel-load shift register belonging to the 74HC high-speed CMOS logic family. This integrated circuit is engineered to efficiently convert parallel data into a serial output stream, making it a fundamental component in applications requiring data expansion, serial communication, or input pin multiplication on microcontrollers.

A primary feature of this device is its asynchronous parallel data load capability. When the parallel load input (`PL`) is held low, the data present at the eight parallel inputs (D0 to D7) is loaded directly into the register independently of the clock signals. This allows for rapid capture of a data snapshot. For shifting the data out serially, the `PL` input is set high. The register then shifts the data one bit per clock cycle towards the serial output (Q7). The shifting operation is synchronized by a low-power, complementary clock scheme (CP and `CP`), providing designers with flexibility in clocking. An additional serial data input (DS) allows for easy cascading of multiple devices to create longer shift registers, such as 16-bit or 24-bit chains, without additional logic.

Housed in a robust SOIC-16 package, the MC74HC165ADR2G is designed for automated assembly processes and offers a balance of compact size and ease of handling. Its HC CMOS technology ensures it operates with wide operating voltage ranges from 2.0V to 6.0V, enabling compatibility with various logic levels and system voltages while maintaining low power consumption and high noise immunity typical of CMOS technology.

Typical applications for this shift register are extensive. It is exceptionally useful for reading a large number of digital sensors or switches (like button matrices or DIP switches) using only a few GPIO pins on a microcontroller (MCU). This is crucial in complex systems where MCU pins are a scarce resource. Furthermore, it is commonly employed in data acquisition systems, industrial control panels, and as a peripheral interface in embedded systems to gather digital status information.

ICGOODFIND: The onsemi MC74HC165ADR2G is an exceptionally versatile and reliable solution for parallel-to-serial data conversion. Its key advantages of easy cascading for input expansion, straightforward microcontroller interfacing, and low power consumption make it an ideal choice for designers looking to optimize system cost and functionality by maximizing the utility of available MCU pins.

Keywords: Parallel-Load Shift Register, Data Acquisition, Input Expansion, Cascadable, Microcontroller Interface.