74165 - 8-Bit Parallel-In/Serial-Out Shift Register

Overview

The M54/74HC165 is a high-speed CMOS 8-bit parallel-in/serial-out (PISO) shift register fabricated using silicon gate C2MOS technology. This component is designed to provide high-speed operation while maintaining low power consumption, making it suitable for a wide range of digital applications. The device features parallel data inputs, a serial data output, and control inputs for shifting and loading data, enabling efficient data transfer and storage in digital systems.

The 74HC165 is part of the 74HC family, which is known for its compatibility with both CMOS and TTL logic levels. This ensures seamless integration into existing digital designs without requiring significant modifications. The shift register is widely used in applications requiring data serialization, such as data acquisition systems, communication interfaces, and display drivers.

Features

• High-Speed Operation: The 74HC165 operates at high speeds, making it suitable for time-critical applications.
• Low Power Consumption: Fabricated using CMOS technology, the device consumes minimal power, enhancing energy efficiency.
• 8-Bit Parallel-In/Serial-Out: Supports parallel data loading and serial data output for flexible data handling.
• Wide Operating Voltage Range: Operates within a voltage range of 2V to 6V, accommodating various digital systems.
• TTL Compatibility: Inputs and outputs are compatible with TTL logic levels, ensuring interoperability with TTL-based circuits.
• Synchronous or Asynchronous Operation: Features both synchronous and asynchronous control inputs for versatile operation modes.
• High Noise Immunity: CMOS technology provides excellent noise immunity, ensuring reliable performance in noisy environments.
• Standard Pin Configuration: Follows industry-standard pinouts for easy integration into existing designs.

Applications

The 74HC165 is a versatile component used in a variety of digital systems. Below are some common applications:

• Data Serialization: Converts parallel data into a serial stream for transmission over communication lines.
• Input Expansion: Used to expand the number of input pins in microcontroller-based systems.
• Keyboard and Switch Interfaces: Scans multiple switches or keys and transmits their states serially to a processor.
• Display Drivers: Drives LED or LCD displays by serializing data for multiplexed displays.
• Data Acquisition Systems: Captures parallel sensor data and converts it into a serial format for processing.
• Industrial Control Systems: Interfaces with multiple sensors and actuators in control applications.

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (V_CC): -0.5V to +7V
• Input Voltage (V_IN): -0.5V to V_CC + 0.5V
• Output Voltage (V_OUT): -0.5V to V_CC + 0.5V
• Operating Temperature Range: -40°C to +125°C
• Storage Temperature Range: -65°C to +150°C

Recommended Operating Conditions

• Supply Voltage (V_CC): 2V to 6V
• Input High Voltage (V_IH): 3.15V (min) at V_CC = 4.5V
• Input Low Voltage (V_IL): 1.35V (max) at V_CC = 4.5V
• Output High Current (I_OH): -4mA (max)
• Output Low Current (I_OL): 4mA (max)

Timing Characteristics

• Maximum Clock Frequency (f_CLK): 25MHz (typical at V_CC = 4.5V)
• Propagation Delay (t_PD): 15ns (max) from clock to output
• Setup Time (t_SU): 20ns (min) for data inputs before clock edge
• Hold Time (t_H): 5ns (min) for data inputs after clock edge

Package Information

The 74HC165 is available in several industry-standard packages, providing flexibility for different PCB layouts and assembly processes. Below are the common package options:

• DIP-16 (Dual In-Line Package): A through-hole package with 16 pins, suitable for prototyping and breadboarding.
• SOIC-16 (Small Outline Integrated Circuit): A surface-mount package with 16 pins, ideal for compact and high-density PCB designs.
• TSSOP-16 (Thin Shrink Small Outline Package): A smaller surface-mount variant with reduced footprint, suitable for space-constrained applications.

Pin Configuration

The 74HC165 features a 16-pin configuration with the following pin assignments:

• Pin 1 (SH/LD): Shift/Load input (active low). Controls whether data is loaded in parallel or shifted serially.
• Pin 2 (CLK): Clock input. Shifts data on the rising edge.
• Pin 3 (D7): Parallel data input bit 7 (MSB).
• Pins 4-10 (D6-D0): Parallel data input bits 6 through 0.
• Pin 11 (Q7): Serial data output. Provides the shifted-out data.
• Pin 12 (Q7'): Complementary serial output (inverted Q7).
• Pin 13 (GND): Ground reference.
• Pin 14 (SER): Serial data input. Used for daisy-chaining multiple shift registers.
• Pin 15 (CLK INH): Clock inhibit input (active low). Disables the clock when low.
• Pin 16 (V_CC): Positive supply voltage.

Conclusion

The 74HC165 is a reliable and high-performance 8-bit parallel-in/serial-out shift register that offers a combination of speed, low power consumption, and versatility. Its compatibility with both CMOS and TTL logic levels, along with its robust electrical characteristics, makes it a preferred choice for a wide range of digital applications. Whether used for data serialization, input expansion, or display driving, the 74HC165 provides an efficient solution for managing parallel and serial data conversion in modern electronic systems.