74164 (8-bit serial-in/parallel-out shift register)

Description

The 74164 is an 8-bit serial-in/parallel-out shift register. It is part of the 7400 series of ICs and is commonly used in digital systems for applications where you need to convert serial data to parallel data or vice versa. The IC can take in serial data (bit by bit) and output it in parallel (all bits simultaneously). It’s widely used for data storage, data transfer, and shift register applications.

74164 IC Description:

The 74164 is an 8-bit serial-in/parallel-out shift register with a clocked operation. It is designed to accept serial data at its serial input (DS) pin and shift the data into the register on the rising edge of the clock (CLK) signal. Once the data is shifted in, it can be output in parallel form from Q0 to Q7. The 74164 also includes a serial output (QH) for serial data retrieval.

Key Features:

• 8-bit Serial-in, Parallel-out Shift Register: The 74164 has 8-bit data storage, and it can shift in data serially while outputting the stored data in parallel.
• Clocked Operation: The shift register operates in synchronous mode, with data shifting occurring on the rising edge of the clock signal.
• Parallel Outputs (Q0 to Q7): The IC provides 8 parallel outputs, one for each bit of data stored in the shift register.
• Serial Output (QH): The serial output allows for the shifted data to be accessed one bit at a time.
• Shift Control: The data is shifted with each clock pulse, either to the left or right depending on the configuration of the circuit.

Pin Configuration (16-pin package):

Here’s the pinout for the 74164:

1. Pin 1 (Q0): Output bit 0 (Least Significant Bit).
2. Pin 2 (Q1): Output bit 1.
3. Pin 3 (Q2): Output bit 2.
4. Pin 4 (Q3): Output bit 3.
5. Pin 5 (Q4): Output bit 4.
6. Pin 6 (Q5): Output bit 5.
7. Pin 7 (Q6): Output bit 6.
8. Pin 8 (Q7): Output bit 7 (Most Significant Bit).
9. Pin 9 (Serial Output): QH – Serial data output.
10. Pin 10 (Shift/Load): Shift/Load input, controls whether data is shifted or loaded in parallel.
11. Pin 11 (Clock): CLK – Clock input for synchronizing the shifting of data.
12. Pin 12 (Serial Data Input): DS – Serial data input for shifting data into the register.
13. Pin 13 (Ground): Ground.
14. Pin 14 (Vcc): Supply voltage (typically 5V).
15. Pin 15 (Clear): Active-low Clear input for resetting the shift register.
16. Pin 16 (Output Enable): OE – Output enable for controlling parallel outputs.

How It Works:

1. Serial Data Input:
   • The 74164 takes in serial data bit by bit at the DS (Serial Data Input) pin. This data is shifted into the shift register on the rising edge of the clock (CLK) signal.
2. Shifting Data:
   • Each time a clock pulse is applied, the data is shifted to the next register bit in the chain. The data that is shifted in at DS moves to the first bit of the shift register, and all the other bits move to the next position in the sequence.
   • The Shift/Load input controls whether the shift register is active in the shift operation. When Shift/Load is low, the register will shift data on each clock pulse. When Shift/Load is high, parallel loading of data can take place (when the inputs D0–D7 are connected).
3. Parallel Output:
   • The data in the shift register can be accessed in parallel from the output pins Q0 to Q7. These outputs reflect the value of the shift register after the data has been shifted in.
4. Serial Output:
   • The data can also be retrieved serially from the QH (Serial Output) pin, allowing the stored data to be read out one bit at a time.
5. Clear Function:
   • The Clear (CLR) pin is active-low. When it is low, it resets the shift register and clears all stored data (sets all bits to 0).
6. Output Enable:
   • The OE (Output Enable) pin controls the parallel outputs. When OE is low, the parallel outputs (Q0–Q7) are enabled and will show the current data stored in the shift register. When OE is high, the outputs are disabled, and the output pins will be in a high-impedance state.

Truth Table:

Applications:

1. Serial-to-Parallel Conversion: The 74164 is commonly used to convert serial data (received one bit at a time) into parallel data (all bits at once) for use in other parts of the system.
2. Data Storage: It can be used for temporary storage of data. Since it has 8-bit parallel outputs, it can hold 8 bits of data that can be read in parallel.
3. Shift Register Chains: When connected in series with other shift registers, the 74164 can be used to expand the number of bits that can be handled by the system. The serial output (QH) can be connected to the serial input of another shift register.
4. Data Transfer: It can be used in digital systems for transferring data between components that operate with different data formats (serial vs. parallel).
5. LED Driving: One common use of the 74164 is in driving multiple LEDs in a serial-to-parallel fashion. A microcontroller or other serial device can send data to the 74164, which outputs parallel signals to the LEDs.
6. Microprocessor Interfacing: The 74164 can interface with microprocessors, where data is fed in serially and output in parallel, useful for interfacing with devices that require a parallel data bus but receive data serially.
7. Signal Conversion: In systems that need to convert between serial data and parallel data, the 74164 is a critical component.

Electrical Characteristics:

• Supply Voltage (Vcc): Typically 5V (can operate in the range of 4.5V to 5.5V).
• Clock Frequency: The speed of operation (shift rate) is determined by the clock frequency. Typically, the 74164 can operate at clock speeds up to a few MHz.
• Low Power Consumption: As a CMOS device, it has low power consumption, which is beneficial for battery-powered or energy-efficient systems.