74LS166 8-bit Shift Register, Parallel Load


The 74LS series of integrated circuits (ICs) was one of the most popular logic families of transistor-transistor logic (TTL) logic chips. 74LS series is a bipolar, low-power Schottky IC. 74LS166 parallel-in or serial-in, serial-out shift registers have a complexity of 77 equivalent gates on a monolithic chip. They feature gated clock inputs and an overriding clear input.

74LS166 Features

  • 8-Bit Shift Register which Can Shift Either Serial In or Parallel In Date
  • Clamping Input Diodes
  • Direct Overriding Clear
  • Clock Frequency up to 35MHz
  • Standard TTL Switching Voltages

74LS166 Specifications

Supply Voltage4.75 – 5.25Vdc
Maximum Clock Frequency40Mhz
Power Dissipation2mW/gate @100kHz
Minimum Output Current8mA
Propagation Delay10nS
Fan Out (TTL Loads)20

74LS166 Pinout Diagram

74LS166 Pin Description

Pin NoPin NameDescription
1SISerial Input
2AParallel Input
3BParallel Input
4CParallel Input
5DParallel Input
6CIClock Inhibit Pin
7CLKClock Pin
9CLRClear Pin
10EParallel Input
11FParallel Input
12GParallel Input
13QHOutput Pin
14HParallel Input H
15LOAD/SHIFTShift/Load Pin
16VCCPositive Supply


  • The shift registers are used for temporary data storage.
  • The shift registers are also used for data transfer and data manipulation.
  • The serial-in serial-out and parallel-in parallel-out shift registers are used to produce time delay to digital circuits.

74LS166 Alternative Equivalent


Download 74LS166 8-bit Shift Register, Parallel Load Datasheet from the link given below.