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. 74LS194 the bidirectional shift register is designed to incorporate virtually all of the features a system designer may want in a shift register; they feature parallel inputs, parallel outputs, right-shift, and left-shift serial inputs, operating-mode-control inputs, and a direct overriding clear line

74LS194 Features
- Parallel Inputs and Outputs
- Four Operating Modes, Synchronous, Right Shift, Left Shift and Pause
- High Speed up to 25MHz
- Positive Edge Triggered Clocking
- Standard TTL Switching Voltages
74LS194 Specifications
| Supply Voltage | 4.75 – 5.25Vdc |
| Maximum Clock Frequency | 40Mhz |
| Power Dissipation | 2mW/gate @100kHz |
| Minimum Output Current | 8mA |
| Propagation Delay | 10nS |
| Fan Out (TTL Loads) | 20 |
74LS194 Pinout Diagram

74LS194 Pin Description
| Pin No | Pin Name | Description |
| 1 | CLR’ | Clear Pin |
| 2 | SR SER | Shift Right Serial Input |
| 3 | A | Parallel Input |
| 4 | B | Parallel Input |
| 5 | C | Parallel Input |
| 6 | D | Parallel Input |
| 7 | SL SER | Shift Left Serial Input |
| 8 | GND | Ground |
| 9 | S0 | Serial Pin |
| 10 | S1 | Serial Pin |
| 11 | CLK | Clock Pin |
| 12 | QD | Output Pin |
| 13 | QC | Output Pin |
| 14 | QB | Output Pin |
| 15 | QA | Output Pin |
| 16 | VCC | Positive Supply |
Applications
- 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.
74LS194 Alternative Equivalent
Download 74LS194 4-bit Bi-directional Shift Register Datasheet from the link given below.




