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. 74LS91 serial-in, serial-out, and 8-bit shift registers utilize transistor-transistor logic (TTL) circuits and are composed of eight R.S master-slave flip-flops, input gating, and a clock driver. Single-rail data and input control are gated through inputs A and B and an internal inverter to form the complementary inputs to the first bit of the shift register.
74LS91 Features
- Use In Digital Computer Systems
- Use In Data-Handling Systems
- Use In Control Systems
74LS91 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 |
74LS91 Pinout Diagram
74LS91 Pin Description
| Pin No | Pin Name | Description |
| 1 | NC | Not Connected |
| 2 | NC | Not Connected |
| 3 | NC | Not Connected |
| 4 | NC | Not Connected |
| 5 | VCC | NAND Gate 2 Input 2 |
| 6 | NC | Not Connected |
| 7 | NC | Not Connected |
| 8 | NC | Not Connected |
| 9 | CLK | Clock Pin |
| 10 | GND | Ground Pin |
| 11 | B | Input Pin B |
| 12 | A | Input Pin A |
| 13 | QH | Output Pin |
| 14 | (Q’)H | Invert Output Pin |
74LS91 Circuit
Here is a simple circuit of 4 Bit Shift Register using DQ Flip Flops.
Applications
- The shift registers are used for temporary data storage.
- The shift registers are also used for data transfer and data manipulation.
74LS91 Alternative Equivalent
74LS164, 74LS165
Download 74LS91 8-Bit Shift Register Datasheet from the link given below.
