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. The 74LS148 encodes eight data lines to three-line (9-7-6) BCD. The implied decimal zero condition does not require an input condition because zero is encoded when all eight data lines are at a high logic level.

74LS148 Features
- Encodes Eight Data Lines to Three (octal)
- Inputs Clamped with Schottky Diodes
- Low Power
- Operating Temperature up to 70°C
- Standard TTL Switching Voltages
74LS148 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 |
74LS148 Pinout Diagram

74LS148 Pin Description
Pin No | Pin Name | Description |
1 | 4 | Data Input Pin 4 |
2 | 5 | Data Input Pin 5 |
3 | 6 | Data Input Pin 6 |
4 | 7 | Data Input Pin 7 |
5 | EI | Enable Input Pin |
6 | A2 | Output A2 |
7 | A1 | Output A1 |
8 | GND | Ground |
9 | A0 | Output A0 |
10 | 0 | Data Input Pin 0 |
11 | 1 | Data Input Pin 1 |
12 | 2 | Data Input Pin 2 |
13 | 3 | Data Input Pin 3 |
14 | GS | Output GS |
15 | E0 | Enable Output Pin |
16 | VCC | Positive Supply |
74LS148 Circuit
Below is a simple circuit of 4 to 2 Bit Encoder using logic gates (NOT, NOR, and AND).

Applications
- Speed synchronization of multiple motors in industries.
- War field flying robot with a night vision flying camera.
- A robotic vehicle with the metal detector.
- RF-based home automation system.
- Automatic health monitoring systems.
74LS148 Alternative Equivalent
74LS147
Download 74LS148 8 to 3 Priority Encoder Datasheet from the link given below.