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. 74LS125 bus buffers feature three-state outputs that, when enabled, have the low impedance characteristics of a TTL output with additional drive capability at high logic levels to permit driving heavily loaded bus lines without external pullup resistors.

74LS125 Features
- Four Independent Non-Inverting Buffer Gates
- Enabled Mode
- Fast Switching Times
- Operating Temperature up to 70°C
- Standard TTL Switching Voltages
74LS125 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 |
74LS125 Pinout Diagram

74LS125 Pin Description
Pin No | Pin Name | Description |
1 | E’ | Invert Enable Pin Of Buffer 1 |
2 | D | Data Input Of Buffer 1 |
3 | O | Output Of Buffer 1 |
4 | E’ | Invert Enable Pin Of Buffer 2 |
5 | D | Data Input Of Buffer 2 |
6 | O | Output Of Buffer 2 |
7 | GND | Ground |
8 | O | Output Of Buffer 3 |
9 | D | Data Input Of Buffer 3 |
10 | E’ | Invert Enable Pin Of Buffer 3 |
11 | O | Output Of Buffer 4 |
12 | D | Data Input Of Buffer 4 |
13 | E’ | Invert Enable Pin Of Buffer 4 |
14 | VCC | Positive Supply |
74LS125 Circuit
Applications
- A buffer or a voltage buffer is used to isolate input from the output. The buffer’s output state mirrors the input state.
74LS125 Alternative Equivalent
74LS126
Download 74LS125 Quad Bus Buffer Negative Enable Tri-State Datasheet from the link given below.