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. 74LS139 comprises two individual two-line to four-line decoders in a single package. The active-low enable input can be used as a data line in demultiplexing applications.
74LS139 Features
- Two Independent Two-of-Four Decoders Based Upon the Select Inputs
- Inputs Clamped with Schottky Diodes
- Designed for Memory Decoders and Data Transmission Systems
- Operating Temperature up to 70°C
- Standard TTL Switching Voltages
74LS139 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 |
74LS139 Pinout Diagram
74LS139 Pin Description
| Pin No | Pin Name | Description |
| 1 | Ea | Decoder A Enable Pin |
| 2 | A0a | Input 0 of Decoder A |
| 3 | A1a | Input 1 of Decoder A |
| 4 | O0a | Output 0 of Decoder A |
| 5 | O1a | Output 1 of Decoder A |
| 6 | O2a | Output 2 of Decoder A |
| 7 | O3a | Output 3 of Decoder A |
| 8 | GND | Ground Pin |
| 9 | O3b | Output 3 of Decoder B |
| 10 | O2b | Output 2 of Decoder B |
| 11 | O1b | Output 1 of Decoder B |
| 12 | O0b | Output 0 of Decoder B |
| 13 | A1b | Input 1 of Decoder B |
| 14 | A0b | Input 0 of Decoder B |
| 15 | Eb | Decoder B Enable Pin |
| 16 | VCC | Positive Supply |
74LS139 Circuit
Applications
- It is used in code conversion. i.e analog to digital conversion in the analog decoder.
- It may also be used for data distribution.
- In a high-performance memory system, this decoding can be used to minimize the effect of system decoding.
74LS139 Alternative Equivalent
74LS138
Download 74LS139 2 to 4 Decoder/Demultiplexer Datasheet from the link given below.
