74LS138 3 to 8 Decoder/Demultiplexer
Package SOIC Series 74LS
74LS138 overview
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 74LS138, decode one of eight lines dependent on the conditions at the three binary select inputs and the three enable inputs. Two active-low and one active-high enable inputs to reduce the need for external gates or inverters when expanding
Key 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
Datasheet
138.pdf
74LS138 features
- Decodes One-of-Eight Lines 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
74LS138 pinout
| Pin | Name | Description |
|---|---|---|
| 1 | A0 | Data Input Select Pin |
| 2 | A1 | Data Input Select Pin |
| 3 | A2 | Data Input Select Pin |
| 4 | E1 | Enable Pin |
| 5 | E2 | Enable Pin |
| 6 | E3 | Enable Pin |
| 7 | O7 | Output 7 |
| 8 | GND | Ground |
| 9 | O6 | Output 6 |
| 10 | O5 | Output 5 |
| 11 | O4 | Output 4 |
| 12 | O3 | Output 3 |
| 13 | O2 | Output 2 |
| 14 | O1 | Output 1 |
| 15 | O0 | Output 0 |
| 16 | VCC | Positive Supply |
74LS138 applications
- Decoders are used to input data to a specified output line as is done in addressing core memory where input data is to be stored in a specified memory location.
- It is used in code conversions.
- In high-performance memory systems, this decoder can be used to minimize the effects of system decoding
More about 74LS138
74LS138 Alternative Equivalent
74LS137
Comments 0
Leave a comment