Overview
The CD74HCT138MTE4 is a 3-to-8 line decoder/demultiplexer integrated circuit produced by Texas Instruments. This device is part of the 74HCT series, which is known for its high-speed CMOS logic and compatibility with TTL (Transistor-Transistor Logic) inputs. The CD74HCT138 is well-suited for applications such as memory address decoding or data routing.
The device features three address select inputs (A2, A1, and A0) and three enable inputs (G2, G1, and G0) to simplify cascading and demultiplexing operations. When any of the enable inputs are active, all outputs are forced into the high state, making it versatile for various digital circuit designs.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Package / Case | 16-SOIC (0.154", 3.90mm Width) | |
| Number of Pins | 16 | |
| Operating Temperature | -55°C to 125°C | °C |
| Voltage Supply Range | 4.5V to 5.5V | V |
| Input Voltage | 0 to VCC | V |
| Output Voltage | 0 to VCC | V |
| Input Rise and Fall Time | 1000 ns (VCC = 2V), 500 ns (VCC = 4.5V), 400 ns (VCC = 6V) | ns |
| Propagation Delay (Address to Output) | 35 ns to 53 ns (CL = 50pF) | ns |
| Output Transition Time | 15 ns to 22 ns (CL = 15pF) | ns |
| Power Dissipation Capacitance | 67 pF (CL = 15pF) | pF |
| Input Capacitance | 10 pF | pF |
Key Features
- Select one of eight data outputs: Active low for '138 and active high for '238.
- Three enable inputs (G2, G1, and G0) to simplify cascading and demultiplexing.
- Typical propagation delay of 13 ns at VCC = 5 V, CL = 15 pF, TA = 25°C.
- Fanout: Bus driver outputs can handle 15 LSTTL loads, and standard outputs can handle 10 LSTTL loads.
- Wide operating temperature range: -55°C to 125°C.
- Balanced propagation delay and transition times.
- Significant power reduction compared to LSTTL logic ICs.
- HC types: 2 V to 6 V operation, high noise immunity.
- HCT types: 4.5-V to 5.5-V operation, direct LSTTL input logic compatibility.
Applications
- Memory address decoding.
- Data routing in digital circuits.
- I/O port or memory selector applications.
- Demultiplexing functions in various digital systems.
- Cascading in larger decoder/demultiplexer networks.
Q & A
- What is the primary function of the CD74HCT138MTE4?
The primary function is to act as a 3-to-8 line decoder/demultiplexer.
- What are the operating voltage ranges for the CD74HCT138MTE4?
The operating voltage range is 4.5V to 5.5V.
- What is the package type of the CD74HCT138MTE4?
The package type is 16-SOIC (0.154", 3.90mm Width).
- How many enable inputs does the CD74HCT138MTE4 have?
It has three enable inputs (G2, G1, and G0).
- What is the typical propagation delay of the CD74HCT138MTE4?
The typical propagation delay is 13 ns at VCC = 5 V, CL = 15 pF, TA = 25°C.
- What is the fanout capability of the CD74HCT138MTE4?
Bus driver outputs can handle 15 LSTTL loads, and standard outputs can handle 10 LSTTL loads.
- What is the operating temperature range of the CD74HCT138MTE4?
The operating temperature range is -55°C to 125°C.
- Is the CD74HCT138MTE4 compatible with TTL inputs?
Yes, it is compatible with TTL inputs.
- What are some common applications of the CD74HCT138MTE4?
Common applications include memory address decoding, data routing, and demultiplexing functions.
- How does the CD74HCT138MTE4 handle cascading?
The device simplifies cascading through its three enable inputs (G2, G1, and G0).
