Overview
The SN74HCT138DR is a 3-line to 8-line decoder/demultiplexer produced by Texas Instruments. This device is designed for high-performance memory-decoding and data-routing applications, particularly where very short propagation delay times are crucial. It operates within a voltage range of 4.5 V to 5.5 V, making it compatible with a variety of system designs.
The SN74HCT138DR is part of the HCT (High-Speed CMOS) family, which is TTL (Transistor-Transistor Logic) voltage compatible, ensuring seamless integration with existing TTL-based systems. The device features low power consumption and high-speed operation, making it ideal for applications requiring fast data processing and minimal system delay.
Key Specifications
| Parameter | Unit | Min | Nom | Max |
|---|---|---|---|---|
| VCC (Supply Voltage) | V | 4.5 | 5 | 5.5 |
| VIH (High-level Input Voltage) | V | 2 | 2 | 2 |
| VIL (Low-level Input Voltage) | V | 0.8 | 0.8 | 0.8 |
| VOH (High-level Output Voltage) | V | 3.98 | 4.3 | 4.499 |
| VOL (Low-level Output Voltage) | V | 0.17 | 0.26 | 0.4 |
| ICC (Supply Current) | μA | 8 | - | 80 |
| tpd (Propagation Delay Time) | ns | - | 17 | - |
| TA (Operating Free-Air Temperature) | °C | -40 | - | 85 |
Key Features
- Operating voltage range of 4.5 V to 5.5 V
- Outputs can drive up to 10 LSTTL loads
- Low power consumption, with a maximum supply current (ICC) of 80 μA
- Typical propagation delay time (tpd) of 17 ns
- ±4-mA output drive at 5 V
- Low input current of 1 μA max
- Inputs are TTL-voltage compatible
- Designed specifically for high-speed memory decoders and data-transmission systems
- Incorporates three enable inputs to simplify cascading and/or data reception
Applications
The SN74HCT138DR is particularly suited for high-performance memory-decoding and data-routing applications. It is ideal for use in:
- High-speed memory systems where minimal system delay is critical
- Data transmission systems requiring fast data processing
- Cascaded decoder applications where multiple decoders need to be connected
- Systems that require TTL-compatible logic levels
Q & A
- What is the operating voltage range of the SN74HCT138DR?
The operating voltage range is 4.5 V to 5.5 V.
- How many LSTTL loads can the outputs of the SN74HCT138DR drive?
The outputs can drive up to 10 LSTTL loads.
- What is the typical propagation delay time of the SN74HCT138DR?
The typical propagation delay time (tpd) is 17 ns.
- What is the maximum supply current (ICC) of the SN74HCT138DR?
The maximum supply current (ICC) is 80 μA.
- Are the inputs of the SN74HCT138DR TTL-voltage compatible?
Yes, the inputs are TTL-voltage compatible.
- What is the operating free-air temperature range of the SN74HCT138DR?
The operating free-air temperature range is -40°C to 85°C.
- How many enable inputs does the SN74HCT138DR have?
The device incorporates three enable inputs.
- What are the common applications of the SN74HCT138DR?
It is commonly used in high-speed memory systems, data transmission systems, and cascaded decoder applications.
- What is the package type of the SN74HCT138DR?
The SN74HCT138DR is available in SOIC-16 package.
- What is the maximum output current of the SN74HCT138DR?
The maximum continuous output current is ±25 mA.
