Overview
The SN74HCT138NSR 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 that require very short propagation delay times. It is particularly useful in high-speed memory systems where it can minimize the effects of system decoding, ensuring that the delay times introduced by the decoders are negligible when used with fast enable circuits and high-speed memories.
Key Specifications
| Parameter | Unit | Min | Max | |
|---|---|---|---|---|
| VCC (Supply voltage) | V | 4.5 | 5 | 5.5 |
| VIH (High-level input voltage) | V | 2 | - | 2 |
| VIL (Low-level input voltage) | V | 0.8 | - | 0.8 |
| VOH (High-level output voltage) | V | 4.4 | 4.4 | 4.499 |
| VOL (Low-level output voltage) | V | 0.1 | 0.1 | 0.4 |
| ICC (Supply current) | μA | 8 | - | 80 |
| tpd (Propagation delay time) | ns | 17 | - | 32 |
| 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.
- Incorporate three enable inputs to simplify cascading and/or data reception.
Applications
The SN74HCT138NSR is primarily used in high-performance memory-decoding and data-routing applications. It is particularly useful in:
- High-speed memory systems to minimize system decoding delays.
- Data transmission systems requiring fast enable circuits.
- Cascading and demultiplexing applications due to its three enable inputs.
Q & A
- What is the operating voltage range of the SN74HCT138NSR?
The operating voltage range is from 4.5 V to 5.5 V.
- How many LSTTL loads can the outputs of the SN74HCT138NSR drive?
The outputs can drive up to 10 LSTTL loads.
- What is the maximum supply current (ICC) of the SN74HCT138NSR?
The maximum supply current is 80 μA.
- What is the typical propagation delay time (tpd) of the SN74HCT138NSR?
The typical propagation delay time is 17 ns.
- What is the output drive capability of the SN74HCT138NSR at 5 V?
The output drive capability is ±4 mA at 5 V.
- Are the inputs of the SN74HCT138NSR TTL-Voltage compatible?
Yes, the inputs are TTL-Voltage compatible.
- What is the purpose of the three enable inputs on the SN74HCT138NSR?
The three enable inputs simplify cascading and/or data reception.
- In what types of applications is the SN74HCT138NSR commonly used?
It is commonly used in high-speed memory-decoding and data-routing applications.
- What is the operating temperature range of the SN74HCT138NSR?
The operating temperature range is from -40°C to 85°C.
- How many output lines can the SN74HCT138NSR select?
The device can select one of eight output lines based on the conditions at the binary-select inputs and the three enable inputs.
