Overview
The SN74HC138DRE4, produced by Texas Instruments, is a 3-line to 8-line decoder/demultiplexer. 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 systems where fast enable circuits are employed, ensuring that the delay times of the decoders and the enable time of the memory are negligible compared to the typical access time of the memory.
Key Specifications
| Parameter | Min | Max | Unit | |
|---|---|---|---|---|
| Supply Voltage Range (VCC) | 2 | - | 6 | V |
| Propagation Delay (tpd) at VCC = 2 V | 225 | - | - | ns |
| Propagation Delay (tpd) at VCC = 4.5 V | 45 | - | - | ns |
| Propagation Delay (tpd) at VCC = 6 V | 38 | - | - | ns |
| Output Drive at 5 V | ±4 | - | - | mA |
| Low Input Current | - | - | 1 | μA |
| Continuous Output Current | - | - | ±25 | mA |
| Operating Free-Air Temperature | -40 | - | 85 | °C |
| Storage Temperature | -65 | - | 150 | °C |
Key Features
- Targeted specifically for high-speed memory decoders and data-transmission systems.
- Wide operating voltage range of 2 V to 6 V.
- Outputs can drive up to 10 LSTTL loads.
- Low power consumption, with a maximum ICC of 80 μA.
- Typical propagation delay of 15 ns at VCC = 5 V.
- ±4-mA output drive at 5 V.
- Low input current of 1 μA maximum.
- Active low outputs; the selected output is pulled LOW, while the remaining outputs are HIGH.
- Incorporates three enable inputs to simplify cascading or data reception.
Applications
- LED displays.
- Servers.
- White goods.
- Power infrastructure.
- Building automation.
- Factory automation.
Q & A
- What is the primary function of the SN74HC138DRE4?
The SN74HC138DRE4 is a 3-line to 8-line decoder/demultiplexer, designed for high-performance memory-decoding and data-routing applications.
- What is the operating voltage range of the SN74HC138DRE4?
The operating voltage range is from 2 V to 6 V.
- How many LSTTL loads can the outputs of the SN74HC138DRE4 drive?
The outputs can drive up to 10 LSTTL loads.
- What is the typical propagation delay of the SN74HC138DRE4 at VCC = 5 V?
The typical propagation delay is 15 ns at VCC = 5 V.
- What is the maximum input current of the SN74HC138DRE4?
The maximum input current is 1 μA.
- How do the enable inputs function in the SN74HC138DRE4?
The device incorporates three enable inputs: two active-low and one active-high. All three enable inputs must be active for the output to be enabled.
- What are some common applications of the SN74HC138DRE4?
Common applications include LED displays, servers, white goods, power infrastructure, building automation, and factory automation.
- What is the maximum continuous output current of the SN74HC138DRE4?
The maximum continuous output current is ±25 mA.
- What is the operating free-air temperature range of the SN74HC138DRE4?
The operating free-air temperature range is from -40°C to 85°C.
- How does the SN74HC138DRE4 minimize system decoding delays in high-performance memory systems?
The device minimizes system decoding delays by ensuring that the delay times of the decoders and the enable time of the memory are usually less than the typical access time of the memory.
