Overview
The SN74HCS138 is a high-speed silicon gate CMOS decoder/demultiplexer produced by Texas Instruments. It is well-suited for memory address decoding or data routing applications. The device features three address select inputs (A2, A1, and A0) and three strobe inputs (G2, G1, and G0), allowing for flexible control over its eight outputs. The SN74HCS138 includes Schmitt-trigger inputs, which provide additional noise margin and allow for slow or noisy input signals. This makes it highly reliable in various digital circuit applications.
Key Specifications
| Parameter | Min | |||
|---|---|---|---|---|
| VCC Supply Voltage | 2 | 5 | 6 | V |
| Input Voltage | 0 | - | VCC | V |
| Ambient Temperature | -40 | - | 125 | °C |
| Input Leakage Current | - | ±100 | ±1000 | nA |
| Supply Current (ICC) | - | 0.1 | 2 | µA |
| Output Drive at 6 V | - | ±7.8 | - | mA |
| Propagation Delay (tpd) | 7 | 11 | 16 | ns (at VCC = 6 V) |
| Transition Time (tt) | 4 | 7 | - | ns (at VCC = 6 V) |
Key Features
- Wide Operating Voltage Range: 2 V to 6 V
- Schmitt-Trigger Inputs: Allow for slow or noisy input signals and provide additional noise margin
- Low Power Consumption: Typical ICC of 100 nA and typical input leakage current of ±100 nA
- High Output Drive: ±7.8-mA output drive at 6 V
- Extended Ambient Temperature Range: –40°C to +125°C
- Balanced CMOS Push-Pull Outputs: Ensures stable output levels
Applications
- Memory Device Selection with Shared Data Bus: Ideal for solid-state memory applications where multiple devices share a data bus
- Chip Select Applications: Reduces the number of outputs required for chip select functions
- Data Routing: Facilitates routing data to specific outputs based on input conditions
Q & A
- What is the primary function of the SN74HCS138?
The SN74HCS138 is a three-to-eight decoder/demultiplexer, used for memory address decoding or data routing applications.
- What is the operating voltage range of the SN74HCS138?
The operating voltage range is from 2 V to 6 V.
- What is the significance of Schmitt-trigger inputs in the SN74HCS138?
Schmitt-trigger inputs allow for slow or noisy input signals and provide additional noise margin.
- How many address select inputs and strobe inputs does the SN74HCS138 have?
The device has three address select inputs (A2, A1, A0) and three strobe inputs (G2, G1, G0).
- What is the typical supply current (ICC) of the SN74HCS138?
The typical supply current (ICC) is 0.1 µA.
- What is the maximum output drive current at 6 V?
The maximum output drive current at 6 V is ±7.8 mA.
- What is the ambient temperature range for the SN74HCS138?
The ambient temperature range is from –40°C to +125°C.
- How does the SN74HCS138 handle cascading and demultiplexing?
The device simplifies cascading and demultiplexing through its three strobe inputs (G2, G1, G0), which can force all outputs into the high state when active.
- What are some common applications of the SN74HCS138?
Common applications include memory device selection with shared data bus, chip select applications, and data routing.
- What are the package options available for the SN74HCS138?
The device is available in TSSOP, SOIC, WQFN, and SOT-23 packages.
