Overview
The CD74HC238EE4, produced by Texas Instruments, is a 3-to-8 line decoder/demultiplexer integrated circuit. This device is part of the HC (High-Speed CMOS) logic family and is designed for high-speed applications. It features three address select inputs (A2, A1, and A0) and three enable inputs (G2, G1, and G0) that simplify cascading and facilitate demultiplexing. The CD74HC238 is particularly useful in memory address decoding or data routing applications.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| VCC (Supply Voltage Range) | 2 | 6 | V | |
| VI (Input Voltage Range) | 0 | VCC | V | |
| VO (Output Voltage Range) | 0 | VCC | V | |
| TA (Operating Temperature Range) | -55 | 125 | °C | |
| tpd (Address to Output Propagation Delay) | 13 | 45 | ns (at VCC = 5V, CL = 50pF) | |
| tt (Output Transition Time) | 13 | 22 | ns (at VCC = 5V, CL = 50pF) | |
| Cpd (Power Dissipation Capacitance) | 67 | pF (at CL = 15pF) | ||
| Ci (Input Capacitance) | 10 | pF |
Key Features
- Select one of eight data outputs: Active high for '238.
- I/O port or memory selector.
- Three enable inputs to simplify cascading.
- Typical propagation delay of 13 ns at VCC = 5 V, CL = 15 pF, TA = 25°C.
- Fanout: Bus driver outputs support 15 LSTTL loads, standard outputs support 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 applications.
- I/O port selection.
- Demultiplexing functions.
- High-speed digital circuits requiring low power consumption.
Q & A
- What is the primary function of the CD74HC238?
The CD74HC238 is a 3-to-8 line decoder/demultiplexer, primarily used for memory address decoding or data routing applications.
- What are the operating voltage ranges for the CD74HC238?
The operating voltage range for the CD74HC238 is from 2 V to 6 V.
- How many enable inputs does the CD74HC238 have?
The CD74HC238 has three enable inputs (G2, G1, and G0).
- What is the typical propagation delay of the CD74HC238?
The typical propagation delay is 13 ns at VCC = 5 V, CL = 15 pF, and TA = 25°C.
- What is the fanout capability of the CD74HC238?
The bus driver outputs can support 15 LSTTL loads, while standard outputs can support 10 LSTTL loads.
- What is the operating temperature range of the CD74HC238?
The operating temperature range is from -55°C to 125°C.
- Does the CD74HC238 have high noise immunity?
- Is the CD74HC238 compatible with LSTTL logic?
- What are the common applications of the CD74HC238?
- How does the CD74HC238 handle power consumption?
