Overview
The MC74VHCT138ADR2G is an advanced high-speed CMOS 3-to-8 decoder fabricated with silicon gate CMOS technology. It is designed to achieve high-speed operation similar to equivalent Bipolar Schottky TTL while maintaining the low power dissipation characteristic of CMOS devices. The decoder is enabled by three binary select inputs (A0 - A2), which determine which one of the eight outputs (Y0 - Y7) will go low. The device also features enable inputs (E3, E2bar, and E1bar) that inhibit the decoding function and set all outputs high when E3 is low or either E2bar or E1bar is high. This makes it suitable for cascade connections and use as an address decoder in memory systems. Additionally, the VHCT inputs are compatible with TTL levels, and the device can act as a level converter for interfacing 3.3V to 5.0V systems.
Key Specifications
| Attribute | Value |
|---|---|
| Logic Family | 74VHCT |
| Logic Function | Decoder |
| Demultiplexing Capability | 3-of-8 |
| Number of Elements per Chip | 1 |
| Pin Count | 16 |
| Number of Input Enables per Element | 3 |
| Output Type | 3 State |
| Polarity | Inverting |
| Mounting Type | Surface Mount |
| Package Type | SOIC |
| Dimensions | 10 x 4 x 1.5mm |
| Maximum Operating Supply Voltage | 5.5 V |
| Minimum Operating Temperature | -55 °C |
| Maximum Operating Temperature | +125 °C |
| Minimum Operating Supply Voltage | 3 V |
| Propagation Delay (Typical at VCC = 5.0 V) | 7.6 ns |
| Power Dissipation (Maximum at TA = 25°C) | 4 μA |
Key Features
- High Speed: Achieves propagation delays similar to Bipolar Schottky TTL devices.
- Low Power Dissipation: Maximum current consumption of 4 μA at 25°C.
- TTL-Compatible Inputs: Compatible with TTL logic levels (VIL = 0.8 V, VIH = 2.0 V).
- Power Down Protection: Input and output structures provide protection against supply voltage - input/output voltage mismatch, battery backup, and hot insertion.
- Balanced Propagation Delays: Ensures consistent timing across all outputs.
- Operating Range: Designed for 4.5 V to 5.5 V operating range.
- Pin and Function Compatibility: Compatible with other standard logic families).
- Latchup Performance: Exceeds 300 mA).
- ESD Performance: Human Body Model > 2000 V; Machine Model > 200 V).
Applications
- Computer Memory Systems: Used as address decoders).
- Transmission Systems: In satellite and other communication systems).
- Time Division Multiplexing Systems: For multiplexing data streams).
- Frequency Multiplexing Systems: For frequency division multiplexing).
- A/D and D/A Converters: For digital-to-analog and analog-to-digital conversions).
- Boolean Function Implementation: For implementing logical functions with multiple variables).
- Data Collection Systems: For data acquisition and processing).
- Audio and Video Transmission: For signal processing in audio and video systems).
Q & A
- What is the primary function of the MC74VHCT138ADR2G?
The primary function is to act as a 3-to-8 decoder, determining which one of the eight outputs will go low based on the three binary select inputs (A0 - A2).
- What are the enable inputs for this decoder?
The enable inputs are E3, E2bar, and E1bar. When E3 is low or either E2bar or E1bar is high, the decoding function is inhibited and all outputs go high.
- What is the operating voltage range of the MC74VHCT138ADR2G?
The device operates within a voltage range of 4.5 V to 5.5 V.
- What is the propagation delay of the MC74VHCT138ADR2G?
The typical propagation delay at VCC = 5.0 V is 7.6 ns.
- Is the MC74VHCT138ADR2G compatible with TTL logic levels?
Yes, the VHCT inputs are compatible with TTL logic levels.
- What kind of protection does the MC74VHCT138ADR2G offer?
The device offers power down protection on inputs and outputs, protecting against supply voltage - input/output voltage mismatch, battery backup, and hot insertion.
- What is the package type of the MC74VHCT138ADR2G?
The device is supplied in a 16-pin SOIC package.
- What are some common applications of the MC74VHCT138ADR2G?
Common applications include computer memory systems, transmission systems, time division multiplexing systems, and A/D and D/A converters.
- What is the maximum operating temperature of the MC74VHCT138ADR2G?
The maximum operating temperature is +125 °C.
- Does the MC74VHCT138ADR2G have ESD protection?
Yes, the device has ESD protection with Human Body Model > 2000 V and Machine Model > 200 V.
