Overview
The MC74VHC138 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) that determine which one of the eight outputs (Y0 - Y7) will go Low. The device also includes enable inputs (E3, E2, and E1) to inhibit the decoding function and set all outputs to High, facilitating cascade connections and use as an address decoder for memory systems.
Key Specifications
| Parameter | Value | Unit | Conditions |
|---|---|---|---|
| Propagation Delay (tPD) | 5.7 ns (Typ) | - | VCC = 5 V |
| Supply Current (ICC) | 4 μA (Max) | - | TA = 25°C |
| Noise Immunity (VNIH, VNIL) | 28% VCC | - | - |
| Operating Voltage Range | 2 V to 5.5 V | - | - |
| Output Low Voltage (VOLP) | 0.8 V (Max) | - | - |
| ESD Performance (HBM) | > 2000 V | - | - |
| ESD Performance (Machine Model) | > 200 V | - | - |
| Chip Complexity | 122 FETs or 30.5 Equivalent Gates | - | - |
| Package Type | SOIC-16, TSSOP-16 | - | - |
| Operating Temperature Range | -55°C to +125°C | - | - |
Key Features
- High-speed operation with propagation delay of 5.7 ns (Typ) at VCC = 5 V
- Low power dissipation with ICC = 4 μA (Max) at TA = 25°C
- High noise immunity with VNIH = VNIL = 28% VCC
- Power down protection provided on inputs
- Balanced propagation delays
- Designed for 2 V to 5.5 V operating range
- Low noise with VOLP = 0.8 V (Max)
- Pin and function compatible with other standard logic families
- Latchup performance exceeds 300 mA
- ESD performance: HBM > 2000 V; Machine Model > 200 V
- Pb-free package options available
Applications
- Address decoding for memory systems
- Cascade connections in digital circuits
- Interface between 5V and 3V systems
- High-speed digital logic circuits
- Low-power digital systems
- Embedded systems requiring high noise immunity
Q & A
- What is the primary function of the MC74VHC138?
The MC74VHC138 is a 3-to-8 decoder, which means it takes three binary select inputs and decodes them to select one of eight possible outputs.
- What is the typical propagation delay of the MC74VHC138?
The typical propagation delay is 5.7 ns at VCC = 5 V.
- What is the maximum supply current of the MC74VHC138 at 25°C?
The maximum supply current is 4 μA at TA = 25°C.
- What is the operating voltage range of the MC74VHC138?
The operating voltage range is from 2 V to 5.5 V.
- How does the MC74VHC138 handle noise immunity?
The device has high noise immunity with VNIH = VNIL = 28% VCC.
- What are the ESD performance specifications of the MC74VHC138?
The ESD performance is > 2000 V for HBM and > 200 V for the Machine Model.
- What types of packages are available for the MC74VHC138?
The device is available in SOIC-16 and TSSOP-16 packages.
- Is the MC74VHC138 Pb-free?
Yes, the device is available in Pb-free packages.
- What is the operating temperature range of the MC74VHC138?
The operating temperature range is from -55°C to +125°C.
- How does the MC74VHC138 facilitate cascade connections?
The device includes enable inputs (E3, E2, and E1) to ease cascade connections and use as an address decoder for memory systems.
