SCLS107G December   1982  – October 2021 SN54HC138 , SN74HC138

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings: SN74HC138
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information: SN74HC138
    5. 6.5  Thermal Information: SN54HC138
    6. 6.6  Electrical Characteristics
    7. 6.7  Electrical Characteristics: SN74HC138
    8. 6.8  Electrical Characteristics: SN54HC138
    9. 6.9  Switching Characteristics
    10. 6.10 Switching Characteristics: SN74HC138
    11. 6.11 Switching Characteristics: SN54HC138
    12. 6.12 Typical Characteristic
  7. 7 Parameter Measurement Information
    1.     21
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Related Links
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Support Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • W|16
  • J|16
Thermal pad, mechanical data (Package|Pins)
Orderable Information

11.1 Layout Guidelines

Reflections and matching are closely related to loop antenna theory, but different enough to warrant their own discussion. When a PCB trace turns a corner at a 90° angle, a reflection can occur. This is primarily due to the change of width of the trace. At the apex of the turn, the trace width is increased to 1.414 times its width. This upsets the transmission line characteristics, especially the distributed capacitance and self–inductance of the trace (resulting in the reflection). It is a given that not all PCB traces can be straight, and so they have to turn corners. Figure 11-1 shows progressively better techniques of rounding corners. Only the last example maintains constant trace width and minimizes reflections.