SCES538H January   2004  – August 2026 SN74LVC1G38

PRODUCTION DATA  

  1.   1
  2.   2
  3. 1 Features
  4. 2 Applications
  5. 3 Description
  6. 4 Pin Configuration and Functions
  7. 5 Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  ESD Ratings
    3. 5.3  Recommended Operating Conditions
    4. 5.4  Thermal Information
    5. 5.5  Electrical Characteristics
    6. 5.6  Switching Characteristics, CL = 15pF
    7. 5.7  Switching Characteristics, CL = 30pF or 50pF, –40°C to +85°C
    8. 5.8  Switching Characteristics, CL = 30pF or 50pF, –40°C to +125°C
    9. 5.9  Operating Characteristics
    10. 5.10 Typical Characteristics
  8. 6 Parameter Measurement Information
  9.   19
  10. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 High-Drive Open-Drain Output
      2. 7.3.2 Standard CMOS Inputs
      3. 7.3.3 Clamp Diodes
      4. 7.3.4 Partial Power Down (Ioff)
      5. 7.3.5 Over-Voltage Tolerant Inputs
      6. 7.3.6 Up Translation and Down Translation Capable Outputs
    4. 7.4 Device Functional Modes
  11. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  12. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  13. 10Revision History
  14. 11Mechanical, Packaging, and Orderable Information

8.4.1 Layout Guidelines

When using multiple bit logic devices, inputs must not float. In many cases, functions or parts of functions of digital logic devices are unused. Some examples are when only two inputs of a triple-input AND gate are used, or when only 3 of the 4-buffer gates are used. Such input pins must not be left unconnected because the undefined voltages at the outside connections result in undefined operational states.

Specified in Figure 8-3 are rules that must be observed under all circumstances. All unused inputs of digital logic devices must be connected to a high or low bias to prevent them from floating. The logic level that must be applied to any particular unused input depends on the function of the device. Generally they are tied to GND or VCC, whichever makes more sense or is more convenient.

Even low data rate digital signals can have high frequency signal components due to fast edge rates. When a printed-circuit board (PCB) trace turns a corner at a 90° angle, a reflection can occur. A reflection occurs primarily because of the change of width of the trace. At the apex of the turn, the trace width increases to 1.414 times the width. This increase upsets the transmission-line characteristics, especially the distributed capacitance and self–inductance of the trace which results in the reflection. Not all PCB traces can be straight and therefore some traces must turn corners. Figure 8-4 shows progressively better techniques of rounding corners. Only the last example (BEST) maintains constant trace width and minimizes reflections.