SCLS793B March   2020  – October 2026 SN74HCS21

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 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
    7. 5.7 Typical Characteristics
  7. 6 Parameter Measurement Information
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Balanced CMOS Push-Pull Outputs
      2. 7.3.2 CMOS Schmitt-Trigger Inputs
      3. 7.3.3 Clamp Diode Structure
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
        1. 8.2.1.1 Power Considerations
        2. 8.2.1.2 Input Considerations
        3. 8.2.1.3 Output Considerations
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

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5.4 Thermal Information

THERMAL METRIC(1) SN74HCS21 UNIT
PW (TSSOP) D (SOIC)
14 PINS 14 PINS
RθJA Junction-to-ambient thermal resistance 151.7 133.6 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 79.4 89.0 °C/W
RθJB Junction-to-board thermal resistance 94.7 89.5 °C/W
ΨJT Junction-to-top characterization parameter 25.2 45.5 °C/W
ΨJB Junction-to-board characterization parameter 94.1 89.1 °C/W
RθJC(bot) Junction-to-case (bottom) thermal resistance N/A N/A °C/W
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application note.