SLUSCK0G November   2017  – November 2024 UCC21220 , UCC21220A

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  Power Ratings
    6. 6.6  Insulation Specifications
    7. 6.7  Safety-Limiting Values
    8. 6.8  Electrical Characteristics
    9. 6.9  Switching Characteristics
    10. 6.10 Thermal Derating Curves
    11. 6.11 Typical Characteristics
  8. 7 Parameter Measurement Information
    1. 7.1 Minimum Pulses
    2. 7.2 Propagation Delay and Pulse Width Distortion
    3. 7.3 Rising and Falling Time
    4. 7.4 Input and Disable Response Time
    5. 7.5 Power-up UVLO Delay to OUTPUT
    6. 7.6 CMTI Testing
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 VDD, VCCI, and Under Voltage Lock Out (UVLO)
      2. 8.3.2 Input and Output Logic Table
      3. 8.3.3 Input Stage
      4. 8.3.4 Output Stage
      5. 8.3.5 Diode Structure in UCC21220 and UCC21220A
    4. 8.4 Device Functional Modes
      1. 8.4.1 Disable Pin
  10. 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
        1. 9.2.2.1 Designing INA/INB Input Filter
        2. 9.2.2.2 Select External Bootstrap Diode and its Series Resistor
        3. 9.2.2.3 Gate Driver Output Resistor
        4. 9.2.2.4 Estimating Gate Driver Power Loss
        5. 9.2.2.5 Estimating Junction Temperature
        6. 9.2.2.6 Selecting VCCI, VDDA/B Capacitor
          1. 9.2.2.6.1 Selecting a VCCI Capacitor
          2. 9.2.2.6.2 Selecting a VDDA (Bootstrap) Capacitor
          3. 9.2.2.6.3 Select a VDDB Capacitor
        7. 9.2.2.7 Application Circuits with Output Stage Negative Bias
      3. 9.2.3 Application Curves
  11. 10Power Supply Recommendations
  12. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Component Placement Considerations
      2. 11.1.2 Grounding Considerations
      3. 11.1.3 High-Voltage Considerations
      4. 11.1.4 Thermal Considerations
    2. 11.2 Layout Example
  13. 12Device and Documentation Support
    1. 12.1 Third-Party Products Disclaimer
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    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
  14. 13Revision History
  15. 14Mechanical, Packaging, and Orderable Information

9.2.2.5 Estimating Junction Temperature

The junction temperature (TJ) of the UCC21220 and UCC21220A can be estimated with Equation 17:

Equation 17. UCC21220 UCC21220A

where

  • TC is the UCC21220 and UCC21220A case-top temperature measured with a thermocouple or some other instrument, ψJT is the junction-to-top characterization parameter from the Section 6.4 table. Importantly, ψJT is developed based on JEDEC standard PCB board and it is subject to change when the PCB board layout is different.

Using the junction-to-top characterization parameter (ΨJT) instead of the junction-to-case thermal resistance (RΘJC) can greatly improve the accuracy of the junction temperature estimation. The majority of the thermal energy of most ICs is released into the PCB through the package leads, whereas only a small percentage of the total energy is released through the top of the case (where thermocouple measurements are usually conducted). RΘJC can only be used effectively when most of the thermal energy is released through the case, such as with metal packages or when a heatsink is applied to an IC package. In all other cases, use of RΘJC will inaccurately estimate the true junction temperature. ΨJT is experimentally derived by assuming that the amount of energy leaving through the top of the IC will be similar in both the testing environment and the application environment. As long as the recommended layout guidelines are observed, junction temperature estimates can be made accurately to within a few degrees Celsius.

For more information, see the Section 11.1 and Semiconductor and IC Package Thermal Metrics Application Report.