SLUSCE9B June   2017  – March 2020

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
      2.      Typical Propagation Delay Comparison
  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
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Dynamic Electrical Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 VDD and Under Voltage Lockout
      2. 7.3.2 Input and Output Logic Table
      3. 7.3.3 Input Stage
      4. 7.3.4 Output Stage
      5. 7.3.5 Level Shift
      6. 7.3.6 Low Propagation Delays and Tightly Matched Outputs
      7. 7.3.7 Parasitic Diode Structure
    4. 7.4 Device Functional Modes
      1. 7.4.1 Minimum Input Pulse Operation
      2. 7.4.2 Output Interlock and Dead Time
      3. 7.4.3 Operation Under 100% Duty Cycle Condition
      4. 7.4.4 Operation Under Negative HS Voltage Condition
  8. 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
        1. 8.2.2.1 Selecting HI and LI Low Pass Filter Components (RHI, RLI, CHI, CLI)
        2. 8.2.2.2 Selecting Bootstrap Capacitor (CBOOT)
        3. 8.2.2.3 Selecting VDD Bypass/Holdup Capacitor (CVDD) and Rbias
        4. 8.2.2.4 Selecting Bootstrap Resistor (RBOOT)
        5. 8.2.2.5 Selecting Gate Resistor RON/ROFF
        6. 8.2.2.6 Selecting Bootstrap Diode
        7. 8.2.2.7 Estimate the UCC27712 Power Losses (PUCC27712)
        8. 8.2.2.8 Estimating Junction Temperature
        9. 8.2.2.9 Operation With IGBT's
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Related Links
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

8.2.2.8 Estimating Junction Temperature

The junction temperature can be estimated with:

Equation 22. UCC27712 qu22_slusce9.gif

where

  • TC is the UCC27712 case-top temperature measured with a thermocouple or some other instrument. and
  • ѰJT is the junction-to-top characterization parameter from the Thermal Information table. Importantly.

Using the junction-to-top characterization parameter (ѰJT) instead of the junction-to-case thermal resistance (RθJC) can greatly improve the accuracy of estimating the junction temperature. The majority of the power dissipation of most devices is released into the PCB through the package leads, whereas only a small percentage of the total dissipation is released through the top of the case (where thermocouple measurements are usually taken). RθJC can only be used effectively when most of the thermal energy is released through the case, such as with metal packages or a heatsink is applied to the device package. In other cases RθJC will inaccurately estimate the true junction temperature of the device. ѰJT is experimentally derived by assuming the amount of thermal energy dissipated through the top of the device will be similar in both the testing environment and the application environment. As long as the recommended layout guidelines are observed, junction temperature can be estimated accurately to within a few degrees Celsius. For more information, see the Semiconductor and IC Package Thermal Metrics application report.

Additional Considerations: In the application example schematic there are 10-kΩ resistors across the gate and source terminals of FET Q1 and Q2.  These resistors are placed across these nodes to ensure FETs Q1 and Q2 are not turned on if the UCC27712 is not in place or properly soldered to the circuit board or if UCC27712 is in an unbiased state.