SLUSDE1E September   2018  – November 2024 UCC21540 , UCC21540A , UCC21541 , UCC21542

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
    1. 5.1 Pin Configuration and Functions
    2. 5.2 UCC21542 Pin 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 Insulation Characteristics 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 Programmable Dead Time
    6. 7.6 Power-Up UVLO Delay to OUTPUT
    7. 7.7 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 the UCC2154x
    4. 8.4 Device Functional Modes
      1. 8.4.1 Disable Pin
      2. 8.4.2 Programmable Dead Time (DT) Pin
        1. 8.4.2.1 DT Pin Tied to VCCI
        2. 8.4.2.2 Connecting a Programming Resistor between DT and GND Pins
  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 Dead Time Resistor and Capacitor
        3. 9.2.2.3 Select External Bootstrap Diode and Its Series Resistor
        4. 9.2.2.4 Gate Driver Output Resistor
        5. 9.2.2.5 Gate to Source Resistor Selection
        6. 9.2.2.6 Estimating Gate Driver Power Loss
        7. 9.2.2.7 Estimating Junction Temperature
        8. 9.2.2.8 Selecting VCCI, VDDA/B Capacitor
          1. 9.2.2.8.1 Selecting a VCCI Capacitor
          2. 9.2.2.8.2 Selecting a VDDA (Bootstrap) Capacitor
          3. 9.2.2.8.3 Select a VDDB Capacitor
        9. 9.2.2.9 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

8.3.4 Output Stage

The UCC2154x output stage features a pull-up structure which delivers the highest peak-source current when it is most needed: during the Miller plateau region of the power-switch turn on transition (when the power switch drain or collector voltage experiences dV/dt). The output stage pull-up structure features a P-channel MOSFET and an additional pull-up N-channel MOSFET in parallel. The function of the N-channel MOSFET is to provide a boost in the peak-sourcing current, enabling fast turn on. This is accomplished by briefly turning on the N-channel MOSFET during a narrow instant when the output is changing states from low to high. The on-resistance of this N-channel MOSFET (RNMOS) for UCC21540 is approximately 1.47-Ω when activated, and RNMOS is approximately 3.2-Ω for UCC21541.

The ROH parameter is a DC measurement and it is representative of the on-resistance of the P-channel device only. This is because the pull-up N-channel device is held in the off state in DC condition and is turned on only for a brief instant when the output is changing states from low to high. Therefore the effective resistance of the UCC2154x pull-up stage during this brief turn-on phase is much lower than what is represented by the ROH parameter.

The pull-down structure of the UCC2154x is composed of an N-channel MOSFET. The ROL parameter, which is also a DC measurement, is representative of the impedance of the pull-down state in the device. The output voltage swings between VDD and VSS for rail-to-rail operation.

To ensure robust and reliable operation of gate drivers, pay special attention to the minimum pulse width. The minimum pulse width shown in the electrical characteristics table describes the minimum input pulse that would be passed to the output in an unloaded driver. This is dictated by the deglitch filter present in the driver IC. An input ON or OFF pulse width longer than the maximum specification is needed to guarantee an output state change and avoid potential shoot-through. With a loaded driver, extra precaution must be taken to ensure robust operation of the system. During gate switching, if the output state changes before the driver completes each transition, a non-zero current switching event occurs. Combined with layout parasitics, non-zero current switching can cause internal rail overshoot and EOS damage of the gate driver. Thus, a minimum output width is needed for reliable system operation. This minimum output pulse width is dependent on several factors: gate capacitance, VDD supply voltage, gate resistance, and PCB layout parasitics. The minimum pulse width for robust operation might be magnitudes larger than the minimum pulse width shown in the electrical characteristics table. System-level study should be carried out to determine the minimum output pulse width required for each system.

UCC21540 UCC21540A UCC21541 UCC21542 Output Stage Figure 8-2 Output Stage