SLUSEM3B March   2022  – January 2023 UCC21737-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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  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
  7. 7 Parameter Measurement Information
    1. 7.1 Propagation Delay
      1. 7.1.1 Regular Turn-OFF
    2. 7.2 Input Deglitch Filter
    3. 7.3 Active Miller Clamp
      1. 7.3.1 External Active Miller Clamp
    4. 7.4 Undervoltage Lockout (UVLO)
      1. 7.4.1 VCC UVLO
      2. 7.4.2 VDD UVLO
      3. 7.4.3 VEE UVLO
    5. 7.5 Overcurrent (OC) Protection
      1. 7.5.1 OC Protection with Soft Turn-OFF
    6. 7.6 ASC Support
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Power Supply
      2. 8.3.2  Driver Stage
      3. 8.3.3  VCC, VDD, and VEE Undervoltage Lockout (UVLO)
      4. 8.3.4  Active Pulldown
      5. 8.3.5  Short Circuit Clamping
      6. 8.3.6  External Active Miller Clamp
      7. 8.3.7  Overcurrent and Short Circuit Protection
      8. 8.3.8  Soft Turn-off
      9. 8.3.9  Fault (FLT), Reset, and Enable (RST/EN)
      10. 8.3.10 ASC Support and APWM Monitor
    4. 8.4 Device Functional Modes
  9. 9 Applications 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 Input Filters for IN+, IN-, and RST/EN
        2. 9.2.2.2 PWM Interlock of IN+ and IN-
        3. 9.2.2.3 FLT, RDY, and RST/EN Pin Circuitry
        4. 9.2.2.4 RST/EN Pin Control
        5. 9.2.2.5 Turnon and Turnoff Gate Resistors
        6. 9.2.2.6 External Active Miller Clamp
        7. 9.2.2.7 Overcurrent and Short Circuit Protection
          1. 9.2.2.7.1 Protection Based on Power Modules with Integrated SenseFET
          2. 9.2.2.7.2 Protection Based on Desaturation Circuit
          3. 9.2.2.7.3 Protection Based on Shunt Resistor in Power Loop
        8. 9.2.2.8 Higher Output Current Using an External Current Buffer
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9.2.2.6 External Active Miller Clamp

The external active Miller clamp feature allows the gate driver to stay at the low status when the gate voltage is detected below VCLMPTH. When the other switch of the phase leg turns on, the dV/dt can cause a current through the parasitic Miller capacitance of the switch and sink in the gate driver. The sinking current causes a negative voltage drop on the turn-off gate resistance, and bumps up the gate voltage to cause a false turn on. The external active Miller clamp features allow flexibility of board layout and active Miller clamp pulldown strength. Limited by the board layout, if the driver cannot be placed close enough to the switch, an external active Miller clamp MOSFET can be placed close to the switch and the MOSFET can be chosen according to the peak current needed. Caution must be exercised when the driver is placed far from the power semiconductor. Since the device has high peak sink and source currents, the high dI/dt in the gate loop can cause a ground bounce on the board parasitics. The ground bounce can cause a positive voltage bump on the CLMPE pin during the turn-off transient, and results in the external active Miller clamp MOSFET to turn on shortly and add extra drive strength to the sink current. To reduce the ground bounce, a 2-Ω resistance is recommended to the gate of the external active clamp MOSFET.

When VOUTH is detected to be lower than VCLMPTH above VEE, the CLMPE pin outputs a 5-V voltage with respect to VEE, the external clamp FET is in linear region and the pulldown current is determined by the peak drain current, unless the on-resistance of the external clamp FET is large.

Equation 9. GUID-94C847B6-A8CB-4BB9-AF80-8041D36F1C91-low.gif

Where

  • ID_PK is the peak drain current of the external clamp FET
  • VDS is the drain-to-source voltage of the clamp FET when the CLMPE is activated
  • RDS_ON is the on-resistance of the external clamp FET

The total delay time of the active Miller clamp circuit from the gate voltage detection threshold VCLMPTH can be calculated as tDCLMPE+tCLMPER. tCLMPER depends on the parameter of the external active Miller clamp MOSFET. As long as the total delay time is longer than the dead time of high-side and low-side switches, the driver can effectively protect the switch from a false turn-on issue caused by the Miller effect.

GUID-0E304732-54F4-46D1-B734-D911465DA6F4-low.gifFigure 9-7 External Active Miller Clamp Configuration