JAJSEW6B February   2018  – February 2024 UCC21222

PRODUCTION DATA  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  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  Power Ratings
    6. 5.6  Insulation Specifications
    7. 5.7  Safety-Related Certifications
    8. 5.8  Safety-Limiting Values
    9. 5.9  Electrical Characteristics
    10. 5.10 Switching Characteristics
    11. 5.11 Thermal Derating Curves
    12. 5.12 Typical Characteristics
  7. 6 Parameter Measurement Information
    1. 6.1 Minimum Pulses
    2. 6.2 Propagation Delay and Pulse Width Distortion
    3. 6.3 Rising and Falling Time
    4. 6.4 Input and Disable Response Time
    5. 6.5 Programmable Dead Time
    6. 6.6 Power-Up UVLO Delay to OUTPUT
    7. 6.7 CMTI Testing
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 VDD, VCCI, and Undervoltage Lock Out (UVLO)
      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 Diode Structure in the UCC21222
    4. 7.4 Device Functional Modes
      1. 7.4.1 Disable Pin
      2. 7.4.2 Programmable Dead Time (DT) Pin
        1. 7.4.2.1 DT Pin Tied to VCCI or DT Pin Left Open
        2. 7.4.2.2 Connecting a Programming Resistor between DT and GND Pins
  9. 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 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Designing INA/INB Input Filter
        3. 8.2.2.3 Select Dead Time Resistor and Capacitor
        4. 8.2.2.4 Select External Bootstrap Diode and its Series Resistor
        5. 8.2.2.5 Gate Driver Output Resistor
        6. 8.2.2.6 Estimating Gate Driver Power Loss
        7. 8.2.2.7 Estimating Junction Temperature
        8. 8.2.2.8 Selecting VCCI, VDDA/B Capacitor
          1. 8.2.2.8.1 Selecting a VCCI Capacitor
          2. 8.2.2.8.2 Selecting a VDDA (Bootstrap) Capacitor
          3. 8.2.2.8.3 Select a VDDB Capacitor
        9. 8.2.2.9 Application Circuits with Output Stage Negative Bias
      3. 8.2.3 Application Curves
  10. 9 Power Supply Recommendations
  11. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Component Placement Considerations
      2. 10.1.2 Grounding Considerations
      3. 10.1.3 High-Voltage Considerations
      4. 10.1.4 Thermal Considerations
    2. 10.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 サード・パーティ製品に関する免責事項
      2. 11.1.2 Development Support
        1. 11.1.2.1 Custom Design With WEBENCH® Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 ドキュメントの更新通知を受け取る方法
    4. 11.4 サポート・リソース
    5. 11.5 Trademarks
    6. 11.6 静電気放電に関する注意事項
    7. 11.7 用語集
  13. 12Revision History
  14. 13Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

8.2.2.5 Gate Driver Output Resistor

The external gate driver resistors, RON/ROFF, are used to:

  1. Limit ringing caused by parasitic inductances/capacitances.
  2. Limit ringing caused by high voltage/current switching dv/dt, di/dt, and body-diode reverse recovery.
  3. Fine-tune gate drive strength; that is, peak sink and source current to optimize the switching loss.
  4. Reduce electromagnetic interference (EMI).

As mentioned in Section 7.3.4, the UCC21222 has a pullup structure with a P-channel MOSFET and an additional pull-up N-channel MOSFET in parallel. The combined peak source current is 4 A. Therefore, the peak source current can be predicted with:

Equation 3. GUID-9FED7E70-004B-4531-A121-5E8A4D1E4329-low.gif
Equation 4. GUID-04030A45-E0E7-4BC1-B23C-3E528B00A7A7-low.gif

where

  • RON: External turn-on resistance.
  • RGFET_INT: Power transistor internal gate resistance, found in the power transistor data sheet.
  • IO+ = Peak source current – The minimum value between 4 A, the gate driver peak source current, and the calculated value based on the gate drive loop resistance.

In this example:

Equation 5. GUID-410E7795-9979-4680-9EFC-F5516FA5115B-low.gif
Equation 6. GUID-555A71C5-B963-49E0-A864-D4F0C994A2AC-low.gif

Therefore, the high-side and low-side peak source current is 2.3 A and 2.5 A respectively. Similarly, the peak sink current can be calculated with:

Equation 7. GUID-FDD15AB3-D58A-44C9-8330-88A710630492-low.gif
Equation 8. GUID-94B55CB8-9840-4B49-97D5-C52E49B0CD77-low.gif

where

  • ROFF: External turn-off resistance, ROFF=0 in this example;
  • VGDF: The anti-parallel diode forward voltage drop which is in series with ROFF. The diode in this example is an MSS1P4.
  • IO-: Peak sink current – the minimum value between 6 A, the gate driver peak sink current, and the calculated value based on the gate drive loop resistance.

In this example,

Equation 9. GUID-36513D86-250E-4E5D-A34F-AEF1E87FD529-low.gif
Equation 10. GUID-3D1CA09E-2CDE-46E8-9277-BDE62F5F080C-low.gif

Therefore, the high-side and low-side peak sink current is 5.0 A and 5.4 A, respectively.

Importantly, the estimated peak current is also influenced by PCB layout and load capacitance. Parasitic inductance in the gate driver loop can slow down the peak gate drive current and introduce overshoot and undershoot. Therefore, it is strongly recommended that the gate driver loop should be minimized. On the other hand, the peak source/sink current is dominated by loop parasitics when the load capacitance (CISS) of the power transistor is very small (typically less than 1 nF), because the rising and falling time is too small and close to the parasitic ringing period.