JAJSPL2 October   2024 TPSM82916

ADVANCE INFORMATION  

  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 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  Smart Config (S-CONF)
      2. 6.3.2  Device Enable (EN/SYNC)
      3. 6.3.3  Device Synchronization (EN/SYNC)
      4. 6.3.4  Spread Spectrum Modulation
      5. 6.3.5  Output Discharge
      6. 6.3.6  Undervoltage Lockout (UVLO)
      7. 6.3.7  Power-Good Output
      8. 6.3.8  Noise Reduction and Soft-Start Capacitor (NR/SS)
      9. 6.3.9  Current Limit and Short-Circuit Protection
      10. 6.3.10 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Fixed Frequency Pulse Width Modulation
      2. 6.4.2 Low Duty Cycle Operation
      3. 6.4.3 High Duty Cycle Operation (100% Duty Cycle)
      4. 6.4.4 Second Stage L-C Filter Compensation (Optional)
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Custom Design With WEBENCH® Tools
        2. 7.2.2.2 External Component Selection
          1. 7.2.2.2.1 Switching Frequency Selection
          2. 7.2.2.2.2 Output Capacitor Selection
          3. 7.2.2.2.3 Ferrite Bead Selection for Second L-C Filter
          4. 7.2.2.2.4 Input Capacitor Selection
          5. 7.2.2.2.5 Setting the Output Voltage
          6. 7.2.2.2.6 NR/SS Capacitor Selection
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 サード・パーティ製品に関する免責事項
      2. 8.1.2 Development Support
        1. 8.1.2.1 Custom Design With WEBENCH® Tools
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 ドキュメントの更新通知を受け取る方法
    4. 8.4 サポート・リソース
    5. 8.5 Trademarks
    6. 8.6 静電気放電に関する注意事項
    7. 8.7 用語集
  10. 9 Revision History
  11. 10Mechanical, 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）
  • VCE|16
サーマルパッド・メカニカル・データ
発注情報
7.2.2.2.1 Switching Frequency Selection

The switching frequency can be chosen to optimize efficiency (lower) or ripple noise (higher). Using the higher 1.4MHz or 2.2MHz setting increases the gain of the feedback loop and can result in lower output noise. However, additional considerations for minimum on-time and duty cycle must also be considered. First, calculate the duty cycle using Equation 3. Higher efficiency results in a shorter on-time, so a conservative approach is to use a higher efficiency than expected in the application.

Equation 3. D = V O U T V I N   ×   η

where:

  • η = estimated efficiency (use the value from the efficiency curves or 0.9 as an conservative assumption)

Then, calculate the on-time with 1MHz, 1.4MHz, and 2.2MHz using Equation 4. The on-time must always remain above the minimum on-time of 70ns. Use the maximum input voltage and maximum efficiency to determine the minimum duty cycle, Dmin. Use the maximum switching frequency for fSW.

Equation 4. T O N = D m i n f S W _ m i n

then

  • If tON_min minimum < 70ns with 2.2MHz, use 1.4MHz.
  • If tON_min minimum < 70ns with 1.4MHz, use 1MHz
  • If tON_min minimum < 70ns with 1MHz, reduce the maximum input voltage.
  • If tON_min minimum ≥ 70ns, use a lower frequency for highest efficiency, or the highest frequency for the lowest noise and ripple.