JAJSL79 December   2021 LM25148

PRODUCTION DATA  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
  4. 4 Revision History
  5. 5 概要 (続き)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Input Voltage Range (VIN)
      2. 8.3.2  High-Voltage Bias Supply Regulator (VCC, VCCX, VDDA)
      3. 8.3.3  Precision Enable (EN)
      4. 8.3.4  Power-Good Monitor (PG)
      5. 8.3.5  Switching Frequency (RT)
      6. 8.3.6  Dual Random Spread Spectrum (DRSS)
      7. 8.3.7  Soft Start
      8. 8.3.8  Output Voltage Setpoint (FB)
      9. 8.3.9  Minimum Controllable On Time
      10. 8.3.10 Error Amplifier and PWM Comparator (FB, EXTCOMP)
      11. 8.3.11 Slope Compensation
      12. 8.3.12 Inductor Current Sense (ISNS+, VOUT)
        1. 8.3.12.1 Shunt Current Sensing
        2. 8.3.12.2 Inductor DCR Current Sensing
      13. 8.3.13 Hiccup Mode Current Limiting
      14. 8.3.14 High-Side and Low-Side Gate Drivers (HO, LO)
      15. 8.3.15 Output Configurations (CNFG)
      16. 8.3.16 Single-Output Dual-Phase Operation
    4. 8.4 Device Functional Modes
      1. 8.4.1 Sleep Mode
      2. 8.4.2 Pulse Frequency Modulation and Synchronization (PFM/SYNC)
      3. 8.4.3 Thermal Shutdown
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Power Train Components
        1. 9.1.1.1 Buck Inductor
        2. 9.1.1.2 Output Capacitors
        3. 9.1.1.3 Input Capacitors
        4. 9.1.1.4 Power MOSFETs
        5. 9.1.1.5 EMI Filter
      2. 9.1.2 Error Amplifier and Compensation
    2. 9.2 Typical Applications
      1. 9.2.1 Design 1 – High Efficiency 2.1-MHz Synchronous Buck Regulator
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Custom Design With WEBENCH® Tools
          2. 9.2.1.2.2 Custom Design With Excel Quickstart Tool
          3. 9.2.1.2.3 Buck Inductor
          4. 9.2.1.2.4 Current-Sense Resistance
          5. 9.2.1.2.5 Output Capacitors
          6. 9.2.1.2.6 Input Capacitors
          7. 9.2.1.2.7 Frequency Set Resistor
          8. 9.2.1.2.8 Feedback Resistors
          9. 9.2.1.2.9 Compensation Components
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Design 2 – High Efficiency 440-kHz Synchronous Buck Regulator
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
      3. 9.2.3 Design 3 – Dual-Phase 400-kHz 20-A Synchronous Buck Regulator
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
        3. 9.2.3.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Power Stage Layout
      2. 11.1.2 Gate-Drive Layout
      3. 11.1.3 PWM Controller Layout
      4. 11.1.4 Thermal Design and Layout
      5. 11.1.5 Ground Plane Design
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
        1. 12.1.1.1 Custom Design With WEBENCH® Tools
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
        1. 12.2.1.1 PCB Layout Resources
        2. 12.2.1.2 Thermal Design Resources
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 サポート・リソース
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 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
9.2.1.2.3 Buck Inductor
  1. Use Equation 30 to calculate the required buck inductance based on a 30% inductor ripple current at nominal input voltages.
    Equation 30. GUID-9C395139-5313-48D0-91A5-37980286BF21-low.gif
  2. Select a standard inductor value of 0.56 µH or use a 0.68 µH to account for effective inductance derating with current of molded inductors. Use Equation 31 to calculate the peak inductor currents at maximum steady-state input voltage. Subharmonic oscillation occurs with a duty cycle greater than 50% for peak current-mode control. For design simplification, the LM25148 has an internal slope compensation ramp proportional to the switching frequency that is added to the current sense signal to damp any tendency toward subharmonic oscillation.
    Equation 31. GUID-E14F0405-678D-4244-ACC1-F3AD4222B5F6-low.gif
  3. Based on Equation 8, use Equation 32 to cross-check the inductance to set a slope compensation close to the ideal one times the inductor current downslope.
    Equation 32. GUID-D4BD7F1C-DD51-4679-88F7-DDFE63C520A5-low.gif