ZHCSNC7 December   2021 LM25148

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 说明（续）
  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 接收文档更新通知
    4. 12.4 支持资源
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 术语表
  13. 13Mechanical, Packaging, and Orderable Information

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9.2.1 Design 1 – High Efficiency 2.1-MHz Synchronous Buck Regulator

Figure 9-4 shows the schematic diagram of a single-output synchronous buck regulator with an output voltage of 5 V and a rated load current of 8 A. In this example, the target half-load and full-load efficiencies are 93.5% and 92.5%, respectively, based on a nominal input voltage of 12 V that ranges from 5.5 V to 36 V. The switching frequency is set at 2.1 MHz by resistor RRT. The 5-V output is connected to VCCX to reduce IC bias power dissipation and improve efficiency. An output voltage of 3.3 V is also feasible simply by connecting FB to VDDA.

Figure 9-4 Application Circuit 1 With LM25148 Buck Regulator at 2.1 MHz
Note:

This and subsequent design examples are provided herein to showcase the LM25148 controller in several different applications. Depending on the source impedance of the input supply bus, an electrolytic capacitor can be required at the input to ensure stability, particularly at low input voltage and high output current operating conditions. See Section 10 for more details.