SNVSBU4E June   2022  – August 2024 LM5177

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 Handling Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Parameter Measurement Information
    1. 6.1 Gate Driver Rise Time and Fall Time
    2. 6.2 Gate Driver Dead (Transition) Time
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Power-On Reset (POR System)
      2. 7.3.2  Buck-Boost Control Scheme
        1. 7.3.2.1 Boost Mode
        2. 7.3.2.2 Buck Mode
        3. 7.3.2.3 Buck-Boost Mode
      3. 7.3.3  Power Save Mode
      4. 7.3.4  Supply Voltage Selection – VMAX Switch
      5. 7.3.5  Enable and Undervoltage Lockout
      6. 7.3.6  Oscillator Frequency Selection
      7. 7.3.7  Frequency Synchronization
      8. 7.3.8  Voltage Regulation Loop
      9. 7.3.9  Output Voltage Tracking
      10. 7.3.10 Slope Compensation
      11. 7.3.11 Configurable Soft Start
      12. 7.3.12 Peak Current Sensor
      13. 7.3.13 Current Monitoring and Current Limit Control Loop
      14. 7.3.14 Short Circuit - Hiccup Protection
      15. 7.3.15 nFLT Pin and Protections
      16. 7.3.16 Device Configuration Pin
      17. 7.3.17 Dual Random Spread Spectrum – DRSS
      18. 7.3.18 Gate Driver
    4. 7.4 Device Functional Modes
  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  Frequency
        3. 8.2.2.3  Feedback Divider
        4. 8.2.2.4  Inductor and Current Sense Resistor Selection
        5. 8.2.2.5  Slope Compensation
        6. 8.2.2.6  Output Capacitor
        7. 8.2.2.7  Input Capacitor
        8. 8.2.2.8  UVLO Divider
        9. 8.2.2.9  Soft-Start Capacitor
        10. 8.2.2.10 MOSFETs QH1 and QL1
        11. 8.2.2.11 MOSFETs QH2 and QL2
        12. 8.2.2.12 Frequency Compensation
        13. 8.2.2.13 External Component Selection
      3. 8.2.3 Application Curves
    3. 8.3 System Examples
      1. 8.3.1 Bi-Directional Power Backup
      2. 8.3.2 Parallel (Multiphase) Operation
  10. 9 Power Supply Recommendations
  11. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Power Stage Layout
      2. 10.1.2 Gate Driver Layout
      3. 10.1.3 Controller Layout
    2. 10.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Development Support
        1. 11.1.2.1 Custom Design with WEBENCH Tools
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  13. 12Revision History
  14. 13Mechanical, Packaging, and Orderable Information

7.3.2.2 Buck Mode

In buck mode operation, the converter starts a buck magnetization cycle (state II) with the internal clock signal. When the inductor reaches its peak current, the converter proceeds to the buck demagnetization state III. With the next clock signal, the converter changes back to a buck magnetization cycle and starts a new switching cycle with sampling the peak current. As long as the duty cycle does not reach the minimum off time, the current control remains in buck operating mode.


LM5177 Inductor Current in Continuous Current Buck Operation

Figure 7-3 Inductor Current in Continuous Current Buck Operation