ZHCSLU2B December   2021  – October 2023 LM63460-Q1

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Revision History
  6. 5 Device Comparison Table
  7. 6 Pin Configuration and Functions
    1. 6.1 Wettable Flanks
    2. 6.2 Pinout Design for Clearance and FMEA
  8. 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 Timing Characteristics
    7. 7.7 Systems Characteristics
    8. 7.8 Typical Characteristics
  9. 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 (VIN1, VIN2)
      2. 8.3.2  Output Voltage Setpoint (FB)
      3. 8.3.3  Precision Enable and Input Voltage UVLO (EN/SYNC)
      4. 8.3.4  Frequency Synchronization (EN/SYNC)
      5. 8.3.5  Clock Locking
      6. 8.3.6  Adjustable Switching Frequency (RT)
      7. 8.3.7  Power-Good Monitor (PGOOD)
      8. 8.3.8  Bias Supply Regulator (VCC, BIAS)
      9. 8.3.9  Bootstrap Voltage and UVLO (CBOOT)
      10. 8.3.10 Spread Spectrum
      11. 8.3.11 Soft Start and Recovery From Dropout
      12. 8.3.12 Overcurrent and Short-Circuit Protection
      13. 8.3.13 Thermal Shutdown
      14. 8.3.14 Input Supply Current
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Standby Mode
      3. 8.4.3 Active Mode
        1. 8.4.3.1 CCM Mode
        2. 8.4.3.2 AUTO Mode – Light-Load Operation
          1. 8.4.3.2.1 Diode Emulation
          2. 8.4.3.2.2 Frequency Foldback
        3. 8.4.3.3 FPWM Mode – Light-Load Operation
        4. 8.4.3.4 Minimum On-Time (High Input Voltage) Operation
        5. 8.4.3.5 Dropout
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Design 1 – Automotive Synchronous Buck Regulator at 2.1 MHz
        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  Setting the Output Voltage
          3. 9.2.1.2.3  Choosing the Switching Frequency
          4. 9.2.1.2.4  Inductor Selection
          5. 9.2.1.2.5  Output Capacitor Selection
          6. 9.2.1.2.6  Input Capacitor Selection
          7. 9.2.1.2.7  Bootstrap Capacitor
          8. 9.2.1.2.8  VCC Capacitor
          9. 9.2.1.2.9  BIAS Power Connection
          10. 9.2.1.2.10 Feedforward Network
          11. 9.2.1.2.11 Input Voltage UVLO
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Design 2 – Automotive Synchronous Buck Regulator at 400 kHz
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
        1. 9.4.1.1 Thermal Design and Layout
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 第三方产品免责声明
      2. 10.1.2 Development Support
        1. 10.1.2.1 Custom Design With WEBENCH® Tools
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 接收文档更新通知
    4. 10.4 支持资源
    5. 10.5 Trademarks
    6. 10.6 静电放电警告
    7. 10.7 术语表
  12. 11Mechanical, Packaging, and Orderable Information

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8.3.14 Input Supply Current

The converter is designed to have very low input supply current when regulating at light loads. This is achieved by powering much of the internal circuits from the output. The BIAS pin is the input to the LDO that powers the majority of the control circuits. By connecting BIAS to the regulator output, a small amount of current is drawn from the output. This current is reduced at the input by the ratio of VOUT / VIN. Equation 4 defines the current consumed by the operating (switching) buck converter at no load:

Equation 4. GUID-20211026-SS0I-Z7GR-2NBJ-QXSHNR6CS7GW-low.svg

where

  • IQ_VIN is the current into the VIN pins – see the Electrical Characteristics.
  • IEN is current into the EN/SYNC pin – see the Electrical Characteristics. Include this current if EN/SYNC is connected to VIN. Note that this current drops to a very low value if EN/SYNC connects to a voltage less than 5 V.
  • IDIV is the current consumption of the feedback divider used to set output voltage.
  • ηeff is the light-load efficiency when IQ_VIN is removed from the input current of the buck converter. ηeff = 0.8 is a conservative value that can be used under normal operating conditions.