ZHCSTL8F April   2007  – November 2023 LM25116

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  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 Switching Characteristics
    7. 5.7 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 High-Voltage Start-Up Regulator
      2. 6.3.2 Enable
      3. 6.3.3 UVLO
      4. 6.3.4 Oscillator and Sync Capability
      5. 6.3.5 Error Amplifier and PWM Comparator
      6. 6.3.6 Ramp Generator
      7. 6.3.7 Current Limit
      8. 6.3.8 HO Output
      9. 6.3.9 Thermal Protection
    4. 6.4 Device Functional Modes
      1. 6.4.1 Soft Start and Diode Emulation
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1  Timing Resistor
        2. 7.2.2.2  Output Inductor
        3. 7.2.2.3  Current Sense Resistor
        4. 7.2.2.4  Ramp Capacitor
        5. 7.2.2.5  Output Capacitors
        6. 7.2.2.6  Input Capacitors
        7. 7.2.2.7  VCC Capacitor
        8. 7.2.2.8  Bootstrap Capacitor
        9. 7.2.2.9  Soft Start Capacitor
        10. 7.2.2.10 Output Voltage Divider
        11. 7.2.2.11 UVLO Divider
        12. 7.2.2.12 MOSFETs
        13. 7.2.2.13 MOSFET Snubber
        14. 7.2.2.14 Error Amplifier Compensation
        15. 7.2.2.15 Comprehensive Equations
          1. 7.2.2.15.1 Current Sense Resistor and Ramp Capacitor
          2. 7.2.2.15.2 Modulator Transfer Function
          3. 7.2.2.15.3 Error Amplifier Transfer Function
      3. 7.2.3 Application Curves
    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 接收文档更新通知
    2. 8.2 支持资源
    3. 8.3 Trademarks
    4. 8.4 静电放电警告
    5. 8.5 术语表
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

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6.3.2 Enable

The LM25116 contains an enable function allowing a very low input current shutdown. If the enable pin is pulled below 0.5 V, the regulator enters shutdown, drawing less than 10 µA from the VIN pin. Raising the EN input above 3.3 V returns the regulator to normal operation. The maximum EN transition time for proper operation is one switching period. For example, the enable rise time must be less than 4 µs for 250-kHz operation.

A 1-MΩ pullup resistor to VIN can be used to interface with an open collector control signal. At low input voltage the pullup resistor may be reduced to 100 kΩ to speed up the EN transition time. The EN pin can be tied directly to VIN if this function is not required. It must not be left floating. If low-power shutdown is not required, the UVLO pin must be used as an on/off control.

GUID-A910F32E-ABB4-40E8-9F7E-BE4B06B1A58F-low.gifFigure 6-3 Enable Circuit
GUID-3272EE84-50C0-4636-8FEB-1B1604180C64-low.pngFigure 6-4 EN Bias Current vs Voltage