ZHCSIM4H April   2009  – November 2014 LM25011 , LM25011-Q1

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
  3. 3 说明
    1.     典型应用
  4. 4 修订历史记录
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Handling Ratings: LM25011
    3. 6.3 Handling Ratings: LM25011-Q1
    4. 6.4 Recommended Operating Conditions
    5. 6.5 Thermal Information
    6. 6.6 Electrical Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Control Circuit Overview
      2. 7.3.2 On-Time Timer
      3. 7.3.3 Current Limit
      4. 7.3.4 Ripple Requirements
      5. 7.3.5 N-Channel Buck Switch and Driver
      6. 7.3.6 Soft-Start
      7. 7.3.7 Power Good Output (PGD)
      8. 7.3.8 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Function
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 LM25011 Example Circuit
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Custom Design with WEBENCH Tools
          2. 8.2.1.2.2 External Components
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Output Ripple Control
        1. 8.2.2.1 Option A: Lowest Cost Configuration
        2. 8.2.2.2 Option B: Intermediate VOUT Ripple Configuration
        3. 8.2.2.3 Option C: Minimum VOUT Ripple Configuration
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Power Dissipation
  11. 11器件和文档支持
    1. 11.1 使用 WEBENCH 工具创建定制设计
    2. 11.2 接收文档更新通知
    3. 11.3 相关链接
    4. 11.4 商标
    5. 11.5 静电放电警告
    6. 11.6 术语表
  12. 12机械、封装和可订购信息

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

8.2.2 Output Ripple Control

High frequency applications of the LM25011 or LM25011A are likely to require more ripple voltage than is internally generated across the RS resistor. Additional ripple can be supplied to the FB pin, in phase with the switching waveform at the SW pin, for proper operation. The required ripple can be supplied from ripple generated at VOUT, through the feedback resistors, as described in Option A: Lowest Cost Configuration. Option B: Intermediate VOUT Ripple Configuration and Option C: Minimum VOUT Ripple Configuration use one or two additional components to provide ripple at the FB pin with lower output ripple at VOUT.

The amount of additional ripple voltage needed at the FB pin is typically in the range of 30 mV to 150 mV. Higher switching frequencies or higher inductor values (less ripple current) require more external ripple voltage injected at the FB pin. Insufficient ripple voltage will result in frequency jitter. For a particular application, add only as much ripple as needed to stabilize the switching frequency over the required input voltage.