ZHCSCY3E October   2014  – October 2018 LM5160 , LM5160A

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
  3. 3 说明
    1.     Device Images
      1.      典型同步降压应用电路
      2.      典型 Fly-Buck 应用电路
  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 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Switching 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
      2. 7.3.2  VCC Regulator
      3. 7.3.3  Regulation Comparator
      4. 7.3.4  Soft Start
      5. 7.3.5  Error Amplifier
      6. 7.3.6  On-Time Generator
      7. 7.3.7  Current Limit
      8. 7.3.8  N-Channel Buck Switch and Driver
      9. 7.3.9  Synchronous Rectifier
      10. 7.3.10 Enable / Undervoltage Lockout (EN/UVLO)
      11. 7.3.11 Thermal Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Forced Pulse Width Modulation (FPWM) Mode
      2. 7.4.2 Undervoltage Detector
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Ripple Configuration
    2. 8.2 Typical Applications
      1. 8.2.1 LM5160 Synchronous Buck (10-V to 60-V Input, 5-V Output, 1.5-A Load)
        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  Feedback Resistor Divider - RFB1, RFB2
          3. 8.2.1.2.3  Switching Frequency - RON
          4. 8.2.1.2.4  Inductor - L
          5. 8.2.1.2.5  Output Capacitor - COUT
          6. 8.2.1.2.6  Series Ripple Resistor - RESR
          7. 8.2.1.2.7  VCC and Bootstrap Capacitors - CVCC, CBST
          8. 8.2.1.2.8  Input Capacitor - CIN
          9. 8.2.1.2.9  Soft-Start Capacitor - CSS
          10. 8.2.1.2.10 EN/UVLO Resistors - RUV1, RUV2
        3. 8.2.1.3 Application Curves
      2. 8.2.2 LM5160 Isolated Fly-Buck (18-V to 32-V Input, 12-V, 4.5-W Isolated Output)
        1. 8.2.2.1 LM5160 Fly-Buck Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Selection of VOUT1 and Turns Ratio
          2. 8.2.2.2.2 Secondary Rectifier Diode
          3. 8.2.2.2.3 External Ripple Circuit
          4. 8.2.2.2.4 Output Capacitor - COUT2
        3. 8.2.2.3 Application Curves
      3. 8.2.3 LM5160A Isolated Fly-Buck (18-V to 32-V Input, 12-V, 4.5-W Isolated Output)
    3. 8.3 Do's and Don'ts
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11器件和文档支持
    1. 11.1 器件支持
      1. 11.1.1 第三方产品免责声明
      2. 11.1.2 开发支持
        1. 11.1.2.1 使用 WEBENCH® 工具创建定制设计
    2. 11.2 文档支持
      1. 11.2.1 相关文档
    3. 11.3 相关链接
    4. 11.4 接收文档更新通知
    5. 11.5 社区资源
    6. 11.6 商标
    7. 11.7 静电放电警告
    8. 11.8 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

8.2.1.2.4 Inductor - L

Select the inductor to limit the inductor ripple current between 20 and 40 percent of the maximum load current. Calculate the minimum value of the inductance required in this application from Equation 13.

Equation 13. LM5160 LM5160A eq10_snvsa03.gif

Based on Equation 13, determine the minimum value of the inductance as 26 µH for VIN = 65 V (maximum) and inductor ripple current equal to 40 percent of the maximum load current. Allowing some margin for inductance variation with current, select a higher standard value of L1 (L) = 47 µH for this design.

The peak inductor current at maximum load must be smaller than the minimum current limit threshold of the high-side FET, as given inElectrical Characteristics table. Determine the inductor ripple current at any input voltage using Equation 14.

Equation 14. LM5160 LM5160A eq11_snvsa03.gif

Calculate the peak-to-peak inductor ripple current as 180 mA and 332 mA at the minimum and maximum input voltages, respectively. Determine the maximum peak inductor current in the buck FET using Equation 15.

Equation 15. LM5160 LM5160A eq12_snvsa03.gif

In this design with an output current of 1.5 A, the maximum peak inductor current is calculated to be approximately 1.67 A, which is less than the high-side FET minimum current limit threshold.

The saturation current of the inductor must also be carefully considered. The peak value of the inductor current is bound by the high-side FET current limit during overload or short circuit conditions. Based on the high-side FET current limit specification in Electrical Characteristics, select an inductor with saturation current rating above 2.875 A.