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

7.3.9 Synchronous Rectifier

The LM5160 provides an internal low-side synchronous rectifier N-channel FET. This low-side FET provides a low resistance path for the inductor current when the high-side FET is turned off.

With the FPWM pin connected to ground or left floating, the LM5160 synchronous rectifier operates in diode emulation mode. Diode emulation enables the pulse-skipping during light load conditions. This leads to a reduction in the average switching frequency at light loads. Switching losses and FET gate driver losses, both of which are proportional to switching frequency, are significantly reduced and efficiency is improved. This pulse-skipping mode also reduces the circulating inductor currents and losses associated with a continuous conduction mode (CCM).

When FPWM is pulled high, diode emulation is disabled. The inductor current can flow in either direction through the low-side FET, resulting in CCM operation with nearly constant switching frequency. A negative sink current limit circuit limits the current that can flow into SW and through the low-side FET to ground. In a buck regulator application, large negative current typically only flows from VOUT to SW if VOUT is lifted above the output regulation setpoint.