ZHCSKD6 October   2019 LM5163

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
  3. 3 说明
    1.     Device Images
      1.      典型应用
      2.      典型应用效率，VOUT = 12V
  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 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 Architecture
      2. 7.3.2  Internal VCC Regulator and Bootstrap Capacitor
      3. 7.3.3  Regulation Comparator
      4. 7.3.4  Internal Soft Start
      5. 7.3.5  On-Time Generator
      6. 7.3.6  Current Limit
      7. 7.3.7  N-Channel Buck Switch and Driver
      8. 7.3.8  Synchronous Rectifier
      9. 7.3.9  Enable/Undervoltage Lockout (EN/UVLO)
      10. 7.3.10 Power Good (PGOOD)
      11. 7.3.11 Thermal Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Active Mode
      3. 7.4.3 Sleep Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Switching Frequency (RRON)
        3. 8.2.2.3 Buck Inductor (LO)
        4. 8.2.2.4 Output Capacitor (COUT)
        5. 8.2.2.5 Input Capacitor (CIN)
        6. 8.2.2.6 Type 3 Ripple Network
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Compact PCB Layout for EMI Reduction
      2. 10.1.2 Feedback Resistors
    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 相关文档
    3. 11.3 接收文档更新通知
    4. 11.4 支持资源
    5. 11.5 商标
    6. 11.6 静电放电警告
    7. 11.7 Glossary
  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

8.2.2.6 Type 3 Ripple Network

A Type 3 ripple generation network uses an RC filter consisting of RA and CA across SW and VOUT to generate a triangular ramp that is in phase with the inductor current. This triangular ramp is then AC-coupled into the feedback node using capacitor CB as shown in Figure 12. Type 3 ripple injection is suited for applications where low output voltage ripple is crucial.

Use Equation 24 and Equation 25 to calculate RA and CA to provide the required ripple amplitude at the FB pin.

Equation 24. LM5163 q_Ca_nvsb51.gif

For the feedback resistor values given in Figure 12, Equation 24 dictates a minimum CA of 742 pF. In this design, a 3300 pF capacitance is chosen. This is done to keep RA within practical limits between 100 kΩ and 1 MΩ when using Equation 25.

Equation 25. LM5163 q_RaCa_nvsb51.gif

Based on CA set at 3.3 nF, RA is calculated to be 226 kΩ to provide a 20-mV ripple voltage at FB. The general recommendation for a Type 3 network is to calculate RA and CA to get 20 mV of ripple at typical operating conditions, while ensuring a 12-mV minimum ripple voltage on FB at minimum VIN.

While the amplitude of the generated ripple does not affect the output voltage ripple, it impacts the output regulation as it reflects as a DC error of approximately half the amplitude of the generated ripple. For example, a converter circuit with Type 3 network that generates a 40-mV ripple voltage at the feedback node has approximately 10-mV worse load regulation scaled up through the FB divider to VOUT than the same circuit that generates a 20-mV ripple at FB. Use Equation 26 to calculate the coupling capacitance CB.

Equation 26. LM5163 q_Cb_nvsb51.gif

where

  • tTR-settling is the desired load transient response settling time

CB calculates to 56 pF based on a 75-µs settling time. This value avoids excessive coupling capacitor discharge by the feedback resistors during sleep intervals when operating at light loads. To avoid capacitance fall-off with DC bias, use a C0G or NP0 dielectric capacitor for CB.