JAJSGD5E October   2014  – October 2018 LM5160 , LM5160A

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      代表的な同期整流降圧アプリケーション回路
      2.      代表的なFly-Buckアプリケーション回路
  4. 4 改訂履歴
  5. 5 概要（続き）
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Switching Characteristics
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Control Circuit
      2. 8.3.2  VCC Regulator
      3. 8.3.3  Regulation Comparator
      4. 8.3.4  Soft Start
      5. 8.3.5  Error Amplifier
      6. 8.3.6  On-Time Generator
      7. 8.3.7  Current Limit
      8. 8.3.8  N-Channel Buck Switch and Driver
      9. 8.3.9  Synchronous Rectifier
      10. 8.3.10 Enable / Undervoltage Lockout (EN/UVLO)
      11. 8.3.11 Thermal Protection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Forced Pulse Width Modulation (FPWM) Mode
      2. 8.4.2 Undervoltage Detector
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Ripple Configuration
    2. 9.2 Typical Applications
      1. 9.2.1 LM5160 Synchronous Buck (10-V to 60-V Input, 5-V Output, 1.5-A Load)
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1  Custom Design With WEBENCH® Tools
          2. 9.2.1.2.2  Feedback Resistor Divider - RFB1, RFB2
          3. 9.2.1.2.3  Switching Frequency - RON
          4. 9.2.1.2.4  Inductor - L
          5. 9.2.1.2.5  Output Capacitor - COUT
          6. 9.2.1.2.6  Series Ripple Resistor - RESR
          7. 9.2.1.2.7  VCC and Bootstrap Capacitors - CVCC, CBST
          8. 9.2.1.2.8  Input Capacitor - CIN
          9. 9.2.1.2.9  Soft-Start Capacitor - CSS
          10. 9.2.1.2.10 EN/UVLO Resistors - RUV1, RUV2
        3. 9.2.1.3 Application Curves
      2. 9.2.2 LM5160 Isolated Fly-Buck (18-V to 32-V Input, 12-V, 4.5-W Isolated Output)
        1. 9.2.2.1 LM5160 Fly-Buck Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Selection of VOUT1 and Turns Ratio
          2. 9.2.2.2.2 Secondary Rectifier Diode
          3. 9.2.2.2.3 External Ripple Circuit
          4. 9.2.2.2.4 Output Capacitor - COUT2
        3. 9.2.2.3 Application Curves
      3. 9.2.3 LM5160A Isolated Fly-Buck (18-V to 32-V Input, 12-V, 4.5-W Isolated Output)
    3. 9.3 Do's and Don'ts
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12デバイスおよびドキュメントのサポート
    1. 12.1 デバイス・サポート
      1. 12.1.1 デベロッパー・ネットワークの製品に関する免責事項
      2. 12.1.2 開発サポート
        1. 12.1.2.1 WEBENCH®ツールによるカスタム設計
    2. 12.2 ドキュメントのサポート
      1. 12.2.1 関連資料
    3. 12.3 関連リンク
    4. 12.4 ドキュメントの更新通知を受け取る方法
    5. 12.5 コミュニティ・リソース
    6. 12.6 商標
    7. 12.7 静電気放電に関する注意事項
    8. 12.8 Glossary
  13. 13メカニカル、パッケージ、および注文情報

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

8.4.1 Forced Pulse Width Modulation (FPWM) Mode

The Synchronous Rectifier section gives a brief introduction to the LM5160 diode emulation feature. The FPWM pin allows the power supply designer to select either CCM or DCM operation at light loads. When FPWM is connected to ground or left floating (FPWM = 0), a pulse-skipping mode and a zero-cross current detector circuit are enabled. The zero-cross detector turns off the low-side FET when the inductor current falls to zero (IZX, see Electrical Characteristics). This feature allows the LM5160 regulator to operate in DCM mode at light loads. In the DCM state, the switching frequency decreases with lighter loads.

If FPWM is pulled high (FPWM connected to VCC), the LM5160 operates in CCM even at light loads. This option allows the synchronous rectifier FET to conduct until the start of the next high-side switch cycle. The inductor current drops to zero and then reverse direction (negative direction through inductor), passing from drain to source of the low-side FET. The current flows continuously until the FB comparator initiates another high-side switch on-time. CCM operation reduces efficiency at light load but improves the transient response to step load changes and provides nearly constant switching frequency.

Table 1. FPWM Pin Mode Summary

FPWM PIN CONNECTION LOGIC STAGE DESCRIPTION
GND or Floating (High Z) 0 The FPWM pin is grounded or left floating. DCM enabled at light loads.
VCC 1 The FPWM pin is connected to VCC. The LM5160 then operates in CCM mode at light loads.