JAJSFB3 April   2018 LM25119Q

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  High Voltage Start-Up Regulator
      2. 8.3.2  UVLO
      3. 8.3.3  Enable 2
      4. 8.3.4  Oscillator and Sync Capability
      5. 8.3.5  Error Amplifiers and PWM Comparators
      6. 8.3.6  Ramp Generator
      7. 8.3.7  Current Limit
      8. 8.3.8  Hiccup Mode Current Limiting
      9. 8.3.9  Soft Start
      10. 8.3.10 HO and LO Output Drivers
      11. 8.3.11 Maximum Duty Cycle
      12. 8.3.12 Thermal Protection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Diode Emulation
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Miscellaneous Functions
      2. 9.1.2 Interleaved Two-Phase Operation
      3. 9.1.3 Interleaved 4-Phase Operation
    2. 9.2 Typical Applications
      1. 9.2.1 Dual-output Design Example
        1. 9.2.1.1 Design Requirements
          1. 9.2.1.1.1 External Components
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1  Timing Resistor
          2. 9.2.1.2.2  Output Inductor
          3. 9.2.1.2.3  Current Sense Resistor
          4. 9.2.1.2.4  Ramp Resistor and Ramp Capacitor
          5. 9.2.1.2.5  Output Capacitors
          6. 9.2.1.2.6  Input Capacitors
          7. 9.2.1.2.7  VCC Capacitor
          8. 9.2.1.2.8  Bootstrap Capacitor
          9. 9.2.1.2.9  Soft Start Capacitor
          10. 9.2.1.2.10 Restart Capacitor
          11. 9.2.1.2.11 Output Voltage Divider
          12. 9.2.1.2.12 UVLO Divider
          13. 9.2.1.2.13 MOSFET Selection
          14. 9.2.1.2.14 MOSFET Snubber
          15. 9.2.1.2.15 Error Amplifier Compensation
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Two-Phase Design Example
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Switching Jitter Root Causes and Solutions
    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 コミュニティ・リソース
    2. 12.2 商標
    3. 12.3 静電気放電に関する注意事項
    4. 12.4 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

11.1.1 Switching Jitter Root Causes and Solutions

  • Noise coupling of the high frequency switching between two channels through the input power rail
    • Maintain the high current path as short as possible
    • Choose a FET with minimum lead inductance
    • Place local bypass capacitors (CIN1, CIN2) as close as possible to the high-side FETs to isolate one channel from the high frequency noise of the other channel
    • Slow down the SW switching speed by increasing gate resistors R29 and R30
    • Minimize the effective ESR or ESL of the input capacitor by paralleling input capacitors
  • High frequency AC noise on FB, CS, CSG and COMP
    • Use the star ground PCB layout technique and minimize the length of the high current path
    • Place the signal traces away from the SW, HO, HB traces and the inductor
    • Add an R-C filter between the CS and CSG pins
    • Place CS filter capacitor (C30, C31) next to the LM25119Q and on the same PCB layer as the LM25119
  • Ground offset at the switching frequency
    • Use the star ground PCB layout technique and minimize the length between the grounds of CIN1 and CIN2