JAJSDZ5 October   2017 LM2623-Q1

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
  4. 4 改訂履歴
  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 Gated Oscillator Control Scheme
      2. 7.3.2 Cycle-To-Cycle PFM
      3. 7.3.3 Shutdown
      4. 7.3.4 Internal Current Limit and Thermal Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Pulse Frequency Modulation (PFM)
      2. 7.4.2 Low Voltage Start-Up
  8. 8 Applications 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 Non-Linear Effect
        2. 8.2.2.2 Choosing the Correct C3 Capacitor
        3. 8.2.2.3 Setting the Output Voltage
        4. 8.2.2.4 VDD Supply
        5. 8.2.2.5 Setting the Switching Frequency
        6. 8.2.2.6 Output Diode Selection
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Boost Output Capacitor Placement
      2. 10.1.2 Schottky Diode Placement
      3. 10.1.3 Boost Input / VDD Capacitor Placement
    2. 10.2 Layout Example
    3. 10.3 WSON Package Devices
  11. 11デバイスおよびドキュメントのサポート
    1. 11.1 デバイス・サポート
      1. 11.1.1 デベロッパー・ネットワークの製品に関する免責事項
    2. 11.2 ドキュメントのサポート
      1. 11.2.1 関連資料
    3. 11.3 ドキュメントの更新通知を受け取る方法
    4. 11.4 コミュニティ・リソース
    5. 11.5 商標
    6. 11.6 静電気放電に関する注意事項
    7. 11.7 Glossary
  12. 12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

8.2.2.2 Choosing the Correct C3 Capacitor

The duty cycle of the internal oscillator is programmable with the C3 capacitor. Choosing the correct C3 capacitor to obtain the appropriate duty cycle for a particular application circuit is a trial-and-error process. The non-linear effect that C3 produces is dependent on the input voltage and output voltage values. The correct C3 capacitor for specific input and output voltage values cannot be calculated. Choosing the correct C3 capacitance is best done by trial and error, in conjunction with the checking of the inductor peak current to make sure it is not too close to the current limit of the device. As the C3 capacitor value increases, so does the duty cycle; conversely, as the C3 capacitor value decreases, the duty cycle decreases. An incorrect choice of the C3 capacitor can result in the device prematurely tripping the current limit and/or double pulsing, which could lead to the output voltage not being stable. Optimizing the duty cycle for a given set of input/output voltages conditions can be done by referencing the component values in AN-1221 LM2623 General Purpose, Boost Converter Circuit.