JAJSAV1G September   2007  – January 2018 LM3103

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     代表的なアプリケーションの回路図
  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 Functional Block Diagram
    2. 7.2 Feature Description
      1. 7.2.1  COT Control Circuit Overview
      2. 7.2.2  Startup Regulator (VCC)
      3. 7.2.3  Regulation Comparator
      4. 7.2.4  Zero Coil Current Detect
      5. 7.2.5  Over-Voltage Comparator
      6. 7.2.6  ON-Time Timer, Shutdown
      7. 7.2.7  Current Limit
      8. 7.2.8  N-Channel MOSFET and Driver
      9. 7.2.9  Soft-Start
      10. 7.2.10 Thermal Protection
  8. 8 Applications and Implementation
    1. 8.1 Application Information
      1. 8.1.1 External Components
  9. 9 デバイスおよびドキュメントのサポート
    1. 9.1 ドキュメントの更新通知を受け取る方法
    2. 9.2 コミュニティ・リソース
    3. 9.3 商標
    4. 9.4 静電気放電に関する注意事項
    5. 9.5 Glossary
  10. 10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

7.2.6 ON-Time Timer, Shutdown

The on-time of the LM3103 main MOSFET is determined by the resistor RON and the input voltage VIN. It is calculated as follows:

Equation 4. LM3103 30029724.gif

The inverse relationship of ton and VIN gives a nearly constant frequency as VIN is varied. RON should be selected such that the on-time at maximum VIN is greater than 100 ns. The on-timer has a limiter to ensure a minimum of 100 ns for ton. This limits the maximum operating frequency, which is governed by the following equation:

Equation 5. LM3103 30029725.gif

The LM3103 can be remotely shut down by pulling the voltage of the EN pin below 1.6 V. In this shutdown mode, the SS pin is internally grounded, the on-timer is disabled, and bias currents are reduced. Releasing the EN pin allows normal operation to resume because the EN pin is internally pulled up.

LM3103 30029726.pngFigure 19. Shutdown Implementation