JAJSAH6H January   2006  – October 2017 LM3100

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 Hysteretic Control Circuit Overview
    4. 7.4 Device Functional Modes
      1. 7.4.1 Start-up Regulator (VCC)
      2. 7.4.2 Regulation Comparator
      3. 7.4.3 Over-Voltage Comparator
      4. 7.4.4 ON-Time Timer, Shutdown
      5. 7.4.5 Current Limit
      6. 7.4.6 N-Channel Buck Switch and Driver
      7. 7.4.7 Soft-Start
      8. 7.4.8 Thermal Protection
  8. 8 Applications and Implementation
    1. 8.1 Applications Information
      1. 8.1.1 External Components
        1. 8.1.1.1 RFB1 and RFB2
        2. 8.1.1.2 RON
        3. 8.1.1.3 L
        4. 8.1.1.4 CVCC
        5. 8.1.1.5 CO and CO3
        6. 8.1.1.6 CIN and CIN3
        7. 8.1.1.7 CBST
        8. 8.1.1.8 CSS
        9. 8.1.1.9 CFB
    2. 8.2 Typical Application
  9. 9 Layout
    1. 9.1 Layout Guidelines
      1. 9.1.1 PC Board Layout
  10. 10デバイスおよびドキュメントのサポート
    1. 10.1 ドキュメントの更新通知を受け取る方法
    2. 10.2 コミュニティ・リソース
    3. 10.3 商標
    4. 10.4 静電気放電に関する注意事項
    5. 10.5 Glossary
  11. 11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

7.4.4 ON-Time Timer, Shutdown

The ON-Time of LM3100 main switch is determined by the RON resistor and the input voltage (VIN), and is calculated from:

Equation 4. LM3100 20174709.gif

The inverse relationship of tON and VIN results in a nearly constant switching frequency as VIN is varied. RON should be selected for a minimum on-time (at maximum VIN) greater than 200 ns for proper current limit operation. This requirement limits the maximum frequency for each application, depending on VIN and VOUT, calculated from Equation 5:

Equation 5. LM3100 20174710.gif

The LM3100 can be remotely shut down by taking the EN pin below 1.1 V. Refer to Figure 19. In this 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.

For normal operation, the voltage at the EN pin is set between 1.5 V and 3.0 V, depending on VIN and the external pull-up resistor. For all cases, this voltage must be limited not to exceed 7 V.

LM3100 20174704.gifFigure 19. Shutdown Implementation