JAJSG01D June   2012  – August 2018 LMZ20502

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      概略回路図
      2.      VOUT = 1.8V、自動モードでの標準的な効率
  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 System Characteristics
    7. 6.7 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 Nano Scale Package
      2. 7.3.2 Internal Synchronous Rectifier
      3. 7.3.3 Current Limit Protection
      4. 7.3.4 Start-Up
      5. 7.3.5 Dropout Behavior
      6. 7.3.6 Power Good Flag Function
      7. 7.3.7 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 PWM Operation
      2. 7.4.2 PFM Operation
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Detailed Design Procedure
        1. 8.2.1.1 Custom Design With WEBENCH® Tools
        2. 8.2.1.2 Setting The Output Voltage
        3. 8.2.1.3 Output and Feed-Forward Capacitors
        4. 8.2.1.4 Input Capacitors
        5. 8.2.1.5 Maximum Ambient Temperature
        6. 8.2.1.6 Options
      2. 8.2.2 Application Curves
    3. 8.3 Do's and Don'ts
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Soldering Information
  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. 11.1.2 開発サポート
        1. 11.1.2.1 WEBENCH®ツールによるカスタム設計
      3. 11.1.3 ドキュメントのサポート
        1. 11.1.3.1 関連資料
    2. 11.2 ドキュメントの更新通知を受け取る方法
    3. 11.3 コミュニティ・リソース
    4. 11.4 商標
    5. 11.5 静電気放電に関する注意事項
    6. 11.6 Glossary
  12. 12メカニカル、パッケージ、および注文情報
    1. 12.1 Tape and Reel Information

パッケージ・オプション

デバイスごとのパッケージ図は、PDF版データシートをご参照ください。

メカニカル・データ（パッケージ｜ピン）
  • SIL|8
サーマルパッド・メカニカル・データ
発注情報

7.3.3 Current Limit Protection

The LMZ20502 incorporates cycle-by-cycle peak current limit on both the high and low side MOSFETs. This feature limits the output current in case the output is overloaded. During the overload, the peak inductor current is limited to that value found in the Electrical Characteristics table under the heading of "ILIM".

In addition to current limit, a short circuit protection mode is also implemented. When the feedback voltage is brought down to less than 300 mV, but greater than 150 mV, by a short circuit, the synchronous rectifier is turned off. This provides more voltage across the inductor to help maintain the required volt-second balance. If a "harder" short brings the feedback voltage to below 150 mV, the current limit and switching frequency are both reduced to about ½ of the nominal values. In addition, when the current limit is tripped, the device stops switching for about 85 µs. At the end of the time-out, switching resumes and the cycle repeats until the short is removed.

The effect of both overload and short circuit protection can be seen in Figure 9. This graph demonstrates that the device will supply slightly more than 2 A to the load when in overload and much less current during fold-back mode. This is typical behavior for any regulator with this type of current limit protection.

LMZ20502 current_limit_profile_snvs852.pngFigure 9. Typical Current Limit Profile
VIN = 5 V, VOUT = 1.8 V