JAJSH78J June   2010  – April 2019 LMZ10503EXT

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
      2.      VOUT = 3.3Vでの効率
  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 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 Enable
      2. 8.3.2 Enable and UVLO
      3. 8.3.3 Soft-Start
      4. 8.3.4 Soft-Start Capacitor
      5. 8.3.5 Tracking
      6. 8.3.6 Tracking - Equal Soft-Start Time
      7. 8.3.7 Tracking - Equal Slew Rates
      8. 8.3.8 Current Limit
      9. 8.3.9 Overtemperature Protection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Prebias Start-Up Capability
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Custom Design With WEBENCH® Tools
        2. 9.2.2.2 Input Capacitor Selection
        3. 9.2.2.3 Output Capacitor Selection
          1. 9.2.2.3.1 Output Voltage Setting
        4. 9.2.2.4 Loop Compensation
      3. 9.2.3 Application Curves
    3. 9.3 System Examples
      1. 9.3.1 Application Schematic for 3.3-V to 5-V Input and 2.5-V Output With Optimized Ripple and Transient Response
      2. 9.3.2 Application Schematic for 3.3-V to 5-V Input and 2.5-V Output
      3. 9.3.3 EMI Tested Schematic for 2.5-V Output Based on 3.3-V to 5-V Input
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Examples
    3. 11.3 Estimate Power Dissipation and Thermal Considerations
    4. 11.4 Power Module SMT Guidelines
  12. 12デバイスおよびドキュメントのサポート
    1. 12.1 デバイス・サポート
      1. 12.1.1 デベロッパー・ネットワークの製品に関する免責事項
      2. 12.1.2 開発サポート
        1. 12.1.2.1 WEBENCH®ツールによるカスタム設計
    2. 12.2 ドキュメントのサポート
      1. 12.2.1 関連資料
    3. 12.3 コミュニティ・リソース
    4. 12.4 商標
    5. 12.5 静電気放電に関する注意事項
    6. 12.6 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

8.3.6 Tracking - Equal Soft-Start Time

One way to use the tracking feature is to design the tracking resistor divider so that the master supply output voltage, VOUT1, and the LMZ10503EXT output voltage, VOUT2, both rise together and reach their target values at the same time. This is termed ratiometric start-up. For this case, the equation governing the values of tracking divider resistors Rtrkb and Rtrkt is given by:

Equation 4. LMZ10503EXT eq_24_SNVS610.gif

Equation 4 includes an offset voltage, of 200 mV, to ensure that the final value of the SS pin voltage exceeds the reference voltage of the LMZ10503EXT. This offset will cause the LMZ10503EXT output voltage to reach regulation slightly before the master supply. For a value of 33 kΩ, 1% is recommended for Rtrkt as a compromise between high-precision and low-quiescent current through the divider while minimizing the effect of the 2-µA soft-start current source.

For example, if the master supply voltage VOUT1 is 3.3 V and the LMZ10503EXT output voltage was 1.8 V, then the value of Rtrkb needed to give the two supplies identical soft-start times would be 14.3 kΩ. Figure 19 shows an example of tracking using equal soft-start time.

LMZ10503EXT 30118259.gifFigure 19. Timing Diagram for Tracking Using Equal Soft-Start Time