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

11.3 Estimate Power Dissipation and Thermal Considerations

Use the current derating curves in the Typical Characteristics section to obtain an estimate of power loss (PIC_LOSS). For the design case of VIN = 5 V, VOUT = 2.5 V, IOUT = 3 A, TA(MAX) = 85°C , and TJ(MAX) = 125°C, the device must see a thermal resistance from case to ambient (θCA) of less than:

Equation 21. LMZ10503EXT eq_23_SNVS610.gif
Equation 22. LMZ10503EXT eq_5_SNVS669.gif

Given the typical thermal resistance from junction to case (θJC) to be 1.9°C/W (typical). Continuously operating at a TJ greater than 125°C will have a shorten lifespan.

To reach θCA = 69.5°C/W, the PCB is required to dissipate heat effectively. With no airflow and no external heat, a good estimate of the required board area covered by 1-oz. copper on both the top and bottom metal layers is:

Equation 23. LMZ10503EXT eq_22_SNVS610.gif
Equation 24. LMZ10503EXT eq_9_SNVS668.gif

As a result, approximately 7.2 square cm of 1-oz. copper on top and bottom layers is required for the PCB design.

The PCB copper heat sink must be connected to the exposed pad (EP). Approximately thirty six, 8 mils thermal vias spaced 59 mils (1.5 mm) apart must connect the top copper to the bottom copper. For an extended discussion and formulations of thermal rules of thumb, refer to AN-2020 Thermal Design By Insight, Not Hindsight (SNVA419). For an example of a high thermal performance PCB layout with θJA of 20°C/W, refer to the evaluation board application note AN-2074 LMZ1050xEXT Evaluation Board (SNVA450) and for results of a study of the effects of the PCB designs, refer to AN-2026 Effect of PCB Design on Thermal Performance of SIMPLE SWITCHER Power Modules (SNVA424).