JAJSI66A November   2019  – March 2020 TPS7A54

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      デジタル負荷の電源
      2.      RFコンポーネントの電源
  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 Voltage Regulation Features
        1. 8.3.1.1 DC Regulation
        2. 8.3.1.2 AC and Transient Response
      2. 8.3.2 System Start-Up Features
        1. 8.3.2.1 Programmable Soft Start (NR/SS Pin)
        2. 8.3.2.2 Internal Sequencing
          1. 8.3.2.2.1 Enable (EN)
          2. 8.3.2.2.2 Undervoltage Lockout (UVLO) Control
          3. 8.3.2.2.3 Active Discharge
        3. 8.3.2.3 Power-Good Output (PG)
      3. 8.3.3 Internal Protection Features
        1. 8.3.3.1 Foldback Current Limit (ICL)
        2. 8.3.3.2 Thermal Protection (Tsd)
    4. 8.4 Device Functional Modes
      1. 8.4.1 Regulation
      2. 8.4.2 Disabled
      3. 8.4.3 Current Limit Operation
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1  Recommended Capacitor Types
        1. 9.1.1.1 Input and Output Capacitor Requirements (CIN and COUT)
        2. 9.1.1.2 Noise-Reduction and Soft-Start Capacitor (CNR/SS)
        3. 9.1.1.3 Feed-Forward Capacitor (CFF)
      2. 9.1.2  Soft Start and Inrush Current
      3. 9.1.3  Optimizing Noise and PSRR
      4. 9.1.4  Charge Pump Noise
      5. 9.1.5  Current Sharing
      6. 9.1.6  Adjustable Operation
      7. 9.1.7  Power-Good Operation
      8. 9.1.8  Undervoltage Lockout (UVLO) Operation
      9. 9.1.9  Dropout Voltage (VDO)
      10. 9.1.10 Device Behavior During Transition From Dropout Into Regulation
      11. 9.1.11 Load Transient Response
      12. 9.1.12 Reverse Current Protection Considerations
      13. 9.1.13 Power Dissipation (PD)
      14. 9.1.14 Estimating Junction Temperature
      15. 9.1.15 TPS7A54EVM Thermal Analysis
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Board Layout
    2. 11.2 Layout Example
  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 開発サポート
        1. 12.1.1.1 評価基板
        2. 12.1.1.2 SPICEモデル
      2. 12.1.2 デバイスの項目表記
    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 ドキュメントの更新通知を受け取る方法
    4. 12.4 コミュニティ・リソース
    5. 12.5 商標
    6. 12.6 静電気放電に関する注意事項
    7. 12.7 Glossary
  13. 13メカニカル、パッケージ、および注文情報

9.1.14 Estimating Junction Temperature

The JEDEC standard now recommends the use of psi (Ψ) thermal metrics to estimate the junction temperatures of the LDO when in-circuit on a typical PCB board application. These metrics are not strictly speaking thermal resistances, but rather offer practical and relative means of estimating junction temperatures. These psi metrics are determined to be significantly independent of the copper-spreading area. The key thermal metrics (ΨJT and ΨJB) are used in accordance with Equation 8 and are given in the Electrical Characteristics table.

Equation 8. TPS7A54 q_wjt-wjb_bvs204.gif

where

  • PD is the power dissipated as explained in Equation 5
  • TT is the temperature at the center-top of the device package
  • TB is the PCB surface temperature measured 1 mm from the device package and centered on the package edge