JAJS408M June   2008  – June 2018 TPS735

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     代表的なアプリケーション
  4. 4 改訂履歴
    1.     Pin Configuration and Functions
      1.      Pin Functions
  5. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  6. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagrams
    3. 6.3 Feature Description
      1. 6.3.1 Internal Current Limit
      2. 6.3.2 Shutdown
      3. 6.3.3 Dropout Voltage
      4. 6.3.4 Start-Up and Noise Reduction Capacitor
      5. 6.3.5 Transient Response
      6. 6.3.6 Undervoltage Lockout
      7. 6.3.7 Minimum Load
      8. 6.3.8 Thermal Protection
    4. 6.4 Device Functional Modes
      1. 6.4.1 Normal Operation
      2. 6.4.2 Dropout Operation
      3. 6.4.3 Disabled
  7. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Design Requirements
        1. 7.2.1.1 Input and Output Capacitor Requirements
        2. 7.2.1.2 Feed-Forward Capacitor Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Output Noise
      3. 7.2.3 Application Curves
  8. 8 Power Supply Recommendations
  9. 9 Layout
    1. 9.1 Layout Guidelines
      1. 9.1.1 Board Layout Recommendations to Improve PSRR and Noise Performance
    2. 9.2 Layout Example
    3. 9.3 Power Dissipation
    4. 9.4 Estimating Junction Temperature
    5. 9.5 Package Mounting
  10. 10デバイスおよびドキュメントのサポート
    1. 10.1 デバイス・サポート
      1. 10.1.1 開発サポート
        1. 10.1.1.1 評価モジュール
      2. 10.1.2 デバイスの項目表記
    2. 10.2 ドキュメントのサポート
      1. 10.2.1 関連資料
    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

9.4 Estimating Junction Temperature

Using the thermal metrics ΨJT and ΨJB, as the table shows, the junction temperature can be estimated with corresponding formulas (Equation 5), which are more accurate than the value of TJ through calculation with θJA.

Equation 5. TPS735 q_new_metrics_bvs066.gif

where

  • PD is the power dissipation calculated with Equation 2,
  • TT is the temperature at the center-top of the device package, and
  • TB is the PCB temperature measured 1 mm away from the device package on the PCB surface (as shown in Figure 25).

NOTE

Both TT and TB can be measured on actual application boards using a thermo‐gun (an infrared thermometer).

For more information about measuring TT and TB, see Using New Thermal Metrics, available for download at www.ti.com.

According to Figure 24, the new thermal metrics (ΨJT and ΨJB) do not depend on the copper area. Using ΨJT or ΨJB with Equation 5 can estimate TJ by measuring TT or TB on an application board.

TPS735 ai_psi_jt_jb_bvs087.gifFigure 24. ΨJT and ΨJB vs Board Size
TPS735 ai_thermal_measmt_bvs087.gif
1. Power dissipation may limit operating range. See .
Figure 25. Measuring Points for TT and TB