ZHCS835G March   2012  – October 2023 TPS7A7200

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Pin Configurations
  6. 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
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 User-Configurable Output Voltage
      2. 6.3.2 Traditional Adjustable Configuration
      3. 6.3.3 Undervoltage Lockout (UVLO)
      4. 6.3.4 Soft-Start
      5. 6.3.5 Current Limit
      6. 6.3.6 Enable
      7. 6.3.7 Power-Good
    4. 6.4 Device Functional Modes
      1. 6.4.1 Normal Operation
      2. 6.4.2 Dropout Operation
      3. 6.4.3 Disabled
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 ANY-OUT Programmable Output Voltage
        2. 7.2.2.2 Traditional Adjustable Output Voltage
        3. 7.2.2.3 Input Capacitor Requirements
        4. 7.2.2.4 Output Capacitor Requirements
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
        1. 7.4.1.1 Thermal Considerations
        2. 7.4.1.2 Power Dissipation
        3. 7.4.1.3 Estimating Junction Temperature
      2. 7.4.2 Layout Example
  9. 8 Device And Documentation Support
    1. 8.1 Documentation Support
      1. 8.1.1 Related Documentation
    2. 8.2 接收文档更新通知
    3. 8.3 支持资源
    4. 8.4 Trademarks
    5. 8.5 静电放电警告
    6. 8.6 术语表
  10. 9 Revision History
  11. 10Mechanical, Packaging, And Orderable Information

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7.4.1.3 Estimating Junction Temperature

Using the thermal metrics ΨJT and ΨJB, as listed in the Thermal Information table, the junction temperature can be estimated with corresponding formulas (given in Equation 3). For backwards compatibility, an older θJC,Top parameter is listed as well.

Equation 3. GUID-DA650505-F492-4806-9E0F-5D59BED771A0-low.gif

where:

  • PD is the power dissipation shown by Equation 2
  • TT is the temperature at the center-top of the device package
  • TB is the PCB temperature measured 1 mm away from the device package on the PCB surface (see Figure 7-14)

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 the Using New Thermal Metrics application note.

GUID-1FC4266B-F2F6-4437-A0F6-0C05C8BA76AE-low.gifFigure 7-14 Measuring Points For TT and TB

From Figure 7-15, the new thermal metrics (ΨJT and ΨJB) are shown to have very little dependency on board size. That is, using ΨJT or ΨJB with Equation 3 is a good way to estimate TJ by simply measuring TT or TB, regardless of the application board size.

GUID-F52EC79E-2DBA-413A-9C69-F46028549CE8-low.pngFigure 7-15 ΨJT And ΨJB vs Board Size

For a more detailed discussion of why TI does not recommend using θJC(top) to determine thermal characteristics, see the Using New Thermal Metrics application note. For further information, see the Semiconductor and IC Package Thermal Metrics application note.