SLVS350J October   2002  – May 2019 TPS795

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      TPS79530 Ripple Rejection vs Frequency
      2.      TPS79530 vs Frequency
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 Shutdown
      2. 7.3.2 Start-Up
      3. 7.3.3 Undervoltage Lockout (UVLO)
      4. 7.3.4 Regulator Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation
      2. 7.4.2 Dropout Operation
      3. 7.4.3 Disabled
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Input and Output Capacitor Requirements
        2. 8.2.2.2 Output Noise
        3. 8.2.2.3 Dropout Voltage
        4. 8.2.2.4 Programming the TPS79501 Adjustable LDO Regulator
      3. 8.2.3 Application Curves
    3. 8.3 What to Do and What Not to Do
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Board Layout Recommendation to Improve PSRR and Noise Performance
      2. 10.1.2 Regulator Mounting
      3. 10.1.3 Thermal Considerations
      4. 10.1.4 Estimating Junction Temperature
    2. 10.2 Layout Examples
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 Evaluation Modules
        2. 11.1.1.2 Spice Models
      2. 11.1.2 Device Nomenclature
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

10.1.4 Estimating Junction Temperature

Using the thermal metrics ΨJT and ΨJB, as shown in Thermal Information, the junction temperature can be estimated with corresponding formulas (given in Equation 6). For backwards compatibility, an older θJC,Top parameter is also listed.

Equation 6. TPS795 q_new_metrics_bvs066.gif

where

  • PD is the power dissipation shown by Equation 5
  • TT is the temperature at the center-top of the IC package
  • TB is the PCB temperature measured 1 mm away from the IC package on the PCB surface (see Figure 31)

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 application note SBVA025, Using New Thermal Metrics, available for download at www.ti.com.

As shown in Figure 30, the new thermal metrics (ΨJT and ΨJB) have little dependency on board size. That is, using ΨJT or ΨJB with Equation 6 is a good way to estimate TJ by simply measuring TT or TB, regardless of the application board size.

TPS795 board2_lvs350.gifFigure 30. 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 application report SBVA025, Using New Thermal Metrics, available at www.ti.com.

For further information, see the application report SPRA953, IC Package Thermal Metrics, also available on the TI website.

TPS795 ai_measuring_point_bvs350.gifFigure 31. Measuring Point for TT and TB