SBVS355C June   2019  – May 2022 TPS745-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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 Timing Requirements
    7. 6.7 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 TPS745-Q1 Comparison
      2. 7.3.2 Undervoltage Lockout (UVLO)
      3. 7.3.3 Shutdown
      4. 7.3.4 Foldback Current Limit
      5. 7.3.5 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Device Functional Mode Comparison
      2. 7.4.2 Normal Operation
      3. 7.4.3 Dropout Operation
      4. 7.4.4 Disabled
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Adjustable Device Feedback Resistors
      2. 8.1.2 Input and Output Capacitor Selection
      3. 8.1.3 Dropout Voltage
      4. 8.1.4 Exiting Dropout
      5. 8.1.5 Reverse Current
      6. 8.1.6 Power Dissipation (PD)
      7. 8.1.7 Power-Good Function
      8. 8.1.8 Feed-Forward Capacitor (CFF)
      9. 8.1.9 Start-Up Sequencing
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Input Current
        2. 8.2.2.2 Thermal Dissipation
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Device Nomenclature
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support 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

8.2.2.2 Thermal Dissipation

The junction temperature can be determined using the junction-to-ambient thermal resistance (RθJA) and the total power dissipation (PD). Use Equation 7 to calculate the power dissipation. Multiply PD by RθJA as Equation 8 shows and add the ambient temperature (TA) to calculate the junction temperature (TJ).

Equation 7. PD = (IGND+ IOUT) × (VIN – VOUT)
Equation 8. TJ = RθJA × PD + TA

Calculate the maximum ambient temperature according to Equation 9 and Equation 10. The maximum ambient temperature is 113.86°C for the example conditions.

Equation 9. TA(MAX) = TJ(MAX) – RθJA × PD
Equation 10. TA(MAX) = 150°C – 80.3°C/W × (3.3 V – 1.8 V) × (0.3 A) = 113.86°C