SBVS437B December   2022  – February 2024 TPS7A21-Q1

PRODMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  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 Smart Enable (EN)
      2. 6.3.2 Low Output Noise
      3. 6.3.3 Active Discharge
      4. 6.3.4 Dropout Voltage
      5. 6.3.5 Foldback Current Limit
      6. 6.3.6 Undervoltage Lockout
      7. 6.3.7 Thermal Overload Protection (TSD)
    4. 6.4 Device Functional Modes
      1. 6.4.1 Device Functional Mode Comparison
      2. 6.4.2 Normal Operation
      3. 6.4.3 Dropout Operation
      4. 6.4.4 Disabled
  8. 7 Applications and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Recommended Capacitor Types
      2. 7.1.2 Input and Output Capacitor Requirements
      3. 7.1.3 Load Transient Response
      4. 7.1.4 Undervoltage Lockout (UVLO) Operation
      5. 7.1.5 Power Dissipation (PD)
      6. 7.1.6 Estimating Junction Temperature
      7. 7.1.7 Recommended Area For Continuous Operation
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Power Dissipation and Device Operation
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Device Nomenclature
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information
    1. 10.1 Mechanical Data

Package Options

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

7.1.6 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 5 and are given in the Thermal Information table.

Equation 5. ΨJT : TJ = TT + ΨJT × PD and ΨJB : TJ = TB + ΨJB × PD

where:

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