SBVS442A December   2022  – October 2025 TPS748A

PRODUCTION DATA  

  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: IOUT = 50mA
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Enable and Shutdown
      2. 6.3.2 Active Discharge
      3. 6.3.3 Power-Good Output (PG)
      4. 6.3.4 Internal Current Limit
      5. 6.3.5 Thermal Shutdown Protection (TSD)
    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
      1. 7.1.1 Input, Output, and Bias Capacitor Requirements
      2. 7.1.2 Dropout Voltage
      3. 7.1.3 Output Noise
      4. 7.1.4 Estimating Junction Temperature
      5. 7.1.5 Soft Start, Sequencing, and Inrush Current
      6. 7.1.6 Power-Good Operation
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
      3. 7.2.3 Application Curve
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
        1. 7.4.1.1 Board Layout
        2. 7.4.1.2 DSQ Package—High CTE Mold Compound
      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

6.3.5 Thermal Shutdown Protection (TSD)

The internal thermal shutdown protection circuit disables the output when the pass transistor TJ reaches TSD(shutdown) (typical). TJ is the thermal junction temperature and TSD(shutdown) (typical) is the thermal shutdown temperature threshold. The thermal shutdown circuit hysteresis verifies the LDO resets (turns on) when the temperature falls to TSD(reset) (typical).

The thermal time constant of the semiconductor die is fairly short. Thus, the device cycles on and off when thermal shutdown is reached until the power dissipation is reduced. Power dissipation during start-up is high from large VIN – VOUT voltage drops across the device or from high inrush currents charging large output capacitors. Under some conditions, the thermal shutdown protection disables the device before start-up completes.

For reliable operation, limit the junction temperature to the maximum listed in the Recommended Operating Conditions table. Operation above this maximum temperature causes the device to exceed operational specifications. Although the internal protection circuitry is designed to protect against thermal overload conditions, this circuitry is not intended to replace proper heat sinking. Continuously running the regulator into thermal shutdown, or above the maximum recommended junction temperature, reduces long-term reliability.