SLVS521H July   2004  – December 2023 LP2981 , LP2981A

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
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Output Enable
      2. 6.3.2 Dropout Voltage
      3. 6.3.3 Current Limit
      4. 6.3.4 Undervoltage Lockout (UVLO)
      5. 6.3.5 Thermal Shutdown
      6. 6.3.6 Output Pulldown
    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 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Recommended Capacitor Types
        1. 7.1.1.1 Recommended Capacitors for the Legacy Chip
          1. 7.1.1.1.1 Tantalum Capacitors
          2. 7.1.1.1.2 Ceramic Capacitors
          3. 7.1.1.1.3 Aluminum Capacitors
        2. 7.1.1.2 Recommended Capacitors for the New Chip
      2. 7.1.2 Input and Output Capacitor Requirements
        1. 7.1.2.1 Input Capacitor
        2. 7.1.2.2 Output Capacitor
      3. 7.1.3 Estimating Junction Temperature
      4. 7.1.4 Power Dissipation (PD)
      5. 7.1.5 Reverse Current
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 ON and OFF Input Operation
      3. 7.2.3 Application Curves
  9. 8 Power Supply Recommendations
  10. 9 Layout
    1. 9.1 Layout Guidelines
    2. 9.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Nomenclature
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

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

6.3.5 Thermal Shutdown

The device contains a thermal shutdown protection circuit to disable the device when the junction temperature (TJ) of the pass transistor rises to TSD(shutdown) (typical). Thermal shutdown hysteresis makes sure that the device resets (turns on) when the temperature falls to TSD(reset) (typical). Thermal shutdown circuit specifications are defined in Section 5.5.

The thermal time-constant of the semiconductor die is fairly short, thus the device can cycle on and off when thermal shutdown is reached until power dissipation is reduced. Power dissipation during start up can be 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 Section 5.3 table. Operation above this maximum temperature causes the device to exceed operational specifications. Although the internal protection circuitry of the device is designed to protect against thermal overall conditions, this circuitry is not intended to replace proper heat sinking. Continuously running the device into thermal shutdown or above the maximum recommended junction temperature reduces long-term reliability.