SBVS441 December   2022 TPS7B4255

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.     Timing Characteristics
    7. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Regulated Output (VOUT)
      2. 7.3.2 Undervoltage Lockout
      3. 7.3.3 Thermal Protection
      4. 7.3.4 Current Limit
      5. 7.3.5 VOUT Short to Battery
      6. 7.3.6 Tracking Regulator With an Enable Circuit
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation With VIN < 3 V
      2. 7.4.2 Operation With ADJ/EN Control
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Dropout Voltage
      2. 8.1.2 Reverse Current
      3. 8.1.3 Signal-Buffering LDO
    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 Selection
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Package Mounting
        2. 8.4.1.2 Board Layout Recommendations to Improve PSRR and Noise Performance
        3. 8.4.1.3 Power Dissipation and Thermal Considerations
        4. 8.4.1.4 Thermal Performance Versus Copper Area
      2. 8.4.2 Layout Example
  9. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Device Nomenclature
      2. 9.1.2 Development Support
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  10. 10Mechanical, Packaging, and Orderable Information

Package Options

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

8.4.1.3 Power Dissipation and Thermal Considerations

Equation 2 calculates the device power dissipation.

Equation 2. PD = IOUT × (VIN – VOUT) + IQ × VIN

where:

  • PD = Continuous power dissipation
  • IOUT = Output current
  • VIN = Input voltage
  • VOUT = Output voltage
  • IQ = Quiescent current

Because IQ is much less than IOUT, the term IQ × VIN in Equation 2 can be ignored.

Calculate the junction temperature (TJ) with Equation 3 for a device under operation at a given ambient air temperature (TA).

Equation 3. TJ = TA + (RθJA × PD)

where:

  • RθJA = Junction-to-junction-ambient air thermal impedance

Equation 4 calculates a rise in junction temperature because of power dissipation.

Equation 4. ΔT = TJ – TA = (RθJA × PD)

The maximum ambient air temperature (TAMAX) at which the device can operate can be calculated with Equation 5 for a given maximum junction temperature (TJMAX).

Equation 5. TAMAX = TJMAX – (RθJA × PD)