SLVS338T May   2001  – December 2022 TPS715

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.     Thermal Information
    5. 6.4 Electrical Characteristics
    6. 6.5 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 Wide Supply Range
      2. 7.3.2 Low Quiescent Current
      3. 7.3.3 Dropout Voltage (VDO)
      4. 7.3.4 Current Limit
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation
      2. 7.4.2 Dropout Operation
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Detailed Design Procedure
        1. 8.2.1.1 Setting VOUT for the TPS71501 Adjustable LDO
        2. 8.2.1.2 External Capacitor Requirements
        3. 8.2.1.3 Input and Output Capacitor Requirements
        4. 8.2.1.4 Reverse Current
        5. 8.2.1.5 Feed-Forward Capacitor (CFF)
        6. 8.2.1.6 Power Dissipation (PD)
        7. 8.2.1.7 Estimating Junction Temperature
      2. 8.2.2 Application Curves
    3. 8.3 Best Design Practices
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
        1. 8.5.1.1 Power Dissipation
      2. 8.5.2 Layout Example
  9. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Development Support
        1. 9.1.1.1 Evaluation Module
        2. 9.1.1.2 Spice Models
      2. 9.1.2 Device Nomenclature
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  10. 10Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.3 Dropout Voltage (VDO)

Dropout voltage (VDO) is defined as the input voltage minus the output voltage (VIN – VOUT) at the rated output current (IRATED), where the pass transistor is fully on. IRATED is the maximum IOUT listed in the Recommended Operating Conditions table. In dropout operation, the pass transistor is in the ohmic or triode region of operation, and acts as a switch. The dropout voltage indirectly specifies a minimum input voltage greater than the nominal programmed output voltage at which the output voltage is expected to stay in regulation. If the input voltage falls to less than the value required to maintain output regulation, then the output voltage falls as well.

For a CMOS regulator, the dropout voltage is determined by the drain-source, on-state resistance (RDS(ON)) of the pass transistor. Therefore, if the linear regulator operates at less than the rated current, the dropout voltage for that current scales accordingly. Use Equation 1 to calculate the RDS(ON) of the device.
Equation 1. GUID-20220327-SS0I-TWGK-VSDH-PNWBBPXNPKW3-low.png