SBVS257 March   2025 TPS7A56

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 Voltage Setting and Regulation
      2. 6.3.2 Low-Noise, Ultra-High Power-Supply Rejection Ratio (PSRR)
      3. 6.3.3 Programmable Soft-Start (NR/SS Pin)
      4. 6.3.4 Precision Enable and UVLO
      5. 6.3.5 Charge Pump Enable and BIAS Rail
      6. 6.3.6 Power-Good Pin (PG Pin)
      7. 6.3.7 Active Discharge
      8. 6.3.8 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
      4. 6.4.4 Current-Limit Operation
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1  Precision Enable (External UVLO)
      2. 7.1.2  Undervoltage Lockout (UVLO) Operation
        1. 7.1.2.1 IN Pin UVLO
        2. 7.1.2.2 BIAS UVLO
        3. 7.1.2.3 Typical UVLO Operation
        4. 7.1.2.4 UVLO(IN) and UVLO(BIAS) Interaction
      3. 7.1.3  Dropout Voltage (VDO)
      4. 7.1.4  Input and Output Capacitor Requirements (CIN and COUT)
      5. 7.1.5  Recommended Capacitor Types
      6. 7.1.6  Soft-Start, Noise Reduction (NR/SS Pin), and Power-Good (PG Pin)
      7. 7.1.7  Optimizing Noise and PSRR
      8. 7.1.8  Adjustable Operation
      9. 7.1.9  Load Transient Response
      10. 7.1.10 Charge Pump Operation
      11. 7.1.11 Sequencing
      12. 7.1.12 Power-Good Functionality
      13. 7.1.13 Paralleling for Higher Output Current and Lower Noise
      14. 7.1.14 Power Dissipation (PD)
      15. 7.1.15 Estimating Junction Temperature
      16. 7.1.16 TPS7A57EVM-056 Thermal Analysis
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
      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 Development Support
      2. 8.1.2 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

7.1.3 Dropout Voltage (VDO)

Generally speaking, dropout voltage (VDO) often refers to the minimum voltage difference between the input and output voltage that is required for regulation. This minimum voltage difference is defined as VDO = VIN – VOUT. When VIN drops to or below the set VDO for the given load current, the device functions as a resistive switch. In this state, the device does not regulate output voltage. When the device operates in dropout, the output voltage tracks the input voltage and dropout voltage (VDO) is proportional to the output current. In this state, the device operates as a resistive switch. Operating the device at or near dropout significantly degrades the device transient performance and PSRR. Maintaining sufficient VOpHr significantly improves device transient performance and PSRR.

Note: If the minimum BIAS rail is set 3.2V above VREF with the internal charge pump disabled, the pass transistor cannot be in BIAS-to-OUT dropout. Thus leaving only the IN-to-OUT dropout conditions to be considered. VREF is the reference pin voltage range, as defined by the Recommended Operating Conditions table. For other operating conditions, see the Undervoltage Lockout (UVLO) Operation section.