SLVS537C June   2004  – May 2025 UA78M-Q1

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: UA78M33Q (Both Legacy and New Chip)
    6. 5.6 Electrical Characteristics: UA78M05Q (Both Legacy and New Chip)
    7. 5.7 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagrams
    3. 6.3 Feature Description
      1. 6.3.1 Current Limit
      2. 6.3.2 Dropout Voltage (VDO)
      3. 6.3.3 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Normal Operation
      2. 6.4.2 Dropout Operation
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Input and Output Capacitor Requirements
        2. 7.2.2.2 Power Dissipation (PD)
        3. 7.2.2.3 Estimating Junction Temperature
        4. 7.2.2.4 External Capacitor Requirements
        5. 7.2.2.5 Overload Recovery
        6. 7.2.2.6 Reverse Current
        7. 7.2.2.7 Polarity Reversal Protection
      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
        1. 8.1.1.1 Evaluation Module
      2. 8.1.2 Device Nomenclature
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.3.2 Dropout Voltage (VDO)

Dropout voltage (VDO) is defined as VIN – VOUT at the rated output current (IRATED), where the pass transistor is fully on. VIN is the input voltage, VOUT is the output voltage, and IRATED is the maximum IOUT listed in the Recommended Operating Conditions table. At this operating point, the pass transistor is driven fully on. Dropout voltage indirectly specifies a minimum input voltage greater than the nominal programmed output voltage where the output voltage is expected to stay in regulation. If the input voltage falls to less than the nominal output regulation, then the output voltage falls as well.