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

7.2.2.7 Polarity Reversal Protection

In many applications, a voltage regulator powers a load that is not connected to ground. Instead, the regulator is connected to a voltage source of the opposite polarity (for example, operational amplifiers, level-shifting circuits, and so on). During start-up and short-circuit events, this connection leads to polarity reversal of the regulator output and potentially damages the internal components of the regulator.

To avoid polarity reversal on the regulator output, use external protection to protect the device.

Figure 7-3 shows one approach for protecting the device.

uA78M-Q1 Example Circuit for Polarity Reversal Protection Using a Schottky DiodeFigure 7-3 Example Circuit for Polarity Reversal Protection Using a Schottky Diode