SLVS056P May   1976  – January 2015

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Simplified Schematic
  5. 5 Revision History
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics — uA7805
    6. 7.6  Electrical Characteristics — uA7808
    7. 7.7  Electrical Characteristics — uA7810
    8. 7.8  Electrical Characteristics — uA7812
    9. 7.9  Electrical Characteristics — uA7815
    10. 7.10 Electrical Characteristics — uA7824
    11. 7.11 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Schematic
    3. 8.3 Feature Description
      1. 8.3.1 Thermal Overload
      2. 8.3.2 Short-Circuit Current Limiting
    4. 8.4 Device Functional Modes
      1. 8.4.1 Fixed-Output Mode
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Operation With a Load Common to a Voltage of Opposite Polarity
        2. 9.2.2.2 Reverse-Bias Protection
      3. 9.2.3 Application Curves
      4. 9.2.4 General Configurations
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Related Links
    2. 12.2 Trademarks
    3. 12.3 Electrostatic Discharge Caution
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

9.1 Application Information

The following section shows application details of the µA78xx as a linear regulator.

9.2 Typical Application

ai_fixed_output.gifFigure 2. Fixed-Output Regulator

9.2.1 Design Requirements

  • Input supply capacitor recommended for filtering noise on the input
  • Output supply decoupling capacitor for stabilizing the output

9.2.2 Detailed Design Procedure

9.2.2.1 Operation With a Load Common to a Voltage of Opposite Polarity

In many cases, a regulator powers a load that is not connected to ground but, instead, is connected to a voltage source of opposite polarity (e.g., operational amplifiers, level-shifting circuits, etc.). In these cases, a clamp diode should be connected to the regulator output as shown in Figure 3. This protects the regulator from output polarity reversals during startup and short-circuit operation.

ai_out_polar_rev.gifFigure 3. Output Polarity-Reversal-Protection Circuit

9.2.2.2 Reverse-Bias Protection

Occasionally, the input voltage to the regulator can collapse faster than the output voltage. This can occur, for example, when the input supply is crowbarred during an output overvoltage condition. If the output voltage is greater than approximately 7 V, the emitter-base junction of the series-pass element (internal or external) could break down and be damaged. To prevent this, a diode shunt can be used as shown in Figure 4.

ai_rev_bias_prot.gifFigure 4. Reverse-Bias-Protection Circuit

9.2.3 Application Curves

ua7805_dropoutvoltage.gifFigure 5. µA7805 Voltage Loss vs Output Current at 25°C

9.2.4 General Configurations

ai_pos_in_neg_cfg.gifFigure 6. Positive Regulator in Negative Configuration (VI Must Float)
ai_adj_output.gifFigure 7. Adjustable-Output Regulator
ai_current_reg.gifFigure 8. Current Regulator
ai_reg_dual_supply.gifFigure 9. Regulated Dual Supply