Datasheet LM340, LM340A, LM7805, LM7812, LM7815 (Texas Instruments) - 14

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LM340, LM340A , LM7805, LM7812 , LM7815
SNOSBT0L – FEBRUARY 2000 – REVISED SEPTEMBER 2016
www.ti.com Application Information (continued) Figure 16. Regulator Floating Ground Figure 17. Transients
When a value for θ(H–A) is found, a heat sink must be selected that has a value that is less than or equal to this number. θ(H–A) is specified numerically by the heat sink manufacturer in this catalog or shown in a curve that plots temperature rise vs power dissipation for the heat sink.
8.2 Typical Applications 8.2.1 Fixed Output Voltage Regulator
The LM340x and LM7805 Family devices are primarily designed to provide fixed output voltage regulation. The simplest implementation of LM340x and LM7805 Family is shown in Figure 18. *Required if the regulator is located far from the power supply filter. **Although no output capacitor is needed for stability, it does help transient response. (If needed, use 0.1-μF, ceramic disc).
Figure 18. Fixed Output Voltage Regulator 8.2.1.1 Design Requirements
The device component count is very minimal. Although not required, TI recommends employing bypass capacitors at the output for optimum stability and transient response. These capacitors must be placed as close as possible to the regulator. If the device is located more than 6 inches from the power supply filter, it is required to employ input capacitor. 14 Submit Documentation Feedback Copyright © 2000–2016, Texas Instruments Incorporated Product Folder Links: LM340 LM340A LM7805 LM7812 LM7815 Document Outline 1 Features 2 Applications 3 Description Table of Contents 4 Revision History 5 Pin Configuration and Functions 6 Specifications 6.1 Absolute Maximum Ratings 6.2 ESD Ratings 6.3 Recommended Operating Conditions 6.4 Thermal Information 6.5 LM340A Electrical Characteristics, VO = 5 V, VI = 10 V 6.6 LM340 / LM7805 Electrical Characteristics, VO = 5 V, VI = 10 V 6.7 LM340 / LM7812 Electrical Characteristics, VO = 12 V, VI = 19 V 6.8 LM340 / LM7815 Electrical Characteristics, VO = 15 V, VI = 23 V 6.9 Typical Characteristics 7 Detailed Description 7.1 Overview 7.2 Functional Block Diagram 7.3 Feature Description 7.3.1 Output Current 7.3.2 Current Limiting Feature 7.3.3 Thermal Shutdown 7.4 Device Functional Modes 8 Application and Implementation 8.1 Application Information 8.1.1 Shorting the Regulator Input 8.1.2 Raising the Output Voltage Above the Input Voltage 8.1.3 Regulator Floating Ground 8.1.4 Transient Voltages 8.2 Typical Applications 8.2.1 Fixed Output Voltage Regulator 8.2.1.1 Design Requirements 8.2.1.2 Detailed Design Procedure 8.2.1.3 Application Curve 8.3 System Examples 9 Power Supply Recommendations 10 Layout 10.1 Layout Guidelines 10.2 Layout Example 10.3 Heat Sinking DDPAK/TO-263 and SOT-223 Package Parts 11 Device and Documentation Support 11.1 Documentation Support 11.1.1 Related Documentation 11.2 Related Links 11.3 Receiving Notification of Documentation Updates 11.4 Community Resources 11.5 Trademarks 11.6 Electrostatic Discharge Caution 11.7 Glossary 12 Mechanical, Packaging, and Orderable Information Page 1