SNVS037H September   1999  – March 2024 LM1084

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 Ripple Rejection
      2. 6.3.2 Load Regulation
      3. 6.3.3 Overload Recovery
    4. 6.4 Device Functional Modes
      1. 6.4.1 Output Voltage
      2. 6.4.2 Stability Consideration
      3. 6.4.3 Protection Diodes
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1  1.2-V to 15-V Adjustable Regulator
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
        3. 7.2.1.3 Application Curve
      2. 7.2.2  Adjustable at 5 V
      3. 7.2.3  5-V Regulator With Shutdown
      4. 7.2.4  Battery Charger
      5. 7.2.5  Adjustable Fixed Regulator
      6. 7.2.6  Regulator with Reference
      7. 7.2.7  High Current Lamp Driver Protection
      8. 7.2.8  Battery Backup Regulated Supply
      9. 7.2.9  Ripple Rejection Enhancement
      10. 7.2.10 Automatic Light Control
      11. 7.2.11 Generating Negative Supply Voltage
      12. 7.2.12 Remote Sensing
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
        1. 7.4.1.1 Thermal Considerations
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Receiving Notification of Documentation Updates
    2. 8.2 Support Resources
    3. 8.3 Trademarks
    4. 8.4 Electrostatic Discharge Caution
    5. 8.5 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

6.1 Overview

A basic functional diagram for the LM1084-ADJ (excluding protection circuitry) is shown in Figure 6-1. The topology is basically that of the LM317 except for the pass transistor. Instead of a Darlington NPN with its two diode voltage drop, the LM1084 uses a single NPN. This results in a lower dropout voltage. The structure of the pass transistor is also known as a quasi LDO. The advantage of a quasi LDO over a PNP LDO is its inherently lower quiescent current. The LM1084 is ensured to provide a minimum dropout voltage of 1.5-V over temperature, at full load.

GUID-0124CE39-1FEE-4DC9-BE38-851DD5E36B8D-low.pngFigure 6-1 Basic Functional Diagram for the LM1084, Excluding Protection Circuitry