SNVS113F December   1999  – May 2016 LM3411

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics: 3.3-V Version
    6. 6.6 Electrical Characteristics: 5-V Version
    7. 6.7 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1  LM3411 Typical Application
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Compensation
          2. 9.2.1.2.2 Test Circuit
        3. 9.2.1.3 Application Curves
      2. 9.2.2  Isolated 250-mA Flyback Switching Regulator
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
      3. 9.2.3  Isolated 1.5-A Flyback Switching Regulator
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
      4. 9.2.4  Precision 1-A Buck Regulator
        1. 9.2.4.1 Design Requirements
        2. 9.2.4.2 Detailed Design Procedure
      5. 9.2.5  Negative Input, Negative or Positive Output Flyback Regulator
        1. 9.2.5.1 Design Requirements
        2. 9.2.5.2 Detailed Design Procedure
      6. 9.2.6  Precision 5-V, 1-A Low Dropout Regulator
        1. 9.2.6.1 Design Requirements
        2. 9.2.6.2 Detailed Design Procedure
      7. 9.2.7  3.3-V, 0.5-A Low Dropout Regulator
        1. 9.2.7.1 Design Requirements
        2. 9.2.7.2 Detailed Design Procedure
      8. 9.2.8  Precision Positive Voltage Regulator With Accurate Current Limit
        1. 9.2.8.1 Design Requirements
        2. 9.2.8.2 Detailed Design Procedure
      9. 9.2.9  Precision Negative Voltage Regulator
        1. 9.2.9.1 Design Requirements
        2. 9.2.9.2 Detailed Design Procedure
      10. 9.2.10 4.7-V Power ON Detector With Hysteresis
        1. 9.2.10.1 Detailed Design Procedure
      11. 9.2.11 ±50-mV External Trim
        1. 9.2.11.1 Detailed Design Procedure
      12. 9.2.12 250-mA Shunt Regulator
        1. 9.2.12.1 Design Requirements
        2. 9.2.12.2 Detailed Design Procedure
      13. 9.2.13 Voltage Detector
        1. 9.2.13.1 Detailed Design Procedure
      14. 9.2.14 Overvoltage Crowbar
        1. 9.2.14.1 Detailed Design Procedure
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8 Detailed Description

8.1 Overview

The LM3411 is a shunt regulator specifically designed to be the reference and control section in an overall feedback loop of a regulated power supply. The regulated output voltage is sensed between the IN pin and GROUND pin of the LM3411. If the voltage at the IN pin is less than the LM3411 regulating voltage (VREG), the OUT pin sources no current. As the voltage at the IN pin approaches the VREG voltage, the OUT pin begins sourcing current. This current is then used to drive a feedback device, (optocoupler) or a power device (linear regulator, switching regulator, and so forth) which serves the output voltage to be the same value as VREG.

In some applications (even under normal operating conditions), the voltage on the IN pin can be forced above the VREG voltage. In these instances, the maximum voltage applied to the IN pin should not exceed 20 V. In addition, an external resistor may be required on the OUT pin to limit the maximum current to 20 mA.

8.2 Functional Block Diagrams

LM3411 01198702.gif Figure 17. LM3411 Functional Diagram
LM3411 01198729.gif Figure 18. Detailed Schematic

8.3 Feature Description

The LM3411 devices contain an internal operational amplifier, precision reference, feedback resister divider, and a bi-polar transistor suitable for driving an optocoupler. The divider resistor is sized such that the system will regulate the +IN pin to either 3.3 V or 5 V depending on the device version used. By connecting a feedback network from the OUT pin to the COMP pin, local compensation is implemented to stabilize the system.

8.4 Device Functional Modes

The primary mode of operation for the LM3411 is as a shunt regulator. In addition the device has robust overcurrent protection. These features make it applicable to a wide range of applications ranging from isolated feedback control to traditional shunt regulation.