SNVS629F May   2011  – December 2019 LM5050-1 , LM5050-1-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Full Application
      2.      Typical Redundant Supply Configuration
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings: LM5050-1
    3. 6.3 ESD Ratings: LM5050-1-Q1
    4. 6.4 Recommended Operating Conditions
    5. 6.5 Thermal Information
    6. 6.6 Electrical Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 IN, GATE, and OUT Pins
      2. 7.3.2 VS Pin
      3. 7.3.3 OFF Pin
    4. 7.4 Device Functional Modes
      1. 7.4.1 ON/OFF Control Mode
      2. 7.4.2 External Power Supply Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 MOSFET Selection
      2. 8.1.2 Short Circuit Failure of an Input Supply
    2. 8.2 Typical Applications
      1. 8.2.1 Typical Application With Input and Output Transient Protection
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Power Supply Components (R1 C1,) Selection
          2. 8.2.1.2.2 MOSFET (Q1) Selection
          3. 8.2.1.2.3 D1 and D2 Selection for Inductive Kick-Back Protection
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Using a Separate VS Supply for Low Vin Operation
      3. 8.2.3 ORing of Two Power Sources
      4. 8.2.4 Reverse Input Voltage Protection With IQ Reduction
      5. 8.2.5 Basic Application With Input Transient Protection
      6. 8.2.6 48-V Application With Reverse Input Voltage (VIN = –48 V) Protection
        1. 8.2.6.1 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Related Links
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.1 Application Information

Systems that require high availability often use multiple, parallel-connected redundant power supplies to improve reliability. Schottky OR-ing diodes are typically used to connect these redundant power supplies to a common point at the load. The disadvantage of using OR-ing diodes is the forward voltage drop, which reduces the available voltage and the associated power losses as load currents increase. Using an N-channel MOSFET to replace the OR-ing diode requires a small increase in the level of complexity, but reduces, or eliminates, the need for diode heat sinks or large thermal copper area in circuit board layouts for high power applications.

LM5050-1 LM5050-1-Q1 30104832.gifFigure 21. OR-ing with Diodes

The LM5050-1/-Q1 is a positive voltage (that is, high-side) OR-ing controller that will drive an external N-channel MOSFET to replace an OR-ing diode. The voltage across the MOSFET source and drain pins is monitored by the LM5050-1 at the IN and OUT pins, while the GATE pin drives the MOSFET to control its operation based on the monitored source-drain voltage. The resulting behavior is that of an ideal rectifier with source and drain pins of the MOSFET acting as the anode and cathode pins of a diode respectively.

LM5050-1 LM5050-1-Q1 30104833.gifFigure 22. OR-ing With MOSFETs