SNVS540K March   2009  – April 2019 LM2840 , LM2841 , LM2842

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Circuit
  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
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 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 Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Continuous Conduction Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Setting the Output Voltage
        3. 8.2.2.3 Inductor Selection
        4. 8.2.2.4 Input Capacitor
        5. 8.2.2.5 Output Capacitor
        6. 8.2.2.6 Bootstrap Capacitor
        7. 8.2.2.7 Soft-Start Components
        8. 8.2.2.8 Shutdown Operation
        9. 8.2.2.9 Schottky Diode
      3. 8.2.3 Application Curves
      4. 8.2.4 Other Application Circuits
  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 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Development Support
        1. 11.1.2.1 Custom Design With WEBENCH® Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Related Links
    4. 11.4 Receiving Notification of Documentation Updates
    5. 11.5 Community Resources
    6. 11.6 Trademarks
    7. 11.7 Electrostatic Discharge Caution
    8. 11.8 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

10.1 Layout Guidelines

To reduce problems with conducted noise pickup, the ground side of the feedback network should be connected directly to the GND pin with its own connection. The feedback network, resistors R1 and R2, must be kept close to the FB pin, and away from the inductor to minimize coupling noise into the feedback pin. The input bypass capacitor CIN must be placed close to the VIN pin. This reduces copper trace resistance, which effects input voltage ripple of the IC. The inductor L1 must be placed close to the SW pin to reduce EMI and capacitive coupling. The output capacitor, COUT must be placed close to the junction of L1 and the diode D1. The L1, D1, and COUT trace must be as short as possible to reduce conducted and radiated noise and increase overall efficiency. The ground connection for the diode, CIN, and COUT must be as small as possible and tied to the system ground plane in only one spot (preferably at the COUT ground point) to minimize conducted noise in the system ground plane. See Layout Guidelines for Switching Power Supplies for more detail on switching power supply layout considerations.