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

8.2.2.5 Output Capacitor

The selection of COUT is driven by the maximum allowable output voltage ripple. The output ripple in the constant frequency, PWM mode is approximated by Equation 6.

Equation 6. VRIPPLE = IRIPPLE (ESR + (1 / (8fSWCOUT)))

The ESR term usually plays the dominant role in determining the voltage ripple. Low-ESR ceramic capacitors are recommended. Capacitors in the range of 22 µF to 100 µF are a good starting point with an ESR of 0.1 Ω or less.

Table 3. Recommended Input and Output Capacitors

MANUFACTURER CAPACITOR CONTACT INFORMATION
Vishay Sprague 293D, 592D, and 595D series tantalum www.vishay.com
407-324-4140
Taiyo Yuden High capacitance MLCC ceramic www.t-yuden.com
408-573-4150
Cornell Dubilier ESRD seriec Polymer Aluminum Electrolytic
SPV and AFK series V-chip series		 www.cde.com
MuRata High capacitance MLCC ceramic www.murata.com