SNVS574G July   2008  – July 2019 LM3421 , LM3423

PRODUCTION DATA.  

1. 1 Features
2. 2 Applications
3. 3 Description
   1.     Device Images
      1.      Typical Boost Application
4. 4 Revision History
5. 5 Device Comparison
6. 6 Pin Configuration and Functions
   1.     Pin Functions
7. 7 Specifications
   1. 7.1 Absolute Maximum Ratings
   2. 7.2 ESD Ratings
   3. 7.3 Recommended Operating Conditions
   4. 7.4 Thermal Information
   5. 7.5 Electrical Characteristics
   6. 7.6 Typical Characteristics
8. 8 Detailed Description
   1. 8.1 Overview
   2. 8.2 Functional Block Diagram
   3. 8.3 Feature Description
      1. 8.3.1  Current Regulators
      2. 8.3.2  Predictive Off-Time (PRO) Control
      3. 8.3.3  Average LED Current
      4. 8.3.4  Analog Dimming
      5. 8.3.5  Current Sense and Current Limit
      6. 8.3.6  Overcurrent Protection
      7. 8.3.7  Zero Current Shutdown
      8. 8.3.8  Control Loop Compensation
      9. 8.3.9  Start-Up Regulator
      10. 8.3.10 Overvoltage Lockout (OVLO)
      11. 8.3.11 Input Undervoltage Lockout (UVLO)
          1. 8.3.11.1 UVLO Only
          2. 8.3.11.2 PWM Dimming and UVLO
      12. 8.3.12 PWM Dimming
      13. 8.3.13 LM3423 Only: DPOL, FLT, TIMR, and LRDY
9. 9 Application and Implementation
   1. 9.1 Application Information
      1. 9.1.1 Inductor
      2. 9.1.2 LED Dynamic Resistance
      3. 9.1.3 Output Capacitor
      4. 9.1.4 Input Capacitors
      5. 9.1.5 Main MOSFET / Dimming MOSFET
      6. 9.1.6 Re-Circulating Diode
      7. 9.1.7 Boost Inrush Current
      8. 9.1.8 Switching Frequency
   2. 9.2 Typical Applications
      1. 9.2.1 Basic Topology Schematics
         1. 9.2.1.1 Design Requirements
         2. 9.2.1.2 Detailed Design Procedure
            1. 9.2.1.2.1  Operating Point
            2. 9.2.1.2.2  Switching Frequency
            3. 9.2.1.2.3  Average LED Current
            4. 9.2.1.2.4  Inductor Ripple Current
            5. 9.2.1.2.5  LED Ripple Current
            6. 9.2.1.2.6  Peak Current Limit
            7. 9.2.1.2.7  Loop Compensation
            8. 9.2.1.2.8  Input Capacitance
            9. 9.2.1.2.9  N-channel FET
               1. 9.2.1.2.9.1 Boost and Buck-Boost
            10. 9.2.1.2.10 Diode
            11. 9.2.1.2.11 Output OVLO
            12. 9.2.1.2.12 Input UVLO
            13. 9.2.1.2.13 PWM Dimming Method
            14. 9.2.1.2.14 Analog Dimming Method
      2. 9.2.2 LM3421 Buck-Boost Application
         1. 9.2.2.1 Design Requirements
         2. 9.2.2.2 Detailed Design Procedure
            1. 9.2.2.2.1  Operating Point
            2. 9.2.2.2.2  Switching Frequency
            3. 9.2.2.2.3  Average LED Current
            4. 9.2.2.2.4  Inductor Ripple Current
            5. 9.2.2.2.5  Output Capacitance
            6. 9.2.2.2.6  Peak Current Limit
            7. 9.2.2.2.7  Loop Compensation
            8. 9.2.2.2.8  Input Capacitance
            9. 9.2.2.2.9  N-channel FET
            10. 9.2.2.2.10 Diode
            11. 9.2.2.2.11 Input UVLO
            12. 9.2.2.2.12 Output OVLO
         3. 9.2.2.3 Application Curve
      3. 9.2.3 LM3421 BOOST Application
         1. 9.2.3.1 Design Requirements
         2. 9.2.3.2 Detailed Design Procedure
      4. 9.2.4 LM3421 Buck-Boost Application
         1. 9.2.4.1 Design Requirements
         2. 9.2.4.2 Detailed Design Procedure
      5. 9.2.5 LM3423 Boost Application
         1. 9.2.5.1 Design Requirements
         2. 9.2.5.2 Detailed Design Procedure
      6. 9.2.6 LM3421 Buck-Boost Application
         1. 9.2.6.1 Design Requirements
         2. 9.2.6.2 Detailed Design Procedure
      7. 9.2.7 LM3423 Buck Application
         1. 9.2.7.1 Design Requirements
         2. 9.2.7.2 Detailed Design Procedure
      8. 9.2.8 LM3423 Buck-Boost Application
         1. 9.2.8.1 Design Requirements
         2. 9.2.8.2 Detailed Design Procedure
      9. 9.2.9 LM3421 SEPIC Application
         1. 9.2.9.1 Design Procedure
         2. 9.2.9.2 Detailed Design Procedure
10. 10Power Supply Recommendations
    1. 10.1 General Recommendations
    2. 10.2 Input Supply Current Limit
11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
12. 12Device and Documentation Support
    1. 12.1 Device Support
       1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Related Links
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
13. 13Mechanical, Packaging, and Orderable Information