SNVS570M January   2009  – November 2015 LM3445

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
    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  Overview of Phase Control Dimming
      2. 7.3.2  Theory of Operation
      3. 7.3.3  Sensing the Rectified TRIAC Waveform
      4. 7.3.4  LM3445 Line Sensing Circuitry
      5. 7.3.5  TRIAC Holding Current Resistor
      6. 7.3.6  Angle Detect
      7. 7.3.7  Bleeder
      8. 7.3.8  FLTR1 Pin
      9. 7.3.9  Dim Decoder
      10. 7.3.10 Valley-Fill Circuit
      11. 7.3.11 Valley-Fill Operation
      12. 7.3.12 Buck Converter
      13. 7.3.13 Overview of Constant Off-Time Control
      14. 7.3.14 Master/Slave Operation
      15. 7.3.15 Master/Slave Configuration
      16. 7.3.16 Master Board Modifications
      17. 7.3.17 Slave Board Modifications
      18. 7.3.18 Master/Slave Interconnection
      19. 7.3.19 Master/Slave Theory of Operation
      20. 7.3.20 Master/Slave Connection Diagram
      21. 7.3.21 Master/Slave Block Diagrams
      22. 7.3.22 Thermal Shutdown
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Determining Duty-Cycle (D)
      2. 8.1.2 Calculating Off-Time
      3. 8.1.3 Setting the Switching Frequency
      4. 8.1.4 Inductor Selection
      5. 8.1.5 Setting the LED Current
      6. 8.1.6 Valley Fill Capacitors
        1. 8.1.6.1 Determining the Capacitance Value of the Valley-Fill Capacitors
        2. 8.1.6.2 Determining Maximum Number of Series Connected LEDs Allowed
      7. 8.1.7 Output Capacitor
      8. 8.1.8 Switching MOSFET
      9. 8.1.9 Re-Circulating Diode
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
  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 Community Resources
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

10 Layout

10.1 Layout Guidelines

Keep the low power components for ASNS, FLTR1, FLTR2, and COFF close to the LM3445 with short traces. The ISNS trace should also be as short and direct as possible. Keep the high current switching paths generated by R3, Q2, L2, and D10 as short as possible to minimize generated switching noise and improve EMI.

10.2 Layout Example

LM3445 snvs570_layout.gif Figure 32. Layout Recommendation