TIDUCL3 February   2017

 

  1. 1 Overview
  2. 2 Resources
  3. 3 Features
  4. 4 Applications
  5. 5 Design Images
  6. 6 System Overview
    1. 6.1 System Description
    2. 6.2 Key System Specifications
    3. 6.3 Block Diagram
    4. 6.4 Highlighted Products
      1. 6.4.1 LMT87-Q1
      2. 6.4.2 TLC555-Q1
      3. 6.4.3 OPA2377-Q1
      4. 6.4.4 TL431-Q1
      5. 6.4.5 TPS92691-Q1
  7. 7 System Design Theory
    1. 7.1  PCB and Form Factor
    2. 7.2  Optimizing Board Performance Based on LED String Voltage and Current
    3. 7.3  Switching Frequency
    4. 7.4  Output Overvoltage Protection (OVP)
    5. 7.5  Current Monitoring (IMON)
    6. 7.6  Thermal Foldback
      1. 7.6.1 Changing Thermal Foldback Response
        1. 7.6.1.1 Changing Starting Point for Thermal Foldback
        2. 7.6.1.2 Changing Slope of Thermal Foldback
        3. 7.6.1.3 Constant Current at High Temperatures
      2. 7.6.2 Thermal Foldback Without PWM Dimming
    7. 7.7  Clock Generation (PWM)
    8. 7.8  Onboard Supply and Setting Duty Cycle
    9. 7.9  Buffering, Averaging, and Filtering
    10. 7.10 Boost Converter
  8. 8 Getting Started Hardware
    1. 8.1 Hardware
    2. 8.2 LED Selection
    3. 8.3 J3, LED+, LED– (Boost)
    4. 8.4 J1, POS(+), NEG(–)
    5. 8.5 J4, Temperature Sensor Connection
    6. 8.6 Duty Cycle Adjust
  9. 9 Testing and Results
    1. 9.1 Duty Cycle Accuracy
    2. 9.2 Thermal Foldback Testing
    3. 9.3 EMI Testing
    4. 9.4 Accuracy Calculation
  10. 10Design Files
    1. 10.1 Schematics
    2. 10.2 Bill of Materials
    3. 10.3 PCB Layout Recommendations
      1. 10.3.1 Layout Prints
    4. 10.4 Altium Project
    5. 10.5 Gerber Files
    6. 10.6 Assembly Drawings
  11. 11Related Documentation
    1. 11.1 Trademarks
  12. 12About the Author

8.3 J3, LED+, LED– (Boost)

The screw-down connector (J3, marked LED+ and LED–) is for connecting the LED load to the board in the boost configuration. The leads to the LED load must be twisted and kept as short as possible to minimize voltage drop, inductance, and EMI transmission. The boost design is for approximately 6 to 20 white LEDs.