Benutzerhandbuch für Texas Instruments LM3448 Evaluation Board LM3448-EDSNEV/NOPB

Inhaltsverzeichnis

• FEATURES

  1
• APPLICATIONS

  1
• DESCRIPTION

  1
  • Typical LM3448 LED Driver Application Circuit

    1
  • Connection Diagram

    2
• ABSOLUTE MAXIMUM RATINGS

  3
• OPERATING CONDITIONS

  3
• ELECTRICAL CHARACTERISTICS

  4
• TYPICAL PERFORMANCE CHARACTERISTICS

  6
• SIMPLIFIED INTERNAL BLOCK DIAGRAM

  8
• THEORY OF OPERATION

  8
  • OVERVIEW OF PHASE CONTROL DIMMING

    8
  • SENSING THE RECTIFIED TRIAC WAVEFORM

    10
  • ANGLE DETECT

    11
  • BLEEDER

    12
  • FLTR1 PIN

    12
  • DIM DECODER

    12
  • FLTR2

    12
  • COFF AND CONSTANT OFF-TIME CONTROL OVERVIEW

    12
  • VCC BIAS SUPPLY

    14
  • THERMAL SHUTDOWN

    14
  • Design Considerations

    14
    • VALLEY-FILL POWER FACTOR CORRECTION

      14
    • FLTR2 LINE-INJECTION

      16
    • DIRECT LINE-INJECTION FOR FLYBACK TOPOLOGY

      16
    • TRIAC DIMMER HOLDING CURRENT

      17
    • OPTIMIZING THE HOLDING CURRENT

      18
    • Linear Hold Insertion Circuit

      19
    • Valley-Fill Holding Current Circuit

      19
    • TRIAC Edge Detect Circuit

      19
    • Forward Phase Holding Current Circuit

      19
    • Reverse Phase Holding Current Circuit

      19
    • START-UP AND BIAS SUPPLY

      19
    • COFF CURRENT SOURCE CIRCUITS

      21
  • Design Guide

    23
    • DETERMINING DUTY-CYCLE (D)

      23
    • CALCULATING OFF-TIME

      24
    • SETTING THE SWITCHING FREQUENCY

      24
    • INDUCTOR SELECTION

      25
    • SETTING THE LED CURRENT

      26
    • CURRENT LIMIT

      27
    • VALLEY FILL CAPACITORS

      27
    • MAXIMUM NUMBER OF SERIES CONNECTED LEDS

      28
    • OUTPUT CAPACITOR

      30
    • RE-CIRCULATING DIODE

      30
  • Design Calculation Example

    30
    • SPECIFICATIONS

      30
    • CHOSEN VALUES

      30
    • CALCULATIONS

      30
• APPLICATIONS INFORMATION

  32
  • DESIGN #1: 7W, 120VAC Non-isolated Buck LED Driver with Valley-Fill PFC

    32
  • DESIGN #2: 6.5W, 120VAC Non-isolated “A19 Edison” Retrofit with AC-Coupled Line Injection

    35
  • DESIGN #3: 6W, 120VAC Isolated Flyback LED Driver with Direct Line Injection

    36
  • DESIGN #4: 6W, 230VAC Isolated Flyback LED Driver with Direct Line Injection

    38
• REVISION HISTORY

  40