用户手册 — Texas Instruments LM3409 Demonstration Board LM3409EVAL/NOPB

目录

• Features

  1
• Applications

  1
• Description

  1
  • Typical Application

    1
  • Connection Diagram

    2
• Absolute Maximum RatingsLM3409/09N/09Q/09HV/09QHV

  3
• Operating Ratings (LM3409/09N/09Q/09HV/09QHV)

  3
• Electrical Characteristics LM3409/09N/09Q/09HV/09QHV

  3
• Typical Performance Characteristics

  5
• Block Diagram

  8
• Theory of Operation

  8
  • BUCK CURRENT REGULATORS

    8
  • CONTROLLED OFF-TIME (COFT) ARCHITECTURE

    9
    • Adjustable Peak Current Control

      9
    • Controlled Off-Time

      10
  • AVERAGE LED CURRENT

    12
  • INDUCTOR CURRENT RIPPLE

    13
  • SWITCHING FREQUENCY

    13
  • PWM DIMMING USING THE EN PIN

    14
  • HIGH VOLTAGE NEGATIVE BIAS REGULATOR

    14
  • INPUT UNDER-VOLTAGE LOCKOUT (UVLO)

    14
  • LOW POWER SHUTDOWN

    15
  • THERMAL SHUTDOWN

    15
• Design Considerations

  15
  • OPERATION NEAR DROPOUT

    15
  • LED RIPPLE CURRENT

    15
  • BUCK CONVERTERS W/O OUTPUT CAPACITORS

    16
  • BUCK CONVERTERS WITH OUTPUT CAPACITORS

    16
  • OUTPUT OVER-VOLTAGE PROTECTION

    17
  • INPUT CAPACITORS

    17
  • P-CHANNEL MosFET (PFET)

    17
  • RE-CIRCULATING DIODE

    18
  • EXTERNAL PARALLEL FET PWM DIMMING

    18
  • CIRCUIT LAYOUT

    19
• Design Guide

  20
  • TYPICAL APPLICATION

    20
  • SPECIFICATIONS

    20
  • 1. NOMINAL SWITCHING FREQUENCY

    20
  • 2. INDUCTOR RIPPLE CURRENT

    21
  • 3. AVERAGE LED CURRENT

    21
  • 4. OUTPUT CAPACITANCE

    21
  • 5. INPUT CAPACITANCE

    21
  • 6. PFET

    22
  • 7. DIODE

    22
  • 8. INPUT UVLO

    22
  • 9. IADJ CONNECTION METHOD

    22
  • 10. PWM DIMMING METHOD

    23
  • Design Example #1

    23
    • EN PIN PWM DIMMING APPLICATION FOR 10 LEDS

      23
    • SPECIFICATIONS

      23
    • 1. NOMINAL SWITCHING FREQUENCY

      23
    • 2. INDUCTOR RIPPLE CURRENT

      24
    • 3. AVERAGE LED CURRENT

      24
    • 4. OUTPUT CAPACITANCE

      25
    • 5. INPUT CAPACITANCE

      25
    • 6. PFET

      25
    • 7. DIODE

      26
    • 8. INPUT UVLO

      26
    • 9. IADJ CONNECTION METHOD

      26
    • 10. PWM DIMMING METHOD

      26
    • Design #1 Bill of Materials

      27
  • Design Example #2

    27
    • ANALOG DIMMING APPLICATION FOR 4 LEDS

      27
    • SPECIFICATIONS

      27
    • 1. NOMINAL SWITCHING FREQUENCY

      28
    • 2. INDUCTOR RIPPLE CURRENT

      28
    • 3. AVERAGE LED CURRENT

      28
    • 4. OUTPUT CAPACITANCE

      29
    • 5. INPUT CAPACITANCE

      29
    • 6. PFET

      30
    • 7. DIODE

      30
    • 8. INPUT UVLO

      30
    • 9. IADJ CONNECTION METHOD

      31
    • 10. PWM DIMMING METHOD

      31
    • Design #2 Bill of Materials

      31
• Applications Information

  32
  • DESIGN #3: EXTERNAL PARALLEL FET PWM DIMMING APPLICATION FOR 10 LEDS

    32
  • Design #3 Bill of Materials

    32
  • DESIGN #4: SINGLE POTENTIOMETER ANALOG DIMMING APPLICATION FOR 6 LEDS

    33
  • Design #4 Bill of Materials

    33
  • DESIGN #5: 75°C THERMAL FOLDBACK APPLICATION FOR 16 LEDS

    34
  • Design #5 Bill of Materials

    34
  • DESIGN #6: HIGH CURRENT APPLICATION FOR 4 LEDS

    35
  • Design #6 Bill of Materialslayout of National Data Sheet to TI format

    35
• Revision History

  36