Benutzerhandbuch für Texas Instruments LM3429 Evaluation Boards LM3429BKBSTEVAL/NOPB

Inhaltsverzeichnis

• Features

  1
• Applications

  1
• Description

  1
  • Typical Boost Application Circuit

    1
  • Connection Diagram

    2
• Absolute Maximum Ratings

  3
• Operating Conditions

  3
• Electrical Characteristics

  4
• Typical Performance Characteristics

  6
• Block Diagram

  8
• Theory of Operation

  8
  • CURRENT REGULATORS

    9
    • Buck

      9
    • Boost

      9
    • Buck-boost

      9
  • PREDICTIVE OFF-TIME (PRO) CONTROL

    9
  • SWITCHING FREQUENCY

    10
    • Buck (Constant Ripple vs. VIN)

      11
    • Buck (Constant Ripple vs. VO)

      11
    • Boost and Buck-boost

      11
  • AVERAGE LED CURRENT

    11
  • ANALOG DIMMING

    12
  • CURRENT SENSE/CURRENT LIMIT

    13
  • CONTROL LOOP COMPENSATION

    14
  • OUTPUT OVER-VOLTAGE LOCKOUT (OVLO)

    16
    • Ground Referenced

      17
    • Floating

      17
  • INPUT UNDER-VOLTAGE LOCKOUT (UVLO)

    17
    • UVLO only

      18
    • PWM dimming and UVLO

      18
  • PWM DIMMING

    18
  • STARTUP REGULATOR (VCC LDO)

    19
  • THERMAL SHUTDOWN

    19
• Design Considerations

  19
  • INDUCTOR

    19
  • LED DYNAMIC RESISTANCE (rD)

    20
  • OUTPUT CAPACITOR

    20
  • INPUT CAPACITORS

    20
  • N-CHANNEL MosFET (NFET)

    21
  • RE-CIRCULATING DIODE

    21
  • CIRCUIT LAYOUT

    21
  • Basic Topology Schematics

    22
    • BOOST REGULATOR (VIN < VO)

      22
    • BUCK REGULATOR (VIN > VO)

      23
    • BUCK-BOOST REGULATOR

      23
  • Design Guide

    24
    • SPECIFICATIONS

      24
    • 1. OPERATING POINT

      24
    • 2. SWITCHING FREQUENCY

      24
    • 3. AVERAGE LED CURRENT

      25
    • 4. INDUCTOR RIPPLE CURRENT

      25
    • 5. LED RIPPLE CURRENT

      26
    • 6. PEAK CURRENT LIMIT

      26
    • 7. LOOP COMPENSATION

      26
    • 8. INPUT CAPACITANCE

      28
    • 9. NFET

      29
    • 10. DIODE

      29
    • 11. OUTPUT OVLO

      30
    • 12. INPUT UVLO

      30
    • 13. PWM DIMMING METHOD

      31
    • 14. ANALOG DIMMING METHOD

      31
  • Design Example #1

    31
    • BUCK-BOOST APPLICATION - 6 LEDs at 1A

      31
    • SPECIFICATIONS

      32
    • 1. OPERATING POINT

      32
    • 2. SWITCHING FREQUENCY

      32
    • 3. AVERAGE LED CURRENT

      33
    • 4. INDUCTOR RIPPLE CURRENT

      33
    • 5. OUTPUT CAPACITANCE

      33
    • 6. PEAK CURRENT LIMIT

      34
    • 7. LOOP COMPENSATION

      34
    • 8. INPUT CAPACITANCE

      35
    • 9. NFET

      35
    • 10. DIODE

      36
    • 11. INPUT UVLO

      36
    • 12. OUTPUT OVLO

      36
    • Design #1 Bill of Materials

      37
• Applications Information

  38
  • DESIGN #2: BOOST PWM DIMMING APPLICATION - 9 LEDs at 1A

    38
  • Design #2 Bill of Materials

    38
  • DESIGN #3: BUCK-BOOST ANALOG DIMMING APPLICATION - 4 LEDs at 2A

    39
  • Design #3 Bill of Materials

    39
  • DESIGN #4: BOOST ANALOG DIMMING APPLICATION - 12 LEDs at 700mA

    40
  • Design #4 Bill of Materials

    40
  • DESIGN #5: BUCK-BOOST PWM DIMMING APPLICATION - 6 LEDs at 500mA

    41
  • Design #5 Bill of Materials

    41
  • DESIGN #6: BUCK APPLICATION - 3 LEDS AT 1.25A

    42
  • Design #6 Bill of Materials

    42
  • DESIGN #7: BUCK-BOOST THERMAL FOLDBACK APPLICATION - 8 LEDs at 2.5A

    43
  • Design #7 Bill of Materials

    43
  • DESIGN #8: SEPIC APPLICATION - 5 LEDs at 750mA

    44
  • Design #8 Bill of Materialslayout of National Data Sheet to TI format

    44
• Revision History

  45