用户手册 — Texas Instruments LM3423 Evaluation Board LM3423BBLSCSEV/NOPB

目录

• Features

  1
• Applications

  1
• Description

  1
  • Typical Boost Application Circuit

    1
  • Connection Diagrams

    2
• Absolute Maximum Ratings

  4
• Operating Conditions

  4
• Electrical Characteristics

  5
• Typical Performance Characteristics

  8
• Block Diagram

  10
• Theory of Operation

  10
  • CURRENT REGULATORS

    11
  • PREDICTIVE OFF-TIME (PRO) CONTROL

    12
  • SWITCHING FREQUENCY

    12
  • AVERAGE LED CURRENT

    13
  • ANALOG DIMMING

    14
  • CURRENT SENSE/CURRENT LIMIT

    15
  • OVER-CURRENT PROTECTION

    16
  • ZERO CURRENT SHUTDOWN

    16
  • CONTROL LOOP COMPENSATION

    16
  • START-UP REGULATOR

    19
  • OVER-VOLTAGE LOCKOUT (OVLO)

    19
  • INPUT UNDER-VOLTAGE LOCKOUT (UVLO)

    20
    • UVLO only

      21
    • PWM dimming and UVLO

      21
  • PWM DIMMING

    21
  • LM3423 ONLY: DPOL, FLT, TIMR, and LRDY

    23
• Design Considerations

  24
  • INDUCTOR

    24
  • LED DYNAMIC RESISTANCE

    25
  • OUTPUT CAPACITOR

    25
  • INPUT CAPACITORS

    25
  • MAIN MosFET / DIMMING MosFET

    26
  • RE-CIRCULATING DIODE

    26
  • BOOST INRUSH CURRENT

    26
  • CIRCUIT LAYOUT

    27
  • Basic Topology Schematics

    28
    • BOOST REGULATOR (VIN < VO)

      28
    • BUCK REGULATOR (VIN > VO)

      29
    • BUCK-BOOST REGULATOR

      30
• Design Guide

  31
  • SPECIFICATIONS

    31
  • 1. OPERATING POINT

    31
  • Buck

    31
  • Boost

    31
  • Buck-boost

    31
  • 2. SWITCHING FREQUENCY

    31
    • Buck (Constant Ripple vs. VIN)

      32
  • Boost and Buck-boost

    32
  • 3. AVERAGE LED CURRENT

    32
  • 4. INDUCTOR RIPPLE CURRENT

    32
    • Buck

      32
    • Boost and Buck-boost

      32
    • Buck

      32
    • Boost and Buck-boost

      33
  • 5. LED RIPPLE CURRENT

    33
    • Buck

      33
    • Boost and Buck-boost

      33
    • Buck

      33
    • Boost and Buck-boost

      33
  • 6. PEAK CURRENT LIMIT

    33
  • 7. LOOP COMPENSATION

    33
    • Buck

      33
    • Boost and Buck-boost

      34
    • Buck

      34
    • Boost

      34
    • Buck-boost

      34
    • Boost

      34
    • Buck-boost

      34
    • Buck

      34
    • Boost

      34
    • Buck-boost

      34
  • 8. INPUT CAPACITANCE

    35
    • Buck

      35
    • Boost

      35
    • Buck-boost

      35
    • Buck

      35
    • Boost

      36
    • Buck-boost

      36
  • 9. NFET

    36
    • Buck

      36
    • Boost

      36
    • Buck-boost

      36
    • Buck

      36
    • Boost and Buck-boost

      36
    • Buck

      36
    • Boost and Buck-boost

      36
  • 10. DIODE

    36
    • Buck

      36
    • Boost

      37
    • Buck-boost

      37
    • Buck

      37
    • Boost and Buck-boost

      37
  • 11. OUTPUT OVLO

    37
    • Boost

      37
    • Buck-boost

      37
  • 12. INPUT UVLO

    37
  • 13. PWM DIMMING METHOD

    38
  • 14. ANALOG DIMMING METHOD

    38
  • Design Example

    39
    • DESIGN #1 - LM3421 BUCK-BOOST Application

      39
    • SPECIFICATIONS

      39
    • 1. OPERATING POINT

      40
    • 2. SWITCHING FREQUENCY

      41
    • 3. AVERAGE LED CURRENT

      41
    • 4. INDUCTOR RIPPLE CURRENT

      41
    • 5. OUTPUT CAPACITANCE

      42
    • 6. PEAK CURRENT LIMIT

      42
    • 7. LOOP COMPENSATION

      42
    • 8. INPUT CAPACITANCE

      43
    • 9. NFET

      43
    • 10. DIODE

      44
    • 11. INPUT UVLO

      44
    • 12. OUTPUT OVLO

      45
    • DESIGN #1 Bill of Materials

      45
• Applications Information

  46
  • DESIGN #2 - LM3421 BOOST Application

    46
  • Features

    46
  • DESIGN #2 Bill of Materials

    47
  • DESIGN #3 - LM3421 BUCK-BOOST Application

    48
  • Features

    48
  • DESIGN #3 Bill of Materials

    49
  • DESIGN #4 - LM3423 BOOST Application

    50
  • Features

    50
  • DESIGN #4 Bill of Materials

    51
  • DESIGN #5 - LM3421 BUCK-BOOST Application

    52
  • Features

    52
  • DESIGN #5 Bill of Materials

    53
  • DESIGN #6 - LM3423 BUCK Application

    54
  • Features

    54
  • DESIGN #6 Bill of Materials

    55
  • DESIGN #7 - LM3423 BUCK-BOOST Application

    56
  • Features

    56
  • DESIGN #7 Bill of Materials

    57
  • DESIGN #8 - LM3421 SEPIC Application

    58
  • Features

    58
  • DESIGN #8 Bill of Materialslayout of National Data Sheet to TI format

    59
• Revision History

  60