SNVS682D November   2010  – December 2015 LM3444

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Theory of Operation
      2. 7.3.2 Valley-Fill Circuit
      3. 7.3.3 Valley-Fill Operation
      4. 7.3.4 Buck Converter
      5. 7.3.5 Overview Of Constant Off-Time Control
      6. 7.3.6 Thermal Shutdown
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Determining Duty-Cycle (D)
      2. 8.1.2  Calculating Off-Time
      3. 8.1.3  Setting the Switching Frequency
      4. 8.1.4  Inductor Selection
      5. 8.1.5  Setting the LED Current
      6. 8.1.6  Valley Fill Capacitors
      7. 8.1.7  Determining the Capacitance Value of the Valley-Fill Capacitors
      8. 8.1.8  Determining Maximum Number of Series Connected LEDs Allowed
      9. 8.1.9  Output Capacitor
      10. 8.1.10 Switching MOSFET
      11. 8.1.11 Recirculating Diode
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary

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订购信息

1 Features

  • Application Voltage Range: 80 VAC to 277 VAC
  • Capable of Controlling LED Currents
    Greater than 1 A
  • Adjustable Switching Frequency
  • Low Quiescent Current
  • Adaptive Programmable Off-Time Allows for Constant Ripple Current
  • Thermal Shutdown
  • No Flicker at 120 Hz
  • Low-Profile 10-Pin VSSOP Package
    or 8-Lead SOIC Package
  • Patented Drive Architecture

2 Applications

  • Solid State Lighting
  • Industrial and Commercial Lighting
  • Residential Lighting

    • SPACE

3 Description

The LM3444 is an adaptive constant off-time AC/DC buck (step-down) constant current controller that provides a constant current for illuminating high power LEDs. The high-frequency capable architecture allows the use of small external passive components. A passive PFC circuit ensures good power factor by drawing current directly from the line for most of the cycle, and provides a constant positive voltage to the buck regulator. Additional features include thermal shutdown, current limit and VCC undervoltage lockout. The LM3444 is available in a low profile 10-pin VSSOP package or an 8-lead SOIC package.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM3444 VSSOP (10) 3.00 mm × 3.00 mm
SOIC (8) 3.91 mm × 4.90 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical LM3444 LED Driver Application Circuit

LM3444 30127501.gif

Efficiency vs Line Voltage

LM3444 30127505.gif