SNVS616H April   2009  – July 2015 LM3429 , LM3429-Q1

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  Current Regulators
      2. 7.3.2  Predictive Off-Time (PRO) Control
      3. 7.3.3  Switching Frequency
      4. 7.3.4  Average LED Current
      5. 7.3.5  Analog Dimming
      6. 7.3.6  Current Sense and Current Limit
      7. 7.3.7  Control Loop Compensation
      8. 7.3.8  Output Overvoltage Lockout (OVLO)
      9. 7.3.9  Input Undervoltage Lockout (UVLO)
      10. 7.3.10 PWM Dimming
      11. 7.3.11 Startup Regulator (VCC LDO)
      12. 7.3.12 Thermal Shutdown
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Inductor
      2. 8.1.2 LED Dynamic Resistance (rD)
      3. 8.1.3 Output Capacitor
      4. 8.1.4 Input Capacitors
      5. 8.1.5 N-Channel MosFET (NFET)
      6. 8.1.6 Re-Circulating Diode
    2. 8.2 Typical Applications
      1. 8.2.1 Basic Topology Schematics
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1  Operating Point
          2. 8.2.1.2.2  Switching Frequency
          3. 8.2.1.2.3  Average LED Current
          4. 8.2.1.2.4  Inductor Ripple Current
          5. 8.2.1.2.5  LED Ripple Current
          6. 8.2.1.2.6  Peak Current Limit
          7. 8.2.1.2.7  Loop Compensation
          8. 8.2.1.2.8  Input Capacitance
          9. 8.2.1.2.9  NFET
          10. 8.2.1.2.10 Diode
          11. 8.2.1.2.11 Output OVLO
          12. 8.2.1.2.12 Input UVLO
          13. 8.2.1.2.13 PWM Dimming Method
          14. 8.2.1.2.14 Analog Dimming Method
      2. 8.2.2 Buck-Boost Application - 6 LEDs at 1 A
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1  Operating Point
          2. 8.2.2.2.2  Switching Frequency
          3. 8.2.2.2.3  Average LED Current
          4. 8.2.2.2.4  Inductor Ripple Current
          5. 8.2.2.2.5  Output Capacitance
          6. 8.2.2.2.6  Peak Current Limit
          7. 8.2.2.2.7  Loop Compensation
          8. 8.2.2.2.8  Input Capacitance
          9. 8.2.2.2.9  NFET
          10. 8.2.2.2.10 Diode
          11. 8.2.2.2.11 Input UVLO
          12. 8.2.2.2.12 Output OVLO
        3. 8.2.2.3 Application Curve
      3. 8.2.3 Boost PWM Dimming Application - 9 LEDs at 1 A
        1. 8.2.3.1 Detailed Design Procedure
      4. 8.2.4 Buck-Boost Analog Dimming Application - 4 LEDs at 2A
        1. 8.2.4.1 Detailed Design Procedure
      5. 8.2.5 Boost Analog Dimming Application - 12 LEDs at 700 mA
        1. 8.2.5.1 Detailed Design Procedure
      6. 8.2.6 Buck-Boost PWM Dimming Application - 6 LEDs at 500 mA
        1. 8.2.6.1 Detailed Design Procedure
      7. 8.2.7 Buck Application - 3 LEDS at 1.25 A
        1. 8.2.7.1 Detailed Design Procedure
      8. 8.2.8 Buck-Boost Thermal Foldback Application - 8 LEDs at 2.5 A
        1. 8.2.8.1 Detailed Design Procedure
      9. 8.2.9 SEPIC Application - 5 LEDs at 750 mA
        1. 8.2.9.1 Detailed Design Procedure
  9. 9 Power Supply Recommendations
    1. 9.1 Input Supply Current Limit
  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 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Related Links
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

1 Features

  • LM3429-Q1 is AEC-Q100 Grade 1 Qualified for Automotive Applications
  • VIN Range From 4.5 V to 75 V
  • Adjustable Current Sense Voltage
  • High-Side Current Sensing
  • 2-Ω, 1-A Peak MosFET Gate Driver
  • Input Undervoltage Protection
  • Overvoltage Protection
  • PWM Dimming
  • Analog Dimming
  • Cycle-by-Cycle Current Limit
  • Programmable Switching Frequency
  • Low Profile 14-lead HTSSOP Package
  • Thermal Shutdown

2 Applications

  • LED Drivers - Buck, Boost, Buck-Boost, SEPIC
  • Indoor and Outdoor SSL
  • Automotive
  • General Illumination
  • Constant-Current Regulators

3 Description

The LM3429 is a versatile high voltage N-channel MosFET controller for LED drivers. It can be easily configured in buck, boost, buck-boost and SEPIC topologies. This flexibility, along with an input voltage rating of 75V, makes the LM3429 ideal for illuminating LEDs in a very diverse, large family of applications.

Adjustable high-side current sense voltage allows for tight regulation of the LED current with the highest efficiency possible. The LM3429 uses Predictive Off-time (PRO) control, which is a combination of peak current-mode control and a predictive off-timer. This method of control eases the design of loop compensation while providing inherent input voltage feed-forward compensation.

The LM3429 includes a high-voltage startup regulator that operates over a wide input range of 4.5 V to 75 V. The internal PWM controller is designed for adjustable switching frequencies of up to 2 MHz, thus enabling compact solutions. Additional features include analog dimming, PWM dimming, overvoltage protection, undervoltage lock-out, cycle-by-cycle current limit, and thermal shutdown.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM3429 HTSSOP (14) 5.00 mm × 4.40 mm
LM3429-Q1
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Boost Application Circuit

LM3429 LM3429-Q1 300944i9.gif