SNVS821A January   2014  – March 2014 LM3699

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Terminal Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Handling 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 PWM Input
        1. 7.3.1.1 PWM Input Frequency Range
        2. 7.3.1.2 PWM Low Detect
      2. 7.3.2 HWEN Input
      3. 7.3.3 Current Select Inputs (IS1 And IS0)
      4. 7.3.4 ILOW Input
      5. 7.3.5 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation with an Unused Current Sink
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Step-by-Step Design Procedure
        2. 8.2.2.2 Maximum Output Power
          1. 8.2.2.2.1 Peak Current Limited
          2. 8.2.2.2.2 Output Voltage Limited
        3. 8.2.2.3 Boost Inductor Selection
        4. 8.2.2.4 Output Capacitor Selection
        5. 8.2.2.5 Schottky Diode Selection
        6. 8.2.2.6 Input Capacitor Selection
      3. 8.2.3 Application Performance Plots
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Boost Output Capacitor Placement
      2. 10.1.2 Schottky Diode Placement
      3. 10.1.3 Inductor Placement
      4. 10.1.4 Boost Input Capacitor Placement
    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 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

1 Features

  • Drives Parallel High-Voltage LED Strings for Display or Keypad Lighting
  • Boost Converter up to 90% Efficiency
  • Four User-Selectable Full-Scale Current Settings
    (20.2 mA, 18.6 mA, 17.0 mA, 15.4 mA)
  • Quick-Dimming Enable Terminal (ILOW)
  • Simple PWM Duty Cycle Control
  • 24-V Overvoltage Protection Threshold
  • Fixed 1-MHz Switching Frequency
  • Integrated 1-A/40-V MOSFET
  • Three Current Sink Terminals
  • Adaptive Boost Output to LED Voltages
  • Thermal Shutdown Protection
  • 29-mm2 Total Solution Size

2 Applications

  • Power Source for Smart Phone Illumination
  • Display or Keypad Illumination

3 Description

The LM3699 is a three-string, high-efficiency, PWM-controlled power source for display backlight or keypad LEDs in smartphone handsets. The high-voltage inductive boost converter with integrated 1-A, 40-V MOSFET provides the power for three series LED strings. The boost output automatically adjusts to LED forward voltage to minimize headroom voltage and effectively improve LED efficiency.

The ILOW terminal provides a method to quickly reduce LED brightness during camera flash operation.

The LM3699 has integrated overvoltage, overcurrent, and thermal protection.

The device operates over a 2.7-V to 5.5-V input voltage range and a −40°C to 85°C temperature range.

Device Information

ORDER NUMBER PACKAGE BODY SIZE
LM3699YFQ DSBGA (12) 1,64 mm x 1,29 mm

 
Simplified Schematic

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