SNVS653E July   2011  – August 2015 LM3532

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 I2C-Compatible Timing Specifications (SCL, SDA)
    7. 6.7 Switching Characteristics
    8. 6.8 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 40-V Boost Converter
      2. 7.3.2 Hardware Enable Input
      3. 7.3.3 Feedback Enable
      4. 7.3.4 LM3532 Current Sink Configuration
      5. 7.3.5 PWM Inputs
      6. 7.3.6 Full-Scale LED Current
      7. 7.3.7 Interrupt Output
      8. 7.3.8 Protection Features
        1. 7.3.8.1 Overvoltage Protection
        2. 7.3.8.2 Current Limit
    4. 7.4 Device Functional Modes
      1. 7.4.1  LED Current Ramping
      2. 7.4.2  Start-up and Shutdown Current Ramping
      3. 7.4.3  Run-Time Ramp Rates
      4. 7.4.4  LED Current Mapping Modes
      5. 7.4.5  Exponential Current Mapping Mode
      6. 7.4.6  Linear Current Mapping
      7. 7.4.7  LED Current Control
        1. 7.4.7.1 I2C Current Control
        2. 7.4.7.2 I2C Current Control With PWM
      8. 7.4.8  Assigning and Enabling a PWM Input
      9. 7.4.9  Enabling a Current Sink
      10. 7.4.10 Ambient Light Sensor Current Control
        1. 7.4.10.1  ALS Resistors
        2. 7.4.10.2  Ambient Light Zone Boundaries
        3. 7.4.10.3  Ambient Light Zone Hysteresis
        4. 7.4.10.4  PWM Enabled for a Particular Zone
        5. 7.4.10.5  ALS Operation
        6. 7.4.10.6  ALS Input Select and ALS ADC Input
        7. 7.4.10.7  ALS ADC Readback
        8. 7.4.10.8  ALS Averaging
        9. 7.4.10.9  ALS ADC Average Readback
        10. 7.4.10.10 Initializing the ALS
        11. 7.4.10.11 ALS Operation
        12. 7.4.10.12 Direct ALS Control
      11. 7.4.11 Down Delay
    5. 7.5 Programming
      1. 7.5.1 I2C-Compatible Interface
        1. 7.5.1.1 Start and Stop Conditions
        2. 7.5.1.2 I2C-Compatible Address
        3. 7.5.1.3 Transferring Data
    6. 7.6 Register Maps
      1. 7.6.1  Output Configuration
      2. 7.6.2  Start-up/Shutdown Ramp Rate
      3. 7.6.3  Run-Time Ramp Rate
      4. 7.6.4  Control A PWM
      5. 7.6.5  Control B PWM
      6. 7.6.6  Control C PWM
      7. 7.6.7  Control A Brightness Configuration
      8. 7.6.8  Control B Brightness Configuration
      9. 7.6.9  Control C Brightness Configuration
      10. 7.6.10 Control A, B, and C Full-Scale Current
      11. 7.6.11 Feedback Enable
      12. 7.6.12 Control Enable
      13. 7.6.13 ALS1 and ALS2 Resistor Select
      14. 7.6.14 ALS Down Delay
      15. 7.6.15 ALS Configuration
      16. 7.6.16 ALS Zone Readback / Information
      17. 7.6.17 ALS Zone Boundaries
      18. 7.6.18 Zone Target Registers
  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 Inductor Selection
        2. 8.2.2.2 Capacitor Selection
        3. 8.2.2.3 Diode Selection
        4. 8.2.2.4 Maximum Output Power
          1. 8.2.2.4.1 Peak Current Limited
          2. 8.2.2.4.2 Output Voltage Limited
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Output Capacitor Placement
      2. 10.1.2 Schottky Diode Placement
      3. 10.1.3 Inductor Placement
      4. 10.1.4 Input Capacitor Selection and Placement
    2. 10.2 Layout Examples
  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 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

1 Features

  • Drives up to 3 Parallel High-Voltage LED Strings at 40 V Each With up to 90% Efficiency
  • 0.4% Typical Current Matching Between Strings
  • 256 Level Logarithmic and Linear Brightness Control With 14-Bit Equivalent Dimming
  • I2C-Compatible Interface
  • Direct Read Back of Ambient Light Sensor Via
    8-bit ADC
  • Programmable Dual Ambient Light Sensor Inputs With Internal Sensor Gain Selection
  • Dual External PWM Inputs for LED Brightness Adjustment
  • Independent Current String Brightness Control
  • Programmable LED Current Ramp Rates
  • 40-V Overvoltage Protection
  • 1-A Typical Current Limit

2 Applications

  • Power Source for White LED Backlit LCD Displays
  • Programmable Keypad Backlight

3 Description

The LM3532 is a 500-kHz fixed frequency asynchronous boost converter which provides the power for 3 high-voltage, low-side current sinks. The device is programmable over an I2C-compatible interface and has independent current control for all three channels. The adaptive current regulation method allows for different LED currents in each current sink thus allowing for a wide variety of backlight and keypad applications.

The main features of the LM3532 include dual ambient light sensor inputs each with 32 internal voltage setting resistors, 8-bit logarithmic and linear brightness control, dual external PWM brightness control inputs, and up to 1000:1 dimming ratio with programmable fade in and fade out settings.

The LM3532 is available in a 16-pin, 0.4-mm pitch thin DSBGA package. The device operates over a 2.7-V to 5.5-V input voltage range and the −40°C to +85°C temperature range.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (MAX)
LM3532 DSBGA (16) 1.87 mm x 1.77 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application Circuit

LM3532 301154100.gif