SNVSA63A April   2015  – September 2015 LM3632A

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 Timing Requirements (SDA, SCL)
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Features Description
      1. 7.3.1 Backlight
        1. 7.3.1.1 Brightness Control
          1. 7.3.1.1.1 LED Current with PWM Disabled
          2. 7.3.1.1.2 LED Current with PWM Enabled
        2. 7.3.1.2 Sloper
        3. 7.3.1.3 Mapper
        4. 7.3.1.4 PWM Input
        5. 7.3.1.5 PWM Minimum On/Off Time
        6. 7.3.1.6 PWM Resolution and Input Frequency Range
        7. 7.3.1.7 PWM Hysteresis
        8. 7.3.1.8 PWM Timeout
        9. 7.3.1.9 Backlight Boost Converter
          1. 7.3.1.9.1 Headroom Voltage
          2. 7.3.1.9.2 Backlight Protection and Faults
            1. 7.3.1.9.2.1 Overvoltage Protection (OVP) and Open-Load Fault Protection
            2. 7.3.1.9.2.2 Overcurrent Protection (OCP) and Overcurrent Protection Flag
      2. 7.3.2 LCM Bias
        1. 7.3.2.1 Display Bias Boost Converter (VVPOS, VVNEG)
        2. 7.3.2.2 Auto Sequence Mode
        3. 7.3.2.3 Wake-up Mode
        4. 7.3.2.4 Active Discharge
        5. 7.3.2.5 LCM Bias Protection and Faults
          1. 7.3.2.5.1 LCM Overvoltage Protection
          2. 7.3.2.5.2 VNEG Overvoltage Protection
          3. 7.3.2.5.3 VPOS Short Circuit Protection
          4. 7.3.2.5.4 VNEG Short Circuit Protection
      3. 7.3.3 Flash
        1. 7.3.3.1 Flash Boost Converter
        2. 7.3.3.2 Start-Up (Enabling The Device)
        3. 7.3.3.3 Pass Mode
        4. 7.3.3.4 Flash Mode
        5. 7.3.3.5 Torch Mode
        6. 7.3.3.6 Power Amplifier Synchronization (TX)
        7. 7.3.3.7 VIN Monitor
        8. 7.3.3.8 Flash Fault Protections
          1. 7.3.3.8.1 Fault Operation
          2. 7.3.3.8.2 Flash Time-Out
          3. 7.3.3.8.3 Overvoltage Protection (OVP)
          4. 7.3.3.8.4 Current Limit
          5. 7.3.3.8.5 FLED and/or FL_OUT Short Fault
      4. 7.3.4 Software RESET
      5. 7.3.5 EN Input
      6. 7.3.6 Thermal Shutdown (TSD)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Modes of Operation
    5. 7.5 Programming
      1. 7.5.1 I2C-Compatible Serial Bus Interface
        1. 7.5.1.1 Interface Bus Overview
        2. 7.5.1.2 Data Transactions
        3. 7.5.1.3 Acknowledge Cycle
        4. 7.5.1.4 Acknowledge After Every Byte Rule
        5. 7.5.1.5 Addressing Transfer Formats
    6. 7.6 Register Maps
      1. 7.6.1  Revision (Address = 0x01) [reset = 0x09]
      2. 7.6.2  Backlight Configuration1 (Address = 0x02) [reset = 0x30]
      3. 7.6.3  Backlight Configuration2 (Address = 0x03) [reset = 0x0D]
      4. 7.6.4  Backlight Brightness LSB (Address = 0x04) [reset = 0x07]
      5. 7.6.5  Backlight Brightness MSB (Address = 0x05) [reset = 0xFF]
      6. 7.6.6  Flash/Torch Current (Address = 0x06) [reset = 0x3E]
      7. 7.6.7  Flash Configuration (Address = 0x07) [reset = 0x2F]
      8. 7.6.8  VIN Monitor (Address = 0x08) [reset = 0x03]
      9. 7.6.9  I/O Control (Address = 0x09) [reset = 0x00]
      10. 7.6.10 Enable (Address = 0x0A) [reset = 0x00]
      11. 7.6.11 Flags1 (Address = 0x0B) [reset = 0x00]
      12. 7.6.12 Display Bias Configuration (Address = 0x0C) [reset = 0x18]
      13. 7.6.13 LCM Boost Bias (Address = 0x0D) [reset = 0x1E]
      14. 7.6.14 VPOS Bias (Address = 0x0E) [reset = 0x1E]
      15. 7.6.15 VNEG Bias (Address = 0x0F) [reset = 0x1C]
      16. 7.6.16 Flags2 (Address = 0x10) [reset = 0x00]
  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 External Components
        2. 8.2.2.2 Inductor Selection
        3. 8.2.2.3 Boost Output Capacitor Selection
        4. 8.2.2.4 Input Capacitor Selection
      3. 8.2.3 Application Curves
        1. 8.2.3.1 Backlight Curves
        2. 8.2.3.2 LCM Bias Curves
        3. 8.2.3.3 Flash Curves
  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 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 Two Strings of Typically Eight LEDs in Series
    • Integrated Backlight Boost with 29-V Maximum Output Voltage
    • Two Low-Side Constant-Current LED Drivers with 25-mA Maximum Output Current
  • Backlight Efficiency Up to 90%
  • 11-Bit Exponential or Linear Dimming
  • External PWM Input for CABC Backlight Operation
  • LCD Bias Efficiency > 85%
  • Programmable Positive LCD bias, 4-V to 6-V, 50-mA Maximum Output Current
  • Programmable Negative LCD bias, –4-V to –6-V, 50-mA Maximum Output Current
  • 1.5-A Flash LED Boost
  • Flash Efficiency > 85%
  • 2.7-V to 5-V Input Voltage Range

2 Applications

  • Smart Phone LCD Backlighting and Bias
  • Small Tablet LCD Backlighting and Bias

3 Description

The LM3632A integrates the WLED drivers for both the backlight of the LCD panel and the camera flash along with the bias power for the LCD panel into one device. The device has all the safety features required in LED drivers with up to 90% efficiency and bias positive/negative power rails achieving 1.5% accuracy. Capable of driving up to 16 backlight LEDs, the device is ideal for small- to medium-size displays. A 1.5-A constant-current LED driver powered by a synchronous boost converter can be used for flash applications. The high-side flash current source allows for grounded cathode LED operation.

A high level of integration and programmability allows the LM3632A to address a variety of applications without the need for hardware changes.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (MAX)
LM3632A DSBGA (30) 2.47 mm x 2.07 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

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Simplified Schematic

LM3632A LM3632_smpl_sch.gif

Backlight Efficiency, 2P7S

LM3632A D007_SNVSA63.gif