ZHCSCC4D November   2013  – March 2019 LM3697

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
  3. 3 说明
    1.     Device Images
      1.      简化原理图
      2.      升压效率
  4. 4 修订历史记录
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Timing Requirements
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
      1. 7.1.1 PWM Input
      2. 7.1.2 HWEN Input
      3. 7.1.3 Thermal Shutdown
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Descriptions
      1. 7.3.1 High-Voltage LED Control
        1. 7.3.1.1 High-Voltage Boost Converter
        2. 7.3.1.2 High-Voltage Current Sinks (HVLED1, HVLED2 and HVLED3)
        3. 7.3.1.3 High-Voltage Current String Biasing
      2. 7.3.2 Boost Switching-Frequency Select
      3. 7.3.3 Automatic Switching Frequency Shift
      4. 7.3.4 Brightness Register Current Control
        1. 7.3.4.1 8-Bit Control (Preferred)
        2. 7.3.4.2 11-Bit Control
      5. 7.3.5 PWM Control
        1. 7.3.5.1 PWM Input Frequency Range
        2. 7.3.5.2 PWM Input Polarity
        3. 7.3.5.3 PWM Zero Detection
      6. 7.3.6 Start-up/Shutdown Ramp
      7. 7.3.7 Run-Time Ramp
      8. 7.3.8 High-Voltage Control A and B Ramp Select
    4. 7.4 Device Functional Modes
      1. 7.4.1 LED Current Mapping Modes
        1. 7.4.1.1 Exponential Mapping
          1. 7.4.1.1.1 8-Bit Code Calculation
          2. 7.4.1.1.2 11-Bit Code Calculation
        2. 7.4.1.2 Linear Mapping
          1. 7.4.1.2.1 8-Bit Code Calculation
          2. 7.4.1.2.2 11-Bit Code Calculation
      2. 7.4.2 Fault Flags/Protection Features
        1. 7.4.2.1 Open LED String (HVLED)
        2. 7.4.2.2 Shorted LED String (HVLED)
        3. 7.4.2.3 Overvoltage Protection (Inductive Boost)
        4. 7.4.2.4 Current Limit (Inductive Boost)
      3. 7.4.3 I2C-Compatible Interface
        1. 7.4.3.1 Start And Stop Conditions
        2. 7.4.3.2 I2C-Compatible Address
        3. 7.4.3.3 Transferring Data
        4. 7.4.3.4 High-Speed Mode
    5. 7.5 Register Maps
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Boost Converter Maximum Output Power
          1. 8.2.2.1.1 Peak Current Limited
          2. 8.2.2.1.2 Output Voltage Limited
        2. 8.2.2.2 Inductor Selection
        3. 8.2.2.3 Output Capacitor Selection
        4. 8.2.2.4 Schottky Diode Selection
        5. 8.2.2.5 Input Capacitor Selection
        6. 8.2.2.6 Application Circuit Component List
      3. 8.2.3 Application Performance Plots
    3. 8.3 Initialization Set Up
  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. 11器件和文档支持
    1. 11.1 器件支持
      1. 11.1.1 第三方产品免责声明
    2. 11.2 相关文档　
    3. 11.3 接收文档更新通知
    4. 11.4 社区资源
    5. 11.5 商标
    6. 11.6 静电放电警告
    7. 11.7 术语表
  12. 12机械、封装和可订购信息

封装选项

请参考 PDF 数据表获取器件具体的封装图。

机械数据 (封装 | 引脚)
  • YFQ|12
散热焊盘机械数据 (封装 | 引脚)
订购信息

7.3.1.3 High-Voltage Current String Biasing

Each high-voltage current string can be powered from the LM3697’s boost output (COUT) or from an external source. The feedback enable bits (HVLED Current Sink Feedback Enables register bits [2:0]) determine where the high-voltage current string anodes connect. When set to '1' (default) the high-voltage current sink inputs are included in the boost feedback loop. This allows the boost converter to adjust its output voltage in order to maintain the LED headroom voltage VHR_MIN at the current sink input.

When powered from alternate sources the feedback enable bits must be set to '0'. This removes the particular current sink from the boost feedback loop. In these configurations the application must ensure that the headroom voltage across the high-voltage current sink is high enough to prevent the current sink from going into dropout (see the Typical Characteristics for data on the high-voltage LED current vs VHR_MIN).

Setting the HVLED Current Sink Feedback Enables register bits also determines triggering of the shorted high-voltage LED String Fault flag (see the Fault Flags/Protection Features section).