SNOAA69 April   2021 LM36922 , LM36923 , LM3697

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 LM3697 Key Specifications
    2. 1.2 LM3697 Simplified Block Diagram
  3. 2How to map Exponential Data to the Linear Dimming Lookup Table
    1. 2.1 Why use Exponential Data for Dimming?
    2. 2.2 Design Sample: Map Exponential Data to Linear Brightness Dimming Lookup Table
  4. 3Key LM369xx Design Tips
    1. 3.1 Simplified Schematic
    2. 3.2 How to Choose Key Components: Inductor and Capacitor, Schottky Diode D1
  5. 4LM369xx PCB Layout Tips
  6. 5References

1.1 LM3697 Key Specifications

The following features are available with the LM3697 device:

  • 2.7-V to 5.5-V input voltage range
  • Drives up to three parallel white LED strings (40-V maximum VOUT)
  • Backlight efficiency up to 90%
  • Up to 30 mA per current sink
  • 11-bit exponential and linear dimming control via PWM, or I2C brightness control, or both
  • Supports CABC function
  • Backlight operation with 4.7-µH to 22-µH inductor
  • Selectable 500-kHz and 1-MHz switching frequency
  • Four configurable overvoltage protection thresholds (16 V, 24 V, 32 V, and 40 V)
  • ±2.5% matched LED current, up to 30 mA
  • ±2% accurate LED current at exponential mode