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

LM3697 Simplified Block Diagram

The LM3697 device supports most hero LCD panel backlight units in the market so as to simplify backlight design. It supports up to 3 strings with 12 LEDs in series for each string: a total of 36 LEDs (depending on the LED forward-drop voltage, 40 V VOUT_MAX). The device also supports exponential and linear dimming mode so as to erase panel twinkling during extreme low-brightness conditions. The LM3697 also supports CABC function to get better backlight performance in video or movie mode. The flexible 500-kHz and 1-MHz switching frequency selections help designers easily use different inductors. Figure 1-1 illustrates the LM3697 LED backlight driver.

GUID-CC1711BF-43C6-46D9-AE0A-C8F0C1E0E42C-low.gifFigure 1-1 LM3697 LED Backlight Driver