The backlight of the LCD screen is a light source behind the LCD screen. Its luminous effect will directly affect the visual effect of the LCM module. The LCD screen itself does not shine, it displays the graphics or it is the result of the light modulation. LCD backlight is designed independently or in a two in one way. Its backlight chip has a timer or Ctime pin that is familiar to you. Some are marked as CP or SCP. The function of this pin is to protect the delayed external capacitor terminal.
Working principle of LCD backlight
When the lamp overvoltage and overcurrent, lamp open circuit fault, and not immediately protection, but to a delay of 2 seconds, when powered up, through chip 3 a current source to the capacitor in the boot 2 seconds because capacitor voltage is lower than the threshold, turn off the protection signal through the door, at this time even if the overvoltage and overcurrent protection, signal can be cut off not trigger chip to stop working.
After 2 seconds, the capacitor charge more than 3V, and through the protection door, there will be overvoltage and over current, and the protection will appear immediately.