The working principle of LCD screen backlight: Whether designed independently or in a two in one manner, the backlight chip of the LCD screen has a timer or Ctime pin that is familiar to everyone. Some are labeled as CP or SCP, and this pin is used to protect the delay external capacitor terminal.
When there is an overvoltage, overcurrent, or open circuit fault in the lamp tube, it is not immediately protected, but a delay of about 2 seconds. After powering on and starting up, the capacitor is charged through a 3 microampere current source inside the chip. Within 2 seconds of starting up, the protection signal passage gate is closed because the voltage on the capacitor is below the threshold. At this time, even if overvoltage or overcurrent occurs, the protection signal is cut off and cannot trigger the chip to stop working.
After 2 seconds, if the capacitor charges more than 3V and the protection door is opened, overvoltage and overcurrent will occur again, and protection will immediately occur.
|
中文版
English 
