LED tube lightThe appearance of the LED tube is the same as that of the ordinary fluorescent tube, and the glass tube is also coated with a layer of white material, which is regarded as a kind of imitation makeup and maintains the same image as the fluorescent tube. We all know that LEDs need DC power to work, so how do LED tubes with the same length as ordinary fluorescent tubes work? The inside of the LED tube is attached to the glass tube wall with an LED strip. The tube takes electricity from both ends, one end is the 220V L line, and the other end is the N line. At the input end of the L line, there is a power conversion circuit board about 5×1cm in size. This power board converts the input AC 220V into DC power that the LED lamp beads can work.
The circuit is a DC step-down buck circuit, which belongs to the non-isolated low PF, PF>0.5 step-down quasi-resonant working mode. KP1052A is a highly integrated step-down quasi-resonant constant current power switch dedicated to LED lighting. On the same wafer, the KP1052A integrates the high voltage power MOSFET and controller. In addition, the chip also integrates a high-voltage start-up circuit and an inductor current zero-crossing detection circuit that does not require auxiliary windings. Using this function, the system works in a quasi-resonant mode and simplifies the system design to the greatest extent. KP1052A integrates complete protection functions to ensure the safe and reliable operation of the system, such as VDD under-voltage protection function, cycle-by-cycle current limit, overheat protection, LED short circuit protection, etc.