A New Offline HV LED IC Driver

Traditional offline LED driver light the LED near the peak of the input voltage,which leads to efficient LED lighting time is short,the problem of low lumen output.Meanwhile,due to the transmission grid disturbance,low productivity and poor lack TRIAC dimming compatibility also severely limits the development of off-line LED.For this situation,we designed a high-performance off-segmented LED Constant stream driver chips.In order to solve the LED on-time short question,four built-in high-voltage MOS segmented driver the LED.The four MOS are controlled by the respective driver amplifier.This structure ensures that a small number of LED is still turned on at low voltage.So the lights time of LED grow in the whole cycle of the AC power and LED lumens total output increase.Meanwhile,the grid voltage disturbance caused the input power of chip being unstable,when the grid voltage goes high may lead to chip overheating problems.Designed with a precision voltage current conversion transconductance amplifier will detect the input voltage into a current signal which is used to adjust the LED current.This ensure the grid fluctuate between 200Vrms and 260Vrms,the output power variation less than ±5%.Chip detect TRIAC dimming angle and control the maintain current of TRIAC with a hysteretic comparator and acurrent source,that resolve TRIAC dimmers dimming LEDs occurring lights flicker without affecting efficiency.In addition,temperature compensation and over-temperature protection,to further ensure security and stability of the system.This article uses the Pspice software for circuit simulation,L-Editor Software for territory production.The chip choose using high pressure on China 700V BCD process,the process of making high-pressure LDNMOS chip input voltage up to 700V.Considering the cost,thermal and other requirements select a reasonable cost package SOP8.During the testing phase,on the basis of high-precision bandgap reference circuit design,we use the fuse trim technology to achieve a high accuracy of LED current up to 3%.Test results show that the parameters and functions meet expectations,the chip have a good market prospects.