LED lighting has been making rapid progress in the near future, and LED has been widely recognized as a clean and green light source. LED light source has long service life, energy saving and power saving, simple and convenient application, low cost of use, and therefore will be applied in a large amount in home lighting. According to 2008 survey by OSRAM Optics Semiconductor, the number of home lighting units in the world is about 500. Billion. The technology of LED light sources has matured, and the luminous lumens per watt have grown rapidly, prompting them to reduce their prices year by year. Taking the 1W LED light source as an example, the price in the spring of 2008 was one-third of the price in the spring of 2006, and the spring of 2009 will fall to a quarter in 2006. The massive market of LED green lamps and the continuous and stable growth for several years will be the super tsunami of the IC market following the VCD, DVD, mobile phone and MP3 consumer electronics market! LED lamps are widely recognized for their high energy-saving, long-life, and environmental-friendly advantages. LED high energy-saving: DC drive, ultra-low power (single tube 0.03 watts -1 watts) electro-optical power conversion close to 100%, the same lighting effect than traditional light sources energy saving more than 80%. LED long life: LED light source is called longevity light. Solid cold light source, epoxy resin encapsulation, there is no loose part of the lamp body, there is no weakness in the filament light-emitting, heat deposition, light decay, etc., the service life can reach 50,000 to 100,000 hours, and the service life is longer than the traditional light source. More than times. LED environmental protection: LED is a green light source, environmental protection and better efficiency. No ultraviolet and infrared rays in the spectrum, low heat and no flicker, no radiation, and the waste can be recycled, no pollution, no mercury element, cold light source, can be safely touched, belonging to a typical green lighting source. LED light source operating characteristics LED light source for illumination VF voltage is very low, generally VF = 2.75-3.8V, IF in the 15-1400mA; so the output voltage of the LED driver IC is VF XN or VF X1, IF constant current in 15- The LED light source used in 1400mA.LED lamps has two types: low power (IF=15-20mA) and high power (IF>200mA). The low power LED is mostly used for LED fluorescent lamps, decorative lights and grille lights; it is used for high power LEDs. Do home lighting, spotlights, underwater lights, wall washers, street lights, tunnel lights, car work lights, etc. The power LED light source is a device driven by a low voltage and a large current. The intensity of the light emission is determined by the size of the current flowing through the LED. If the current is too strong, the LED light will be attenuated. If the current is too weak, the light emitting intensity of the LED will be affected. Therefore, the LED The driver needs to provide a constant current power supply to ensure the safety of high power LED use while achieving the desired luminous intensity. In the field of LED lighting, to reflect the characteristics of energy saving and long life, choosing a good LED driver IC is essential, there is no good driver IC matching, the advantages of LED lighting can not be reflected. LED lighting design requires attention to technical details LED lighting requirements for low voltage driver chips: 1. The nominal input voltage range of the driver chip should meet DC8-40V to cover the application surface. If the withstand voltage can be more than 45V, the output voltage of a simple bridge rectifier with the AC 12V or 24V input will follow the grid voltage. Fluctuation, especially when the voltage is high, the output DC voltage will be too high. If the driving IC can not adapt to a wide voltage range, it will often be broken when the power grid voltage increases, and the LED light source is also burned. 2. The nominal output current requirement of the driver chip is greater than 1.2-1.5A. As a LED light source for lighting, the nominal operating current of a 1W power LED light source is 350mA, and the nominal operating current of a 3W power LED light source is 700mA. Larger currents require more current. Therefore, the driver ICs used in LED lighting fixtures must have sufficient current output. When designing a product, the driver IC must work in a 70-90% optimal working area with a full negative output. Driver ICs with full and negative output currents dissipate heat in tight spaces in lamps, fatigue, and premature failure. 3. The output current of the driver chip must be constant for a long time. The LED light source can emit light stably and the brightness will not flicker. When the same driver chip is used under the same conditions, the output current should be as uniform as possible, that is, the discreteness should be small. High-volume automated production line production can be effective and orderly; for the output current of a certain discrete drive chip must be selected before delivery or put into the production line, adjust the resistance of the PCB board current setting resistor (RS), so that The production of LED lamps and constant current driver board for the same LED light source brightness uniformity, to maintain the consistency of the final product. 4. The driver chip package should be conducive to the rapid heat dissipation of the driver chip die, such as the die directly bonded to the copper plate, and there is a pin directly extended to the outside of the package, for direct welding on the PCB board copper foil Rapid heat conduction (Figure 1). For example, on a 4X4mm wafer die, if a current of 300-1000mA is passed for a long time, there must be power consumption, and it will inevitably generate heat. The physical heat dissipation structure of the chip itself is also crucial. 5. The ability of the driver chip to resist EMI, noise, and high voltage is also related to the ability of the entire LED lamp product to successfully pass CE, UL, and other certifications. Therefore, the driver chip itself must use excellent topological structure and high voltage at the beginning of design. Production Process. 6. The power requirement of the driver chip itself is less than 0.5W, and the switching frequency requirement is greater than 120Hz to avoid visible flicker caused by the power frequency interference. LED green lighting promotes the development of the driver chip to innovative design. LED lighting is inseparable from the driver chip, so it requires a variety of functions LED light source driver IC. LED lamps use below 36V AC power supply can be considered non-isolated power supply, such as the use of 220V And 100V AC power should consider isolated power supply. Directly using the AC100-220V driver chip, due to the application of the volume of demanding, technically there are still higher requirements, greater difficulty, at present all countries are working hard to develop. The massive market demand for LED lamps has given all IC design companies a chance to succeed again. They will quickly transform and produce products early and win many opportunities.