Overview of LED power supply and drive circuit technology.

As a new light source, the research on LED power supply and drive circuit has been developing in recent years. Unlike fluorescent lamp electronic ballasts, the main function of the LED drive circuit is to convert the ac voltage to dc voltage and to match the voltage and current of the LED at the same time. As plummeting silicon integrated circuit power supply voltage, LED working voltage are increasingly in the best range of output voltage, most IC for low voltage power supply technology are also applies to leds, especially the high power LED power supply. In addition, LED power supply should be able to take advantage of the scale economy brought by the gradual increase of low voltage IC power supply.
(1) main technical overview of LED power supply and drive circuit.
1) voltage transformation technology.
Power supply is an important component which influences the reliability and adaptability of LED light source. Current grid is 220 v alternating current (AC), and the LED light source is a semiconductor light source, usually with a low voltage DC power supply, this request in these lamps and lanterns or external setting AC - DC conversion circuit, to adapt to the characteristics of the LED drive current. Current power supply ways to choose a switch power supply, high frequency power supply, after capacitance step-down rectifier power supply, etc, according to the current stability, transient overshoot as well as the safety and reliability of different choices for different requirements.
2) life and cost of power supply and drive circuit.
LED life aspects, although the single star LED the life of 100000 hours, but its application must match the power conversion circuit, so the LED lighting appliance whole life must from optoelectronic integrated application into consideration. However, for the illumination use LED, the power supply and drive circuit must be more than 100,000 hours in order to meet the matching requirements, so that it no longer becomes the bottleneck factor of the semiconductor lighting system. Considering the long life and don't add too much cost, power supply and the life of the drive circuit and cost usually should not exceed one third of the total cost of the lighting system, at the beginning of the semiconductor lighting product development, must balance the good relationship between the power and the life of the drive circuit and cost.
3) programmable technology of the driver.
LED as light source, a remarkable characteristic is under the condition of low drive current can still maintain its lumen efficiency, at the same time for R.G.B. type polycrystalline mixed to form white light, the light through the development of a digital RGB hybrid control system for the LED, enabling users to in large range of LED brightness, color and color adjusted, give a person with a kind of brand-new visual enjoyment. In urban landscape lighting applications, LED light source can be under the microprocessor control can change according to different pattern, form night spectacular provide dynamic effect, relative to other LED light source is reflected in this respect will be a unique competitive advantage.
4) efficiency of power supply and drive circuit.
LED power supply and drive circuit, both must have certain required for LED to the constant current forward current output, and high conversion efficiency, electro-optic conversion efficiency is an important factor of semiconductor lighting, or you will lose the advantages of LED energy saving, the commercialization of switch power supply, its efficiency is about 80%, as a semiconductor lighting power supply, its conversion efficiency will be further ascension.