LED street lamp market's future depends on the reliability issue is resolved

Government are currently carrying out most of the world lighting upgrade, the first step is to install LED lights in the new development area, then, LED light will replace the existing old street lighting. According to expect in the next five years, today most of the lights are LED lighting will be replaced.
However, LED lights are facing a big problem is the low reliability because it is mainly used for outdoor lighting, face a variety of extreme environmental conditions, such as long withstand sun and rain, thunder and lightning, temperature changes may be more so. LED lights to be recognized by the market and large-scale use, we must first solve the reliability issues.
TI Semiconductor Division Business Development Manager Liu Chao
TI High Performance Analog Semiconductor Division, Business Development Manager, Dr. Liu Xuechao, said: "LED street lamp market prospect, but must address reliability issues."
LED lights is an optical, thermal and electronics components of complex systems, although a longer LED life of its own, but if poorly designed LED driver circuit, such as the use of low-quality active or passive devices, and the overall life of the drive circuit not match with the LED, LED lights will affect the quality and life.
Furthermore, LED thermal management and heat dissipation is also very important, once the temperature higher than 100 ℃, LED itself, the reliability will be affected. Of course, LED early failure, and transient assembly of local defects and other factors, also led to the LED may fail occasionally, if not take appropriate protective measures diversion, a single LED failure will lead to a whole string of LED does not affect the overall effect of street lighting .
Liu Chao stressed that: "LED lamp is a complex system design, involving light, electricity, heat, mechanical and other fields. Mainly on the drive power in terms of efficiency and reliability problems. First, the driver power supply temperature is high (usually 70 degrees up and down), this way, I hope to drive power efficiency (including the constant voltage with constant current) efficiency reaches a certain height (eg> 90%), reducing the drive power of the temperature, increase reliability, and secondly, the traditional driver topology is more complex, including the PFC, PWM isolation and constant current DC / DC three circuits (see below), components and more, low reliability, especially electrolytic capacitors and opto-sensitive devices. "
Thus, in the process of designing LED bulbs, LED temperature must be well taken into account management or cooling problem, the LED operating temperature remains below its junction temperature (maximum junction temperature of 150 ℃), is generally recommended to be less than the LED operating temperature 100 ℃, avoid affected the reliability of the LED. In addition, LED spotlight circuit designer must carefully choose the circuit in the active or passive devices, to ensure match with LED life. For example, designers should avoid the use of electrolytic capacitors as much as possible, because the capacitor under the conditions in long-term use may cause leakage and result in shortened life expectancy.
Furthermore, LED lighting market in the overall, LED lights are all LED lighting applications the highest power, and therefore require multiple power levels and complex topology to meet the power factor correction (PFC), total harmonic distortion (THD) , 85 PLUS efficiency and other standards and regulations, and multi-string LED current constant demand.
Liu Chao also said: "To solve the problem of circuit reliability of LED lights, drive topology must improve, improve efficiency, reduce component count, while also further reducing costs."