In 2011, Australia has taken the lead in banned the use of incandescent lamps, which kicked off the large-scale popularization of LED lamps. In addition, with the EU countries, Japan, Canada and other countries will ban the use of incandescent lamps in 2012, the lighting of LED lamps The penetration rate will be further enhanced, which makes the thousands of LED lighting manufacturers in China's Nuggets green lighting revolution rejoice - because a huge market is about to open, and this time the main players are Chinese manufacturers. However, it should be noted that LED lamps should be popularized, not only need to significantly reduce costs, but also need to solve the problem of energy efficiency and reliability. How to solve these problems, Doug Bailey, vice president of marketing for Power Integrations, shared the design of high-efficiency and high-reliability LED lamps . Five advices.
First, do not use bipolar power devices
Doug Bailey pointed out that because bipolar power devices are cheaper than MOSFETs, typically around 2 cents, some designers use bipolar power devices to reduce LED drive costs, which can seriously affect circuit reliability because The temperature of the LED driver board increases, and the effective working range of the bipolar device will shrink rapidly. This will cause the device to malfunction when the temperature rises, which will affect the reliability of the LED lamp. The correct way is to use the MOSFET device and the MOSFET device. Lifespan is much longer than bipolar devices.
Second, do not use a 600V MOSFET
MOSFETs with a withstand voltage of 600V are relatively cheap. Many people think that the input voltage of LED lamps is generally 220V, so the withstand voltage of 600V is enough, but in many cases the circuit voltage will reach 340V. In the case of surge, the 600V MOSFET is easily broken down. This affects the life of LED lamps. In fact, the choice of 600V MOSFETs may save some cost but the cost of the entire board, so, "Do not use 600V withstand voltage MOSFET, it is best to use MOSFET with over 700V. "He stressed.
Third, try not to use electrolytic capacitors
Do you want to use electrolytic capacitors in the LED driver circuit? At present, there are supporters and opponents. Supporters believe that if the temperature of the board can be controlled well, the purpose of extending the life of the electrolytic capacitor can be achieved in turn. For example, a high-temperature electrolytic capacitor with a life of 105 degrees and a lifetime of 8000 hours is selected, according to the estimated life expectancy of the electrolytic capacitor. “Every time the temperature is lowered by 10 degrees, the life is doubledâ€, then it has a working life of 16,000 hours in a 95 degree environment, a working life of 32,000 hours in a 85 degree environment, and a working life of 64,000 hours in a 75 degree environment, if Lower operating temperature, longer life! From this point of view, as long as the choice of high-quality electrolytic capacitors has no effect on the life of the drive power!
Other proponents believe that the low-frequency flicker caused by the high ripple current caused by electroless capacitors will cause physiological discomfort to some people's eyes. The large amplitude of low-frequency ripple will also cause some digital camera equipment to appear poor. A brightly lit grid of flickering lights. Therefore, high-quality light source lamps still need electrolytic capacitors. However, opponents believe that electrolytic capacitors will naturally age. In addition, the temperature of LED lamps is extremely difficult to control, so the life of electrolytic capacitors will inevitably decrease, thus affecting the life of LED lamps.
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