Five ways to solve the LED lamps and lanterns, high efficiency and reliable "difficult problem.

Five ways to solve the "LED lamps and lanterns, high efficiency and reliable "difficult problem.

Discovery
2011 all over the world of mass popularity LED lamps and lanterns to uncover the prelude, it makes the nuggets green lighting revolution LED lamps and lanterns of China for thousands of home triumphant--because the manufacturer of a huge market will open, and this time the Chinese manufacturers is to sing leading role. The LED lamps and lanterns to spread, not only need to reduce costs, the more need to solve the problem of energy efficiency and reliability, how to solve these problems, PowerIntegrations market vice President of marketing DougBailey share the high efficient and reliable LED lamps and lanterns of design five advice.

Don't use a bipolar type power components

DougBailey points out that because the bipolar type power components cheaper than MOSFET, general is about two cents a, so some designers to reduce cost, use LED drive bipolar type power components, this will seriously affect the reliability of the circuit, drive circuit board with LED temperature because of ascension, bipolar type device of effective work scope to unwind quickly, this can lead to a device in the temperature rises fault which affect the reliability of the LED lamps and lanterns, the right way is to choose MOSFET device, the service life of the MOSFET device far longer than a bipolar type device.

Try to use integrated MOSFET

If the design of power LED lamps and lanterns is not very high, Doug suggest using integrated the MOSFET LED drive products, because the advantage of this is integrated MOSFET conduction less resistance, heat generation to the score of the set, in another, less is integrated MOSFET is controller and an FET together, generally overheated shut off the function, in the MOSFET overheating will be shut off the circuit to protect the purpose of lamps and lanterns, which LED to the LED lamps and lanterns is very important, because the LED lamps and lanterns are generally small and difficult to air cooling. "Sometimes happens in overheating LED the burning hurt, but our plan never like this." He said.

Try to use single level architecture circuit

Doug says some LED circuit in two level structure, namely "power factor correction (PFC) + isolation DC/DC converter" framework, and the design will reduce the efficiency of the circuit. For example, if the efficiency of PFC was 95%, and the DC/DC part of efficiency is 88%, the efficiency of the whole circuit will be reduced to 83.6%! "PI LinkSwitch-PH and the device will PFC/CC controller, a 725 VMOSFET and MOSFET drive into a single, integrated package will power circuit of the efficiency to 87%!" Doug points out, "such a device could be greatly simplified circuit board layout design, most can save traditional segregation flyback design of the type used in the 25 components of components including high pressure! Save large capacity electrolytic capacitors and light coupling device." Doug says LED two level concept is applicable to have to use the second constant current driving circuit can drive LED the constant current PFC old drive. These design have been out of date, no longer is cost effective, so in most cases had better use single stage design.

Doug revealed, PI company in 2010 LED drive shipments in calculating its market share occupy global the first! The massive customers use let PI can deeply understand the trend of application and LED to continuously introduce the new products to meet customer demand. Looking to the future, he said in 2011 China indoor LED lighting, LED fluorescent lamp and LED street lamp will have a good application.

Don't choose 600 V voltage MOSFET

600 V voltage MOSFET is cheaper, many think that LED the lamps and lanterns of the input voltage is usually 220 V, so compression is 600 V enough, but a lot of time to 340 V voltage circuit, in a surge of time, 600 V MOSFET is easy to be punctured, thus affecting the LED the life of lamps and lanterns, actually choose 600 VMOSFET may save some cost but pay the cost of the whole circuit board is, so, "don't choose 600 V voltage MOSFET, had better choose the more than 700 V voltage of the MOSFET." He emphasized.

Try not to use electrolytic capacitors

The LED drive circuit of whether or not to use electrolytic? There are supporters has opponents, supporters say if the temperature control circuit, in turn prolong the service life of the electrolytic capacitor a purpose, such as choose 105 degrees for life 8000 hours of high temperature capacitors, according to popular electrolytic life estimation formula "temperature each reduce 10 degrees, double life," then it in 95 degrees environment for 16000 hours, the working life in 85 degrees environment for 32000 hours, the working life in 75 degrees environment for 64000 hours working life, if the actual work more low temperature, then they will live longer!!!!! So it seems that selects high quality as long as the electrolytic capacitors to drive the life span of the power supply is not any effect! And supporters think from no electrolytic brings high ripple current to the low frequency for some eye twinkle will cause physical discomfort, a large range of low frequency ripple can also lead to some digital camera equipment appear difference frequency flashing light and dark grid. So, high quality light lamps and lanterns or need electrolytic capacitors. But opponents argued electrolytic capacitor, in addition, will the natural aging LED lamps and lanterns is very difficult to control the temperature, so the life span of the electrolytic capacitors will reduce, thus affecting the LED the life of lamps and lanterns.

To this, DougBailey think, driving circuit of input in LED to consider not capacitors, actually use the PI LinkSwitch-PH can save electrolytic capacitor, PI single stage of PFC constant current design can let/designers save large capacity in the output capacitance, circuit, can use the high pressure ceramic capacitors instead of electrolytic so as to enhance the reliability, "some people in the design of the two levels of circuit, in the output is using a 400 V capacitors, which would seriously affect the reliability of the circuit, the proposal USES single level circuit with ceramic capacitors." He emphasized. "For not too concerned about light function, high temperature environment and the need of high reliability of the industrial application for, I strongly suggest that does not use the electrolytic capacitor design."

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