Analysis: Design of driving power supply for LED lamps

To popularize LED luminaires, not only need to significantly reduce costs, but also to solve the problem of energy efficiency and reliability, how to solve these problems, Power Integrations marketing vice president Doug Bailey shared five points of advice on high-efficiency and high-reliability LED luminaire design .

First, do not use bipolar power devices

Doug Bailey pointed out that because bipolar power devices are cheaper than MOSFETs, generally about 2 cents, some designers use bipolar power devices to reduce the cost of LED driving , which will seriously affect the reliability of the circuit, because with LED As the temperature of the driver board increases, the effective working range of the bipolar device will shrink rapidly, which will cause the device to malfunction when the temperature rises, thus affecting the reliability of the LED lamp. The correct way is to select the MOSFET device and the service life of the MOSFET device. It is much longer than a bipolar device.

Analysis: Design of driving power supply for LED lamps

Second, the MOSFET's withstand voltage should not be lower than 700V

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. Therefore, the life of the LED lamp is affected. In fact, the selection of the 600V MOSFET may save some cost but the cost of the entire circuit board. Therefore, "Do not use a 600V MOSFET, and it is better to use a MOSFET with a withstand voltage exceeding 700V. He emphasized.

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 doubled”, 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!

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