Three tips for 'efficient and reliable' LED lamp design

'China Building Materials Network' kicked off the large-scale popularization of LED lamps around the world in 2011, this has inspired thousands of LED lighting manufacturers in China in the Nuggets green lighting revolution-because a huge market is about to open, and this time the protagonist is Chinese manufacturers. If LED lamps are to be popularized, it not only needs to greatly reduce the cost, but also needs to solve the problems of energy efficiency and reliability. How to solve these problems, let's share three suggestions on the design of high-efficiency and high-reliability LED lamps. Do not use bipolar power devices Douglas Bailey pointed out that because bipolar power devices are cheaper than MOSFET, usually about 2 cents, some designers use bipolar power devices in order to reduce LED driving costs, this will seriously affect the reliability of the circuit, because with the increase of the temperature of the LED drive circuit board, the effective working range of the bipolar device will be rapidly reduced, this will cause the device to fail when the temperature rises, thus affecting the reliability of LED lamps. The correct way is to choose MOSFET devices, whose service life is much longer than that of bipolar devices. Try to use integrated MOSFET if the designed LED lamp power is not very high, Doug suggests using LED driver products with integrated MOSFET, because the advantage of doing so is that the on resistance of integrated MOSFET is less, the heat generated is less than that of discrete MOSFET. In addition, the integrated MOSFET is a controller and FET together, which generally has overheating shutdown function, when MOSFET is overheated, it will automatically turn off the circuit to protect LED lamps, which is very important for LED lamps, because LED lamps are generally small and difficult to dissipate air. Sometimes LED Burns and hurts people due to overheating, but our plan has never been like this. He said. Try to use a single-stage architecture circuit Doug means that some LED circuits adopt a two-stage architecture, namely PFC (Power factor correction) The architecture of isolated DC/DC converter will reduce the efficiency of the circuit. For example, if the efficiency of PFC is 95 and the efficiency of DC/DC is 88, the efficiency of the whole circuit will be reduced to 83. 6! LinkSwitch of PI- The PH device integrates PFC/CC controller, a 725VMOSFET and MOSFET driver into a single package at the same time, improving the efficiency of the drive circuit to 87! Doug pointed out that such devices can greatly simplify the layout design of circuit boards, and can save 25 components used in traditional isolated flyback design! The omitted components include high-voltage large-capacity electrolytic capacitors and Optocouplers. Doug said that the LED two-stage architecture is suitable for old drivers that must use a second constant current drive circuit to enable PFC to drive LED constant current. These designs are outdated and no longer cost-effective, so single-stage designs are preferred in most cases.