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LED lamp driver working principle

Ether Photoelectric Ltd | Updated: Sep 01, 2017

LED lighting in the near future has been leap in the development of LED as a clean green light source has been widely recognized. LED light source long life, energy saving, easy to use, the use of low cost, and thus in the LED flashlight, LED miner's lamp and portable lighting; in architectural lighting, decorative lighting, signage lighting; in the car dashboard backlight, front and rear fog lights , The third brake lights, directional lights, taillights; and in the home lighting will be a massive application, OSRAM optical semiconductor company in 2008 survey statistics, the global annual home lighting lamp holder shipments of about 50 billion. LED light source technology matures, the rapid growth of luminous lumens per watt, prompting its annual decline in price. To 1W LED light source, for example, the price of spring 2008 is the price of spring in 2006 one-third of the spring of 2009 will fall to one quarter of 2006.

LED green lighting market and the stability of several years of growing demand will be integrated circuit industry following VCD, DVD, mobile phone, MP3 after the consumer electronics market super tsunami! LED lamps of high energy, long life, and environmental protection of the superior performance has been generally recognized. LED high energy: energy-saving energy pollution is environmentally friendly. DC drive, ultra-low power (single tube 0.03 watts -1 watts) electro-optical power conversion close to 100%, the same lighting effect than the traditional light source more than 80% energy saving.

LED environmental protection: LED is a green light source, better environmental benefits. Spectrum without ultraviolet and infrared, low heat and no flicker, no radiation, and waste can be recycled, no pollution does not contain mercury elements, cold light source, you can safely touch, is a typical green lighting source. Lighting VF voltage is very low, the general VF = 2.75-3.8V, IF 15-1400mA; Therefore, LED driver IC output voltage is VF X N or VF X 1, IF constant current at 15-1400mA. LED lamps use LED light source with low power (IF = 15-20mA) and high power (IF> 200mA) two kinds of low power LED used to do LED fluorescent lamp, decorative lights, grille lights; high power LED used to do Home lighting, spotlights, underwater lights, wall washer, street lamps, tunnel lights, car work lights and so on. Power LED light source is a low voltage, high current drive device, the intensity of its luminous flow through the LED current size, the current is too strong will cause the LED light attenuation, the current is too weak will affect the LED luminous intensity, Drive need to provide constant current power supply to ensure the safety of high-power LED, while achieving the desired luminous intensity. In the field of LED lighting, to reflect the characteristics of energy saving and long life, choose a good LED driver IC is essential, there is no good match between the driver IC, LED lighting can not reflect the advantages.

1, the main parameters of LED work is VF, IF, other related to the color / color temperature / wavelength / brightness / light angle / efficiency / power consumption. The LED is a P-N junction diode, and only enough forward voltage is applied to conduct current. VF forward voltage is set for the LED to establish a normal working state, IF forward current is to make LED light, luminous brightness and the current flow is proportional. LED VF Nominal voltage: 3.4V ± 0.2V.

2, LED IF current application according to the need to use, the file can not be mixed. LED lights with the file LED current: high-power lighting with its packaging from the finished product point of view is a single chip, in fact, with N LED die package in a unit. They are arranged in series and parallel, they are N series, and then N parallel, and then by the two-point power supply. When you choose to pay special attention to its VF and IF. LED lighting drive principle LED lighting drive need to first high-voltage alternating current into low-voltage alternating current (AC / AC), and then low-voltage alternating current through the bridge rectifier into low-voltage direct current (AC / DC), and then through the high efficiency DC / DC switching regulator bucks and transforms into a constant current source, which outputs a constant current to drive the LED light source. LED light source is according to the design requirements of the lamp by the small power or high power LED multi-string and more. Each string of IF current is designed according to the selected LED light source IF, the total forward voltage VF is the sum of N LEDs. LED lighting optional 36V AC power supply can be considered non-isolated power supply, such as the use of 220V and 100V AC power supply should be considered isolated power supply.

3, the current MR11, MR16 spotlights, underwater lights, wall lights, street lamps, tunnel lights, automotive lights and other LED lamps and most of the best use of heat sink comes with copper or aluminum plate 1W, 3W high power LED light source, AC / DC12-36V power supply, which requires the use of DC / DC buck (Buck) + constant current to the LED to provide VF and IF. LED lamps are mostly used low-voltage power supply, so in this type of lamp circuit design, the number of LED series in 1-9, especially 1-3 is common. The total delta VF of the series should be lower than the power supply Vin. Such as three LED series, VF = 3.4V X 3 = 10.2V. In Vin> 12V, can work properly. MR11, MR16 spotlights are common 1W X 3 series or 3W X 1; underwater lights are common 1W X 3 series 2-3 and three groups; wall is common 1W X 7-9 series; street light Common is 1W X 9 series 3 and 4 - 6 a group; car work lights are common 1W X 3-6 series 3 and. Of course, the serial and parallel LED program is a variety of series number and its working voltage (Vin), where the DC12-36V operating voltage. The current 1W LED light source heat better, so choose more.