LED backlighting in portable products, the status can not be shaken, even of large-size LCD backlight LED Lights began to challenge the CCFL (cold cathode fluorescent lamp), the mainstream position; in the lighting field, LED as the semiconductor lighting the most critical components with energy saving, environmental protection, long life, maintenance-free, and many other sought after by the market. The drive (t5 high bay fixtures) circuit is an important part of the LED Panel (light emitting diodes) products, in terms of lighting, backlight or display board areas, the choice of the drive circuit technology architecture should be a specific application to match.
LED light-emitting principle (t5 high bay fixtures) is that it ends with a positive voltage, the semiconductor minority carrier and majority carrier complex, and release excess energy, causing the emission of photons. The main function of the LED driver circuit to convert AC voltage constant current power supply, in accordance with the requirements of the LED devices to match with the voltage and current of the LED. LED driver circuit to meet the safety requirements, and other basic functions should have two aspects:
First, as far as possible to maintain constant current characteristic, especially in the power supply voltage of ± 15% change should still be able to maintain the output current changes in the range of ± 10%. Using LED (t5 high bay fixtures) as a display or lighting or backlighting, the need for constant current drive, mainly due to:
(1) to avoid the drive current exceeds the maximum rating, affect its reliability.
(2) to obtain the desired brightness requirements, and to ensure that each LED brightness, color consistency.
Second, the drive circuit should be kept lower power consumption, so as to enable the efficiency of the LED Street Light system to maintain at a high level.
PWM (Pulse Width Modulation) technology is a traditional way of dimming it using a simple digital pulse repeatedly switch the LED driver, the system need only provide a wide, narrow different digital pulse, you can simply change the output current, so as to adjust the brightness of the LED. The advantages of the technology is able to provide high-quality white light, and the application of simple, high efficiency, but a fatal flaw is prone to electromagnetic interference, and sometimes will produce the human ear can hear the noise.