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LED drive circuit: Clingy application pursuit is efficient
From;    Author:Stand originally
[dispatch of Sai Di net] drive circuit is LED(glow diode) the main component of the product, its technology maturity as the dilate of LED market escalate. No matter be in,illuminant of illume, back still shows board domain, the choice of framework of drive circuit technology should match with specific application. As LCD (LCD) back illuminant, LED cannot shake in the position in portable product, even if is to be among the back illuminant of large size LCD, LED also begins to challenge fluorescent lamp of CCFL(cold cathode) mainstream position; And in illume domain, LED regards semiconductor illume as the most crucial part, more because carrying energy-saving, environmental protection, macrobian life, maintenance-free on the head,wait for a lot of aureola and get of the market chase after hold in both hands. However people ever can pay close attention to, in what glow " star " after one's death, how many is there " costar " dedicating silently? LED drive circuit is such " hero of behind the curtain " . Drive technology upgrades stage by stageThe glow mechanism of LED is in it two end are added to voltage, the minority that makes semiconductor medium carries stream child carry with majority stream child happen compound, give off excess energy, cause photon thereby blast off. The main function of LED drive circuit is alternating voltage changeover is constant current power source, finish the voltage with LED and electric current according to the requirement of LED parts of an apparatus at the same time match. It is with Bai Guang LED exemple, the talent of power supply voltage that Bai Guang LED needs about 3.6 bend over realizes appropriate brightness to control. However, product of most portable electron uses lithium ion batteries to make power supply, they are 4.2 bend over about after filling report, 2.8 bend over are about after safety puts report, LED of apparent Bai Guang cannot by batteries direct drive, consequently circuit of need use step up is used in whole batteries power supply is stabilized uninterruptedly for LED inside cycle. In addition, the brightness of LED of hope of the person that make much products plan applies a circumstance to be able to make corresponding change in what differ, this task also will give drive circuit goes finishing. Wide modulation of PWM(arteries and veins) the means moving light that the technology is a kind of tradition, it uses simple digital pulse, relapse switch LED driver, the system needs to offer only wide, narrow different digital type pulse, can realize a change simply to export electricity, adjust thereby the brightness of LED. The advantage of this technology depends on can offerring the Bai Guang of high quality, and application is simple, efficiency is tall, but a deadly defect is interference of easy generation electromagnetism, can produce the noise that person ear can hear even sometimes. Beijing considers limited company of flourishing electron technology presiding apparitor Pei Shiyan introduced a number to move optical technology to the reporter, use this technology to be able to control LED brightness in real time, and averted electromagnetism interference.
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