本文關鍵詞： LED驅動芯片 電流自適應調(diào)節(jié) 溫度 發(fā)光二極管 調(diào)光　出處：《湘潭大學》2015年碩士論文　論文類型：學位論文

【摘要】：LED(Light Emitting Diode,發(fā)光二極管)作為一種新型綠色光源,以其高效、節(jié)能、環(huán)保、長壽命等諸多方面的優(yōu)勢而備受關注,成為近年各國競相研究的熱點,其相關技術和產(chǎn)業(yè)得到了迅猛發(fā)展,已被廣泛應用于諸如背光顯示、信號指示、各類照明等多個領域,特別是在照明應用領域中,白光LED正在逐步取代其他傳統(tǒng)光源而成為照明光源的新銳主力。但LED的實際應用性能很大程度要受到供電電壓以及正向電流穩(wěn)定性、工作溫度水平等因素的影響,因而其在照明應用中的種種優(yōu)勢得以發(fā)揮的一個重要保障是配備有性能優(yōu)良的LED驅動器。對于大功率LED照明應用而言,溫度是影響其工作性能的重要因素。當溫度升高,LED允許流過的最大電流要求隨之減小,否則,高溫會造成LED發(fā)光性能及其使用壽命嚴重衰減;為確保正常應用,驅動電路必須對實際應用中的LED實施溫度補償。另外,照明應用場合通常杜絕照明設施突然熄滅而造成視覺亮度驟變,而傳統(tǒng)的過溫關斷方案顯然不能滿足這一要求,并且容易發(fā)生頻繁關斷現(xiàn)象。同時考慮到LED電光特性具有的線性相關性,在LED照明應用中,電流可隨溫度自適應調(diào)控的驅動方式會更具優(yōu)越性。本論文主要開展了一種電流可隨系統(tǒng)溫度自適應調(diào)節(jié)的LED驅動芯片的研究與設計。電路設計采用具有電磁干擾小、噪聲電壓低、響應速度快、恒流精度高、成本低廉等優(yōu)點的線性調(diào)整型比例采樣結構,實現(xiàn)驅動電路可跟隨系統(tǒng)溫度變化自適應工作于正常恒流輸出、自適應調(diào)控輸出、以及極端過熱關斷保護三種狀態(tài)。并在此基礎上實現(xiàn)3位8階數(shù)字調(diào)光、PWM調(diào)光以及多種保護的功能。論文給出了芯片的整體電路結構框圖及其主要的性能參數(shù)指標,結合電路詳細闡述了電流自適應溫度調(diào)節(jié)功能的實現(xiàn)原理,并利用Cadence電路設計軟件,按照自底向上的設計方法,完成對芯片內(nèi)部的各子模塊電路的分析設計和仿真驗證,最后對驅動芯片整體電路的功能進行全局仿真驗證。仿真結果表明,芯片可于6.5V~30V的寬輸入電壓范圍內(nèi)穩(wěn)定工作,正常溫度范圍(0~80℃),驅動電路實現(xiàn)±1.8%的恒流精度;自適應調(diào)控溫度區(qū)間內(nèi),實現(xiàn)電流最大可調(diào)幅度為160mA,電路熱功耗最高可降71%,有效抑制溫升;在此調(diào)節(jié)范圍內(nèi),LED光通量最大減小45%,人眼主觀亮度改變量不超過5%;若出現(xiàn)溫升程度較為嚴重的情況,當達到極端過熱關斷溫度(110℃)時,電路實施關斷保護。同時,電路能夠實現(xiàn)良好的調(diào)光及保護功能。芯片最終的仿真結果滿足既定設計要求。
[Abstract]:As a new type of green light source, LED(Light Emitting Diode has attracted much attention because of its advantages of high efficiency, energy saving, environmental protection, long life and so on. In recent years, the related technology and industry has been developed rapidly. It has been widely used in many fields such as backlight display, signal indication, various lighting and so on. Especially in the field of lighting applications. White LED is gradually replacing other traditional light sources to become the new main source of lighting, but the actual application performance of LED is due to the power supply voltage and forward current stability to a great extent. Because of the influence of working temperature level and other factors, one important guarantee of its advantages in lighting application is to equip with LED driver with excellent performance. For high-power LED lighting applications. Temperature is an important factor affecting the performance of LED. When the temperature increases, the maximum current requirement of LED can be reduced, otherwise, the luminescence performance and service life of LED will be seriously attenuated at high temperature. In order to ensure the normal application, the driving circuit must implement temperature compensation to the LED in the practical application. In addition, the lighting applications usually prevent the sudden extinguishment of lighting facilities and the sudden change of visual brightness. However, the traditional overtemperature turn-off scheme obviously can not meet this requirement, and it is easy to occur frequent turn-off phenomenon. Considering the linear correlation of the electro-optic characteristics of LED, it is used in LED lighting applications. The drive mode of current can be adjusted adaptively with temperature will be more advantageous. In this paper, the research and design of LED driver chip which can adjust current to system temperature adaptively is carried out. The circuit is designed with electricity. Little magnetic interference. Low noise voltage, fast response speed, high accuracy of constant current, low cost and other advantages of linear adjusted proportional sampling structure, the drive circuit can work adaptively to the normal constant current output following the temperature change of the system. Adaptive control output and extreme overheat turn-off protection are three states. On this basis, 3-bit 8-order digital dimming is realized. PWM dimming and various protection functions. This paper gives the whole circuit structure block diagram of the chip and its main performance parameter index. Combined with the circuit, the realization principle of the current adaptive temperature regulation function is described in detail. And using the Cadence circuit design software, according to the bottom-up design method, complete the analysis, design and simulation of each sub-module circuit inside the chip. The simulation results show that the chip can work stably in the wide input voltage range of 6.5 V or 30 V, and the normal temperature range is 0 ~ 80 鈩，

本文編號：1459821