电流自适应温度的LED驱动电路设计

发布时间：2018-01-24 10:28

  本文关键词： LED驱动芯片 电流自适应调节 温度 发光二极管 调光　出处：《湘潭大学》2015年硕士论文　论文类型：学位论文

【摘要】：LED(Light Emitting Diode,发光二极管)作为一种新型绿色光源,以其高效、节能、环保、长寿命等诸多方面的优势而备受关注,成为近年各国竞相研究的热点,其相关技术和产业得到了迅猛发展,已被广泛应用于诸如背光显示、信号指示、各类照明等多个领域,特别是在照明应用领域中,白光LED正在逐步取代其他传统光源而成为照明光源的新锐主力。但LED的实际应用性能很大程度要受到供电电压以及正向电流稳定性、工作温度水平等因素的影响,因而其在照明应用中的种种优势得以发挥的一个重要保障是配备有性能优良的LED驱动器。对于大功率LED照明应用而言,温度是影响其工作性能的重要因素。当温度升高,LED允许流过的最大电流要求随之减小,否则,高温会造成LED发光性能及其使用寿命严重衰减;为确保正常应用,驱动电路必须对实际应用中的LED实施温度补偿。另外,照明应用场合通常杜绝照明设施突然熄灭而造成视觉亮度骤变,而传统的过温关断方案显然不能满足这一要求,并且容易发生频繁关断现象。同时考虑到LED电光特性具有的线性相关性,在LED照明应用中,电流可随温度自适应调控的驱动方式会更具优越性。本论文主要开展了一种电流可随系统温度自适应调节的LED驱动芯片的研究与设计。电路设计采用具有电磁干扰小、噪声电压低、响应速度快、恒流精度高、成本低廉等优点的线性调整型比例采样结构,实现驱动电路可跟随系统温度变化自适应工作于正常恒流输出、自适应调控输出、以及极端过热关断保护三种状态。并在此基础上实现3位8阶数字调光、PWM调光以及多种保护的功能。论文给出了芯片的整体电路结构框图及其主要的性能参数指标,结合电路详细阐述了电流自适应温度调节功能的实现原理,并利用Cadence电路设计软件,按照自底向上的设计方法,完成对芯片内部的各子模块电路的分析设计和仿真验证,最后对驱动芯片整体电路的功能进行全局仿真验证。仿真结果表明,芯片可于6.5V~30V的宽输入电压范围内稳定工作,正常温度范围(0~80℃),驱动电路实现±1.8%的恒流精度;自适应调控温度区间内,实现电流最大可调幅度为160mA,电路热功耗最高可降71%,有效抑制温升;在此调节范围内,LED光通量最大减小45%,人眼主观亮度改变量不超过5%;若出现温升程度较为严重的情况,当达到极端过热关断温度(110℃)时,电路实施关断保护。同时,电路能够实现良好的调光及保护功能。芯片最终的仿真结果满足既定设计要求。
[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，

本文编号：1459821