一种带有软启动与欠压锁定电路的新型可调光LED驱动器

本文提出了一种基于电流PWM模式DC-DC转换器的全集成LED驱动器。设计了一个软启动电路,用以消除启动瞬间的浪涌电路与过冲电压。此外,为了调整LED的亮度但不产生色散,同时获得较宽的调光范围和较高的效率,设计了一个PWM调光电路。另外,设计了一个内部补偿网络,用来消除占空比大于50%时产生的次谐波振荡,以保证LED驱动器的环路稳定性。UVLO电路保证了LED驱动器在输入电压变化时的可靠性。LED驱动器采用标准的0.5 μm CMOS工艺生产。实验结果表明：LED的亮度可被一个片外的PWM信号调整,在较宽的调光范围内。在全负载变化范围内,电感电流以及输出电流在启动时都平滑上升。当输入电压低于2.18V芯片被锁定,典型的启动时间为137μs。     

基于LLC谐振变换器和准谐振PWM恒流控制的LED驱动电源设计

使用谐振/准谐振拓扑结构设计LED驱动电源,前级DC/DC变换电路采用磁集成的半桥LLC谐振变换器,后级恒流采用准谐振PWM控制的BOOST电路.充分利用谐振BOOST拓扑和LLC谐振变换器的高效率特性,提高电源效率和功率密度.介绍了电路基本结构和工作原理,讨论了两级电路的设计方法.在此基础上制作了样机,实验结果表明所给出的设计方案可行并且合理.     

一种高效率升压型白光LED驱动芯片

设计了一种高效率升压型白光LED驱动芯片,其工作频率恒定为1 MHz。该LED驱动芯片通过调节外部电流感应电阻值来管理输出电流值,以实现恒流驱动。LED驱动芯片采用电流模式的PWM控制方式,具有欠压启动、过压保护、限流保护和温度保护等功能。该升压型白光LED驱动芯片采用CSMC 0.35 μm CMOS工艺实现,启动电压低至0.9 V,静态电流低于0.9 μA,工作效率高达90%。     

利用恒流LED驱动器设计高效率LED照明系统

随着高功率LED的问世,照明产业开始面临新的挑战。LED的使用寿命及电源转换效率成为设计LED照明系统时的主要考虑因素。而为了提供恒流(constantcurrent)以维持LED色彩与亮度的一致性,恒流LED驱动器可作为一个提供恒流输出的开关式转换器。此外,省电或是高效率的电源转换需求更是在LED照明应用上不可缺少的要因,而滞后型脉冲频率调制技术(HystereticPFM)可以大幅提升无论在轻载或重载时的电源转换效率。本文将探讨如何利用恒流LED驱动器设计出高效率、高稳定性的LED照明系统。     

High performance white LED driver with single-wire serial-pulse digital dimming

A high performance white light emitter diode (LED) driver based on boost converter with novel single-wire serial-pulse digital dimming (SWSP) is proposed. The driver uses external serial programmed pulses and internal clock to simplify brightness control. By embedding a 5-bit digital analog converter (DAC) into the driver, wide dimming range is achieved. Moreover, a new dynamic slope compensation circuit is presented and other key circuits of the driver are optimized to get higher efficiency and fast transition response. A practical circuit is implemented with 0.6 um bipolar complementary-metal-oxide-semiconductor double-diffused-metal-oxide-semiconductor (BCD) technology. The simulation results show that the driver can provide both wide output current from 1.3 mA to 42 mA with 32-level digital dimming and higher efficiency up to 83% while it works at 1 MHz switching frequency with the input voltage variation from 2.7 V to 5.5 V.     

高亮LED驱动芯片HV9931的应用

文中介绍了一款高亮LED驱动芯片HV9931,对HV9931的特点及性能作了详细说明,用Cuk变换器为主电路,以HV9931为控制芯片,设计了一款高亮LED驱动电路,给出了实验结果。该电路能在较宽的输入电压范围内保持输出电流的稳定,实现了LED的可靠照明。     

Dynamic performance of maximum power point tracking circuits using sinusoidal extremum seeking control for photovoltaic generation

The article studies the dynamic performance of a family of maximum power point tracking circuits used for photovoltaic generation. It revisits the sinusoidal extremum seeking control (ESC) technique which can be considered as a particular subgroup of the Perturb and Observe algorithms. The sinusoidal ESC technique consists of adding a small sinusoidal disturbance to the input and processing the perturbed output to drive the operating point at its maximum. The output processing involves a synchronous multiplication and a filtering stage. The filter instance determines the dynamic performance of the MPPT based on sinusoidal ESC principle. The approach uses the well-known root-locus method to give insight about damping degree and settlement time of maximum-seeking waveforms. This article shows the transient waveforms in three different filter instances to illustrate the approach. Finally, an experimental prototype corroborates the dynamic analysis.     

Improvements in performance and reliability for segmented linear LED drivers

Several improvements have been made to the conventional segmented linear light-emitting diode (LED) driver topology to enhance the performance and reliability of the system. A compensation technology is proposed to adaptively adjust the impedance of the sensing circuit to keep the output luminance constant in case of line voltage variations. Based on the proposed technology, an active over temperature protection technique is presented to constrain the averaged LED current according to the junction temperature to prevent the driving IC from overheating. Otherwise, a pulse width modulation dimming circuitry which is compatible with input logic level ranging from 1.8 to 20 V is proposed. The proposed technologies are implemented in a 1.0 μm 5/20/500 V BCD technology with three high voltage MOSFETs integrated on chip. The experimental results show that within 220±15% V, 50 Hz AC line-voltage variation, the output luminance is restrained to 4% in total. The output luminance can also be effectively controlled by the PWM dimming circuitry, and a dimming range of 95% is achieved with good linearity.     

高压LED球泡灯的设计与分段优化

近年来在解决以开关电源为基础的传统LED驱动效率低、体积大和成本高等问题的过程中,高压线性分段驱动技术应运而生。为了研究高压线性分段驱动LED球泡灯的设计方法,以高压线性分段驱动芯片SM2087为例,通过实测LED效率得到合适的分段比例为8∶4∶3∶1;并根据该分段比例设计了一种高压LED球泡灯,LED采用COB的方式布置在陶瓷环基板上,散热采用太阳花结构,驱动电路置于灯头内,其具有较高的效率、良好的散热与耐高压能力以及较大的发光角度。     

High-efficiency isolated SEPIC converter with reduced conduction losses for LED displays

This paper proposes a high-efficiency isolated bridgeless single-ended primary inductor converter (SEPIC) for light-emitting-diode (LED) displays. The proposed isolated SEPIC converter can supply LED back-light power with reduced conduction losses. Switching power losses as well as conduction losses are reduced. The proposed converter is theoretically analysed. Experimental results based on a 28 V, 300 W back-light power are discussed to verify the performance of the proposed converter.     

高刷新率LED驱动芯片中PWM控制电路的设计

针对传统LED显示屏刷新率的不足,设计了一种提高LED驱动芯片刷新率的PWM控制电路。将一个刷新周期平均打散分为128段,每段含有256个灰度时钟,占空比由16位灰度数据决定。同时采用基于双边沿触发的灰度计数器,提高了LED显示屏的刷新率,避免画面闪烁。     

LED显示屏实现高质量图像显示的扫描算法分析

介绍了LED显示屏驱动控制模块的原理、接口和性能参数,提出显示屏的屏体分块方法和灰度显示方法,提取了用于显示屏设计中驱动控制方式的若干算法参数,分析并阐明了这些算法参数、显示屏设计要求及驱动模块的性能指标三者之间的关系,并提出了三个设计约束关系式,从而拟定了显示屏的驱动控制方式。该算法在实际产品设计中规范了设计方法,缩短了研发周期。     

一种用于LED驱动控制SOC的线性稳压源

设计了一种用于户外装饰照明类LED驱动控制SOC的线性稳压器LDO,将LED灯使用的12 V~40 V电源电压转换为SOC内部LED显示信号接收电路和LED驱动控制电路使用的5 V电压,并提供正常30 mA、最高100 mA的驱动电流。该LDO的设计基于CSMC 0.5μm 40 V高压BCD工艺在所有工艺角、-55℃~150℃温度范围和12 V~40 V电源电压范围下进行了仿真。结果表明,LDO输出默认情况下电压精度为≤依2.5%,而通过数字控制位Trim<3：1>对LDO的输出电压修正后,LDO输出电压精度可达≤依0.5%,该LDO在所有仿真条件下均可达到设计指标。     

一种原边控制的小功率反激式LED恒流驱动电路

介绍了一种具有功率因数校正功能的原边反激式LED驱动变换器。分析了原边控制的反激式变换器恒流输出的原理与输出电流线性调整率衰退的主要原因;设计了一种自适应的片内功率管关断延时检测与补偿电路,改善了输出电流的线性调整率。设计的单级反激式变换器在90~260 V交流输入电压范围内,功率因数大于0.9,输出功率范围为5~13 W。通过采用改进的峰值电流采样技术与内置自适应关断延时补偿技术,输出电流的线性调整率由23.3%减小到小于1.2%。     

LED负载LLC谐振变换器参数设计

由于LED负载的等效电阻具有可变的特性,传统的电阻负载LLC谐振电路参数设计方法不再适用于LED负载LLC谐振电路参数设计.在电阻负载LLC谐振电路参数设计的基础上,提出一种新的设计方法,使LLC谐振电路在LED负载正常工作范围内满足零电压开关(ZVS);介绍了详细的公式推导和设计过程.基于所提出的方法,以一个谐振频率为100 kHz,额定输入电压为400 V的两路LED灯串为例,给出了设计和仿真结果,验证了新设计方法的可行性.     

自适应神经网络的光电跟踪成像消旋控制系统

为解决机载光电跟踪系统在跟踪过程中由于工作平台框架的转动导致成像画面的旋转问题,提出了一种基于自适应神经网络的消旋控制方法。系统以消旋指令角作为给定位置信息,以光电编码器实测角度值前后两拍之差作为实测速度值,组成速度反馈内环;以陀螺仪测得的角度值作为位置反馈值,构成位置外环;校正算法采用二阶超前-滞后校正并加入了自适应神经网络算法对其控制参数进行自适应调整。实验结果表明,在消旋拍摄过程中,消旋速度满足设计要求,拍摄图片清晰,消旋精度(均方值)达到1.4’,比传统校正方法输出误差减少了46%。     

原边控制带TRIAC调光的LED驱动电源的设计

三端双向可控硅(TRIAC)调光器是目前应用最为广泛的调光器。针对TRIAC调光过程出现的闪烁、调光范围小、效率低等问题,基于FL7730芯片设计一款基于TRIAC调光的原边恒流控制的LED驱动电路;在电路中设计无源泄放电路为TRIAC提供维持电流和擎住电流,避免TRIAC误触发;设计有源阻尼电路抑制调光器导通时产生的尖峰电压。实验结果表明,调光驱动电源的功率因数高于0.9,效率在0.8以上,实现无闪烁调光。     

Slide-mode control scheme with dynamic modifying errors for boost converter

A novel control scheme is presented by using sliding-mode control for boost converter operating in continuous conduction mode (CCM). Although the non-ideal switching condition and physical constraint of the control are considered on the base of equivalent control, the scheme is still simple. By modifying the sliding-modc errors in each switching period, the steady-state errors and chattering can be substantially reduced. Simulation results confirm the theoretical analysis and show the improvement of the converter's start-up behavior and low sensitivity to external perturbation.     

Pseudo-V2 control with adaptive compensation for fast-transient current-mode buck converter

A type of pseudo-V² control, with on-chip adaptive compensation to achieve fast transient (FT) response for current mode DC–DC buck converter, has been proposed and simulated using 0.18 μm CMOS technology in this paper. Based on a new on-chip capacitor multiplier, adaptive compensation is achieved by making the compensation capacitance to track the load current. The proposed pseudo-V² control utilizes the output ripple to determine the duty cycle during load transient. Thus the overshoot/undershoot voltage and the transient recovery time are effectively reduced. Simulation results demonstrate the transient ripple is smaller than 50 mV and the transient recovery time is shorter than 10 μs for a 450 mA load current step. The maximum power conversion efficiency is 94.6% at 1 MHz switching frequency when input and output voltages are 5 V and 1.8 V, respectively.