吉时利_满足高功率、高亮度LED电气测量的需求.pdf

Copyright 2011 Keithley Instruments,Inc.A G R E A T E R M E A S U R E O F C O N F I D E N C EMeeting the Electrical Measurement Demands of High Power,High Brightness LEDs 满足高功率、高亮度满足高功率、高亮度LED电气测量的需求电气测量的需求David WybanKeithley Instruments,Inc.Copyright 2011 Keithley Instruments,Inc.2_ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E议程议程 高亮度高亮度LED vs.高功率高功率LED模块模块(High Brightness LEDs vs.High Power LED Modules)高功率高功率LED模块测试要求模块测试要求(High Power LED Module Testing Requirements)缆线连接考虑缆线连接考虑(Cabling Considerations)晶匣管晶匣管(Thyristors)Copyright 2011 Keithley Instruments,Inc.3_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E高亮度高亮度LED 高亮度高亮度LED通常指功率等于或大于通常指功率等于或大于1W的的LED 通常使用多个高亮度通常使用多个高亮度LED制作照明应用的灯具制作照明应用的灯具 Copyright 2011 Keithley Instruments,Inc.4_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E高功率高功率LED模块模块 通过更小的物理封装获得更高亮度的需求推动了高功率通过更小的物理封装获得更高亮度的需求推动了高功率LED模块的开发模块的开发 高功率高功率LED模块在一个封装内包含了大尺寸管芯模块在一个封装内包含了大尺寸管芯LED和和/或多个或多个LED管芯管芯 多个LED并联或串联连接 Copyright 2011 Keithley Instruments,Inc.5_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E议程议程 高亮度高亮度LED vs.高功率高功率LED模块模块 高功率高功率LED模块测试要求模块测试要求 缆线连接考虑缆线连接考虑 晶匣管晶匣管 Copyright 2011 Keithley Instruments,Inc.6_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E高功率高功率LED模块测试要求模块测试要求测试高功率测试高功率LED模块需要测试具有以下特性的设备：模块需要测试具有以下特性的设备：更高功率更高功率 脉宽调制（脉宽调制（PWM）精密定时精密定时&一致的脉冲宽度一致的脉冲宽度 Copyright 2011 Keithley Instruments,Inc.7_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E更高功率更高功率 直流功率接近直流功率接近100瓦瓦 例子：照明设备例子：照明设备CSM-360 Phlatlight 工作电流为工作电流为63A直流，直流，VF为为14.15V，功率接近，功率接近90W 脉冲功率超过脉冲功率超过100瓦瓦 高功率并且占空比高达高功率并且占空比高达50%例子：照明设备CBT-90 Green Phlatlight 工作电流为22.5A，50%占空比，VF为4.9V，脉冲功率110W Copyright 2011 Keithley Instruments,Inc.8_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E脉宽调制脉宽调制 用于控制亮度的一种方法用于控制亮度的一种方法 LED的驱动电流是脉冲，同时脉冲电平保持恒定的驱动电流是脉冲，同时脉冲电平保持恒定 脉宽调制是通过增加脉宽调制是通过增加/减少导通时间来提高减少导通时间来提高/降低降低LED亮度亮度 Copyright 2011 Keithley Instruments,Inc.9_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EPWM的优点的优点 在在LED的调光过程中保持的调光过程中保持LED色彩一致色彩一致 LED光源的颜色随着电流幅度的改变会有轻微地变化。采用光源的颜色随着电流幅度的改变会有轻微地变化。采用PWM时，时，LED脉冲电流保持恒定所以随着脉冲电流保持恒定所以随着LED亮度减弱亮度减弱LED颜色保持恒定。颜色保持恒定。亮度控制线性度亮度控制线性度 功率效率功率效率 对于所有亮度等级对于所有亮度等级LED都能都工作在最高效的电流幅度（最大流明都能都工作在最高效的电流幅度（最大流明/瓦！）瓦！）在脉冲条件下，在脉冲条件下，LED常常能实现更高的流明常常能实现更高的流明/瓦瓦 开关电路功耗低开关电路功耗低LEDs often produce more Lumens/Watt when pulsed关断时电流几乎为零导通时几乎全部功率送至LED 易于实现并能用便宜的数字电路进行控制易于实现并能用便宜的数字电路进行控制 Copyright 2011 Keithley Instruments,Inc.10_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E脉宽调制的测试设备要求脉宽调制的测试设备要求 脉冲频率达脉冲频率达10kHz 占空比高达占空比高达50%能在每个脉冲上测量能在每个脉冲上测量VF 能触发和响应光谱仪能触发和响应光谱仪 精密定时和一致的脉冲波形精密定时和一致的脉冲波形 Copyright 2011 Keithley Instruments,Inc.11_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EPrecise Timing&Consistent Pulse Shape精密定时精密定时&一致的脉冲波形一致的脉冲波形 脉冲必须具有一致的宽度和形状。脉冲必须具有一致的宽度和形状。保持光谱仪测量的一致性至关重要保持光谱仪测量的一致性至关重要 输出功率输出功率 确保在每个脉冲期间加到确保在每个脉冲期间加到LED的功率相等的功率相等 输入功率输入功率PowerIn 效率的可重复计算非常重要效率的可重复计算非常重要 效率效率=输出功率输出功率/输入功率输入功率 Copyright 2011 Keithley Instruments,Inc.12_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E吉时利吉时利2651A高功率数字源表高功率数字源表 200W直流功率直流功率 高达高达2000W的脉冲功率的脉冲功率 脉宽调制功能脉宽调制功能 在标准直流工作区域内，占空比可设 置为在标准直流工作区域内，占空比可设 置为0100%在在30A条件下，占空比高达条件下，占空比高达50%精密定时和同步至精密定时和同步至500ns 灵活的数字灵活的数字I/O用于触发其它测量仪 器用于触发其它测量仪 器 100nA量程和量程和1pA分辨率分辨率 Copyright 2011 Keithley Instruments,Inc.13_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E议程议程 高亮度高亮度LED vs.高功率高功率LED模块模块 高功率高功率LED模块测试要求模块测试要求 缆线连接考虑缆线连接考虑 晶匣管晶匣管 Copyright 2011 Keithley Instruments,Inc.14_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E缆线连接考虑缆线连接考虑 2线与线与4线（线（Kelvin）连接）连接 缆线电阻过大的影响缆线电阻过大的影响 缆线电感过大的影响缆线电感过大的影响 Copyright 2011 Keithley Instruments,Inc.15_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E2线线vs.4线连接线连接 2线连接线连接 用于源电流的引线同样用于感测电压 测试线上的压降将导致测量的电压大 于器件两端的电压 4线（线（Kelvin）连接）连接 使用单独一对测试线感测器件两端的 电压 电压表是高阻设备，所以通过测试线 的电流几乎为零，因而没有压降 Copyright 2011 Keithley Instruments,Inc.16_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E缆线电阻过大的影响缆线电阻过大的影响 缆线过长会浪费大量功率缆线过长会浪费大量功率 压降可以计算为：V压降=IF*R缆线 在20A情况下，仅200m的缆线电阻将产生4V压降。也就是测试线的功耗达80瓦！存在火灾隐患！在在4线模式下，线模式下，SMU能够补偿的压降是有限的能够补偿的压降是有限的 超过这个限度会使测量不准确 缆线电阻会延长脉冲的上升时间缆线电阻会延长脉冲的上升时间 Copyright 2011 Keithley Instruments,Inc.17_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E缆线电感过大的影响缆线电感过大的影响 缆线电感会抗拒电流变化缆线电感会抗拒电流变化 在脉冲上升沿和下降沿期间测试线上产生压降 电感产生的压降由V=L*di/dt所决定 当电流恒定时，缆线电感不会产生影响 例子：20A脉冲，具有20s上升时间和2H缆线电感。V=2H*20A/20s=2V SMU将尽力补偿缆线电感，但是如果电感过大，脉冲的上升时间和下降时间将 延长将尽力补偿缆线电感，但是如果电感过大，脉冲的上升时间和下降时间将 延长 SMU能补偿的缆线电感大小有限能补偿的缆线电感大小有限 请确保缆线电感低于SMU的最大指标 Copyright 2011 Keithley Instruments,Inc.18_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E最佳缆线连接的技巧最佳缆线连接的技巧 最大程度减小电阻最大程度减小电阻 对于要求的电流幅度总是采用合适尺寸的缆线对于要求的电流幅度总是采用合适尺寸的缆线 例子：例子：20A直流要求直流要求12 AWG或更小或更小 使接触电阻最小使接触电阻最小 保证接头清洁保证接头清洁 确保连接紧固确保连接紧固 确保焊接质量确保焊接质量 使测量仪器和器件之间的接头数量最少使测量仪器和器件之间的接头数量最少 最大程度减小电感最大程度减小电感 通过缠绕测试线形成双绞线，使环路面积最小通过缠绕测试线形成双绞线，使环路面积最小 使用同轴电缆使用同轴电缆 吉时利吉时利2651A高功率数字源表含有低阻、低电感同轴电缆高功率数字源表含有低阻、低电感同轴电缆 电缆额定电阻为每米电缆额定电阻为每米3m和和85nH Copyright 2011 Keithley Instruments,Inc.19_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E议程议程 高亮度高亮度LED vs.高功率高功率LED模块模块 高功率高功率LED模块测试要求模块测试要求 缆线连接考虑缆线连接考虑 晶匣管晶匣管 Copyright 2011 Keithley Instruments,Inc.20_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E晶匣管晶匣管 什么是晶匣管？什么是晶匣管？晶匣管效应晶匣管效应 如何检测晶匣管效应如何检测晶匣管效应 Copyright 2011 Keithley Instruments,Inc.21_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E什么是晶匣管？什么是晶匣管？FF 晶匣管是与晶匣管是与LED结串联的无用电容结串联的无用电容 VF=VLED+VCapacitor Copyright 2011 Keithley Instruments,Inc.22_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E晶匣管效应晶匣管效应 在在VF-IF曲线上，晶匣管表现为一 个曲线上，晶匣管表现为一 个“扭转扭转”在给定在给定IF的条件下，的条件下，LED的的VF比预 计的高比预 计的高 使使LED导通延迟导通延迟IFVFNormalThyristor Copyright 2011 Keithley Instruments,Inc.23_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E检测晶匣管效应检测晶匣管效应 在关断前，晶匣管会出现电压波 形过冲在关断前，晶匣管会出现电压波 形过冲 向向LED施加脉冲电流并采集电压 波形施加脉冲电流并采集电压 波形 调节脉冲正向电流调节脉冲正向电流IF来调整晶匣 管灵敏度来调整晶匣 管灵敏度 在某些电流幅度上，晶匣管最 灵敏在某些电流幅度上，晶匣管最 灵敏 吉时利吉时利2651A高功率数字源表具 有的快速高功率数字源表具 有的快速18bit数字化数字化ADC能采 集此波形能采 集此波形 在测量仪器上可以使用脚本进 行波形分析。在测量仪器上可以使用脚本进 行波形分析。Current Copyright 2011 Keithley Instruments,Inc.24_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E晶匣管的说明晶匣管的说明 取决于温度取决于温度 在较低温度上，晶匣管效应更显著在较低温度上，晶匣管效应更显著 减小热激励更难克服容性壁垒减小热激励更难克服容性壁垒 受环境光线的影响受环境光线的影响 光子激励能轻松克服容性壁垒光子激励能轻松克服容性壁垒 在黑暗环境中更容易检测晶匣管效应！在黑暗环境中更容易检测晶匣管效应！Copyright 2011 Keithley Instruments,Inc.25_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E更多信息更多信息 http:/ http:/ Copyright 2011 Keithley Instruments,Inc.26_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EContact Keithley with Your QuestionsEmail:Tel:[phone]Additional offices:Worldwide Headquarters Within the USA:(+1)888-KEITHLEY Outside the USA:([phone]Asia:China:([phone] Japan:([phone] Korea:([phone] Taiwan:([phone] Copyright 2011 Keithley Instruments,Inc.27_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C E英文原版：英文原版：Meeting the Electrical Measurement Demands of High Power,High Brightness LEDsDavid WybanKeithley Instruments,Inc.Copyright 2011 Keithley Instruments,Inc.28_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EAgenda High Brightness LEDs vs.High Power LED Modules High Power LED Module Testing Requirements Cabling Considerations Thyristors Copyright 2011 Keithley Instruments,Inc.29_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EHigh Brightness LEDs High Brightness LEDs are commonly defined as LEDs that operate at 1W of power or higher Often multiple High Brightness LEDs are put together to create luminaires for lighting applications Copyright 2011 Keithley Instruments,Inc.30_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EHigh Power LED Modules Demand for more light from a smaller physical package has lead to the development of High Power LED Modules High Power LED Modules contain large die LEDs and/or multiple LED die in a single package Multiple LEDs are wired in parallel or in series Copyright 2011 Keithley Instruments,Inc.31_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EAgenda High Brightness LEDs vs.High Power LED Modules High Power LED Module Testing Requirements Cabling Considerations Thyristors Copyright 2011 Keithley Instruments,Inc.32_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EHigh Power LED Module Test RequirementsTesting High Power LED Modules requires test equipment with:More Power Pulse Width Modulation Precise Timing&Consistent Pulse Widths Copyright 2011 Keithley Instruments,Inc.33_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EMore Power DC power approaching 100 Watts Example:Luminus Devices CSM-360 Phlatlight Operates at 6.3A DC with a VF of 14.15V for nearly 90 Watts Pulsed power exceeding 100 Watts High power at duty cycles up to 50%Example:Luminus Devices CBT-90 Green Phlatlight Operates at 22.5A,50%Duty cycle with a VF of 4.9V for 110 Watts Pulsed Copyright 2011 Keithley Instruments,Inc.34_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EPulse Width Modulation Used as a method to control brightness Current to LED is pulsed while pulse level is kept constant Pulse width is modulated to increase/decrease the on time and therefore increase/decrease LED brightness Copyright 2011 Keithley Instruments,Inc.35_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EPWM Advantages Consistent LED color as LED is dimmed The color of the light from an LED changes slightly as the current level changes.In PWM,the LED pulse current is kept constant so LED color is constant as LED brightness is reduced.Brightness control linearity Power Efficiency LED can be operated at its most efficient current level for all brightness levels(Maximum Lumens/Watt!)LEDs often produce more Lumens/Watt when pulsed Switching circuitry wastes little power Nearly zero current flows when switched off Nearly all power is delivered to the LED when switch is on Simple to implement and control with inexpensive digital circuitry Copyright 2011 Keithley Instruments,Inc.36_ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EPulse Width Modulation Test Equipment Requirements Pulse frequencies from up to 10KHz Duty Cycles as high as 50%Ability to measure VF at every pulse Ability to trigger and respond to a spectrometer Precise timing and consistent pulse shape Copyright 2011 Keithley Instruments,Inc.37_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EPrecise Timing&Consistent Pulse ShapePulses must have consistent widths and shapes.Critical in obtaining consistent spectrometer measurements PowerOut Ensures that the same amount of power is being applied to the LED in each pulse PowerIn Critical in making repeatable efficiency calculations Efficiency=PowerOut/PowerIn Copyright 2011 Keithley Instruments,Inc.38_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EThe Keithley Model 2651A High Power SourceMeter Instrument 200 Watts of DC Power Up to 2000 Watts of pulsed power Pulse Width Modulation capability Programmable duty cycle from 0-100%in the standard DC operating areas Up to 50%duty cycle at 30A Precision timing and synchronization to 500ns Flexible digital I/O for triggering other instrumentation 100nA range with 1pA resolution Copyright 2011 Keithley Instruments,Inc.39_ _ _ _ _ _ _ _ _ _A G R E A T E R M E A S U R E O F C O N F I D E N C E|w w w.k e i t h l e y.c o mA G R E A T E R M E A S U R E O F C O N F I D E N C EAgenda High Brightness LEDs vs.High Power LED Modules High Power LED Module Testing Requirements Cabling Considerations Thyr