1、英 文有關(guān)LED照明電源設(shè)計難題的探討 The LED lighting power supply designProblems of design：1. Electrolytic capacitors and LED life issues do not match2. LED燈閃爍的常見原因與處理辦法Common cause of LED lights flashing and approach 3. PWM 調(diào)光對LED的壽命有何影響利用TRIAC調(diào)光調(diào)控LED亮度的潛PWM dimming the impact on the life of LED dimming control4.

2、Using RIAC LED brightness of the potential problems 在LED照明電源設(shè)計中，存在以下幾個設(shè)計難題：電解電容壽命與LED不相匹配、LED燈閃爍的常見原因與處理辦法、PWM 調(diào)光對LED的壽命有何影響、利用TRIAC調(diào)光調(diào)控LED亮度的潛在問題。In the LED lighting power supply design, there are several design challenges: life electrolytic capacitors do not match with the LED, LED lights flashing

3、 common causes and solutions, PWM dimming of the LEDs life impact of the use of TRIAC LED dimming control brightness of the potential problems. ON Semiconductor Senior Application Engineering Manager Cheng were in the text before the occurrence of these problems causes and solution to start on.1.電解電

4、容壽命與LED不相匹配的問題Electrolytic capacitors and LED life issues do not match LED照明的一個重要的考慮因素，就是LED驅(qū)動電路與LED本身的工作壽命應(yīng)該能夠相提并論。LED lighting is an important consideration is the LED drive circuit and the LED itself should be able to compare the work of life. 雖然影響驅(qū)動電路可靠性的因素有很多，但其中電解電容對總體可靠性有至關(guān)重要的影響。Although the

5、reliability of the factors affecting driver circuit a lot, but the overall reliability of electrolytic capacitors have a critical influence. 為了延長系統(tǒng)工作壽命，需要有針對性地分析應(yīng)用中的電容，并選擇恰當(dāng)?shù)碾娊怆娙?。In order to extend the service life of the system, which requires focused analytical applications in capacitors, and sele

6、ct the appropriate electrolytic capacitors.實際上，電解電容的有效工作壽命在很大程度上受環(huán)境溫度及由作用在內(nèi)部阻抗上的紋波電流導(dǎo)致的內(nèi)部溫升影響。In fact, the effective working life of electrolytic capacitors in large part by environmental temperature and the role of the internal impedance of the ripple current caused by impact of the internal temper

7、ature rise. 電解電容制造商提供的電解電容額定壽命是根據(jù)暴露在最高額定溫度環(huán)境及施加最大額定紋波電流條件下得出的。Electrolytic capacitor electrolytic capacitor manufacturers rated life is based on the maximum rated temperature, exposure to the environment and to exert maximum rated ripple current conditions obtained. 在105C時典型電容額定壽命可能是5,000小時，電容所實際遭受的

8、工作應(yīng)力相比額定電平越低，有效工At 105 C rated life of typical capacitance may be 5,000 hours, capacitance compared to the actual working stress suffered by the lower rating level, the more effective long working life. 因此，一方面，選擇額定工作壽命長及能夠承受高額定工作溫度的電解電容當(dāng)然能夠延長工作壽命。Therefore, on the one hand, choose rated long life an

9、d can withstand high operating temperatures of electrolytic capacitors rated to extend the working life of course. 另一方面，根據(jù)實際的應(yīng)力和工作溫度，仍然可以選擇較低額定工作溫度和額定壽命的電容，從而提供更低成本的解決方案；換個角度說，在設(shè)計中考慮保持適當(dāng)?shù)膽?yīng)力和工作溫度，可以有效地延長電解電容的工作壽命，使其更能與LED壽命相匹配On the other hand, according to the actual stress and temperature, you can

10、still choose a lower temperature rating and rating life of the capacitor, thereby providing a more cost-effective solutions; another point of view, a proper consideration in the design of the stress and temperature, can effectively extend the service life of electrolytic capacitors, to better match

11、with the LED lifetime.舉例來說，安森美半導(dǎo)體符合“能源之星”固態(tài)照明標(biāo)準(zhǔn)的離線型LED驅(qū)動器GreenPoint參考設(shè)計選擇了松下的ECA-1EM102鋁電解電容，其額定值為1000 F、25 V、850 mA、2,000小時及85C。For example, ON Semiconductor meet Energy Star standards for off-line-based solid state lighting LED driver GreenPoint reference design chosen Panasonic ECA-1EM102 aluminu

12、m electrolytic capacitor, its rating of 1000 F, 25 V, 850 mA, 2,000 hours and 85 C. 在假定50C環(huán)境溫度條件下，這電容的可用壽命超過12萬小時Assuming 50 C ambient temperature conditions, the capacitance of the useful life over 120,000 hours. 因此，盡力使LED驅(qū)動電路工作在適宜的溫度條件并妥善處理散熱問題，就能實現(xiàn)LED驅(qū)動電路與LED工作壽命的匹配問題。Therefore, strive to make LE

13、D driver circuit in the appropriate temperature conditions and properly handle the heat dissipation, LED driver circuit can be achieved with LED working life of the matching problem.總的來看，如果LED驅(qū)動電路中必須使用電解電容，那就必須努力控制電容所受的應(yīng)用力及工作溫度，從而最大程度延長電容工作壽命，以期與LED壽命匹配；另一方面，設(shè)計人員也應(yīng)該盡可能地避免使用電解電容。In general, if the LE

14、D drive circuit must use the electrolytic capacitor, it must strive to control the application of power capacitors and suffered operating temperature, thus extending the maximum capacitance of working life in order to match with LED life; the other hand, designers should also be possible to avoid th

15、e use of electrolytic capacitors.2.LED燈閃爍的常見原因與處理辦3.Common cause of LED lights flashing and approach通常人眼能夠感知到頻率達(dá)70 Hz的光閃爍，高于這個頻率則不會Usually the human eye can perceive frequencies up to 70 Hz flicker of light, above this frequency will not be perceived.故在LED照明應(yīng)用中，如果脈沖信號出現(xiàn)頻率低于70 Hz的低頻分量，人眼就會感受到閃爍Theref

16、ore, in LED lighting applications, if the pulse signals frequency below 70 Hz low-frequency components, the human eye will feel the flicker. 當(dāng)然，在具體應(yīng)用中，有多種因素可能導(dǎo)致LED燈閃爍Of course, in specific applications, there are several factors that may cause LED light flashes. 例如，在離線式低功率LED照明應(yīng)用中，一種常見的電源拓?fù)浣Y(jié)構(gòu)是隔離型反激拓

17、撲結(jié)構(gòu)For example, in offline LED lighting low-power applications, a common power supply topology is isolated flyback topology. 以安森美半導(dǎo)體符合“能源之星”固態(tài)照明標(biāo)準(zhǔn)的8 W離線型LED驅(qū)動器GreenPoint參考設(shè)計為例，由于反激穩(wěn)壓器的正弦方波功率轉(zhuǎn)換并未給初級偏置提供恒定能量，動態(tài)自供電(DSS)電路可能會激活并引發(fā)光閃爍。ON Semiconductor to meet the Energy Star 8 W solid-state lighting stan

18、dards-based off-line LED driver GreenPoint reference design, for example, because the flyback voltage regulator sine square wave power conversion bias is not to provide a constant primary energy, Dynamic Self-Supply (DSS) circuit may be activated and trigger a flashing light. To avoid this problem,

19、must be made to the initial bias in each half cycle part of the discharge, the corresponding need to properly select the bias circuit constitute the capacitance and resistance value.另外，即使是在使用提供極佳功率因數(shù)校正、支持TRIAC調(diào)光的LED驅(qū)動應(yīng)用中，也要求電磁干擾(EMI)濾波器。In addition, even in the use of power factor correction to prov

20、ide excellent support of TRIAC dimming LED driver applications, also called electromagnetic interference (EMI) filter. 由TRIAC階躍(step)引起的瞬態(tài)電流會激發(fā)EMI濾波器中電感和電容的By the TRIAC step (step) induced transient current EMI filter will stimulate the natural resonant inductor and capacitor. 如果這諧振特性導(dǎo)致輸入電流降至TRIAC維持

21、電流之下，TRIAC將會關(guān)閉If this resonance characteristics lead to reduced input current below the holding current TRIAC, TRIAC will be closed. After a short delay, TRIAC will turn often to stimulate the same resonance. 在輸入電源波形的一個半周期內(nèi)，這系列事件可能會重復(fù)多次，從而形成可見的LED閃爍。In a semi-input power waveform cycle, this series

22、of events may be repeated several times to form the visible LED blinks. To address this problem, TRIAC dimmer is a key requirement is very low input capacitance EMI filter and the capacitor to be able to through the TRIAC and the winding impedance decoupling. 根據(jù) 公式，調(diào)光模塊中電容減小的話，就能夠增大諧振電路的電阻，原理上就抑制振蕩，

23、恢復(fù)想要的電路工作According to the formula, dimming module capacitance decreases, then it can increase the resonant circuit of resistance, on the principle of vibration suppression, restoration of the desired circuit.3.PWM 調(diào)光對LED的壽命有3PWM dimming of the LEDs life impactLED本身的壽命很長，PWM調(diào)光并不會損及LED的預(yù)期壽命；甚至由于PWM調(diào)光幫

24、助減小LED發(fā)熱量，實際上還能幫助延長LED預(yù)期壽命。Its very long life LED, PWM dimming LED will not hurt the life expectancy; even as PWM dimming LED to help reduce the heat, in fact, also help to extend the LED life expectancy. 當(dāng)然，在系統(tǒng)設(shè)計中，需要有效地檢測及控制LED溫度，保證LED可靠工作，體現(xiàn)其長壽命和低維護(hù)成本的優(yōu)勢Of course, in the system design, the need fo

25、r effective detection and control of LED temperature, to ensure reliable operation LED，reflecting its long life and low maintenance cost advantages.4.利用TRIAC調(diào)光調(diào)控LED亮度的潛4LED dimming control using TRIAC brightness of the potential problemsCurrent TRIAC dimming is fairly popular with the market welcome

26、d the dimming mode. TRIAC dimmer originally designed for incandescent lamps, but such as ON Semiconductor has introduced a leading provider of support TRIAC dimming of the LED driver is ideal for LED lighting is provided in the TRIAC dimmer. However, this approach has its limitations lie, such as in

27、creased circuit complexity, affect the power factor; dimming level is relatively limited and so on. ON Semiconductor, as applied to the first green high-performance electronic products, energy efficient silicon solutions provider recently introduced for residential and commercial LED lighting applic

28、ations. This device is using the critical conduction mode (CrM) anti-shock structure of a single-stage topology to provide power factor higher than 0.95,so they save DC - DC (DC-DC) conversion section, simplifying the circuit. This is low even when the device also offers high energy efficiency; comp

29、ly with all regulatory requirements and overall system optical efficiency requirements. In addition, this device is compatible with the front end of TRIAC dimmer and dimmer along the transistor, depending on the use of dimmers, LED light output can be adjusted to less than 2%, providing excellent di

30、mming performance.5. ON Semiconductors LED driver pushing the recent hot program安森美半導(dǎo)體近期推出了幾款重要的高能效GreenPoint LED驅(qū)動器參考設(shè)計，分別是Semiconductor recently introduced several important energy-efficient GreenPoint LED driver reference design is:1) 3W至5 W LED驅(qū)動器參考設(shè)計方案。1) 3W to 5 W LED driver reference design.

31、This reference design for MR16 LED replacement with the size and characteristics of configuration, have been carefully constructed and tested for driving high-brightness LED. 這參考設(shè)計基于降壓-升壓型拓?fù)浣Y(jié)構(gòu)，使用安森美半導(dǎo)體的非隔離型恒流配置、工作在約150千赫茲(kHz)頻率的NCP3065開關(guān)穩(wěn)壓器。This reference design is based on buck - boost topology, u

32、sing ON Semiconductors non-isolated constant current configuration, the work of about 150 kHz (kHz) frequency NCP3065 switching regulator. 這參考設(shè)計電路適合軌道照明、汽車照明及景觀照明等12 Vac或12 Vdc應(yīng)用，不論輸入線路及輸出LED電壓如何變化，均提供平坦的電流穩(wěn)流。This reference design circuit for track lighting, automotive lighting and landscape lightin

33、g, 12 Vac or 12 Vdc applications, regardless of input and output LED line voltage to change, provide a smooth steady flow of current. 這參考設(shè)計還提供獨特的自動檢測電路，支持12 Vdc或12 Vac電源輸入，同時維持目標(biāo)輸出電流。 This reference design also provides a unique auto-detection circuit, supporting 12 Vdc or 12 Vac power input，while m

34、aintaining the target output current. 2) 隔離型8 W恒流LED驅(qū)動器GreenPoint參考設(shè)計方2) Isolated Constant Current LED Driver 8 W GreenPoint reference design. 這參考設(shè)計是為期望符合美國“能源之星”(ENERGY STAR)住宅照明應(yīng)用1.1版固態(tài)照明(SSL)要求的設(shè)計人員而設(shè)，同樣經(jīng)過了精心構(gòu)建及測試，用于驅(qū)動便攜臺燈、櫥柜內(nèi)照明及戶外走廊燈等應(yīng)用中的1到8顆大功率LED。This reference design is expected to meet the U

35、nited States, Energy Star (ENERGY STAR ) residential lighting applications, version 1.1 Solid State Lighting (SSL) requests the designers designed the same have been carefully constructed and tested, used to drive portablelamps,cabinets corridors within the lamps and other lighting and outdoor appli

36、cations in 1-8 high-power LED. 這參考設(shè)計采用新穎的電路配置，無須增加額外的無源功率因數(shù)校正(PFC)網(wǎng)絡(luò)，即可在115 Vac條件下提供高于0.85的功率因數(shù)，減少了元器件數(shù)量，并輕松滿足住宅LED應(yīng)用功率因數(shù)要This reference design uses a novel circuit configuration，without additional passive power factor correction (PFC) network, you can under the conditions provided in the 115 Vac po

37、wer factor above 0.85，reducing component count, and easily meet the residential LED Applications power factor requirements.這設(shè)計支持90 Vac至265 Vac的通用輸入電壓工作，采用安森美半導(dǎo)體集成了固定頻率電流模式控制器和700 V MOSFET的NCP1014開關(guān)穩(wěn)壓器集成電路(IC)。This is designed to support 90 V to265 Vac universal input voltage, using ON Semiconductor

38、integrated fixed-frequency current-mode controller and 700 V MOSFET in the NCP1014 switching regulator integrated circuit (IC).3) 針對離線式高功率因數(shù)TRIAC調(diào)光LED驅(qū)動器的GreenPoint參考設(shè)計。3) High power factor for offline TRIAC dimmer LED driver GreenPoint reference design. 這參考設(shè)計采用了NCL30000這關(guān)鍵器件，旨在用于美國“能源之星”商業(yè)及住宅照明應(yīng)用Th

39、is reference design uses NCL30000 this critical devices， intended for the United States, Energy Star commercial and residential lighting applications. NCL30000工作溫度范圍為-40C至+125C，確保能用于大多數(shù)固態(tài)照明(SSL)應(yīng)用中規(guī)定的不同環(huán)境NCL30000 operating temperature range of -40 C to +125 C, to ensure that for most solid-state lig

40、hting (SSL) applications, the scope of work under different circumstances. NCL30000擁有典型值24微安(A)的低啟動電流及典型值2 mA的低工作電流，配合高能效設(shè)計。NCL30000 has a typical value of 24 microamps (A),low startup current and low typical operating current of 2 mA, with energy-efficient design. NCL30000的其它關(guān)鍵特性包括可編程導(dǎo)通時間限制器、零電流檢測(

41、ZCD)感測模塊、門驅(qū)動器，以及應(yīng)用CrM開關(guān)電源所需的全部其它PWM電路和保護(hù)功能NCL30000 other key features include programmable on-time limiter, zero current detection (ZCD) sensor module, gate drivers, and application CrM switching power supply required by the other PWM circuit and protection.6.安森美半導(dǎo)體LED驅(qū)Semiconductor LED driver desig

42、n advantages安森美半導(dǎo)體提供眾多不同的LED驅(qū)動方案，用于寬廣范圍的應(yīng)用：汽車、移動/便攜(手機和數(shù)碼相機的LCD背光及相機閃光)、中大尺寸的LCD屏幕(筆記本、上網(wǎng)本、液晶電視)的LCD背光、標(biāo)志、建筑物，以及通用照明。ON Semiconductor offers a wide range of different LED-driven programs for a wide range of applications: automotive, mobile / portable (mobile phones and digital cameras, LCD backlight

43、 and camera flash), the large size of the LCD screen (laptop, netbook, LCD TV ) in LCD backlighting, signs, buildings, and general illumination.安森美半導(dǎo)體提供的產(chǎn)品涵蓋3種LED驅(qū)動方法：線性方案(極簡單且極少外部元件)、直流-直流(DC-DC)電感型開關(guān)轉(zhuǎn)換器(用于提供高能效及較大電流)，以及電荷泵開關(guān)轉(zhuǎn)換器(用于提供高能效及緊湊的尺寸)。ON Semiconductors offerings span three kinds of LED dri

44、ving method: linear program (very simple procedure with few external components), DC - DC (DC-DC) inductive switching converter (used to provide energy efficiency and high current) and the charge pump switching converter (used to provide energy efficiency and compact size).總的來看，無論是何種LED照明應(yīng)用，無論需要何種驅(qū)動

45、方案，無論需要何種調(diào)光方法，無論采用何種常見電源電壓供電，安森美半導(dǎo)體均可提供適合的LED驅(qū)動器方案，滿足客戶的不同需求。Overall, no matter what kind of LED lighting applications, no matter what kind driver program, no matter what kind dimming method, regardless of what common power supply voltage, ON Semiconductor may provide a suitable LED driver program t

46、o meet of customers the different needs.7. Current LED lamp features:High-power LED street lamp with conventional high pressure sodium lamps is different is that high-power LED street lamp light source with low voltage DC power supply, power from the GaN-based blue LED and yellow phosphor-based synt

47、hesis of highly efficient white LED, LED (Light Emitting Diode, abbreviated as LED) is based on the formation of semiconductor PN junction with the faint light of the high power solid-state light source can, in certain positive bias voltage and injection current into the P region into the hole and e

48、lectron diffusion region N After the active region to be issued by the radiative photon light energy directly into electrical energy.LED lamp as light source, which compared the traditional lamp light source has many advantages：1. LED Street light, point of itself, does not diffuse light, to ensure

49、optical effect;2. LED lamp has a unique secondary optical design, LED street lamp light shines on the area required for lighting, that is the road to further improve the light efficiency and save energy;3. LED light source efficiency of the current has reached 100lm / W, but there is still much room

50、 for development, the theoretical value can reach 250lm / W. The luminous efficiency of high pressure sodium lamp with the power to increase only increase, and therefore, the overall optical efficiency stronger than the high pressure sodium lamp LED lamps;4.LED street light color rendering than the

51、high-pressure sodium lamp high pressure sodium lamp color rendering index of only 23, while the LED lamp color rendering index can reach 75 or more, from the visual psychological perspective, to achieve the same brightness, LED street lamp illumination average of lower than 20% above the high-pressu

52、re sodium lamp (lighting the light of British standard); and, in the middle of the visual level, the human eye in high color temperature environments with low color temperature than the environment can identify more easily things, to avoid the occurrence of some danger;5. LED street light decline of

53、 small, one-year decline of less than 3% of light, using 10 years of road use is still to achieve illumination requirements, therefore, LED street lamp design, the use of power can be lower than the high-pressure sodium lamp;6. LED lights that automatically adjust light, to achieve different times t

54、o meet the lighting requirements, the maximum possible reduction in power, saving energy;However, recently heard the views of many experts and scholars, that the LED lights to replace high pressure sodium lamp as technically immature. The main reasons are the following:1. LED luminous efficiency and

55、 high-pressure sodium lamp can not be compared2. LEDs light is too concentrated, the poor uniformity of illumination3. LED street light failure severe, life is not long4. LED lamp itself, the excessive weight, not easy installation, wind5. LED lamps and high cost, can not be widelyWe view one by one

56、 according to the above analysis:1. Luminous efficiencyAt present, LED light-emitting efficiency of Looking at the figures do not as high pressure sodium. LED light efficiency is generally 65 75lm / w, but with the technology, LED light effects increased each year, while the high-pressure sodium lam

57、p can reach 125lm / w. However, the high-pressure sodium lamp of the spectrum are relatively concentrated in yellow, it The color temperature is relatively low, only 2000 2500K, and LED color temperature higher than can reach 3500 4500K. Another high pressure sodium light is launched to 4, with much

58、 of the light can not reach the road. Also, high pressure sodium lamp color index is poor, only 23 or so, feeling faint; the LEDs high CRI, can reach 75 to 80. Road bright, comfortable. So from a practical perspective glow, LED but much higher than the high-pressure sodium lamp. The LED can replace

59、250W 135W high pressure sodium lamp, or 300W for mercury. 135W of LED, the output of only about 7020 lumens luminous flux (after the second optical design, will be lost), to reach the road when the number is still 6500 lumens lumens, while the average road surface illuminance can reach 16Lux (12m high pole). 250W high pressure sodium lamp luminous flux output of 20,000 lumens. But the road to reach the number of only 7000 lumens lumens