一個靈活的LED驅(qū)動汽車照明應(yīng)用集成電路設(shè)計和實驗特征畢業(yè)設(shè)計文獻翻譯

1、 畢業(yè)設(shè)計文獻翻譯院系： 電子電氣工程學(xué)院 學(xué) 號： 021309208 姓 名： 吳驍奕 指導(dǎo)教師： 曾國輝 完成時間： 2013/2/15 文獻翻譯021309208 吳驍奕a flexible led driver for automotive lighting applications: ic design and experimental characterization一個靈活的led驅(qū)動汽車照明應(yīng)用:集成電路設(shè)計和實驗特征abstractthis letter presents a smart driver for leds, particularly摘要：這文章提出了一個智能驅(qū)

2、動發(fā)光二極管，for automotive lighting applications, which avoid ringing尤其是用于避免振蕩和超調(diào)現(xiàn)象的汽車照明應(yīng)用上，and overshoot phenomena. to this aim, advanced soft start and為了這個目的，在芯片上集成了優(yōu)化軟啟動和電流升降控制技術(shù)。current slope control techniques are integrated on-chip. this letter這篇文章討論了設(shè)計于集合于高電壓的互補金屬氧化半導(dǎo)體上的驅(qū)動技術(shù)，discusses the driver d

3、esign integrating in high voltage cmostechnology, the digital circuitry for programming and electronic用于編程和電子控制單元連接的數(shù)字電路以及功率元件提高到10瓦特。control units interfacing, and the power devices up to 10w. experimental同時也展示了不同功率等級使用的發(fā)光二極管和與不同類型的連接時的實驗特征。characterizations with leds of different power levels andw

4、ith different types of connections are showed. the smart driver這個智能的驅(qū)動適用于可調(diào)節(jié)的溫度和電壓需求。sustains automotive temperature and voltage requirements; moreover此外，它有很高的功率效率，它是可編程的，還可以配置用于線性的調(diào)節(jié)器。it has high power efficiency, it is programmable, and can beconfigured to work as a linear regulator (for low curre

5、nt leds) orin switch mode (for higher power leds).（用于弱電流發(fā)光二極管）或轉(zhuǎn)換模式（用于高功率發(fā)光二極管）indextermsautomotive electronics, high voltage (hv)cmos,integrated circuit (ic), led driver.關(guān)鍵詞汽車用電子設(shè)備，高電壓互補金屬氧化物半導(dǎo)體，集成電路led驅(qū)動i. introduction1：介紹in the last few years led technology experienced a very fast在過去的幾年中，發(fā)光二極管技術(shù)在

6、汽車照明應(yīng)用中替代普通燈泡經(jīng)歷了一個非?？焖俚倪M步時代，and important growth, superseding the bulb technology inautomotive lighting applications 1. to achieve the harsh requirementof co2 emission and reduce the fuel consumption,car manufacturer must reduce the total power consumption. the為了實現(xiàn)了嚴格的二氧化碳排放要求和降低了燃料的消耗,汽車制造商必須減少總的功率

7、消耗。adoption of leds in place of bulbs permits to have about fivetimes less power consumption at equal output lighting intensity.采用發(fā)光二極管代替燈泡在同等輸出功率照明強度下?lián)p耗將降低五倍。leds have reached quality and reliability factors that permittheir use in automotive harsh environment and in addition發(fā)光二極管已達到質(zhì)量和可靠性因素,可保證他們可

8、使用在汽車的嚴酷環(huán)境下并且他們的成本是降低的。their cost is decreasing. however, leds are pretty difficult to事實上，發(fā)光二極管是很難驅(qū)動，因此相比較普通燈泡，發(fā)光二極管驅(qū)動要求更多的技巧和控制功能。drive and therefore led-drivers require many tricks and controlfunctions compared to bulb drivers. moreover, automotive而且，汽車應(yīng)用程序需要緊湊和低成本的解決方案,靈活足夠的數(shù)字電子控制單元界面， applicatio

9、ns require compact and low-cost solutions, flexibleenough to be interfaced to digital electronic control units (ecu)and to cope with different wiring configurations and relevant同時需要應(yīng)付不同的布線配置和相關(guān)拓展。parasitics 2. automotive lighting systems should be also robust汽車照明系統(tǒng)也應(yīng)該對電磁干擾(emi)和超溫、過流以及過電壓現(xiàn)象有應(yīng)變能力。wit

10、h respect to electromagnetic interference (emi) andto overtemperature, overcurrent, and overvoltage phenomena,such as those due to ringing effects generated by resonance of例如那些由于激振效應(yīng)所產(chǎn)生的共振的線電感和連接器電容。wire inductance and connector capacitance. usually, in car environment通常,在汽車環(huán)境中，幾米長電線使用,就會生成強烈振蕩。few

11、meters long wires are used, generating dumpedoscillations. such oscillations and the associated overcurrentand overvoltage levels reduce the led life time and its efficiency這種振蕩和與之相關(guān)的過電流和過電壓會降低發(fā)光二極管壽命及其效率。3. to avoid or limit these effects the led cannot bedriven by a mechanical relay but a smart dr

12、iver is required tocontrol the slope of the led current during transient, keeping it為了避免或限制這些影響發(fā)光二極管不能由一個機械繼電器控制但智能的驅(qū)動被要求需要在瞬態(tài)控制led電流的斜率，以保持它在電線的特征頻率以下。below the characteristic frequency of the wire. a compact andefficient led driver is needed, overcoming the above issues andfeaturing a high flexibi

13、lity to face different led power levels,一個緊湊和高效的led驅(qū)動程序是必要的,是為了克服上述問題和具有高靈活性，去面對不同的發(fā)光二極管功率級別，連接拓撲和電線寄生。connections topology, and wiring parasitics. hereafter, section此后，在第二部分，分析了振蕩和電磁干擾在放光二極管驅(qū)動中的影響。ii analyzes ringing and emi problems in led driving. sectioniii presents the design of the new led sma

14、rt driver focusing on第三部分介紹了一款新設(shè)計的智能發(fā)光二極管驅(qū)動的顯著特征。its distinguishing features. section iv presents its experimental第四部分介紹了發(fā)光二極管在不同功率等級下的實驗特征，從幾十毫瓦特characterization with leds of different power levels, from tensof milliwatts to several watts, used stand-alone, or connected in到幾瓦特在獨立或幾個連接下的狀態(tài)。strings.

15、temperature and voltage range operating conditions are溫度和電壓等級的工作條件也被測量判斷。also measured. conclusions are drawn in section v.第五部分將引出結(jié)論。ii. ringing and emi problems in led driving二.振蕩和電磁干擾在發(fā)光二極管驅(qū)動中的影響at state-of-the-art led, driving is implemented using lowdropout linear regulators, which are limited t

16、o leds of few tensof milliamperes, or more power-efficient switching solutions athigher current levels 在最開始的led,開車是使用低輸出線性穩(wěn)壓器,僅限于幾十毫安級的發(fā)光二極管,或更省電轉(zhuǎn)換解決方案用在更高的電流水平。310. however, a compact solution integrating然而,一個緊湊的集成解決方案在一個單芯片數(shù)字ecu接口,on a single chip a digital ecu interface, a low-powerconfigurable l

17、ogic core, a power part able to work in linear modeor switching one, as well as advanced techniques such as softstart and current slope control, has not been proposed yet in一個低功耗可配置的邏輯核心,電源部分能夠工作在線性模式或轉(zhuǎn)換它,以及先進的技術(shù),如軟開始和電流升降調(diào)節(jié)，還沒有在文獻中被提出。the literature. the main difficulties in the design of a univers

18、al設(shè)計一個足夠的靈活的發(fā)光二極管驅(qū)動應(yīng)用在不同的接線配置最大的難題是振蕩和電磁干擾問題。led driver, flexible enough to be applied to different wiringconfigurations, are the ringing and emi issues. these problems這些問題取決于環(huán)境因素和寄生組件，這些因素很難去假設(shè)和模仿。depend on environmental and parasitic components that are difficultto predict and simulate.while bulbs

19、 are easily modeled as而電燈泡卻很容易模仿因為它有線性的正溫度系數(shù)并且寄生成分對它的影響比較小。linear positive temperature coefficient (ptc) resistors, and areless sensitive to parasitic components, a led is a special diode發(fā)光二極管是一種特殊的二極管，它滿足肖克利指數(shù)電流-電壓法。and follows the shockley exponential iv law. a very smallfluctuation on the voltage

20、 across the led can generate a very一個很小的電壓起伏通過發(fā)光二極管可能引起一個很大的電流變化影響。high variation on its current affecting, as proved in 3, both efficiency經(jīng)證明，效率和照明設(shè)備的壽命都將被影響。and life time and creating lighting disturbs. this behavior如果發(fā)光二極管沒有恰當(dāng)?shù)谋或?qū)動的話這個行為會導(dǎo)致振蕩和高強度的電流尖脈沖。can generate ringing and high current spikes

21、if the led is not properly driven. by the same token, a bulb-designed driver, as出于同樣的原因，燈泡的驅(qū)動，正如10-12中說的，不能被直接用于驅(qū)動發(fā)光二極管。shown in 1012, cannot be directly used to drive efficientlyleds. this is particularly true when the led and the driver are這一點是完全正確的當(dāng)發(fā)光二極管和驅(qū)動在汽車連接中被幾米的電纜分割的時候。separated by a few met

22、er cables as in automotive connections.in this case, the wiring parasitics can generate ringing and emi.出于這個原因，電線的寄生將引起振蕩和電磁干擾。a comparison based on experimental measurements, between一個在二瓦特的燈泡和0.1瓦特的連著很短的線（大概10厘米長）發(fā)光二極管的比較實驗中顯示在圖1和圖2中。a 2-w bulb lamp and a 0.1-w led turn-on transient with veryshort

23、wire (about 10 cm long) and with very long wire (about3m long) is shown, respectively, in figs. 1 and 2. a simplerelay is used as a switch to highlight the different behavior一個簡單的繼電器被用來切換到這些負載不同的狀態(tài)。of those loads. those pictures show the necessity of using a這些圖片展示了使用一個設(shè)計良好的led驅(qū)動從而避免寄生電路的重要性。well-des

24、igned driver for leds, to avoid unwanted effects dueto wiring parasitics. in fact, the behavior of the current in the事實上，燈泡的電流狀態(tài)不隨著線的長度而變化。從圖1a圖2a可以看出bulb does not change significantly with the wire length seefigs. 1(a) and 2(a) while the transient of the current in the而發(fā)光二極管的瞬間電流缺有顯著的差異。從圖1b和2b可以看出

25、led shows significant differences see figs. 1(b) and 2(b). toovercome this issue we propose a compact solution, integrating為了解決這個問題我們計劃了一個簡潔的方案：in 0.35-mhvcmostechnology the digital circuitry for driverinterfacing/configuration and power devices up to 10w, with采用高壓cmos技術(shù)數(shù)字電路的驅(qū)動程序，接口/配置和功率設(shè)備提高到10 瓦特h

26、v protection up to 55v. the led driver can be interfaced to同時高壓保護提高到55伏特。led驅(qū)動可以被顯示到數(shù)字電子控制單元，digital ecu 1315 and is able to cope with different wiring從而它可以處理各種長度的電線配置和寄生電路。configurations some meters long and their parasitics 2, and to使其適應(yīng)作為線性穩(wěn)壓器和開關(guān)的表現(xiàn)，取決于編程的精度。adapt its behavior working as linear r

27、egulator or as a switchingone, depending on a programmable threshold.iii. flexible led driver ic三. 靈活的發(fā)光二極管驅(qū)動集成電路with respect to the bulb lamp driver shown in 11, 12 the關(guān)于指示燈驅(qū)動器了，智能led驅(qū)動必須滿足嚴酷的汽車環(huán)境約束。smart led driver needs to fulfill the same harsh automotive environmentconstraints, as well as more

28、power demanding loads,同時也要滿足更多的功率負載需求用于串聯(lián)和并聯(lián)配置下的發(fā)光二極管。as series and parallel configuration of leds. low power leds,like those employed in the car dashboard, absorbing 3050mw,像那些30-50毫瓦的用于汽車儀表盤的低功率發(fā)光二極管，包括那些排列在一起的總功率到10瓦特的發(fā)光二極管或燈泡，能被提議的設(shè)計驅(qū)動。as well as arrays of power leds or lamps up to 10w, can bedr

29、iven properly by the proposed design. 圖1.（a）燈泡（b）發(fā)光二極管 在沒有任何電流電壓控制的10厘米電纜下狀態(tài)圖2 （a）燈泡（b）發(fā)光二極管 在沒有任何電流電壓控制3厘米電纜下狀態(tài)圖3. 方案一允許的負載配置,加強了布線寄生現(xiàn)象,發(fā)光二極管,和串聯(lián)的電池中的開關(guān)。圖4.led驅(qū)動集成電路的體系結(jié)構(gòu)和詳細電路the driving of leds has required the implementation of specific techniques to limit the undesired effects of wiring parasiti

30、cs, 發(fā)光二極管的驅(qū)動要求實施特定的技術(shù)來限制布線寄生現(xiàn)象帶來的不良影響。such as ringing andconsequent overshoots and undershoots如振蕩和隨之引起的超調(diào)量和脈沖信號。.in fig. 3, the scheme of the wiring parasitic and of a possible connection betweenthe driver and the load is shown: the output pin of the driver,在圖三中，該計劃的布線寄生和可能的在驅(qū)動和負載的連接中顯示:輸出的驅(qū)動程序，其功能可

31、以用一個簡單的開關(guān)描述，是連接發(fā)光二極管，并且和汽車的whose functionality can be represented by a simple switch tothe ground, is connected to a led, in series with the car batteryand another switch, controlled by the user through a button or電池和另外一個開關(guān)連接，而用戶通過一個按鈕或點火鑰匙來控制它。the ignition key. the basic scheme of the flexible led

32、driveris shown in fig. 4, together with circuit details of the operational這個靈活的發(fā)光二極管驅(qū)動基本方案以及電路詳細的步驟和跨導(dǎo)放大器塊如圖四所示。transconductance amplifier (ota) block: the architecture這個設(shè)計基于一個is based on a voltage regulation loop inserted inside a linear loopproviding the current control capability.插入在一個線性循環(huán)的電壓調(diào)節(jié)回路

33、以提供當(dāng)前的控制能力。the voltage regulationloop forces the output on a reference voltage, vref , when 電壓調(diào)節(jié)回路控制輸出的是參考電壓當(dāng)?shù)蛪簻y主電源開關(guān)串聯(lián)二極管以提供反極性的容量給裝置，是開啟了。the low side main power switch (power mos in fig. 4), in series withthe diode that provides reverse polarity capability to the device,is turn on. the led driver

34、 has been integrated as hard macrocellled驅(qū)動程序已經(jīng)被集成在一個復(fù)雜的大容量的電池汽車控制單元集成電路中in a complex automotive control unit ic, implemented inaustria micro systems (ams) 0.35 m cmos technology. fig 5被用在ams0.35um的互補金屬氧化物半導(dǎo)體技術(shù)中。從圖5中可以看出，shows the layout and the photo of the whole control unit ic,布局和圖片的整個控制單元集成在電路中，

35、使得發(fā)光二極管驅(qū)動電子電路增強。highlighting the led driver circuit, and particularly the powermos and its protection diode in fig. 4, which occupy most ofthe led driver area.特別的在圖四中的mos材料和二極管的保護，占絕了絕大部分的發(fā)光二極管驅(qū)動電路。by regulating the output voltage on a reference level the stateof the load and of the power switch can

36、 be easily detected.通過調(diào)節(jié)輸出電壓在一個參考電平狀態(tài)的負載和電源開關(guān)可以很容易地被檢測到。when the led is on (user switch and power switch in fig. 3當(dāng)發(fā)光二極管打開，（用開關(guān)或者圖3的電源開關(guān)都可以使運轉(zhuǎn)）both enabled), the regulation loop is activated and the output調(diào)節(jié)回路是激活的，輸出電壓是控制為參考電壓的。vo is forced on the reference voltage, vref . if the user switch同時強制發(fā)光二極

37、管也關(guān)閉，如果關(guān)閉開關(guān),因此發(fā)光二極管也關(guān)閉is off, and hence also the led is off, the output pin of thedriver is pulled down even when the power switch is off, by輸出引線驅(qū)動被損壞甚至電源總開關(guān)也關(guān)掉，意味著編的程序沒有應(yīng)變能力。means of a programmable resistive path to ground. that pathis highly resistive to limit to very low value the current flowing

38、through the led. finally, if the user switch is on but the這條道路的高電阻是用來限制非常低的電流來通過發(fā)光二極管，如果用戶開關(guān)打開但電源開關(guān)關(guān)閉，那么輸出電壓將強迫輸出為電源的額定電壓。power switch is forced off, then the output vo is pulled up tothe battery voltage, vbatt , and the led is off since no noticeable發(fā)光二極管也將關(guān)閉直到?jīng)]有明顯的電流通過。current is flowing. summariz

39、ing, depending on the statusof the switch devices in fig. 3, the output voltage vo can bepulled down to ground, or pulled up to vbatt or forced to vref .根據(jù)不同開關(guān)設(shè)備的狀態(tài)，如圖3所示,輸出電壓可以接地,或者強迫為電源的額定電壓。a comparator can reveal the status of the driver and also potentialovervoltage conditions by comparing the

40、output voltageto proper thresholds. similarly overcurrent and overtemperature一個比較器可以顯示驅(qū)的狀態(tài)和通過比較輸出電壓合適的閾值看出潛在的過壓條件。phenomena can be detected by comparing the measured currentand temperature values (through an on-chip temperature sensor)with proper thresholds. all reference and threshold levels are同樣的

41、過電流和超溫現(xiàn)象是可以探測到的測量的電流和溫度的值(通過一個芯片上的溫度傳感器)和適當(dāng)?shù)拈撝当容^。internally generated by a digital-programmable band-gap unit.所有的引用和閾值水平是由內(nèi)部產(chǎn)生的數(shù)字通過可編程的帶隙裝置。the measurements shown in this letter are obtained with a vref這篇文章中的測量值是通過額定電壓獲得，1.2伏特。of 1.2v. the detected driver and load status are used by theinternal logi

42、c as feedback signals to properly drive the powermos in fig. 4, acting as linear regulator or onoff switch,檢測到的驅(qū)動和負載狀態(tài)使用內(nèi)部邏輯作為反饋信號正確驅(qū)動動力在圖四中的金屬氧化物半導(dǎo)體,是作為線性調(diào)節(jié)器或開關(guān)and implementing advanced soft start or current slope control techniques.和實施先進的軟啟動或電流升降控制技術(shù)the working mode of the led driver, as linear re

43、gulator oronoff switch, is determined by the user by proper configuringthe current level iref in fig. 4. the mosma mirrors a small工作模式的led驅(qū)動,線性調(diào)節(jié)器或通斷開關(guān),是由用戶通過適當(dāng)?shù)呐渲迷趫D4按圖四的電流是水平。fraction of the power mos output current and, through the hvand low-voltage (lv) current mirrors in fig. 4, mosma反射小部分功率從mos

44、輸出電流,如圖四通過高壓和低壓(lv)電流反射鏡鏡，compares it to the iref current value (generated through on-chip band-gap circuit).比較其當(dāng)前值(通過芯片上的帶隙電路生成iref)。the hv pmos current mirror is connected to the outputvoltage, which is up to 12v, while the lv pmos current mirroris connected to vdd = 3.3v. the difference between i

45、mir and高壓pmos的電流反射連接到輸出電壓提高到12伏特,而低壓pmos電流反射連接到vdd是3伏特。iref drives the gate of mos mb : if imir is lower than iref , thenimir和iref之間的在mos驅(qū)動上的區(qū)別是：如果imir低于irel，那么mb是關(guān)閉的mb is off and the power mos, driven by the ota in fig. 4,并且mos的能量是由如圖四中的ota驅(qū)動的，通過線性的電流調(diào)節(jié)器。acts as a linear current regulator. otherwis

46、e, mb is on and the反之，如果mb是打開的而電流環(huán)路控制開關(guān)關(guān)閉，那么mos mb將會被強制關(guān)閉。current loop control switches to the off state the power mos.the mos mb can be forced back in off state, and hence the同時強制電源mos起作用，如圖四用來進行邏輯控制。powermos reactived, by the control logic in fig. 4. the controllogic determines the times ton and t

47、off when mb is off (i.e.,這個控制邏輯決定什么時候開什么時候關(guān)分別當(dāng)mb關(guān)掉的時候（mos開著）power mos is on) or mb is on (i.e., power mos is off), respectively.或者mb開著（mos關(guān)閉）in this case, the driver is working in onoff switch因此，這個驅(qū)動工作在關(guān)或開的模式為了滿足控制邏輯不停的變換開關(guān)。mode with duty cycle and frequency depending on the ton andtoff times set by

48、 the control logic.summarizing, in linear regulator mode iref is configured sothat the current loop control is activated only for output currentsof several amperes, much higher than the operating load currents總結(jié),在線性調(diào)節(jié)器模式iref是如此配置的為了電流環(huán)路控制輸出電流只有安培。foreseen for this led driver (see section iv). in lin

49、ear mode,遠高于操作負載電流的led驅(qū)動程序(見第四部分)。在線性莫模型中，iref acts as a protection threshold: if imir is over iref then mb isiref擔(dān)當(dāng)著一個保護的臨界值：當(dāng)imir超過了iref，那么mb會打開，電源mos會關(guān)閉。switched on and the power mos is switched off.in on/off switching mode, iref is configured at levels lower在開/關(guān)模式下，iref是按從低到高電流等級配置的。than normal

50、operating currents: the power mos is no directlydriven by the ota and the combined action of the current loopcontrol and of the control logic on the mos mb determines theton and toff periods (and hence the switching duty cycle andfrequency) of the power mos. to be noted that in switching電源mos沒有直接被ot

51、a和聯(lián)合作用的電流環(huán)路控制。同時控制邏輯在mos mb上決定了開或者關(guān)的周期(因此切換工作周期和頻率)。mode iref is not acting as the sole current limitation level; thedetection of overcurrent phenomena is carried out by the over-i and over-v detect block in fig. 4. the described approach注意,在切換模式iref不是作為唯一的電流限制水平;檢測過流現(xiàn)象是被運用于過壓過流檢測塊,如圖4所示。allows to i

52、mplement two functions in the same led driver ic atminimal hardware overhead: linear regulator mode, useful for所述方法可以實現(xiàn)兩個功能相同的led驅(qū)動集成電路在最小的硬件開銷:線性穩(wěn)壓器，用于瞬間的變化和低電流低功率led，當(dāng)電源效率不是問題的時候。fast transient and low-current/low-power leds, where powerefficiency is not an issue; switch driving mode, useful for h

53、igher開關(guān)驅(qū)動方式，用于高電流和高功率led，當(dāng)電源效率是關(guān)鍵問題所以current and higher power leds where the power efficiency is akey issue and therefore a switching regulator has to be preferredto a linear one.線性的開關(guān)穩(wěn)壓器將被成為首選。the driving of a led calls also for specific strategies toavoid the ringing phenomenon on the connecting w

54、ire withthe consequent current overshoot. the soft start and current發(fā)光二極管的驅(qū)動也要求具體策略在連接線上避免振蕩現(xiàn)象與隨之產(chǎn)生的電流超調(diào)。slope control techniques, proposed by the authors in 12 forbulb lamp driving (low-power dashboard indicator), have beenimproved to maintain the same proper behavior also with arraysof leds and hi

55、gh luminosity up to 10w. the design has taken軟啟動和電流斜率控制技術(shù),作者在12中提出的燈泡驅(qū)動(低功耗儀表板指示器),被用來保持適當(dāng)?shù)臓顟B(tài)，同時也排列二極管把光度提高到10瓦特。into account the variability of parasitic capacitors and inductors,設(shè)計已經(jīng)考慮到可變性的寄生電容和電感,as well as of the load and all process-voltage-temperature (pvt)以及負載和所有過程電壓溫度(pvt)的部分。corners. as sho

56、wn in fig. 6, by sweeping through different如圖六所示，通過不同的布線寄生現(xiàn)象和等效電阻對不同負載配置的發(fā)光二極管，values of the wiring parasitics and of the equivalent resistancefor different led-based load configurations, the phase margin電壓調(diào)節(jié)回路的相位補角,如圖4所示，在一個相關(guān)的方式下變化。of the voltage regulation loop in fig. 4 changes in a relevantway.as a consequence, the susceptibility to instability of the overall因此，circuit varies, along with the entity of the ringing, as illustrated不穩(wěn)定的磁感系數(shù)的整體電路的變化,隨著實體振蕩，在圖7中闡述的那樣。in