英文文獻(xiàn) 科技類 原文及翻譯 （電子 電氣 自動(dòng)化 通信…） 1

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1、BALLAST CONTROL IC IR2156(S) 1 Introduction The IR2156 incorporates a high voltage half-bridgegate driver with a programmable oscillator and state diagram to form a complete ballast control IC. The IR2156 features include programmable preheat and run frequencies, programmable preheat time, pro

2、grammable dead-time, and programmable over-current protection. Comprehensive protection features such as protection from failure of a lamp to strike,filament failures, as well as an automatic restart function, have been included in the design. The IR2156 is available in both 14 lead PDIP and 14 lead

3、 SOIC packages. Figure 1 is a block diagram of its internal. Block diagram of the internal IR2156 IR2156 the main features are as follows: ? Ballast control and half-bridge driver in one IC ? Programmable preheat frequency, preheat time, over-current threshold, run frequency and dead time. ?

4、 DC bus under-voltage reset ? Shutdown pin with hysteresis ? Internal 15.6V zener clamp diode on on Vcc ? Micropower startup (150μA) ? Latch immunity and ESD protection Table 1.2 Recommended Operating Conditions Symbol Definition Min. Max. Units Vbs High side floating supply volt

5、age VCC－0.7 Vclamp V Vs Steady state high side floating supply offset voltage －1 600 V VCC Supply voltage Vccuv＋ Vclamp V ICC Supply current 注2 10 mA CT CT lead capacitance 220 —— pF Isd Shutdown lead current －1 1 mA Ics Current sense lead cu

6、rrent －1 1 mA Tj Junction temperature －40 125 ℃ Note 2: Enough current should be supplied into the VCC lead to keep the internal 15.6V zener clamp diode on this lead regulating its voltage, VCLAMP. 2 Functional Description 2.1 Under-voltage Lock-Out Mode (UVLO) The under-vo

7、ltage lock-out mode (UVLO) is defined as the state the IC is in when VCC is below the turn-on threshold of the IC. To identify the different modes of the IC, refer to the State Diagram shown on page 6 of this document. The IR2156 undervoltage lock-out is designed to maintain an ultra low supply curr

8、ent of less than 200uA, and to guarantee the IC is fully functional before the high and low side output drivers are activated. Figure shows an efficient supply voltage using the start-up current of the IR2156 together with a charge pump from the ballast output stage (RSUPPLY, CVCC, DCP1 and DCP2).

9、The start-up capacitor (CVCC) is charged by current through supply resistor (RSUPPLY) minus the start-up current drawn by the IC. This resistor is chosen to provide 2X the maximum start-up current to guarantee ballast start-up at low line input voltage. Once the capacitor voltage on VCC reaches the

10、start-up threshold, and the SD pin is below 4.5 volts, the IC turns on and HO and LO begin to oscillate. The capacitor begins to discharge due to the increase in IC operating current (Figure 2.2). Figure , Start-up and supply circuitry. Figure 2.2, Supply capacitor (CVCC) voltage. During the

11、discharge cycle, the rectified current from the charge pump charges the capacitor above the IC turn-off threshold. The charge pump and the internal 15.6V zener clamp of the IC take over as the supply voltage. The start-up capacitor and snubber capacitor must be selected such that enough supply curre

12、nt is available over all ballast operating conditions. A bootstrap diode (DBOOT) and supply capacitor (CBOOT) comprise the supply voltage for the high side driver circuitry. To guarantee that the high-side supply is charged up before the first pulse on pin HO, the first pulse from the output drivers

13、 comes from the LO pin. During undervoltage lock-out mode, the high- and low-side driver outputs HO and LO are both low, pin CT is connected internally to COM to disable the oscillator, and pin CPH is connected internallyto COM for resetting the preheat time. 2.2 Preheat Mode (PH) The preheat

14、 mode is defined as the state the IC is in when the lamp filaments are being heated to their correct emission temperature. This is necessary for maximizing lamp life and reducing the required ignition voltage. The IR2156 enters preheat mode when VCC exceeds the UVLO positive-going threshold. HO and

15、LO begin to oscillate at the preheat frequency with 50% duty cycle and with a dead-time which is set by the value of the external timing capacitor, CT, and internal deadtime resistor, RDT. Pin CPH is disconnected from COM and Figure 2.3, Preheat circuitry. an internal 5uA current source (Figure )

16、 charges the external preheat timing capacitor on CPH linearly. The over-current protection on pin CS is disabled during preheat. The preheat frequency is determined by the parallel combination of resistors RT and RPH, together with timing capacitor CT. CT charges and discharges between 1/3 and 3/5

17、of VCC. CT is charged exponentially through the parallel combination of RT and RPH connected internally to VCC through MOSFET S1. The charge time of CT from 1/3 to 3/5 VCC is the on-time of the respective output gate driver, HO or LO. Once CT exceeds 3/5 VCC, MOSFET S1 is turned off, disconnecting R

18、T and RPH from VCC. CT is then discharged exponentially through an internal resistor, RDT, through MOSFET S3 to COM. The discharge time of CT from 3/5 to 1/3 VCC is the dead-time (both off) of the output gate drivers, HO and LO. The selected value of CT together with RDT therefore program the desire

19、d dead-time (see Design Equations, page 19, Equations 1 and 2). Once CT discharges below 1/3 VCC, MOSFET S3 is turned off, disconnecting RDT from COM, and MOSFET S1 is turned on, connecting RT and RPH again to VCC. The frequency remains at the preheat frequency until the voltage on pin CPH exceeds 1

20、3V and the IC enters Ignition Mode. During the preheat mode, both the over-current protection and the DC bus under-voltage reset are enabled when pin CPH exceeds 7.5V. 2.3 Ignition Mode (IGN) The ignition mode is defined as the state the IC is in when a high voltage is being established acros

21、s the lamp necessary for igniting the lamp. The IR2156 enters ignition mode when the voltage on pin CPH exceeds 13V. Figure 2.4, Ignition circuitry. Pin CPH is connected internally to the gate of a p-channel MOSFET (S4) (see Figure 2. 4) that connects pin RPH with pin RT. As pin CPH exceeds 13V,

22、 the gate-to-source voltage of MOSFET S4 begins to fall below the turn-on threshold of S4. As pin CPH continues to ramp towards VCC, switch S4 turns off slowly. This results in resistor RPH being disconnected smoothly from resistor RT, which causes the operating frequency to ramp smoothly from the p

23、reheat frequency, through the ignition frequency, to the final run frequency. The over-current threshold on pin CS will protect the ballast against a non-strike or open-filament lamp fault condition. The voltage on pin CS is defined by the lower half-bridge MOSFET current flowing through the externa

24、l current sensing resistor RCS. The resistor RCS therefore programs the maximum allowable peak ignition current (and therefore peak ignition voltage) of the ballast output stage. The peak ignition current must not exceed the maximum allowable current ratings of the output stage MOSFETs. Should this

25、voltage exceed the internal threshold of 1.3V, the IC will enter FAULT mode and both gate driver outputs HO and LO will be latched low. 2.4 Run Mode (RUN) Once the lamp has successfully ignited, the ballast enters run mode. The run mode is defined as the state the IC is in when the lamp arc i

26、s established and the lamp is being driven to a given power level. The run mode oscillating frequency is determined by the timing resistor RT and timing capacitor CT (see Design Equations, page 19, Equations 3 and 4). Should hard-switching occur at the half-bridge at any time due to an openfilament

27、or lamp removal, the voltage across the current sensing resistor, RCS, will exceed the internal threshold of 1.3 volts and the IC will enter FAULT mode. Both gate driver outputs, HO and LO, will be latched low. 2.5 DC Bus Under-voltage Reset Should the DC bus decrease too low during a brown-o

28、ut line condition or over-load condition, the resonant output stage to the lamp can shift near or below resonance. This can produce hardswitching at the half-bridge which can damage the half-bridge switches. To protect against this, pin VDC measures the DC bus voltage and pulls down on pin CPH linea

29、rly as the voltage on pin VDC decreases 10.9V below VCC. This causes the p-channel MOSFET S4 (Figure 4) to close as the DC bus decreases and the frequency to shift higher to a safe operating point above resonance. The DC bus level at which the frequency shifting occurs is set by the external RBUS re

30、sistor and internal RVDC resistor. By pulling down on pin CPH, the ignition ramp is also reset. Therefore, should the lamp extinguish due to very low DC bus levels, the lamp will be automatically ignited as the DC bus increases again. The internal RVDC resistor is connected between pin VDC and COM w

31、hen CPH exceeds 7.5V (during preheat mode). 2.6 Fault Mode (FAULT) Should the voltage at the current sensing pin, CS, exceed 1.3 volts at any time after the preheat mode, the IC enters fault mode and both gate driver outputs, HO and LO, are latched in the 'low' state. CPH is discharged to COM

32、 for resetting the preheat time, and CT is discharged to COM for disabling the oscillator. To exit fault mode, VCC must be recycled back below the UVLO negativegoing turn-off threshold, or, the shutdown pin, SD, must be pulled above 5.1 volts. Either of these will force the IC to enter UVLO mode (se

33、e State Diagram, page 6). Once VCC is above the turnon threshold and SD is below 4.5 volts, the IC will begin oscillating again in the preheat mode. 電子鎮(zhèn)流器控制芯片IR2156 1 引言 IR2156是IR公司最新推出的多功能、低本錢電子鎮(zhèn)流器控制芯片，它由一個(gè)高壓半橋門極驅(qū)動(dòng)器和一個(gè)頻率可調(diào)振蕩器組成。具有預(yù)熱頻率和運(yùn)行頻率可調(diào)，預(yù)熱時(shí)間可調(diào)，死區(qū)時(shí)間可調(diào)，以及過流門限可調(diào)等特性。完善的保護(hù)性能，諸如

34、燈管觸發(fā)失敗保護(hù)，燈絲故障保護(hù)以及自動(dòng)重啟動(dòng)功能都設(shè)計(jì)在其中。IR2156具有DIP14及SOIC14兩種封裝。圖1是其內(nèi)部原理框圖。 圖1.1 IR2156內(nèi)部原理框圖 IR2156的主要特點(diǎn)如下： ???? ●鎮(zhèn)流器控制和半橋驅(qū)動(dòng)器集成在同一片IC中； ???? ●預(yù)熱頻率、預(yù)熱時(shí)間、死區(qū)時(shí)間、同部點(diǎn)火斜坡、工作頻率以及過電流保護(hù)門限等功能或參數(shù)均可編程設(shè)置。 ???? ●具有DC總線欠壓復(fù)位功能； ???? ●具有關(guān)閉腳〔SD腳〕滯后功能，擾噪擾能力強(qiáng)； ???? ●可微功率啟動(dòng)〔150μA〕； ???? ●Vcc腳可被內(nèi)部15.6V的齊納二極管鉗位；

35、 ???? ●全部引腳均具有閉鎖抗噪與靜電放電〔ESD〕保護(hù)功能。 ? 推薦工作條件 符號(hào) 定義 最小值 最大值 單位 Vbs 高端浮動(dòng)供電電壓 VCC－0.7 Vclamp V Vs 高端浮動(dòng)供電偏置電壓 －1 600 V VCC 供電電壓 Vccuv＋ Vclamp V ICC 供電電流 注2 10 mA CT CT引腳電容 220 —— pF Isd 關(guān)斷引線電流 －1 1 mA Ics 電流檢測引線電流 －1 1 mA T

36、j 結(jié)溫 －40 125 ℃ 2 功能及原理 2.1 欠電壓封鎖〔UVLO〕模式 ??? 欠壓關(guān)斷模式是當(dāng)供電電壓VCC低于IC的開啟門限電壓時(shí)，IC不工作。IR2156的欠壓關(guān)斷模式要求供電電流最小保持在200μA以上，保證IC正常工作并驅(qū)動(dòng)上下端輸出。圖2.1為典型的從直流母線饋電和從鎮(zhèn)流器輸出級(jí)充電泵共同為IR2156供電的例子。通過供電電阻(RSUPPLY)的電流一局部作為啟動(dòng)電流流入IC，其余給啟動(dòng)電容(CVCC)充電。電阻應(yīng)能供給兩倍的最大啟動(dòng)電流，以保證鎮(zhèn)流器在低電壓輸入下啟動(dòng)。一旦VCC腳電容電壓到達(dá)啟動(dòng)門限，且SD腳電壓低于4.5V

37、，那么IC開始工作，HO，LO振蕩。由于IC工作電流增大，電容開始放電見圖2.2。 ? IC啟動(dòng)供電方式 ? CVCC電壓 在放電期間，充電泵產(chǎn)生的整流電流給電容充電，使VCC電壓高于IC關(guān)斷門限，充電泵和IC內(nèi)置15.6V穩(wěn)壓管來提供供電電壓。啟動(dòng)電容和緩沖電容要有足夠的容量，使供電電流滿足鎮(zhèn)流器工作需要。自舉二極管〔DBOOT〕和自舉電容〔CBOOT〕提供高端驅(qū)動(dòng)電路的工作電壓。為了在HO腳的第一個(gè)脈沖前就給高端供電，因此輸出驅(qū)動(dòng)的第一個(gè)脈沖來自LO腳。在欠壓關(guān)斷狀態(tài)，高端和低端輸出驅(qū)動(dòng)HO和LO都為低電平，CT腳在內(nèi)部連接到COM使鎮(zhèn)流器停止振蕩，CPH腳在內(nèi)部連接到

38、COM使預(yù)熱時(shí)間位。 2.2 預(yù)熱〔PH〕模式 圖2.3為預(yù)熱電路。預(yù)熱模式工作于燈管燈絲開始加熱直至燈絲到達(dá)正常的點(diǎn)燃溫度，它是延長燈管壽命和降低點(diǎn)燃電壓所必需的步驟。當(dāng)VCC超過UVLO門限時(shí)進(jìn)入預(yù)熱模式。LO和HO開始以50％占空比的預(yù)熱頻率振蕩,死區(qū)時(shí)間由外部定時(shí)電容CT和內(nèi)部死區(qū)時(shí)間電阻RDT決定。CPH腳與COM斷開，內(nèi)部5μA電流源給CPH腳外接的預(yù)熱時(shí)間電容充電。CS腳的過流保護(hù)在預(yù)熱期間被屏蔽掉。 圖2.3 預(yù)熱電路 預(yù)熱頻率由并聯(lián)的電阻RT和RPH，以及定時(shí)電容CT決定。CT分別在到達(dá)〔1/3〕VCC和(3/5)VCC電壓時(shí)充電和放電，R

39、T和RPH并聯(lián)后內(nèi)部連接到VCC，通過MOS管S1對(duì)CT指數(shù)充電〔見圖1.1〕。CT的充電時(shí)間為〔1/3〕VCC至〔3/5〕VCC,分別驅(qū)動(dòng)LO和HO。一旦CT電壓超過〔3/5〕VCC，MOS管S1關(guān)斷，電阻RT和RPH與VCC斷開。CT通過內(nèi)部電阻RDT穿過MOS管S3對(duì)COM以指數(shù)放電。CT的放電時(shí)間為〔3/5〕VCC到〔1/3〕VCC，即輸出門極驅(qū)動(dòng)LO和HO的死區(qū)時(shí)間。CT的容量要根據(jù)RDT和要求的死區(qū)時(shí)間來選取。一旦CT放電至低于〔1/3〕的VCC,MOS管S3關(guān)斷，RDT與COM斷開，MOS管S1導(dǎo)通，RT和RPH連接到VCC。工作頻率始終保持在預(yù)熱頻率直到CPH腳電壓超過13V，

40、IC進(jìn)入觸發(fā)模式。在預(yù)熱模式期間，當(dāng)CPH腳電壓高于7.5V時(shí)，恢復(fù)過流保護(hù)和DC總線欠壓復(fù)位功能。 2.3觸發(fā)〔IGN〕模式 ??? 觸發(fā)電路如圖2.4所示。觸發(fā)模式是指建立觸發(fā)燈管所需的高電壓并觸發(fā)燈管。當(dāng)管腳CPH上的電壓超過13V，IR2156進(jìn)入觸發(fā)模式。 ? 觸發(fā)電路 管腳CPH內(nèi)部連接到一個(gè)P溝道的MOSFET〔S4〕的門極，S4連接管腳RPH和RT。當(dāng)管腳CPH上的電壓超過13V時(shí)，S4的G-S電壓開始低于S4的開通門限。管腳CPH上的電壓持續(xù)向VCC上升，S4緩慢關(guān)斷，這樣就使電阻RPH平滑地從RT上斷開，同時(shí)使工作頻率平滑地過渡到觸發(fā)頻率，再過渡到最

41、終的運(yùn)行頻率。管腳CS的過流保護(hù)功能可以在觸發(fā)失敗或燈絲開路時(shí)保護(hù)鎮(zhèn)流器。外部電流檢測電阻RCS上的電壓即為管腳CS的電壓。RCS定義鎮(zhèn)流器可提供的最大峰值電流〔以及觸發(fā)電壓〕。峰值觸發(fā)電流必須低于MOSFET所能承受的最大電流。當(dāng)CS上的電壓超過內(nèi)部的1.3V門限，IC進(jìn)入故障模式，輸出驅(qū)動(dòng)HO和LO都被鎖定為低電平。 2.4 運(yùn)行(RUN)模式 當(dāng)燈管觸發(fā)成功后，鎮(zhèn)流器進(jìn)入運(yùn)行模式。運(yùn)行模式是指燈弧已經(jīng)建立，燈管以給定的功率工作時(shí)IC所處的狀態(tài)。運(yùn)行模式的振蕩頻率是由定時(shí)電阻RT和定時(shí)電容CT決定的。 2.5 DC總線欠壓復(fù)位 VCC時(shí)，線性拉低管腳CP

42、H電壓，這樣使得P溝道MOSFETS4在DC總線降壓時(shí)開通，并使頻率向上提高到高于諧振點(diǎn)的一個(gè)平安的工作頻率。頻率變化值由外部電阻RBUS和內(nèi)部電阻RVDC決定。通過拉低管腳CPH，觸發(fā)斜率也被復(fù)位。當(dāng)DC總線電壓過低時(shí)，整流器不進(jìn)行觸發(fā)，當(dāng)DC總線電壓再次上升時(shí)，IC將進(jìn)行自動(dòng)再觸發(fā)。當(dāng)CPH上的電壓超過7.5V時(shí)〔預(yù)熱模式期間〕，內(nèi)部電阻RVDC連接到管腳VDC和COM之間。 2.6 故障(FAULT)模式 ??? 在預(yù)熱模式過后的任何時(shí)間，當(dāng)電流檢測腳CS上的電壓超過1.3V時(shí)，IC進(jìn)入故障模式，驅(qū)動(dòng)輸出HO和LO都被置位為低電平。CPH向COM放電，復(fù)位預(yù)熱時(shí)間，同時(shí)CT向COM放電，關(guān)斷振蕩器。要想退出故障模式，VCC電壓必須下降至低于UVLO的下門限，或者關(guān)斷腳SD的電壓拉高至大于5.1V。這兩種方式都可以使IC進(jìn)入U(xiǎn)VLO模式，一旦腳VCC電壓大于開通門限，同時(shí)SD低于4.5V，IC將進(jìn)入預(yù)熱模式開始振蕩。