TWI445443B

TWI445443B - Control circuit and control method for dimming led lighting circuit

Info

Publication number: TWI445443B
Application number: TW100130696A
Authority: TW
Inventors: Ta Yung Yang; Li Lin; Chi Yin Lo; Kuo Hsien Huang; Hung Chun Chen
Original assignee: System General Corp
Priority date: 2011-08-26
Filing date: 2011-08-26
Publication date: 2014-07-11
Also published as: TW201311033A

Description

調光發光二極體照明電路的控制電路及控制方法Control circuit and control method of dimming light emitting diode lighting circuit

本發明關於一種發光二極體(Light Emitting Diode，LED)照明電路，特別關於一種用於LED調光照明電路的控制電路與控制方法。The invention relates to a light emitting diode (LED) lighting circuit, in particular to a control circuit and a control method for an LED dimming lighting circuit.

圖1繪示傳統調光照明電路100的電路圖。此調光照明電路100基本上包括一雙向閘流體(TRIAC)110、橋式整流器120以及一負載130。此TRIAC 110接收一交流電流(alternating current，AC)源V_AC 。藉由控制TRIAC 110的閘極(gate)電壓，來自交流電流源V_AC 的功率可經由橋式整流器120提供至負載130，例如電燈泡，以達到調光控制。FIG. 1 is a circuit diagram of a conventional dimming lighting circuit 100. The dimming lighting circuit 100 basically includes a bidirectional thyristor (TRIAC) 110, a bridge rectifier 120, and a load 130. The TRIAC 110 receives an alternating current (AC) source V _AC . By controlling the gate voltage of the TRIAC 110, power from the alternating current source V _AC can be provided to the load 130, such as an electric bulb, via the bridge rectifier 120 to achieve dimming control.

然而，為了使TRIAC 110的狀態保持在導通狀態，需要一最小維持電流。也就是說，流經TRIAC 110的電流I_AC 應該被保持在高於TRIAC 110的最小維持電流的狀態，否則TRIAC 110將變換為截止狀態。然而，提供至負載130的負載電流I_LD 的準位相同於電流I_AC 的準位。如此一來，負載電流I_LD 需要滿足TRIAC 110的最小維持電流的需求；否則，若負載130是一電燈泡，且電燈泡亮度較暗時(也就是流經負載130的負載電流I_LD 較小，並低於TRIAC 110的最小維持電流)時，則TRIAC 110將處於介於導通與截止的不穩定狀態，進而導致燈光閃爍。However, in order to maintain the state of the TRIAC 110 in an on state, a minimum holding current is required. That is, the current I _AC flowing through the TRIAC 110 should be maintained above the minimum sustain current of the TRIAC 110, otherwise the TRIAC 110 will transition to the off state. However, the level of the load current I _LD supplied to the load 130 is the same as the level of the current I _AC . As such, the load current I _LD needs to meet the minimum sustain current requirement of the TRIAC 110; otherwise, if the load 130 is a light bulb and the light bulb is dark (ie, the load current I _LD flowing through the load 130 is small, and Below the minimum holding current of TRIAC 110, the TRIAC 110 will be in an unstable state between on and off, which will cause the light to flicker.

因此，如何設計出簡單的控制電路與方法，使得燈泡處於微弱亮度狀態時，其燈光不會閃爍，實為目前研究發展的一重要方向。Therefore, how to design a simple control circuit and method, so that when the bulb is in a weak brightness state, its light will not flash, which is an important direction of current research and development.

本發明關於一種用於LED調光照明電路的控制電路與控制方法，其具有簡易的組成元件，藉由第一電晶體聯同一泄流電阻根據一控制信號從一輸入端抽取一泄流電流，如此TRIAC的狀態可保持在導通狀態，進而避免燈泡燈光閃爍。The invention relates to a control circuit and a control method for an LED dimming lighting circuit, which has a simple component, and a first bleeder is connected to the same bleeder resistor to extract a bleed current from an input terminal according to a control signal. Thus the state of the TRIAC can be kept in a conducting state, thereby preventing the bulb light from flashing.

根據本發明的一方面，提供一種用於LED調光照明電路的電路。此電路包括一分壓器、一控制器以及一可調適泄流器。此分壓器接收來自一輸入端的一輸入電壓以產生一調光信號。此控制器根據該調光信號以產生一切換信號，其中該控制器還根據該輸入電壓產生一控制信號。可調適泄流器接收該控制信號並根據該控制信號從該輸入端抽取一泄流電流。According to an aspect of the present invention, an electric circuit for an LED dimming lighting circuit is provided. The circuit includes a voltage divider, a controller, and an adjustable bleeder. The voltage divider receives an input voltage from an input to generate a dimming signal. The controller generates a switching signal according to the dimming signal, wherein the controller further generates a control signal according to the input voltage. The adjustable bleeder receives the control signal and draws a bleeder current from the input based on the control signal.

根據本發明的另一方面，提供一種用於LED調光照明電路的控制方法，包括下列步驟：藉由一分壓器根據一輸入電壓從一輸入端產生一調光信號；藉由一控制器各別地根據該調光信號與該輸入電壓以分別產生一切換信號與一控制信號；藉由第二電晶體箝制所述第一電晶體的一最大操作電壓；以及藉由一可調適泄流器根據該控制信號以從該輸入端抽取一泄流電流。According to another aspect of the present invention, a control method for an LED dimming lighting circuit is provided, comprising the steps of: generating a dimming signal from an input terminal according to an input voltage by a voltage divider; Separately generating a switching signal and a control signal according to the dimming signal and the input voltage; clamping a maximum operating voltage of the first transistor by the second transistor; and adjusting the drain by an adjustable voltage The device extracts a bleeder current from the input terminal according to the control signal.

為使本發明的上述內容能更明顯易懂，下文特舉本發明較佳實施例，並配合附圖，作詳細說明如下：In order to make the above description of the present invention more comprehensible, the following detailed description of the preferred embodiments of the invention,

為使本發明之上述目的、特徵和優點能更明顯易懂，下文特舉一較佳實施例，並配合所附圖式，作詳細說明如下。The above described objects, features and advantages of the present invention will become more apparent from the description of the appended claims.

圖2是根據本發明繪示用於LED調光照明電路的一實施例。用於LED調光照明電路的控制電路200包括一分壓器210、一控制器220以及一可調適(adaptive)泄流器230。於一實施例中，控制電路200可還包括一雙向閘流體(TRIAC)240、橋式整流器(bridge rectifier)250、功率電晶體260以及一負載270。2 is an illustration of an embodiment of an LED dimming lighting circuit in accordance with the present invention. The control circuit 200 for the LED dimming lighting circuit includes a voltage divider 210, a controller 220, and an adaptive bleeder 230. In an embodiment, the control circuit 200 can further include a bidirectional thyristor (TRIAC) 240, a bridge rectifier 250, a power transistor 260, and a load 270.

分壓器210，是藉由串連電阻211與212所形成，接收一輸入電壓V_IN 以在電阻211與212的接點根據此輸入電壓V_IN 產生一調光信號S_DM 。於一實施例中，分壓器210可還包括一電容213，其中此電容213可被用於將調光信號S_DM 平順為一直流準位。The voltage divider 210 is formed by the series resistors 211 and 212, and receives an input voltage V _IN to generate a dimming signal S _DM according to the input voltage V _IN at the junction of the resistors 211 and 212. In one embodiment, the voltage divider 210 can further include a capacitor 213, wherein the capacitor 213 can be used to smooth the dimming signal S _DM to a constant current level.

控制器220具有一調光輸入端，用於接收調光信號S_DM ；控制器220根據此調光信號S_DM 以產生一切換信號S_W ；控制器220更產生一控制信號S_B ，其中控制信號S_B 根據輸入電壓V_IN 的增加而減少。The controller 220 has a dimming input for receiving the dimming signal S _DM ; the controller 220 generates a switching signal S _W according to the dimming signal S _DM ; the controller 220 further generates a control signal S _B , wherein the control The signal S _B decreases in accordance with an increase in the input voltage V _IN .

經由TRIAC 240，橋式整流器250將此交流電流源V_AC 整流成一直流電流(direct current，DC)輸入電壓V_IN 。負載270包括磁性元件271、整流器272、電容273以及複數個LED 2741~2749。Via the TRIAC 240, the bridge rectifier 250 rectifies the alternating current source V _AC to a direct current (DC) input voltage V _IN . The load 270 includes a magnetic element 271, a rectifier 272, a capacitor 273, and a plurality of LEDs 2741-2749.

功率電晶體260，耦接控制器220以及磁性元件271，以從輸入端T_IN 根據此切換信號S_W 來產生流經LED 2741~2749的一驅動電流I_O 。負載270從此輸入端T_IN 抽取一負載電流I_LD 。LED 2741~2749的調光照明控制是藉由控制驅動電流I_O 的準位的手段來達到。The power transistor 260 is coupled to the controller 220 and the magnetic component 271 to generate a driving current I _O flowing through the LEDs 2741 to 2749 according to the switching signal S _W from the input terminal T _IN . Load 270 draws a load current I _LD from this input terminal T _IN . LED lighting dimming control 2741 - 2749 is controlled by means of the driving current level I _O to achieve.

當可調適泄流器230不存在時，負載電流I_LD 的準位將隨著驅動電流I_O 準位的降低而為相對較低。這將造成TRIAC 240的維持電流不足，因而導致LED 2741~2749燈光的閃爍。此閃爍問題尤其在輸入電壓V_IN 峰谷時將更為嚴重。為了克服此問題，當負載電流I_LD 的準位較低時，控制器220產生控制信號S_B 以控制可調適泄流器230根據此輸入電壓V_IN 抽取泄流電流I_BR 。為了避免燈光的閃爍，泄流電流I_BR 與負載電流I_LD 的總和，其實質上等同於電流I_AC ，必需大於TRIAC 240的最小維持電流。When the adjustable bleeder 230 is not present, the level of the load current I _LD will be relatively low as the drive current I _O level decreases. This will cause the TRIAC 240 to maintain insufficient current, which will cause the LEDs 2741~2749 to flicker. This flicker problem is especially severe when the input voltage V _IN peaks and valleys. To overcome this problem, when the level of the load current I _LD is low, the controller 220 generates a control signal S _B to control the adjustable bleeder 230 to extract the bleeder current I _BR according to the input voltage V _IN . To avoid flashing lights, discharge current I _BR and the sum of the load current I _LD, which is substantially equal to the current I _AC, must be greater than the minimum holding current of the TRIAC 240.

圖3是根據本發明繪示用於LED調光照明電路的控制電路200的控制器220的一實施例。控制器300包括一固定電流源310、切換電路320、偵測電路330、緩衝器340、運算放大器350、電阻360、370與380。固定電流源310產生一固定電流I₃₁₀ ，流向控制器300的調光輸入端。3 is an embodiment of a controller 220 of a control circuit 200 for an LED dimming lighting circuit in accordance with the present invention. The controller 300 includes a fixed current source 310, a switching circuit 320, a detection circuit 330, a buffer 340, an operational amplifier 350, and resistors 360, 370, and 380. The fixed current source 310 generates a fixed current I ₃₁₀ that flows to the dimming input of the controller 300.

切換電路320接收調光信號S_DM ，以產生用於切換繪示於圖2中的功率電晶體260的切換信號S_W 。切換電路320的操作模式對於此領域中普通技術人員是習知技術，於此不再贅述。偵測電路330接收輸入電壓V_IN 以產生一電壓V_INX ，此電壓V_INX 與輸入電壓V_IN 呈比例關係。緩衝器340的正輸入端接收此電壓V_INX ；緩衝器340的負輸入端與輸出端經由電阻360耦接運算放大器350的負輸入端。運算放大器350的正輸入端接收一參考電壓V_REF 。連接介於運算放大器350的負輸入端與輸出端之間的電阻370用於提供一負回授。此外，運算放大器350的輸出端則經由電阻380產生一控制信號S_B 。此控制信號S_B 可以下式表示：The switching circuit 320 receives the dimming signal S _DM to generate a switching signal S _W for switching the power transistor 260 depicted in FIG. The mode of operation of the switching circuit 320 is well known to those of ordinary skill in the art and will not be described herein. Detection circuit 330 receives an input voltage V _IN to generate a voltage V _INX, and this voltage V _INX input voltage V _IN proportional relationship. The positive input of buffer 340 receives this voltage V _INX ; the negative input and output of buffer 340 are coupled via resistor 360 to the negative input of operational amplifier 350. The positive input of operational amplifier 350 receives a reference voltage V _REF . A resistor 370 coupled between the negative input and output of operational amplifier 350 is used to provide a negative feedback. In addition, the output of operational amplifier 350 produces a control signal S _B via resistor 380. This control signal S _B can be expressed by the following formula:

其中，R₃₆₀ 與R₃₇₀ 分別為電阻360與370的電阻值；V₃₈₀ 是電阻380兩端的電壓。由於運算放大器350所提供的負回授，控制信號S_B 將根據電壓V_INX 的增加而減少。其中，電壓V_INX 的偵測與產生的方式已公開於先前技術中，例如美國專利號7,671,578”Detection Circuit for Bleeding the Input Voltage of Transformer”、美國專利號7,656,685”Control Method and Circuit with Indirect Input Voltage Detection by Switching Current Slope Detection”以及美國專利號7,592,790”Start-up Circuit with Feedforward Compensation for Power converters”，因此電壓V_INX 的偵測與產生的描述於此不再贅述。Wherein, R ₃₆₀ and R ₃₇₀ are resistance values of resistors 360 and 370, respectively; and V ₃₈₀ is a voltage across resistor 380. Due to the negative feedback provided by operational amplifier 350, control signal S _B will decrease as voltage V _INX increases. The detection and generation of the voltage V _INX is disclosed in the prior art, for example, U.S. Patent No. 7,671,578 "Detection Circuit for Bleeding the Input Voltage of Transformer", U.S. Patent No. 7,656,685 "Control Method and Circuit with Indirect Input Voltage Detection" By Switching Current Slope Detection" and US Patent No. 7,592,790 "Start-up Circuit with Feedforward Compensation for Power converters", the description of the detection and generation of the voltage V _INX will not be repeated here.

固定電流I₃₁₀ 與分壓器210的等效電阻用於決定調光信號S_DM 的最小準位，其中調光信號S_DM 還用於決定負載電流I_LD 的最小準位。I ₃₁₀ fixed current equivalent resistance voltage divider 210 determines the minimum level of the dimming signal S _DM, wherein the dimming signal S _DM also determines the minimum level of the load current I _LD.

圖4是根據本發明繪示可調適泄流器230的一實施例。可調適泄流器400包括第一電晶體410、第二電晶體430與第三電晶體440、泄流電阻420、電阻460與一齊納二極體(ZENOR diode)450。可調適泄流器400根據控制信號S_B 從輸入端T_IN 抽取一泄流電流I_BR 。於本發明的一實施例中，第二電晶體430是一金屬氧化物半導體場效應電晶體(Metal Oxide Semiconductor Field Effect Transistor，MOSFET)，其為高電壓元件(high voltage device)。第一與第三電晶體410與440是雙載子接面電晶體(Bipolar Junction Transistor，BJT)，其為低電壓元件。4 is an illustration of an embodiment of an adjustable bleeder 230 in accordance with the present invention. The adjustable bleeder 400 includes a first transistor 410, a second transistor 430 and a third transistor 440, a bleeder resistor 420, a resistor 460, and a Zener diode 450. 400 may be adapted to extract a bleeder discharge current I _BR from the input terminal T _IN to the control signal S _B. In an embodiment of the invention, the second transistor 430 is a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), which is a high voltage device. The first and third transistors 410 and 440 are Bipolar Junction Transistors (BJT), which are low voltage components.

第二電晶體430的汲極耦接繪示於圖2的橋式整流器250的輸出端，其即輸入端T_IN 。第二電晶體430的閘極接收一供應電壓V_DD 。於本發明一實施例中，供應電壓V_DD 是控制器220的電源供應電壓。供應電壓V_DD 是藉由磁性元件271的輔助繞阻(未繪示於圖上)所提供。第二電晶體430的源極是連接至第一電晶體410的集極。也就是說，第二電晶體430與第一電晶體410串接以箝制第一電晶體410的最大操作電壓，如第一電晶體410的集極端的電壓。The drain of the second transistor 430 is coupled to the output of the bridge rectifier 250 of FIG. 2, which is the input terminal T _IN . The gate of the second transistor 430 receives a supply voltage V _DD . In an embodiment of the invention, the supply voltage V _DD is the power supply voltage of the controller 220. The supply voltage V _DD is provided by an auxiliary winding of the magnetic element 271 (not shown). The source of the second transistor 430 is a collector connected to the first transistor 410. That is, the second transistor 430 is connected in series with the first transistor 410 to clamp the maximum operating voltage of the first transistor 410, such as the voltage at the collector terminal of the first transistor 410.

泄流電阻420連接於第一電晶體410的射極與參考接地之間。第三電晶體440的基極與集極相連接。而控制信號S_B 則供應至第一電晶體410的基極與第三電晶體440的集極，也就是說，第一電晶體410接收此控制信號S_B 並受其驅動，使得第一電晶體410聯同泄流電阻420根據此控制信號S_B 從輸入端T_IN 抽取一泄流電流I_BR 。The bleeder resistor 420 is coupled between the emitter of the first transistor 410 and the reference ground. The base of the third transistor 440 is connected to the collector. The control signal S _B is supplied to the base of the first transistor 410 and the collector of the third transistor 440, that is, the first transistor 410 receives and is driven by the control signal S _B such that the first crystal 410 with a bleed resistor 420 in accordance with the control signal S _B a discharge current I _BR extracted from the input terminal T _IN.

齊納二極體450的陰極是連接至第三電晶體440的射極，齊納二極體450的陽極是連接至參考接地；其中齊納二極體450耦接第一電晶體410以限制泄流電流I_BR 的最大準位I_BR(MAX) 。The cathode of the Zener diode 450 is connected to the emitter of the third transistor 440, and the anode of the Zener diode 450 is connected to the reference ground; wherein the Zener diode 450 is coupled to the first transistor 410 to limit The maximum level I _{BR(MAX) of the} bleeder current I _BR .

電阻460連接介於第一電晶體410的基極與參考接地之間。電阻460是當控制信號S_B 處於浮動狀態時，用於截止第一電晶體410。第三電晶體440與齊納二極體450介於第一電晶體410的基極與參考接地之間以串聯方式相連接，以提供用於第一電晶體410的最大箝制電壓。其中，可選擇具有相同溫度係數特性的第一與第三電晶體410與440，如此第一電晶體410的基極-射極電壓V_BE 可被第三電晶體440的基極-射極電壓V_BE 所補償。如此一來，橫跨泄流電阻420的電壓將僅藉由齊納二極體450的電壓V_Z1 來決定。因此，在第一電晶體410的集極端的第一電晶體410的最大操作電壓是受第三電晶體430箝制於供應電壓V_DD 之下。泄流電流I_BR 的最大準位I_BR(MAX) 可以下式表示：A resistor 460 is coupled between the base of the first transistor 410 and the reference ground. The resistor 460 is used to turn off the first transistor 410 when the control signal S _{B is} in a floating state. The third transistor 440 and the Zener diode 450 are connected in series between the base of the first transistor 410 and the reference ground to provide a maximum clamping voltage for the first transistor 410. Wherein, the first and third transistors 410 and 440 having the same temperature coefficient characteristic may be selected, such that the base-emitter voltage V _{BE of the} first transistor 410 may be the base-emitter voltage of the third transistor 440 V _BE compensated. As such, the voltage across the bleeder resistor 420 will be determined only by the voltage V _{Z1 of the} Zener diode 450. Therefore, the maximum operating voltage of the first transistor 410 at the collector terminal of the first transistor 410 is clamped under the supply voltage V _DD by the third transistor 430. The maximum level I _{BR(MAX) of the} bleeder current I _BR can be expressed as:

其中V_Z1 是齊納二極體450的電壓，R₄₂₀ 是泄流電阻420的電阻值。Where V _Z1 is the voltage of the Zener diode 450 and R ₄₂₀ is the resistance value of the bleeder resistor 420.

泄流電流I_BR 是根據輸入電壓V_IN 的增加而減少。由於泄流電流I_BR 與第三電晶體430的導通電阻將導致功率損耗，如此來自輸入端T_IN 的泄流電流I_BR 必需根據輸入電壓V_IN 的增加而減少，以減少功率損耗並避免第三電晶體430的過熱。The bleeder current I _BR is reduced in accordance with an increase in the input voltage V _IN . Since the discharge current I _BR and the on-resistance of the third transistor 430 will cause power loss, the drain current I _BR from the input terminal T _IN must be reduced according to the increase of the input voltage V _IN to reduce the power loss and avoid the first The super transistor 430 is overheated.

圖5是根據本發明繪示可調通泄流器230的另一實施例。可調通泄流器500包括第一電晶體510與第二電晶體530、泄流電阻520、電阻560、齊納二極體550與一二極體540，其中第一與第二電晶體510與530、泄流電阻520、電阻560與齊納二極體550的操作方式等同於圖4中的第一、第二電晶體410與430、泄流電阻420、電阻460與齊納二極體450，因此上述元件的描述於此不再贅述。FIG. 5 illustrates another embodiment of an adjustable flow bleeder 230 in accordance with the present invention. The adjustable drain bleeder 500 includes a first transistor 510 and a second transistor 530, a bleeder resistor 520, a resistor 560, a Zener diode 550 and a diode 540, wherein the first and second transistors 510 The operation mode of the 530, the bleeder resistor 520, the resistor 560 and the Zener diode 550 is equivalent to the first and second transistors 410 and 430, the bleeder resistor 420, the resistor 460 and the Zener diode in FIG. 450, therefore, the description of the above elements will not be repeated here.

二極體540，取代繪示於圖4中的第三電晶體440，是用於節省成本；其中二極體540的陽極端是連接至第一電晶體510的基極，二極體540的陰極端是連接至齊納二極體550的陰極。The diode 540, instead of the third transistor 440 shown in FIG. 4, is for cost saving; wherein the anode end of the diode 540 is connected to the base of the first transistor 510, the diode 540 The cathode end is a cathode connected to the Zener diode 550.

圖6是根據本發明繪示可調適泄流器230的又一實施例。可調適泄流器600包括第一電晶體610、第二電晶體630、第三電晶體640、泄流電阻620、電阻660與670、操作電阻690、第一齊納二極體650與第二齊納二極體680；其中第一、第二與第三電晶體610、630與640、泄流電阻620、電阻660以及第一齊納二極體650的操作方式等同於繪示於圖4中的第一、第二與第三電晶體410、430與440、泄流電阻420、電阻460與齊納二極體450，因此上述元件的描述於此不再贅述。FIG. 6 illustrates yet another embodiment of an adjustable bleeder 230 in accordance with the present invention. The adjustable bleeder 600 includes a first transistor 610, a second transistor 630, a third transistor 640, a bleeder resistor 620, resistors 660 and 670, an operating resistor 690, a first Zener diode 650, and a second The Zener diode 680; wherein the first, second and third transistors 610, 630 and 640, the bleeder resistor 620, the resistor 660 and the first Zener diode 650 operate in the same manner as shown in FIG. The first, second and third transistors 410, 430 and 440, the bleeder resistor 420, the resistor 460 and the Zener diode 450 are in the above description, and thus the description of the above elements will not be repeated here.

可調適泄流器600不使用供應電壓V_DD 抽取泄流電流I_BR 。電阻670連接介於第二電晶體630的閘極與汲極之間。第二齊納二極體680連接於第二電晶體630的閘極與參考接地之間。電阻670與第二齊納二極體680用於箝制第一電晶體610的最大操作電壓。600 can be adapted without the use of bleeder supply voltage V _DD drawn bleeder current I _BR. A resistor 670 is coupled between the gate and the drain of the second transistor 630. The second Zener diode 680 is connected between the gate of the second transistor 630 and the reference ground. The resistor 670 and the second Zener diode 680 are used to clamp the maximum operating voltage of the first transistor 610.

此外，操作電阻690是從第一與第二電晶體610與630的接點部分連接至參考接地，以當第一電晶體610受控制信號S_B 控制完全截止時，決定泄流電流I_BR 的最小準位I_BR(MIN) 。泄流電流I_BR 的最小準位I_BR(MIN) 是藉由第二齊納二極體680的電壓V_Z2 與操作電阻690的電阻值所決定，其可以下式表示：Further, the operating resistor 690 is connected from the contact portion of the first and second transistors 610 and 630 to the reference ground to determine the drain current I _BR when the first transistor 610 is completely turned off by the control signal S _B . Minimum level I _BR(MIN) . The minimum level I _BR(MIN) of the bleeder current I _BR is determined by the voltage V _{Z2 of the} second Zener diode 680 and the resistance value of the operating resistor 690, which can be expressed by:

其中V_Z2 是第二齊納二極體680的崩潰電壓，V_TH 是電晶體630的閥值電壓，R₆₉₀ 是操作電阻690的電阻值。Where V _Z2 is the breakdown voltage of the second Zener diode 680, V _TH is the threshold voltage of the transistor 630, and R ₆₉₀ is the resistance value of the operation resistor 690.

圖7是根據分別繪示於圖4與圖5可調適泄流器400與500的實施例中輸入電壓V_IN 、泄流電流I_BR 與負載電流I_LD 的波形圖。由於可調適泄流器400與500並未包括繪示於圖6中的操作電阻690，其泄流電流I_BR 的最小準位I_BR(MIN) 為0。7 is a waveform diagram of input voltage V _IN , bleeder current I _{BR ,} and load current I _LD in accordance with an embodiment of adjustable bleeders 400 and 500 of FIGS. 4 and 5, respectively. Since 400 and 500 adapted bleeder resistor 690 does not include an operation shown in FIG. 6, the discharge current I _BR minimum level I _{BR (MIN)} is zero.

圖8是根據繪示於圖6可調適泄流器600的實施例中輸入電壓V_IN 、泄流電流I_BR 與負載電流I_LD 的波形圖。由於操作電阻690是在第一電晶體610被控制信號S_B 完全截止時，用以決定泄流電流I_BR 的最小準位I_BR(MIN) ，其中泄流電流I_BR 的最小準位I_BR(MIN) 大於0。8 is a waveform diagram of input voltage V _IN , bleeder current I _{BR ,} and load current I _LD in accordance with an embodiment of the adaptive bleeder 600 illustrated in FIG. Since the operation of the first resistor 690 is a transistor 610 when a control signal S _B is completely turned off, discharge current I _BR for determining the minimum level I _{BR (MIN),} wherein the minimum level of the discharge current I _BR I _{BR (MIN) is} greater than 0.

圖9繪示用於LED調光照明電路的控制方法的流程圖。請同時參照圖2~6。於步驟S910中，藉由分壓器(210)根據來自輸入端(T_IN )的輸入電壓(V_IN )以產生調光信號(S_DM )。9 is a flow chart showing a control method for an LED dimming lighting circuit. Please also refer to Figure 2~6. In step S910, the dimming signal (S _DM ) is generated by the voltage divider (210) according to the input voltage (V _IN ) from the input terminal (T _IN ).

於步驟S920中，藉由控制器(220)分別根據調光信號(S_DM )與輸入電壓(V_IN )以分別產生切換信號(S_W )與控制信號(S_B )。於一實施例中，控制信號(S_B )將根據輸入電壓(V_IN )的增加而減少。調光信號(S_DM )的最小準位可藉由耦接分壓器(210)的固定電流源(310)來決定。In step S920, the controller (220) generates a switching signal (S _W ) and a control signal (S _B ) according to the dimming signal (S _DM ) and the input voltage (V _IN ), respectively. In an embodiment, the control signal (S _B ) will decrease as the input voltage (V _IN ) increases. The minimum level of the dimming signal (S _DM ) can be determined by a fixed current source (310) coupled to the voltage divider (210).

於步驟S930中，藉由可調適泄流器(230)根據控制信號(S_B )以從輸入端(T_IN )抽取出泄流電流(I_BR )，其中泄流電源(I_BR )的最大準位(I_BR(MAX) )可藉由耦接電晶體(410)的第一齊納二極體(450)所限制。泄流電流(I_BR )的最小準位(I_BR(MIN) )可藉由耦接第一電晶體(610)與第二電晶體(630)的操作電阻(690)所限制。In step S930, may be adapted by the bleeder (230) in accordance with a control signal (S _B) to extract from the input terminal (T _IN) the discharge current (I _BR), wherein the maximum discharge power (I _BR) of The level (I _BR(MAX) ) can be limited by the first Zener diode (450) coupled to the transistor (410). The minimum level of the bleeder current ( _IBR ) ( _IBR(MIN) ) can be limited by the coupling of the operating resistance (690) of the first transistor (610) and the second transistor (630).

於步驟S940中，藉由第二電晶體(430)箝制第一電晶體(410)的最大操作電壓。用於第一電晶體(410)的此最大操作電壓可藉由耦接第二電晶體(630)的第二齊納二極體(680)所限制。In step S940, the maximum operating voltage of the first transistor (410) is clamped by the second transistor (430). This maximum operating voltage for the first transistor (410) can be limited by a second Zener diode (680) coupled to the second transistor (630).

於本發明中，提供一種用於LED調光照明電路的控制電路與控制方法。根據本發明，泄流電流I_BR 與負載電流I_LD 的總和大於TRIAC的最小維持電流，如此可避免LED燈光的閃爍。本發明的目的之一在於提供具有可調適泄流器的控制電路，此可調適泄流器是用於LED調光照明電路而不造成燈光閃爍。本發明的另一目的在於提供具有低功耗的高效率LED照明電路。In the present invention, a control circuit and a control method for an LED dimming lighting circuit are provided. According to the present invention, the sum of the bleeder current _IBR and the load current _ILD is greater than the minimum TRIAC holding current, so that flickering of the LED light can be avoided. One of the objects of the present invention is to provide a control circuit with an adjustable bleeder for use in an LED dimming lighting circuit without causing flashing of the light. Another object of the present invention is to provide a high efficiency LED lighting circuit with low power consumption.

綜上所述，雖然本發明已以較佳實施例公開如上，然其並非用以限定本發明。本發明所屬技術領域中的普通技術人員，在不脫離本發明的精神和範圍內，當可作各種更動與潤飾。因此，本發明的保護範圍當以後附的權利要求書的保護範圍為準。In the above, although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the invention. Various modifications and refinements can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

100．．．調光照明電路100. . . Dimming lighting circuit

110．．．雙向閘流體(TRIAC)110. . . Two-way thyristor (TRIAC)

120．．．橋式整流器120. . . Bridge rectifier

130．．．負載130. . . load

200．．．用於LED調光照明電路的控制電路200. . . Control circuit for LED dimming lighting circuit

210．．．分壓器210. . . Voltage divider

211、212．．．電阻211, 212. . . resistance

213．．．電容213. . . capacitance

220．．．控制器220. . . Controller

230．．．可調適泄流器230. . . Adjustable drain

240．．．雙向閘流體240. . . Two-way thyristor

250．．．橋式整流器250. . . Bridge rectifier

260．．．功率電晶體260. . . Power transistor

270．．．負載270. . . load

271．．．磁性元件271. . . Magnetic component

272．．．整流器272. . . Rectifier

273．．．電容273. . . capacitance

2741~2749．．．發光二極體(LED)2741~2749. . . Light-emitting diode (LED)

300．．．控制器300. . . Controller

310．．．固定電流源310. . . Fixed current source

320．．．切換電路320. . . Switching circuit

330．．．偵測電路330. . . Detection circuit

340．．．緩衝器340. . . buffer

350．．．運算放大器350. . . Operational Amplifier

360、370、380．．．電阻360, 370, 380. . . resistance

400、500、600．．．可調通泄流器400, 500, 600. . . Adjustable flow bleeder

410、510、610．．．第一電晶體410, 510, 610. . . First transistor

420、520、620．．．泄流電阻420, 520, 620. . . Discharge resistor

430、530、630．．．第二電晶體430, 530, 630. . . Second transistor

440、640．．．第三電晶體440, 640. . . Third transistor

450、550．．．齊納二極體450, 550. . . Zener diode

460、560、660、670．．．電阻460, 560, 660, 670. . . resistance

540．．．二極體540. . . Dipole

650．．．第一齊納二極體650. . . First Zener diode

680．．．第二齊納二極體680. . . Second Zener diode

690．．．操作電阻690. . . Operating resistance

I₃₁₀ ．．．固定電流I ₃₁₀ . . . Fixed current

I_AC ．．．電流I _AC . . . Current

I_BR ．．．泄流電流I _BR . . . Discharge current

I_BR(MAX) ．．．泄流電流I_BR 的最大準位I _BR(MAX) . . . Maximum level of discharge current I _BR

I_BR(MIN) ．．．泄流電流I_BR 的最小準位I _BR(MIN) . . . Minimum level of discharge current I _BR

I_LD ．．．負載電流I _LD . . . Load current

I_O ．．．驅動電流I _O . . . Drive current

S910~S940．．．流程步驟S910~S940. . . Process step

S_B ．．．控制信號S _B . . . control signal

S_DM ．．．調光信號S _DM . . . Dimming signal

S_W ．．．切換信號S _W . . . Switching signal

T_IN ．．．輸入端T _IN . . . Input

V_AC ．．．交流電流源V _AC . . . AC current source

V_DD ．．．供應電壓V _DD . . . Supply voltage

V_IN ．．．輸入電壓V _IN . . . Input voltage

V_INX ．．．電壓V _INX . . . Voltage

V_REF ．．．參考電壓V _REF . . . Reference voltage

圖1繪示傳統調光照明電路的電路圖。FIG. 1 is a circuit diagram of a conventional dimming lighting circuit.

圖2繪示根據本發明用於LED調光照明電路的一實施例。2 illustrates an embodiment of an LED dimming lighting circuit in accordance with the present invention.

圖3繪示根據本發明用於LED調光照明電路的控制電路的控制器的一實施例。3 illustrates an embodiment of a controller for a control circuit for an LED dimming lighting circuit in accordance with the present invention.

圖4繪示根據本發明可調適泄流器的一實施例。4 illustrates an embodiment of an adjustable bleeder in accordance with the present invention.

圖5繪示根據本發明可調適泄流器的另一實施例。Figure 5 illustrates another embodiment of an adjustable bleeder in accordance with the present invention.

圖6繪示根據本發明可調適泄流器的又一實施例。Figure 6 illustrates yet another embodiment of an adjustable bleeder in accordance with the present invention.

圖7分別繪示根據於圖4與圖5中可調適泄流器的實施例，繪示輸入電壓V_IN 、泄流電流I_BR 與負載電流I_LD 的波形圖。7 is a waveform diagram showing an input voltage V _IN , a bleed current I _{BR ,} and a load current I _LD according to an embodiment of the adjustable bleeder of FIGS. 4 and 5 , respectively.

圖8繪示根據於圖6中可調適泄流器的實施例，繪示輸入電壓V_IN 、泄流電流I_BR 與負載電流I_LD 的波形圖。8 is a waveform diagram showing an input voltage V _IN , a bleeder current I _{BR ,} and a load current I _LD according to an embodiment of the adaptive bleeder of FIG. 6 .

圖9繪示用於LED調光照明電路的控制方法的流程圖。9 is a flow chart showing a control method for an LED dimming lighting circuit.

210．．．分壓器210. . . Voltage divider

211、212．．．電阻211, 212. . . resistance

213．．．電容213. . . capacitance

220．．．控制器220. . . Controller

230．．．可調通泄流器230. . . Adjustable flow bleeder

240．．．雙向閘流體240. . . Two-way thyristor

250．．．橋式整流器250. . . Bridge rectifier

260．．．功率電晶體260. . . Power transistor

270．．．負載270. . . load

271．．．磁性元件271. . . Magnetic component

272．．．整流器272. . . Rectifier

273．．．電容273. . . capacitance

2741~2749．．．發光二極體(LED)2741~2749. . . Light-emitting diode (LED)

I_BR ．．．泄流電流I _BR . . . Discharge current

I_LD ．．．負載電流I _LD . . . Load current

I_O ．．．驅動電流I _O . . . Drive current

S_B ．．．控制信號S _B . . . control signal

S_DM ．．．調光信號S _DM . . . Dimming signal

S_W ．．．切換信號S _W . . . Switching signal

T_IN ．．．輸入端T _IN . . . Input

V_AC ．．．交流電流源V _AC . . . AC current source

V_DD ．．．供應電壓V _DD . . . Supply voltage

V_IN ．．．輸入電壓V _IN . . . Input voltage

Claims

一種調光發光二極體(Light Emitting Diode，LED)照明電路的控制電路，包括：一分壓器，接收來自一輸入端的一輸入電壓以產生一調光信號；一控制器，根據該調光信號以產生一切換信號，其中該控制器還根據該輸入電壓產生一控制信號；以及一可調適泄流器，接收該控制信號並根據該控制信號從該輸入端抽取一泄流電流；其中，該控制器包括一固定電流源，耦接該分壓器以決定該調光信號的一最小準位。 A control circuit for a Light Emitting Diode (LED) lighting circuit includes: a voltage divider that receives an input voltage from an input to generate a dimming signal; and a controller that adjusts the light according to the dimming a signal to generate a switching signal, wherein the controller further generates a control signal according to the input voltage; and an adjustable bleeder, receiving the control signal and extracting a bleed current from the input terminal according to the control signal; wherein The controller includes a fixed current source coupled to the voltage divider to determine a minimum level of the dimming signal.

根據申請專利範圍1所述之控制電路，其中該控制信號根據該輸入電壓的增加而減少。 The control circuit of claim 1, wherein the control signal is reduced in accordance with an increase in the input voltage.

根據申請專利範圍1所述之控制電路，其中該可調適泄流器包括：一第一電晶體，接收該控制信號；一泄流電阻，耦接該第一電晶體，其中該第一電晶體聯同該泄流電阻根據該控制信號以從該輸入端抽取該泄流電流；以及一第二電晶體，串接該第一電晶體以箝制該第一電晶體的一最大操作電壓。 The control circuit of claim 1, wherein the adjustable bleeder comprises: a first transistor receiving the control signal; a bleeder resistor coupled to the first transistor, wherein the first transistor And the bleeder resistor is configured to extract the bleed current from the input terminal according to the control signal; and a second transistor serially connecting the first transistor to clamp the first transistor A maximum operating voltage.

根據申請專利範圍3所述之控制電路，更包括一第一齊納二極體，耦接該第一電晶體以限制該泄流電流的一最大準位，其中該第一電晶體為一低電壓元件(low-voltage device)。 The control circuit of claim 3, further comprising a first Zener diode coupled to the first transistor to limit a maximum level of the bleed current, wherein the first transistor is a low Low-voltage device.

根據申請專利範圍4所述之控制電路，還包括一第二齊納二極體，耦接該第二電晶體以限制用於該第一電晶體的一最大操作電壓，其中該第二電晶體為一高電壓元件(high-voltage device)。 The control circuit of claim 4, further comprising a second Zener diode coupled to the second transistor to limit a maximum operating voltage for the first transistor, wherein the second transistor It is a high-voltage device.

根據申請專利範圍3所述之控制電路，還包括一操作電阻，耦接該第一電晶體與該第二電晶體以決定該泄流電流的一最小準位。 The control circuit of claim 3, further comprising an operating resistor coupled to the first transistor and the second transistor to determine a minimum level of the bleed current.

根據申請專利範圍1所述之控制電路，其中該可調適泄流器包括：一第一電晶體，接收該控制信號；一泄流電阻，耦接該第一電晶體，其中該第一電晶體聯同該泄流電阻以根據該控制信號從該輸入端抽取該泄流電流；以及一第二電晶體，串接該第一電晶體以箝制該第一電晶體的一最大操作電壓。 The control circuit of claim 1, wherein the adjustable bleeder comprises: a first transistor receiving the control signal; a bleeder resistor coupled to the first transistor, wherein the first transistor The bleeder resistor is coupled to extract the bleed current from the input terminal according to the control signal; and a second transistor is coupled to the first transistor to clamp a maximum operating voltage of the first transistor.

根據申請專利範圍1所述之控制電路，還包括一功率電晶體，耦接該控制器，用於根據該切換信號從該輸入端產生用於調光發光二極體(LEDs)的一驅動電流。 The control circuit of claim 1 further includes a power transistor coupled to the controller for generating a driving current for the dimming light emitting diodes (LEDs) from the input terminal according to the switching signal. .

根據申請專利範圍7所述之控制電路，還包括：一第一齊納二極體，耦接該第一電晶體以限制該泄流電流的一最大準位；以及一第二齊納二極體，耦接該第二電晶體以限制用於該第一電晶體的該最大操作電壓。 The control circuit of claim 7, further comprising: a first Zener diode coupled to the first transistor to limit a maximum level of the bleed current; and a second Zener diode The second transistor is coupled to limit the maximum operating voltage for the first transistor.

根據申請專利範圍9所述之控制電路，更包括一操作電阻，耦接該第一電晶體與該第二電晶體以限制該泄流電流的一最小準位。 The control circuit of claim 9 further includes an operating resistor coupled to the first transistor and the second transistor to limit a minimum level of the bleed current.

一種調光發光二極體(Light Emitting Diode，LED)照明電路的控制方法，包括：藉由一分壓器根據來自一輸入端的一輸入電壓以產生一調光信號；藉由一控制器分別根據該調光信號與該輸入電壓以分別產生一切換信號與一控制信號；以及藉由一可調適泄流器根據該控制信號以從該輸入端抽取一泄流電流；其中，藉由耦接該分壓器的一固定電流源來決定該調光信號的一最小準位。 A method for controlling a lighting circuit of a Light Emitting Diode (LED), comprising: generating a dimming signal according to an input voltage from an input terminal by a voltage divider; The dimming signal and the input voltage respectively generate a switching signal and a control signal; and an adjustable current bleeder extracts a bleed current from the input terminal according to the control signal; wherein, by coupling A fixed current source of the voltage divider determines a minimum level of the dimming signal.

根據申請專利範圍11所述之控制方法，其中該控制信號根據該輸入電壓的增加而減少。 The control method according to claim 11, wherein the control signal is decreased in accordance with an increase in the input voltage.

根據申請專利範圍11所述之控制方法，其中該可調適泄流器包括：一第一電晶體，接收該控制信號；一泄流電阻，耦接該第一電晶體，其中該第一電晶體聯同該泄流電阻根據該控制信號從該輸入端抽取該泄流電流；以及一第二電晶體，串接該第一電晶體以箝制該第一電晶體的一最大操作電壓。 The control method of claim 11, wherein the adjustable bleeder comprises: a first transistor receiving the control signal; a bleeder resistor coupled to the first transistor, wherein the first transistor The bleeder resistor is coupled to the bleeder current from the input terminal according to the control signal; and a second transistor is coupled to the first transistor to clamp a maximum operating voltage of the first transistor.

根據申請專利範圍13所述之控制方法，還包括：藉由一第二電晶體箝制該第一電晶體的一最大操作電壓。 The control method of claim 13, further comprising: clamping a maximum operating voltage of the first transistor by a second transistor.

根據申請專利範圍13所述之控制方法，還包括藉由一第一齊納二極體耦接該第一電晶體，來限制該泄流電流的一最大準位。 The control method of claim 13 further includes limiting a maximum level of the bleed current by coupling the first Zener diode to the first transistor.

根據申請專利範圍13所述之控制方法，還包括藉由一第二齊納二極體耦接該第二電晶體，來限制該第一電晶體的該最大操作電壓。 The control method of claim 13, further comprising limiting the maximum operating voltage of the first transistor by coupling the second transistor to the second transistor.

根據申請專利範圍13所述之控制方法，還包括藉由一操作電阻耦接該第一電晶體與該第二電晶體，來限制該泄流電流的一最小準位。 According to the control method of claim 13, the method further includes The first transistor and the second transistor are coupled to each other to limit a minimum level of the bleed current.