201143514 六、發明說明： 【發明所屬之技術領域】 本發明係關於一種發光二極體驅動電路及背光模組，尤指 一種根據顯示器之一維度切換訊號進行模式切換之發光二極 體驅動電路及背光模組。 【先則技術】 與傳統的光源相比，發光二極體（led)具備許多優點， 包括工作電壓低、效能高、壽命長、色彩豐富、產生定向光以 及不含汞等，能夠提供極寬廣的色彩以及白光，避免紅外線(IR) 或紫外線(UV)輻射的產生。LED作為光源時為人詬病的高成 本及散熱問正快速得到改善’以發光二極體取代現今的照明 光源已成為趨勢。因此，在大尺寸LCD顯示器中，用LED背 光的比重也不斷攀升，帶動LED產業大幅成長。 LCD顯示器現今的趨勢為3D顯示，尤其在近年來3d電 影的推波助瀾之下’ 3D顯示的LCD顯示器已逐漸被使用者所 接/受。但，也由於現今的使用需求仍以2D為主，LCD顯示器 必須具有顯示2D及3D的能力。然而，LCD顯示器在2D顯 示與3D顯示時需要對應不同的亮度顯示，而目前的LED ^ ^控制f軸大部分具有調光魏，但是並無法滿足這樣的需 ，，也就疋在維持2D顯示的調光的同時，也能對應2D/3D切 換而於3D顯示時提供不同的亮度。 【發明内容】 ,·鑑於先前技術中的led驅動控制器並無法隨著顯示器進 行2D/3D切換時’提供不同的亮度，本發明利用發光二極體 ^動電路來提供發光二極體模組的電流平衡魏的同時，也同 ^根據維度切換訊號來提供不同的電流流經發光二極體模 以1 到對應不同的顯示模式供發光二才亟體模組可提供不同 的顯示亮度’時’也可以透過控儀根據訊號來達到 201143514 調光之作用。 為達上述目的，本發明提供了一種發光二極體驅動電路， 包含一發光二極體模組及一電流控制元件^發光二極體模組具 有複數個發光二極體串，每一複數個發光二極體串具有一驅動 %。電流控制元件具有複數個電流平衡端，對應柄接至呰驅動 端，以平衡每一複數個發光二極體串流經之電^大小。其中， 電流控制元件根據一模式切換訊號，於模式切換訊號代表一第 一模式時’平衡每一複數個發光二極體串流經之電流於一第一 電々IL值，於模式切換訊號代表一第二模式時，平衡每一複數個 發光二極體串流經之電流於一第二電流值。 本發明也&供了 一種背光模組，包含一發光二極體模組、 :轉換電路、一電流控制元件以及一控制器。轉換電路耦接一 輸入電源，以根據一控制訊號將輸入電源之電力轉換成一輸出 電壓以驅動發光二極體模組。電流控制元件耦接發光二極體模 組，以平衡流經發光二極體模組中發光二極體之電流大小。控 制器接收代表輸出電壓之一電壓迴授訊號以穩定輸出電壓之 ，壓值’絲據-調光纖_整發光二極麵組之亮度。其 制元件根據一模式切換訊號，於模式切換訊號代^ 第一模式時，控制流經發光二極體模組之電流大小於一第一 於模式切換訊號代表—第二模式時，控制流經發光二 極體模組之電流大小於一第二電流值。 以上的概述與接下來的詳細說明皆為示範性質， 優點說=^^的中請專利範圍。而有關本發明的其他目的與 優點，將在後續的說明與圖示加以闡述。 、 【實施方式】 闯^見第一圖，為根據本發明之發光二極體驅動電路示素 1發光—極體驅動電路包含了 —發光二極體模組如二 電流控制讀60。發光三極麵組5G具錢_發光二^ 201143514 串複數個發光二極體串之一端彼此搞接至一驅動電壓vddh 以接收電力’而每-複數個發光二極體串具有—驅動端。電流 控制疋件60具有複數個電流控制單元65，複數個電流控制單 兀65各自具有對應的電流平衡端卯〜此，對應耦接至發光二 極體模組50中複數個發光二極體串的複數個驅動端，以使複 ，個發光二極體串流經約略相同之驅動電流。在本實施例中， 每一複^個電流控制單元65包含一第一電晶體開關61、一誤 差放大器62以及一電阻調變單位66，其中電阻調變單位66 包含二第二電晶體開關63、一第一偵測單元以及一第二 偵測單元Rr2。第一電晶體開關61的一第一端作為電流平衡 端’ 一第二端透過第一偵測單元耦接地並產生一電流偵測 訊號IFB，其中電流偵測訊號IFB的準位高低代表流經對應之 電流平衡端之電流大小，即，對應之發光二極體串之電流大 小。第二電晶體開關63的一第一端與第一電晶體開關61的第 亏端耦接，其第二端透過第二偵測單元办2耦接地。誤差放大 器62於非反向輸入端接收一參考電壓訊號Vr，於反向輸入端 接收電流偵測訊號IFB，於輸出端耦接第一電晶體開關61的 一控制端’並據此達到回授補償之作用而控制第一電晶體開關 61之導通情況’使參考電壓訊號Vr等於電流偵測訊號ifb之 準位’即，使對應發光二極體串之電流大小穩定於一電流值。 第二電晶體開關63根據一模式切換訊號ssw控制第一偵測單 元Rrl以及第二偵測單元電性連接與否，在此模式切換訊 號Ssw可以是控制顯示器進行2D模式/3D模式切換的一維度 切換訊號。當模式切換訊號Ssw代表一第一模式，例如：高 準位時，第二電晶體開關63導通，第二偵測單元办2及第一 偵測單元Rrl並聯使其等效電阻值較低，此時第一電晶體開關 61會穩定流過較大的電流使電流偵測訊號IFB之準位等於參 考電壓訊號Vr。當模式切換訊號Ssw代表一第二模式，例如： ，低準位時，第二電晶體開關63截止’偵測電流由第一偵測 早元Rrl產生，此時第一電晶體開關61會流過較小的電流使 201143514 電流偵測訊號IFB之準位仍等於參考電壓訊號Vr。上述之 施例中，每一複數個電流控制單元65均接收相同之參考電壓 訊號Vr，使每一複數個發光二極體串流經之電流幾乎相同。 因此，如上所述，電阻調變單位66的等效阻值會根據模式切 換訊號Ssw所代表的模式進行調變，使電流平衡端 、士 小會隨模式切換訊號Ssw所代表的模式來改變。 机大BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-emitting diode driving circuit and a backlight module, and more particularly to a light-emitting diode driving circuit for switching modes according to a dimension switching signal of a display and Backlight module. [First-class technology] Compared with traditional light sources, LEDs have many advantages, including low operating voltage, high performance, long life, rich colors, directional light, and mercury-free. The color and white light to avoid the generation of infrared (IR) or ultraviolet (UV) radiation. When LEDs are used as light sources, the high cost of heat and heat dissipation are rapidly improving. It has become a trend to replace today's illumination sources with light-emitting diodes. Therefore, in large-size LCD displays, the proportion of LED backlights continues to rise, driving the LED industry to grow substantially. The current trend of LCD displays is 3D display, especially under the influence of 3D movies in recent years. 3D display LCD displays have gradually been accepted and accepted by users. However, because today's usage requirements are still dominated by 2D, LCD displays must have the ability to display 2D and 3D. However, the LCD display needs different brightness display in 2D display and 3D display, and the current LED ^ ^ control f axis mostly has dimming Wei, but can not meet such needs, and thus maintain 2D display. At the same time of dimming, it can also provide different brightness for 3D display in response to 2D/3D switching. SUMMARY OF THE INVENTION The present invention utilizes a light-emitting diode circuit to provide a light-emitting diode module in view of the fact that the LED driver controller of the prior art does not provide different brightness when the display is 2D/3D switched. At the same time, the current balance is also the same as that according to the dimension switching signal to provide different currents flowing through the LED module to correspond to different display modes for the illumination module to provide different display brightness. 'You can also use the controller to achieve the effect of 201143514 dimming according to the signal. In order to achieve the above object, the present invention provides a light emitting diode driving circuit, comprising a light emitting diode module and a current control component, and the light emitting diode module has a plurality of light emitting diode strings, each of which is plural The LED string has a drive %. The current control component has a plurality of current balancing ends, and the corresponding handle is connected to the 呰 driving end to balance the voltage of each of the plurality of LED strings. Wherein, the current control component switches the signal according to a mode, and when the mode switching signal represents a first mode, 'balances the current flowing through each of the plurality of LED strings to a first voltage, and the mode switching signal represents a In the second mode, the current flowing through each of the plurality of LED strings is balanced to a second current value. The present invention also provides a backlight module including a light emitting diode module, a conversion circuit, a current control element, and a controller. The conversion circuit is coupled to an input power source for converting the power of the input power source into an output voltage according to a control signal to drive the LED module. The current control component is coupled to the LED module to balance the current flowing through the LED in the LED module. The controller receives a voltage feedback signal representing one of the output voltages to stabilize the output voltage, and the voltage value is the brightness of the light-emitting diode. The component is switched according to a mode, and when the mode switching signal is in the first mode, the current flowing through the LED module is controlled to be a mode switching signal representative - the second mode, the control flows through The current of the LED module is at a second current value. The above summary and the following detailed description are exemplary, and the advantages are said to be in the range of patents. Other objects and advantages of the present invention will be described in the following description and drawings. [Embodiment] 第一 ^ See the first figure, which is a light-emitting diode driving circuit according to the present invention. The light-emitting body driving circuit includes a light-emitting diode module such as a two-current control read 60. The light-emitting three-pole surface group 5G has money _ light-emitting two ^ 201143514 One of the plurality of light-emitting diode strings is connected to each other to a driving voltage vddh to receive power 'and each of the plurality of light-emitting diode strings has a driving end. The current control unit 60 has a plurality of current control units 65. Each of the plurality of current control units 65 has a corresponding current balance terminal. The plurality of current control units 65 are coupled to the plurality of LED strings in the LED module 50. The plurality of driving ends are such that the plurality of light emitting diodes flow through approximately the same driving current. In this embodiment, each of the plurality of current control units 65 includes a first transistor switch 61, an error amplifier 62, and a resistance modulation unit 66, wherein the resistance modulation unit 66 includes two second transistor switches 63. a first detecting unit and a second detecting unit Rr2. A first end of the first transistor switch 61 serves as a current balancing end. A second end is coupled to the first detecting unit and generates a current detecting signal IFB. The level of the current detecting signal IFB is represented by a current flowing through the current detecting signal IFB. The current level of the corresponding current balance terminal, that is, the current magnitude of the corresponding LED string. A first end of the second transistor switch 63 is coupled to the first end of the first transistor switch 61, and a second end of the second transistor switch 63 is coupled to the second detecting unit. The error amplifier 62 receives a reference voltage signal Vr at the non-inverting input terminal, receives the current detecting signal IFB at the inverting input terminal, and is coupled to a control terminal of the first transistor switch 61 at the output end and is accordingly fed back. The conduction state of the first transistor switch 61 is controlled to make the reference voltage signal Vr equal to the level of the current detecting signal ifb, that is, the current level of the corresponding LED string is stabilized to a current value. The second transistor switch 63 controls the first detecting unit Rrl and the second detecting unit to be electrically connected according to a mode switching signal ssw. The mode switching signal Ssw may be a control panel for performing 2D mode/3D mode switching. Dimension switching signal. When the mode switching signal Ssw represents a first mode, for example, the high level switch, the second transistor switch 63 is turned on, and the second detecting unit 2 and the first detecting unit Rrl are connected in parallel to make the equivalent resistance value lower. At this time, the first transistor switch 61 will stably flow a large current so that the level of the current detecting signal IFB is equal to the reference voltage signal Vr. When the mode switching signal Ssw represents a second mode, for example: when the low level, the second transistor switch 63 is turned off, the detecting current is generated by the first detecting early element Rrl, and the first transistor switch 61 will flow. A small current makes the level of the 201143514 current detection signal IFB still equal to the reference voltage signal Vr. In the above embodiment, each of the plurality of current control units 65 receives the same reference voltage signal Vr, so that the current flowing through each of the plurality of LED strings is almost the same. Therefore, as described above, the equivalent resistance of the resistance modulation unit 66 is modulated according to the mode represented by the mode switching signal Ssw, so that the current balance terminal and the small value change with the mode represented by the mode switching signal Ssw. Large machine
请參見第二圖，為根據本發明之一較佳實施例之電流控制 元件之電路示意圖。電流控制單元165包含一第一電晶體開 161: —第一偵測單元Rrl、一誤差放大器162以及一電流調 變單位166。第一電晶體開關161之一端作為電流平衡端 以耦接對應發光二極體串之驅動端。誤差放大器162接收一 源電壓VDDL，並由電源電壓vdDL提供誤差放大器162運 作所需之電力。值得注意的是，電源電壓VDDL可與電流控 制元件的驅動電壓不同，尤以高於電流控制元件的驅動電^ 佳。如此，誤差放大器162可以提供較高準位的訊號控制第一 電晶體開關161的閘極而達到降低第一電晶體開關161的導通 阻抗之優點。誤差放大器162於非反向輸入端接收一參考電壓 訊號Vr，且於反向輸入端接收一第一偵測單元办丨所產生的 一電流偵測訊號IFB，並據此達到回授補償之作用而控制第一 電晶體開關161之狀態。電流調變單位166包含一第二電曰 開關163、一第二偵測單元Rx2以及一阻抗單元，第二電 ，體開關163的一第一端耦接第一電晶體開關161與第一偵測 單70办1的連接點，其第二端透過第二偵測單元Rr2耦接地， 其控制端透過阻抗單元Rr3接收模式切換訊號Ssw。在本實施 例，，第二電晶體開關為一雙載子電晶體，並根據一模式切換 ，號Ssw控制流經電流平衡端Dx之電流大小。當模式切換訊 號Ssw為低準位時，第二電晶體開關163截止，流經電流^ 衡fDx的電流同時流經第一偵測單元Rrl以產生與參考^壓 訊號Vr相同準位之電流偵測訊號IFB，在此時流經電流平衡 知Dx的電流值為第_電流值。當模式切換訊號為高準位 201143514 平㈣^電Γ體開_163導通而流經一穩定電流，使流經電流 的電流部分經電流調變單位166而部分流經第一债 V在此時赦電辭衡^Dx的電雜為第二電流 抛電f被分流的情況下’電流_訊號1FB仍被控 枯賴峨Vr㈣準位，即第二電流值等於第一電流 杨上流經電流調變單位166之電流。因此，透過電流調變單 f i6 Λ錢’使錢平衡獻紐大小魏默切換訊號 Ssw所代表的模式來改變。 备然，除了上述的實施例中的電流控制元件之電路架構 外丨電流控制元件亦可使用其他具有均流功能之電路架構，例 如·電流鏡，來控制流經每一複數個發光二極體串之電流，使 得每一個電流控制單元之電流平衡端上之電流幾乎相同。 除了如上述實施例利用調整電流偵測訊號以達到切換模 式之目的外，亦可透過參考電壓訊號Vr來達到相同之切換模 式功能，即此時第一圖所示之實施例可省略電阻調變單位66， 而第二圖所示之實施例可省略電流調變單位166。請參見第三 圖，為根據本發明之一較佳實施例之參考電壓產生器之電路示 意圖。參考電壓產生器包含一電流鏡271、一第一電晶體開關 272、一第二電晶體開關263、一誤差放大器273、一第一偵測 早元274以及參考電阻Rl、R2、R3、R4。參考電阻ri、R2 串聯於電源電壓VCC及地之間，參考電阻R3透過第二電晶 體開關263搞接至參考電阻Ri、R2之連接點以產生一分壓訊 號Vb至誤差放大器273於非反向輸入端。第一電晶體開關272 與第一偵測單元274串聯，其連接點產生一電流偵測訊號Va 至誤差放大器273的反向輸入端。藉此’誤差放大器273於輸 出輸出§fl號以控制第一電晶體開關272的等效電阻值，使電 流偵測訊號Va之準位及分壓訊號Vb之準位相等進而使流經 第一偵測單元274的電流穩定。電流鏡271輕接電源電壓 VCC ’ 一端透過第一電晶體開關272耦接第一偵測單元274， 並於另一端透過電流鏡像作用產生與第一電晶體開關272的 201143514 ，流固定關之錢流經參考電阻R4，以產生―參考電 ，Vr。第二電晶體開關263根據一模式切換訊號& ί 之電流_訊號Vb。當模式切親號Ssw 為呵準位時’第一電晶體開關263導通，此時電流摘測訊號 Vb的準位較低。而當模式切換訊號Ssw為低準位時，雷 晶體開關263截止，此時電流偵測訊號％的準位較高。因此， 透過調整電流_訊號Vb的準位即可調整流經參考電阻斛 的電流，進而產生不同準位之參考電壓訊號於第三 示之參考電壓產生H ’其產生的參考龍訊號Vr可以提供至 第一，及第二圖所示之誤差放大器之非反向輸入端。-凊參見第四圖’為根據本發明之一較佳實施例之背光模組 之電路方塊圖。背光模組包含一轉換電路34〇、一發光二極體 模^ 、一電流控制元件360、一控制器c〇N以及一電壓箝 制單70 380。轉換電路340耦接一輸入電源Vin ,以根據一控 制訊號將該輸入電源Vin之電力轉換成一輸出電壓v〇ut以^ 動發光二極體模組350。控制器C0N接收代表輸出電壓v〇ut 之電壓回授訊號FB以穩定該輸出電壓v〇ut之電壓值，並根 據一調光訊號DIM以調整該發光二極體模組35〇之亮度。電 流控制元件360透過至少一電流平衡端Dx對應辆接發光二極 體模組350中的發光二極體串，以穩定流經發光二極體模組 po之電流大小。此外，電流控制元件36〇根據一模式切換訊 號Ssw ’於該模式切換訊號Ssw代表一第一模式時，控制流經 發光二極體模組350之電流大小於一第一電流值，於模式切換 訊號Ssw代表一第二模式時，控制流經發光二極體模組35〇 之電流大小於一第二電流值。電壓箝制單元38〇耦接發光二極 體模組350之電流平衡端Dx，可使電流平衡端〇χ之電壓， 即電流控制元件360的跨壓，箝制於一電壓值之内。在本實施 例中，電壓箝制單元380可以包含至少一電阻，分別對應耦接 至少一電流平衡端Dx ’使在調光訊號DIM代表off時，發 光二極體模組350中對應的發光二極體串之電壓落在發光的 201143514 之驅動端Dx ^附近，藉此以防止發光二極體模組35〇 ί麟讀為關本發明之制。餘意的是，軌與該實施例 發明完全符合專利三要件：新穎性、進性 2 if ίίί應理解的是’該實施例翻於描繪本發明： 【圖式簡單說明】 第-圖為根據本發明之—發光二極體驅動電路示意圖。 第二圖為根據本發明之-電流控制元件t路示意圖。 第三圖為根據本發明之—參考電壓產生器電路示意圖。 第四圖為根據本發明之—背光模組之電路方塊圖。 【主要元件符號說明】 本發明： 轉換電路 340 發光二極體模組 50 > 350 電流控制元件 60 > 360 第一電晶體開關 61、161、272 誤差放大器 62、162、273 第一電晶體開關 63、163、263 電流控制單元 65、165 電流調變單位 66 ' 166 電流鏡 271 第一偵測單元 Rrl、274 第二偵測單元 Rr2 201143514 參考電阻 R1 > R2 ' R3 ' R4 阻抗單元 Rr3 電壓箝制單元 380 控制器 CON 電流偵測訊號 Va 分壓訊號 Vb 模式切換訊號 Ssw 驅動電壓 VDDH 電源電壓 VDDL > VCC 輸入電源 Yin 輸出電源 電壓回授訊號 電流偵測訊號 調光訊號 電流平衡端 參考電壓訊號Referring to the second figure, there is shown a circuit diagram of a current control element in accordance with a preferred embodiment of the present invention. The current control unit 165 includes a first transistor 161: a first detecting unit Rrl, an error amplifier 162, and a current modulation unit 166. One end of the first transistor switch 161 serves as a current balancing end to couple the driving end of the corresponding LED string. Error amplifier 162 receives a source voltage VDDL and provides the power required by error amplifier 162 from supply voltage vdDL. It is worth noting that the power supply voltage VDDL can be different from the driving voltage of the current control element, especially higher than the driving power of the current control element. As such, the error amplifier 162 can provide a higher level of signal to control the gate of the first transistor switch 161 to achieve the advantage of reducing the on-resistance of the first transistor switch 161. The error amplifier 162 receives a reference voltage signal Vr at the non-inverting input terminal, and receives a current detecting signal IFB generated by the first detecting unit at the inverting input terminal, and accordingly achieves the function of feedback compensation. The state of the first transistor switch 161 is controlled. The current modulation unit 166 includes a second power switch 163, a second detection unit Rx2, and an impedance unit. The second end of the body switch 163 is coupled to the first transistor switch 161 and the first detector. The connection point of the test unit 70 is connected to the ground through the second detecting unit Rr2, and the control end receives the mode switching signal Ssw through the impedance unit Rr3. In this embodiment, the second transistor switch is a two-carrier transistor and is switched according to a mode, and the number Ssw controls the magnitude of the current flowing through the current balancing terminal Dx. When the mode switching signal Ssw is at a low level, the second transistor switch 163 is turned off, and the current flowing through the current balance fDx flows through the first detecting unit Rrl to generate a current sense of the same level as the reference voltage signal Vr. The test signal IFB, at this time, flows through the current balance to know that the current value of the Dx is the _th current value. When the mode switching signal is high level 201143514 flat (four) ^ electric body open _163 is turned on and flows through a steady current, so that the current flowing through the current partially passes through the current modulation unit 166 and partially flows through the first debt V at this time.赦电辞衡^Dx's electrical hybrid is the second current throwing power f is shunted. 'Current_signal 1FB is still controlled by the 峨Vr (four) level, that is, the second current value is equal to the first current Yang flow current Change the current of unit 166. Therefore, through the current modulation single f i6 Λ ’ 使 使 使 使 使 使 使 使 使 使 使 使 使 使 使 使 使 使 使 使 魏 魏 魏 魏 魏 魏 魏In addition, in addition to the circuit structure of the current control element in the above embodiments, the current control element can also use other circuit structures with current sharing functions, such as a current mirror, to control the flow through each of the plurality of light emitting diodes. The current of the string is such that the current on the current balance terminal of each current control unit is almost the same. In addition to the purpose of adjusting the current detection signal to achieve the switching mode as in the above embodiment, the same switching mode function can be achieved by the reference voltage signal Vr, that is, the embodiment shown in the first figure can omit the resistance modulation. Unit 66, and the embodiment shown in the second figure may omit the current modulation unit 166. Referring to the third figure, there is shown a circuit diagram of a reference voltage generator in accordance with a preferred embodiment of the present invention. The reference voltage generator includes a current mirror 271, a first transistor switch 272, a second transistor switch 263, an error amplifier 273, a first detection early element 274, and reference resistors R1, R2, R3, R4. The reference resistors ri and R2 are connected in series between the power supply voltage VCC and the ground, and the reference resistor R3 is connected to the connection point of the reference resistors Ri and R2 through the second transistor switch 263 to generate a voltage dividing signal Vb to the error amplifier 273. To the input. The first transistor switch 272 is connected in series with the first detecting unit 274, and the connection point generates a current detecting signal Va to the inverting input terminal of the error amplifier 273. The error amplifier 273 outputs the §fl number at the output to control the equivalent resistance value of the first transistor switch 272, so that the level of the current detecting signal Va and the level of the voltage dividing signal Vb are equal to each other and then flow through the first The current of the detecting unit 274 is stable. The current mirror 271 is connected to the first detecting unit 274 through the first transistor switch 272, and the current mirror image is generated at the other end to generate the 201143514 with the first transistor switch 272. Flow through reference resistor R4 to produce a "reference", Vr. The second transistor switch 263 switches the current_signal Vb of the signal & ί according to a mode. When the mode cut-in number Ssw is on the level, the first transistor switch 263 is turned on, and the current pick-up signal Vb has a lower level. When the mode switching signal Ssw is at a low level, the lightning crystal switch 263 is turned off, and the current detecting signal % is at a higher level. Therefore, by adjusting the level of the current_signal Vb, the current flowing through the reference resistor 斛 can be adjusted, and then the reference voltage signal of different levels is generated. The reference voltage generated by the third reference voltage H′ is generated by the reference dragon signal Vr. To the non-inverting input of the error amplifier shown in the first and second figures. - Figure 4 is a circuit block diagram of a backlight module in accordance with a preferred embodiment of the present invention. The backlight module includes a conversion circuit 34A, a light emitting diode module, a current control element 360, a controller c〇N, and a voltage clamping unit 70 380. The conversion circuit 340 is coupled to an input power source Vin to convert the power of the input power source Vin into an output voltage v〇ut according to a control signal to activate the LED module 350. The controller C0N receives the voltage feedback signal FB representing the output voltage v〇ut to stabilize the voltage value of the output voltage v〇ut, and adjusts the brightness of the LED module 35 according to a dimming signal DIM. The current control component 360 corresponds to the LED string in the LED module 350 through at least one current balancing terminal Dx to stabilize the current flowing through the LED module po. In addition, the current control component 36 〇 according to a mode switching signal Ssw ′ when the mode switching signal Ssw represents a first mode, controlling the current flowing through the LED module 350 to a first current value, in mode switching When the signal Ssw represents a second mode, the current flowing through the LED module 35 is controlled to a second current value. The voltage clamping unit 38 is coupled to the current balancing terminal Dx of the LED module 350 to clamp the voltage of the current balancing terminal, that is, the voltage across the current control component 360, within a voltage value. In this embodiment, the voltage clamping unit 380 may include at least one resistor corresponding to the at least one current balancing terminal Dx′, so that when the dimming signal DIM represents off, the corresponding LED in the LED module 350 The voltage of the body string falls near the driving end Dx^ of the illuminated 201143514, thereby preventing the LED module 35 from being read as the system of the present invention. I would like to make it clear that the track and the invention of the embodiment fully comply with the requirements of the patent three: novelty, advance 2 if ίίί, it should be understood that the embodiment is turned to depict the invention: [Simple description of the figure] The schematic diagram of the driving circuit of the light emitting diode of the present invention. The second figure is a schematic diagram of a current path of the current control element according to the invention. The third figure is a schematic diagram of a reference voltage generator circuit in accordance with the present invention. The fourth figure is a circuit block diagram of a backlight module according to the present invention. [Main component symbol description] The present invention: Conversion circuit 340 Light-emitting diode module 50 > 350 Current control element 60 > 360 First transistor switch 61, 161, 272 Error amplifier 62, 162, 273 First transistor Switch 63, 163, 263 Current control unit 65, 165 Current modulation unit 66 ' 166 Current mirror 271 First detection unit Rrl, 274 Second detection unit Rr2 201143514 Reference resistance R1 > R2 ' R3 ' R4 Impedance unit Rr3 Voltage clamping unit 380 Controller CON Current detection signal Va Voltage division signal Vb Mode switching signal Ssw Driving voltage VDDH Power supply voltage VDDL > VCC Input power Yin Output power supply voltage feedback signal Current detection signal Dimming signal Current balance terminal reference voltage Signal
VoutVout
FBFB
IFBIFB
DIM D1 〜Dn、Dx VrDIM D1 ~Dn, Dx Vr