TW201603633A

TW201603633A - LED backlight driving device

Info

Publication number: TW201603633A
Application number: TW103122920A
Authority: TW
Inventors: 詹作晟; 李俊欣; 邱霖宏; 張偉勛; 王璽瑞
Original assignee: 盛群半導體股份有限公司
Priority date: 2014-07-02
Filing date: 2014-07-02
Publication date: 2016-01-16
Also published as: TWI527496B

Abstract

A LED backlight driving device used to drive a LED circuit includes a control module, an error amplifier and an adjusting module. The control module receives a first dimming signal, an error signal and a sensing signal from the LED circuit. The error amplifier receives a reference signal and a feedback signal from the LED circuit, and outputs the error signal. The adjusting module receives the first dimming signal and the feedback signal, and outputs the reference signal. Each periods of the first dimming signal includes an ON-time and an OFF-time. During the ON-time, the potential of the reference signal rises to a reference potential with time. While during the OFF-time, the potential of the reference signal follows the potential of the feedback signal.

Description

發光二極體背光驅動裝置Light-emitting diode backlight driving device

本發明是一種背光驅動裝置，特別是一種具高線性調光的發光二極體背光驅動裝置。The invention is a backlight driving device, in particular to a light-emitting diode backlight driving device with high linearity dimming.

請參閱第1圖，為習知發光二極體背光驅動系統之概要示意圖。於一般操作下，當調光訊號CN為高電位（邏輯“1”）時，發光二極體背光驅動系統1會正常操作，而當調光訊號CN為低電位（邏輯“0”）時，發光二極體背光驅動系統1會停止對發光二極體LED供電。其中，當調光訊號CN由低電位轉態為高電位時，發光二極體LED上的低電流會使回授訊號V_f 之電位低下而與參考電壓V_r 之電位差距過大，進而促使誤差放大器12產生過多的補償電流I_e ，並使得控制電路11產生較大的工作週期。因此，於電感L上會感應出較高的突波電流，且突波電流流經發光二極體LED上而造成輸出電壓V_O 產生非預期的大電壓。Please refer to FIG. 1 , which is a schematic diagram of a conventional LED backlight driving system. Under normal operation, when the dimming signal CN is high (logic "1"), the LED backlight driving system 1 will operate normally, and when the dimming signal CN is low (logic "0"), The LED backlight driving system 1 stops supplying power to the LEDs. Wherein, when the dimming signal CN is turned from a low potential to a high potential, the low current on the LED of the LED causes the potential of the feedback signal V _{f to} be lowered and the potential difference with the reference voltage V _r is too large, thereby causing an error. amplifier 12 generates excessive compensation current I _e, and the control circuit 11 so that a greater duty cycle. Therefore, a high surge current is induced on the inductor L, and a surge current flows through the LED of the LED to cause an undesirably large voltage of the output voltage V _O .

此外，當調光訊號CN為低電位時，位於輸出端的穩壓電容C_O 會對發光二極體LED放電，且當調光訊號CN的切換頻率變快時，位於輸出端的穩壓電容C_O 對發光二極體LED放電所造成之影響便會加劇。此乃因為當調光訊號CN的切換頻率變快時亦代表穩壓電容C_O 可放電之時間被縮短，而致使穩壓電容C_O 上之殘餘電流於調光訊號CN的切換時間內無完全流光（即，於調光訊號CN關閉時，穩壓電容C_O 開始對發光二極體LED放電，但尚未放完電時調光訊號CN又被開啟）。因此，造成在調光訊號CN關閉時仍會有殘餘電流通過發光二極體LED，而影響到調光的線性度。In addition, when the dimming signal CN is low, the voltage stabilizing capacitor C _O at the output end discharges the LED of the LED, and when the switching frequency of the dimming signal CN becomes faster, the voltage stabilizing capacitor C _O at the output end The effect on the discharge of LEDs is exacerbated. This is because when the switching frequency of the dimming signal CN becomes faster, the time during which the voltage stabilizing capacitor C _O can be discharged is shortened, and the residual current on the voltage stabilizing capacitor C _O is not completely completed during the switching time of the dimming signal CN. Streaming (ie, when the dimming signal CN is turned off, the stabilizing capacitor C _O starts to discharge the LED of the LED, but the dimming signal CN is turned on again when the power is not discharged). Therefore, when the dimming signal CN is turned off, residual current still passes through the LEDs, which affects the linearity of the dimming.

有鑑於此，本發明提出一種發光二極體背光驅動裝置，當調光訊號由低電位轉態至高電位時，藉由調整模組調整並減緩流經發光二極體的電流，以平衡當調光訊號為低電位時殘餘電流所造成的影響，且減少突波電流的產生，來提高調光的線性度。In view of the above, the present invention provides a backlight driving device for a light-emitting diode. When the dimming signal is switched from a low potential to a high potential, the adjustment module adjusts and slows the current flowing through the light-emitting diode to balance the adjustment. The optical signal is the effect of residual current at low potential, and reduces the generation of surge current to improve the linearity of dimming.

本發明之其中之一概念為一種發光二極體背光驅動裝置，用以驅動發光二極體電路，此發光二極體背光驅動裝置包括控制模組、誤差放大器與調整模組。其中，控制模組接收第一調光訊號、誤差訊號與來自發光二極體電路的感測訊號，並根據所接收的第一調光訊號、誤差訊號與感測訊號來產生控制訊號至發光二極體電路。誤差放大器之負向端接收來自發光二極體電路的回授訊號，誤差放大器之正向端接收參考訊號，且誤差放大器根據所接收的回授訊號與參考訊號來輸出誤差訊號。調整模組接收第一調光訊號與回授訊號，並根據第一調光訊號與回授訊號輸出參考訊號，其中第一調光訊號之每一週期包括一導通期間和一截止期間，當第一調光訊號於導通期間時，參考訊號之電位隨時間提升至一參考電位，而當第一調光訊號於截止期間時，參考訊號之電位追隨回授訊號之電位。One of the concepts of the present invention is a light-emitting diode backlight driving device for driving a light-emitting diode circuit. The light-emitting diode backlight driving device includes a control module, an error amplifier and an adjustment module. The control module receives the first dimming signal, the error signal, and the sensing signal from the LED circuit, and generates a control signal to the light emitting according to the received first dimming signal, the error signal and the sensing signal. Polar body circuit. The negative end of the error amplifier receives the feedback signal from the LED circuit, the forward end of the error amplifier receives the reference signal, and the error amplifier outputs the error signal according to the received feedback signal and the reference signal. The adjustment module receives the first dimming signal and the feedback signal, and outputs a reference signal according to the first dimming signal and the feedback signal, wherein each period of the first dimming signal includes an on period and a off period, when the first When the dimming signal is in the on period, the potential of the reference signal is raised to a reference potential with time, and when the first dimming signal is in the off period, the potential of the reference signal follows the potential of the feedback signal.

綜上所述，根據本發明之發光二極體背光驅動裝置，藉由調整模組來控制誤差放大器所接收的參考訊號，以減緩發光二極體於調光訊號由低電位轉態為高電位時所流經的電流，來平衡當調光訊號為低電位時穩壓電容對發光二極體放電所造成之殘餘電流影響，且於調光訊號切為低電位時，誤差放大器之二輸入端不會有大電壓差產生，因而可成功達到減少突波電流與增加調光電流之線性度。In summary, according to the LED backlight driving device of the present invention, the reference signal received by the error amplifier is controlled by the adjustment module to slow down the dimming of the LED from the low potential to the high potential. The current flowing through to balance the residual current caused by the voltage-suppressing capacitor on the discharge of the light-emitting diode when the dimming signal is low, and the second input of the error amplifier when the dimming signal is cut to a low potential There is no large voltage difference, so the linearity of reducing the surge current and increasing the dimming current can be successfully achieved.

以下在實施方式中詳細敘述本發明之詳細特徵及優點，其內容足以使任何熟習相關技藝者瞭解本發明之技術內容並據以實施，且根據本說明書所揭露之內容、申請專利範圍及圖式，任何熟習相關技藝者可輕易地理解本發明相關之目的及優點。The detailed features and advantages of the present invention are described in detail in the embodiments of the present invention. The objects and advantages associated with the present invention can be readily understood by those skilled in the art.

請參閱第2圖，為本發明一實施例之發光二極體背光驅動裝置之概要示意圖，揭露用以驅動發光二極體電路3之一發光二極體背光驅動裝置2，包含控制模組21、誤差放大器22與調整模組23。2 is a schematic diagram of a backlight manufacturing device for a light-emitting diode according to an embodiment of the present invention, and discloses a backlight driving device 2 for driving a light-emitting diode circuit 3, including a control module 21 The error amplifier 22 and the adjustment module 23.

控制模組21的一控制端電性連接至前級電路（圖未示），並接收來自前級電路的第一調光訊號DIM1。控制模組21的一感測端電性連接至發光二極體電路3，並接收來自發光二極體電路3的感測訊號I_S 。控制模組21的一輸入端電性連接至誤差放大器22的輸出端，並接收來自誤差放大器22的誤差訊號I_err 。控制模組21的一輸出端電性連接至發光二極體電路3，並輸出一控制訊號V_c 至發光二極體電路3。A control terminal of the control module 21 is electrically connected to the front stage circuit (not shown) and receives the first dimming signal DIM1 from the front stage circuit. A sensing end of the control module 21 is electrically connected to the LED circuit 3 and receives the sensing signal I _S from the LED circuit 3. An input terminal of the control module 21 is electrically connected to the output of the error amplifier 22, and receives an error signal I _err from the error amplifier 22. An output end of the control module 21 is electrically connected to the LED circuit 3 and outputs a control signal V _c to the LED circuit 3.

調整模組23的一控制端電性連接至前級電路（圖未示），並接收來自前級電路的第一調光訊號DIM1。調整模組23的一輸入端電性連接至誤差放大器22的負向端與發光二極體電路3，並接收來自發光二極體電路32的回授訊號V_fb 。誤差放大器22的正向端電性連接至調整模組23的一輸出端，並接收來自調整模組23的參考訊號V_ref 。A control terminal of the adjustment module 23 is electrically connected to the front stage circuit (not shown) and receives the first dimming signal DIM1 from the front stage circuit. An input terminal of the adjustment module 23 is electrically connected to the negative terminal of the error amplifier 22 and the LED circuit 3, and receives the feedback signal V _fb from the LED circuit 32. The forward end of the error amplifier 22 is electrically connected to an output of the adjustment module 23 and receives the reference signal V _ref from the adjustment module 23 .

在本實施例中，第一調光訊號DIM1用以控制控制模組21輸出控制訊號V_c 與否，藉以控制發光二極體電路3之啟閉。其中，第一調光訊號DIM1為數位訊號，且第一調光訊號DIM1之每一週期皆包含導通期間ON和截止期間OFF，如第5圖所示。於此，以第一調光訊號DIM1於高電位之狀態作為導通期間ON，並以第一調光訊號DIM1於低電位之狀態作為截止期間OFF來進行以下的所有說明，然本發明並不以此為限。此外，第一調光訊號DIM1之責任週期（Duty Cycle）等同於其導通期間ON佔其週期的百分比。於此，以第一調光訊號DIM1之責任週期寬度為50%，即以導通時間ON為1/2週期為例進行說明，然本發明並不以此為限，第一調光訊號DIM1之責任週期端視調光亮度之需求而定。In this embodiment, the first dimming signal DIM1 is used to control whether the control module 21 outputs the control signal V _c or not to control the opening and closing of the LED circuit 3 . The first dimming signal DIM1 is a digital signal, and each period of the first dimming signal DIM1 includes an ON period during the ON period and an OFF period during the OFF period, as shown in FIG. 5. Here, the first dimming signal DIM1 is turned on during the high-potential state, and all of the following descriptions are made with the first dimming signal DIM1 being turned off during the low-potential state. However, the present invention does not This is limited. In addition, the Duty Cycle of the first dimming signal DIM1 is equivalent to the percentage of ON during its ON period. In this case, the duty cycle width of the first dimming signal DIM1 is 50%, that is, the ON time is 1/2 cycle as an example, but the invention is not limited thereto, and the first dimming signal DIM1 The duty cycle depends on the need for dimming brightness.

請搭配參閱第2圖與第5圖，當第一調光訊號DIM1於導通期間ON時，發光二極體電路3開啟並發光，且調整模組23輸出之參考訊號V_ref 的電位會隨時間緩緩充電提升至一參考電位V1。而當第一調光訊號DIM1於截止期間OFF時，發光二極體電路3關閉而不發光，且參考訊號V_ref 的電位將會追隨回授訊號V_fb 的電位，即，此時參考訊號V_ref 的電位將會隨回授訊號V_fb 的電位變化而變化，以避免在第一調光訊號DIM1由截止期間OFF切換為導通期間ON時，誤差放大器之二輸入端的電位相差過大而輸出過大的誤差訊號I_err ，造成發光二極體電路3產生突波電流而影響發光二極體電路3的發光品質。Please refer to FIG. 2 and FIG. 5 , when the first dimming signal DIM1 is ON during the on period, the LED circuit 3 is turned on and emits light, and the potential of the reference signal V _ref output by the adjustment module 23 is timed. The slow charge is raised to a reference potential V1. When the first dimming signal DIM1 is OFF during the off period, the LED circuit 3 is turned off and does not emit light, and the potential of the reference signal V _ref will follow the potential of the feedback signal V _fb , that is, the reference signal V at this time. The potential of _ref will change with the potential change of the feedback signal V _fb to avoid the potential difference between the two input terminals of the error amplifier being too large and the output being too large when the first dimming signal DIM1 is switched from OFF to ON during the off period. The error signal I _err causes the illuminating diode circuit 3 to generate a glancing current to affect the illuminating quality of the illuminating diode circuit 3.

請參閱第3圖，為本發明一實施例之發光二極體背光驅動裝置驅動一發光二極體電路之概要示意圖，茲一一詳述如下。Please refer to FIG. 3 , which is a schematic diagram of driving a light-emitting diode circuit of a light-emitting diode backlight driving device according to an embodiment of the present invention, which is described in detail below.

首先，介紹控制模組21。控制模組21包括震盪器211、斜率補償器212、比較器213、閂鎖器214與驅動器215。First, the control module 21 will be described. The control module 21 includes an oscillator 211, a slope compensator 212, a comparator 213, a latch 214, and a driver 215.

其中，斜率補償器212的一輸入端電性連接至發光二極體電路3，並接收來自發光二極體電路3的感測訊號I_S 。比較器213的正向端電性連接至斜率補償器212的輸出端，並接收來自斜率補償器212的補償訊號V_s 。比較器213的負向端電性連接至誤差放大器22的輸出端，並接收來自誤差放大器22的誤差訊號I_err 。閂鎖器214的設定端電性連接至震盪器211的輸出端，並接收來自震盪器的時脈訊號。閂鎖器214的設定端電性連接至比較器213的輸出端，並接收來自比較器213的比較訊號。驅動器215的一輸入端電性連接至閂鎖器214的輸出端，並接收來自閂鎖器214的驅動訊號。驅動器215的一控制端電性連接至前級電路（圖未示），並接收來自前級電路的第一調光訊號DIM1。驅動器215的輸出端電性連接至發光二極體電路3，並輸出控制訊號V_c 至發光二極體電路3。Wherein an input terminal of the slope compensator 212 is electrically connected to the light emitting diode circuit 3, and receives a sensing signal I _S from the 3 light-emitting diode circuit. The forward terminal of the comparator 213 is electrically coupled to the output of the slope compensator 212 and receives the compensation signal V _s from the slope compensator 212. The negative terminal of the comparator 213 is electrically coupled to the output of the error amplifier 22 and receives the error signal I _err from the error amplifier 22. The set end of the latch 214 is electrically connected to the output of the oscillator 211 and receives a clock signal from the oscillator. The set terminal of the latch 214 is electrically connected to the output of the comparator 213 and receives the comparison signal from the comparator 213. An input of the driver 215 is electrically connected to the output of the latch 214 and receives a driving signal from the latch 214. A control terminal of the driver 215 is electrically connected to the front stage circuit (not shown) and receives the first dimming signal DIM1 from the front stage circuit. Output terminal of driver 215 is electrically connected to the light emitting diode circuit 3, and outputs a control signal V _c to the light emitting diode circuit 3.

請參閱第4圖，為本發明之斜率補償器之一實施例之概要示意圖，揭露一斜率補償器212包含電流感測電路2121與電流至電壓轉換電路2122。其中，電流感測電路2121之一輸入端電性連接至發光二極體電路3，並接收來自發光二極體電路3的感測訊號I_S 。電流至電壓轉換電路2122之一輸入端電性連接至電流感測電路2121之輸出端，並接收來自電流感測電路2121之感測電流，且電流至電壓轉換電路2122之輸出端電性連接至比較器213之正向端，並根據此感測電流輸出補償訊號V_s 至比較器213之正向端。Please refer to FIG. 4 , which is a schematic diagram of an embodiment of a slope compensator of the present invention. A slope compensator 212 includes a current sensing circuit 2121 and a current to voltage conversion circuit 2122 . The input end of the current sensing circuit 2121 is electrically connected to the LED circuit 3 and receives the sensing signal I _S from the LED circuit 3. An input end of the current-to-voltage conversion circuit 2122 is electrically connected to the output end of the current sensing circuit 2121, and receives the sensing current from the current sensing circuit 2121, and the output of the current-to-voltage conversion circuit 2122 is electrically connected to The forward end of the comparator 213 outputs a compensation signal V _s to the forward end of the comparator 213 according to the sense current.

此外，控制模組21更包含第五電阻R5與第三電容C3。其中，第五電阻R5之第一端電性連接至比較器213的負向端，第五電阻R5之第二端電性連接至第三電容C3之第一端，且第三電容C3之第二端電性連接至地。In addition, the control module 21 further includes a fifth resistor R5 and a third capacitor C3. The first end of the fifth resistor R5 is electrically connected to the negative end of the comparator 213, the second end of the fifth resistor R5 is electrically connected to the first end of the third capacitor C3, and the third capacitor C3 The two ends are electrically connected to the ground.

復參閱第3圖，以介紹調整模組23。調整模組23包括反相器inv、第一電容C1、第一電阻R1、第一開關S1、第二電阻R2與第二開關S2。Referring to Figure 3, the adjustment module 23 will be described. The adjustment module 23 includes an inverter inv, a first capacitor C1, a first resistor R1, a first switch S1, a second resistor R2, and a second switch S2.

其中，反相器inv的輸入端電性連接至前級電路（圖未示），並接收來自前級電路的第一調光訊號DIM1。第一開關S1之控制端電性連接至前級電路（圖未示），並接收來自前級電路的第一調光訊號DIM1。第一開關S1之第二端電性連接至一參考電位V1。第一電阻R1之第二端電性連接至第一開關S1之第一端，且第一電阻R1之第一端電性連接至第一節點N1。第一電容C1之第一端電性連接至地，且第一電容C1之第二端電性連接至第一節點N1。第二電阻R2之第一端電性連接至第一節點N1，且第二電阻R2之第二端電性連接至第二開關S2之第一端。第二開關S2之控制端電性連接至反相器inv的輸出端，並接收來自反相器inv的第二調光訊號DIM2。The input end of the inverter inv is electrically connected to the front stage circuit (not shown), and receives the first dimming signal DIM1 from the front stage circuit. The control terminal of the first switch S1 is electrically connected to the front stage circuit (not shown) and receives the first dimming signal DIM1 from the front stage circuit. The second end of the first switch S1 is electrically connected to a reference potential V1. The second end of the first resistor R1 is electrically connected to the first end of the first switch S1, and the first end of the first resistor R1 is electrically connected to the first node N1. The first end of the first capacitor C1 is electrically connected to the ground, and the second end of the first capacitor C1 is electrically connected to the first node N1. The first end of the second resistor R2 is electrically connected to the first node N1, and the second end of the second resistor R2 is electrically connected to the first end of the second switch S2. The control terminal of the second switch S2 is electrically connected to the output of the inverter inv and receives the second dimming signal DIM2 from the inverter inv.

接續，誤差放大器22之正向端電性連接至第一節點N1，並接收來自第一節點N1的參考訊號V_ref 。誤差放大器22之負向端電性連接至第二開關S2之第二端與發光二極體電路3之一輸出端，並接收來自發光二極體電路3的回授訊號V_fb 。Next, the forward end of the error amplifier 22 is electrically connected to the first node N1, and receives the reference signal V _ref from the first node N1. The negative terminal of the error amplifier 22 is electrically connected to the second end of the second switch S2 and one of the output terminals of the LED circuit 3, and receives the feedback signal V _fb from the LED circuit 3.

於此，當第一開關S1導通且第二開關S2開路時，第一節點N1之電位可藉由第一電位V1經由第一電阻R1與第一電容C1慢慢充電至第一電位。而當第一開關S1開路且第二開關S2導通時，第一節點N1之電位將隨回授訊號V_fb 變化。此外，第二電阻R2是用以防止雜訊，故其使用之電阻值較低。Here, when the first switch S1 is turned on and the second switch S2 is open, the potential of the first node N1 can be slowly charged to the first potential via the first resistor R1 and the first capacitor C1 by the first potential V1. When the first switch S1 is open and the second switch S2 is turned on, the potential of the first node N1 will change with the feedback signal V _fb . In addition, the second resistor R2 is used to prevent noise, so the resistance value used is low.

最後，介紹發光二極體電路3。發光二極體電路3包括電感L、電晶體M1、第三電阻R3、第二電容C2、發光二極體LED與第四電阻R4。Finally, the light-emitting diode circuit 3 will be described. The light emitting diode circuit 3 includes an inductor L, a transistor M1, a third resistor R3, a second capacitor C2, a light emitting diode LED, and a fourth resistor R4.

其中，電感L之第一端電性連接至一電源電壓V2，且電感L之第二端電性連接至電晶體M1之第一端。電晶體M1之控制端電性連接至驅動器215之輸出端，並接收來自驅動器215的控制訊號V_c 。電晶體M1之第二端與第三電阻R3之第一端皆電性連接至一第二節點N2，且此第二節點N2亦電性連接至斜率補償器212的輸入端，以輸出感測訊號I_S 至斜率補償器212。第三電阻R3之第二端與第二電容C2之第一端電性連接至地，且第二電容C2之第二端電性連接至電感L之第二端、電晶體M1之第一端與發光二極體LED之第一端。第四電阻R4之第一端電性連接至地，且第四電阻R4之第二端與發光二極體LED之第二端皆電性連接至第三節點N3，並自第三節點N3回授至誤差放大器22的負向端，以輸出回授訊號V_fb 至誤差放大器22。The first end of the inductor L is electrically connected to a power supply voltage V2, and the second end of the inductor L is electrically connected to the first end of the transistor M1. The control terminal of the transistor M1 is connected to an output terminal of the driver 215, and receives a control signal V _c from the driver 215. The second end of the transistor M1 and the first end of the third resistor R3 are electrically connected to a second node N2, and the second node N2 is also electrically connected to the input end of the slope compensator 212 for output sensing. Signal I _S to slope compensator 212. The second end of the third resistor R3 is electrically connected to the first end of the second capacitor C2, and the second end of the second capacitor C2 is electrically connected to the second end of the inductor L, the first end of the transistor M1. The first end of the LED with the light emitting diode. The first end of the fourth resistor R4 is electrically connected to the ground, and the second end of the fourth resistor R4 and the second end of the LED are electrically connected to the third node N3, and are returned from the third node N3. The negative terminal of the error amplifier 22 is supplied to output the feedback signal V _fb to the error amplifier 22 .

於此，第二電容C2可稱為穩壓電容。此外，感測訊號I_S 為流經第三電阻R3之電流訊號，而第四電阻R4為發光二極體電流I_LED 之感應電阻，因此，回授訊號V_fb 為流經發光二極體LED之發光二極體電流I_LED 於第四電阻R4上所形成的電壓訊號。Here, the second capacitor C2 may be referred to as a voltage stabilizing capacitor. In addition, the sensing signal I _S is a current signal flowing through the third resistor R3, and the fourth resistor R4 is a sensing resistor of the _LED current I _LED . Therefore, the feedback signal V _fb is flowing through the LED. The _LED signal of the _LED current I _LED is formed on the fourth resistor R4.

另，發光二極體電路3更包含二極體D1耦接於電晶體M1之第一端與第二電容C2之第二端間。於此，二極體D1之第一端電性連接至電晶體M1之第一端，且二極體D1之第二端電性連接至第二電容C2之第二端。In addition, the LED circuit 3 further includes a diode D1 coupled between the first end of the transistor M1 and the second end of the second capacitor C2. The first end of the diode D1 is electrically connected to the first end of the transistor M1, and the second end of the diode D1 is electrically connected to the second end of the second capacitor C2.

請參閱第5圖，為本發明之第一調光訊號、發光二極體電流與平均電流的關係概要示意圖。由於已知當第一調光訊號DIM1處於截止期間OFF時，第二電容C2會以RC方式對發光二極體LED放電，即產生殘餘電流A通過發光二極體LED，此殘餘電流A如第5圖左斜區域部分所示。故本發明為了消除殘餘電流A對調光的線性度之影響，而利用一調整模組23來改變誤差放大器22所接收的參考訊號V_ref 之電位，即於調整模組23中使參考訊號V_ref 以RC充電方式充電至一參考的第一電位V1來平衡殘餘電流A的影響。Please refer to FIG. 5 , which is a schematic diagram showing the relationship between the first dimming signal, the LED current and the average current according to the present invention. It is known that when the first dimming signal DIM1 is OFF during the off period, the second capacitor C2 discharges the LED body in an RC manner, that is, generates a residual current A through the LED, and the residual current A is as 5 is shown in the left oblique section. Therefore, in order to eliminate the influence of the residual current A on the linearity of the dimming, the adjustment module 23 is used to change the potential of the reference signal V _ref received by the error amplifier 22, that is, the reference signal V is adjusted in the adjustment module 23. _ref RC charge charged in a manner to a first reference potential V1 to balance the influence of the residual current a.

由於當第一調光訊號DIM1處於導通期間ON時，參考訊號V_ref 之電位是以RC充電方式慢慢增加至第一電位V1，故發光二極體電流I_LED 亦以RC充電方式慢慢增加，而與原先習知的固定參考訊號V_ref 之方式相比，發光二極體電流I_LED 有部分電流B被消除，如第5圖右斜部分所示。因此，因此藉由第一調光訊號DIM1處於導通期間ON時減少部分電流B來補償當第一調光訊號DIM1處於截止期間OFF時殘餘電流A的影響，即可使發光二極體LED上之平均電流I_avg 維持於預設值，而達到高線性度的調光效果。When the first dimming signal DIM1 is ON during the ON period, the potential of the reference signal V _ref is gradually increased to the first potential V1 by the RC charging mode, so the LED current I _LED is gradually increased by the RC charging mode. , compared with the original conventional fixed reference signal V _ref of the embodiment, the light emitting diode current I _LED current part B is removed, as shown in FIG. 5 right oblique portion. Therefore, by reducing the partial current B when the first dimming signal DIM1 is in the ON period, the residual current A is compensated when the first dimming signal DIM1 is OFF during the off period, so that the LED can be made on the LED. The average current I _{avg is} maintained at a preset value to achieve a high linearity dimming effect.

綜上，復參閱第3圖，當第一調光訊號DIM1處於導通期間ON時，第一開關S1與第三開關S3導通，且由於第二調光訊號DIM2之相位相反於第一調光訊號DIM1，故由第二調光訊號DIM2控制之第二開關S2開路，因此，此時參考訊號V_ref 之電位會隨時間慢慢的以RC充電方式（於此，為利用第一電阻R1與第一電容C1）達到第一電位V1，故在穩定的情況下，此時發光二極體電流I_LED 由參考訊號V_ref 之電位除以第四電阻R4之值所決定。而當第一調光訊號DIM1開始切換為截止期間OFF時，第一開關S1與第三開關S3開路且第二開關S2導通，此時將會暫時切斷誤差放大器22並保留切換時的工作點，又，此時參考訊號V_ref 之電位會隨著回授訊號V_fb 之電位變化，故參考訊號V_ref 可藉由感測回授訊號V_fb 來得知發光二極體LED上之發光二極體電流I_LED ，因此，當第一調光訊號DIM1再次由截止期間OFF切換至導通期間ON時，參考訊號V_ref 之電位將會從回授訊號V_fb 之電位處開始慢慢以RC充電方式充電至第一電位V1，且發光二極體電流I_LED 亦隨參考訊號V_ref 之電位的增加方式慢慢增加至穩定電流，而可成功達到高線性度的調光效果。In summary, referring to FIG. 3, when the first dimming signal DIM1 is in the ON period, the first switch S1 and the third switch S3 are turned on, and since the phase of the second dimming signal DIM2 is opposite to the first dimming signal. DIM1, so the second switch S2 controlled by the second dimming signal DIM2 is open, therefore, the potential of the reference signal V _ref will be slowly charged with RC in time (in this case, the first resistor R1 and the first A capacitor C1) reaches the first potential V1, so in the case of stability, the _LED current I _{LED is} determined by dividing the potential of the reference signal V _ref by the value of the fourth resistor R4 . When the first dimming signal DIM1 starts to switch to the OFF period, the first switch S1 and the third switch S3 are open and the second switch S2 is turned on. At this time, the error amplifier 22 is temporarily cut off and the operating point at the time of switching is retained. Moreover, at this time, the potential of the reference signal V _ref changes with the potential of the feedback signal V _fb , so the reference signal V _ref can be used to sense the light-emitting diode on the LED of the LED by sensing the feedback signal V _fb . The body current I _LED , therefore, when the first dimming signal DIM1 is switched from the OFF period to the ON period, the potential of the reference signal V _ref will gradually start from the potential of the feedback signal V _fb by the RC charging mode. The battery is charged to the first potential V1, and the LED current I _LED is gradually increased to a stable current as the potential of the reference signal V _ref increases, and the high linearity dimming effect can be successfully achieved.

請參閱第6圖，為本發明另一實施例之發光二極體背光驅動裝置驅動一發光二極體電路之概要示意圖。在本實施例中，發光二極體背光驅動裝置2更包含一由運算放大器231。其中，運算放大器231之正向端電性連接至誤差放大器22之負向端與二極體發光電路3之第三節點N3，並接收來自第三節點N3的回授訊號V_fb 。運算放大器231之負向端與其輸出端皆電性連接至第二開關S2之第二端。Please refer to FIG. 6 , which is a schematic diagram of driving a light-emitting diode circuit of a light-emitting diode backlight driving device according to another embodiment of the present invention. In the embodiment, the LED backlight driving device 2 further includes an operational amplifier 231. Wherein the positive terminal of the operational amplifier 231 of the error amplifier 22 is connected to the negative terminal of the diode to the light emitting circuit 3 of the third node N3, and the feedback signal V _fb received from the third node N3. The negative terminal of the operational amplifier 231 and its output are electrically connected to the second terminal of the second switch S2.

於此，運算放大器231之負向端直接連接至其輸出端以構成一單增益緩衝器（Unit-Gain Buffer，或稱電壓隨耦器，Voltage Follower）之結構，來增強所接收的回授訊號V_fb ，並降低雜訊。Herein, the negative terminal of the operational amplifier 231 is directly connected to its output terminal to form a structure of a single gain buffer (Unit-Gain Buffer, or Voltage Follower) to enhance the received feedback signal. V _fb, and reduce noise.

請參閱第7圖，為依據本發明一實施例之發光二極體背光驅動裝置實施之責任週期變化對發光二極體電流變化之關係圖。可明顯看出依據本發明一實施例之發光二極體背光驅動裝置實施的發光二極體背光驅動器在第一調光訊號之頻率越高（如1KHz）的狀態下時，其發光二極體電流的線性度明顯較習知的發光二極體背光驅動裝置之線性度更好。Please refer to FIG. 7 , which is a diagram showing the relationship between the duty cycle change of the LED backlight driving device and the current change of the LED according to an embodiment of the invention. It can be clearly seen that the LED backlight driver implemented by the LED backlight driving device according to an embodiment of the present invention has a light-emitting diode when the frequency of the first dimming signal is higher (for example, 1 KHz). The linearity of the current is significantly better than that of the conventional LED backlight driver.

綜上所述，根據本發明之發光二極體背光驅動裝置，藉由調整模組來控制誤差放大器所接收的參考訊號，以減緩發光二極體於調光訊號由截止期間轉態為導通期間時所流經的電流，來平衡當第一調光訊號於截止期間時第二電容對發光二極體放電所造成之殘餘電流影響，且當第一調光訊號切換為截止期間時，誤差放大器之二輸入端不會有大電壓差產生，因而可成功達到減少突波電流與增加調光電流之線性度。In summary, according to the LED backlight driving device of the present invention, the reference signal received by the error amplifier is controlled by the adjustment module to slow down the period during which the dimming signal is turned from the off period to the on period during the off period. The current flowing through to balance the residual current caused by the discharge of the second capacitor to the light-emitting diode when the first dimming signal is turned off, and the error amplifier when the first dimming signal is switched to the off period The second input does not have a large voltage difference, so the linearity of reducing the surge current and increasing the dimming current can be successfully achieved.

本發明之技術內容已以較佳實施例揭示如上述，然其並非用以限定本發明，任何熟習此技藝者，在不脫離本發明之精神所做些許之更動與潤飾，皆應涵蓋於本發明之範疇內，因此本發明之保護範圍當視後附之申請專利範圍所界定者為準。The technical contents of the present invention have been disclosed in the preferred embodiments as described above, and are not intended to limit the present invention. Any modifications and refinements made by those skilled in the art without departing from the spirit of the present invention should be The scope of the invention is therefore defined by the scope of the appended claims.

1‧‧‧發光二極體背光驅動系統
11‧‧‧控制電路
12‧‧‧誤差放大器
2‧‧‧發光二極體背光驅動裝置
21‧‧‧控制模組
211‧‧‧震盪器
212‧‧‧斜率補償器
2121‧‧‧電流感測電路
2122‧‧‧電流至電壓轉換器
213‧‧‧比較器
214‧‧‧閂鎖器
215‧‧‧驅動器
22‧‧‧誤差放大器
23‧‧‧調整模組
231‧‧‧運算放大器
3‧‧‧發光二極體電路
A‧‧‧殘餘電流
B‧‧‧部分電流
CN‧‧‧調光訊號
C1‧‧‧第一電容
C2‧‧‧第二電容
C3‧‧‧第三電容
CO‧‧‧穩壓電容
D1‧‧‧二極體
DIM1‧‧‧第一調光訊號
DIM2‧‧‧第二調光訊號
inv‧‧‧反相器
Iavg‧‧‧平均電流
Ie‧‧‧補償電流
Ierr‧‧‧誤差訊號
ILED‧‧‧發光二極體電流
Is‧‧‧感測訊號
L‧‧‧電感
M1‧‧‧電晶體
N1‧‧‧第一節點
N2‧‧‧第二節點
N3‧‧‧第三節點
LED‧‧‧發光二極體
OFF‧‧‧截止期間
ON‧‧‧導通期間
R1‧‧‧第一電阻
R2‧‧‧第二電阻
R3‧‧‧第三電阻
R4‧‧‧第四電阻
R5‧‧‧第五電阻
S1‧‧‧第一開關
S2‧‧‧第二開關
S3‧‧‧第三開關
V1‧‧‧參考電位
V2‧‧‧電源電壓
Vf‧‧‧回授訊號
Vfb‧‧‧回授訊號
VO‧‧‧輸出電壓
Vr‧‧‧參考電壓
Vref‧‧‧參考訊號
Vs‧‧‧補償訊號
V_c‧‧‧控制訊號1‧‧‧Lighting diode backlight drive system
11‧‧‧Control circuit
12‧‧‧Error amplifier
2‧‧‧Lighting diode backlight driver
21‧‧‧Control Module
211‧‧‧ oscillator
212‧‧‧Slope compensator
2121‧‧‧ Current sensing circuit
2122‧‧‧Current to voltage converter
213‧‧‧ Comparator
214‧‧‧Latch
215‧‧‧ drive
22‧‧‧Error amplifier
23‧‧‧Adjustment module
231‧‧‧Operational Amplifier
3‧‧‧Lighting diode circuit
A‧‧‧Residual current
B‧‧‧Partial current
CN‧‧‧ dimming signal
C1‧‧‧first capacitor
C2‧‧‧second capacitor
C3‧‧‧ third capacitor
CO‧‧‧Stabilized capacitor
D1‧‧‧ diode
DIM1‧‧‧First dimming signal
DIM2‧‧‧ second dimming signal
Inv‧‧‧Inverter
Iavg‧‧‧Average current
Ie‧‧‧Compensation current
Ierr‧‧‧ error signal
ILED‧‧‧Light Diode Current
Is‧‧‧Sensing signal
L‧‧‧Inductance
M1‧‧‧O crystal
N1‧‧‧ first node
N2‧‧‧ second node
N3‧‧‧ third node
LED‧‧‧Light Emitting Diode
OFF‧‧‧ deadline
ON‧‧‧During
R1‧‧‧first resistance
R2‧‧‧second resistance
R3‧‧‧ third resistor
R4‧‧‧fourth resistor
R5‧‧‧ fifth resistor
S1‧‧‧ first switch
S2‧‧‧ second switch
S3‧‧‧ third switch
V1‧‧‧ reference potential
V2‧‧‧Power supply voltage
Vf‧‧‧ feedback signal
Vfb‧‧‧ feedback signal
VO‧‧‧ output voltage
Vr‧‧‧reference voltage
Vref‧‧‧ reference signal
Vs‧‧‧compensation signal
V _c ‧‧‧ control signal

[第1圖]為習知發光二極體背光驅動系統之概要示意圖。 [第2圖]為本發明一實施例之發光二極體背光驅動裝置之概要示意圖。 [第3圖]為本發明一實施例之發光二極體背光驅動裝置驅動一發光二極體電路之概要示意圖。 [第4圖]為本發明之斜率補償器之一實施例之概要示意圖。 [第5圖] 為本發明之第一調光訊號、發光二極體電流與平均電流的關係概要示意圖。 [第6圖] 為本發明另一實施例之發光二極體背光驅動裝置驅動一發光二極體電路之概要示意圖。 [第7圖] 為依據本發明一實施例之發光二極體背光驅動裝置實施之責任週期變化對發光二極體電流變化之關係圖。[Fig. 1] is a schematic diagram of a conventional light-emitting diode backlight driving system. [Fig. 2] Fig. 2 is a schematic view showing a light-emitting diode backlight driving device according to an embodiment of the present invention. [Fig. 3] Fig. 3 is a schematic diagram showing the driving of a light-emitting diode circuit by a light-emitting diode backlight driving device according to an embodiment of the present invention. [Fig. 4] is a schematic diagram showing an embodiment of a slope compensator of the present invention. [Fig. 5] is a schematic diagram showing the relationship between the first dimming signal, the light emitting diode current and the average current of the present invention. [FIG. 6] FIG. 6 is a schematic diagram showing the driving of a light-emitting diode circuit by a light-emitting diode backlight driving device according to another embodiment of the present invention. [Fig. 7] is a graph showing the relationship between the duty cycle change of the light-emitting diode backlight driving device and the change of the light-emitting diode current according to an embodiment of the present invention.

2‧‧‧發光二極體背光驅動裝置 2‧‧‧Lighting diode backlight driver

211‧‧‧震盪器 211‧‧‧ oscillator

212‧‧‧斜率補償器 212‧‧‧Slope compensator

213‧‧‧比較器 213‧‧‧ Comparator

214‧‧‧閂鎖器 214‧‧‧Latch

215‧‧‧驅動器 215‧‧‧ drive

22‧‧‧誤差放大器 22‧‧‧Error amplifier

3‧‧‧發光二極體電路 3‧‧‧Lighting diode circuit

C1‧‧‧第一電容 C1‧‧‧first capacitor

C2‧‧‧第二電容 C2‧‧‧second capacitor

C3‧‧‧第三電容 C3‧‧‧ third capacitor

D1‧‧‧二極體 D1‧‧‧ diode

DIM1‧‧‧第一調光訊號 DIM1‧‧‧First dimming signal

DIM2‧‧‧第二調光訊號 DIM2‧‧‧ second dimming signal

inv‧‧‧反相器 Inv‧‧‧Inverter

I_err‧‧‧誤差訊號 I _err ‧‧‧ error signal

I_LED‧‧‧發光二極體電流 I _LED ‧‧‧Lighting diode current

I_s‧‧‧感測訊號 I _s ‧ ‧ Sense signal

L‧‧‧電感 L‧‧‧Inductance

M1‧‧‧電晶體 M1‧‧‧O crystal

N1‧‧‧第一節點 N1‧‧‧ first node

N2‧‧‧第二節點 N2‧‧‧ second node

N3‧‧‧第三節點 N3‧‧‧ third node

LED‧‧‧發光二極體 LED‧‧‧Light Emitting Diode

R1‧‧‧第一電阻 R1‧‧‧first resistance

R2‧‧‧第二電阻 R2‧‧‧second resistance

R3‧‧‧第三電阻 R3‧‧‧ third resistor

R4‧‧‧第四電阻 R4‧‧‧fourth resistor

R5‧‧‧第五電阻 R5‧‧‧ fifth resistor

S1‧‧‧第一開關 S1‧‧‧ first switch

S2‧‧‧第二開關 S2‧‧‧ second switch

S3‧‧‧第三開關 S3‧‧‧ third switch

V1‧‧‧參考電位 V1‧‧‧ reference potential

V2‧‧‧電源電壓 V2‧‧‧Power supply voltage

V_fb‧‧‧回授訊號 V _fb ‧‧‧request signal

V_ref‧‧‧參考訊號 V _ref ‧‧‧ reference signal

V_c‧‧‧控制訊號 V _c ‧‧‧ control signal

Claims

一種發光二極體背光驅動裝置，用以驅動一發光二極體電路，該發光二極體背光驅動裝置包括：一控制模組，接收一第一調光訊號、一誤差訊號與來自該發光二極體電路的一感測訊號，並根據該第一調光訊號、該誤差訊號與該感測訊號產生一控制訊號至該發光二極體電路；一誤差放大器，該誤差放大器之負向端接收來自該發光二極體電路的一回授訊號，該誤差放大器之正向端接收一參考訊號，該誤差放大器根據該回授訊號與該參考訊號輸出該誤差訊號；及一調整模組，接收該第一調光訊號與該回授訊號，並根據該第一調光訊號與該回授訊號輸出該參考訊號，其中該第一調光訊號之每一週期包括一導通期間和一截止期間，當該第一調光訊號於該導通期間時，該參考訊號之電位隨時間提升至一參考電位，而當該第一調光訊號於該截止期間時，該參考訊號之電位追隨該回授訊號之電位。A light-emitting diode backlight driving device for driving a light-emitting diode circuit, the LED backlight driving device comprising: a control module, receiving a first dimming signal, an error signal, and the light-emitting diode a sensing signal of the polar body circuit, and generating a control signal to the LED circuit according to the first dimming signal, the error signal and the sensing signal; an error amplifier, the negative end receiving of the error amplifier a feedback signal from the LED circuit, the forward end of the error amplifier receives a reference signal, the error amplifier outputs the error signal according to the feedback signal and the reference signal; and an adjustment module receives the signal a first dimming signal and the feedback signal, and outputting the reference signal according to the first dimming signal and the feedback signal, wherein each period of the first dimming signal includes a conducting period and an off period, when When the first dimming signal is in the on period, the potential of the reference signal is raised to a reference potential with time, and when the first dimming signal is in the off period, the reference The potential number of follow the feedback signal of potential.

如請求項1所述的發光二極體背光驅動裝置，其中該控制模組包括：一震盪器，產生一時脈訊號；一斜率補償器，接收該感測訊號，並根據該感測訊號輸出一補償訊號；一比較器，該比較器之負向端接收該誤差訊號，該比較器之正向端接收該補償訊號，該比較器比較該誤差訊號與補償訊號並輸出一比較訊號；一閂鎖器，該閂鎖器之設定端接收該時脈訊號，該閂鎖器之重置端接收該比較訊號，該閂鎖器根據該時脈訊號與該比較訊號輸出一驅動訊號；及一驅動器，接收該驅動訊號與該第一調光訊號，並根據該驅動訊號與該第一調光訊號輸出該控制訊號。The illuminating diode backlight driving device of claim 1, wherein the control module comprises: an oscillator that generates a clock signal; a slope compensator that receives the sensing signal and outputs a sensing signal according to the sensing signal a comparator, the negative end of the comparator receives the error signal, the forward end of the comparator receives the compensation signal, the comparator compares the error signal with the compensation signal and outputs a comparison signal; The setting end of the latch receives the clock signal, the reset end of the latch receives the comparison signal, and the latch outputs a driving signal according to the clock signal and the comparison signal; and a driver, Receiving the driving signal and the first dimming signal, and outputting the control signal according to the driving signal and the first dimming signal.

如請求項1所述的發光二極體背光驅動裝置，其中該調整模組包括：一反相器，接收該第一調光訊號，並輸出一第二調光訊號，其中該第二調光訊號之相位與該第一調光訊號之相位相反；一第一電容，該第一電容之第一端接地，且該第一電容之第二端連接至一第一節點；一第一電阻，該第一電阻之第一端連接至該第一節點；一第一開關，由該第一調光訊號控制，該第一開關之第一端連接該第一電阻之第二端，且該第一開關之第二端連接該參考電位；一第二電阻，該第二電阻之第一端連接該第一節點，且該第一節點連接至該誤差放大器之正向端以輸出該參考訊號；及一第二開關，由該第二調光訊號控制，該第二開關之第一端連接該第二電阻之第二端，該第二開關之第二端連接至該誤差放大器之負向端。The illuminating diode backlight driving device of claim 1, wherein the adjusting module comprises: an inverter, receiving the first dimming signal, and outputting a second dimming signal, wherein the second dimming The phase of the signal is opposite to the phase of the first dimming signal; a first capacitor, the first end of the first capacitor is grounded, and the second end of the first capacitor is connected to a first node; a first resistor, a first end of the first resistor is connected to the first node; a first switch is controlled by the first dimming signal, a first end of the first switch is connected to a second end of the first resistor, and the first end a second end of the switch is connected to the reference potential; a second resistor, the first end of the second resistor is connected to the first node, and the first node is connected to the forward end of the error amplifier to output the reference signal; And a second switch controlled by the second dimming signal, the first end of the second switch is connected to the second end of the second resistor, and the second end of the second switch is connected to the negative end of the error amplifier .

如請求項3所述的發光二極體背光驅動裝置，其中該調整模組更包括：一第三開關，由該第一調光訊號控制，該第三開關之第一端連接該誤差放大器之輸出端，且該第三開關之第二端連接至該比較器之負向端。The illuminating diode backlight driving device of claim 3, wherein the adjusting module further comprises: a third switch controlled by the first dimming signal, wherein the first end of the third switch is connected to the error amplifier And an output end, and the second end of the third switch is connected to the negative end of the comparator.

如請求項4所述的發光二極體背光驅動裝置，其中該調整模組更包括：一運算放大器，該運算放大器之正向端接收該回授訊號，該運算放大器之負向端與該運算放大器之輸出端連接該第二開關之第二端。The illuminating diode backlight driving device of claim 4, wherein the adjusting module further comprises: an operational amplifier, the forward end of the operational amplifier receives the feedback signal, and the negative terminal of the operational amplifier and the operation The output of the amplifier is connected to the second end of the second switch.

如請求項2所述的發光二極體背光驅動裝置，其中該斜率補償器包括：一電流感測電路，接收該感測訊號，並根據該感測訊號輸出一感測電流；及一電流至電壓轉換電路，接收該感測電流，並根據該感測電流輸出該補償訊號。The illuminating diode backlight driving device of claim 2, wherein the slope compensator comprises: a current sensing circuit, receiving the sensing signal, and outputting a sensing current according to the sensing signal; and a current to The voltage conversion circuit receives the sensing current and outputs the compensation signal according to the sensing current.

如請求項2所述的發光二極體背光驅動裝置，其中該發光二極體電路包括：一電感，該電感之第一端連接至一電源電壓；一電晶體，該電晶體之控制端接收該控制訊號，該電晶體之第一端連接至該電感之第二端，且該電晶體之第二端連接至一第二節點，該第二節點連接至該斜率補償器以輸出該感測訊號；一第三電阻，該第三電阻之第一端連接至該第二節點，且該第三電阻之第二端接地；一第二電容，該第二電容之第一端接地，且該第二電容之第二端連接至該電感之第二端與該電晶體之第一端；一發光二極體，該發光二極體之第一端連接至該第二電容之第二端，且該發光二極體之第二端連接至一第三節點，該第三節點連接至該誤差放大器之負向端以輸出該回授訊號；及一第四電阻，該第四電阻之第一端接地，且該第四電阻之第二端連接至該第三節點。The illuminating diode backlight driving device of claim 2, wherein the illuminating diode circuit comprises: an inductor, the first end of the inductor is connected to a power supply voltage; and a transistor, the control terminal of the transistor receives The control signal, the first end of the transistor is connected to the second end of the inductor, and the second end of the transistor is connected to a second node, the second node is connected to the slope compensator to output the sensing a third resistor, the first end of the third resistor is connected to the second node, and the second end of the third resistor is grounded; a second capacitor, the first end of the second capacitor is grounded, and a second end of the second capacitor is connected to the second end of the inductor and the first end of the transistor; a light emitting diode, the first end of the light emitting diode is connected to the second end of the second capacitor, And the second end of the light emitting diode is connected to a third node, the third node is connected to the negative end of the error amplifier to output the feedback signal; and a fourth resistor, the first of the fourth resistor The terminal is grounded, and the second end of the fourth resistor is connected to the third section point.

如請求項7所述的發光二極體背光驅動裝置，其中該感測訊號為流過該第三電阻上之電流。The illuminating diode backlight driving device of claim 7, wherein the sensing signal is a current flowing through the third resistor.

如請求項7所述的發光二極體背光驅動裝置，其中該回授訊號為流經該發光二極體之電流於該第四電阻上形成之電壓。The illuminating diode backlight driving device of claim 7, wherein the feedback signal is a voltage formed on the fourth resistor by a current flowing through the illuminating diode.

如請求項7所述的發光二極體背光驅動裝置，其中該發光二極體電路更包含一二極體耦接於該電晶體之第一端與該第二電容之第二端間。The illuminating diode backlight driving device of claim 7, wherein the illuminating diode circuit further comprises a diode coupled between the first end of the transistor and the second end of the second capacitor.