201223317 γ 六、發明說明： 【發明所屬之技術領域】 本發明係關於一種回授控制電路及發光二極體驅動電 路，尤指一種可以提升發光二極體調光準確度之回授控制電路 及發光二極體驅動電路。 【先前技術】 近年來’由於發光二極體的使用壽命長、發光效率高、亮 度穩疋快速等特性’被視為下一個世代發光、照明的主要來源。 發光二極體可應用的照明領域相當廣，包括室内照明、室外照 鲁 明、廣告招牌…等。隨著發光二極體逐一取代現今的照明光 源’如何取得穩定光源的發光二極體並提供適當的保護，'使發 光二極體能發揮其特性之優點及提高使用上的安全已成為當 今重要的課題。 田 .請參見第一圖，為習知之發光二極體驅動電路之電路示意 圖。發光二極體驅動電路包含一回授控制電路100、一轉換電 路130及一發光二極體模組14〇。轉換電路13〇耦接一輸入電 壓源VIN’而回授控制電路1〇〇產生控制訊號Scl以控制轉換 電路130傳送來自輸入電壓源VIN至一輸出端的電力大小。 φ 轉換電路130的輸出端耦接發光二極體模組140，以施加一輸 出電壓VOUT至發光二極體模組140之上，使發光二極體模 組140流經一輸出電流I0UT而發光。輸出電流Ι〇υτ同時流 經一電流偵測電阻Ri以產生一電流回授訊號]；1^1。 回授控制電路100包含一脈寬控制單元U〇及一回授單元 120。回授單元120包含一放大單元122及一補償單元124 〇 放大單元122接收電流回授訊號ΐρΒ1及一參考訊號Vr，並據 此產生一輸出訊號並經補償單元124進行誤差補償後，成為一 脈寬控制訊號Veal。脈寬控制單元11〇包含一脈寬調變單元 112及一驅動單元114。其中，脈寬調變單元112接收脈寬控 制訊號Veal及一三角波訊號以據此產生一脈寬調變訊號S1 201223317 广 广 至驅動單元114，而驅動單元114則根據脈寬調變訊號si產 生控制訊號Scl。 一般而言’回授控制電路100會將輸出電流IOUT穩定在 一預疋輸出電流1〇 ’而此時輸出電塵VOUT也會穩定在一預 疋輸出電塵Vo。然而’放大單元122係經過比較電流回授訊 號IFB1及參考訊號Vr，並將兩訊號之誤差經補償單元124進 行誤差補償而調整脈寬控制訊號之準位。這樣的回授控制過程 會使輸出電流IOUT及輸出電壓VOUT會在預定輸出電流1〇 及預定輸出電壓Vo附近。 請參見第二圖，為第一圖所示發光二極體驅動電路於調光 過程的訊號波形圖。驅動單元114接收一調光訊號DIM並根 據調光訊號DIM決定是否輸出控制訊號Scl。在時間點T1_T4 之時間區間，調光訊號代表導通狀態，此時驅動單元114輸出 控制訊號Scl ;在時間點Τ4-Τ1之時間區間，調光訊號代表關 閉狀態，此時驅動單元114停止輸出控制訊號Sc】。在時間點 T4-T1之時間區間，因驅動單元114停止輸出控制訊號^丨使 轉換電路130停止傳送電力至發光二極體模組14〇，而使輸出 =VOUT於時間點T5時下降至發光二極體模组14〇的臨界 TPTM 輸出電流1〇说也降至零。這會造成電流回授訊號 〔士考訊號Vr維持正誤差’而使脈寬控制訊號顧之 1甚至上升至最大準位值。在理想的狀態下，時間點 β% w ^時間區間沒有功耗’使得輸出電壓V0UT維持在等於 3 實際上，發光二極體驅動電路會有漏電流之201223317 γ 6. Invention: [Technical Field] The present invention relates to a feedback control circuit and a light-emitting diode driving circuit, and more particularly to a feedback control circuit capable of improving the dimming accuracy of a light-emitting diode and Light-emitting diode drive circuit. [Prior Art] In recent years, due to the long service life of the light-emitting diode, high luminous efficiency, and stable brightness and fastness, it has been regarded as the main source of illumination and illumination for the next generation. Light-emitting diodes can be used in a wide range of lighting applications, including indoor lighting, outdoor lighting, advertising signs, and so on. As the light-emitting diodes replace the current illumination source one by one, how to obtain a light-emitting diode of a stable light source and provide appropriate protection, it is now important to enable the light-emitting diode to exert its characteristics and improve the safety of use. Question. Field. Please refer to the first figure, which is a circuit diagram of a conventional LED driving circuit. The LED driving circuit comprises a feedback control circuit 100, a conversion circuit 130 and a light emitting diode module 14A. The conversion circuit 13 is coupled to an input voltage source VIN' and the feedback control circuit 1 generates a control signal Scl to control the conversion circuit 130 to transfer the power from the input voltage source VIN to an output terminal. The output end of the φ conversion circuit 130 is coupled to the LED module 140 to apply an output voltage VOUT to the LED module 140, so that the LED module 140 flows through an output current IOUT. . The output current Ι〇υτ flows through a current detecting resistor Ri to generate a current feedback signal]; 1^1. The feedback control circuit 100 includes a pulse width control unit U and a feedback unit 120. The feedback unit 120 includes an amplifying unit 122 and a compensating unit 124. The amplifying unit 122 receives the current feedback signal ΐρΒ1 and a reference signal Vr, and generates an output signal according to the error compensation unit 124 to obtain a pulse. Wide control signal Veal. The pulse width control unit 11A includes a pulse width modulation unit 112 and a driving unit 114. The pulse width modulation unit 112 receives the pulse width control signal Veal and a triangular wave signal to generate a pulse width modulation signal S1 201223317 to the driving unit 114, and the driving unit 114 generates the signal according to the pulse width modulation signal si. Control signal Scl. In general, the feedback control circuit 100 stabilizes the output current IOUT at a pre-output current 1 〇 ′ while the output dust VOUT is also stabilized at a pre-output electric dust Vo. However, the amplifying unit 122 compares the current feedback signal IFB1 and the reference signal Vr, and compensates the error of the two signals by the compensation unit 124 to adjust the level of the pulse width control signal. Such a feedback control process causes the output current IOUT and the output voltage VOUT to be near a predetermined output current 1 〇 and a predetermined output voltage Vo. Please refer to the second figure, which is the signal waveform diagram of the dimming driving circuit shown in the first figure during the dimming process. The driving unit 114 receives a dimming signal DIM and determines whether to output the control signal Scl according to the dimming signal DIM. In the time interval of the time point T1_T4, the dimming signal represents the conduction state, at which time the driving unit 114 outputs the control signal Scl; in the time interval of the time point Τ4-Τ1, the dimming signal represents the off state, at which time the driving unit 114 stops the output control. Signal Sc]. In the time interval of the time point T4-T1, the driving unit 114 stops outputting the control signal, so that the conversion circuit 130 stops transmitting power to the LED module 14A, and causes the output=VOUT to drop to the light at the time point T5. The critical TPTM output current of the diode module 14〇 is also reduced to zero. This causes the current feedback signal (the test signal Vr maintains a positive error) and the pulse width control signal even rises to the maximum level. In the ideal state, the time point β% w ^ time interval has no power consumption', so that the output voltage VOUT is maintained equal to 3. In fact, the LED driving circuit has leakage current.
2門電壓V〇UT之下降，使得輸出電壓V〇UT 時間區間仍持續下降至低於臨界電壓对。 於二驅動單疋114重新輸出控制訊號Scl時，由 3 U之準位在最大值，使控制訊號SC1的工 作週期[Duty Cycle)也在最大值。 接著於時間點T2之後，輸出電流 電流^做大料122 _舰_赚^預之^ ，·'·ϋ r Μ ιώ Ί.2ί·. 201223317 然而，由於補償單元124的誤差補償關係，脈寬控制訊號Veal 無法直接下降至一誤差穩定值Vealo (此值為輸出電流ιουτ 穩定預定輸出電流1〇時對應的脈寬控制訊號Veal的準位）。 這導致此時的控制訊號Scl的工作週期過大，使輸出電流 ιουτ仍繼續上升直至脈寬控制訊號Veai低於誤差穩定值 Vealo。於後’輸出電流I0UT再度低於預定輸出電流&，使 脈寬控制訊號Veal重新上升並超過誤差穩定值Veal〇。上述 過私將持續直至時間點T3，輸出電流IOUT、輸出電壓v〇UT、 脈寬控制訊號Veal分別收斂至對應的預定輸出電流1〇、預定 輸出電壓V6及誤差穩定值Veal0為止。 因此，當調光訊號代表為第二狀態時，發光二極體驅動電 路之漏電流會使得輸出電壓V0UT下降至低於臨界電壓 Vf，使當調光訊號代表為第一狀態時，發光二極體驅動電路 需較長的時間才能達到穩定，而這會影響調光的準確度。 【發明内容】 鑑於先前技術中’發光二極體驅動電路於調光過程會有調 光不精確之問題，本發明利用於調光訊號代表關閉時，仍控制 轉換電路維持極小的電力轉換，以維持輸出電壓維持在發光二 極體模組的臨界電壓附近。本發明也可以進一步將輸出電壓、 控制轉換電路轉換電力的控制訊號維持在穩定操作的值附 近’使下一個週期的操作可直接穩定操作。 為達上述目的，本發明提供了一種回授控制電路，用以控 制一轉換電路將一電源之電力轉換以驅動一發光二極體模 組。回授控制電路包含一回授單元及一脈寬控制單元。回授單 元接收代表發光二極體模組的狀態之一回授訊號，以據此產生 一脈寬控制訊號；脈寬控制單元則根據脈寬控制訊號以產生至 匕:控制訊號以控制轉換電路進行電力轉換。其中，脈寬控制 單元包含一調光控制單元及一驅動單元。調光控制單元根據一 調光訊號及一調光關閉控制單元所產生的一脈衝訊號以產生The drop of the 2-gate voltage V〇UT causes the output voltage V〇UT time interval to continue to drop below the threshold voltage pair. When the second driving unit 114 re-outputs the control signal Scl, the level of 3 U is at the maximum value, so that the duty cycle [Duty Cycle) of the control signal SC1 is also at the maximum value. Then, after the time point T2, the output current current ^ is made of the bulk material 122 _ ship_ earning ^previous ^,·'·ϋ r Μ ιώ Ί.2ί·. 201223317 However, due to the error compensation relationship of the compensation unit 124, the pulse width The control signal Veal cannot be directly lowered to an error stable value Vealo (this value is the level of the corresponding pulse width control signal Veal when the output current ιουτ stabilizes the predetermined output current 1〇). This causes the duty cycle of the control signal Scl at this time to be too large, so that the output current ιουτ continues to rise until the pulse width control signal Veai is lower than the error stable value Vealo. After that, the output current IOUT is again lower than the predetermined output current & the pulse width control signal Veal rises again and exceeds the error stable value Veal〇. The above-mentioned over-privacy will continue until the time point T3, and the output current IOUT, the output voltage v〇UT, and the pulse width control signal Veal respectively converge to the corresponding predetermined output current 1〇, the predetermined output voltage V6, and the error stable value Veal0. Therefore, when the dimming signal is represented as the second state, the leakage current of the LED driving circuit causes the output voltage VOUT to fall below the threshold voltage Vf, so that when the dimming signal represents the first state, the light emitting diode The body drive circuit takes a long time to stabilize, which affects the accuracy of dimming. SUMMARY OF THE INVENTION In view of the prior art 'light-emitting diode driving circuit has dimming inaccuracy in the dimming process, the present invention is used to control the switching circuit to maintain a minimum power conversion when the dimming signal represents off. The output voltage is maintained to be maintained near the threshold voltage of the LED module. The present invention can further maintain the output voltage and the control signal for controlling the conversion circuit to convert power to be near the value of the stable operation, so that the operation of the next cycle can be directly stabilized. To achieve the above object, the present invention provides a feedback control circuit for controlling a conversion circuit to convert the power of a power source to drive a light emitting diode module. The feedback control circuit includes a feedback unit and a pulse width control unit. The feedback unit receives a feedback signal representing a state of the LED module to generate a pulse width control signal according to the pulse width control unit to generate a control signal according to the pulse width control signal to control the conversion circuit. Perform power conversion. The pulse width control unit includes a dimming control unit and a driving unit. The dimming control unit generates a pulse signal generated by the control unit according to a dimming signal and a dimming control unit to generate
201223317 「 r 一調光控制訊號；驅動單元根據脈寬控制訊號以及調光控制訊 號，以據此產生至少一控制訊號。其中，調光訊號於一第一狀 態以及一第二狀態之間切換，調光訊號於第一狀態時，回授控 制電路控制轉換電路以驅動發光二極體模組穩定發光；調光訊 號於第二狀態時，回授控制電路控制轉換電路以維持轉換電路 進行電力轉換，使得轉換電路所產生的一輸出電壓維持在發光 二極體模組之一臨界電壓附近。 本發明也提供了一種發光二極體驅動電路，用以驅動一發 光二極體模組’發光二極體模組具有複數個發光二極體串且發 光二極體串彼此並聯。發光二極體驅動電路包含一電流平衡模 組、一極端電壓偵測電路、一轉換電路以及一回授控制電路。 電流平衡模組具有複數個電流平衡端對應耦接複數個發光二 極體串，用以平衡複數個發光二極體串之電流。極端電壓偵測 電路耦接複數個電流平衡端’並根據複數個電流平衡端的電位 產生一回授訊號。轉換電路耦接發光二極體模組，用以將一輸 入電壓之電力轉換成一輸出電壓以驅動發光二極體模組。回授 控制電路用以控制轉換電路進行電壓轉換，回授控制電路接收 一調光訊號，並根據調光訊號操作於一第一狀態或一第二狀 態。其中，回授控制電路操作於第一狀態時，轉換電路之電力 轉換之平均值大於回授控制電路操作於第二狀態時轉換電路 之電力轉換之平均值且均大於零。 以上的概述與接下來的詳細說明皆為示範性質，是為了進 一步說明本發明的申請專利範圍。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】 一一請參見第三圖，為根據本發明之一第一較佳實施例之一發 光了極體驅動電路之電路示意圖。發光二極體驅動電路包含一 回授控制電路200以及一轉換電路230，用以驅動一發光二極 201223317 「 Γ 體模組240»回授控制電路200接收一電流回授訊號IFB2，以 據此進行回授控制以產生一控制訊號Sc2以控制轉換電路 230。轉換電路230之輸入端耦接一輸入電壓源VIN，輸出端 耦接發光二極體模組240，以根據控制訊號Sc2來調控輸入電 壓源VIN之電力大小，並轉換成適當的一輸出電壓νουτ以 驅動發光二極體模組240，使流經發光二極體模組24〇的一輸 出電流ιουτ穩定於一預定輸出電流值。而輸出電流ιουτ同 時也流過一電流偵測電阻Ri’以產生代表輸出電流Ι〇υτ大小 的電流回授訊號IFB2〇 回授控制電路200包含一回授單元22〇以及一脈寬控制單 元210。回授單元220包含一放大單元222、一補償單元224 以及一回授開關226。放大單元222之非反相輸入端接收一第 一參考訊號Vrl ’反相輸入端接收電流回授訊號jpB2，以據此 產生一誤差訊號。補償單元224根據誤差訊號產生一脈寬控制 訊说Vea2。補償單元224 —般包含電容及電阻，根據實際應 用的電路調整補償單元224的電壓增益對頻率的變化關係，使 回授控制電路200的回授控制有較佳的暫態反應。回授開關 226耦接於放大單元222及補償單元224之間，用以根據一調 光訊號DIM控制誤差訊號傳送至補償單元224。當調光訊號 DIM的狀態為代表ON’的一第一狀態時，回授開關226導 通’放大單元222所產生的誤差訊號透過回授開關226傳送至 補償單元224;而當調光訊號DIM的狀態為代表，，0FF”的一 第二狀態時，回授開關226截止，放大單元222所產生的誤差 訊號停止傳送至補償單元224。 ' 脈寬控制單元210根據脈寬控制訊號Vea2以產生一控制 訊號Sc2以據此控制轉換電路230進行電壓轉換。脈寬控制單 元210包含一脈寬調變單元212、一調光控制單元216及一驅 動單元214。脈寬調變單元212可為一比較器，其非反相輸入 端接收脈寬控制訊號Vea2以及反相輸入端接收一主角波訊 號，以據此產生一脈寬調變訊號S2至驅動單元214。調光控 201223317 r 制單元216包含一或閘218接收一調光訊號DIM及一調光關 閉控制單元217所產生之脈衝訊號，以據此產生一調光控制訊 號P2。其中’調光關閉控制單元217所產生之週期訊號可為 一固定脈寬訊號。接著，驅動單元214同時接收脈寬調變訊號 S2以及調光控制訊號P2,當調光訊號DM為一第一狀態時， 驅動單元214根據脈寬調變訊號S2產生控制訊號Sc2 ;當調 光訊號DIM為一第二狀態時，驅動單元214則根據調光控制 單元216所產生的調光控制訊號p2產生控制訊號Sc2。如此， 調光訊號SIM為第一狀態時，回授控制電路2〇〇控制轉換電 路230以驅動發光二極體模組240穩定發光；調光訊號DIM 為第二狀態時，回授控制電路200控制轉換電路230以維持轉 換電路230進行電力轉換，使得轉換電路230所產生的一輸出 電壓VOUT維持在發光二極體模組240之一臨界電壓附近。 再來，請參見第四圖，為第三圖所示之發光二極體驅動電 路於調光過程的訊號波形圖。請同時參見第三圖，於時間點 tl，調光訊號DIM由第二狀態的低準位轉為第一狀態的高準 位。此時’輸出電壓VOUT由臨界電壓Vf附近上升，輸出電 流IOUT從零準位開始上升。此時，回授開關226導通，因此， 控制訊號Sc2的工作週期由一預定工作週期開始進行回授控 制。於時間點t2，輸出電流IOUT到達預定輸出電流ι〇，此時 脈寬控制訊號Vea2到達一峰值。而由於脈寬控制訊號Vea2係 由一預定工作週期開始上升，而預定工作週期為等於或低於一 誤差穩定值Vea2o(此值為輸出電流ιουτ穩定至預定輸出電流 1〇時對應的脈寬控制訊號Vea2的準位)+’而非如先前技術般由 脈寬控制訊號Vea2的最大值開始，故此峰值不易到達脈寬控 制訊號Vea2的最大值。 " 因此，輸出電壓VOUT、輸出電流ιουτ及脈寬控制訊號 Vea2相較於先前技術更快達到穩定。於時間點t3，調光訊號 DIM由第一狀態的高準位轉為第二狀態的低準位。輸出電壓 VOUT及輸出電流IOUT開始下降，直至輸出電流ιουτ為零 201223317 r 广 為止。此時，控制訊號Sc2的工作週期為一脈衝訊號，用以提 供-極小的電力至轉換電路230之輸出端而補償電路上的一 些漏流等電力損耗’如此可將輸出電壓ν〇υτ維持在臨界 壓Vf附近。因此’於脈衝訊破產生時，輪出電壓v〇uT上升， 使得輸出電壓VOUT在臨界電壓Vf附近。 本發明之發光二極體驅動電路内的轉換電路，可利用具有 直流電壓輸之轉換電路，例如：錢轉直流升/降壓電 路、反馳式轉換電路、順向式轉換電路等。以下以順向式轉換 電路說明。 ' 請參見第五圖’為根據本發明之一第二較佳實施例之發光 • 二極體驅動電路之電路示意圖。相較於第三圖所示之第一較佳 實施例’在本實施例中的發光二極體驅動電路額外增加一驅動 開關350耦接發光二極體模組340，以根據調光訊號DIM控 制轉換電路是否提供電力至發光二極體模組34(^發光二極體 驅動電路包含一回授控制電路3〇〇以及一轉換電路33〇，用以 驅動一發光二極體模組340。轉換電路330透過一橋式整流器 BD耦接一交流輸入電源VAC，以根據一控制訊妩Sc3將交流 輸入電源VAC做一電力轉換，以驅動發光二極體模組34〇發 光。在本實施中，轉換電路330為一順向式轉換電路，包含一 • 變壓器T、一電晶體開關SW、整流二極體D1、D2、電感L 以及一輸出電容〇變壓器T之初級側之一端耦接交流輸入電 源VAC ’另一端耦接電晶體開關sw之一端，而電晶體開關 SW之另一端透過一電流偵測電阻接地，以產生一電流回授訊 號1FB3。輸出電容C透過整流二極體！m、D2及電感l耦接 變壓器T之次級側。一電壓偵測電路332耦接電容c以產生 代表輸出電壓VOUT大小的電壓回授訊號VFB3。為了確保發 光二極體模組340穩定發光，發光二極體模組340耦接一電流 源1s ’使得輸出電流IOUT穩定於一預定輸出電流值。 控制電路300包含一回授單元320以及一脈寬控制單元 310。回授單元320包含一比較器322及一訊號疊加單元324， 201223317 Γ r 訊號疊加單元324接收電流回授訊號IFB3及電壓回授訊號 VFB3以產生一回授訊號FB3。比較器322之反相輸入端接收 一第二參考訊號Vr2，非反相輸入端接收回授訊號FB3，以據 此產生脈寬控制訊號Vea3。脈寬控制單元310包含一 SR正反 器312、一調光控制單元316以及一驅動單元314。SR正反器 312之設定端S接收一時脈訊號PU ’而重設端R接收脈寬控 制訊號Vea3。當SR正反器312於設定端S接收到時脈訊號 PU時’由輸出端Q產生一脈寬調變訊號S3至驅動電路314。 調光控制單元316包含一調光關閉控制單元317、一或閘 318以及一調光器319。調光器319接收一直流調光訊號DC 及一三角波，以產生調光訊號DIM。調光關閉控制單元317 # 為一比較器，其反相輸入端接收一電壓回授訊號VFB3，非反 相輸入端接收一第三參考電壓Vr3 ’使得電壓回授訊號VFB3 低於第三參考電壓Vr3時，調光關閉控制單元317會產生一脈 衝訊號。或閘318接收調光訊號DIM及調光關閉控制單元317 所產生之脈衝訊號’以據此產生一調光控制訊號P3。相較於 第一較佳實施例’調光關閉控制單元317產生的脈衝訊號雖為 不固定週期，然亦可達到相同的效果。 接者’驅動單元314同時接收脈寬調變訊號S3以及調光 控制訊號P3，當調光訊號DIM為代表” on”之一第一狀態， 此時’驅動單元314根據脈寬調變訊號S3產生控制訊號Sc2 ; 當調光訊號DIM為代表” OFF”之一第二狀態，驅動單元314 則根據調光控制訊號P3產生控制訊號Sc3。如此，當調光訊 號DIM為第二狀態時’驅動開關350截止使電容c所儲存的 電力不至因發光二極體模組340而下降；且轉換電路33〇仍可 挺供一極小電力至電容C以補償因漏流等所造成的電力損耗。 在本實施例’轉換電路330為順向式轉換電路，而實際應 用上也可以是反馳式轉換電路、半橋式轉換電路或全橋式轉換 電路等，控制電路300則需對應轉換電路的不同產生一個或以 上控制訊號來正確地控制轉換電路運作。此為此領域者所熟 ν·· ·*·. .....,........... ί ||ϋ|ΐΊ| - 201223317 知’在此不再累述。 再來，請參見第七圖，為根據第五圖所示的發光二極體驅 動電路於調光過程的訊號波形圖。請同時參見第五圖，於時間 點tl，調光訊號DIM由第二狀態的低準位轉為第一狀態的高 準位，驅動開關350導通。輸出電壓VOUT由一預定值開始 本升，輸出電流IOUT則從零準位快速上升。SR正反器31^ 被脈衝訊號PU觸發而產生高準位訊號，因此控制訊號Sc3亦 為高^位。電流回授訊號IFB3從零準位開始上升，使得訊號 疊加單元324之準位亦持續上升，此時脈寬控制訊號Vea3為 低準位。於時間點t2，訊號疊加單元324之準位到達一第二參 考電壓Vr2 ’使得脈寬控制訊號Vea3轉為高準位，SR正反器 被重设而輸出低準位訊號’使得控制訊號Sc3亦轉為低準位。 下二個週期，脈衝訊號PU再度觸發SR正反器312產生高準 位訊號而重覆時間點tl-t2之時間區間的步驟，使得輸出電壓 VOUT及輸出電流IOUT穩定於一預定輸出電壓v〇及一預定 輸出電流1〇。於時間點t3時，調光訊號DIM由第一狀態的高 位準轉為第二狀態的低位準。此時，驅動開關35〇導通截止， 輸出電壓VOUT仍維持在預定輸出電壓ν〇附近而輸出電流 IOUT立即降為零。在t3-tl時間區間内，當輸出電壓νουτ 降至一預定值，使電壓回授訊號WB3低於一第三餐考電壓 時，調光控制訊號P3轉為高準位，以輸出控制訊號Sc3。如 此輸出電壓VOUT再度上升至高於此預定值。也就是說，輸 出電壓VOUT將被維持在此預定值附近，以補償電路漏流的 功，耗耗。因此，當調光訊號DIM再度由第二狀態的低準位 轉為第一狀態的高準位，輸出電壓νουτ由預定值開始上升’ 可更快速到達穩疋狀態，提升調光的準確度。 請參見第六圖，為根據本發明之一第三較佳實施例之一發 光一極體驅動電路之電路示意圖^發光二極體驅動電路包含一 回授控制電路400以及一轉換電路43〇，用以驅動一發光二極 體模組440。回授控制電路4〇〇接收一回授訊號FB4 ,以據此 201223317 進行回授控制以產生一控制訊號Sc4以控制轉 換電路430之輸入端耦接一輸入電壓源爾出 二極體模組440。相較於第三圖所示之實施例， 光-極體模組440具有複數個發光二極體串且這些 體串彼此並聯。此外’為了確保發光二極體模纟且“ ^一 發光2體均致相關電流，發光二極體驅動電路可辦 加-電平衡單S460，具有複數個電流平衡端m〜D ^ 耦接發光二極麵組440中的複數個發光二極體串，以衡^ 數個發光二極體φ之電流，使每枝光二極財之電流穩 -預定輸出電流值’而複數個驅動開關45G對應輕接於g二 極體模組440以及電流平衡單元46〇之間。由於每串發光二& 體串流經預定輸出電流值所需之驅動電壓並不相同 個電流平衡端D1〜Dn的f壓高低不同。為使賴平衡 =的電流平衡端D1〜Dn均可正常操作，即可控制流經的電 k為預定$出電流值’電流平衡端D1〜Dn的準位必須維持在 一最低可操作電壓值。為此，本發明可增加一極端電壓偵測 路470，輕接複數個電流平衡端m〜Dn，並根據電流平衡端 D1〜Dn之間最低電位產生一回授訊號FB4。極端電壓偵測電 路470可包含複數個二極體，其負端分別_搞接至複數個電 流平衡端D1〜Dn，而其正端彼此連接並透過一電阻耦接至一 驅?電源VCC。如此，除具*最低電位之電解衡端所對應 的二極體可順向導通外’其餘二極體原則上因跨壓不足而無法 導通，使回授訊號FB4的電位為電流平衡端的最低電位加上 一極體的順向偏壓。接著，回授控制之電路運作方式與本 發明第三圖所示之電路大致相同，在此不予贅述。 、 如上所述，本發明完全符合專利三要件：新穎性、進步性 和產業上的利用性。本發明在上文中已以較佳實施例揭露，然 熟習本項技術者應理解的是，該實施例僅用於描繪本發明，而 不應解讀為限制本發明之範圍。應注意的是，舉凡與該實施例 等效之變化與置換，均應設為涵蓋於本發明之範疇内。因此， 12 201223317 「 本發明之保護範圍當以下文之申請專利範圍所界定者為準。201223317 ” r a dimming control signal; the driving unit generates at least one control signal according to the pulse width control signal and the dimming control signal, wherein the dimming signal switches between a first state and a second state, When the dimming signal is in the first state, the feedback control circuit controls the conversion circuit to drive the LED module to stably emit light; when the dimming signal is in the second state, the feedback control circuit controls the conversion circuit to maintain the conversion circuit for power conversion. The output voltage generated by the conversion circuit is maintained near a threshold voltage of the LED module. The invention also provides a LED driving circuit for driving a LED module 'Lighting II The polar body module has a plurality of light emitting diode strings and the light emitting diode strings are connected in parallel with each other. The light emitting diode driving circuit comprises a current balancing module, an extreme voltage detecting circuit, a converting circuit and a feedback control circuit. The current balancing module has a plurality of current balancing ends correspondingly coupled to the plurality of LED strings for balancing a plurality of LEDs The current of the string is coupled to the plurality of current balancing terminals and generates a feedback signal according to the potentials of the plurality of current balancing terminals. The conversion circuit is coupled to the LED module for powering an input voltage. Converting into an output voltage to drive the LED module. The feedback control circuit is configured to control the conversion circuit for voltage conversion, and the feedback control circuit receives a dimming signal and operates in a first state or a first according to the dimming signal. The second state, wherein the feedback control circuit operates in the first state, the average value of the power conversion of the conversion circuit is greater than the average value of the power conversion of the conversion circuit when the feedback control circuit operates in the second state, and both are greater than zero. The detailed description and the following detailed description are intended to be illustrative of the scope of the invention. Referring to the third figure, a circuit diagram of a polar body driving circuit is illuminated according to a first preferred embodiment of the present invention. The LED driving circuit includes a feedback control circuit 200 and a conversion circuit 230 for driving a light-emitting diode 201223317 "the body module 240" feedback control circuit 200 receives a current feedback signal IFB2 to The feedback control is performed to generate a control signal Sc2 to control the conversion circuit 230. The input end of the conversion circuit 230 is coupled to an input voltage source VIN, and the output end is coupled to the LED module 240 to be based on the control signal Sc2. Regulating the power of the input voltage source VIN and converting it to an appropriate output voltage νουτ to drive the LED module 240 to stabilize an output current ιουτ flowing through the LED module 24〇 to a predetermined output current The output current ιουτ also flows through a current detecting resistor Ri' to generate a current feedback signal IFB2 representing the magnitude of the output current Ι〇υτ. The feedback control circuit 200 includes a feedback unit 22〇 and a pulse width control. Unit 210. The feedback unit 220 includes an amplifying unit 222, a compensation unit 224, and a feedback switch 226. The non-inverting input of the amplifying unit 222 receives a first reference signal Vrl', and the inverting input receives the current feedback signal jpB2 to generate an error signal accordingly. The compensation unit 224 generates a pulse width control message Vea2 based on the error signal. The compensation unit 224 generally includes a capacitor and a resistor, and adjusts the relationship between the voltage gain of the compensation unit 224 and the frequency according to the circuit of the actual application, so that the feedback control of the feedback control circuit 200 has a better transient response. The feedback switch 226 is coupled between the amplifying unit 222 and the compensating unit 224 for transmitting the error signal to the compensating unit 224 according to a dimming signal DIM. When the state of the dimming signal DIM is a first state representing ON', the error signal generated by the feedback switch 226 turning on the 'amplifying unit 222 is transmitted to the compensation unit 224 through the feedback switch 226; and when the dimming signal DIM is When the state is a representative, in a second state of 0FF", the feedback switch 226 is turned off, and the error signal generated by the amplifying unit 222 is stopped from being transmitted to the compensation unit 224. The pulse width control unit 210 generates a signal according to the pulse width control signal Vea2. The control signal Sc2 controls the conversion circuit 230 to perform voltage conversion. The pulse width control unit 210 includes a pulse width modulation unit 212, a dimming control unit 216, and a driving unit 214. The pulse width modulation unit 212 can be a comparison. The non-inverting input terminal receives the pulse width control signal Vea2 and the inverting input terminal receives a lead wave signal to generate a pulse width modulation signal S2 to the driving unit 214. The dimming control 201223317 r unit 216 includes A thyristor 218 receives a dimming signal DIM and a dimming signal from the dimming off control unit 217 to generate a dimming control signal P2. The dimming off control unit 217 The generated periodic signal can be a fixed pulse width signal. Then, the driving unit 214 receives the pulse width modulation signal S2 and the dimming control signal P2 at the same time. When the dimming signal DM is in a first state, the driving unit 214 is based on the pulse. The wide adjustment signal S2 generates the control signal Sc2. When the dimming signal DIM is in the second state, the driving unit 214 generates the control signal Sc2 according to the dimming control signal p2 generated by the dimming control unit 216. Thus, the dimming signal When the SIM is in the first state, the feedback control circuit 2 〇〇 controls the conversion circuit 230 to drive the LED module 240 to stably emit light; when the dimming signal DIM is in the second state, the feedback control circuit 200 controls the conversion circuit 230 to The conversion circuit 230 is maintained to perform power conversion such that an output voltage VOUT generated by the conversion circuit 230 is maintained near a threshold voltage of the LED module 240. Referring to the fourth figure, the third figure is shown in FIG. The signal waveform of the dimming diode driving circuit during the dimming process. Please also refer to the third figure. At time t1, the dimming signal DIM is changed from the low level of the second state to the first state of Micro Motion. At this time, the output voltage VOUT rises from the vicinity of the threshold voltage Vf, and the output current IOUT rises from the zero level. At this time, the feedback switch 226 is turned on, and therefore, the duty cycle of the control signal Sc2 is started from a predetermined duty cycle. Controlling. At time t2, the output current IOUT reaches a predetermined output current ι〇, at which time the pulse width control signal Vea2 reaches a peak value, and since the pulse width control signal Vea2 starts to rise by a predetermined duty cycle, the predetermined duty cycle is Is equal to or lower than an error stable value Vea2o (this value is the level of the corresponding pulse width control signal Vea2 when the output current ιουτ is stabilized to the predetermined output current 1〇) +' instead of the pulse width control signal Vea2 as in the prior art The maximum value starts, so the peak value does not easily reach the maximum value of the pulse width control signal Vea2. " Therefore, the output voltage VOUT, the output current ιουτ, and the pulse width control signal Vea2 are stabilized faster than the prior art. At time t3, the dimming signal DIM is changed from the high level of the first state to the low level of the second state. The output voltage VOUT and the output current IOUT begin to decrease until the output current ιουτ is zero 201223317 r wide. At this time, the duty cycle of the control signal Sc2 is a pulse signal for providing - very small power to the output of the conversion circuit 230 to compensate for some leakage current and other power losses on the circuit. Thus, the output voltage ν 〇υ τ can be maintained at Near the critical pressure Vf. Therefore, when the pulse burst occurs, the turn-on voltage v〇uT rises so that the output voltage VOUT is near the threshold voltage Vf. The conversion circuit in the LED driving circuit of the present invention can utilize a conversion circuit having a DC voltage input, such as a money-to-DC rise/down circuit, a flyback conversion circuit, a forward conversion circuit, or the like. The following is a description of the forward conversion circuit. 'See Fig. 5' is a circuit diagram of a light-emitting diode driving circuit according to a second preferred embodiment of the present invention. Compared with the first preferred embodiment shown in the third figure, the LED driver circuit in the embodiment further adds a driving switch 350 coupled to the LED module 340 to be based on the dimming signal DIM. The control conversion circuit provides power to the LED module 34. The LED driver circuit includes a feedback control circuit 3A and a conversion circuit 33A for driving a LED module 340. The conversion circuit 330 is coupled to an AC input power source VAC via a bridge rectifier BD to perform a power conversion of the AC input power source VAC according to a control signal Sc3 to drive the LED module 34 to emit light. In this implementation, The conversion circuit 330 is a forward conversion circuit comprising a transformer T, a transistor switch SW, a rectifying diode D1, D2, an inductor L, and an output capacitor. One of the primary sides of the transformer T is coupled to the AC input power source. The other end of the VAC 'couples to one end of the transistor switch sw, and the other end of the transistor switch SW is grounded through a current detecting resistor to generate a current feedback signal 1FB3. The output capacitor C passes through the rectifying diode m, D2 and the inductor 1 are coupled to the secondary side of the transformer T. A voltage detecting circuit 332 is coupled to the capacitor c to generate a voltage feedback signal VFB3 representing the magnitude of the output voltage VOUT. To ensure stable illumination of the LED module 340 The light-emitting diode module 340 is coupled to a current source 1s′ to stabilize the output current IOUT to a predetermined output current value. The control circuit 300 includes a feedback unit 320 and a pulse width control unit 310. The feedback unit 320 includes a The comparator 322 and the signal superimposing unit 324, 201223317 Γ r signal superimposing unit 324 receives the current feedback signal IFB3 and the voltage feedback signal VFB3 to generate a feedback signal FB3. The inverting input of the comparator 322 receives a second reference. The signal Vr2 receives the feedback signal FB3 from the non-inverting input terminal to generate the pulse width control signal Vea3. The pulse width control unit 310 includes an SR flip-flop 312, a dimming control unit 316 and a driving unit 314. The set terminal S of the flip-flop 312 receives a clock signal PU' and the reset terminal R receives the pulse width control signal Vea3. When the SR flip-flop 312 receives the clock signal PU at the set terminal S, it is generated by the output terminal Q. The pulse width modulation signal S3 is connected to the driving circuit 314. The dimming control unit 316 includes a dimming off control unit 317, a gate 318, and a dimmer 319. The dimmer 319 receives the DC dimming signal DC and a triangular wave. To generate the dimming signal DIM. The dimming off control unit 317 # is a comparator whose inverting input receives a voltage feedback signal VFB3, and the non-inverting input receives a third reference voltage Vr3 'so that the voltage is fed back When the signal VFB3 is lower than the third reference voltage Vr3, the dimming off control unit 317 generates a pulse signal. The OR gate 318 receives the pulse signal DIM generated by the dimming signal DIM and the dimming off control unit 317 to generate a dimming control signal P3 accordingly. Compared with the pulse signal generated by the dimming off control unit 317 of the first preferred embodiment, although the pulse signal is not fixed, the same effect can be achieved. The driver unit 314 receives the pulse width modulation signal S3 and the dimming control signal P3 at the same time. When the dimming signal DIM is in a first state representing "on", the driving unit 314 adjusts the signal according to the pulse width modulation signal S3. The control signal Sc2 is generated. When the dimming signal DIM is in a second state representing "OFF", the driving unit 314 generates the control signal Sc3 according to the dimming control signal P3. Thus, when the dimming signal DIM is in the second state, the driving switch 350 is turned off so that the power stored in the capacitor c is not lowered by the LED module 340; and the switching circuit 33 can still supply a very small power to Capacitor C compensates for power loss due to leakage current or the like. In the embodiment, the conversion circuit 330 is a forward conversion circuit, and the actual application may also be a reverse conversion conversion circuit, a half bridge conversion circuit or a full bridge conversion circuit, etc., and the control circuit 300 needs to correspond to the conversion circuit. Different one or more control signals are generated to properly control the operation of the conversion circuit. This is familiar to the field ν·····. .....,........... ί ||ϋ|ΐΊ| - 201223317 Known' is no longer described here. Next, please refer to the seventh figure, which is a signal waveform diagram of the dimming process according to the LED driving circuit shown in FIG. Please also refer to the fifth figure. At time t1, the dimming signal DIM is changed from the low level of the second state to the high level of the first state, and the driving switch 350 is turned on. The output voltage VOUT starts from a predetermined value, and the output current IOUT rises rapidly from the zero level. The SR flip-flop 31^ is triggered by the pulse signal PU to generate a high-level signal, so the control signal Sc3 is also high. The current feedback signal IFB3 rises from the zero level, so that the level of the signal superimposing unit 324 also continues to rise, and the pulse width control signal Vea3 is at a low level. At time t2, the level of the signal superimposing unit 324 reaches a second reference voltage Vr2' such that the pulse width control signal Vea3 is turned to a high level, and the SR flip-flop is reset to output a low level signal 'to make the control signal Sc3 Also turned to low level. In the next two cycles, the pulse signal PU triggers the step of the SR flip-flop 312 to generate the high-level signal and repeats the time interval of the time point t1-t2, so that the output voltage VOUT and the output current IOUT are stabilized at a predetermined output voltage v〇. And a predetermined output current of 1 〇. At time t3, the dimming signal DIM is changed from the high level of the first state to the low level of the second state. At this time, the drive switch 35 is turned on and off, the output voltage VOUT is maintained near the predetermined output voltage ν 而 and the output current IOUT is immediately reduced to zero. During the t3-tl time interval, when the output voltage νουτ falls to a predetermined value and the voltage feedback signal WB3 is lower than a third test voltage, the dimming control signal P3 is turned to a high level to output the control signal Sc3. . Thus, the output voltage VOUT rises again above this predetermined value. That is to say, the output voltage VOUT will be maintained near this predetermined value to compensate for the work and leakage of the circuit leakage. Therefore, when the dimming signal DIM is again changed from the low level of the second state to the high level of the first state, the output voltage νουτ starts to rise from the predetermined value, and the steady state can be reached more quickly, and the accuracy of the dimming is improved. 6 is a circuit diagram of a light-emitting one-pole driving circuit according to a third preferred embodiment of the present invention. The light-emitting diode driving circuit includes a feedback control circuit 400 and a conversion circuit 43A. It is used to drive a light emitting diode module 440. The feedback control circuit 4 receives a feedback signal FB4, and performs feedback control according to the 201223317 to generate a control signal Sc4 to control the input end of the conversion circuit 430 to be coupled to an input voltage source and output diode module 440. . In contrast to the embodiment shown in the third figure, the photo-polar body module 440 has a plurality of light-emitting diode strings and these body strings are connected in parallel with each other. In addition, in order to ensure that the light-emitting diodes are molded and "a light-emitting body is related to the current, the light-emitting diode driving circuit can be operated with an electric-balanced single S460, and has a plurality of current-balanced ends m~D^ coupled with light. The plurality of light-emitting diode strings in the dipole face group 440 balance the current of each of the light-emitting diodes φ to a predetermined output current value of the plurality of light-emitting diodes φ and the plurality of drive switches 45G correspond to Lightly connected between the g diode module 440 and the current balancing unit 46. Since the driving voltage required to flow the predetermined output current value per string of the lighted & string is not the same as the current balancing terminals D1 to Dn f. The voltage level is different. In order to make the current balance terminals D1~Dn of the balance = normal operation, the electric current flowing through can be controlled to be a predetermined value of the current value. The level of the current balance terminals D1 to Dn must be maintained at one level. The minimum operable voltage value. For this reason, the present invention can add an extreme voltage detecting circuit 470, lightly connect a plurality of current balancing terminals m~Dn, and generate a feedback signal FB4 according to the lowest potential between the current balancing terminals D1~Dn. The extreme voltage detection circuit 470 can include a plurality of two In the polar body, the negative ends thereof are respectively connected to a plurality of current balancing terminals D1 to Dn, and the positive terminals thereof are connected to each other and coupled to a driving power source VCC through a resistor. Thus, the electrolytic balance end with the lowest potential of * The corresponding diode can be turned on. The remaining diodes cannot be turned on in principle due to insufficient voltage across the voltage, so that the potential of the feedback signal FB4 is the lowest potential of the current balance terminal plus the forward bias of the one pole. Then, the circuit operation mode of the feedback control is substantially the same as the circuit shown in the third figure of the present invention, and will not be described herein. As described above, the present invention fully complies with the three requirements of the patent: novelty, advancement, and industry. The invention has been described above in terms of the preferred embodiments, and it should be understood by those skilled in the art that the present invention is only intended to illustrate the invention and should not be construed as limiting the scope of the invention. All changes and substitutions that are equivalent to the embodiments are intended to be included within the scope of the present invention. Therefore, the scope of the invention is defined by the scope of the following claims.
13 201223317 Γ 【圖式簡單說明】 第一圖為一習知之發光二極體驅動電路之電路示意圖。 第二圖為根據第一圖所示之發光二極體驅動電路於調光過程 的訊號波形圖。 第二圖為根據本發明之一第一較佳實施例之一發光二極體驅 動電路之電路示意圖。 第四圖為根據本發明之一第一較佳實施例於調光過程的訊號 波形圖。 第五圖為根據本發明之一第二較佳實施例之一發光二極體驅 動電路之電路示意圖。 第六圖為根據本發明之一第三較佳實施例之一發光二極體驅 動電路之電路示意圖。 第七圖為根據本發明之一第二較佳實施例於調光過程的訊號 波形圖。 【主要元件符號說明】 先前技術： 回授控制電路1〇〇 脈寬控制單元110 脈寬調變單元112 驅動電路114 回授單元120 放大單元122 補償單元124 轉換電路130 發光二極體模組140 調光訊號DIM 輸入電壓VIN 輸出電壓VOUT 電流偵測電阻Ri 201223317 控制訊號Scl 電流回授訊號IFB1 參考訊號Vr 脈寬調變訊號S1 脈寬控制訊號Veal 誤差穩定值Vealo 臨界電壓Vf 時間點T1〜T5 預定輸出電壓Vo 預定輸出電流Ιο 本發明： 回授控制電路200、300、400 脈寬控制單元210、310 脈寬調變單元212、312 驅動電路214、314 調光控制單元216、316 調光關閉控制單元217、317 或閘 218、318 調光器319 回授單元220、320 放大單元222 訊號疊加單元324 補償單元224 回授開關226 轉換電路230、330、430 電壓偵測電路332 發光二極體模組240、340、440 驅動開關350、450 電流平衡單元460 15 ,'Γifirr η Γ 201223317 「 極端電壓偵測電路470 調光訊號DIM 輸入電壓VIN 輸出電壓VOUT 驅動電源VCC 電流偵測電阻Ri 電流源Is 控制訊號Sc2、Sc3、Sc4 回授訊號FB3、FB4 電流回授訊號IFB2、IFB3 電壓回授訊號VFB3 φ 第一參考訊號Vrl 第二參考訊號Vr2 第三參考訊號Vr3 脈寬調變訊號S2、S3 脈寬控制訊號Vea2、Vea3 誤差穩定值Vea2o 臨界電壓Vf 臨界參考電壓Vf 時間點tl〜t4 · 電流平衡端D1〜Dn 預定輸出電壓Vo 預定輸出參考電壓Vo’ 預定輸出電流1〇 預定輸出參考電流1〇，13 201223317 Γ [Simple description of the diagram] The first figure is a circuit diagram of a conventional LED driving circuit. The second figure is a signal waveform diagram of the dimming process according to the LED driving circuit shown in the first figure. The second figure is a circuit diagram of a light-emitting diode driving circuit according to a first preferred embodiment of the present invention. The fourth figure is a waveform diagram of a signal during a dimming process in accordance with a first preferred embodiment of the present invention. Figure 5 is a circuit diagram showing a light-emitting diode driving circuit according to a second preferred embodiment of the present invention. Figure 6 is a circuit diagram showing a light-emitting diode driving circuit according to a third preferred embodiment of the present invention. Figure 7 is a waveform diagram of a signal during a dimming process in accordance with a second preferred embodiment of the present invention. [Main component symbol description] Prior art: feedback control circuit 1 〇〇 pulse width control unit 110 pulse width modulation unit 112 drive circuit 114 feedback unit 120 amplification unit 122 compensation unit 124 conversion circuit 130 light emitting diode module 140 Dimming signal DIM Input voltage VIN Output voltage VOUT Current detecting resistor Ri 201223317 Control signal Scl Current feedback signal IFB1 Reference signal Vr Pulse width modulation signal S1 Pulse width control signal Veal Error stability value Vealo Threshold voltage Vf Time point T1~T5 Predetermined output voltage Vo predetermined output current Ιο The present invention: feedback control circuit 200, 300, 400 pulse width control unit 210, 310 pulse width modulation unit 212, 312 drive circuit 214, 314 dimming control unit 216, 316 dimming off Control unit 217, 317 or gate 218, 318 dimmer 319 feedback unit 220, 320 amplification unit 222 signal superimposition unit 324 compensation unit 224 feedback switch 226 conversion circuit 230, 330, 430 voltage detection circuit 332 light emitting diode Modules 240, 340, 440 drive switches 350, 450 current balancing unit 460 15 , 'Γifirr η Γ 201223317 "Extreme voltage detection circuit 470 Optical signal DIM input voltage VIN output voltage VOUT drive power supply VCC current detection resistor Ri current source Is control signal Sc2, Sc3, Sc4 feedback signal FB3, FB4 current feedback signal IFB2, IFB3 voltage feedback signal VFB3 φ first reference signal Vrl second reference signal Vr2 third reference signal Vr3 pulse width modulation signal S2, S3 pulse width control signal Vea2, Vea3 error stability value Vea2o threshold voltage Vf critical reference voltage Vf time point t1 ~ t4 · current balance terminal D1 ~ Dn Output voltage Vo predetermined output reference voltage Vo' predetermined output current 1 〇 predetermined output reference current 1〇,
調光控制訊號Ρ2、Ρ3 橋式整流器BD 交流輸入電源VAC 變壓器T 電晶體開關SW 16 201223317Dimming control signal Ρ2, Ρ3 Bridge rectifier BD AC input power VAC Transformer T transistor switch SW 16 201223317
整流二極體D 輸出電容C 直流訊號DC 設定端S 重設端R 輸出端Q 輸出電流IOUT 時脈訊號PURectifier Diode D Output Capacitor C DC Signal DC Set Terminal S Reset Terminal R Output Terminal Q Output Current IOUT Clock Signal PU