200930147 九、發明說明： 【發明所屬之技術領域】 本發明係為一種具調光功能之發光二極體驅動電路及 其二次側控制器，尤指一種於調光過程，可將發光二極體 驅動電壓控制於一第一驅動電壓及一第二驅動電壓之發光 二極體驅動電路及其二次侧控制器。 【先前技術】 如第一圖所示，為習知的降壓式（Buck)發光二極體驅❽ 動電路。當電晶體開關Q2導通（TURN 0N )時，電源V4提 供電流流經電晶體開關Q2對電感L1、電容C4充電儲能並 同對發光一極體D2、D5提供能量使其發光。當電晶體開 關Q2關閉（TURN OFF)時再由電感L1、電容C4釋放能量讓 發光二極體D2、D5持績發光。流經發光二極體j)2、D5的 電流會在電阻R7兩端產生電壓降而產生一電流偵測訊 號。誤差放大器U4的負輸入端接收該電流偵測訊號，正輸 入端接收一電壓參考訊號Vref，據此於輸出端輸出一誤差® 放大訊號。脈寬調變（Pulse Width Modulated，PWM)比 較器U5接收該誤差放大訊號及一三角波訊號，比較該兩訊 號後輸出一 PWM訊號，以決定電晶體開關Q2在每個週期的 導通時間，而達到控制電源V4對降壓式發光二極體驅動電 路提供能量的多寡。基本上電晶體開關Q2的的導通時間會 由迴授電壓控制讓電路輸出足夠電壓及電流，使得電阻R7 感測電流專於預没值，如果輸出電流太多或太少，電阻R7 200930147 兩端的電壓就會變化，進而改變電晶體開關Q2的導通時 間，如此會把電阻R7兩端的電壓為持在定值，達到電流穩 流。 請再參考第一圖，利用一反及閘（NAND gate) U7A同 曰守接收—調光訊號DIM及該PWM訊號而達到調光的功能。 當輸入調光訊號為低準位時a〇WLEVEL)’使反及閘U7A的 輸出轉為高準位停止功率電晶體開關Q2導通。雖然電晶體 開關Q2截止後電感li及電容C4會透過二極體D8釋放能 ❹量維持發光二極體D2、D5,然而由於調光訊號的週期較長， 電感L1及電容C4會釋放能量至輸出電壓（電感L1及電容 C4的接點電壓）低於發光二極體D2、D5的臨界電壓時， 發光二極體D2、D5不再發光。然而由於一些漏電路徑的存 在，輸出電壓依然會持續下降至電感L1及電容C4的儲能 完全釋放為止。當輪入調光信號轉為高準位時（幻邱 LEVEL)，反及閘U7A的輸出轉為受p丽訊號控制，將恢復 ❹如前述的迴授控制而達到穩定發光。如此藉由控制訊號脈 波寬度變化進而控制LED點亮與關暗時間比例而得到〜平 均亮度而達成的調光方式。 此習知的調光方式因為作用在導通與截止兩者極端， 將產生過Λ暫態電壓，其動作電壓電流波形如第二圖所 示，其電麈變化為零伏特到N*VF，其中Ν為串聯的發先二 極體數量，為發光二極體流經預定電流的跨壓，如有數 十個串聯LED，其兩端的電壓變化將達數百伏特。而其中 的IPVFmin係指發光二極體處於臨界電壓時所造成的跨 200930147 壓，當輸出電壓由_VF下降至N*VFmin時，發光二極體幾 乎停止發光’如第二圖所示此時電容儲能的釋放速度將變 緩慢直至完全釋放。由於發光二極體的再次導通需要導通 時間，當瞬間提供的電壓過大，在多顆串聯發光二極體中 將有因導通不同而將承受大於規格甚多的電壓應力使發光 二極體危險情形發生，因此必須提供電壓緩升控制電 路。雖然藉由加入電壓緩升控制電路可以解決上述之問 題，然此舉不僅增加了發光二極體驅動電路的成本，而且 調光過程的電壓升降的暫態時間亦會增長而影響調光控❹ 的精確度。 工 【發明内容】 有鐘於此，本發明乃提供一種當發光二極體 =時仍可在發光二極體肋兩端維持—基本電壓，使其能 發:在極體模組兩端輸入有較小電壓高低變化，使 發光二極體驅動雷政夕於、t m 便 ❹ 時間而另辦加链 〇 W 1不用时慮輸出電壓上升 無損壞危二來保障發光二極體元件 簡化_路板的發光二極體驅動電路成本與 為達上述目的，本發明提供 路，包含-轉換電路、一發光 先-極體驅動電 及-控制H上賴=極體触、—電流偵测器 電_換成-輸出耗根據—控制訊號將一輸入 電路，並根據該輪出輸發：先二極體模組耦接該轉換 出錢而發光。上述電—_該 200930147 發光二極體模組，根據流經該發光二極體模組之一電流產 生一電流偵測訊號。上述控制模組根據該電流偵測訊號及 一調光訊號產生該控制訊號，使該輪出電壓被控制在—第 -驅動電壓或-第二驅動電壓。其中，當該輸出電壓位於 該第一驅動電壓時，該發光二極體模組處於穩定的發光狀 態；而當輸出電壓位於該第二驅動電壓時，該輸出電壓約 接近該發光二極體模組的-臨界電愿，使該發光二極體模 組幾乎不發光。 Ο ❹ 本發明亦提供另一種發光二極體驅動電路，包含—轉 換電路、-發光二極體模組、—電流偵測器、一電壓偵測 器以及-控制模組。上述轉換電路係根據一控制訊號將一 輸入電壓轉換成-輸出電壓。上述發光二極體模組叙接該 轉換電路，並根據該輸出電壓而發光。上述電流 接該發光二極體模組，根據流經該發光二極體模組之一電 流產生一電流偵測訊號。上述電壓偵測器耦接該發光二極 體模組，以根據施加於該發光二極體模組之一電^產:一 電壓偵測職。上述控龍組根據該電流_訊號、 =偵測訊號及-調光訊號，產生該㈣職，使該輪出\ 壓被控制在-第—驅動電屋或—第二驅動電壓。其中，* 該輸出電壓位於該第一驅動電壓時，該發光二極體楔』 於穩定的發光狀態；而當輸出電壓位於該第二驅動雷厭 時’該輸出電壓約接近該發光二極體模組的—臨界電屋， 使該發光二極體模組幾乎不發光。 本發明也提供一種二次側控制電路’其應用於一發光 200930147 二極體驅動電路，其中該發光二極體驅動電路包含 侧控制電路、-轉換電路及1接於該熟電路之二 债測器，該二次側控制電路_該至少―_[上 二次侧控制電路可以包含-訊號處理器及—訊_ ❹ 路。其中，上述訊號處理器耦接該至少—偵測器，並根據 該至少-侧器所產生之至少—偵測訊號產生對應之至少 -處理訊號；上述之訊㈣擇電路，_該訊號處理器並 根據一調光訊號選擇輸出該至少一處理訊號之一。另外， 上述之二次側㈣電路也可以是包含—訊號轉電路及一 訊號處理器。其中，上述訊號選擇電路減該至少一侦測 器並根據一調光訊號選擇輸出所接收訊號之一；上述訊號 處理器_該訊號選擇電路，並根據該訊號轉電路所產u 生之訊號輸出一處理訊號。 【實施方式】 本發明之精神在於在調光控制過程，發光二極體驅動 電路的輸出電壓被控制在一第一驅動電壓或—第二驅動電 壓。當輸出電麗位於第一驅動電壓時，發光二極體模組為 電流迴授控制，故處於穩定的發光狀態；而當輪出電壓位 於第二驅動電塵時’為電壓迴授控制’故該輪出電壓約略 位於發光二極體模組的臨界電壓（但大於零伏特），使發 光二極體模組幾乎不發光’較佳為略小於發光二極體模組 的臨界電壓，以確保發光二極體模組不發光。如此，在調 光過程，施加於發光二極體模組的電壓變化小於習知的電 200930147 尾變化古支可避免習知技藝中發光二極體受到過 力或調光控制不精確之問題。&應 為了達到上述的控制，可以使用定電流、定電壓切拖 或者定電流及最小卫作週期城的方式來實施。以美 本發明的一些較佳實施例來說明。 ' u 第二A圖為根據本發明定電流/定電壓切換之笋 極體驅動電路之電路示意圖。如第三A圖所示，.一 體驅動電路包含—轉換電路1〇、一控制模組、一發了 5 〇體模組30、一電流伯測器32以及-電壓伯測器34。^ 模組包含二次側控制單元12、—二次侧控制單元20^ 及一隔離單元36。轉換電路10根據一次侧控制單元12的 控制訊號’將—輸入電壓VIN轉換成一輸出電壓VO，以 供驅動發光二極體模組3〇之用。電壓偵測器34偵測發光 一極體模組30的電壓，以輪出一電壓偵測訊號；電流偵測 器32與發光二極體模組3〇串聯’偵測流經發光二極體模 ❹組30的電流以產生一電流偵測訊號。二次侧控制單元20a 接收該電壓债測訊號、該電流偵測訊號及一調光訊號，並 據此產生一二次側控制訊號，並經隔離單元3 6後傳送到一 -人侧控制單το 12 ’隔離單元36在本實施例中係為光耦合 器’在實際應用時可以是變壓器或其他隔離元件。一次側 控制單元12可以是習知的ρ·控制器，其根據該二次側控 制矾號產生上述控制訊號，以控制轉換電路1〇將輸入電壓 轉換成輸出電壓V0。在本實施例中，轉換電路1〇係以返 驰式直流轉直流轉換電路為例說明，而實際應用上可為順 11 200930147 向式、半橋式、全橋式專轉換電路而不受限。 二次侧控制單元20a包含了電屋偵測訊號處理器 24a、電流偵測訊號處理器26a以及訊號選擇電路28a。電 壓偵測訊號處理器24a接收電壓偵測訊號及調光訊號，並 據此產生一電壓處理訊號；而電流偵測訊號處理器26a接 收電流偵測訊號’以產生一電流處理訊號。訊號選擇電路 2 8 a•接收電壓處理訊被以及電流處理訊號，並根據兩者訊 號的大小不同選擇輸出其中之一。在本實施例中，調光訊 號為脈衝訊號並輸入至電壓偵測訊號處理器24a，以調整Ο 電壓偵測訊號處理器24a輸出的電壓處理訊號大小。 電壓偵測訊號處理器24a包含訊號選擇器241a及誤差 放大器242a。訊號選擇器241a根據調光訊號選擇輸出較 高之第一參考電壓Vrefl或較低之第二參考電壓vref2。 誤差放大器242a之非反相輸入端接收訊號選擇器241a所 輸出的第一參考電壓Vrefl或第二參考電壓Vref 2，反相 輸入端接收電壓偵測器34的電壓偵測訊號，並據此輸出電q 壓處理訊號。電流偵測訊號處理器26a係為誤差放大器， 於非反相輸入端接收第三參考電壓Vrefl，反相輸入端接 收電流债測器32的電流偵測訊號，並據此輸出電流處理訊 號。訊號選擇電路28a包含兩個二極體，該些二極體的負 端分別麵接電壓偵測訊號處理器24a及電流偵測訊號處理 器26a ’正端則均耦接至隔離單元36，並選擇輸出電壓處 理訊號及電流處理訊號之中較低準位者。在本實施例中， 當調光訊號準位為代表「OFF」之第-準位訊號時，訊號選 12 200930147 擇器241a輸出較低之第二參考電壓Vref2，使電壓偵测訊 唬處理器24a降低所輸出之電壓處理訊號之準位。此時， 電壓處理訊號之準位低於電流處理訊號之準位，訊號選擇 電路28a選擇輸出電壓處理訊號。因此，發光二極體驅動 電路操作在定電壓模式，使輸出電壓降至發光二極體模組 的臨界電壓附近，此時發光二極體模組幾乎不發光。當調 光訊號準位為代表「⑽」之第二準位訊號時，訊號選擇器 241a輸出較高之第―參考電壓Vrefl，使電壓偵測訊號處 理器24a提高所輸出之電壓處理訊號之準位。此時，訊號 選擇電路28a選擇輪出電流處理訊號。因此，發光辦 驅動電路㈣奴電流模式，輸出電壓上升而使發光二極 體，組的電流穩定於—預定電流值，此時發光二極體模組 穩定發光。如此，發光二極體驅動電路之輸出電壓在第— 驅動電壓（定電流模式，電流穩定於-預定電流值）或笫 二驅動電壓（定電壓模式，電壓穩定於-預定電壓值）， 〇兩驅動電壓之差較小而避免前述習知技藝中之問題 外，若電路發生開路’使電流_器3 2迴授的電流俄測气 鮮錄低’此時輪4電壓VQ會不斷上升至縣價 34的電壓個訊_達第_參考電壓ν^ι為止，此時 ^貞測訊號處理H 24a再度取得迴授㈣絲權，限制輪 出電壓V0的最大值而達到過壓保護功能。 3 當然，調光訊號除如上述可控制電壓侧訊號處理器 4a之非反相輸人端之輪人訊號達到控制輸出訊號之準位 外’亦可為控制電壓_訊號處理器⑽之反相輸入端之 13 200930147 輸入訊號之準位或直接控制電壓偵測訊號處理号恤 出端輸出訊號之準位等手段來達到上述功能，其之輪 控制電流偵測訊號處理器26a之任一n 、 ’、可為 來達到前述功能。參考第三β圖，為批生 〇说 為控制誤差放大器242a 之反相輸入知之輸入訊號準位之發光二拖體驅動電路示音 圖。在本實施例中，電壓_器34包含第—分壓部34^ 第二分壓部34b，利用訊號選擇器241a 益Z41a切換電壓偵測器34 的分壓比例，輯到切換發光二極_動電路料電流模 式或定電壓模式之功能。 ^ 另外’實際應用上，調光訊號可為直流調光、脈衝訊 號或dock調光（即於-預定時間長度内計算山仏訊號 的數量，而換算成調光的工作週期）等而不受限。以下， 另一較佳實施例以直流調光來說明。 .第三C圖為根#本發明之-直流調光（即以調光訊號 的準位高低代表調光的幅度）實施例之發光二極體驅動電 路示意圖。其中，二次側控制單元2〇b包含了訊號處理器 24b以及訊號選擇電路28b。訊號選擇電路28b接收直流調 光訊號、電壓偵測訊號及電流偵測訊號，並基於直流調光 訊號而選擇輸出電壓谓測訊號及電流偵測訊號之一至訊號 處理器24b，訊號處理器24b根據所接收之電壓偵測訊號 或電流偵測訊號而輸出訊號至一次側控制單元12，使一次 側控制單元12據此控制轉換電路1 q。本實施例相較於第 二A圖所示實施例，除調光訊號為直流訊號外，亦將訊號 選擇電路前置而可節省訊號處理器之數量。 14 200930147 訊號選擇電路28b包含一直流轉脈衝轉換器281b、一 準位調整器282b以及一訊號選擇器283b。直流轉脈衝轉 換器281b可以為一比較器，非反相輸入端接收直流調光訊 號、反相輸入端接收一三角波訊號，並據此輸出一脈衝訊 號。準位調整器282b調整所接收之電流偵測訊號準位，使 電流偵測訊號之準位調整成和電壓偵測訊號之準位在同一 ‘範圍。訊號選擇器283b接收準位調整器282b所輪出.的電 〇 流偵測訊號和電壓偵測器34所輸出的電壓偵測訊號，並根 據直流轉脈衝轉換器281b輸出的脈衝訊號選擇輪出電流 谓測訊號或電壓偵測訊號。訊號處理器24b為一誤差放大 電路，非反向輸入端接收一參考電壓Vref，反向輪入端接 收訊號選擇器283b所輸出之訊號，並據此輸出二次側控制 訊號至隔離單元36。隔離單元36耦接一稽納二極體 38(zenerdiode)，做為輸出過壓保護，於電路異常而造成 輸出電壓V0異常上升時’箝制輸出電壓v〇於一最大輪出 〇 電壓值。 月』 在本實施例中，當直流轉脈衝轉換器281b輸出的脈衝 訊號準位為代表「0FF」之第一準位訊號時，訊號選擇器 283b輸出電壓偵測訊號。因此，發光二極體驅動電路操作 在定電壓模式，使輸出電壓降至發光二極體模組的臨界電 壓附近，此時發光二極體模組幾乎不發光。當直流轉脈衝 轉換盜281b選擇輸出的脈衝訊號準位為代表r on」之第一 準位訊號時，訊號選擇器283b選擇輸出電流偵測訊號。因 此’發光二極體驅動電路操作在定電流模式，輸出電壓上 15 200930147 升而使發光二極體模組的電流穩定於一預定電流值，此時 發光二極體模組穩定發光。 如前所述，本發明亦可以定電流及最小工作週期切換 的方式來實施。請參考第三D圖，為根據本發明定電流及 最小工作週期切換之—較佳實施例之電路示意圖。二次侧 控制單元20c包含-訊號處理器24c、一最小工作週期訊 號產生器29c以及—訊號選擇！！ 28c。訊號處理器撕為 一誤差放大器’根據電流偵測器32所產生的電流铺測訊號 及-參考電壓而輸出-電流處理訊號。最小工作週期訊號❹ 產生器29c可由外部來設定最小工作週期之大小，以配合 不同應用環境來調整，如：實施例所示般由外部之電阻， 或者由電容或其他方式來設定。訊號選擇器28c接收電流 處理訊號及最小工作週期訊號產生器29c所產生的一最小 工作適期訊號，並根據調光訊號DIM遘擇其一輸出。一次 侧控制單元12c接收透過隔離單元36所傳送之二次侧控制 單70 20c輸出之訊號，並據此控制轉換電路1〇。 Ο 在本實施例中，當調光訊號DIM之準位為代表「〇FF」 之第一準位訊號時，訊號選擇器28c選擇輸出最小工作週 4訊號。經適當的設定最小工作週期，一次側控制單元I〗。 根據最小工作週期訊號所輸出的控制訊號的工作週期極 J、，使經轉換電路1〇傳至二次側的能量約略可維持發光二 極體模組3〇以外的電路元件之基本損耗。也就是說當驅動 電壓降至發光二極體模組3〇之臨界電壓附近後，停止下降 而維持在一電壓值左右，此時發光二極體模組幾乎不發 16 200930147 光。當調光訊號DIM之準位為代表「⑽」之第二準位訊號 枯’ Λ就選擇器28c選擇輸出電流偵測訊號。因此，發光 —極體驅動電路操作在定紐模式，輸出電壓上升而使發 光二極體模組的電流穩定於一預定電流值，此時發光二極 體模組穩定發光。 4參見第四圖，為根據本發明之該些實施例之發光二 極體模_賴電壓及驅動電缝料意圖。在調総號 IM為代表⑽」之準位時，發光二極體模組的驅動電壓 為維持在第一驅動電壓胸F附近，此時的發光二極體模組 驅動電流並穩定地控制在1;在調光訊冑酿為代表「〇ff」 之準位時，發光二極體模組的驅動電壓維持在第二驅動電 壓卿min附近，此時發光二極體模組驅動電流為零（或 接近零）。如此，在發光二極體的驅動電壓變化較習知技 藝的驅動電壓變化為小下，依然可達到謫光功能。 如上所述，本發明完全符合專利三要件：新顆性、進 ❹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 緣本發明，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#内。因此’本發明之保護_當以下文之 ^ 利範圍所界定者為準。 ° 【圖式簡單說明】 第-圖為習知的降M^(BuGk)發光二極魅動電路； 17 200930147 第二圖為習知的發光二極體驅動電路之驅動電壓及驅動電 流波形不' 意圖， 第三A圖至第三D圖為根據本發明之發光二極體驅動電路 之電路示意圖；以及 第四圖為為根據本發明之該些實施例之發光二極體模組的 驅動電壓及驅動電流波形示意圖。 【主要元件符號說明】 10 轉換電路 12 一次側控制單元 12c 一次侧控制單元 20a 二次侧控制單元 20b 二次側控制單元 24a 訊號處理器 24b 訊號處理器 24c 訊號處理器 242a 誤差放大器 241a 訊號選擇器 26a 訊號處理器 28a 訊號選擇電路 28b 訊號處理器 28c 訊號選擇器 281b 直流轉脈衝轉換器 282b 準位調整器200930147 IX. Description of the invention: [Technical field of the invention] The present invention is a light-emitting diode driving circuit with a dimming function and a secondary side controller thereof, especially a dimming process, which can emit a light-emitting diode The body driving voltage is controlled by a first driving voltage and a second driving voltage of the LED driving circuit and the secondary side controller thereof. [Prior Art] As shown in the first figure, it is a conventional buck LED driving circuit. When the transistor switch Q2 is turned on (TURN 0N ), the power supply V4 supplies current through the transistor switch Q2 to charge and store the inductor L1 and the capacitor C4, and provides energy to the light-emitting diodes D2 and D5 to emit light. When the transistor switch Q2 is turned off (TURN OFF), the energy is released from the inductor L1 and the capacitor C4 to cause the light-emitting diodes D2 and D5 to emit light. The current flowing through the LEDs j) 2, D5 produces a voltage drop across the resistor R7 to produce a current sense signal. The negative input terminal of the error amplifier U4 receives the current detection signal, and the positive input terminal receives a voltage reference signal Vref, thereby outputting an error® amplification signal at the output end. Pulse Width Modulated (PWM) comparator U5 receives the error amplification signal and a triangular wave signal, compares the two signals and outputs a PWM signal to determine the on-time of the transistor switch Q2 at each cycle. Control power supply V4 provides energy to the buck LED driver circuit. Basically, the on-time of the transistor switch Q2 is controlled by the feedback voltage to allow the circuit to output sufficient voltage and current, so that the sense current of the resistor R7 is dedicated to the pre-no value. If the output current is too much or too little, the resistor R7 200930147 The voltage will change, and then change the on-time of the transistor switch Q2, so that the voltage across the resistor R7 is held at a constant value to achieve current stabilization. Please refer to the first figure again, and use a NAND gate U7A to observe the receive-dimming signal DIM and the PWM signal to achieve the dimming function. When the input dimming signal is at the low level, a〇WLEVEL)' turns the output of the anti-gate U7A to a high level to stop the power transistor switch Q2 from being turned on. After the transistor switch Q2 is turned off, the inductor li and the capacitor C4 can release the light-emitting diodes D2 and D5 through the diode D8. However, since the period of the dimming signal is long, the inductor L1 and the capacitor C4 release energy to When the output voltage (the contact voltage of the inductor L1 and the capacitor C4) is lower than the threshold voltage of the light-emitting diodes D2 and D5, the light-emitting diodes D2 and D5 no longer emit light. However, due to the existence of some leakage paths, the output voltage will continue to drop until the energy storage of the inductor L1 and the capacitor C4 is completely released. When the wheel dimming signal turns to the high level (Falley LEVEL), the output of the reverse gate U7A is controlled by the P signal, which will return to the feedback control as described above to achieve stable illumination. In this way, the dimming mode achieved by controlling the ratio of the pulse width of the signal to the LED lighting and the darkening time ratio to obtain the average brightness is obtained. This conventional dimming mode will generate an over-transient transient voltage because it acts at both the on and off limits. The action voltage and current waveforms are as shown in the second figure, and the eDonkey changes from zero volts to N*VF. The number of first-order diodes in series is the voltage across the predetermined current flowing through the LED. If there are dozens of LEDs in series, the voltage across them will vary by hundreds of volts. The IPVFmin refers to the voltage across the 200930147 caused by the LED being at the threshold voltage. When the output voltage drops from _VF to N*VFmin, the LEDs almost stop emitting light as shown in the second figure. The release rate of the capacitor energy storage will be slow until it is completely released. Since the re-conduction of the light-emitting diode requires an on-time, when the voltage supplied in an instant is too large, a plurality of series-connected light-emitting diodes will have a voltage stress greater than a specification due to different conduction, thereby causing a dangerous situation of the light-emitting diode. Occurs, so a voltage ramp control circuit must be provided. Although the above problem can be solved by adding a voltage ramp control circuit, this not only increases the cost of the LED driving circuit, but also increases the transient time of the voltage rise and fall of the dimming process and affects the dimming control. The accuracy. [Invention] The present invention provides a basic voltage that can be maintained at both ends of a light-emitting diode rib when the light-emitting diode = to enable it to be emitted at both ends of the polar body module. There is a small voltage change, so that the light-emitting diode drives the Lei Zhengxi, tm, and the time is added, and the additional chain is added. When the W1 is not used, the output voltage rises without damage, and the light-emitting diode component is simplified. The cost of the LED light-emitting diode driving circuit and the above-mentioned purpose, the present invention provides a circuit, including-conversion circuit, a light-emitting first-pole body driving power, and a control H-substrate=polar body touch, current detector power _changed-output consumption--the control signal will be an input circuit, and according to the round-off transmission: the first diode module is coupled with the conversion money to emit light. The above-mentioned 2009-30147 LED module generates a current detecting signal according to a current flowing through the LED module. The control module generates the control signal according to the current detection signal and a dimming signal, so that the wheel voltage is controlled to be a -first driving voltage or a second driving voltage. Wherein, when the output voltage is at the first driving voltage, the LED module is in a stable illumination state; and when the output voltage is at the second driving voltage, the output voltage is approximately close to the LED mode. The group-critical electricity is such that the light-emitting diode module hardly emits light. Ο ❹ The present invention also provides another LED driving circuit comprising a conversion circuit, a light emitting diode module, a current detector, a voltage detector and a control module. The conversion circuit converts an input voltage into an output voltage according to a control signal. The light emitting diode module is connected to the conversion circuit and emits light according to the output voltage. The current is connected to the LED module, and a current detecting signal is generated according to a current flowing through the LED module. The voltage detector is coupled to the LED module to generate a voltage detection function according to one of the LED modules. The above-mentioned control group generates the (four) position according to the current_signal, the = detection signal and the - dimming signal, so that the round-out pressure is controlled in the -first driving electric house or the second driving voltage. Wherein, when the output voltage is at the first driving voltage, the LED wedge is in a stable lighting state; and when the output voltage is in the second driving radar, the output voltage is close to the LED The module's critical electric house makes the light-emitting diode module emit almost no light. The present invention also provides a secondary side control circuit for applying to a light emitting 200930147 diode driving circuit, wherein the light emitting diode driving circuit comprises a side control circuit, a conversion circuit, and a second debt test connected to the cooked circuit. The secondary side control circuit _ the at least ―[the upper secondary side control circuit may include a signal processor and a signal channel. The signal processor is coupled to the at least one detector, and generates at least a corresponding processing signal according to at least the detection signal generated by the at least one side device; the fourth signal selection circuit, the signal processor And selecting one of the at least one processing signal according to a dimming signal. In addition, the above secondary (four) circuit may also include a signal conversion circuit and a signal processor. The signal selection circuit reduces the at least one detector and selects one of the received signals according to a dimming signal; the signal processor _ the signal selection circuit and outputs the signal according to the signal generated by the signal conversion circuit A processing signal. [Embodiment] The spirit of the present invention resides in that during the dimming control process, the output voltage of the LED driving circuit is controlled to a first driving voltage or a second driving voltage. When the output current is at the first driving voltage, the LED module is in current feedback control, so it is in a stable lighting state; and when the wheeling voltage is in the second driving dust, it is 'voltage feedback control' The turn-off voltage is approximately at the threshold voltage of the LED module (but greater than zero volts), so that the LED module hardly emits light. Preferably, it is slightly smaller than the threshold voltage of the LED module to ensure The LED module does not emit light. In this way, during the dimming process, the voltage applied to the LED module is less than that of the conventional electronic control system. In the prior art, the problem that the LED is subjected to excessive force or dimming control is not accurate. & In order to achieve the above control, it can be implemented by means of constant current, constant voltage cut or constant current and minimum guard cycle. This is illustrated by some preferred embodiments of the invention. ' u The second A diagram is a circuit diagram of the pole body driving circuit of the constant current/constant voltage switching according to the present invention. As shown in FIG. 3A, the one-body driving circuit includes a conversion circuit 1A, a control module, a 5-body module 30, a current detector 32, and a voltage detector 34. ^ The module includes a secondary side control unit 12, a secondary side control unit 20^, and an isolation unit 36. The conversion circuit 10 converts the input voltage VIN into an output voltage VO according to the control signal of the primary side control unit 12 for driving the LED module 3. The voltage detector 34 detects the voltage of the LED module 30 to turn on a voltage detection signal; the current detector 32 is connected in series with the LED module 3' to detect the flow through the LED. The current of the group 30 is simulated to generate a current detection signal. The secondary side control unit 20a receives the voltage debt measurement signal, the current detection signal and a dimming signal, and generates a secondary side control signal accordingly, and transmits the signal to the one-person side control unit via the isolation unit 36. The το 12 'isolation unit 36 in the present embodiment is an optocoupler' which may be a transformer or other isolation element in practical use. The primary side control unit 12 may be a conventional ρ·controller that generates the above control signal based on the secondary side control nickname to control the conversion circuit 1 to convert the input voltage to the output voltage V0. In this embodiment, the conversion circuit 1 is described by taking a flyback DC-to-DC conversion circuit as an example, and the practical application can be an compliant, non-restricted, half-bridge, full-bridge conversion circuit. . The secondary side control unit 20a includes an electric house detection signal processor 24a, a current detection signal processor 26a, and a signal selection circuit 28a. The voltage detection signal processor 24a receives the voltage detection signal and the dimming signal, and generates a voltage processing signal accordingly. The current detection signal processor 26a receives the current detection signal ' to generate a current processing signal. Signal selection circuit 2 8 a• Receive voltage processing signal and current processing signal, and select one of the outputs according to the size of the two signals. In this embodiment, the dimming signal is a pulse signal and is input to the voltage detecting signal processor 24a to adjust the voltage processing signal output by the voltage detecting signal processor 24a. The voltage detection signal processor 24a includes a signal selector 241a and an error amplifier 242a. The signal selector 241a selects to output a higher first reference voltage Vref1 or a lower second reference voltage vref2 according to the dimming signal. The non-inverting input terminal of the error amplifier 242a receives the first reference voltage Vref1 or the second reference voltage Vref2 outputted by the signal selector 241a, and the inverting input terminal receives the voltage detection signal of the voltage detector 34, and outputs the voltage detection signal according to the output. Electric q pressure processing signal. The current detecting signal processor 26a is an error amplifier, and receives a third reference voltage Vref1 at the non-inverting input terminal, and the inverting input terminal receives the current detecting signal of the current debt detector 32, and outputs a current processing signal according to the current detecting signal. The signal selection circuit 28a includes two diodes, and the negative ends of the diodes are respectively connected to the voltage detection signal processor 24a and the current detection signal processor 26a's positive ends are coupled to the isolation unit 36, and Select the lower level of the output voltage processing signal and current processing signal. In this embodiment, when the dimming signal level is the first-level signal representing "OFF", the signal selection 12 200930147 selector 241a outputs a lower second reference voltage Vref2, so that the voltage detection signal processor 24a lowers the level of the output voltage processing signal. At this time, the level of the voltage processing signal is lower than the level of the current processing signal, and the signal selecting circuit 28a selects the output voltage processing signal. Therefore, the LED driving circuit operates in a constant voltage mode, so that the output voltage is reduced to the vicinity of the threshold voltage of the LED module, and the LED module emits almost no light. When the dimming signal level is the second level signal representing "(10)", the signal selector 241a outputs a higher first reference voltage Vref1, so that the voltage detecting signal processor 24a increases the output voltage processing signal. Bit. At this time, the signal selection circuit 28a selects the round current processing signal. Therefore, the illuminating drive circuit (4) slave current mode, the output voltage rises to make the illuminating diode, the current of the group is stabilized at a predetermined current value, and the illuminating diode module is stably illuminated. Thus, the output voltage of the LED driving circuit is in the first driving voltage (constant current mode, current is stable at - predetermined current value) or second driving voltage (constant voltage mode, voltage is stable at - predetermined voltage value), If the difference between the driving voltages is small to avoid the problems in the prior art, if the circuit is open, the current of the current collector is returned to the current, and the current voltage of the wheel 4 is continuously rising to the county. The voltage of the price of 34 is up to the reference voltage ν^ι. At this time, the measurement signal processing H 24a again obtains the feedback (4) silk weight, and limits the maximum value of the wheel voltage V0 to reach the overvoltage protection function. 3 Of course, the dimming signal can be controlled by the control voltage _ signal processor (10), except that the wheel signal of the non-inverting input terminal of the voltage side signal processor 4a can be controlled to reach the level of the control output signal. The input terminal 13 200930147 input signal level or directly control the voltage detection signal to process the output level of the output end of the shirt to achieve the above functions, and the wheel controls any one of the current detection signal processor 26a, ', can be used to achieve the aforementioned functions. Referring to the third β-picture, the illuminating two-stolen drive circuit diagram for the input signal level of the inverting input of the control error amplifier 242a is referred to as a batch. In the present embodiment, the voltage_input unit 34 includes a first voltage dividing unit 34^ and a second voltage dividing unit 34b. The signal selector 241a is used to switch the voltage dividing ratio of the voltage detector 34 to the switching light emitting diode. The function of the current circuit current mode or constant voltage mode. ^ In addition, in practical applications, the dimming signal can be DC dimming, pulse signal or dock dimming (that is, calculating the number of mountain signals in a predetermined length of time, and converting to the duty cycle of dimming), etc. limit. Hereinafter, another preferred embodiment is illustrated by direct current dimming. The third C picture is a schematic diagram of the light-emitting diode driving circuit of the embodiment of the present invention - the direct current dimming (i.e., the level of the dimming signal represents the amplitude of the dimming). The secondary side control unit 2B includes a signal processor 24b and a signal selection circuit 28b. The signal selection circuit 28b receives the DC dimming signal, the voltage detection signal and the current detection signal, and selects one of the output voltage measurement signal and the current detection signal to the signal processor 24b based on the DC dimming signal, and the signal processor 24b is configured according to the signal processor 24b. The received voltage detection signal or current detection signal outputs a signal to the primary side control unit 12, so that the primary side control unit 12 controls the conversion circuit 1 q accordingly. Compared with the embodiment shown in FIG. 2A, in addition to the dimming signal being a DC signal, the signal selection circuit is also pre-positioned to save the number of signal processors. 14 200930147 The signal selection circuit 28b includes a continuous flow pulse converter 281b, a level adjuster 282b, and a signal selector 283b. The DC-to-pulse converter 281b can be a comparator. The non-inverting input receives the DC dimming signal, the inverting input receives a triangular wave signal, and a pulse signal is output therefrom. The level adjuster 282b adjusts the received current detection signal level so that the level of the current detection signal is adjusted to be in the same range as the level of the voltage detection signal. The signal selector 283b receives the electric current detection signal rotated by the level adjuster 282b and the voltage detection signal output by the voltage detector 34, and selects a round according to the pulse signal outputted by the DC pulse converter 281b. Current sense signal or voltage detection signal. The signal processor 24b is an error amplifying circuit. The non-inverting input terminal receives a reference voltage Vref, and the reverse wheel receiving terminal receives the signal outputted by the signal selector 283b, and outputs a secondary side control signal to the isolation unit 36 accordingly. The isolation unit 36 is coupled to a Zener diode 38 as an output overvoltage protection, and clamps the output voltage v to a maximum output voltage when the output voltage V0 rises abnormally. In the present embodiment, when the pulse signal level outputted by the DC-to-pulse converter 281b is the first level signal representing "0FF", the signal selector 283b outputs a voltage detection signal. Therefore, the LED driving circuit operates in a constant voltage mode to reduce the output voltage to the vicinity of the threshold voltage of the LED module, and the LED module emits almost no light. The signal selector 283b selects the output current detection signal when the pulse signal level of the DC-to-pulse conversion thief 281b is selected to represent the first level signal of r on". Therefore, the LED driving circuit operates in a constant current mode, and the output voltage is 15 200930147 liters to stabilize the current of the LED module at a predetermined current value, and the LED module is stably illuminated. As previously mentioned, the present invention can also be implemented in a manner that regulates current and minimum duty cycle switching. Please refer to the third D diagram for a circuit diagram of a preferred embodiment for switching current and minimum duty cycle in accordance with the present invention. The secondary side control unit 20c includes a signal processor 24c, a minimum duty cycle signal generator 29c, and a signal selection! ! 28c. The signal processor is torn into an error amplifier 'output-current processing signal according to the current spreading signal and the reference voltage generated by the current detector 32. The minimum duty cycle signal 产生 generator 29c can be externally set to the minimum duty cycle to be adjusted to suit different application environments, such as external resistors as shown in the embodiment, or by capacitance or other means. The signal selector 28c receives the current processing signal and a minimum duty signal generated by the minimum duty cycle signal generator 29c, and selects an output according to the dimming signal DIM. The primary side control unit 12c receives the signal output from the secondary side control unit 70 20c transmitted through the isolation unit 36, and controls the conversion circuit 1〇 accordingly. In this embodiment, when the level of the dimming signal DIM is the first level signal representing "〇FF", the signal selector 28c selects to output the minimum working week 4 signal. The primary side control unit I is set by appropriately setting the minimum duty cycle. According to the duty cycle J of the control signal outputted by the minimum duty cycle signal, the energy transmitted to the secondary side by the conversion circuit 1 can substantially maintain the basic loss of the circuit components other than the LED module 3. That is to say, when the driving voltage drops to the vicinity of the threshold voltage of the LED module 3, the voltage is stopped and maintained at a voltage value, and the LED module hardly emits 16 200930147 light. When the level of the dimming signal DIM is the second level signal representing "(10)", the selector 28c selects the output current detecting signal. Therefore, the illuminating-polar body driving circuit operates in the constant-state mode, and the output voltage rises to stabilize the current of the illuminating diode module to a predetermined current value, and the illuminating diode module stably emits light. 4 See the fourth figure, which is a schematic diagram of the light-emitting diode mode and the driving electric sewing material according to the embodiments of the present invention. When the IM is represented by the (10)", the driving voltage of the LED module is maintained near the first driving voltage, and the driving current of the LED module is stably controlled. 1; when the dimming signal is brewed to represent the "〇ff" level, the driving voltage of the LED module is maintained near the second driving voltage, and the driving current of the LED module is zero. (or close to zero). Thus, the dimming function can still be achieved when the driving voltage of the light-emitting diode changes less than the driving voltage of the conventional technique. As described above, the present invention fully complies with the three requirements of the patent: newness, advancement, and industrial applicability. 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 not intended to limit the scope of the invention. It should be noted that variations and permutations equivalent to those of the embodiment are intended to be included in the scope of the present invention. Therefore, the protection of the present invention is defined as defined in the following paragraphs. ° [Simple description of the figure] The first picture is a conventional M^(BuGk) light-emitting diode circuit; 17 200930147 The second picture shows the driving voltage and driving current waveform of the conventional LED driving circuit. 'Intention, the third to third D are schematic circuit diagrams of the LED driving circuit according to the present invention; and the fourth diagram is the driving of the LED module according to the embodiments of the present invention Schematic diagram of voltage and drive current waveforms. [Main component symbol description] 10 Conversion circuit 12 Primary side control unit 12c Primary side control unit 20a Secondary side control unit 20b Secondary side control unit 24a Signal processor 24b Signal processor 24c Signal processor 242a Error amplifier 241a Signal selector 26a signal processor 28a signal selection circuit 28b signal processor 28c signal selector 281b DC pulse converter 282b level adjuster
18 200930147 283b 訊號選擇器 29c 最小工作週期訊號產生器 30 發光二極體模組 32 電流偵測器 34 電壓偵測器 34a 第一分壓部 34b 第二分壓部 36 隔離單元 ❹ C4 電容 D2 發光二極體 D5 發光二極體 D8 二極體 DIM 調光訊號 EA 放大器 LI 電感 〇 Q2 電晶體開關 R7 電阻 U 比較器 \ U4 誤差放大器 U7A 反及閘 - V4 電源 VIN 輸入電壓 Vref 參考電壓 Vrefl 第一參考電壓 19 20093014718 200930147 283b Signal selector 29c Minimum duty cycle signal generator 30 LED module 32 Current detector 34 Voltage detector 34a First voltage divider 34b Second voltage divider 36 Isolation unit ❹ C4 Capacitor D2 Diode D5 LED Diode D8 Diode DIM Dimming Signal EA Amplifier LI Inductance 〇 Q2 Transistor Switch R7 Resistor U Comparator \ U4 Error Amplifier U7A Inverting Gate - V4 Power Supply VIN Input Voltage Vref Reference Voltage Vrefl First Reference voltage 19 200930147
Vref2 Vref3 第二參考電壓 第三參考電壓 〇 ❹ 20Vref2 Vref3 Second reference voltage Third reference voltage 〇 ❹ 20