200906046 九、發明說明： 【發明所屬之技術領域】 驅動式 本發明係有關一種返馳式轉換器，特別是具有 同步整流器之返馳式轉換器。 【先前技術】 傳統之返馬也式轉換器(flyback converter)主要利用變壓器以及 -極體作為整流器，又稱為二極體整流器，用以將電源之能量傳輸 料部負載電路。變壓器電路具有分離之—次側線圈(二 winding)及二次側線圈(secondary winding)，其中—次側線圈用以連 接外部電源，而二次側線圈係為-感應線圈，用以感應1次側線圈 之磁通量(magnetic flux)變化而生感應電壓，連接整流器(rectifier)形 成電力電路(power circuit) ’用以驅動外部負載電路(1〇ad)。200906046 IX. DESCRIPTION OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention relates to a flyback converter, and more particularly to a flyback converter having a synchronous rectifier. [Prior Art] The conventional flyback converter mainly uses a transformer and a pole body as a rectifier, which is also called a diode rectifier, for transmitting the energy of the power source to the load circuit of the material. The transformer circuit has a separate secondary winding (secondary winding) and a secondary winding (secondary winding), wherein the secondary side coil is used for connecting an external power source, and the secondary side coil is an induction coil for sensing once. The magnetic flux of the side coil changes to generate an induced voltage, and a rectifier is connected to form a power circuit 'to drive an external load circuit (1〇ad).
請參考第1圖，其所示為傳統返馳式轉換器之電路。變壓器 10具有相互分離的一次側線圈Lp及二次側線圈Ls，—次側線圈〔 用以連接外部電壓源(power source)，而二次側線圈Ls，經由電力電 路(power circuit)後，連接外部負載電路(1〇ad)。圖中一次側線圈4 及二次側線圈Ls上的黑點表示同極性(同時為正極或負極）。 P 一次側線圈Ls連接二極體D!以形成電力電路，其中二極體 ^以整流，又稱為二極體整流器。電力電路之—輸出端為電壓= 出端，另一端為接地端，於電壓輸出端及接地端之間跨接電容c。， 稱為負載電容(load capacitor)。 首先介紹外部電源的供電方式，其通常區分為連續導通模式 _tm_s conduction m〇de CCM)及不連續導通模式(di_如_s conduction mode，DCM)。連續導通模式僅為不連續導通模式之特 例’以下S兒明不連續導通模式。其中輪入電愿以週期性方式供電， 5 〇46 時間樑為 t ’其定義如下： •首先為開啟期間，記為τ0η (0 < t < τΜ1)，此期間内外部電 源施電壓V^VfHIGH)於一次側線圈Lp，一次側線圈Lp 儲能’通過一次側線圈Lp線圈之電流漸增至最大值，二 次側線圈Ls&電流。 2·接著為重置期間，記為Tr (Ton < t < T〇n +Tr)，此期間内外 部電源關閉，二次側線圈Ls釋能，通過二次側線線圈ls 之電流is由最大漸減至0 ’ 一次側線圈Lp受反射輸出電 壓(reflected output voltage)匕=-#j/。，其中 1^及 Ns 分別 一次側線圈Lp及二次側線圈Ls^線圈數，一次側線圈Lp 之電流形成於一次側電感及一次側線圈Lp的 封閉迴路中，通過一次側開關之電流7^^) = 0。 3.最後為延遲期間，記為Tdead =TS - Ton - Tr (UT； < t < Ts) ’其中Ts表示開關一周期之期間，此期間内外部電源 關閉(V产0)，二次側線圈^不再釋能，無電流通過一次側 線圈Lp及二次側線圈Ls。 當感應電流未降至〇(釋能未完全），下一個週期即開始，則稱 ‘、’、連續導通模式。配合第1圖，以下說明返馳式轉換器之作動原理。 、開啟期間内，一次側線圈Lp及二次側線圈“上標示黑點之端 點為高壓端，二極體〇1為反向偏壓，電力電路未導通，由負載電六 C〇提供外部負載電路之電壓V。。 奋 重置期間，一次側線圈Lp及一次側線圈Ls上標矛愛μ 不恙點之端點 為低壓端，二極體D丨為順向偏壓’電力電路導通，雷六 々員載電容 C。及外部負載電路。 延遲期間，一次側線圈Lp及二次側線圈Ls上之電壓為〇 一 極體D!為反向偏壓-V。關閉，由負載電容C。提供外部負栽命- 电路之電 200906046 壓v〇。 此種返馳式轉換n之缺點在於二極體整流祕導致嚴重的導 通損失―。♦為降低導通損失，—般採用同步整流器以 替代二極體整流H，例如，氧化金射導體場效應電晶體(_1 〇xide semiconductor field effect transistor，M〇s)常被用來實作同步整流 器’其實作電路請參考第2圖。 <比較第2圖與第1圖所示之返馳式轉換器的電路，其不同處在 於採用n-MOS電晶體(η型氧化金屬半導體場效應電晶體)Μ〗替代二 極體作為同步整流盗’但此種設計需用積體電路控制器 (c〇ntr〇ller)IC以控制n_M〇S電晶體Ml之導通。 另有相似的返馳式轉換器的設計，請參考第3圖，其與第2圖 電路之不同處在於n_M〇S電晶體Miit接於貞麟圈之接地端。第 3圖所示之返馳式轉換器稱為低壓端驅動返馳式轉換器(丨〇w dnvenflybackCOnverter)，而第2圖電路之返馳式轉換器稱為高壓端 驅動返馳式轉換器(high side driven flyback converter)。此類設計，因 利用積體電路控制器1C而增加了電路的複雜度及成本。 為降低導通損失、電路的複雜度及成本，利用不同的電路以製 造返驰式轉換器，仍有其需求。 【發明内容】 本發明之一目的係降低返馳式轉換器之導通損失，其利 用同步整流器以控制二次側電力線圈之導通。 本發明之另一目的係降低返驰式轉換器電路之複雜 度，其利用二次側驅動線圈連接一開關控制器，用以接收電 壓偵測電路之偵測訊號，開關控制器依據此偵測訊號控制開 關之輸出訊號，進而決定開啟或關閉同步整流器。 200906046 為達上述目的， 驰式轉換器之實施例 ，本發明提供一種具自驅式同步整流器之返 •J，其包含變壓器、二極體、電壓偵剩電 路、開關控制器、開關及同步整流器。變壓器包含一次側： 圈—_人側驅動線圈及二次側電力線圈。一次側線圈用以連 接外部電源。二次側電力線圈連接同步整流器構成電力電 路，電力電路之輸出端包含一接地端（低壓端），一端為電壓 輸出端（高壓端）’電壓輸出端及接地端間跨接輸出電容。二 次側驅動線圈串接二極體、開關控制器及開關以形成驅動電 路’開關控制器連接於電壓偵測電路以接收電壓訊號，其中 電壓情測電路用以偵測電力電路之電壓，並傳送電壓訊號給 開關控制器’用以控制開關，進而令開關開啟或關閉同步整 流器。 【實施方式】 以下實施例及配合圖式以闡明本發明之精神。 請參考第4圖，說明本發明一實施例之返馳式變壓器 (transformer) 100 電路，其包含一次側線圈（primary winding)Lp、二次側驅動線圈（secondary driving winding)Ld 及二次側電力線圈（secondary power winding)!^ ’其中一次側 線圈Lp用以連接外部電源Vi。 二次側電力線圈L!連接電力電路(Power circult)，電力 電路之輸出包含電壓輸出端V〇(高壓端）以及接地端（低壓Please refer to Figure 1, which shows the circuit of a conventional flyback converter. The transformer 10 has a primary side coil Lp and a secondary side coil Ls which are separated from each other, a secondary side coil (for connecting an external power source), and a secondary side coil Ls connected via a power circuit. External load circuit (1〇ad). The black dots on the primary side coil 4 and the secondary side coil Ls in the figure indicate the same polarity (simultaneously positive or negative). P The primary side coil Ls is connected to the diode D! to form a power circuit in which the diode is rectified, also called a diode rectifier. The output of the power circuit is voltage = output, and the other end is ground. The capacitor c is connected between the voltage output terminal and the ground terminal. , called the load capacitor. First, the power supply mode of the external power supply will be described, which is generally divided into a continuous conduction mode _tm_s conduction m〇de CCM) and a discontinuous conduction mode (di_ such as _s conduction mode, DCM). The continuous conduction mode is only a special case of the discontinuous conduction mode. Among them, the wheeled power is willing to supply power in a periodic manner, and the 5 〇46 time beam is t', which is defined as follows: • First, during the opening period, it is recorded as τ0η (0 < t < τΜ1), during which the external power supply voltage V^ VfHIGH) in the primary side coil Lp, the primary side coil Lp stores 'current through the primary side coil Lp coil gradually increases to the maximum value, the secondary side coil Ls & current. 2. Then, during the reset period, it is recorded as Tr (Ton < t < T〇n + Tr). During this period, the external power supply is turned off, the secondary side coil Ls is released, and the current through the secondary side coil ls is Maximum decreasing to 0 ' The primary side coil Lp is reflected output voltage 匕 = -#j/. , where 1^ and Ns are the number of coils of the primary side coil Lp and the secondary side coil Ls, respectively, and the current of the primary side coil Lp is formed in the closed loop of the primary side inductance and the primary side coil Lp, and the current through the primary side switch 7^ ^) = 0. 3. Finally, the delay period is recorded as Tdead = TS - Ton - Tr (UT; < t < Ts) 'where Ts represents the period of one cycle of the switch, during which the external power supply is turned off (V is 0), twice The side coils ^ are no longer released, and no current passes through the primary side coil Lp and the secondary side coil Ls. When the induced current does not fall to 〇 (release energy is not complete), the next cycle begins, then ‘,’, continuous conduction mode. With the first diagram, the operation principle of the flyback converter will be described below. During the opening period, the primary side coil Lp and the secondary side coil "the end point of the black dot is the high voltage end, the diode 〇1 is the reverse bias voltage, the power circuit is not turned on, and the external circuit is provided by the load battery. The voltage of the load circuit V. During the reset, the primary side coil Lp and the primary side coil Ls are marked with a spear. The end point of the untwisted point is the low voltage end, and the diode D丨 is the forward bias voltage. , Ray-Leader load capacitor C. and external load circuit. During the delay, the voltage on the primary side coil Lp and the secondary side coil Ls is the first pole D! is the reverse bias -V. Closed, by the load capacitance C. Provide external negative life - circuit power 200906046 pressure v 〇. The disadvantage of this flyback conversion n is that the diode rectification secret causes serious conduction loss - ♦ To reduce the conduction loss, the synchronous rectifier is used Instead of diode rectification H, for example, 氧化xide semiconductor field effect transistor (M〇s) is often used to implement a synchronous rectifier. See Figure 2 for a circuit. Compare the picture shown in Figure 2 and Figure 1 The circuit of the converter is different in that it uses an n-MOS transistor (n-type oxidized metal semiconductor field effect transistor) instead of a diode as a synchronous rectification thief. However, this design requires an integrated circuit controller ( C〇ntr〇ller) IC to control the conduction of n_M〇S transistor Ml. Another similar design of the flyback converter, please refer to Figure 3, which differs from the circuit of Figure 2 in the n_M〇S The crystal Miit is connected to the ground of the unicorn circle. The flyback converter shown in Fig. 3 is called the low voltage end drive return converter (丨〇w dnvenflybackCOnverter), and the second diagram circuit is the flyback converter. It is called high side driven flyback converter. This type of design increases the complexity and cost of the circuit by using the integrated circuit controller 1C. To reduce the conduction loss, the complexity of the circuit and There is still a need for a different circuit to manufacture a flyback converter. SUMMARY OF THE INVENTION One object of the present invention is to reduce the conduction loss of a flyback converter, which utilizes a synchronous rectifier to control a secondary power coil. Turn on. Another object of the present invention is to reduce the complexity of the flyback converter circuit. The secondary side driving coil is connected to a switch controller for receiving the detection signal of the voltage detecting circuit, and the switch controller detects the signal according to the detection. The signal controls the output signal of the switch, which in turn determines whether to turn the synchronous rectifier on or off. 200906046 In order to achieve the above object, an embodiment of the chirp converter, the present invention provides a self-driven synchronous rectifier, comprising a transformer and a diode Body, voltage detection circuit, switch controller, switch and synchronous rectifier. The transformer consists of the primary side: the ring - the human side drive coil and the secondary side power coil. The primary side coil is used to connect to an external power source. The secondary side power coil is connected to the synchronous rectifier to form a power circuit. The output end of the power circuit includes a ground terminal (low voltage terminal), and one end is a voltage output terminal (high voltage terminal). The voltage output terminal and the ground terminal are connected to the output capacitor. The secondary side driving coil is connected in series with the diode, the switch controller and the switch to form a driving circuit. The switching controller is connected to the voltage detecting circuit for receiving the voltage signal, wherein the voltage sensing circuit is configured to detect the voltage of the power circuit, and The voltage signal is sent to the switch controller to control the switch, which in turn causes the switch to turn the synchronous rectifier on or off. [Embodiment] The following embodiments and the accompanying drawings are intended to illustrate the spirit of the invention. Referring to FIG. 4, a flyback transformer 100 circuit according to an embodiment of the present invention includes a primary winding Lp, a secondary driving winding Ld, and a secondary side power line. Secondary power winding! ^ 'The primary side coil Lp is used to connect the external power source Vi. The secondary side power coil L! is connected to a power circuit (Power circult), and the output of the power circuit includes a voltage output terminal V〇 (high voltage terminal) and a ground terminal (low voltage)
路，分別用以接收偵測訊號及導 用以穩壓。二次側驅動綠® 電壓偵測電路500及電力電路 通或斷開電力電路。 200906046 電壓偵測電路500偵測電力電路之電壓，並傳送偵測訊 號給驅動電路’ 路再㈣此彳貞測魏決料通或 電力電路。 第5圖為根據本發明之一實施例說明一次側線圈Lp、二 次側驅動線® Ld、驅動電路以及電壓侧電路5GG之示意 圖。驅動電路包含二極體Dr開關控制器400及開關200Γ 開關控制器働具有輸人端彻、偵測端430及輸出端42〇， 開關具有第—電麗連接端22()、第二電壓連接端23〇及 訊號輸出端240。 一-人側驅動線圈Ld之第一端連接二極體D2之陽極，二 ^體〇2之陰極連接開關控制器彻之輸入端410,開關控制 器4〇〇之輪出端420連接開關2〇〇之第一電壓連接端22工〇 , 開關控制器400之偵測端43〇連接電壓谓測電路5〇〇。開關 200之第—電壓連接端23()連接二次側驅動線圈^之第二端 出端之同步整流益之流入端’而開關2〇0之訊號輸 “ 24G連接同步整流器之控制端（时未示），如此可導通 或關閉電力電路。另外，開關控制器彻之輸入端盘二 ::側驅，Ld第二端間連接電容。丨，用以穩壓並避免開 關控制器400浮接而受損害。 電約貞測電路遍可_電力電路上同步整流器之流入 知及化出端之_，本實施例中，其包含並聯之二電阻心、 R4 ,分別連接同步整流器的流入端及流出端之電壓（圖中未 H二^側驅動線圈^之第二端連接於同步整流器的流 二:故將電阻R3連接於二次側驅動線圈U之第二端，如 圚r所示。 200906046 給開關控制器400之偵測端430低電位之偵測訊號，而令開 關開關控制器400開啟開關200 ;當同步整流器300不導通 時，流入端320及流出端330則為開路，傳送給開關控制器 400之彳貞測端430高電位之偵測訊號’而令開關開關控制器 400關閉開關200。 第6圖為根據本發明之一實施例說明高壓端具自驅式同 步整流器之返驰式轉換器的一次側線圈Lp、二次側驅動線圈 Ld、驅動電路、二次側電力線圈Ll、電力電路及電壓偵測電 路500之示意圖。如圖所示，電力電路包含同步整流器300， 同步整流器300具有控制端310、流入端320及流出端330， 二次側電力線圈Li連接流入端320，流出端330連接至電壓 輸出端V〇。 驅動電路之開關200的訊號輸出端240連接同步整流器 300的控制端310,並將開關200的第二電壓連接端230連接 於同步整流器300的流入端320及二次側電力線圈之第二端。 電壓偵測電路500連接於開關控制器400之偵測端 430，其包含並聯之二電阻R3、R4，分別連接於電力電路之 同步整流器300之流入端320及流出端330。 根據上述實施例，於電源供電週期内，利用開關控制器 400的偵測端430的電壓變化，控制輸入端410及輸出端420 是否導通，藉以控制第一電壓連接端220與第二電壓連接端 230間的電壓變化，進而控制開關200的訊號輸出端240之 電位訊號。當訊號輸出端240連接於電力電路上之同步整流 器300時’電位訊號將可控制同步整流器300的流入端320 與流出端330是否導通。若同步整流器300之控制端310被 開啟且流入端320之電壓高於流出端330之電壓時，電流由 流入端320流向流出端330 ’二次側電力線圈L!經由同步整 200906046 流器300充電能於負載電容c。並驅動外部負載電路（圖上未 示）。若同步整流器300之控制端31〇被關閉時，流入端32〇 及流出端330為斷路，電力電路形成不導通，由負載電容c。 驅動外部負載電路。 第7圖為根據本發明之一實施例說明低壓端具自驅式同 步整流器之返驰式轉換器的一次側線圈Lp、二次側驅動線圈 Ld、驅動電路、二次側電力線圈Ll、電力電路及電壓偵測電 路500之示意圖。與高壓端具自驅式同步整流器之返驰式轉換 器的電力電路相較，低壓端具自驅式同步整流器之返馳式轉換 器的電力電路中的同步整流器300之流入端32〇串接於接地 端（低壓端）上，流出端330連接二次側電力線圈Li，控制端 310連接開關200的訊號輸出端240。本實施例之控制端的開 啟與關閉與南壓端具自驅式同步整流器之返驰式轉換器的電力 電路相同，於此不再贅述。 要說明的是，於一實施例中，利用N(P)型氧化金屬半導 體場效應電晶體(n/p-channel metal oxide semiconductor field effect transistor，n/p-MOS)、N ( P )型接面場效應半導體 (p/n-channel junction field effect transistor, ρ/η-JFET)或 PNP(NPN)雙極電晶體（pnp/npn bipolar junction transistor pnp/npn-BJT)實作同步整流器時’閘（基)極作為控制端31〇 / 並依據電晶體源（射）極與沒（集）極之特性分別定義流入端 320及流出端330。 例如，以η-MOS實作高（低）壓端具自驅式同步整流器之返 馳式轉換器之同步整流器，其控制端310、流入端32〇以= 流出端330分別為n-MOS電晶體之閘極、源極以及汲極，電 壓偵測電路係偵測n-MOS電晶體之源-汲極間的本體二極體 (body diode)之跨壓 ° 200906046 又如，利用PNP或NPN型雙極電晶體實作同步整流器， 因無如MOS電晶體之本體二極體之特性，需外接一二極體 提供跨壓，其連接方式係將二極體之陽極及陰極分別連接流 入端320及流出端330。如一實施例中，利用PNP型雙極電 晶體實作同步整流器時，以其基極、集極及射極作為控制端 310、流出端330及流入端320，於流入端320(射極）及流出 端330(集極）之間跨接二極體。 接著，第8圖所示為一低壓端具自驅式同步整流器之返驰 式轉換器實施例之電路圖。如圖所示，同步整流器300為一 n-MOS電晶體M2。 開關200以一互鎖型電路實作，互鎖型電路包含一 NPN 雙極電晶體Q!、PNP雙極電晶體Q2、二電阻&、R2。電晶 體Qi之射極連接電晶體Q2之射極且連接點定義為訊號輸出 端240。二電晶體Q〗、Q2之基極相接，電阻R!跨接在電晶 體Q1的集極與基極之間5且電阻R2跨接在電晶體Q2的集極 與基極之間。電晶體Qi及電晶體Q2之集極分別定義為第·一 電壓連接端220及第二電壓連接端230。 開關控制器400為一 PNP雙極電晶體Q3，其射極、基 極及集極分別被定義為輸入端410、偵測端430及輸出端420。 電壓偵測電路500包含並聯之二電阻R3、R4，並聯端連 接於開關控制器400之偵測端430(雙極電晶體Q3之基極）， 電阻R3、R4分別連接於同步整流器300之流入端320及流出 端330(n-MOS電晶體之源極與〉及極）。 根據電源供電之一週期内的電路之導通情況，電源供電 供電週期區分為開啟期間、重置期間以及延遲期間（定義已於 先前技術中描述）。當應用上述實施例時，其各區間的導通描 述如下： 12 200906046 開啟期間Τοη (0 < t < Ton). —極體D2受反向偏壓（reverse biased)而形成斷路，電容C〗施電壓於雙極電晶體q3之射極， 分壓電阻R4與R3施偏壓於其基極，因n_M〇s電晶體厘2之 本體二極體受反向偏壓（reverse biased)而形成斷路，使其没 極處於高電位’進而使雙極電晶體Q3之基極電位高於其射極 電位’雙極電晶體Q3之射極與基極受反向偏壓而關閉^開關 200之雙極電晶體仏亦關閉，n-MOS電晶體被關閉。即 使n-MO S電晶體Μ:之閘極積存電荷’也會很快的經由開關 200之電晶體Q2及電阻R_2而釋放’使n_M〇s電晶體m2之 閘源二極的跨壓降為0(Vgs=〇) ’而關閉n-MOS電晶體μ， 電力電路不導通，由輸出電容c。驅動外部負載電路之電Μ ν。 因此，在開啟期間Ton (0 < t < Tm)内，電流由n_M〇s電晶體地 之閘極流向電晶體Q2，即開關200之訊號輪出端240提供低電壓 訊號。 重置期間Tr (T〇n < t < Τ〇η +Tr):二極體J)2受順向偏壓 (forward biased)而導通，因n-MOS電晶體m2之本體二極體 受順向偏壓（forward biased)而導通，使其汲極處於低電位， 分壓電阻R4與R3施於雙極電晶體Qs的基極之電壓低於電容 I (^施於雙極電晶體&的射極之電壓，雙極電晶體a之射極 與基極受順向偏壓而導通，開關200之雙極電晶體q】亦導 通’電流由開關200之流入端220 ’經由電阻，開啟電曰 體Q!，進而在開關200之訊號輸出端240提供高電位，此高 電位使n-MOS電晶體M2被開啟，因而導通n_M〇s電晶體 M2的源極（流入端320)與汲極（流出端330)，電力電路形成通 路。因此，在重置期間Tr (Tm < t < Ton +Tr)内，電流由電晶體q - 流向n-MOS電晶體M2之閘極，即開關200之訊號輸出端2仙 提供高電壓訊號。 13 200906046 延遲期間 Tdead (Ton+Tr < t < Ton+Tr+Tdead):一 次側線圈 b、二 次側驅動線圈Ld以及二次側電力線圈Li不再釋能且無電流通 過，此時二極體D2無偏壓而形成斷路，n_M〇s電晶體μ〗被 關閉，電力電路不導通，由輸出電容C。驅動外部負載電路之電 壓V。。 另一實施例係利用PNP雙極電晶體實作同步整流器3〇〇時，需 外接二極體，以產生流入端320及流出端330之跨壓，其同步整流器 之實施例如第9圖所示。 高壓端具自驅式同步整流器之返馳式轉換器之原理同低壓 端具自驅式同步整流斋之返驰式轉換器，僅需注意同步整流器 之極性需連接正確，此不再贅述。 綜上所述，利用二次側驅動線圈形成一驅動電路，驅動 電路上之開關控制器受電壓偵測電路之偵測訊號以控制開 關，進而可開啟或關閉電力電路上之同步整流器，亦即利用 驅動電路開啟或關閉電力電路’如此完成具自驅式同步整流器 之返驰式轉換器。 以上所述之實施例僅係為說明本發明之技術思想及特 點，其目的在使熟習此項技藝之人士能夠瞭解本發明之内容 並據m當不能以之限定本發明之專利範圍，即大凡依 本發明所揭精㈣狀均等變化紐飾，㈣涵蓋在本 發明之專利範圍内。 【圖式簡單說明】 第1圖所示為習知技術之返馳式轉換器之電路圖。 第2圖所7F為白知技術之⑥壓端鶴返馳式轉換器之電路圖。 14 200906046 第3 _所示為習知技術之低壓端驅動返馳式轉換器 第4 电略圖。 _所示為本發明-實施例之具自驅式同步整流 益電路示意圖。 之返馳式轉換 第5 圖所示為本發明一實施例之具自驅式同步整流哭 器的驅動電路示意圖。 之魏式轉換 第6圖所示為本發明一實施例之高壓端具自驅式同步整流器之返 馳式轉換器電路示意圖。 、 第7圖所示為本發明一實施例之低壓端具自驅式同步整流器之返 驰式轉換器電路示意圖。 第8圖所示為本發明一實施例之低壓端具自驅式同步整流器之返 馳式轉換器電路圖。 第9圖所示為本發明一實施例之同步整流器，其中αΡΝΡ雙極電晶 體及二極體實作同步整流器。 【主要元件符號說明】 10 變壓器 D!、D2 二極體 Lp、Ls、La、L! 線圈 Co'Q 電容 Ri' R2Λ R3' R4 電阻 Qi、Q2、q3 雙極電晶體 M】、M2 MOS電晶體 V!、V0 電壓 15 200906046 IC 積體電路控制器 100 返驰式變壓器 200 開關 220,230 連接端 240 輸出端 300 同步整流器 310 控制端 320 流入端 330 流出端 400 開關控制器 410 輸入端 420 輸出端 430 偵測端 500 電壓偵測電路 16The roads are used to receive detection signals and to regulate voltage. The secondary side drives the Green® voltage detection circuit 500 and the power circuit to open or disconnect the power circuit. 200906046 The voltage detecting circuit 500 detects the voltage of the power circuit and transmits a detection signal to the driving circuit. (4) This is a test or a power circuit. Fig. 5 is a schematic view showing a primary side coil Lp, a secondary side drive line ® Ld, a drive circuit, and a voltage side circuit 5GG according to an embodiment of the present invention. The driving circuit comprises a diode Dr switch controller 400 and a switch 200. The switch controller has an input end, a detecting end 430 and an output end 42. The switch has a first electric connection end 22 () and a second voltage connection. Terminal 23 and signal output 240. The first end of the one-side driving coil Ld is connected to the anode of the diode D2, the cathode connecting the switch of the two body 〇2 is connected to the input end 410, and the wheel end 420 of the switch controller 4 is connected to the switch 2 The first voltage connection terminal 22 is configured, and the detection terminal 43 of the switch controller 400 is connected to the voltage pre-measure circuit 5〇〇. The first voltage connection end 23 of the switch 200 is connected to the synchronous output of the second end of the secondary side drive coil ^, and the signal of the switch 2〇0 is input. Not shown), this can turn on or off the power circuit. In addition, the switch controller is completely connected to the input disk 2:: side drive, Ld connects the capacitor between the second end. 丨, to stabilize the voltage and avoid the switch controller 400 floating In addition, in the embodiment, the parallel sense resistor and the R4 are respectively connected to the inflow end of the synchronous rectifier and the inductive output of the synchronous rectifier. The voltage at the outflow end (the second end of the drive coil ^ in the figure is connected to the flow 2 of the synchronous rectifier: so the resistor R3 is connected to the second end of the secondary side drive coil U, as shown by 圚r. 200906046 gives the detection signal 430 of the switch controller 400 a low potential detection signal, and causes the switch switch controller 400 to turn on the switch 200; when the synchronous rectifier 300 is not turned on, the inflow terminal 320 and the outflow terminal 330 are open and transmitted to The test of the switch controller 400 430 high potential detection signal 'and switch switch controller 400 turns off switch 200. Fig. 6 is a diagram showing a primary side coil Lp of a flyback converter of a high voltage end-drive self-driven synchronous rectifier according to an embodiment of the present invention. A schematic diagram of the secondary side drive coil Ld, the drive circuit, the secondary side power coil L1, the power circuit and the voltage detection circuit 500. As shown, the power circuit includes a synchronous rectifier 300 having a control terminal 310 and an inflow The terminal 320 and the outflow terminal 330, the secondary side power coil Li is connected to the inflow terminal 320, and the outflow terminal 330 is connected to the voltage output terminal V. The signal output terminal 240 of the switch 200 of the driving circuit is connected to the control terminal 310 of the synchronous rectifier 300, and The second voltage connection end 230 of the switch 200 is connected to the inflow end 320 of the synchronous rectifier 300 and the second end of the secondary side power coil. The voltage detection circuit 500 is connected to the detection end 430 of the switch controller 400, which includes parallel The two resistors R3 and R4 are respectively connected to the inflow terminal 320 and the outflow terminal 330 of the synchronous rectifier 300 of the power circuit. According to the above embodiment, during the power supply cycle, the second resistors are used. Turning off the voltage change of the detecting end 430 of the controller 400, controlling whether the input terminal 410 and the output terminal 420 are turned on, thereby controlling the voltage change between the first voltage connection terminal 220 and the second voltage connection terminal 230, thereby controlling the signal of the switch 200. The potential signal of the output terminal 240. When the signal output terminal 240 is connected to the synchronous rectifier 300 on the power circuit, the 'potential signal> can control whether the inflow terminal 320 and the outflow terminal 330 of the synchronous rectifier 300 are turned on. If the control terminal 310 of the synchronous rectifier 300 When the voltage of the inflow terminal 320 is turned on and the voltage of the inflow terminal 320 is higher than the voltage of the outflow terminal 330, the current flows from the inflow terminal 320 to the outflow terminal 330 'the secondary side power coil L! The current can be charged to the load capacitance c via the synchronous 200906046 flow device 300. And drive the external load circuit (not shown). If the control terminal 31 of the synchronous rectifier 300 is turned off, the inflow terminal 32 and the outflow terminal 330 are open, and the power circuit is not turned on, and the load capacitance c is obtained. Drive the external load circuit. Figure 7 is a diagram showing a primary side coil Lp, a secondary side drive coil Ld, a drive circuit, a secondary side power coil L1, and a power of a flyback converter of a low voltage end self-driven synchronous rectifier according to an embodiment of the present invention. A schematic diagram of the circuit and voltage detection circuit 500. Compared with the power circuit of the flyback converter of the high voltage end self-driven synchronous rectifier, the inflow terminal 32 of the synchronous rectifier 300 in the power circuit of the flyback converter with the low voltage end of the self-driven synchronous rectifier is connected in series On the ground end (low voltage end), the outflow end 330 is connected to the secondary side power coil Li, and the control end 310 is connected to the signal output end 240 of the switch 200. The opening and closing of the control terminal of this embodiment is the same as that of the flyback converter of the self-driven synchronous rectifier at the south voltage terminal, and will not be described herein. It should be noted that, in an embodiment, an N/P-channel metal oxide semiconductor field effect transistor (n/p-MOS) and an N (P) type are used. Surface field effect semiconductor (p/n-channel junction field effect transistor, ρ/η-JFET) or PNP (NPN) bipolar transistor (pnp/npn bipolar junction transistor pnp/npn-BJT) is implemented as a synchronous rectifier The (base) pole serves as the control terminal 31〇/ and defines the inflow terminal 320 and the outflow terminal 330, respectively, depending on the characteristics of the transistor source (emission) and the (set) pole. For example, a synchronous rectifier of a flyback converter with a self-driven synchronous rectifier with a high (low) voltage terminal implemented by η-MOS has a control terminal 310, an inflow terminal 32〇, and an outflow terminal 330 respectively n-MOS. The gate, source and drain of the crystal, the voltage detection circuit detects the source voltage of the source-drain between the source of the n-MOS transistor. 200906046 Again, using PNP or NPN The bipolar transistor is implemented as a synchronous rectifier. Because it has no characteristics of the body diode of the MOS transistor, an external diode is required to provide a voltage across the pole. The connection method is to connect the anode and the cathode of the diode to the inflow end respectively. 320 and the outflow end 330. In an embodiment, when the PNP-type bipolar transistor is used as the synchronous rectifier, the base, the collector and the emitter are used as the control terminal 310, the outflow terminal 330 and the inflow terminal 320, and the inflow terminal 320 (emitter) and A diode is bridged between the outflow terminals 330 (collectors). Next, Fig. 8 is a circuit diagram showing an embodiment of a flyback converter of a low voltage end self-driven synchronous rectifier. As shown, the synchronous rectifier 300 is an n-MOS transistor M2. The switch 200 is implemented as an interlocking type circuit comprising an NPN bipolar transistor Q!, a PNP bipolar transistor Q2, a second resistor & R2. The emitter of the electric crystal Qi is connected to the emitter of the transistor Q2 and the connection point is defined as the signal output terminal 240. The bases of the two transistors Q and Q2 are connected, and the resistor R! is connected between the collector and the base of the electromorph Q1 and the resistor R2 is connected between the collector and the base of the transistor Q2. The collectors of the transistor Qi and the transistor Q2 are defined as a first voltage connection terminal 220 and a second voltage connection terminal 230, respectively. The switch controller 400 is a PNP bipolar transistor Q3 whose emitter, base and collector are defined as an input terminal 410, a detection terminal 430 and an output terminal 420, respectively. The voltage detecting circuit 500 includes two parallel resistors R3 and R4 connected to the detecting end 430 of the switch controller 400 (the base of the bipolar transistor Q3), and the resistors R3 and R4 are respectively connected to the inflow of the synchronous rectifier 300. Terminal 320 and efflux terminal 330 (source and 〉 and pole of n-MOS transistor). The power supply power cycle is divided into an on period, a reset period, and a delay period (as defined in the prior art), depending on the conduction of the circuit during one cycle of the power supply. When the above embodiment is applied, the conduction of each section is described as follows: 12 200906046 Turn-on period Τοη (0 < t < Ton). - Polar body D2 is reverse biased to form an open circuit, capacitance C The voltage is applied to the emitter of the bipolar transistor q3, and the voltage dividing resistors R4 and R3 are biased to the base thereof, since the body diode of the n_M〇s transistor PCT 2 is reverse biased. Open circuit, so that the pole is at a high potential' and then the base potential of the bipolar transistor Q3 is higher than its emitter potential'. The emitter and base of the bipolar transistor Q3 are reverse biased and turned off. The bipolar transistor turns off and the n-MOS transistor is turned off. Even if the n-MO S transistor Μ: the gate charge charge 'will be quickly released via the transistor Q2 of the switch 200 and the resistor R_2', the voltage across the gate of the n_M〇s transistor m2 is reduced to 0 (Vgs=〇) 'When the n-MOS transistor μ is turned off, the power circuit is not turned on, and the output capacitor c is used. Drive the external load circuit ν. Therefore, during the turn-on period Ton (0 < t < Tm), the current flows from the gate of the n_M〇s transistor to the transistor Q2, i.e., the signal wheel output terminal 240 of the switch 200 provides a low voltage signal. Reset period Tr (T〇n < t < Τ〇η + Tr): diode J) 2 is turned on by forward biased, due to the body diode of n-MOS transistor m2 Conducted by forward biased conduction, so that its drain is at a low potential, and the voltages of the voltage divider resistors R4 and R3 applied to the base of the bipolar transistor Qs are lower than the capacitance I (^ applied to the bipolar transistor) The emitter voltage of & the emitter and base of the bipolar transistor a are turned on by the forward bias, and the bipolar transistor of the switch 200 is also turned on. The current is passed through the inflow terminal 220 of the switch 200. Turning on the electrical body Q!, and then providing a high potential at the signal output terminal 240 of the switch 200, this high potential causes the n-MOS transistor M2 to be turned on, thereby turning on the source of the n_M〇s transistor M2 (inflow terminal 320) With the drain (outflow terminal 330), the power circuit forms a path. Therefore, in the reset period Tr (Tm < t < Ton + Tr), the current flows from the transistor q - to the gate of the n-MOS transistor M2 , that is, the signal output terminal of the switch 200 provides a high voltage signal. 13 200906046 Delay period Tdead (Ton+Tr < t < Ton+Tr+Tdead): primary side coil b, twice The side drive coil Ld and the secondary side power coil Li are no longer discharged and no current flows. At this time, the diode D2 is unbiased to form an open circuit, the n_M〇s transistor μ is turned off, and the power circuit is not turned on. Capacitor C. Driving the voltage of the external load circuit V. Another embodiment uses a PNP bipolar transistor to implement a synchronous rectifier 3〇〇, which requires an external diode to generate a voltage across the inflow terminal 320 and the outflow terminal 330. The implementation of the synchronous rectifier is shown in Fig. 9. The principle of the flyback converter with the self-driven synchronous rectifier at the high voltage end and the self-driven synchronous rectification of the low voltage end, only need to pay attention to the synchronization. The polarity of the rectifier needs to be connected correctly, and will not be described again. In summary, the secondary side drive coil is used to form a driving circuit, and the switch controller on the driving circuit is controlled by the voltage detecting circuit to control the switch, and then Turning on or off the synchronous rectifier on the power circuit, that is, using the drive circuit to turn the power circuit on or off. This completes the flyback converter with the self-driven synchronous rectifier. The invention is only intended to illustrate the technical idea and the features of the present invention, and it is intended to enable those skilled in the art to understand the contents of the present invention and to limit the scope of the invention according to the invention. (4) Equally changing the decoration, (4) is covered by the patent of the present invention. [Simplified description of the drawing] Fig. 1 is a circuit diagram of a flyback converter of the prior art. The circuit diagram of the 6th crane crane return converter. 14 200906046 3rd _ shows the low voltage side drive flyback converter of the prior art. _ is a schematic diagram of a self-driven synchronous rectification circuit of the present invention. The flyback conversion Fig. 5 is a schematic diagram showing a drive circuit of a self-driven synchronous rectification crying device according to an embodiment of the present invention. Wei-type conversion Fig. 6 is a circuit diagram showing a fly-back converter of a high-voltage end-drive self-driven synchronous rectifier according to an embodiment of the present invention. FIG. 7 is a schematic diagram showing a circuit of a flyback converter of a low voltage end-drive self-driven synchronous rectifier according to an embodiment of the invention. Figure 8 is a circuit diagram showing a flyback converter of a low voltage end-drive self-driven synchronous rectifier according to an embodiment of the present invention. Fig. 9 is a diagram showing a synchronous rectifier according to an embodiment of the present invention, wherein an αΡΝΡ bipolar transistor and a diode are implemented as a synchronous rectifier. [Main component symbol description] 10 Transformer D!, D2 diode Lp, Ls, La, L! Coil Co'Q Capacitor Ri' R2Λ R3' R4 Resistor Qi, Q2, q3 Bipolar transistor M], M2 MOS Crystal V!, V0 Voltage 15 200906046 IC Integrated Circuit Controller 100 Flyback Transformer 200 Switch 220, 230 Terminal 240 Output 300 Synchronous Rectifier 310 Control Terminal 320 Inflow Terminal 330 Outflow Terminal 400 Switching Controller 410 Input Terminal 420 Output Terminal 430 Detection terminal 500 voltage detection circuit 16