TWI646770B - Synchronous rectifier - Google Patents
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Abstract
本發明係揭露一種同步整流裝置，其係連接一電源供應器之一變壓器之二次側與一輸出電容，同步整流裝置包含一整流開關、一壓控開關器與一整流控制器。整流開關連接於二次側與輸出電容之間。壓控開關器具有一分壓電容，壓控開關器連接二次側，以接收二次側產生之二次側電壓。整流控制器連接壓控開關器與整流開關。在二次側電壓上升至低於第一電壓值之切換電壓值時，整流控制器控制整流開關為非導通，而在整流開關為非導通後，壓控開關器為非導通，以利用分壓電容接收二次側電壓，並順利實現同步整流。The invention discloses a synchronous rectifying device which is connected to a secondary side of a transformer of a power supply and an output capacitor. The synchronous rectifying device comprises a rectifying switch, a voltage controlled switch and a rectifying controller. The rectifier switch is connected between the secondary side and the output capacitor. The voltage control switch has a voltage dividing capacitor, and the voltage control switch is connected to the secondary side to receive the secondary side voltage generated by the secondary side. The rectifier controller is connected to the voltage control switch and the rectifier switch. When the secondary side voltage rises to a switching voltage value lower than the first voltage value, the rectifier controller controls the rectifier switch to be non-conductive, and after the rectifier switch is non-conductive, the voltage control switch is non-conductive to utilize the voltage division. The capacitor receives the secondary side voltage and smoothly realizes synchronous rectification.
Description
本發明係關於一種同步整流裝置，且特別是指用於電源供應器之同步整流裝置。The present invention relates to a synchronous rectifying device, and more particularly to a synchronous rectifying device for a power supply.
在市面上，電源供應器能輸出高電壓與定電流。因為此電源供應器之需求功率小，所以輸出電流亦小，且變壓器之二次側之同步整流器係採用二極體實現。當燈具之應用範圍愈廣，則功率要求也愈高。若在二次側仍舊使用二極體來實現同步整流器，將會造成損失過大、效率差、散熱不易、輸出電容之壽命下降且電源供應器之保固日期變短。On the market, the power supply can output high voltage and constant current. Because the power demand of this power supply is small, the output current is also small, and the synchronous rectifier on the secondary side of the transformer is implemented by a diode. When the application range of the luminaire is wider, the power requirement is also higher. If the diode is still used to realize the synchronous rectifier on the secondary side, the loss will be too large, the efficiency will be poor, the heat dissipation will be difficult, the life of the output capacitor will be lowered, and the warranty date of the power supply will be shortened.
如第1圖所示，其係說明負載10與電源供應器中二極體12、變壓器14之二次側與輸出電容16之連接關係，其中每一二極體12係作為一同步整流器。然而，因為二極體12之導通損失極大，且產生過多熱量，故如第2圖所示，將兩並聯之二極體12組成為一同步整流器，以試圖分散熱量。當二極體12導通後，二極體12之導通電壓並非與導通電流呈正比關係。且導通電流愈大，導通電壓僅有小幅度變化。因此，第2圖之二極體12僅能分散熱，但電源供應器之輸出效率依然無法有效提升。此外，會有電流分配不均的問題。為了減少導通損失，連接一同步整流電路18於二次側，如第3圖所示。同步整流電路18包含一N通道金氧半場效電晶體20、一第一電阻22、一第二電阻24、一二極體26、一齊納(Zener)二極體28、一電容30與一積體電路(IC)32，其中以N通道金氧半場效電晶體20直接連接二次側。當電源供應器輸出上百伏特之電壓時，跨在第一電阻22上的高電壓會造成極大的損失。若增加第一電阻22之電阻值，則會使積體電路32難以偵測到N通道金氧半場效電晶體20之汲極電壓。As shown in FIG. 1, the connection relationship between the load 10 and the diode 12 in the power supply, the secondary side of the transformer 14, and the output capacitor 16 is illustrated, wherein each of the diodes 12 functions as a synchronous rectifier. However, since the conduction loss of the diode 12 is extremely large and excessive heat is generated, as shown in Fig. 2, the two parallel diodes 12 are combined into a synchronous rectifier in an attempt to dissipate heat. When the diode 12 is turned on, the turn-on voltage of the diode 12 is not proportional to the on current. And the larger the on-current, the small change in the on-voltage. Therefore, the diode 12 of Fig. 2 can only dissipate heat, but the output efficiency of the power supply cannot be effectively improved. In addition, there is a problem of uneven current distribution. In order to reduce the conduction loss, a synchronous rectification circuit 18 is connected to the secondary side as shown in FIG. The synchronous rectification circuit 18 includes an N-channel MOS field-effect transistor 20, a first resistor 22, a second resistor 24, a diode 26, a Zener diode 28, a capacitor 30 and a product. The body circuit (IC) 32 in which the N-channel MOS field-effect transistor 20 is directly connected to the secondary side. When the power supply outputs a voltage of one hundred volts, the high voltage across the first resistor 22 causes a great loss. Increasing the resistance value of the first resistor 22 makes it difficult for the integrated circuit 32 to detect the drain voltage of the N-channel MOS field-effect transistor 20.
因此，本發明係在針對上述的困擾，提出一種同步整流裝置，以解決習知所產生的問題。Accordingly, the present invention has been made in view of the above-mentioned problems, and proposes a synchronous rectifying device to solve the problems caused by the prior art.
本發明的主要目的，在於提供一種同步整流裝置，其係利用具有分壓電容之壓控開關器偵測二次側電壓，以大幅提升輸出效率、降低損失、增加電容可靠度與產品保固年限，並達到精準同步整流。The main object of the present invention is to provide a synchronous rectifying device which uses a voltage-controlled switch with a voltage dividing capacitor to detect the secondary side voltage, thereby greatly improving output efficiency, reducing loss, increasing capacitance reliability and product warranty period. And achieve precise synchronous rectification.
為達上述目的，本發明提供一種同步整流裝置，其係連接一電源供應器之一變壓器之二次側與一輸出電容，同步整流裝置包含一整流開關、一壓控開關器與一整流控制器。整流開關連接於二次側與輸出電容之間。壓控開關器具有一分壓電容，壓控開關器連接二次側，以接收二次側產生之二次側電壓。整流控制器連接壓控開關器與整流開關。在二次側電壓上升至低於第一電壓值之切換電壓值時，整流控制器控制整流開關為非導通，而在整流開關為非導通後，壓控開關器為非導通，分壓電容接收二次側電壓，且二次側電壓繼續上升至第一電壓值為止。To achieve the above objective, the present invention provides a synchronous rectifying device connected to a secondary side of a transformer of a power supply and an output capacitor, the synchronous rectifying device comprising a rectifying switch, a voltage controlled switch and a rectifying controller . The rectifier switch is connected between the secondary side and the output capacitor. The voltage control switch has a voltage dividing capacitor, and the voltage control switch is connected to the secondary side to receive the secondary side voltage generated by the secondary side. The rectifier controller is connected to the voltage control switch and the rectifier switch. When the secondary side voltage rises to a switching voltage value lower than the first voltage value, the rectifier controller controls the rectifier switch to be non-conducting, and after the rectifier switch is non-conducting, the voltage control switch is non-conducting, and the voltage dividing capacitor receives The secondary side voltage, and the secondary side voltage continues to rise to the first voltage value.
在本發明之一實施例中，在二次側電壓下降至小於切換電壓值之第二電壓值時，壓控開關器呈現導通狀態，且整流控制器透過壓控開關器偵測第二電壓值，以導通整流開關。In an embodiment of the invention, when the voltage on the secondary side drops to a second voltage value that is less than the value of the switching voltage, the voltage control switch is in an on state, and the rectifier controller detects the second voltage value through the voltage control switch. To turn on the rectifier switch.
在本發明之一實施例中，壓控開關器為一N通道金氧半場效電晶體，其汲極連接整流開關與二次側，以接收二次側電壓，N通道金氧半場效電晶體之閘極連接一直流電壓源，以接收直流電壓源之直流電壓值。直流電壓值小於或等於第一電壓值，直流電壓值大於第二電壓值。N通道金氧半場效電晶體之源極連接整流控制器，且N通道金氧半場效電晶體之寄生源汲電容作為分壓電容。在整流開關為非導通後，N通道金氧半場效電晶體為非導通。在二次側電壓為第二電壓值時，N通道金氧半場效電晶體呈現導通狀態，且整流控制器偵測第二電壓值。 In an embodiment of the invention, the voltage controlled switch is an N-channel gold-oxygen half-field effect transistor, the drain is connected to the rectifier switch and the secondary side to receive the secondary side voltage, and the N-channel gold-oxygen half-field effect transistor The gate is connected to the DC voltage source to receive the DC voltage value of the DC voltage source. The DC voltage value is less than or equal to the first voltage value, and the DC voltage value is greater than the second voltage value. The source of the N-channel MOS half-effect transistor is connected to the rectifier controller, and the parasitic source tantalum capacitor of the N-channel MOS field-effect transistor is used as the voltage dividing capacitor. After the rectifier switch is non-conducting, the N-channel gold-oxygen half field effect transistor is non-conducting. When the secondary side voltage is the second voltage value, the N-channel MOS half-field effect transistor is in an on state, and the rectifier controller detects the second voltage value.
在本發明之一實施例中，壓控開關器更包含一輔助電容、一N通道金氧半場效電晶體與一二極體。N通道金氧半場效電晶體之汲極連接整流開關與二次側，以接收二次側電壓，N通道金氧半場效電晶體之閘極連接一直流電壓源，以接收直流電壓源之直流電壓值。直流電壓值小於或等於第一電壓值，直流電壓值大於第二電壓值，N通道金氧半場效電晶體之源極連接整流控制器，且輔助電容連接於汲極與源極之間，N通道金氧半場效電晶體之寄生源汲電容與輔助電容形成分壓電容。在整流開關為非導通後，N通道金氧半場效電晶體為非導通。二極體之陽極連接源極，二極體之陰極連接汲極，在二次側電壓為第二電壓值時，N通道金氧半場效電晶體呈現導通狀態，且整流控制器偵測第二電壓值。 In an embodiment of the invention, the voltage controlled switch further includes an auxiliary capacitor, an N-channel MOSFET, and a diode. The drain of the N-channel MOSFET is connected to the secondary side to receive the secondary side voltage, and the gate of the N-channel MOSFET is connected to the DC voltage source to receive the DC voltage of the DC voltage source. Voltage value. The DC voltage value is less than or equal to the first voltage value, and the DC voltage value is greater than the second voltage value. The source of the N-channel MOS field-effect transistor is connected to the rectifier controller, and the auxiliary capacitor is connected between the drain and the source, N The parasitic source of the channel gold oxide half field effect transistor and the auxiliary capacitor form a voltage dividing capacitor. After the rectifier switch is non-conducting, the N-channel gold-oxygen half field effect transistor is non-conducting. The anode of the diode is connected to the source, and the cathode of the diode is connected to the drain. When the voltage of the secondary side is the second voltage value, the N-channel MOS half-effect transistor is turned on, and the rectifier controller detects the second. Voltage value.
在本發明之一實施例中，壓控開關器更包含一NPN雙載子接面電晶體與一二極體。NPN雙載子接面電晶體之射極連接整流開關與二次側，以接收二次側電壓，NPN雙載子接面電晶體之基極連接一直流電壓源，以接收直流電壓源之直流電壓值。直流電壓值小於或等於第一電壓值，直流電壓值大於第二電壓值，分壓電容連接於NPN雙載子接面電晶體之射極與集極間，集極連接整流控制器。在整流開關為非導通後，NPN雙載子接面電晶體為非導通。二極體之陽極連接集極，二極體之陰極連接射極。在二次側電壓為第二電壓值時，NPN雙載子接面電晶體呈現導通狀態，且整流控制器偵測第二電壓值。 In an embodiment of the invention, the voltage controlled switch further includes an NPN bipolar junction transistor and a diode. The emitter of the NPN bipolar junction transistor is connected to the rectifying switch and the secondary side to receive the secondary side voltage, and the base of the NPN bipolar junction transistor is connected to the DC voltage source to receive the DC voltage of the DC voltage source. Voltage value. The DC voltage value is less than or equal to the first voltage value, the DC voltage value is greater than the second voltage value, the voltage dividing capacitor is connected between the emitter and the collector of the NPN bipolar junction transistor, and the collector is connected to the rectifier controller. After the rectifier switch is non-conducting, the NPN bipolar junction transistor is non-conducting. The anode of the diode is connected to the collector, and the cathode of the diode is connected to the emitter. When the secondary side voltage is the second voltage value, the NPN bipolar junction transistor exhibits an on state, and the rectifier controller detects the second voltage value.
在本發明之一實施例中，同步整流裝置更包含一暫態電壓抑制器(TVS)，其一端連接整流控制器與壓控開關器，另一端接地，暫態電壓抑制器穩定整流控制器所偵測之電壓。 In an embodiment of the invention, the synchronous rectification device further comprises a transient voltage suppressor (TVS), one end of which is connected to the rectification controller and the voltage control switch, and the other end is grounded, and the transient voltage suppressor stabilizes the rectifier controller The voltage detected.
在本發明之一實施例中，同步整流裝置更包含一齊納(Zener)二極體，其一端連接整流控制器與壓控開關器，另一端接地，暫態電壓抑制器穩定整流控制器所偵測之電壓。 In an embodiment of the invention, the synchronous rectifying device further comprises a Zener diode, one end of which is connected to the rectifying controller and the voltage controlled switch, and the other end is grounded, and the transient voltage suppressor stabilizes the rectifying controller Measured voltage.
在本發明之一實施例中，直流電壓源係由電源供應器之輔助電源提供。 In one embodiment of the invention, the DC voltage source is provided by an auxiliary power source of the power supply.
在本發明之一實施例中，整流開關為N通道金氧半場效電晶體或P通道金氧半場效電晶體。 In an embodiment of the invention, the rectifier switch is an N-channel MOSFET or a P-channel MOS field effect transistor.
在本發明之一實施例中，同步整流裝置更包含一第一電阻與一第二電阻。第一電阻連接於整流控制器與整流開關之間，第二電阻連接於整流控制器與壓控開關器之間，整流控制器透過第二電阻偵測第二電壓值。 In an embodiment of the invention, the synchronous rectifying device further includes a first resistor and a second resistor. The first resistor is connected between the rectifier controller and the rectifier switch, the second resistor is connected between the rectifier controller and the voltage control switch, and the rectifier controller detects the second voltage value through the second resistor.
茲為使 貴審查委員對本發明的結構特徵及所達成的功效更有進一步的瞭解與認識，謹佐以較佳的實施例圖及配合詳細的說明，說明如後： In order to give your reviewers a better understanding and understanding of the structural features and efficacies of the present invention, the following is a description of the preferred embodiment and the detailed description.
10‧‧‧負載 10‧‧‧ load
12‧‧‧二極體 12‧‧‧ diode
14‧‧‧變壓器 14‧‧‧Transformers
16‧‧‧輸出電容 16‧‧‧Output capacitor
18‧‧‧同步整流電路 18‧‧‧Synchronous rectifier circuit
20‧‧‧N通道金氧半場效電晶體 20‧‧‧N-channel MOS half-field effect transistor
22‧‧‧第一電阻 22‧‧‧First resistance
24‧‧‧第二電阻 24‧‧‧second resistance
26‧‧‧二極體 26‧‧‧ diode
28‧‧‧齊納二極體 28‧‧‧Zina diode
30‧‧‧電容 30‧‧‧ Capacitance
32‧‧‧積體電路 32‧‧‧ integrated circuit
34‧‧‧同步整流裝置 34‧‧‧Synchronous rectifier
36‧‧‧變壓器 36‧‧‧Transformers
38‧‧‧輸出電容 38‧‧‧Output capacitor
40‧‧‧負載 40‧‧‧ load
42‧‧‧整流開關 42‧‧‧Rectifier switch
44‧‧‧壓控開關器 44‧‧‧Variable control switch
45‧‧‧分壓電容 45‧‧‧voltage capacitor
46‧‧‧整流控制器 46‧‧‧Rectifier Controller
48‧‧‧暫態電壓抑制器 48‧‧‧Transient voltage suppressor
50‧‧‧第一電阻 50‧‧‧First resistance
52‧‧‧第二電阻 52‧‧‧second resistance
54‧‧‧N通道金氧半場效電晶體 54‧‧‧N-channel MOS half-field effect transistor
56‧‧‧直流電壓源 56‧‧‧DC voltage source
58‧‧‧寄生源汲電容 58‧‧‧ Parasitic source tantalum capacitor
60‧‧‧寄生基汲二極體 60‧‧‧ Parasitic bismuth diode
62‧‧‧輔助電容 62‧‧‧Auxiliary capacitor
64‧‧‧二極體 64‧‧‧ diode
66‧‧‧NPN雙載子接面電晶體 66‧‧‧NPN double carrier junction transistor
第1圖為先前技術之變壓器、二顆二極體、輸出電容與負載之電路示意圖。 Figure 1 is a schematic diagram of a prior art transformer, two diodes, an output capacitor and a load.
第2圖為先前技術之變壓器、四顆二極體、輸出電容與負載之電路示意圖。 Figure 2 is a schematic diagram of a prior art transformer, four diodes, output capacitors and loads.
第3圖為先前技術之變壓器與同步整流電路之電路示意圖。 Figure 3 is a circuit diagram of a prior art transformer and synchronous rectification circuit.
第4圖為本發明之同步整流裝置之第一實施例之電路示意圖。 Fig. 4 is a circuit diagram showing the first embodiment of the synchronous rectifying device of the present invention.
第5圖為本發明之同步整流裝置之第二實施例之電路示意圖。 Fig. 5 is a circuit diagram showing a second embodiment of the synchronous rectifying device of the present invention.
第6圖為本發明之同步整流裝置之第三實施例之電路示意圖。 Figure 6 is a circuit diagram showing a third embodiment of the synchronous rectifying device of the present invention.
本發明之實施例將藉由下文配合相關圖式進一步加以解說。盡可能的，於圖式與說明書中，相同標號係代表相同或相似構件。於圖式中，基於簡化與方便標示，形狀與厚度可能經過誇大表示。可以理解的是，未特別顯示於圖式中或描述於說明書中之元件，為所屬技術領域中具有通常技術者所知之形態。本領域之通常技術者可依據本發明之內容而進行多種之改變與修改。 Embodiments of the invention will be further illustrated below in conjunction with the associated drawings. Wherever possible, the same reference numerals in the drawings In the drawings, shapes and thicknesses may be exaggerated based on simplification and convenient labeling. It is to be understood that the elements not specifically shown in the drawings or described in the specification are those of ordinary skill in the art. A variety of changes and modifications can be made by those skilled in the art in light of the present invention.
以下請參閱第4圖。以下介紹本發明之同步整流裝置34之第一實施例，同步整流裝置34連接一電源供應器之一變壓器36之二次側與一輸出電容38，輸出電容38與一負載40並聯，且輸出電容38之一端連接二次側，另一端接地。電源供應器為順向式(Forward)、反馳式(Flyback)或者諧振式電源供應器，但不以此為限。電源供應器具有一主電源與一輔助電源，輔助電源之電壓小於主電源之電壓。同步整流裝置34包含一整流開關42、一壓控開關器44、一整流控制器46、一暫態電壓抑制器(TVS)48、一第一電阻50與一第二電阻52，其中暫態電壓抑制器48例如為齊納(Zener)二極體或二極體串列(diode-string)，整流開關42為N通道金氧半場效電晶體或P通道金氧半場效電晶體。在此第一實施例中，暫態電壓抑制器48以齊納二極體為例，整流開關42以N通道金氧半場效電晶體為例。整流開關42連接於二次側與輸出電容38之間。壓控開關器44具有一分壓電容45，壓控開關器44連接二次側，以接收二次側產生之二次側電壓 VS。整流控制器46連接壓控開關器44與整流開關42。在二次側電壓VS上升至低於第一電壓值之切換電壓值時，整流控制器46控制整流開關42為非導通，而在整流開關42為非導通後，壓控開關器44為非導通，分壓電容45接收二次側電壓VS，二次側電壓VS繼續上升至第一電壓值為止。分壓電容45的容值可以依照需求調整，原則上要能夠承受第一電壓值。此第一電壓值為二次側電壓VS之最大值。在二次側電壓VS下降至小於切換電壓值之第二電壓值時，壓控開關器44呈現導通狀態，且整流控制器46透過壓控開關器44偵測第二電壓值，以導通整流開關42。此暫態電壓抑制器48之一端連接整流控制器46與壓控開關器44，另一端接地，暫態電壓抑制器48穩定整流控制器46所偵測之電壓。因此第一電壓值會大於暫態電壓抑制器48之箝位電壓。第一電阻50連接於整流控制器46與整流開關42之間，第二電阻52連接於整流控制器46與壓控開關器44之間，整流控制器46透過第二電阻52偵測第二電壓值。 Please refer to Figure 4 below. The first embodiment of the synchronous rectifying device 34 of the present invention is described below. The synchronous rectifying device 34 is connected to a secondary side of a transformer 36 of a power supply and an output capacitor 38. The output capacitor 38 is connected in parallel with a load 40, and the output capacitor is output. One end of 38 is connected to the secondary side, and the other end is grounded. The power supply is a forward, flyback or resonant power supply, but not limited to this. The power supply has a main power supply and an auxiliary power supply, and the voltage of the auxiliary power supply is lower than the voltage of the main power supply. The synchronous rectification device 34 includes a rectification switch 42, a voltage control switch 44, a rectification controller 46, a transient voltage suppressor (TVS) 48, a first resistor 50 and a second resistor 52, wherein the transient voltage The suppressor 48 is, for example, a Zener diode or a diode-string, and the rectifier switch 42 is an N-channel MOS field effect transistor or a P-channel MOS field effect transistor. In the first embodiment, the transient voltage suppressor 48 is exemplified by a Zener diode, and the rectifier switch 42 is exemplified by an N-channel MOSFET. The rectifier switch 42 is connected between the secondary side and the output capacitor 38. The voltage control switch 44 has a voltage dividing capacitor 45, and the voltage control switch 44 is connected to the secondary side to receive the secondary side voltage generated on the secondary side. VS. The rectifier controller 46 is connected to the voltage controlled switch 44 and the rectifier switch 42. When the secondary side voltage VS rises to a switching voltage value lower than the first voltage value, the rectifier controller 46 controls the rectifier switch 42 to be non-conductive, and after the rectifier switch 42 is non-conductive, the voltage control switch 44 is non-conductive. The voltage dividing capacitor 45 receives the secondary side voltage VS, and the secondary side voltage VS continues to rise to the first voltage value. The capacitance of the voltage dividing capacitor 45 can be adjusted according to requirements, and in principle, can withstand the first voltage value. This first voltage value is the maximum value of the secondary side voltage VS. When the secondary side voltage VS drops to a second voltage value less than the switching voltage value, the voltage control switch 44 assumes an on state, and the rectifier controller 46 detects the second voltage value through the voltage control switch 44 to turn on the rectifier switch. 42. One end of the transient voltage suppressor 48 is connected to the rectifier controller 46 and the voltage controlled switch 44, and the other end is grounded, and the transient voltage suppressor 48 stabilizes the voltage detected by the rectifier controller 46. Therefore, the first voltage value will be greater than the clamp voltage of the transient voltage suppressor 48. The first resistor 50 is connected between the rectifier controller 46 and the rectifier switch 42, the second resistor 52 is connected between the rectifier controller 46 and the voltage control switch 44, and the rectifier controller 46 detects the second voltage through the second resistor 52. value.
壓控開關器44為一N通道金氧半場效電晶體54，其汲極連接整流開關42與二次側，以接收二次側電壓VS，N通道金氧半場效電晶體54之閘極連接一直流電壓源56，以接收直流電壓源56之直流電壓值VCC。直流電壓值VCC小於或等於第一電壓值，直流電壓值VCC大於第二電壓值。直流電壓源56係由電源供應器之輔助電源提供，當此輔助電源並未提供直流電壓值VCC時，同步整流裝置34不運作。此外，使用者可根據需求改變輔助電源之電壓值，如此，二次側電壓VS在不同電壓值，可導通N通道金氧半場效電晶體54。N通道金氧半場效電晶體54之源極與基極互相連接，源極透過第二電阻52連接整流控制器46與暫態電壓抑制器48，且N通道金氧半場效電晶體54之寄生源汲電容58作為分壓電容45。在整流開關42為非導通後，N通道金氧半場效電晶體54為非導通。在二次側電壓VS為第二電壓值時，N通道金氧 半場效電晶體54呈現導通狀態，且整流控制器46偵測第二電壓值。 The voltage control switch 44 is an N-channel MOSFET, and its drain is connected to the rectification switch 42 and the secondary side to receive the secondary side voltage VS, and the gate connection of the N-channel MOS field-effect transistor 54. A DC voltage source 56 receives the DC voltage value VCC of the DC voltage source 56. The DC voltage value VCC is less than or equal to the first voltage value, and the DC voltage value VCC is greater than the second voltage value. The DC voltage source 56 is provided by an auxiliary power source of the power supply. When the auxiliary power source does not provide the DC voltage value VCC, the synchronous rectifying device 34 does not operate. In addition, the user can change the voltage value of the auxiliary power source according to the requirement, so that the secondary side voltage VS can turn on the N-channel MOSFET half-effect transistor 54 at different voltage values. The source of the N-channel MOS field-effect transistor 54 is connected to the base, and the source is connected to the rectifier controller 46 and the transient voltage suppressor 48 through the second resistor 52, and the parasitic N-channel MOS half-effect transistor 54 The source tantalum capacitor 58 serves as a voltage dividing capacitor 45. After the rectifier switch 42 is non-conducting, the N-channel MOS half-effect transistor 54 is non-conductive. N-channel gold oxide when the secondary side voltage VS is the second voltage value The half field effect transistor 54 assumes an on state, and the rectifier controller 46 detects the second voltage value.
以下介紹本發明之同步整流裝置之第一實施例之運作過程。當二次側電壓VS下降至第二電壓值時，寄生源汲電容58與節點D係放電以產生電流通過寄生基汲二極體60。因為直流電壓值VCC大於第二電壓值，所以N通道金氧半場效電晶體54呈導通狀態。當沒有電流通過寄生基汲二極體60時，節點D之電壓等於第二電壓值。換言之，整流控制器46直接接收第二電壓值，以導通整流開關42。當二次側電壓VS上升至切換電壓值時，因為切換電壓值與直流電壓值VCC之壓差，所以N通道金氧半場效電晶體54呈導通狀態。此時，整流控制器46依據切換電壓值控制整流開關42為非導通。當二次側電壓VS繼續上升至第一電壓值時，因為直流電壓值VCC小於或等於第一電壓值，所以N通道金氧半場效電晶體54為非導通，同時二次側電壓VS對寄生源汲電容58充電，並使節點D之電壓等於暫態電壓抑制器48之箝位電壓。因此，整流控制器46能透過寄生源汲電容58接收第一電壓值，以據此關閉整流開關42。由於N通道金氧半場效電晶體54之導通電阻比二極體之導通電阻低，故能降低損失。此外，整流控制器46能透過寄生源汲電容58接收第一電壓值，故能避免整流控制器46被二次側電壓VS損壞，進而大幅提升輸出效率、增加電容可靠度與產品保固年限，並達到精準同步整流。即使省略暫態電壓抑制器48、第一電阻50與第二電阻52之至少其中一者，亦可達到上述目的。 The operation of the first embodiment of the synchronous rectifying device of the present invention will now be described. When the secondary side voltage VS drops to the second voltage value, the parasitic source tantalum capacitor 58 is discharged from the node D to generate a current through the parasitic base diode 60. Since the DC voltage value VCC is greater than the second voltage value, the N-channel MOS field-effect transistor 54 is in an on state. When no current passes through the parasitic bismuth diode 60, the voltage at node D is equal to the second voltage value. In other words, the rectifier controller 46 directly receives the second voltage value to turn on the rectifier switch 42. When the secondary side voltage VS rises to the switching voltage value, the N-channel MOS field-effect transistor 54 is turned on because of the voltage difference between the switching voltage value and the DC voltage value VCC. At this time, the rectifier controller 46 controls the rectifier switch 42 to be non-conductive according to the switching voltage value. When the secondary side voltage VS continues to rise to the first voltage value, since the DC voltage value VCC is less than or equal to the first voltage value, the N-channel MOS field-effect transistor 54 is non-conducting, and the secondary side voltage VS is parasitic. The source tantalum capacitor 58 is charged and the voltage at node D is equal to the clamp voltage of the transient voltage suppressor 48. Therefore, the rectifier controller 46 can receive the first voltage value through the parasitic source tantalum capacitor 58 to turn off the rectifier switch 42 accordingly. Since the on-resistance of the N-channel MOS field-effect transistor 54 is lower than the on-resistance of the diode, the loss can be reduced. In addition, the rectification controller 46 can receive the first voltage value through the parasitic source tantalum capacitor 58, so that the rectification controller 46 can be prevented from being damaged by the secondary side voltage VS, thereby greatly improving the output efficiency, increasing the capacitance reliability and the product warranty period, and Achieve precise synchronous rectification. Even if the transient voltage suppressor 48, at least one of the first resistor 50 and the second resistor 52 is omitted, the above object can be attained.
以下介紹本發明之同步整流裝置之第二實施例，如第5圖所示。第二實施例與第一實施例差別在於壓控開關器44。壓控開關器44更包含一輔助電容62、一N通道金氧半場效電晶體54與一二極體64。N通道金氧半場效電晶體54之汲極連接整流開關42與二次側，以接收二次側電壓VS，N通道金氧半場效電晶體54之閘極連接一直流電壓源56，以接收直流電壓源56之直 流電壓值VCC。直流電壓值VCC小於或等於第一電壓值，直流電壓值VCC大於第二電壓值。直流電壓源56係由電源供應器之輔助電源提供，當此輔助電源並未提供直流電壓值VCC時，同步整流裝置不運作。此外，使用者可根據需求改變輔助電源之電壓值，如此，二次側電壓VS在不同電壓值，可導通N通道金氧半場效電晶體54。N通道金氧半場效電晶體54之源極與基極互相連接，源極透過第二電阻52連接整流控制器46與暫態電壓抑制器48，且輔助電容62連接於汲極與源極之間，N通道金氧半場效電晶體54之寄生源汲電容58與輔助電容62形成分壓電容45。在整流開關42為非導通後，N通道金氧半場效電晶體54為非導通。二極體64之陽極連接源極，二極體64之陰極連接汲極。在二次側電壓VS為第二電壓值時，N通道金氧半場效電晶體54呈現導通狀態，且整流控制器46偵測第二電壓值。 Next, a second embodiment of the synchronous rectifying device of the present invention will be described, as shown in Fig. 5. The second embodiment differs from the first embodiment in the voltage controlled switch 44. The voltage controlled switch 44 further includes an auxiliary capacitor 62, an N-channel MOS field-effect transistor 54 and a diode 64. The drain of the N-channel MOS half-effect transistor 54 is connected to the rectifying switch 42 and the secondary side to receive the secondary side voltage VS, and the gate of the N-channel MOS field-effect transistor 54 is connected to the DC voltage source 56 for receiving DC voltage source 56 straight The current voltage value is VCC. The DC voltage value VCC is less than or equal to the first voltage value, and the DC voltage value VCC is greater than the second voltage value. The DC voltage source 56 is provided by an auxiliary power source of the power supply. When the auxiliary power source does not provide the DC voltage value VCC, the synchronous rectification device does not operate. In addition, the user can change the voltage value of the auxiliary power source according to the requirement, so that the secondary side voltage VS can turn on the N-channel MOSFET half-effect transistor 54 at different voltage values. The source of the N-channel MOS field-effect transistor 54 is connected to the base, the source is connected to the rectifier controller 46 and the transient voltage suppressor 48 through the second resistor 52, and the auxiliary capacitor 62 is connected to the drain and the source. The parasitic source tantalum capacitor 58 of the N-channel MOS field-effect transistor 54 and the auxiliary capacitor 62 form a voltage dividing capacitor 45. After the rectifier switch 42 is non-conducting, the N-channel MOS half-effect transistor 54 is non-conductive. The anode of the diode 64 is connected to the source, and the cathode of the diode 64 is connected to the drain. When the secondary side voltage VS is the second voltage value, the N-channel MOS half-effect transistor 54 assumes an on state, and the rectifier controller 46 detects the second voltage value.
以下介紹本發明之同步整流裝置之第二實施例之運作過程。當二次側電壓VS下降至第二電壓值時，輔助電容62、寄生源汲電容58與節點D係放電以產生電流通過寄生基汲二極體60與二極體64。因為直流電壓值VCC大於第二電壓值，所以N通道金氧半場效電晶體54呈導通狀態。當沒有電流通過寄生基汲二極體60與二極體64時，節點D之電壓等於第二電壓值。換言之，整流控制器46直接接收第二電壓值，以導通整流開關42。當二次側電壓VS上升至切換電壓值時，因為切換電壓值與直流電壓值VCC之壓差，所以N通道金氧半場效電晶體54呈導通狀態。此時，整流控制器46依據切換電壓值控制整流開關42為非導通。當二次側電壓VS繼續上升至第一電壓值時，因為直流電壓值VCC小於或等於第一電壓值，所以N通道金氧半場效電晶體54為非導通，同時二次側電壓VS對寄生源汲電容58與輔助電容62充電，並使節點D之電壓等於暫態電壓抑制器48之箝位電壓。因此，整流控制器46能透過寄生源汲電容58與輔助電容62接收第一電壓值， 以據此關閉整流開關42。由於N通道金氧半場效電晶體54之導通電阻比二極體之導通電阻低，故能降低損失。此外，整流控制器46能透過寄生源汲電容58與輔助電容62接收第一電壓值，故能避免整流控制器46被二次側電壓VS損壞，進而大幅提升輸出效率、增加電容可靠度與產品保固年限，並達到精準同步整流。 The operation of the second embodiment of the synchronous rectifying device of the present invention will now be described. When the secondary side voltage VS drops to the second voltage value, the auxiliary capacitor 62, the parasitic source tantalum capacitor 58 and the node D are discharged to generate a current through the parasitic base diode 60 and the diode 64. Since the DC voltage value VCC is greater than the second voltage value, the N-channel MOS field-effect transistor 54 is in an on state. When no current flows through the parasitic bismuth diode 60 and the diode 64, the voltage at the node D is equal to the second voltage value. In other words, the rectifier controller 46 directly receives the second voltage value to turn on the rectifier switch 42. When the secondary side voltage VS rises to the switching voltage value, the N-channel MOS field-effect transistor 54 is turned on because of the voltage difference between the switching voltage value and the DC voltage value VCC. At this time, the rectifier controller 46 controls the rectifier switch 42 to be non-conductive according to the switching voltage value. When the secondary side voltage VS continues to rise to the first voltage value, since the DC voltage value VCC is less than or equal to the first voltage value, the N-channel MOS field-effect transistor 54 is non-conducting, and the secondary side voltage VS is parasitic. The source tantalum capacitor 58 is charged to the auxiliary capacitor 62 and the voltage at node D is equal to the clamp voltage of the transient voltage suppressor 48. Therefore, the rectifier controller 46 can receive the first voltage value through the parasitic source tantalum capacitor 58 and the auxiliary capacitor 62. Thereby, the rectifier switch 42 is turned off. Since the on-resistance of the N-channel MOS field-effect transistor 54 is lower than the on-resistance of the diode, the loss can be reduced. In addition, the rectifier controller 46 can receive the first voltage value through the parasitic source tantalum capacitor 58 and the auxiliary capacitor 62, so that the rectifier controller 46 can be prevented from being damaged by the secondary side voltage VS, thereby greatly improving the output efficiency, increasing the capacitance reliability, and the product. Guaranteed years and achieve precise synchronous rectification.
以下介紹本發明之同步整流裝置之第三實施例，如第6圖所示。第三實施例與第二實施例差別在於壓控開關器44。壓控開關器44更包含一NPN雙載子接面電晶體66與一二極體64。NPN雙載子接面電晶體66之射極連接整流開關42與二次側，以接收二次側電壓VS，NPN雙載子接面電晶體66之基極連接一直流電壓源56，以接收直流電壓源56之直流電壓值VCC。直流電壓值VCC小於或等於第一電壓值，直流電壓值VCC大於第二電壓值。直流電壓源56係由電源供應器之輔助電源提供，當此輔助電源並未提供直流電壓值VCC時，同步整流裝置不運作。此外，使用者可根據需求改變輔助電源之電壓值，如此，二次側電壓VS在不同電壓值，可導通NPN雙載子接面電晶體66。分壓電容45連接於NPN雙載子接面電晶體66之射極與集極間，集極透過第二電阻52連接整流控制器46與暫態電壓抑制器48。在整流開關42為非導通後，NPN雙載子接面電晶體66為非導通。二極體64之陽極連接集極二極體64之陰極連接射極。在二次側電壓VS為第二電壓值時，NPN雙載子接面電晶體66呈現導通狀態，且整流控制器46偵測第二電壓值。 Next, a third embodiment of the synchronous rectifying device of the present invention will be described, as shown in Fig. 6. The third embodiment differs from the second embodiment in the voltage controlled switch 44. The voltage controlled switch 44 further includes an NPN bipolar junction transistor 66 and a diode 64. The emitter of the NPN bipolar junction transistor 66 is connected to the rectifier switch 42 and the secondary side to receive the secondary side voltage VS. The base of the NPN bipolar junction transistor 66 is connected to the DC voltage source 56 for reception. The DC voltage source V of the DC voltage source 56 is VCC. The DC voltage value VCC is less than or equal to the first voltage value, and the DC voltage value VCC is greater than the second voltage value. The DC voltage source 56 is provided by an auxiliary power source of the power supply. When the auxiliary power source does not provide the DC voltage value VCC, the synchronous rectification device does not operate. In addition, the user can change the voltage value of the auxiliary power source according to the requirement. Thus, the secondary side voltage VS can turn on the NPN bipolar junction transistor 66 at different voltage values. The voltage dividing capacitor 45 is connected between the emitter and the collector of the NPN bipolar junction transistor 66, and the collector is connected to the rectifier controller 46 and the transient voltage suppressor 48 through the second resistor 52. After the rectifier switch 42 is non-conducting, the NPN bipolar junction transistor 66 is non-conducting. The anode of the diode 64 is connected to the cathode of the collector diode 64 to connect the emitter. When the secondary side voltage VS is the second voltage value, the NPN bipolar junction transistor 66 assumes an on state, and the rectifier controller 46 detects the second voltage value.
以下介紹本發明之同步整流裝置之第三實施例之運作過程。當二次側電壓VS下降至第二電壓值時，分壓電容45與節點D係放電以產生電流通過二極體64。因為直流電壓值VCC大於第二電壓值，所以NPN雙載子接面電晶體66呈導通狀態。當沒有電流通過二極體64時，節點D之電壓等於第二電壓值。換言之，整流控制器46直接接收第二電壓值，以導通 整流開關42。當二次側電壓VS上升至切換電壓值時，因為切換電壓值與直流電壓值VCC之壓差，所以NPN雙載子接面電晶體66呈導通狀態。此時，整流控制器46依據切換電壓值控制整流開關42為非導通。當二次側電壓VS繼續上升至第一電壓值時，因為直流電壓值VCC小於或等於第一電壓值，所以NPN雙載子接面電晶體66為非導通，同時二次側電壓VS對分壓電容45充電，並使節點D之電壓等於暫態電壓抑制器48之箝位電壓。因此，整流控制器46能透過分壓電容45接收第一電壓值，以據此關閉整流開關42。由於NPN雙載子接面電晶體66之導通電阻比二極體之導通電阻低，故能降低損失。此外，整流控制器46能透過分壓電容45接收第一電壓值，故能避免整流控制器46被二次側電壓VS損壞，進而大幅提升輸出效率、增加電容可靠度與產品保固年限，並達到精準同步整流。 The operation of the third embodiment of the synchronous rectifying device of the present invention will now be described. When the secondary side voltage VS drops to the second voltage value, the voltage dividing capacitor 45 and the node D are discharged to generate a current through the diode 64. Since the DC voltage value VCC is greater than the second voltage value, the NPN bipolar junction transistor 66 is in an on state. When no current flows through the diode 64, the voltage at node D is equal to the second voltage value. In other words, the rectifier controller 46 directly receives the second voltage value to conduct Rectifier switch 42. When the secondary side voltage VS rises to the switching voltage value, the NPN bipolar junction transistor 66 is in an on state due to the voltage difference between the switching voltage value and the DC voltage value VCC. At this time, the rectifier controller 46 controls the rectifier switch 42 to be non-conductive according to the switching voltage value. When the secondary side voltage VS continues to rise to the first voltage value, since the DC voltage value VCC is less than or equal to the first voltage value, the NPN bipolar junction transistor 66 is non-conducting, and the secondary side voltage VS is divided. The voltage capacitor 45 is charged and the voltage at node D is equal to the clamp voltage of the transient voltage suppressor 48. Therefore, the rectifier controller 46 can receive the first voltage value through the voltage dividing capacitor 45 to thereby turn off the rectifier switch 42. Since the on-resistance of the NPN bipolar junction transistor 66 is lower than the on-resistance of the diode, the loss can be reduced. In addition, the rectifier controller 46 can receive the first voltage value through the voltage dividing capacitor 45, so that the rectifier controller 46 can be prevented from being damaged by the secondary side voltage VS, thereby greatly improving the output efficiency, increasing the capacitance reliability and the product warranty period, and achieving Precision synchronous rectification.
此外，壓控開關器44亦可由P通道金氧半場效電晶體與PNP雙載子接面電晶體所組成，壓控開關器44之操作與上述實施例類似，於此不再贅述。 In addition, the voltage-controlled switch 44 can also be composed of a P-channel MOSFET and a PNP dual-carrier junction transistor. The operation of the voltage-controlled switch 44 is similar to that of the above embodiment, and will not be described herein.
綜上所述，本發明利用具有分壓電容之壓控開關器偵測二次側電壓，以據此切換同步開關，進而大幅提升輸出效率、降低損失、增加電容可靠度與產品保固年限，並達到精準同步整流。 In summary, the present invention utilizes a voltage-controlled switch with a voltage-dividing capacitor to detect the secondary side voltage, thereby switching the synchronous switch accordingly, thereby greatly improving output efficiency, reducing loss, increasing capacitance reliability, and product warranty period, and Achieve precise synchronous rectification.
以上所述者，僅為本發明一較佳實施例而已，並非用來限定本發明實施之範圍，故舉凡依本發明申請專利範圍所述之形狀、構造、特徵及精神所為之均等變化與修飾，均應包括於本發明之申請專利範圍內。 The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, so that the shapes, structures, features, and spirits described in the claims of the present invention are equally varied and modified. All should be included in the scope of the patent application of the present invention.
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| US6188592B1 (en) * | 1999-11-05 | 2001-02-13 | Ericsson Inc. | Externally-driven scheme for synchronous rectification |
| TWM294158U (en) * | 2006-01-12 | 2006-07-11 | System General Corp | Control circuit associated with saturable inductor operated as synchronous rectifier for forward power converter |
| CN106169870A (en) * | 2015-05-21 | 2016-11-30 | 立锜科技股份有限公司 | There is power supply changeover device and the control method thereof of synchronization control function |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US6188592B1 (en) * | 1999-11-05 | 2001-02-13 | Ericsson Inc. | Externally-driven scheme for synchronous rectification |
| TWM294158U (en) * | 2006-01-12 | 2006-07-11 | System General Corp | Control circuit associated with saturable inductor operated as synchronous rectifier for forward power converter |
| CN106169870A (en) * | 2015-05-21 | 2016-11-30 | 立锜科技股份有限公司 | There is power supply changeover device and the control method thereof of synchronization control function |
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