200810339 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種直流電源轉換電路，尤指一種具定電流輸 出之直流電源轉換電路。 【先前技術】 近年來’發光二極體（Light Emitting Diode，LED )已普遍應 用使用於資訊、通訊及消費性電子產品的指示燈與顯示裝置上， 如父通唬誌燈等等。不同於一般白熾燈泡，發光二極體係屬冷發 光凡件，因此具有耗電量低、元件壽命長、無須暖燈時間以及反 應速度快等優點，再加上其體積小、耐震動、適合量產，因此容 易配合應用需求而製成極小或陣列式的元件。在發光二極體的物 理特ϋ中，發光二極體之發光程度係與其通過的電流成正比，而 通過發光二極體之電流隨著發光二極體之—順向偏壓呈指數型的 立曰加也就疋說，當通過的電流越大，二極體發光的強度也越高。 另外’备週遭每境的溫度改變時，二極體的電流亦呈現指數型的 改變。在許多應财，如液晶顯示ϋ的背光、交通麟等等，皆 需要發光二極體持續以相同程度發光，以免造成視覺上閃爍不定 的見象I生。因此’―般來說，發光二極體需要一電壓轉換電路 來控制其電流，以穩定發光亮度。 —二翏考第丨圖’第丨圖為一習知直流對直流電壓轉換器1〇 之不意圖。直流對直流電壓轉換器10包含有-直流電源100、一 200810339 開關電晶體102、一電阻i〇4、一二極體ι〇6、一電感1〇8、一電 容no、一負載112、一控制訊號產生器114及一電壓轉換器（1^幼 sider) 116。控制訊號產生器114可根據電阻1〇4的輸出電流，產 生一控制訊號Sc，並透過電壓轉換器116改變控制訊號&之電壓 準位，以控制開關電晶體1〇2的開啟或關閉，其工作原理如下。 當開關電晶體102導通時，二極體106承受反偏壓而阻斷一迴路 L1，使得電源1〇〇對電感108儲能，此時電阻1〇4之電流逐漸上 升。g電阻104之電流上升至一預設準位，控制訊號產生器 透過控制訊號Sc關閉開關電晶體102。一旦開關電晶體1〇2關閉， 則電感108會產生極性相反的電壓，二極體1〇6承受順向偏壓而 導通迴路L1，此時電阻1〇4之電流開始下降。換句話說，習知直 流對直流電壓轉換器10透過開關電晶體1〇2的導通與關閉，使負 載112之電流維持在一微小擺幅内，穩定負載112之電流。 在習知直流對直流電壓轉換器10中，由於控制訊號產生器 114與電路中的各元件共接同一接地端(3^1>使得開關電晶體1〇2 與控制訊號產生器114分處不同電壓準位，開關電晶體1〇2位於 電>1南侧（high side)，而控制訊號產生器114位於一電壓低側。 因此，為了使控制訊號產生器114產生之控制訊號&能適當地控 制開關電晶體102，習知直流對直流電壓轉換器1〇需要利用電壓 轉換器116預先改變控制訊號Sc的電壓準位，即將控制訊號& 的電壓準位提昇至電壓高側，所以電壓轉換器116通常為變壓器 組合。因此，對於習知直流對直流電壓轉換器1〇來說，電路的複 ^0810339 雜度仍較高且佔用面積較大。 【發明内容】 因此，本發明係提供一 ”疋“輪出之直流電源轉換電路 本發明係揭露-種具定電流輸出之 流電源轉換電路包含有一直μ電源轉換電路。該j 產哇哭,L電反源、—驅動電路及一柃制叩狀 有一開關、-電阻、—二跡/、H源。該驅動電路包含 接於該直流電壓源，一；感。該開私 端。該開_來根據該第^收—控制訊號，以及—第三 第一端至該㈣關閉該 -=:Γ_"-接：：= ^-接⑽。該電感具有—第—端綠於 知，及一第二端耦接於一 接地 之第二端、第三端，及謂二制訊號產生器_於該開關 生该控制訊號至該開闕之該第二端。 u f實施方式】 請參考第2圖，證？4 流電源轉換電路2〇之矛音圖為本/1日月一實施例具定電流輸出之直 流電壓源·、,電;^細糊嫩2G包含有一直 勒軍路22、一控制訊號產生器214及一負載 200810339 212。直流電壓源200係、用來提供—直流電源給直流電源轉換電路 20。驅動電路22之構成元件触於第丨圖之直流對直流電壓轉換 器10，其包含有一開關202、一電阻2〇4、一二極體2〇6、一電感 208及一濾波電容210。開關202具有一第一端2022耦接於直流 電壓源200，-第二端2024用來接收控制訊號產生器214所產生 之-控制訊號Sc，以及-第三端2〇26。開關2〇2是用來根據第二 端2〇24所接收之控制訊號Sc，導通或關閉第一端MU至第三端 2026之連結。因此，開關202可為一金屬氧化半導體場效電晶體 (metal-oxide-semiconductor field-effect transistor，MOSFET),則 第-端2022係汲極，第二端2024係閘極，第三端2026係源極。 或者，開關202亦可為一雙極性接面電晶體（Bip〇lar Juncti〇n Transistor ’ BJT) ’則第一端2022係集極，第二端2〇24係基極， 第二端2026係射極。不同於第1圖之電阻1〇4偶接於電容及 負載112之間，電阻204偶接於開關202與電感208之間，其中 電阻204與電感208之間設有一第一接地端GND1。二極體200 耦接於開關202之第三端2026與一第二接地端GND2之間。二極 體206通常為-pn接面半導體元件，圖示中的上端為n極而下端 為Ρ極。另外，第一接地端GND1係用來提供控制訊號產生器214 之電源接地，而第二接地端GND2係用來提供直流電壓源2〇〇之 電源接地，也就是說，控制訊號產生器26與第2圖中其他元件不 共地。電感208偶接於第一接地端GND1及負載212之間，用來 儲存或釋放直流電壓源2⑻提供之能量，可控制電流的最大或最 小值。濾波電容210耦接於電感208與第二接地端GND2之間， 200810339 用來;慮除輸出至負載212之電流的雜訊。控制訊號產生器214通 常為脈寬調變ϋ (PulsewidthmGdulat()〇,緘於電阻綱之兩端 (其中-端即為第-接地端GND1)。控制訊號產生器214透過第 接地hGNDl可感測電阻2〇4之電流，並根據電流變化產生適 合的控制訊號Sc至開關202之第二端2024。 負載212是需要工作在穩定電流下的元件，以發光二極體 (Light emitting diode，LED)為例，其發光強度與通過的電流成 比例，因此發光二極體需要穩定的電流來維持固定的亮度，以免 ie成閃;^不疋的情況發生。為了提供穩定的電流給負載，控制 訊號產生器214可感測電阻204之電流，產生控制訊號^，以控 制開關202的開啟或關閉，從而將輸出至負載212之電流維持在 一疋的範圍内，其工作原理如下。當開關2〇2導通時，二極體 承文反偏壓而阻斷一迴路L2，使得直流電壓源2〇〇對電感2〇8儲 能’此時電阻204的電流隨著電感2〇8的電流逐步往上升而上升。 當電阻204的電流上升至一預定最大值時，控制訊號產生器214 透過控制訊號Sc關閉開關202。一旦開關202關閉，直流電壓源 200無法知供此畺，電感208會產生極性相反的電壓，則二極體 206運作於順向偏壓下導通迴路L2，此時，電阻2〇4的電流隨著 電感208的電流下降而下降。當電阻204的電流下降至一預定最 小值時，控制訊號產生器214再透過控制訊號&開啟開關2〇2， 如此一來使負載212的電流得以維持在一定的範圍内。因此，在 直流電源轉換電路20中，控制訊號產生器214不與其他元件共於 200810339 第二接地端GND2，而改接於第一接地端，並且電阻2〇4 文接於開關2G2與電感208之間，使控制訊號產生器214產生之 &制射uSe之電壓準位以處於電壓高側，可直接將控制訊號& 送至開關202。 請參考第3圖’第3圖為本發明一實施例具定電流輸出之直 机電源轉換電路3〇之示意圖。直流電源轉換電路如包含有一直 机電壓源300、-驅動電路32、一控制訊號產生器314及一負載 312。直流電壓源3〇〇係用紐供一直流電源給直流電源轉換電路 3〇 °驅動電路32包含有一開關302、一第一電阻3〇4、一第二電 阻314、一二極體306、一電感及-濾、波電容310。第一電阻 304及帛一電且314之一端皆轉接於第一接地端G顧，另一端 耗接於控舰财生器314。由第3圖可知，她於第2圖之驅動 電路22，驅動電路32係增加第二電阻314輕接於一第一接地端 GND1。及二極體308之間。因此，於開關3〇2導通時，控制訊號 產生器314可根據第一電阻3〇4上電流的變化，產生一控制訊號 Sc ’而於開關3〇2關閉時’控制訊號產生器314則根據第二電阻 314上電流的變化，產生控制訊號Sc。 因此，當開關302導通時，二極體306較反偏壓而阻斷一 迴路L3，使得第二電阻314上無電流通過，此時直流電壓源_ 對電感308儲能，則第一電阻3〇4的電流隨著電感3〇8的電流逐 步往上升而上升。當電阻3〇4的電流上升至一預定最大值時，控 200810339 制訊號產生器314透過控制訊號Sc關閉開關302。一旦開關302 關閉，直流電壓源300無法提供能量，第一電阻304因此無電流 通過’此時電感308會產生極性相反的電壓，使二極體306運作 於順向偏壓下導通迴路L3，則第二電阻314上有電流通過且其電 流大小隨著電感308的電流下降而下降。當第二電阻314的電流 下降至一預定最小值時，控制訊號產生器314再透過控制訊號& 開啟開關202,如此一來使負載312的電流得以維持在一定的範圍 内。因此，在直流電源轉換電路3〇中，控制訊號產生器214不與 其他元件共於第二接地端GND2，而改接於第一接地端GND卜並 且於開關302導通及關閉期間，分別根據第一電阻及第二電 阻314上的電流變化，產生控制訊號&。控制訊號產生器314產 生之控制訊號Sc之電壓準位係處於電壓高側，可直接將控制訊號 Sc送至開關302，不需通過其它變壓元件。 綜上所述，在習知技術中，電阻係接於負載之後端，且控制 而虎產生H與源共地，使產生之控制訊賴關處於不同 電壓準位，因此習知直流電轉換電路需要電壓轉換器來調整控 制訊號之電壓準位。不同於習知技術，在本發明直流電源轉^ 路中，控制訊號產生器不與其他元件共接於同一接地端，並將電 阻設置於«之後，使㈣訊號產生贿_同處於電壓高側， 使控制訊號可直接傳送至開關，不需要使用電壓轉換器。因此， 本發明直流輯轉換電路將電阻設置於高壓側並使控制訊號產生 器不與其他元件共地，可減低電路複雜度並節省成本。 11 200810339 以上所述僅林㈣之健實施例，凡依本發财請專利範 圍所做之均等變化與修飾，皆應屬本發明之涵蓋範圍。 【圖式簡單說明】 第1圖為一習知降壓式直流對直流電壓轉換器之示辛图 第2圖為本發明-實施例具定電流輸出之直流物轉二電路之示 意圖。 第3圖為本發明-實施例具定電流輸出之直流電源轉換電路之示 意圖。 Μ 【主要元件符號說明】 10 直k對直流電壓轉換器 102 開關電晶體 20、30 直流電源轉換電路 22 > 32 驅動電路 100、200、300 直流電壓源 202 、 302 開關 104、204、304、314 電阻 106、206、306 二極體 108、208、308 電感 110、210、310 電容 112、212、312 負載 114、214 、314 控制訊號產生器 12 200810339 116 電壓轉換器 Sc 控制訊號 U、L2、L3 迴路 GND、GND 卜 GND2 接地端 2022、2024、2026、3022、3024、3026 端點 13200810339 IX. Description of the Invention: [Technical Field] The present invention relates to a DC power conversion circuit, and more particularly to a DC power conversion circuit having a constant current output. [Prior Art] In recent years, Light Emitting Diode (LED) has been widely used in indicator lights and display devices for information, communication and consumer electronics, such as the father-to-be. Different from ordinary incandescent light bulbs, the light-emitting diode system is a cold-lighting part, so it has the advantages of low power consumption, long component life, no need for warming time and fast reaction speed, plus its small size, vibration resistance and suitable amount. Production, so it is easy to make small or array components with the application requirements. In the physical characteristics of the light-emitting diode, the degree of light emission of the light-emitting diode is proportional to the current passing through it, and the current through the light-emitting diode is exponentially biased with the forward bias of the light-emitting diode. Li Jin also said that the greater the current passing, the higher the intensity of the LED illumination. In addition, the current of the diode changes exponentially when the temperature of each environment changes. In many financial applications, such as backlighting of liquid crystal display, traffic lining, etc., it is required that the light-emitting diodes continue to emit light at the same level, so as to avoid visually flickering the appearance of I. Therefore, in general, a light-emitting diode requires a voltage conversion circuit to control its current to stabilize the luminance. The second figure is a conventional DC-to-DC voltage converter. The DC-to-DC voltage converter 10 includes a DC power supply 100, a 200810339 switching transistor 102, a resistor i〇4, a diode ι6, an inductor 1〇8, a capacitor no, a load 112, and a The control signal generator 114 and a voltage converter (1) are 116. The control signal generator 114 can generate a control signal Sc according to the output current of the resistor 1〇4, and change the voltage level of the control signal & through the voltage converter 116 to control the opening or closing of the switching transistor 1〇2. Its working principle is as follows. When the switching transistor 102 is turned on, the diode 106 is subjected to a reverse bias to block the first circuit L1, so that the power source 1 储 stores energy to the inductor 108, and the current of the resistor 1 〇 4 gradually rises. The current of the g resistor 104 rises to a predetermined level, and the control signal generator turns off the switch transistor 102 through the control signal Sc. Once the switching transistor 1〇2 is turned off, the inductor 108 generates a voltage of opposite polarity, and the diode 1〇6 is subjected to a forward bias to turn on the loop L1, at which time the current of the resistor 1〇4 begins to drop. In other words, the conventional DC current is turned on and off by the DC voltage converter 10 through the switching transistor 1〇2, so that the current of the load 112 is maintained in a small swing, and the current of the load 112 is stabilized. In the conventional DC-to-DC voltage converter 10, since the control signal generator 114 and the components in the circuit are connected to the same ground terminal (3^1>, the switching transistor 1〇2 is different from the control signal generator 114. At the voltage level, the switching transistor 1〇2 is located on the high side of the electric >1, and the control signal generator 114 is located on the low side of the voltage. Therefore, in order to enable the control signal generator 114 to generate the control signal & Appropriately controlling the switching transistor 102, it is necessary for the DC-to-DC voltage converter 1 to use the voltage converter 116 to change the voltage level of the control signal Sc in advance, that is, to raise the voltage level of the control signal & to the high side of the voltage, so The voltage converter 116 is usually a transformer combination. Therefore, for the conventional DC-to-DC voltage converter 1〇, the circuit has a high complexity and a large occupied area. [Invention] Therefore, the present invention is Providing a "疋" round-off DC power conversion circuit. The present invention discloses that a constant current output current power conversion circuit includes a constant power conversion circuit. The j produces wow, L power The anti-source, the driving circuit and the one-chip device have a switch, a resistor, a two-track/, and a H source. The driving circuit includes a DC voltage source, a sense; the open end. According to the first receiving-control signal, and the third first end to the (four) closing the -=:Γ_"-connecting::=^-connecting (10). The inductor has a -th-end green, and a first The second end is coupled to a second end of the ground, the third end, and the second signal generator _ the switch generates the control signal to the second end of the opening. uf implementation manner] Please refer to FIG. , certificate? 4 flow power conversion circuit 2 矛 矛 音 图 为本 为本 / / / / / 实施 实施 实施 实施 实施 实施 实施 实施 实施 实施 实施 实施 实施 实施 实施 实施 实施 实施 直流 直流 直流 直流 直流 直流 直流 直流 直流 直流 直流 直流 直流 直流 直流 直流The control signal generator 214 and a load 200810339 212. The DC voltage source 200 is used to provide a DC power supply to the DC power conversion circuit 20. The components of the drive circuit 22 are touched by the DC-to-DC voltage converter 10 of FIG. The utility model comprises a switch 202, a resistor 2〇4, a diode 2〇6, an inductor 208 and a filter capacitor 210. The switch 202 has a first end 2022 coupled to the DC voltage source 200, a second end 2024 for receiving the control signal Sc generated by the control signal generator 214, and a third terminal 2〇26. The switch 2〇2 It is used to turn on or off the connection of the first end MU to the third end 2026 according to the control signal Sc received by the second end 2〇24. Therefore, the switch 202 can be a metal oxide semiconductor field effect transistor (metal-oxide) -Semiconductor field-effect transistor (MOSFET), the first end 2022 is a drain, the second end 2024 is a gate, and the third end 2026 is a source. Alternatively, the switch 202 can also be a bipolar junction transistor (Bip〇lar Juncti〇n Transistor 'BJT)', the first end 2022 is a collector, the second end is 2〇24 base, and the second end 2026 is Shooting pole. The resistor 1〇4 is different between the capacitor and the load 112, and the resistor 204 is coupled between the switch 202 and the inductor 208. A first ground terminal GND1 is disposed between the resistor 204 and the inductor 208. The diode 200 is coupled between the third end 2026 of the switch 202 and a second ground GND2. The diode 206 is typically a -pn junction semiconductor device, the upper end of which is n pole and the lower end is drained. In addition, the first ground GND1 is used to provide the power supply ground of the control signal generator 214, and the second ground GND2 is used to provide the power supply grounding of the DC voltage source 2, that is, the control signal generator 26 is The other elements in Figure 2 are not common. The inductor 208 is coupled between the first ground GND1 and the load 212 for storing or releasing the energy provided by the DC voltage source 2 (8) to control the maximum or minimum value of the current. The filter capacitor 210 is coupled between the inductor 208 and the second ground GND2, and is used in 200810339 to consider the noise of the current output to the load 212. The control signal generator 214 is usually pulse width modulation ϋ (PulsewidthmGdulat() 缄, at both ends of the resistor (where the - terminal is the ground-to-ground GND1). The control signal generator 214 can be sensed through the ground hGND1 The current of the resistor 2〇4, and according to the current change, generates a suitable control signal Sc to the second end 2024 of the switch 202. The load 212 is a component that needs to operate under a stable current to emit a light emitting diode (LED). For example, the luminous intensity is proportional to the current passing through, so the light-emitting diode needs a stable current to maintain a fixed brightness, so as to avoid the occurrence of flashing. In order to provide a stable current to the load, the control signal The generator 214 can sense the current of the resistor 204 to generate a control signal ^ to control the opening or closing of the switch 202 to maintain the current output to the load 212 within a range of 疋. The operation principle is as follows: when the switch 2 〇 2 When conducting, the diode body is reverse biased to block the primary circuit L2, so that the DC voltage source 2〇〇 stores energy to the inductor 2〇8'. At this time, the current of the resistor 204 gradually rises with the current of the inductor 2〇8. When the current of the resistor 204 rises to a predetermined maximum value, the control signal generator 214 turns off the switch 202 through the control signal Sc. Once the switch 202 is turned off, the DC voltage source 200 is unknown, and the inductor 208 has the opposite polarity. The voltage of the diode 206 operates in the forward biased loop L2. At this time, the current of the resistor 2〇4 decreases as the current of the inductor 208 decreases. When the current of the resistor 204 drops to a predetermined minimum value. The control signal generator 214 then turns on the switch 2〇2 through the control signal &ling, so that the current of the load 212 is maintained within a certain range. Therefore, in the DC power conversion circuit 20, the control signal generator 214 does not Cooperating with other components in 200810339, the second grounding terminal GND2, and being connected to the first grounding terminal, and the resistor 2〇4 is connected between the switch 2G2 and the inductor 208, so that the control signal generator 214 generates & The voltage level is on the high side of the voltage, and the control signal & can be directly sent to the switch 202. Please refer to FIG. 3, FIG. 3 is a diagram of a direct power supply with a constant current output according to an embodiment of the present invention. The schematic diagram of the circuit 3. The DC power conversion circuit includes an all-wheel voltage source 300, a drive circuit 32, a control signal generator 314, and a load 312. The DC voltage source 3 is used for the DC power supply to the DC. The power conversion circuit 3 驱动 drive circuit 32 includes a switch 302, a first resistor 3〇4, a second resistor 314, a diode 306, an inductor and a filter, a wave capacitor 310. The first resistor 304 and the 帛One of the terminals 314 is switched to the first ground terminal G and the other end is connected to the control ship hopper 314. As can be seen from Fig. 3, in the driving circuit 22 of Fig. 2, the driving circuit 32 is connected to the first grounding terminal GND1 by adding the second resistor 314. And between the diodes 308. Therefore, when the switch 3〇2 is turned on, the control signal generator 314 can generate a control signal Sc′ according to the change of the current on the first resistor 3〇4, and when the switch 3〇2 is turned off, the control signal generator 314 is based on A change in current on the second resistor 314 produces a control signal Sc. Therefore, when the switch 302 is turned on, the diode 306 is reverse biased to block the first loop L3, so that no current flows through the second resistor 314. At this time, the DC voltage source _ stores energy to the inductor 308, and the first resistor 3 The current of 〇4 rises as the current of the inductor 3〇8 gradually rises. When the current of the resistor 3〇4 rises to a predetermined maximum value, the control signal generator 314 of the 200810339 turns off the switch 302 through the control signal Sc. Once the switch 302 is turned off, the DC voltage source 300 is unable to supply energy, and the first resistor 304 therefore has no current flow. At this time, the inductor 308 generates a voltage of opposite polarity, so that the diode 306 operates under the forward biased conduction loop L3. A current flows through the second resistor 314 and its current level decreases as the current of the inductor 308 decreases. When the current of the second resistor 314 drops to a predetermined minimum value, the control signal generator 314 turns on the control signal & turn on the switch 202, so that the current of the load 312 is maintained within a certain range. Therefore, in the DC power conversion circuit 3, the control signal generator 214 is not shared with the other components on the second ground GND2, but is connected to the first ground GND and is turned on and off during the switch 302, respectively. A change in current across a resistor and second resistor 314 produces a control signal & The voltage level of the control signal Sc generated by the control signal generator 314 is on the high voltage side, and the control signal Sc can be directly sent to the switch 302 without passing through other transformer components. In summary, in the prior art, the resistor is connected to the rear end of the load, and the control generates the H and the source together, so that the generated control signal is at different voltage levels, so the conventional DC conversion circuit needs The voltage converter adjusts the voltage level of the control signal. Different from the conventional technology, in the DC power supply circuit of the present invention, the control signal generator is not connected to the same grounding terminal with other components, and the resistance is set to «after the (4) signal is generated and the voltage is high. , so that the control signal can be directly transmitted to the switch without using a voltage converter. Therefore, the DC conversion circuit of the present invention sets the resistance to the high voltage side and makes the control signal generator not shared with other components, thereby reducing circuit complexity and saving cost. 11 200810339 The above-mentioned examples of the health of the forest (4) are all covered by the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram of a conventional buck DC-to-DC voltage converter. Fig. 2 is a schematic view of a DC-to-two circuit with constant current output according to the present invention. Fig. 3 is a schematic view showing a DC power conversion circuit having a constant current output according to the present invention. Μ [Main component symbol description] 10 straight k-to-DC voltage converter 102 Switching transistor 20, 30 DC power conversion circuit 22 > 32 Drive circuit 100, 200, 300 DC voltage source 202, 302 Switch 104, 204, 304, 314 Resistors 106, 206, 306 Diodes 108, 208, 308 Inductors 110, 210, 310 Capacitors 112, 212, 312 Loads 114, 214, 314 Control Signal Generator 12 200810339 116 Voltage Converter Sc Control Signals U, L2 L3 circuit GND, GND GND2 Ground terminal 2022, 2024, 2026, 3022, 3024, 3026 End point 13