201011490 九、發明說明： 【發明所屬之技術領域】 本發明係有關於一種電壓轉換器，特別是有關於一種 根據負載提供不同控制方法的電壓轉換琴。 【先前技#ί】 現今，電壓轉換器廣泛使用在不同電子產品上，例如 ❹可攜式電子產品、電腦產品等，其中電壓轉換器的轉換效 率會決定電子產品的使用時間。 脈波寬度調變（pulse width modulation，PWM)控制 器為連續時間模式之電壓轉換器的一種控制方式。如此技 藝之人士所知，脈波寬度調變控制器可產生脈波寬度調變 信號來控制耦接於電壓轉換器之輸出電感的電晶體。藉由 肩正脈波寬度調變#號之工作週期（如以CyCie)，脈波寬 度調變控制器可控制電晶體的切換狀態（即導通以及不導 參通），使得電壓轉換器能維持在特定的電壓值内。舉例來 說，當電壓轉換器的負載增加時，脈波寬度調變控制器會 增加脈波寬度調變信號之工作週期。反之，當電壓轉換器 的負载減少時’脈波寬度調變控制器會減少脈波寬度調變 信號之工作週期。 在輕載狀態（light load condition)下，雖然電壓轉換 器會維持脈波寬度調變信號操作在最小的工作週期内，然 而持續的脈波寬度調變信號容易造成耗電，因而導致電壓 轉換器的轉換效率降低。 P20080423-01/ 0975-A41726twf 6 201011490 - 因此，需要一種電壓轉換器能在輕載狀態下具有較佳 的轉換效率。 【發明内容】 本發明提供一種電壓轉換器，用以將一輸入電壓轉換· 成一輸出電壓至一負載。上述電壓轉換器包括：一輸入端， 用以接收上述輸入電壓；一輸出端，用以輸出上述輸出電 壓至上述負載；一電感，耦接於上述輸出端以及一節點之 間；一第一電晶體，耦接於上述輸入端以及上述節點之間； ❹一脈波寬度調變控制器，用以根據上述輸出電壓以及一第 一參考電壓產生一第一控制信號；一放大器，用以根據上 述輸出電壓以及一第二參考電壓產生一第二控制信號；一 偵測器，用以偵測上述負載的負載量以產生一切換信號； 以及一切換電路，用以根據上述切換信號耦接上述脈波寬 度調變控制器以及上述放大器之一者至上述第一電晶體， 其中當上述放大器耦接至上述第一電晶體時，上述切換電 路根據上述第二控制信號控制上述第一電晶體，使得上述 ❹ 第一電晶體操作在飽和區。 再者，本發明提供一種控制方法，適用於一電壓轉換 器，其中上述電壓轉換器包括一電晶體以及一電感，以及 上述電壓轉換器將上述電晶體所接收之一輸入電壓經由上 述電感轉換成一輸出電壓並輸出至一負載。上述控制方法 包括：偵測上述負載的負載量，以判斷上述電壓轉換器是 否操作在輕載狀態；當上述電壓轉換器操作在輕載狀態 時，控制上述電晶體操作在飽和區；以及當上述電壓轉換 P20080423-01/ 0975-A41726twf 7 201011490 •器操作在非輕載狀態時，控制上述電晶體操作在線性區或 是截止區。 【實施方式】 為讓本發明之上述和其他目的、特徵、和 顯易懂，下文特舉出較佳實施例，並配合所附圖式，作詳 細說明如下： • 實施例： . 第1A圖係顯示根據本發明一實施例所述之電屡轉換 器電壓轉換器100A將輸入端Nin所接收之輸入電壓v/n 轉換成輸出電壓Vout，並經由輸出端Nout將輸出電壓v。^ 提供給負載170使用。如第1A圖所顯示，電壓轉換器1〇〇°i 包括電晶體Ml、電晶體M2、電感L、脈波寬度調變（pulse width modulation，PWM)控制器 120、放大器 13〇、表考 電壓產生器140、偵測器150以及切換電路ι6〇。電晶體 _ Μ1係搞接於輸入端Nin以及節點Νι之間，而電晶體.M2 係耦接於節點N!以及接地端GND之間。電感L係輛接於 節點N!以及輸出端Nout之間。在電壓轉換器ι〇〇Α中，藉 由控制電晶體Ml以及電晶體M2的操作狀態可在電减l 感應出電流Iout’以便在輸出端N—提供輸出電壓給負 載170使用。此外’輸出電壓Vout經由電阻ri以及電阻 R2分壓後產生電壓VFB。電壓VFB會回授至電壓轉換器 100 A内以控制電晶體Ml以及電晶體M2的操作狀態，使 得輸出電壓Vout能維持在特定的電壓值内。舉例來說，輸 P20080423-01/ 0975-A41726twf 201011490 -出電壓V〇ut需維持在第一電壓值以及第二電壓值之間，其 中第一電壓值大於第二電壓值且第—電壓值以及第二電壓 值之間的電壓差可由實際應用所決定。在一實施例中，第 一電壓值大體上等於第二電壓值。 在電壓轉換器100A中，脈波寬度調變控制器12〇可根 據回授電壓VFB以及由參考電壓產生器140所提供之參考 電壓vref而產生脈波寬度調變信號PWMi以及脈波寬度調 變信號PWM2。再者，放大器130可根據回授電壓VpB以 ❼及參考電壓Vref而產生信號Verror。在此實施例中，放大器 130為誤差放大器（erroramplifier)，因此信號為類 比誤差信號。此外，在其他實施例中，參考電壓產生器 可根據不同的設計以及應用而分別提供不同之參考電壓至 脈波寬度調變控制器120以及放大器13〇。偵測器15〇可 根據回授電壓vFB、電流iout或是節點Νι上的電壓而決定 負載170的大小（即負載量）。接著，偵測器15〇可根據 所偵測到之負載170的負載量而提供切換信號sw至切換 參電路I60。接著，切換電路160可根據切換信號sw而將 放大器130耦接至電晶體Ml的控制端或是將脈波寬度調 變控制器120耦接至電晶體Ml的控制端。因此，電晶體 Ml的操作係由信號verrQr或是脈波寬度調變信號pWMi所 控制，而電晶體M2的操作係由脈波寬度調變信號PwM2 所控制。 2 在第1A圖中，當偵測器150偵測到負載17〇的負載量 增加時’即重載狀態（heavy load condition)，偵測器15〇 P2 ⑽0423-01/ 〇975-A41726twf 201011490 •所產生的切換信號SW會指示切換電路160將脈波寬度調 變控制器120耦接至電晶體M1，使得電晶體M1受到脈波 寬度调變信號PWMi的控制而操作在線性區或截止區，即 電晶體Ml為導通（turn on)或不導通（tum 〇ff)。如此 技藝之人士所知，在重載狀態下，電晶體Ml以及電晶體 M2為同步切換。舉例來說，當電晶體Μι為導通時，電晶 體M2為不導通，而當電晶體mi為不導通時，電晶體M2 為導通。此外，當偵測器15〇偵測到負載17〇的負載量減 ❹少、時，即輕载狀態（light load condition)，偵測器15〇所 產生的切換信號SW會指示切換電路16〇將放大器130耦 接至電晶體]VQ，使得電晶體Ml受到信號verr〇r的控制而 操作在飽和區。然而，在輕載狀態下，電晶體]VI2為不導 通。 ， 此外’如先前所描述’偵測器150可根據輸出電壓 V〇m、電流1。如或是節點Nl上的電壓而決定電壓轉換器 100A係操作在重載狀態或是輕載狀態。舉例來說，當負載 參170的負載量增加時，輸出電壓v_的電壓值會瞬間減少。 因此，當輸出電壓V〇ut的電壓值減少並且小於第二電壓值 時，偵測器150可根據輸出電壓V〇ut的回授電壓VpB而偵 决I到電壓轉換器1〇〇A係操作在重載狀態下。接著，偵測 器150指示切換電路16〇將脈波寬度調變控制器耦接 至電晶體M1。同時，脈波寬度調變控制器120可根據回授 電壓vFB而調整脈波寬度調變信號PWMiu及脈波寬度調 變七號PWM2的工作週期（duty cycle )以控制電晶體μ 1 Ρ20080423-01/ 〇975-A41726twf 201011490 • 以及電晶體M2的操作，姑/β， Η呆作，使得輸出電壓V〇ut能維持在第一 電壓值以及第二電壓伯> pq ,.. 值之間。相似地，當電流Iout的電流 值增加並且超過第—電流值時，偵測器150可根據電流Ut 而制到電壓轉換器⑽A係操作在重載狀態下，並指示 切換電路16G將脈波寬度觀控制器m純至電晶體 M1。此外，偵測器150亦可通知脈波寬度調變控制器120 調整脈波1度賤錢PWMi U及脈波寬度調變信號 pwm2的工作週期，使得電流w能維持在第一電流值以及 •第二電流值之間，其中第一電流值大於第二電流值且第-電流值以及第二電流值之間的電流差可由實際應用所決 定。在-實施例中，第一電流值大體上等於第二電流值。 再者¥輸出電壓V<m的電壓值增加並超過第一電壓 值時4貞別器150可根據輪出電壓乂_的回授電麗Vfb而 偵測到電壓轉換器100A係操作在輕載狀態下。接著，摘 測器150會指示切換電路16〇將放大器13〇轉接至電晶體 Ml，以提供信號V⑽r至電晶體m。相似地，當電流。 ❼的電流值減少並且小於第二電流值時，谓測器15〇可根& 電流I〇ut而偵測到電壓轉換器⑽A係操作在輕載狀態下。 第1B圖係顯示根據本發明另—實施例所述之電“壓轉 換器。在第1B圖中，偵測器15〇包括電晶體⑽、電阻 RS以及比較器152,其中比較器152為磁滞比較器。制 器150可根據節點Nl上的電壓而產生感測信號Vs，其中 感測信號Vs係對應於節點化上的電壓。接著，比較器 會比較感測信號vs以及參考電壓Vref2而產生切換信號 P20080423-01/ 0975-A41726twf 11 201011490 Γϋ先Γ描述，偵測器15G可根據節點&上的電壓 而決疋電壓轉換器100B伤 扪電壓 g 係刼作在重載狀態或是輕載妝 ^感編虎Vs增加並超過比較器152 t 時，偵測器150可偵測刭f „ 得心電壓 到電壓轉換态100B係操作在輕截 下。反之，當感測信號％減少並小於比較器152之第 二轉態電壓時’偵測器15G可偵測到電壓轉換器⑺⑽係 操作在重餘悲下’其巾第—轉態電壓係大於第二轉態電 壓。在-貫施例中’第—轉態電壓大體上等於第二轉態電 壓0 第1C圖係顯示根據本發明另一實施例所述之電屢轉 換器。相較於第1A圖中的電壓轉換器1〇〇A，電壓轉換器 100C為非同步轉換器。在電壓轉換器1〇〇c中，二極體D 係耦接於節點A以及接地端GND之間，其尹二極體D的 陽極係耦接於接地端GND，而二極體D的陰極係耦接於節 點Νι。 隨著負載的變化’本發明之電壓轉換器可選擇性地操 ❹作在低壓降模式（low drop out mode)以及脈波寬度調變 模式（PWM mode)。如前文所描述，在輕載狀態下，電 壓轉換器係操作在低壓降模式，而在非輕载狀態下，電壓 轉換器係操作在脈波寬度調變模式。因此，本發明之電壓 轉換器具有較高的轉換效率。 本發明雖以較佳實施例揭露如上，然其並非用以限定 本發明的範圍，任何熟習此項技藝者，在不脫離本發明之 精神和範圍内，當可做些許的更動與潤飾，因此本發明之 P20080423-01/ 0975-A41726twf 12 201011490 * 保護範圍當視後附之申請專利範圍所界定者為準。 '【圖式簡單說明】 第1A圖係顯示根據本發明一實施例所述之電壓轉換 第1B係顯.示根據本發明另一實施例所述之電壓轉換 器；以及 第1C係顯示根據本發明另一實施例所述之電壓轉換201011490 IX. INSTRUCTIONS: TECHNICAL FIELD The present invention relates to a voltage converter, and more particularly to a voltage conversion piano that provides different control methods according to a load. [Previous technology #ί] Today, voltage converters are widely used in different electronic products, such as portable electronic products, computer products, etc., in which the conversion efficiency of the voltage converter determines the use time of the electronic products. The pulse width modulation (PWM) controller is a control method for the voltage converter in continuous time mode. As known to those skilled in the art, the pulse width modulation controller can generate a pulse width modulation signal to control the transistor coupled to the output inductance of the voltage converter. By using the positive pulse width modulation of the shoulder period (such as CyCie), the pulse width modulation controller can control the switching state of the transistor (ie, conduction and non-conduction), so that the voltage converter can maintain Within a specific voltage value. For example, when the load of the voltage converter increases, the pulse width modulation controller increases the duty cycle of the pulse width modulation signal. Conversely, when the load on the voltage converter is reduced, the pulse width modulation controller reduces the duty cycle of the pulse width modulation signal. In the light load condition, although the voltage converter maintains the pulse width modulation signal operation in the minimum duty cycle, the continuous pulse width modulation signal is easy to cause power consumption, thus causing the voltage converter The conversion efficiency is reduced. P20080423-01/ 0975-A41726twf 6 201011490 - Therefore, there is a need for a voltage converter that has better conversion efficiency at light loads. SUMMARY OF THE INVENTION The present invention provides a voltage converter for converting an input voltage into an output voltage to a load. The voltage converter includes: an input terminal for receiving the input voltage; an output terminal for outputting the output voltage to the load; an inductor coupled between the output terminal and a node; a first power a crystal, coupled between the input end and the node; a pulse width modulation controller for generating a first control signal according to the output voltage and a first reference voltage; an amplifier for The output voltage and a second reference voltage generate a second control signal; a detector for detecting the load of the load to generate a switching signal; and a switching circuit for coupling the pulse according to the switching signal a wave width modulation controller and one of the amplifiers to the first transistor, wherein when the amplifier is coupled to the first transistor, the switching circuit controls the first transistor according to the second control signal, so that The above ❹ first transistor operates in a saturation region. Furthermore, the present invention provides a control method for a voltage converter, wherein the voltage converter includes a transistor and an inductor, and the voltage converter converts an input voltage received by the transistor into a transistor via the inductor. The output voltage is output to a load. The above control method includes: detecting a load amount of the load to determine whether the voltage converter operates in a light load state; controlling the transistor to operate in a saturation region when the voltage converter operates in a light load state; and when Voltage Conversion P20080423-01/ 0975-A41726twf 7 201011490 • When the device is operated in a non-light load state, the above transistor is controlled to operate in the linear region or the cutoff region. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features, and aspects of the present invention are set forth in the <RTIgt; It is shown that the electrical converter voltage converter 100A according to an embodiment of the present invention converts the input voltage v/n received by the input terminal Nin into an output voltage Vout, and outputs the voltage v via the output terminal Nout. ^ Provided to load 170 for use. As shown in FIG. 1A, the voltage converter 1〇〇°i includes a transistor M1, a transistor M2, an inductor L, a pulse width modulation (PWM) controller 120, an amplifier 13〇, and a meter voltage. The generator 140, the detector 150, and the switching circuit ι6〇. The transistor _ Μ1 is connected between the input terminal Nin and the node ,1, and the transistor M2 is coupled between the node N! and the ground GND. The inductor L is connected between the node N! and the output terminal Nout. In the voltage converter ι, by controlling the operating states of the transistor M1 and the transistor M2, the current Iout' can be induced in the electrical deduction to provide an output voltage to the load 170 at the output terminal N. Further, the output voltage Vout is divided by the resistor ri and the resistor R2 to generate a voltage VFB. The voltage VFB is fed back into the voltage converter 100 A to control the operating states of the transistor M1 and the transistor M2 so that the output voltage Vout can be maintained within a specific voltage value. For example, the input voltage P20080423-01/ 0975-A41726twf 201011490 - the output voltage V〇ut needs to be maintained between the first voltage value and the second voltage value, wherein the first voltage value is greater than the second voltage value and the first voltage value and The voltage difference between the second voltage values can be determined by the actual application. In an embodiment, the first voltage value is substantially equal to the second voltage value. In the voltage converter 100A, the pulse width modulation controller 12A can generate the pulse width modulation signal PWMi and the pulse width modulation according to the feedback voltage VFB and the reference voltage vref provided by the reference voltage generator 140. Signal PWM2. Furthermore, the amplifier 130 can generate the signal Verror based on the feedback voltage VpB and the reference voltage Vref. In this embodiment, amplifier 130 is an error amplifier, so the signal is an analog error signal. Moreover, in other embodiments, the reference voltage generator can provide different reference voltages to the pulse width modulation controller 120 and the amplifier 13A, respectively, depending on the design and application. The detector 15A determines the size of the load 170 (i.e., the amount of load) based on the feedback voltage vFB, the current iout, or the voltage on the node Ν. Then, the detector 15A can provide the switching signal sw to the switching parameter circuit I60 according to the detected load amount of the load 170. Then, the switching circuit 160 can couple the amplifier 130 to the control end of the transistor M1 or the pulse width modulation controller 120 to the control end of the transistor M1 according to the switching signal sw. Therefore, the operation of the transistor M1 is controlled by the signal verrQr or the pulse width modulation signal pWMi, and the operation of the transistor M2 is controlled by the pulse width modulation signal PwM2. 2 In Figure 1A, when the detector 150 detects an increase in the load of the load of 17 ', that is, the heavy load condition, the detector 15 〇 P2 (10) 0423-01 / 〇 975-A41726twf 201011490 • The generated switching signal SW instructs the switching circuit 160 to couple the pulse width modulation controller 120 to the transistor M1 such that the transistor M1 is controlled by the pulse width modulation signal PWMi to operate in the linear region or the cutoff region. That is, the transistor M1 is turned on or off (tum 〇 ff). As is known to those skilled in the art, in the heavy load state, the transistor M1 and the transistor M2 are switched synchronously. For example, when the transistor 为ι is turned on, the transistor M2 is non-conductive, and when the transistor mi is non-conductive, the transistor M2 is turned on. In addition, when the detector 15 detects that the load of the load 17 ❹ is reduced, that is, the light load condition, the switching signal SW generated by the detector 15 指示 indicates the switching circuit 16 〇 The amplifier 130 is coupled to the transistor [VQ] such that the transistor M1 is operated in the saturation region under the control of the signal verr〇r. However, in the light load state, the transistor] VI2 is non-conductive. In addition, the detector 150 can be based on the output voltage V〇m, current 1, as previously described. For example, the voltage on the node N1 determines whether the voltage converter 100A operates in a heavy load state or a light load state. For example, when the load of the load parameter 170 increases, the voltage value of the output voltage v_ decreases instantaneously. Therefore, when the voltage value of the output voltage V〇ut decreases and is less than the second voltage value, the detector 150 can detect the I to the voltage converter according to the feedback voltage VpB of the output voltage V〇ut. Under heavy load conditions. Next, the detector 150 instructs the switching circuit 16 to couple the pulse width modulation controller to the transistor M1. At the same time, the pulse width modulation controller 120 can adjust the pulse width modulation signal PWMiu and the pulse width modulation PWM2 duty cycle according to the feedback voltage vFB to control the transistor μ 1 Ρ20080423-01 / 〇975-A41726twf 201011490 • And the operation of the transistor M2, / / β, Η ,, so that the output voltage V 〇 ut can be maintained between the first voltage value and the second voltage > pq, .. value. Similarly, when the current value of the current Iout increases and exceeds the first current value, the detector 150 can be made to the voltage converter according to the current Ut (10). The system operates in the heavy load state, and instructs the switching circuit 16G to set the pulse width. The controller m is pure to the transistor M1. In addition, the detector 150 can also notify the pulse width modulation controller 120 to adjust the duty cycle of the pulse wave 1 degree PWMi U and the pulse width modulation signal pwm2, so that the current w can be maintained at the first current value and Between the second current values, wherein the first current value is greater than the second current value and the current difference between the first current value and the second current value can be determined by actual application. In an embodiment, the first current value is substantially equal to the second current value. Furthermore, when the voltage value of the output voltage V<m increases and exceeds the first voltage value, the 4 discriminator 150 can detect that the voltage converter 100A operates at a light load according to the feedback voltage Vfb of the turn-on voltage 乂_ In the state. Next, the stalker 150 instructs the switching circuit 16 to switch the amplifier 13 至 to the transistor M1 to provide the signal V(10)r to the transistor m. Similarly, when the current. When the current value of ❼ decreases and is less than the second current value, the detector 15 detects the voltage converter (10) A and operates in a light load state. Figure 1B shows an electrical "voltage converter" according to another embodiment of the present invention. In Figure 1B, the detector 15A includes a transistor (10), a resistor RS, and a comparator 152, wherein the comparator 152 is magnetic The comparator 150 can generate the sensing signal Vs according to the voltage on the node N1, wherein the sensing signal Vs corresponds to the voltage on the nodeization. Then, the comparator compares the sensing signal vs and the reference voltage Vref2 The switching signal is generated P20080423-01/ 0975-A41726twf 11 201011490 Firstly, the detector 15G can determine the voltage of the voltage converter 100B according to the voltage on the node & When the loader feels that the Vs is increased and exceeds the comparator 152 t, the detector 150 can detect the 刭f „ the voltage to the voltage transition state 100B is operated at a light cut. Conversely, when the sense signal % decreases and is less than the second transition voltage of the comparator 152, the detector 15G can detect that the voltage converter (7) (10) operates under the sorrow of the sorrow. The second transition voltage. In the embodiment, the -th transition voltage is substantially equal to the second transition voltage. The first embodiment shows an electrical repeater according to another embodiment of the present invention. The voltage converter 100C is a non-synchronous converter compared to the voltage converter 1A in Figure 1A. In the voltage converter 1〇〇c, the diode D is coupled between the node A and the ground GND, the anode of the Yin diode D is coupled to the ground GND, and the cathode of the diode D The system is coupled to the node Νι. As the load changes, the voltage converter of the present invention can be selectively operated in a low drop out mode and a PWM mode. As described earlier, in the light load state, the voltage converter operates in a low drop mode, while in the non-light load state, the voltage converter operates in a pulse width modulation mode. Therefore, the voltage converter of the present invention has a high conversion efficiency. The present invention has been described above with reference to the preferred embodiments thereof, and is not intended to limit the scope of the present invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. P20080423-01/ 0975-A41726twf 12 201011490 of the present invention * The scope of protection is subject to the definition of the scope of the patent application. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a diagram showing a voltage conversion according to an embodiment of the present invention, showing a voltage converter according to another embodiment of the present invention; and a first C-system display according to the present invention. Voltage conversion according to another embodiment of the invention
【主要元件符號說明】 100A、100B〜電壓轉換器 12 0〜脈波寬度調變控制器 130〜放大器 140〜參考電壓產生器 150〜偵測器 152〜比較器 160〜切換電路 Π0〜負載 D〜二極體 GND〜接地端 I〇ut〜電流 L〜電感 Ml、M2、MS〜電晶體 Νι、N2〜節點 Nin〜輸入端 Ν_〜輸出端 PWM!、PWM2〜脈波寬度調變信號 Rl、R2、RS〜電阻 SW〜切換信號 Vemn·〜信號 VpB〜電壓 vin〜輸入電壓 VQUt〜輸出電壓 vref〜參考電壓 vs〜感測信號 P20080423-01/ 0975-A41726twf 13[Description of main component symbols] 100A, 100B to voltage converter 12 0 to pulse width modulation controller 130 to amplifier 140 to reference voltage generator 150 to detector 152 to comparator 160 to switching circuit Π 0 to load D 〜 Diode GND~ Ground Terminal I〇ut~ Current L~Inductance Ml, M2, MS~Transistor Νι, N2~Node Nin~ Input Ν_~ Output PWM!, PWM2~ Pulse Width Modulation Signal Rl, R2 , RS ~ resistance SW ~ switching signal Vemn · ~ signal VpB ~ voltage vin ~ input voltage VQUt ~ output voltage vref ~ reference voltage vs ~ sensing signal P20080423-01 / 0975-A41726twf 13