1301936 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種電壓調節器，尤其關於一種可在負 載瞬間變化時維持穩定的輸出電壓之電壓調節器。 【先前技術】 圖1(A)顯示習知的線性調節器u之第_例子之電路 圖。線性調節器11將輸入電壓Vin轉換成輪出電壓vQut 並且依據負載id之需求而供應輸出電流I〇ut。由電阻R1 與R2所構成的電阻性分壓器產生一回授電壓Vfb，其代表 輸出電壓v〇ut。藉由比較回授電壓Vfb與一預定的參考電 壓Vref，誤差放大器13產生並施加一誤差電壓至電晶 體PQ之閘極。電晶體PQ之汲極源極電流通道係連接於 輸入電壓vin與輸出電壓VQut間。藉由施加誤差電壓 以控制汲極源極電流通道之電阻值，線性調節器u使輸 出電壓Vout維持於一調節值且依據負載“之需求而供應輸 出電流Iout。設置於輸入電壓Vin與輸出電壓間之作為 被動元件之電晶體PQ亦得由NM〇s電晶體NQK替代， 如圖1 (B)之習知的線性調節器丨2之第二例子所示。只不 過在此情況下，誤差放大器13之非反相輸入端係改成接 收參考電壓vref而其反相輸入端則改成接收回授電壓Vfb。 當負載Id瞬間下降，例如突然移除負載Id時，在輸出 電流lout回應此一瞬間變化而最終降低至等於負載Id之 刚，輸出電流Iout中之多餘部分會轉而對輸出電容c〇ut充 ⑧ 5 1301936 ^ ^致輸出電壓V°ut上升而脫離原先的調節值。為了解 " 問題，白知技藝建議一種電流排放電路，用以於負 載瞬間夂化0^對於輸出電流中之多餘部分提供一排放 路徑，藉以抑制輸出電壓vout之上升。 在圖1(A)之第一例子中，電流排放電路i4a主要具有 :電壓比較器15與-電晶體開關PS。如前所述當負載Id 瞬間下降而造成輸出電· v_上升時，誤差放大器。也 因而產生一上升的誤差電壓ν_。一旦誤差電壓v…超過 一預定的觸發電壓Vtrg時，電壓比較器15將導通電晶體 開關PS，以便形成一排放路徑使輸出電流直接流入地 面電位。在圖1(B)之第二例子中，電流排放電路14b中之 電壓比較為1 5則改換成直接比較回授電壓與參考電壓 Vref ’其中回授電壓vfb必須先經過一預定的補償電壓v。^ 之調整。當回授電壓Vfb過大而觸發電壓比較器15時，電 晶體開關NS被導通以便形成一排放路徑使輸出電流 直接流入地面電位。 雖然圖1 (A)或1 (B)所示之習知技術皆可利用電流排 放電路14a或14b形成一排放路徑而抑制輸出電壓之 上升，但由於電晶體開關PS或NS導通時，線性調節器 11或12之輸出端幾乎直接短路於地面電位，造成輸出電 流I〇ut劇烈地降低。結果’輸出電壓VQut非常容易發生劇 烈地上下震盪，使得電流排放電路14a或14b重複地啟動 和關閉電晶體開關PS或NS。 6 1301936 【發明内容】 述問題，本發明之一目的在於提供一種電壓 以^ 載瞬間變化時防止過電壓與輪出震盡，藉 提仏一穩定的輪出電壓。 依據本發明之電壓轉換電路具有一電壓轉換電路、一 一：偵測電路、以及一電流排放電路。電壓轉換電路具有 、雨出端，用以於一輸出電壓下供應一輪出電流至一負 载。事件谓測電路偵測該負載之一瞬間t化事彳。回應於 該負載之該瞬間變化事件，電流排放電路允許一電流源提 排放電流從該電壓轉換電路之該輸出端流入二地 '面 =位。該排放電流係有限且穩定。當輸出電壓下降至一預 定的臨界電壓時，電流排放電路允許該電流源繼續於一延 長時間.内提供該有限且敎的排放電流，以使輪出電壓從 ^界電壓下降至一調節值。BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a voltage regulator, and more particularly to a voltage regulator that maintains a stable output voltage when a load transient changes. [Prior Art] Fig. 1(A) shows a circuit diagram of a first example of a conventional linear regulator u. The linear regulator 11 converts the input voltage Vin into the wheel-out voltage vQut and supplies the output current I〇ut according to the demand of the load id. A resistive voltage divider formed by resistors R1 and R2 produces a feedback voltage Vfb which represents the output voltage v〇ut. The error amplifier 13 generates and applies an error voltage to the gate of the electric crystal PQ by comparing the feedback voltage Vfb with a predetermined reference voltage Vref. The drain source current path of the transistor PQ is connected between the input voltage vin and the output voltage VQut. By applying an error voltage to control the resistance value of the drain source current channel, the linear regulator u maintains the output voltage Vout at an adjustment value and supplies the output current Iout according to the demand of the load. The input voltage Vin and the output voltage are set. The transistor PQ, which is a passive component, is also replaced by the NM〇s transistor NQK, as shown in the second example of the conventional linear regulator 丨2 of Fig. 1(B). However, in this case, the error The non-inverting input of the amplifier 13 is changed to receive the reference voltage vref and its inverting input is changed to receive the feedback voltage Vfb. When the load Id drops instantaneously, for example, the load Id is suddenly removed, the output current lout responds to this. After a momentary change and finally reduced to equal the load Id, the excess part of the output current Iout will turn to the output capacitor c〇ut charge 8 5 1301936 ^ ^, causing the output voltage V°ut to rise away from the original adjustment value. Understand the problem, the white knowing technique suggests a current drain circuit for instantaneously decompressing the load. 0^ provides a drain path for the excess portion of the output current, thereby suppressing the output voltage vout. In the first example of Fig. 1(A), the current discharge circuit i4a mainly has a voltage comparator 15 and a transistor switch PS. As described above, when the load Id instantaneously drops, the output power v_ rises. The error amplifier also produces a rising error voltage ν_. Once the error voltage v... exceeds a predetermined trigger voltage Vtrg, the voltage comparator 15 conducts the crystal switch PS to form a discharge path to direct the output current directly to the ground. In the second example of Fig. 1(B), the voltage comparison in the current discharge circuit 14b is changed to 15 to be directly compared with the feedback voltage and the reference voltage Vref. The feedback voltage vfb must first pass a predetermined When the feedback voltage Vfb is too large to trigger the voltage comparator 15, the transistor switch NS is turned on to form a discharge path to directly output the output current to the ground potential. Although FIG. 1(A) or 1 ( The conventional technique shown in B) can use the current discharge circuit 14a or 14b to form a discharge path to suppress the rise of the output voltage, but since the transistor switch PS or NS is turned on, the linear regulator 11 The output of 12 is almost directly short-circuited to the ground potential, causing the output current I〇ut to drastically decrease. As a result, the output voltage VQut is very likely to violently oscillate up and down, so that the current discharge circuit 14a or 14b repeatedly turns on and off the transistor switch PS. Or NS. 6 1301936 SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a voltage that can prevent overvoltage and wheeling from being shaken when a load is instantaneously changed, thereby providing a stable wheeling voltage. The voltage conversion circuit has a voltage conversion circuit, a detection circuit, and a current discharge circuit. The voltage conversion circuit has a rain output terminal for supplying one round of current to a load at an output voltage. The event predicate circuit detects that one of the loads is instantaneous. In response to the momentary change event of the load, the current drain circuit allows a current source to draw a discharge current from the output of the voltage conversion circuit to the 'ground' position. This emission current is limited and stable. When the output voltage drops to a predetermined threshold voltage, the current drain circuit allows the current source to continue for a long period of time to provide the limited and helium discharge current to cause the wheel-out voltage to drop from the boundary voltage to a regulated value.
【實施方式】 下文中之說明與附圖將使本發明之前述與其他目 的、特徵、與優點更明顯。茲將參照圖式詳細說明依 發明之較佳實施例。 圖2(A)顯示依據本發明之電壓調節器2〇之電路區塊 圖。參照圖2(A)’電壓調節器2〇主要包括一電壓轉換電 路21、一事件偵測電路22、以及一電流排放電路23。'電 流排放電路23主要包括一放電控制電路24與一可開關的 電流源25。 ⑧ 1301936 簡單來說，電壓轉換電路21係將輸入電壓Vin轉換成 輸出電壓Vout’並且依據負載Id之需求而於一輸出端供應 輸出電流I〇ut。電壓轉換電路21得由圖1(A)或1(B)所示之 線性調節器11或12所實施，亦即主要包括一分壓電路、 一誤差放大器、與一作為被動元件之電晶體所組成。此 外，電壓轉換電路21亦得由採用脈衝寬度調變（pWM)或 脈衝頻率調變（PFM)等技術所控制之切換式調節器 (Switching Regulator)所實施。又或者，電壓轉換電路η 亦=由電荷泵（Charge Pump)調節器所實施。不論是切換式 調節器或電荷泵調節器’均為熟習此項技藝之人士所熟 悉，故此處省略其電路與操作之詳細說明。 、 、事件價測電路22係' 用以偵測負載瞬間變化之事件， 尤其用以偵測負載Id從重負載瞬間變化至輕負載之事 件。如前所述，當負葡T Μ舌 4 、 重負載瞬間變化至輕負載時， =壓L會因輸出電容C_之充電而上升，所以事件 "ί貞測電路22得由一 f ^ ^ ^ + 雷Μν β/ ㈣比較電路所實施，用以偵測輸出 於山+ ^ 疋的界電壓vth。除了直接偵測 輸出電壓vout以外，事件 、 壓V m k 事件偵電路22亦可偵測與輸出電 壓〜，此兩著皆隨著輪出電二’差電或回授電 事件偵測電路22得v_而變化。舉例而言， 施，藉由比較誤差;壓：： 負載瞬間變化之事侏 觸發電壓、而有效地獲知 圖1W所示之電壓樣地’事件偵測電路22亦得由 車又益I5所實施，藉由比較回授電壓 ⑧ 8 1301936The foregoing and other objects, features and advantages of the present invention will become apparent from DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the invention will be described in detail with reference to the drawings. Figure 2 (A) shows a circuit block diagram of a voltage regulator 2 in accordance with the present invention. Referring to Fig. 2(A), the voltage regulator 2A mainly includes a voltage conversion circuit 21, an event detecting circuit 22, and a current discharging circuit 23. The current discharge circuit 23 mainly includes a discharge control circuit 24 and a switchable current source 25. 8 1301936 Briefly, the voltage conversion circuit 21 converts the input voltage Vin into an output voltage Vout' and supplies an output current I〇ut at an output according to the demand of the load Id. The voltage conversion circuit 21 is implemented by the linear regulator 11 or 12 shown in FIG. 1(A) or 1(B), that is, mainly includes a voltage dividing circuit, an error amplifier, and a transistor as a passive component. Composed of. In addition, the voltage conversion circuit 21 is also implemented by a switching regulator controlled by a technique such as pulse width modulation (pWM) or pulse frequency modulation (PFM). Alternatively, the voltage conversion circuit η is also implemented by a charge pump regulator. Whether a switch regulator or a charge pump regulator is well known to those skilled in the art, detailed descriptions of its circuitry and operation are omitted herein. The event price measurement circuit 22 is used to detect an event of a transient change in the load, and is particularly useful for detecting an event in which the load Id changes instantaneously from a heavy load to a light load. As mentioned above, when the negative Portuguese T tongue 4 and the heavy load change instantaneously to a light load, the voltage L will rise due to the charging of the output capacitor C_, so the event < 贞 电路 circuit 22 has a f ^ ^ ^ + Thunder ν β / (d) The comparison circuit is implemented to detect the boundary voltage vth outputted in the mountain + ^ 。. In addition to directly detecting the output voltage vout, the event, voltage Vmk event detection circuit 22 can also detect and output the voltage ~, both of which are obtained by the wheel two-difference or the feedback event detection circuit 22 V_ changes. For example, by comparing the error; the pressure:: the instantaneous change of the load, the trigger voltage, and effectively knowing the voltage sample shown in FIG. 1W, the event detection circuit 22 is also implemented by the vehicle Yiyi I5. By comparing the feedback voltage 8 8 1301936
Vfb(含補償電壓v〇fs)與參考電壓Vref而有效地獲知負載瞬 間變化之事件。Vfb (including the compensation voltage v〇fs) and the reference voltage Vref effectively know the event of the load transient change.
回應於事件偵測電路22所偵測到的負載瞬間變化， 放電控制電路24產生一放電控制信號DP，用以控制可開 關的電流源25。具體而言，當輸出電壓Vout超過一預定的 臨界電壓Vth時，放電控制信號DP啟動（或導通）可開關的 電流源25，用以允許一排放電流Isk從電壓轉換電路2 1之 端排放至一地面電位。然而，當輸出電壓因排放 私机Isk之作用而下降至低於臨界電壓乂化時，放電控制信 開始延伸一段預定的時間，用以繼續允許可開關的 屯机源25提供排放電流Isk，以便輸出電壓得以繼續 下=而恢復至負載瞬間變化前之調節值。請注意可開關的 ^ l原25在啟動（或導通）後係提供一有限且穩定的排放 sk而非讓電壓轉換電路21之輸出端直接短路於地 面電位，因而達成穩定地降低輸出電壓，避免震盪發 生。 圖2(B)顯示依據本發明之電壓調節器2〇之操作時7 =在，間T0 ’負載Id從重負載Ihy瞬間下降至輕負載Ilt 、輸出電机Iout因無法立即反應而轉變成電容電流込 對於輸出電谷c—充電。因此，輸出電壓從時間τ ，始上升。輸出電壓V〇ut在時間T1達到一預定的臨界, f二後、，事件雜路22受觸發而啟動電流排放電, 日士門延小段因實際電路之有限的操作速度而造成合 日〇仏遲後，T開關的電流源25確實於時間τ2開啟㈡ 9 1301936 導通）而提供一有限且穩定的排放電流Isk。結果，電容電 流Ic轉變成對於輸出電容cout放電，亦即如圖所示其電流 方向由正（+ )轉負（―）。在時間T3，輸出電壓下降至 6¾界電C Vth ’但凊注意排放電流仍繼續由可開關的電 流源25提供，並未中止。排放電流Isk從時間τ3持續供 •應至時F曰 1 Τ4，使得輸出電壓v〇ut得以從臨界電壓、恢復 至原先的調節值V。。換言之，電流排放電路23所提供之 _排放電流Isk係設計成在輸出電壓恢復至原先的調節 值V。時才結束。兹合理假設在時間T3至T4間，排放電 流Isk主要係用於排除輸出電容c〇ut中所儲存的多餘電 何，亦即此時輸出電流I〇ut已經大致回應於負載瞬間變化 而凋整/到t負載ilt。因此，倘若在一實施例中電流排放電 路23係提供一固定的排放電流，則此延長時間可計 异如下·· dT = Cout/Isk*(vth- V。）。 圖3顯示依據本發明之電壓調節器之一例子3 〇之詳 φ 細電路圖。在電壓轉換電路31中，電晶體P1與P2以及 電流鏡Ml、M2、與M3共同構成一差動放大對，用以比 • 軚回授電壓Vfb與參考電壓Vfef，並且產生誤差電壓乂…In response to an instantaneous change in the load detected by the event detecting circuit 22, the discharge control circuit 24 generates a discharge control signal DP for controlling the switchable current source 25. Specifically, when the output voltage Vout exceeds a predetermined threshold voltage Vth, the discharge control signal DP activates (or turns on) the switchable current source 25 to allow an emission current Isk to be discharged from the end of the voltage conversion circuit 2 1 to A ground potential. However, when the output voltage drops below the threshold voltage due to the action of the discharge private machine Isk, the discharge control signal begins to extend for a predetermined period of time to continue to allow the switchable source 25 to provide the discharge current Isk, so that The output voltage continues to go down = and returns to the adjusted value before the load changes instantaneously. Please note that the switchable 25 provides a limited and stable discharge sk after startup (or conduction) instead of directly shorting the output of the voltage conversion circuit 21 to the ground potential, thus achieving a stable reduction of the output voltage and avoiding The shock occurred. Fig. 2(B) shows the operation of the voltage regulator 2〇 according to the present invention. 7 = at, between, T0 'load Id instantaneously drops from the heavy load Ihy to the light load Ilt, and the output motor Iout is converted into a capacitive current due to the inability to react immediately.込 For the output battery c—charge. Therefore, the output voltage rises from time τ. The output voltage V〇ut reaches a predetermined threshold at time T1. After f2, the event hybrid 22 is triggered to start current discharge, and the small section of the Japanese gate is caused by the limited operating speed of the actual circuit. After a delay, the current source 25 of the T-switch is indeed turned on at time τ2 (2) 9 1301936 turns on) to provide a limited and stable discharge current Isk. As a result, the capacitor current Ic is converted to discharge for the output capacitor cout, that is, its current direction is changed from positive (+) to negative (-) as shown. At time T3, the output voltage drops to 63⁄4 boundary C Vth ' but note that the discharge current continues to be supplied by the switchable current source 25 and is not aborted. The discharge current Isk is continuously supplied from time τ3 to F曰 1 Τ4, so that the output voltage v〇ut can be restored from the threshold voltage to the original adjustment value V. . In other words, the _ discharge current Isk supplied from the current discharge circuit 23 is designed to return to the original adjustment value V at the output voltage. It only ends. It is reasonable to assume that between time T3 and T4, the discharge current Isk is mainly used to eliminate the excess electricity stored in the output capacitor c〇ut, that is, the output current I〇ut has been roughly responsive to the transient change of the load. / to t load ilt. Therefore, if the current discharge circuit 23 provides a fixed discharge current in an embodiment, the extension time can be calculated as follows: dT = Cout / Isk * (vth - V.). Fig. 3 is a view showing a detailed circuit diagram of an example of a voltage regulator according to the present invention. In the voltage conversion circuit 31, the transistors P1 and P2 and the current mirrors M1, M2, and M3 together form a differential amplification pair for the feedback voltage Vfb and the reference voltage Vfef, and generate an error voltage 乂...
* 來控制设置於輸入電壓Vin與輸出電壓v〇ut間之電晶體PQ 之電流通道導通電阻。因此，電壓轉換電路3丨係由一線 性調節器所實施。 “在事件偵測電路3 2中，藉由電流鏡對稱設計，透過 T晶體N3可產生一電流Ia，其係與流經差動放大對之電 曰曰體P 1之電流成線性比例關係，並且透過電晶體P3可產 1301936* To control the current path on-resistance of the transistor PQ set between the input voltage Vin and the output voltage v〇ut. Therefore, the voltage conversion circuit 3 is implemented by a linear regulator. "In the event detection circuit 32, by the current mirror symmetrical design, a current Ia is generated through the T crystal N3, which is linearly proportional to the current flowing through the differential amplifier pair P 1 . And through the transistor P3 can produce 1301936
生另一電流Ib，其係與流經差動放大對之電晶體P2之電 流成線性比例關係。由於差動放大對係依據回授電壓Vfb 與參考電壓Vref而分配流經電晶體P1與P2之電流，故電 流Ia與電流Ib間之差異可適當地反應出回授電壓Vfb與參 考電壓Vref間之差異。當電流Ib與電流Ia間之誤差電流Ierr 超過一預定的補償電流I〇fs時，史米特觸發器（Schmidt Trigger)STl被觸發。因此，事件偵測電路32得視為一電 流比較器’利用電流比較方式來偵測負載瞬間變化之事 在史米特觸發器S T1被觸發而輸出一低位準後，放電 控制電路34之電晶體P4導通而電晶體N4不導通，因此 一充電電流經由電晶體P4對於電容C3充電。很快地，電 容C3上之電壓足夠大而觸發史米特觸發器ST2，因而放 電控制信號DP進入低位準狀態。回應於低位準狀態的放 電控制信號DP，可開關的電流源35之開關電晶體PS導 通，允許電流源cc提供一有限且穩定的排放電流isk。在 一實施例中，電流源CC可設計為一固定的電流源，使得 排放電流Isk為固定值。當事件偵測電路32之史米特觸發 器S T1之輸出從低位準轉換回高位準時，亦即輸出電壓 Vout已經因排放電流Isk而下降至臨界電壓vth，放電控制 電路34之電晶體P4變成不導通而電晶體N4變成導通。 結果’電容C3經由電阻R3與電晶體N4而放電。因為電 阻R3之存在造成電容C3之放電速率比先前的充電速率還 慢，所以放電控制信號DP會延長一段時間dT後才轉態成Another current Ib is generated which is linearly proportional to the current flowing through the transistor P2 of the differential amplification pair. Since the differential amplification pair distributes the current flowing through the transistors P1 and P2 according to the feedback voltage Vfb and the reference voltage Vref, the difference between the current Ia and the current Ib can appropriately reflect the feedback voltage Vfb and the reference voltage Vref. The difference. When the error current Ierr between the current Ib and the current Ia exceeds a predetermined compensation current I〇fs, the Schmidt Trigger ST1 is triggered. Therefore, the event detection circuit 32 is regarded as a current comparator's use of the current comparison method to detect the instantaneous change of the load. After the Schmitt trigger S T1 is triggered to output a low level, the discharge control circuit 34 is powered. The crystal P4 is turned on and the transistor N4 is not turned on, so a charging current charges the capacitor C3 via the transistor P4. Soon, the voltage on capacitor C3 is large enough to trigger the Schmitt trigger ST2, and thus the discharge control signal DP enters a low level state. In response to the discharge control signal DP of the low level state, the switching transistor PS of the switchable current source 35 is turned on, allowing the current source cc to provide a limited and stable discharge current isk. In one embodiment, the current source CC can be designed as a fixed current source such that the discharge current Isk is a fixed value. When the output of the Schmitt trigger S T1 of the event detecting circuit 32 is switched from the low level to the high level, that is, the output voltage Vout has dropped to the threshold voltage vth due to the discharging current Isk, the transistor P4 of the discharging control circuit 34 becomes The transistor N4 becomes conductive without being turned on. As a result, the capacitor C3 is discharged via the resistor R3 and the transistor N4. Since the discharge rate of the capacitor C3 is slower than the previous charging rate due to the presence of the resistor R3, the discharge control signal DP is extended for a period of time dT before being converted into a state.
11 1301936 為高位準而終止可開關的電流源35之排放電流Isk。 ;、二本表明業已藉由較佳實施例作為例示加以說 月應瞭解者為：本發明不限於此被揭露的實施例。相反 地’本發明意欲涵蓋對於熟習此項技藝之人士而言係明顯 H #㈣相似配置H中請專利範圍之範圍應根 據束廣的绘釋，以包容所有此類修改與相似配置。 【圖式簡單說明】 圖1 (A)顯示習知的線性調節器一 m ^ 弟一例子之電路圖。 θ 1 (B),、、、頁不篇知的線性調節器 in ?^ΔΜε - ^ 昂一例子之電路圖。 =2⑷顯不依據本發明之電壓調 = 圖_顯示依據本發明之電壓調節^路^塊圖。 圖3顯示依據本發明之電壓。 呆作¥序圖。 路圖。 盗之一例子之詳細雷 【主要元件符號說明】 11，12 線性調節器 13 誤差放大器 14a，14b 電流排放電路 15 電壓比較器 2〇, 30 電壓調節器 2 1，3 1 電壓轉換電路 22, 32 事件偵測電路 23 電流排放電路 12 130193611 1301936 Terminates the discharge current Isk of the switchable current source 35 for a high level. The present invention has been described by way of example of a preferred embodiment. It should be understood that the invention is not limited to the disclosed embodiments. Rather, the invention is intended to be encompassed by persons skilled in the art. H #(四) Similar Configuration The scope of the patent scope should be based on a broad description of the scope of the invention to accommodate all such modifications and similar configurations. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1(A) shows a circuit diagram of a conventional linear regulator. θ 1 (B),,,, page, unknown linear regulator in ?^ΔΜε - ^ An example of the circuit diagram. = 2 (4) A voltage adjustment according to the present invention is shown = Figure _ shows a voltage regulation diagram according to the present invention. Figure 3 shows the voltage in accordance with the present invention. Stay in the order of ¥. Road map. The details of one example of piracy [main component symbol description] 11,12 linear regulator 13 error amplifier 14a, 14b current discharge circuit 15 voltage comparator 2 〇, 30 voltage regulator 2 1,3 1 voltage conversion circuit 22, 32 Event detection circuit 23 current discharge circuit 12 1301936
24, 34 放電控制電路 25, 35 可開關的電流源 C 〇 ut 輸出電容 cc 電流源 DP 放電控制信號 Rl，R2 電阻 ST1，ST2 史米特觸發器 Ml 〜M3 電流鏡 I 0 u t 輸出電流 Id負 載 ic 電容電流24, 34 Discharge control circuit 25, 35 Switchable current source C 〇ut Output capacitor cc Current source DP Discharge control signal Rl, R2 Resistance ST1, ST2 Schmitt trigger Ml ~ M3 Current mirror I 0 ut Output current Id load Ic capacitor current
I hy 重 負 載 lit 輕 負 載 I s k 排 放 電 流 I e r r 誤 差 電 流 I o f s 補 償 電 流 Vin 入 電 壓 Vout 輸 出 電 壓 vfb 回 授 電 壓 Verr 誤 差 電 壓 V〇fs 補 償 電 壓 vth 臨 界 電 壓 dT 延 長 時 間 13I hy heavy load lit light load I s k discharge current I e r r error current I o f s compensation current Vin input voltage Vout output voltage vfb feedback voltage Verr error voltage V〇fs compensation voltage vth critical voltage dT extension time 13