200828800 九、發明說明： - 【發明所屬之技術領域】 - 本發明涉及一種電源裝置，特別涉及一種電源軟啟動 裝置。 【先前技術】 開關電源以其體積小、性能好和使用方便的特點，在 通訊、網路、工業控制和消費性電子產品等領域得到廣泛 广應用。開關電源在電路中用於為電路的工作提供電能，是 "電路工作最基礎的要求。 開關電源的輸入電路通常採用電橋整流加電容濾波的 形式。在輸入電路合閘瞬間，由於輸入濾波電容的初始電 壓為零，輸入濾波電容迅速充電，形成很大的瞬時衝擊電 流，也稱為浪湧電流，該衝擊電流遠大於穩態輸入電流。 如圖1所示，大功率開關電源輸入採用較大容量的濾波電 容，其衝擊電流可達100A。在開關電源接通的瞬間:如此 C.大的衝擊電流往往會導致後續電路的損壞，如濾波電容， 造成開關電源無法正常工作。因此，開關電源中需設置防 止衝擊電流的軟啟動電路，以保證開關電源的正常可靠的 運行。 如圖2所示，其為傳統的採用熱敏電阻的軟啟動電 路。熱敏電阻R1的-端與整流器D1的正輸出端相連，熱 敏電阻R1的另一端與電解電容C1的正極相連，電解電容 的負極與整流器01的負輸出端相連。交流電藉由整流 器D1整流為直流電後，藉由熱敏電阻Rl給電解電容以 200828800 充電。熱敏電阻R1具有倉溫痄在杳冬μ ^ 貝度係數特性，其電阻值隨著 溫度的升高而迅速減小，因此在電源接通的瞬間，敎敏電 阻R1的阻值較大，起到限制衝擊電流的作用。隨著流過 熱敏電阻R1電流量逐漸增加，熱敏電阻Ri溫度升高，其 阻值則變小，電路趨於正常工作狀態。然而採用熱敏電阻 R1防止衝擊電流-般適用於小功率開關電源。由於熱敏電 阻R1的熱慣性，重新恢復高阻值狀態需要一定時間。所 以，當電源斷電後又需要很快接通的情況，便起不到限制 衝擊電流的作用。此外，實際工作中，熱敏電阻以容易 被燒壞，整個電路無法工作。 【發明内容】 有鑒於此，有必要提供一種穩定的電源軟啟動裝置。 一種電源軟啟動裝置包括電源輸入端、分壓調節電 路、第一延時電路、第一開關電路、第二延時電路、第二 開關電路和電源輸出端，該分壓調節電路用於將來自該電 源輸入端的輸入電流導向該第一延時電路，並為該第一開 關電路提供第-開啟電壓；該第一延時電路用於接收該輸 入電流進行延時動作；該第一開關電路用於在該第一延時 電路延時動作完成|，接收該第一開啟電壓並打開，同時 將該輸入電流導向該第二延時電路並為該第二開關電路提 供第二開啟電壓；該第二延時電路用於接收該輸入電流進 仃延時動作；該第二開關電路用於在該第二延時電路延時 動作完成後，接收該第二開啟電壓並打開，同時將該輸入 電流導向該電源輸出端以輸出。 200828800 如上所述’電流流經電源軟啟動裝置時，需要經過二 次延時才能輸出，若輸入電流的瞬間存在衝擊電流，該衝 擊電流會在該二次延時中消耗，而不會直接從電源輸出端 輸，，以保障後續電路的正常工作。斷電後第一開關電路 和第二開關電路因為沒有開啟電壓的輸入而關閉，為下一 次通電做好準備。 【實施方式】 如圖3所示，一較佳實施例的電源軟啟動裝置包括 電源輸入端1〇〇、分壓調節電路11〇、第一延時電路13〇、 第一開關電路150、第二延時電路17〇、第二開關電路19〇 和電源輸出端200。 電源輸入端1〇〇分別與分壓調節電路11〇、第一開關 電路150和第一開關電路19〇相連。第一延時電路與 ^壓調節電路110相連。第一開關電路15〇分別與分壓調 節電路110、第二延時電路170和第二開關電路19〇相連。 電源輸出端200與第二開關電路19〇相連。電源軟啟動裝 置1〇初始狀態時，第一開關電路150和第二開關電路19〇 均處於關閉狀態，也即斷開狀態，電流不能直接從電源輸 入端100流向電源輸出端2〇〇。 一法分壓調節電路11〇用於將來自電源輸入端1〇〇的輸入 ，抓導向第一延時電路13〇，並為第一開關電路15〇提供 第厂開啟電壓。第一延時電路13〇用於接收所述輸入電流 進2延時動作。第一開關電路15〇用於在第一延時電路13〇 延時動作完成後，接收所述第一開啟電壓並打開（導通）， 200828800 同時將輸入電流導向第二延時電路170並為第二開關電路 190提供第二開啟電壓。第二延時電路170用於接收所述 輸入電流進行延時動作。第二開關電路190用於在第二延 時電路170延時動作完成後，接收所述第二開啟電壓並打 開，同時將所述輸入電流導向電源輸出端200以輸出。輸 入電流斷電後，第一開關電路150和第二開關電路190由 於沒有開啟電壓的提供而關閉，為下一次的通電做好準備。 請參閱圖4，其為電源軟啟動裝置10的具體電路圖。 分壓調節電路110包括電性串聯的分壓電阻R10和可變電 阻W10，其中分壓電阻R10的一端與電源輸入端100相 連，另一端與可變電阻W10 —固定端相連；可變電阻W10 的另一固定端與第一延時電路130相連，可變電阻W10的 活動端與第一開關電路150相連。 第一延時電路130包括相互並聯的第一濾波電容 C10、穩壓管D10和第一電解電容C11。其中第一濾波電 容C10的一端、穩壓管D10的負極以及第一電解電容C11 的正極共同連接，並同時與可變電阻W10的一端相連；第 一濾波電容C10的另一端、穩壓管D10的正極以及第一電 解電容C11的負極共同接地。 第一開關電路150包括輸入電阻R11、上拉電阻R12 和NPN型三極管T10。其中輸入電阻R11的一端與可變電 阻W10的活動端相連，輸入電阻R11的另一端與三極管 T10的基極相連；上拉電阻R12的一端與電源輸入端100 相連，上拉電阻R12的另一端與三極管T10的集電極相 200828800 連，二極管T10的發射極分別與第二延時電路17〇和第二 —開關電路190相連。 ， 第二延時電路170包括相互並聯的第二濾波電容 C12、下拉電阻R13和第二電解電容C13。其中第二濾波 電容C12的一端、下拉電阻R13的一端以及第二電解電容 C13的正極共同相連，並同時與三極管T1〇的發射極相 連，第二濾波電容C12的另一端、下拉電阻R13的另一端 ^以及第二電解電容C13的負極共同接地。 第二開關電路190為一 m〇S管Ql〇。MOS管Qi〇的 漏極與電源輸入端1〇〇相連，MOS管Ql〇的柵極與三極管 T10的發射極相連’ MOS管Q10的源極與電源輪出端20Q 相連，為防止電流從MOS管Q10的漏極直接流入襯底（帶 箭頭的引腳），本實施例將MOS管Q10的襯底與源極相 連，也可以將襯底連接到最低電位上。 電流從電源輸入端100輸入後的短時間内，由於三極 ( 管T10和MOS管Q10都處於截止狀態，電流只能透過分 壓電阻R10和可變電阻W10對第一電解電容C11充電。 充電初始階段，由於分壓電阻R10以及部分可變電阻W10 的分壓，使A點的電壓不足以使三極管T10導通。隨著第 一電解電容C11的充電，第一電解電容C11兩端的電壓逐 漸升高’ A點的電壓也逐漸升高。當A點的電壓升高到三 極管T10的導通電壓時，三極管T10導通。 穩壓管D10用於保護第一電解電容C11，防止第一電 解電容C11兩端電壓過高導致擊穿損壞。當第一電解電容 11 200828800 C11兩端的電壓達到穩壓管D10的反向擊穿電壓時，穩壓 管D10反嚮導通，以避免第一電解電容C11兩端電壓的進 .一步增高。第一濾波電容C10用於濾除電流中的雜波。 三極管T10導通後，從電源輸入端100輸入的電流經 由上拉電阻R12對第二電解電容C13充電。三極管T10導 通後，B點的電壓隨著第二電解電容C13的充電逐漸增 加。當B點的電壓增加到MOS管Q10的開啟電壓時，MOS 管Q10開始導通，從電源輸入端100輸入的電流經由MOS " 管Q10流向電源輸出端200。基於MOS管Q10的開關特 性，在MOS管Q10的導通期間，MOS管Q10柵極的電壓 大小控制著流過漏極和源極的電流大小。MOS管Q10開始 導通後，隨著第二電解電容C13的繼續充電，B點的電壓 繼續增大，使得流過漏極和源極的電流也逐漸增大。 第二濾波電容C12用於濾除電流中的雜波。下拉電阻 R13用於在斷電後第一電解電容C11和第二電解電容C13 f 的放電，為下一次的電源輸出做好準備。電路斷電後，第 一電解電容C11透過可變電阻W10、輸入電阻R11和下拉 電阻13與地連接，進行放電；第二電解電容C13與下拉 電阻13形成回路，並進行放電。 請參閱圖5，其為電源軟啟動裝置10的輸入電流300 和輸出電流301的曲線示意圖’從圖中可以看出，輸入電 流300的開始階段有一個衝擊電流，輸出電流301比輸入 電流300出現的要晚，且輸入電流301為逐漸增加，最終 達到平穩狀態。請同時參閱圖6，其為電源軟啟動裝置10 12 200828800 的輸入電壓500和輸出電壓501的曲線示意圖，由於輸出 -電流3〇〇的開始階段存在一個衝擊電流，使得輸入電壓5〇〇 "開始較高，當衝擊電流過去後，輸出電流300再逐漸降低 到平穩狀態。輸出電壓501則與輸出電流300相對應，逐 漸升高到平穩狀態。 上述電源軟啟動裝置10,藉由第一電解電容C11和第 二電解電容C13的二階充電延時，並同時配合使用二個開 (關元件··三極管T10和MOS管Q10,使得輸入電流中^ 衝擊電流不會直接從電源輸出端200輸出，而在兩個延時 階&消耗，從而避免了衝擊電流對後續電路的損害。另外， 由於MOS管Q10的開關特性，通過其電流的大小隨著第 一電解電容C13充電的增加而增加，因此電源輸出端2〇〇 的輸出電流是逐漸增大，有效的保障後續電路的穩定工 作。電源軟啟動裝置10還可以藉由對可變電阻wl〇的調 節，控制第一電解電容C11的延時時間，以控制電源輸出 {端2〇〇的輸出。其中，本實施例的三極管T1〇和M〇s管 Q10僅為壓控開關元件的舉例，開關特性係藉由其一端的 電壓來控制其另外兩端的導通和截止，且三極管包括NpN 型和PNP型，MOS管包括N溝道型和p溝道型，其均能 貝現開關功能，只是對輸入電壓的要求不同。因此，本實 施例中的三極管T10和M0S管Q1〇可由其中的任意一種 代替’並對應調整相關電路。 【圖式簡單說明】 圖1為衝擊電流示意圖。 13 200828800 圖2為常用電源軟啟動電路原理圖。 圖3為一較佳實施例的電源軟啟動裝置原理框圖。 圖4為圖3所示的電源軟啟動裝置原理圖。 圖5圖3所示的電源軟啟動裝置之電流曲線示意圖 圖6圖3所示的電源軟啟動裝置之電壓曲線示意圖 【主要元件符號說明】 電源軟啟動裝置 10 分壓電阻 R10 可變電阻 W10 第一濾波電容 C10 穩壓管 D10 第一電解電容 C11 輸入電阻 R11 上拉電阻 R12 三極管 T10 第二濾波電容 C12 下拉電阻 R13 第二電解電容 C13 MOS 管 Q10 電源輸入端 100 、 分壓調節電路 110 第一延時電路 130 第一開關電路 150 第二延時電路 170 第二開關電路 190 電源輸出端 200 輸入電流 300 輸出電流 301 輸入電壓 500 輸出電壓 501 14200828800 IX. Description of the Invention: - Technical Field of the Invention - The present invention relates to a power supply device, and more particularly to a power soft start device. [Prior Art] Switching power supplies are widely used in communications, networking, industrial control, and consumer electronics, due to their small size, high performance, and ease of use. The switching power supply is used in the circuit to provide power for the operation of the circuit, which is the most basic requirement for the circuit operation. The input circuit of the switching power supply is usually in the form of bridge rectification plus capacitor filtering. At the moment when the input circuit is closed, since the initial voltage of the input filter capacitor is zero, the input filter capacitor is quickly charged, forming a large instantaneous surge current, also called surge current, which is much larger than the steady-state input current. As shown in Figure 1, the high-power switching power supply input uses a larger capacity filter capacitor, and its inrush current can reach 100A. At the moment when the switching power supply is turned on: So C. The large inrush current tends to cause damage to subsequent circuits, such as filter capacitors, causing the switching power supply to fail to operate normally. Therefore, a soft-start circuit that prevents inrush current is required in the switching power supply to ensure normal and reliable operation of the switching power supply. As shown in Figure 2, it is a conventional soft start circuit using a thermistor. The end of the thermistor R1 is connected to the positive output terminal of the rectifier D1, the other end of the thermistor R1 is connected to the positive terminal of the electrolytic capacitor C1, and the negative electrode of the electrolytic capacitor is connected to the negative output terminal of the rectifier 01. After the alternating current is rectified to direct current by the rectifier D1, the electrolytic capacitor is charged by the thermistor R1 at 200828800. The thermistor R1 has the characteristics of the temperature of the warehouse temperature 杳 in the winter, and its resistance value decreases rapidly with the increase of the temperature. Therefore, at the moment when the power is turned on, the resistance of the varistor R1 is large. It acts to limit the inrush current. As the amount of current flowing through the thermistor R1 gradually increases, the temperature of the thermistor Ri rises, the resistance value becomes smaller, and the circuit tends to operate normally. However, the use of thermistor R1 to prevent inrush current is generally applicable to small power switching power supplies. Due to the thermal inertia of the thermistor R1, it takes time to regain the high resistance state. Therefore, when the power supply needs to be turned on quickly after the power is turned off, the impact current is not limited. In addition, in actual operation, the thermistor is easily burned out and the entire circuit cannot work. SUMMARY OF THE INVENTION In view of the above, it is necessary to provide a stable power soft start device. A power soft start device includes a power input terminal, a voltage dividing adjusting circuit, a first delay circuit, a first switching circuit, a second delay circuit, a second switching circuit and a power output terminal, wherein the voltage dividing adjusting circuit is used to receive the power from the power source The input current of the input terminal is directed to the first delay circuit, and provides a first-on voltage for the first switch circuit; the first delay circuit is configured to receive the input current for delay operation; the first switch circuit is used for the first The delay circuit delay action is completed |, receiving the first turn-on voltage and turning on, and directing the input current to the second delay circuit and providing a second turn-on voltage for the second switch circuit; the second delay circuit is configured to receive the input The current switching delay action; the second switching circuit is configured to receive the second turn-on voltage and turn on after the delay operation of the second delay circuit is completed, and simultaneously direct the input current to the power output end for output. 200828800 As mentioned above, when the current flows through the soft start device of the power supply, it needs to be outputted after a second delay. If there is an inrush current at the moment of input current, the inrush current will be consumed in the second delay without being directly output from the power supply. End loss, to ensure the normal operation of the follow-up circuit. After the power is turned off, the first switch circuit and the second switch circuit are turned off because there is no input of the turn-on voltage, and are ready for the next power-on. [Embodiment] As shown in FIG. 3, a power soft start device according to a preferred embodiment includes a power input terminal 1〇〇, a voltage dividing adjustment circuit 11〇, a first delay circuit 13〇, a first switch circuit 150, and a second The delay circuit 17A, the second switch circuit 19A, and the power supply output terminal 200. The power input terminal 1 is connected to the voltage dividing adjustment circuit 11A, the first switching circuit 150, and the first switching circuit 19A, respectively. The first delay circuit is connected to the voltage regulation circuit 110. The first switching circuit 15A is connected to the voltage dividing adjustment circuit 110, the second delay circuit 170, and the second switching circuit 19A, respectively. The power output terminal 200 is connected to the second switching circuit 19A. When the power soft-start device is in the initial state, the first switch circuit 150 and the second switch circuit 19 are both in the off state, that is, the off state, and the current cannot flow directly from the power input terminal 100 to the power output terminal 2〇〇. A method of dividing the voltage regulating circuit 11 is for guiding the input from the power input terminal 1 to the first delay circuit 13A, and providing the first switching circuit 15? The first delay circuit 13 is configured to receive the input current into a delay action. The first switch circuit 15 is configured to receive the first turn-on voltage and turn on (on) after the delay operation of the first delay circuit 13 is completed, and the 200828800 simultaneously directs the input current to the second delay circuit 170 and is the second switch circuit. 190 provides a second turn-on voltage. The second delay circuit 170 is configured to receive the input current for a delay action. The second switch circuit 190 is configured to receive the second turn-on voltage and turn on after the delay operation of the second delay circuit 170 is completed, and simultaneously direct the input current to the power output terminal 200 for output. After the input current is de-energized, the first switching circuit 150 and the second switching circuit 190 are turned off due to the absence of the turn-on voltage supply, ready for the next energization. Please refer to FIG. 4 , which is a specific circuit diagram of the power soft start device 10 . The voltage dividing adjusting circuit 110 includes a voltage dividing resistor R10 and a variable resistor W10 electrically connected in series, wherein one end of the voltage dividing resistor R10 is connected to the power input terminal 100, and the other end is connected to the fixed end of the variable resistor W10; the variable resistor W10 The other fixed end is connected to the first delay circuit 130, and the active end of the variable resistor W10 is connected to the first switch circuit 150. The first delay circuit 130 includes a first filter capacitor C10, a Zener diode D10, and a first electrolytic capacitor C11 connected in parallel with each other. One end of the first filter capacitor C10, the cathode of the Zener diode D10, and the anode of the first electrolytic capacitor C11 are connected in common, and are simultaneously connected to one end of the variable resistor W10; the other end of the first filter capacitor C10, the Zener diode D10 The positive electrode and the negative electrode of the first electrolytic capacitor C11 are commonly grounded. The first switching circuit 150 includes an input resistor R11, a pull-up resistor R12, and an NPN type transistor T10. One end of the input resistor R11 is connected to the active end of the variable resistor W10, and the other end of the input resistor R11 is connected to the base of the transistor T10; one end of the pull-up resistor R12 is connected to the power input terminal 100, and the other end of the pull-up resistor R12 Connected to the collector phase 200828800 of the transistor T10, the emitter of the diode T10 is connected to the second delay circuit 17A and the second-switch circuit 190, respectively. The second delay circuit 170 includes a second filter capacitor C12, a pull-down resistor R13, and a second electrolytic capacitor C13 connected in parallel with each other. One end of the second filter capacitor C12, one end of the pull-down resistor R13, and the anode of the second electrolytic capacitor C13 are connected in common, and are simultaneously connected to the emitter of the transistor T1〇, the other end of the second filter capacitor C12, and the pull-down resistor R13 The one end ^ and the negative electrode of the second electrolytic capacitor C13 are commonly grounded. The second switching circuit 190 is a m〇S tube Q1〇. The drain of the MOS transistor Qi is connected to the power input terminal 1〇〇, and the gate of the MOS transistor Q1〇 is connected to the emitter of the transistor T10. The source of the MOS transistor Q10 is connected to the power supply terminal 20Q to prevent current from the MOS. The drain of the transistor Q10 flows directly into the substrate (the pin with an arrow). In this embodiment, the substrate of the MOS transistor Q10 is connected to the source, and the substrate can also be connected to the lowest potential. A short time after the current is input from the power input terminal 100, since the three poles (the tube T10 and the MOS tube Q10 are both turned off, the current can only charge the first electrolytic capacitor C11 through the voltage dividing resistor R10 and the variable resistor W10. In the initial stage, due to the voltage division of the voltage dividing resistor R10 and the partial variable resistor W10, the voltage at point A is insufficient to turn on the transistor T10. As the first electrolytic capacitor C11 is charged, the voltage across the first electrolytic capacitor C11 gradually rises. The voltage at the high 'A point is also gradually increased. When the voltage at point A rises to the turn-on voltage of the transistor T10, the transistor T10 is turned on. The Zener diode D10 is used to protect the first electrolytic capacitor C11 and prevent the first electrolytic capacitor C11 from being If the voltage across the first electrolytic capacitor 11 200828800 C11 reaches the reverse breakdown voltage of the Zener diode D10, the Zener diode D10 reverses to avoid the first electrolytic capacitor C11. The voltage is increased by one step. The first filter capacitor C10 is used to filter out the clutter in the current. After the transistor T10 is turned on, the current input from the power input terminal 100 is passed through the pull-up resistor R12 to the second electrolytic capacitor C13. Charging. After the transistor T10 is turned on, the voltage at point B gradually increases with the charging of the second electrolytic capacitor C13. When the voltage at point B increases to the turn-on voltage of the MOS transistor Q10, the MOS transistor Q10 starts to conduct, and is input from the power input terminal 100. The current flows through the MOS " tube Q10 to the power supply output terminal 200. Based on the switching characteristics of the MOS transistor Q10, during the conduction period of the MOS transistor Q10, the voltage of the gate of the MOS transistor Q10 controls the current flowing through the drain and the source. After the MOS transistor Q10 starts to conduct, as the second electrolytic capacitor C13 continues to charge, the voltage at point B continues to increase, so that the current flowing through the drain and the source also gradually increases. The second filter capacitor C12 is used for filtering. In addition to the clutter in the current, the pull-down resistor R13 is used to discharge the first electrolytic capacitor C11 and the second electrolytic capacitor C13f after the power is turned off, and is ready for the next power output. After the circuit is powered off, the first electrolytic capacitor C11 is connected to the ground through the variable resistor W10, the input resistor R11 and the pull-down resistor 13 to discharge, and the second electrolytic capacitor C13 and the pull-down resistor 13 form a loop and discharge. Referring to FIG. 5, the power soft start device 10 is shown. A schematic diagram of the input current 300 and the output current 301. As can be seen from the figure, there is an inrush current at the beginning of the input current 300, the output current 301 is later than the input current 300, and the input current 301 is gradually increased. Finally, it reaches a steady state. Please also refer to Figure 6, which is a schematic diagram of the input voltage 500 and the output voltage 501 of the power soft-start device 10 12 200828800. Since there is an inrush current at the beginning of the output-current 3〇〇, the input voltage is made. 5〇〇" starts higher, and when the inrush current passes, the output current 300 gradually decreases to a steady state. The output voltage 501 corresponds to the output current 300 and gradually rises to a steady state. The power soft-start device 10 has a second-order charging delay of the first electrolytic capacitor C11 and the second electrolytic capacitor C13, and simultaneously uses two open (closed components, the transistor T10 and the MOS transistor Q10, so that the input current is impacted) The current is not directly output from the power supply output terminal 200, but is consumed in two delay stages & thereby avoiding damage to the subsequent circuit by the rush current. In addition, due to the switching characteristics of the MOS transistor Q10, the magnitude of the current through the MOS tube Q10 The increase of the charging of an electrolytic capacitor C13 increases, so that the output current of the output terminal of the power supply is gradually increased, which effectively ensures the stable operation of the subsequent circuit. The power soft start device 10 can also be used by the variable resistor w1〇. Adjusting and controlling the delay time of the first electrolytic capacitor C11 to control the output of the power output {terminal 2〇〇. Among them, the triode T1〇 and the M〇s tube Q10 of the embodiment are only examples of the voltage-controlled switching element, and the switching characteristics The other ends are controlled by the voltage at one end thereof, and the transistors include NpN type and PNP type, and the MOS tube includes an N-channel type and a p-channel type, and both of them can be present. The function is only different for the input voltage. Therefore, the triode T10 and the MOS tube Q1〇 in this embodiment can be replaced by any one of them and correspondingly adjust the related circuit. [Simplified Schematic] FIG. 1 is a schematic diagram of the inrush current Fig. 2 is a schematic diagram of a common power soft start circuit. Fig. 3 is a block diagram of a power soft start device according to a preferred embodiment. Fig. 4 is a schematic diagram of the power soft start device shown in Fig. 3. Fig. 5Fig. Schematic diagram of the current curve of the power soft-start device shown in Figure 6 Figure 3 shows the voltage curve of the power soft-start device [Main component symbol description] Power soft-start device 10 Voltage divider resistor R10 Variable resistor W10 First filter capacitor C10 Zener diode D10 first electrolytic capacitor C11 input resistor R11 pull-up resistor R12 transistor T10 second filter capacitor C12 pull-down resistor R13 second electrolytic capacitor C13 MOS transistor Q10 power input terminal 100, voltage divider circuit 110 first delay circuit 130 a switching circuit 150 second delay circuit 170 second switching circuit 190 power output terminal 200 input current 300 output current 3 01 Input voltage 500 Output voltage 501 14