M323156 述採用蕭特基二極體作為保護電路仍有一缺點，亦 疋蕭特基一極體之順向電壓（f〇rward v〇itage)為 0.45V’所以當此車用充電器進行充電的時，耗電流 為1A，而會在蕭特基二極體浪費〇·45瓦特。此外， 此電源保護電路僅能保護電子裝置13不致燒毁，但 無法提示使用者電源誤接。 【新型内容】 因此本創作的目的在於提供一種電源保護電 路，以達到兼顧電源誤接提示及減少不必要功耗的 功效。 根據本創作之上述目的，本創作亦提供一種電 源保護電路，此電源保護電路設置在一電源供應裝 置及一電子裝置之間，其中電源供應裝置係輸出一 電壓’此電源保護電路至少包含一警示電路及一切 換電路。此警示電路係耦接電源供應裝置以接收電 壓並彳貞測此電壓是否高於一第一臨界電壓，以決定 疋否發出一警訊信息。而切換電路係耦接電源供應 裝置及電子裝置，並依據電壓是否高於一第二臨界 電壓’以決定是否導通電壓至電子裝置。 其中’切換電路係包含複數個電晶體，藉此以 降低電路導通時所消耗的功耗。 6 M323156 333係為一接地端。此電源保護電路30包含一警示 電路31及一切換電路32，警示電路31之基本元件 至少包含串接的發光二極體311及二極體312。且 發光二極體311之陰極端（cathode)連接至電源供 應裝置33之一輸出端，而及發光二極體311之陽極 ， 端（anode)係連接至二極體312之一陰極端而其陽 . 極端係連接電源供應裝置33之接地端333。 而切換電路32之基本元件至少包含一第一電 > 晶體321、一第二電晶體322及一電阻323。在此實 施例中，第一電晶體321係為一 P-型金氧半導體電 晶體（PM0S)，第二電晶體322係為一 NPN型雙載子 接面電晶體（bipolar junction transistor，BJT)。 電阻323係連接第一電晶體321之源極端（source) 及閘極端（gate)。第一電晶體321之閘極端係連接 第二電晶體322之集極端（collect)，而其汲極端 (drain)係與電子裝置22之正輸入端221連接。第 ，二電晶體322之之基極端（base)連接一參考正電 壓，而第二電晶體322之射極端（emit)係連接電源 供應裝置33之接地端333。電子裝置22之負輸入 端222亦連接電源供應裝置33之接地端333。 當使用者將電源供應裝置之輸出端332誤接於 電源保護電路30時，輸出端332輸出之負電壓導致 發光二極體411及二極體412進入一順向偏壓（bias) 狀態，而發光二極體411可發光以警示使用者電源 8 M323156 誤接之現象。在此，由於發光二極體額定的反向擊 ^電壓值一般比較低，往往10〜20伏特的反向電壓 就了犯k成毛光一極體損壞。因此，在本實施例中， 額外與發光二極體411串接二極體412，以提高警 不電路31之反向電壓，達到保護發光二極體411 的功效。 同時，第二電晶體322之集極端及基極端接收 到負電壓，而射極端4223為接地端，亦造成vBE小 於零，使得第二電晶體322呈不導通的狀態。且此 負電壓亦造成第一電晶體321之閘極和源極（G代表 閘極，S代表源極）間的電壓Va為負電壓值，小於一M323156 There is still a disadvantage in using the Schottky diode as a protection circuit. The forward voltage (f〇rward v〇itage) of the Schottky diode is 0.45V, so when the car is charged with a charger. At that time, the current consumption is 1A, and it will waste 〇45 watts in the Schottky diode. In addition, the power protection circuit can only protect the electronic device 13 from burning, but cannot prompt the user to misconnect the power. [New content] Therefore, the purpose of this creation is to provide a power protection circuit to achieve the power supply misconnection prompt and reduce unnecessary power consumption. According to the above object of the present invention, the present invention also provides a power protection circuit disposed between a power supply device and an electronic device, wherein the power supply device outputs a voltage 'this power protection circuit includes at least one warning Circuit and a switching circuit. The warning circuit is coupled to the power supply device to receive the voltage and to determine whether the voltage is higher than a first threshold voltage to determine whether a warning message is issued. The switching circuit is coupled to the power supply device and the electronic device, and determines whether to turn on the voltage to the electronic device according to whether the voltage is higher than a second threshold voltage. The 'switching circuit' includes a plurality of transistors to reduce the power consumption when the circuit is turned on. 6 M323156 333 is a ground terminal. The power protection circuit 30 includes a warning circuit 31 and a switching circuit 32. The basic components of the warning circuit 31 include at least the LEDs 311 and the diodes 312 connected in series. And a cathode terminal of the light emitting diode 311 is connected to one of the output ends of the power supply device 33, and an anode of the light emitting diode 311 is connected to one of the cathode ends of the diode 312. The terminal is connected to the grounding end 333 of the power supply unit 33. The basic component of the switching circuit 32 includes at least a first electrical circuit 321 , a second transistor 322 , and a resistor 323 . In this embodiment, the first transistor 321 is a P-type MOS transistor (PM0S), and the second transistor 322 is an NPN-type bipolar junction transistor (BJT). . The resistor 323 is connected to the source and gate of the first transistor 321 . The gate terminal of the first transistor 321 is connected to the collector of the second transistor 322, and its drain is connected to the positive input terminal 221 of the electronic device 22. The base of the second transistor 322 is connected to a reference positive voltage, and the emitter of the second transistor 322 is connected to the ground terminal 333 of the power supply unit 33. The negative input terminal 222 of the electronic device 22 is also coupled to the ground terminal 333 of the power supply unit 33. When the user mistakenly connects the output terminal 332 of the power supply device to the power protection circuit 30, the negative voltage outputted from the output terminal 332 causes the LED 411 and the diode 412 to enter a forward bias state. The LED 411 can emit light to warn the user that the power supply 8 M323156 is misconnected. Here, since the rated reverse voltage of the light-emitting diode is generally low, a reverse voltage of 10 to 20 volts is often caused by damage to the hair. Therefore, in the present embodiment, the diode 412 is additionally connected in series with the LED 411 to increase the reverse voltage of the alarm circuit 31, thereby achieving the effect of protecting the LED 411. At the same time, the collector terminal and the base terminal of the second transistor 322 receive a negative voltage, and the emitter terminal 4223 is grounded, which also causes vBE to be less than zero, so that the second transistor 322 is in a non-conducting state. And the negative voltage also causes the voltage Va between the gate and the source of the first transistor 321 (G represents the gate, and S represents the source) to be a negative voltage value, less than one.
臨界電壓值（threshold voltage，Vth，取 Vth為 1 V 至3V範圍之間），所以，此p-型的m〇SFET 421是 處在「截止」（cut-off)的狀態，電流無法流過p一 型的M0SFET 421，也就是P-型的M0SFET 421不導 通。因此，當使用者誤接電源，則電源保護電路30 可發光警示使用者且保護電子裝置不因負電壓而燒 毁0 當使用者將電源供應裝置之輸出端331連接於 電源保護電路30時，輸出端332輸出之負電壓導致 發光二極體311及二極體312進入一逆向偏壓狀 態，所以，第一串聯電路之發光二極體311與二極 體312皆不導通，亦是此發光二極體311不會有產 生發光現象。 M323156 圖； 第2圖繪示本創作之電源保護電路之方塊圖； 以及 第3圖繪示本創作之電源保護電路之實施電路 之示意圖。The threshold voltage (Vth, Vth is between 1 V and 3 V), so the p-type m〇SFET 421 is in a "cut-off" state, and the current cannot flow. The p-type MOSFET 421, that is, the P-type MOSFET 421, is not turned on. Therefore, when the user mistakenly connects the power source, the power protection circuit 30 can illuminate the user and protect the electronic device from being burnt due to the negative voltage. When the user connects the output terminal 331 of the power supply device to the power protection circuit 30, The negative voltage outputted by the output terminal 332 causes the LED 311 and the diode 312 to enter a reverse bias state. Therefore, the LED 311 and the diode 312 of the first series circuit are not conductive, and the illumination is also The diode 311 does not cause luminescence. M323156; FIG. 2 is a block diagram of the power protection circuit of the present invention; and FIG. 3 is a schematic diagram showing the implementation circuit of the power protection circuit of the present invention.
【主要元件符號說明】 11: 車用充電器； 12: 蕭特基二極體； 13: 電子裝置； 21: 電源供應裝置； 211： 電壓； 22: 電子裝置； 221： 正輸入端； 222: 負輸入端； 23: 電源保護裝置； 231:警示電路； 2 3 2:切換電路； 30:電源保護電路； 31:警示電路； 311:第一二極體； 312:發光二極體； 32:切換電路； 11 M323156 321:第一電晶體； 322:第二電晶體； 323:電阻； 33:電源供應裝置；以及 331,332, 333:輸出端。[Main component symbol description] 11: car charger; 12: Schottky diode; 13: electronic device; 21: power supply device; 211: voltage; 22: electronic device; 221: positive input terminal; Negative input; 23: power protection device; 231: warning circuit; 2 3 2: switching circuit; 30: power protection circuit; 31: warning circuit; 311: first diode; 312: light-emitting diode; Switching circuit; 11 M323156 321: first transistor; 322: second transistor; 323: resistor; 33: power supply; and 331, 332, 333: output.
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