201123683 六、發明說明： 【發明所屬之技術領域】 ⑽01] 本發明涉及一種電子電路，特別涉及一種能夠自動切換 供電電源的電源切換電路。 【先前技術】 [0002] 目前，一般的電子裝置如手機、MP3播放器、電子相框等 電子設備大多有多種供電方式，比如電池供電或通過USB 介面、市電適配器等外部電源供電等方式。 [0003] —般，為了提高電池的使用壽命，減少電池充放電次數 ，在有外部電源時，一般選擇外部電源供電。現有的電 源選擇通常為在電池、外部電源與公共輸出端之間加各 加一二極體，根據電麼的高低自動選擇供電的電源，由 於手機等電池電壓通常為3. 7V，USB介面的電壓通常為 5V，市電適配器的電源通常為12V，從而可選擇USB介面 以及市電適配器等外部電源供電。 [0004] 然而，在電池電壓高於外部電源時，則會選擇電池供電 ，從而無法達到預期的採用外部電源供電減少電池充放 電次數的效果。 【發明内容】 [0005] 有鑒於此，提供一種通過簡單的電源切換電路及可自動 切換供電電源的電子裝置，實現在外部電源電壓低於電 池電壓時，也可自動選擇外部電源為該電子裝置供電。 [0006] 一種電源切換電路，包括外部電源介面、電池座、選擇 開關、第一單嚮導通開關以及第二單嚮導通端。該外部 098144079 表單編號A0101 第4頁/共15頁 0982075425-0 201123683 電源介面以及電池座分別供外部電源以及電池接入。選 • 擇開關包括一控制端與該外部電源介面連接，一第一導 通端與該電池座連接。第一單嚮導通開關，位於該選擇 開關的第二導通端與一電壓輸出端之間，單嚮導通從電 池到該電壓輸出端的電流。第二單嚮導通端，位於外部 電源介面與該電壓輸出端之間，單嚮導通從外部電源到 該電壓輸出端的電流。當該外部電源介面接入外部電源 時，該選擇開關的控制端獲得一高電平，從而使得該選 擇開關截止，電池與該電壓輸出端之間的電流路徑被切 Ο 斷，從而該外部電源輸出電壓至該電壓輸入端為後續電 路供電。 [0007] —種可自動切換供電電源的電子裝置，包括耗電元件以 及電源切換電路，該電源切換電路包括外部電源介面及 電池座、選擇開關、第一單嚮導通開關以及第二單嚮導 通開關。該外部電源介面及電池座分別供外部電源以及 電池接入。選擇開關包括一控制端與該外部電源介面連 ^ 接，一第一導通端與該電池座連接。第一單嚮導通開關 〇 ，位於該選擇開關的第二導通端與一電壓輸出端之間， 單嚮導通從電池到該電壓輸出端的電流。第二單嚮導通 端，位於外部電源介面與該電壓輸出端之間，單嚮導通 從外部電源到該電壓輸出端的電流。當該外部電源介面 接入外部電源時，該選擇開關的控制端獲得一高電平， 從而使得該選擇開關截止，電池與該.電壓輸出端之間的 電流路徑被切斷，從而該外部電源輸出電壓至該電壓輸 入端為電子裝置的耗電元件供電。 098144079 表單編號A0101 第5頁/共15頁 0982075425-0 201123683 刚通過本發明的電源一電路及應心㈣路的電子裝置， 當有外部電源接人時’不論外部⑼、電麼是否低於電池 電壓，均選擇外部_«電子襄置供電，提高電池使 用舞命。 【實施方式】 _] ϋ參閱圖卜為電池切換電路第〜實施方式的電路架構圖 。電池切換電路1 〇包括一電池座1 〇 1以及一外部電源介面 102分別接入電池20以及外部電源30，該電池切換電路 10用於切換選擇電池2〇供電或外部電源3〇供電。該電池 切換電路10可置於手機、音樂播放器、個人數位助理（ PDA’ Personal Digital Assistant)以及電子相框 ^ Λ . 等電子裝置（圖中未示）中，用於切换選擇為該電子裝 置中的耗電元件（圖中未示）供電的電禅。 [0010] 該電池切換電路10還包括選擇開關103，選擇開關103包 括控制端1031、第一導通端1〇32以及第二導通端1〇33。 控制端1031與外部電源介面1〇2連接，第一導通端1〇32 與電池座101連接〇痛本實施方式中，該選擇開關1〇3為 一低電平導通開關，即當選擇開關1〇3的控制端1031位於 低電平時’該選擇開關1〇3導通，當選擇開關103的控制 端1031位於南電平時，該選擇開關^03截止。 [0011] 該電池切換電路10還包括第一單嚮導通開關104以及第二 單嚮導通開關105 ’第—單嚮導通開關1〇4位於該選擇開 關103的第二導通端1 033與一電壓輸出端40之間，該第 二單嚮導通開關105位於外部電游30與該電壓輸出端40之 098144079 間。 表單編號A0101 第6頁/共15頁 0982075425-0 201123683 [0012] [0013]Ο [0014] 〇 [0015] 當該電池切換電路10僅通過電池座101連接電池20時，電 池20作為電源通過電壓輸出端40為後續的耗電元件（圖 中未示）供電。當該電池切換電路10通過外部電源介面 102連接外部電源30時，該選擇開關103的控制端1031通 過外部電源介面102從外部電源30獲得一高電平，從而該 選擇開關103相應截止，電池20至電壓輸出端40之間的路 徑被切斷。從而，該電池切換電路10僅選擇外部電源30 供電。 從而可以儘量採用外部電源30供電，延長設備的供電時 間，並減少電池的使用及充放電時間，提高電池使用壽 命。 請參閱圖2所示，為電源切換電路第一實施方式的具體電 路圖。其中，在該具體電路中，外部電源介面102以USB 介面102為例，外部電源30相應以USB介面電源為例進行 說明，在其他實施方式中，該外部電源介面102可以為市 電適配器介面、IEEE1 394介面等。此外，具體電路中該 第一、第二單嚮導通開關104、105分別為二極體Dl、D2 ，且二極體D1的陽極通過選擇開關103後與電池座101的 電壓正極端相連，二極體D2的陽極與USB介面102的電壓 正極端相連。 在該具體電路中，該選擇開關103為一PMOS管Q1，其中 PMOS管Q1的柵極、源極以及漏極分別對應該選擇開關 103的控制端1031、第一導通端1032以及第二導通端 1033。 098144079 表單編號A0101 第7頁/共15頁 0982075425-0 201123683 [_ PM0S管_柵極與USB介面1〇2的電麗正極端連接源極 。电池座101❾電壓正極端連接，漏極與該二極體Μ的陽 極連接。 _]當該USB介面102未接入USB介面電源而僅電池座1〇1接入 電池20時，PM0S管Q1導通，電池2〇通過該導通的管 Q1以及該二極體D1輸出電壓至電壓輪出端4〇，從而為電 子裝置供電。 [0018] 當USB介面102接入USB介面電源後，PM0S管〇1的柵極通 過該USB介面102獲得一高電平，從而使得該pM〇s管以截 止，電池20與電壓輸出端40的電流路徑被切斷。此時， USB介面電源的電壓通過該二極體D2輪出至電壓輸出端4〇 為電子裝置供電。 [0019] 在該具體電路中，USB介面電源的輸出電壓為5V，電池2〇 的輸出電壓可以為3V-8V，我們選用的PM0S管Q1的門限 電壓Vth為3V ’由於只要PM0S管Q1的源植輿柵極的電勢差 小於3V ’則該PM0S鐵:Q1即處'於截..止狀鱔，因此，只要該 USB介面102接入了 USB電源，該PM0S管Q1的源極與栅極 的電勢差即會小於3V，從而截止該PM0S管Q1。可以理解 的，根據電池20的電壓不同，可以選用具有相應門限電 壓的PM0S管Q1。 [0020] 在其他實施方式中，該選擇開關103為PNP三極管，PNP 三極管的基極、發射極、集電極分別對應該選擇開關1 〇3 的控制端1031、第一導通端1032、第二導通端1 033。 [0021] 在圖2所示的具體電路中，還包括電阻R1以及R2，電阻R1 098144079 表單編號A0101 第8頁/共15頁 201123683 R2為負載電阻，作為私山々 •點無關，故不在此多加贅述載匹配’由於與本發明要 [0022] ^而本發明通過—簡單的電源切換電路，即使在外部 電源的電壓低於電池電壓 a /、要接入垓外部電源則自 動選擇外部電源供電 —電k而減少電池的使用，減少電池 的充放電次數，提高電池壽命。 [0023] 【圖式簡單說明】 圖1為電池切換電路第一實施方式的電路架構圖 〇 [0024] 圖2為電池切換電路第一實施方式的具體電路圖 【主要元件符號說明】 • [0025] 電池切換電路：10 [0026] 電池：20 [0027] 外部電源：30 [0028] 電麼輸出端：40 9 ' γ [0029] 〇 _ , ^ ' r , , :*γ·' 電池座：101 ^ % 5? si ：·； ί ；：ί·4·| [0030] 外部電源介面：102 [0031] 選擇開關：103 [0032] 第一單嚮導通開關：104 [0033] 第一早嚮導通開關：105 [0034] 控制端：1031 [0035] 第一導通端：1032 098144079 表單編號A0101 第9頁/共15頁 0982075425-0 201123683 [0036] 第二導通端：1033 [0037] PMOS 管：Q1 [0038] USB介面：102 [0039] 二極體：D1/D2 [0040] 電阻：R1/R2201123683 VI. Description of the Invention: [Technical Field of the Invention] (10) 01 The present invention relates to an electronic circuit, and more particularly to a power supply switching circuit capable of automatically switching a power supply. [Prior Art] [0002] At present, most electronic devices such as mobile phones, MP3 players, and electronic photo frames have various power supply modes, such as battery power supply or external power supply through a USB interface or a power adapter. [0003] Generally, in order to improve the service life of the battery and reduce the number of times of charging and discharging the battery, when an external power source is provided, the external power supply is generally selected. The current power supply selection is usually to add a diode between the battery, the external power supply and the common output, and the power supply is automatically selected according to the height of the power, because the battery voltage of the mobile phone is usually 3. 7V, the USB interface The voltage is usually 5V, and the mains adapter's power supply is usually 12V, so you can choose the USB interface and external power supply such as the mains adapter. [0004] However, when the battery voltage is higher than the external power supply, the battery power is selected, so that the expected use of the external power supply reduces the number of times the battery is charged and discharged. SUMMARY OF THE INVENTION [0005] In view of this, a simple power supply switching circuit and an electronic device capable of automatically switching a power supply are provided, so that when the external power supply voltage is lower than the battery voltage, the external power supply can be automatically selected as the electronic device. powered by. [0006] A power switching circuit includes an external power supply interface, a battery holder, a selection switch, a first one-way switch, and a second one-way terminal. The external 098144079 Form No. A0101 Page 4 of 15 0982075425-0 201123683 The power interface and battery holder are for external power supply and battery access. The selection switch includes a control terminal connected to the external power supply interface, and a first conductive terminal connected to the battery holder. The first one-way switch is located between the second conduction end of the selection switch and a voltage output terminal, and directs the current from the battery to the voltage output terminal. The second single-conductor terminal is located between the external power supply interface and the voltage output terminal, and directs the current from the external power supply to the voltage output terminal. When the external power interface is connected to the external power source, the control terminal of the selection switch obtains a high level, so that the selection switch is turned off, and the current path between the battery and the voltage output terminal is cut off, thereby the external power source The output voltage is supplied to the voltage input terminal for subsequent circuits. [0007] An electronic device capable of automatically switching a power supply, comprising a power consuming component and a power switching circuit, the power switching circuit comprising an external power supply interface and a battery holder, a selection switch, a first one-way switch, and a second one-way communication switch. The external power supply interface and the battery holder are respectively connected to an external power source and a battery. The selection switch includes a control terminal connected to the external power supply interface, and a first conductive terminal is connected to the battery holder. The first one-way switch 〇 is located between the second conduction end of the selection switch and a voltage output terminal, and directly conducts current from the battery to the voltage output terminal. The second one-way terminal is located between the external power supply interface and the voltage output terminal, and directs current from the external power supply to the voltage output terminal. When the external power interface is connected to the external power source, the control terminal of the selection switch obtains a high level, so that the selection switch is turned off, and the current path between the battery and the voltage output terminal is cut off, thereby the external power source The output voltage to the voltage input provides power to the power consuming components of the electronic device. 098144079 Form No. A0101 Page 5 of 15 0982075425-0 201123683 Just passed the power supply circuit of the present invention and the electronic device of the heart (four) road, when there is an external power supply, 'whether external (9), electricity is lower than the battery The voltage is selected from the external _« electronic power supply to improve the battery life. [Embodiment] _] 图 Refer to FIG. 2B is a circuit diagram of the battery switching circuit. The battery switching circuit 1 includes a battery holder 1 〇 1 and an external power supply interface 102 for respectively connecting the battery 20 and the external power source 30 for switching the selection of the battery 2 or the external power supply. The battery switching circuit 10 can be placed in an electronic device (not shown) such as a mobile phone, a music player, a personal digital assistant (PDA' Personal Digital Assistant), and an electronic photo frame, for switching to select the electronic device. The electric zen of the power consuming component (not shown) is powered. [0010] The battery switching circuit 10 further includes a selection switch 103 including a control terminal 1031, a first conduction terminal 1〇32, and a second conduction terminal 1〇33. The control terminal 1031 is connected to the external power supply interface 1〇2, and the first conductive terminal 1〇32 is connected to the battery holder 101. In the embodiment, the selection switch 1〇3 is a low-level conduction switch, that is, when the selection switch 1 is selected. When the control terminal 1031 of the 〇3 is at a low level, the selection switch 1〇3 is turned on, and when the control terminal 1031 of the selection switch 103 is at the south level, the selection switch ^03 is turned off. [0011] The battery switching circuit 10 further includes a first one-way switch 104 and a second one-way switch 105 'the first one-way switch 1 〇 4 is located at the second conduction end 1 033 of the selection switch 103 and a voltage Between the output terminals 40, the second one-way switch 105 is located between the external power play 30 and the 098144079 of the voltage output terminal 40. Form No. A0101 Page 6 / Page 15 0982075425-0 201123683 [0013] [0015] When the battery switching circuit 10 connects the battery 20 only through the battery holder 101, the battery 20 acts as a power supply voltage. The output terminal 40 supplies power to subsequent power consuming components (not shown). When the battery switching circuit 10 is connected to the external power source 30 through the external power source interface 102, the control terminal 1031 of the selection switch 103 obtains a high level from the external power source 30 through the external power source interface 102, so that the selection switch 103 is turned off correspondingly, and the battery 20 is turned off. The path to the voltage output 40 is cut off. Thus, the battery switching circuit 10 selects only the external power source 30 to supply power. Therefore, the external power source 30 can be used as much as possible to extend the power supply time of the device, reduce the battery usage, charge and discharge time, and improve the battery life. Please refer to FIG. 2, which is a specific circuit diagram of the first embodiment of the power switching circuit. In the specific circuit, the external power interface 102 is exemplified by the USB interface 102, and the external power supply 30 is illustrated by using a USB interface power supply. In other embodiments, the external power interface 102 can be a commercial power adapter interface, IEEE1. 394 interface and so on. In addition, in the specific circuit, the first and second one-way switches 104 and 105 are diodes D1 and D2, respectively, and the anode of the diode D1 is connected to the positive terminal of the voltage of the battery holder 101 through the selection switch 103. The anode of the body D2 is connected to the positive terminal of the voltage of the USB interface 102. In the specific circuit, the selection switch 103 is a PMOS transistor Q1, wherein the gate, the source and the drain of the PMOS transistor Q1 respectively correspond to the control terminal 1031, the first conduction terminal 1032 and the second conduction terminal of the selection switch 103. 1033. 098144079 Form No. A0101 Page 7 of 15 0982075425-0 201123683 [_ PM0S tube_gate and USB interface 1〇2 The positive terminal of the battery is connected to the source. The battery holder 101 is connected to the positive terminal of the voltage, and the drain is connected to the anode of the diode. _] When the USB interface 102 is not connected to the USB interface power supply and only the battery holder 1〇1 is connected to the battery 20, the PM0S tube Q1 is turned on, and the battery 2〇 outputs a voltage to the voltage through the turned-on tube Q1 and the diode D1. The wheel end 4 〇 to power the electronic device. [0018] When the USB interface 102 is connected to the USB interface power supply, the gate of the PM0S transistor 1 obtains a high level through the USB interface 102, so that the pM〇s tube is turned off, and the battery 20 and the voltage output terminal 40 are The current path is cut. At this time, the voltage of the USB interface power supply is turned to the voltage output terminal 4 through the diode D2 to supply power to the electronic device. [0019] In the specific circuit, the output voltage of the USB interface power supply is 5V, the output voltage of the battery 2〇 can be 3V-8V, and the threshold voltage Vth of the PM0S tube Q1 that we select is 3V 'as long as the source of the PM0S tube Q1 The potential difference of the tantalum gate is less than 3V 'The PM0S iron: Q1 is 'in the cut.. Stop, so as long as the USB interface 102 is connected to the USB power supply, the source and the gate of the PM0 transistor Q1 The potential difference is less than 3V, thereby turning off the PM0S tube Q1. It can be understood that, depending on the voltage of the battery 20, the PM0S tube Q1 having the corresponding threshold voltage can be selected. [0020] In other embodiments, the selection switch 103 is a PNP transistor, and the base, the emitter, and the collector of the PNP transistor respectively correspond to the control terminal 1031, the first conduction terminal 1032, and the second conduction of the switch 1 〇3. End 1 033. [0021] In the specific circuit shown in FIG. 2, the resistors R1 and R2 are further included, the resistor R1 098144079, the form number A0101, the eighth page, the total of 15 pages, the 201123683 R2 is the load resistor, as a private mountain, the point is irrelevant, so it is not added here. The description of the load matching 'because of the invention [0022] ^ and the invention through a simple power switching circuit, even if the external power supply voltage is lower than the battery voltage a /, to access the external power supply automatically selects the external power supply - The electric k reduces the use of the battery, reduces the number of times the battery is charged and discharged, and improves the battery life. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a first embodiment of a battery switching circuit. [0024] FIG. 2 is a specific circuit diagram of a first embodiment of a battery switching circuit. [Description of Main Components] [0025] Battery switching circuit: 10 [0026] Battery: 20 [0027] External power supply: 30 [0028] Electrical output: 40 9 ' γ [0029] 〇 _ , ^ ' r , , : * γ · ' Battery holder: 101 ^ % 5? si :·; ί ;: ί·4·| [0030] External power supply interface: 102 [0031] Selector switch: 103 [0032] First one-way switch: 104 [0033] First early pass Switch: 105 [0034] Control terminal: 1031 [0035] First conduction end: 1032 098144079 Form number A0101 Page 9 / Total 15 page 0982075425-0 201123683 [0036] Second conduction end: 1033 [0037] PMOS tube: Q1 [0038] USB interface: 102 [0039] Diode: D1/D2 [0040] Resistor: R1/R2
098144079 表單編號A0101 第10頁/共15頁 0982075425-0098144079 Form No. A0101 Page 10 of 15 0982075425-0