Charging and discharging circuit

Abstract

A charging and discharging circuit includes a charging and discharging control circuit, a first connection port, a first switching circuit, a second switching circuit, a second connection port, a third switching circuit, a fourth switching circuit, and an identification logic circuit. The identification logic circuit determines the mode of the first connection port based on a first channel configuration signal. The charging and discharging control circuit switches the first and second switching circuits based on the mode of the first connection port, and determines the mode of the second connection port based on a second channel configuration signal to switch the third and fourth switching circuits.

Description

Technical Field

[0001] This invention relates to a charging and discharging circuit, and more particularly to a charging and discharging circuit that enables dual USB ports to be used independently and charged and discharged in a mobile electronic device. Background Technology

[0002] In existing charging and discharging circuits, if two or more USB ports simultaneously power the system of a mobile electronic device, the voltage difference between these USB ports will cause power leakage, thus damaging some of the adapters in these USB ports.

[0003] On the other hand, if one of the USB ports is to charge the system of a mobile electronic device, and the system outputs via another USB port using the USB On-The-Go (OTG) standard, the USB port that is inserted later will not function properly. For example, if the USB port used for charging is inserted later, it will not be able to charge, and if the USB port used for OTG output is inserted later, it will not be able to output via OTG. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a charging and discharging circuit that enables dual USB ports to be used independently and charged and discharged in a mobile electronic device, overcoming the shortcomings of the prior art.

[0005] To address the aforementioned technical problems, one technical solution adopted by this invention is to provide a charging and discharging circuit that connects a battery module to a system-level circuit. The charging and discharging circuit includes a charging and discharging control circuit, a first connection port, a first switch circuit, a second switch circuit, a second connection port, a third switch circuit, a fourth switch circuit, and an identification logic circuit. The charging and discharging control circuit has a first input terminal, a second input terminal, an identification terminal, a battery terminal, and an output terminal, wherein the battery terminal is connected to the battery module, and the output terminal is connected to the system-level circuit. The first switch circuit is connected between the first connection port and the first input terminal to form a first charging path. The second switch circuit is connected between the first connection port and the output terminal to form a first discharging path. The third switch circuit is connected between the second connection port and the second input terminal to form a second charging path. The fourth switch circuit is connected between the second connection port and the output terminal to form a second discharging path. An identification logic circuit is connected to the first connection port and configured to, when the first connection port is connected to a first signal source, determine whether the mode of the first connection port is a first charging mode or a first discharging mode based on a first channel configuration signal of the first connection port. The charge / discharge control circuit controls the first switching circuit to switch in the first charging mode to enable the first charging path, or controls the second switching circuit to switch in the first discharging mode to enable the first discharging path. The charge / discharge control circuit is also configured to, when the second connection port is connected to a second signal source, receive a second channel configuration signal from the second connection port through the identification terminal to determine whether the mode of the second connection port is a second charging mode or a second discharging mode, and control the third switching circuit to switch in the second charging mode to enable the second charging path, or control the fourth switching circuit to switch in the second discharging mode to enable the second discharging path.

[0006] One of the beneficial effects of the present invention is that the charging and discharging circuit provided by the present invention provides independent charging and discharging paths and independent control mechanisms for the two USB ports respectively, enabling the two USB ports to be used independently and charged and discharged in mobile electronic devices. When both USB ports want to enter the charging mode, control is performed according to a predetermined priority to avoid mutual power supply, while charging the battery module of the mobile electronic device. In addition, it also supports the two USB ports to enter the discharging mode at the same time.

[0007] To further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are for reference and illustration only and are not intended to limit the present invention. Attached Figure Description

[0008] Figure 1This is a circuit layout diagram of a charging and discharging circuit according to an embodiment of the present invention.

[0009] Figure 2 This is a schematic diagram of the charging and discharging path for a first charging and discharging scenario according to an embodiment of the present invention.

[0010] Figure 3 This is a schematic diagram of the charging and discharging path in a second charging and discharging scenario according to an embodiment of the present invention.

[0011] Figure 4 This is a schematic diagram of the charging and discharging path in a third charging and discharging scenario according to an embodiment of the present invention.

[0012] Figure 5 This is a schematic diagram of the charging and discharging path for a fourth charging and discharging scenario according to an embodiment of the present invention.

[0013] Explanation of reference numerals in the attached figures:

[0014] 1: Charging and discharging circuit

[0015] 10: Charge and discharge control circuit

[0016] 11: First connection port

[0017] 12: First switching circuit

[0018] 13: Second switching circuit

[0019] 14: Second connection port

[0020] 15: Third Switching Circuit

[0021] 16: Fourth Switching Circuit

[0022] 17: Identify logic circuits

[0023] 18: First power conversion circuit

[0024] 19: Second power conversion circuit

[0025] 20: Battery Module

[0026] 30: System-side circuit

[0027] Bat: Battery end

[0028] CC1: Identification end

[0029] In1: First input terminal

[0030] In2: Second input terminal

[0031] Out: Output terminal

[0032] Pc1: First charging path

[0033] Pc2: Second charging path

[0034] Pdc1: First discharge path

[0035] Pdc2: Second discharge path

[0036] S1: First signal source

[0037] S2: Second signal source

[0038] Scc1: First channel configuration signal

[0039] Scc2: Second channel configuration signal

[0040] Sm: Mode signal

[0041] Vout: Output voltage Detailed Implementation

[0042] The following specific embodiments illustrate the implementation of the "charging and discharging circuit" disclosed in this invention. Those skilled in the art can understand the advantages and effects of this invention from the content disclosed in this specification. This invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of this invention. Furthermore, the accompanying drawings of this invention are for simple illustrative purposes only and are not depictions of actual dimensions, as stated in advance. The following embodiments will further describe the relevant technical content of this invention in detail, but the disclosed content is not intended to limit the scope of protection of this invention. In addition, the term "or" as used herein may include, depending on the actual situation, any combination of any one or more of the associated listed items.

[0043] Figure 1 This is a circuit layout diagram of a charging and discharging circuit according to an embodiment of the present invention. See also... Figure 1 As shown, this embodiment of the invention provides a charging and discharging circuit 1, which includes a charging and discharging control circuit 10, a first connection port 11, a first switching circuit 12, a second switching circuit 13, a second connection port 14, a third switching circuit 15, a fourth switching circuit 16, and an identification logic circuit 17. In one embodiment, the first connection port 11 and the second connection port 14 may be the same type of connection port, such as a Universal Serial Bus (USB) Type-C connection port. However, it is not limited to this. In one embodiment, the first connection port 12 and the second connection port 22 may also be different types of connection ports, such as a USB Type-A connection port and a USB Type-C connection port.

[0044] The charge / discharge control circuit 10 has a first input terminal In1, a second input terminal In2, an identification terminal CC1, a battery terminal Bat, and an output terminal Out. The battery terminal Bat is connected to the battery module 20, and the output terminal Out is connected to the system circuit 30. For example, the charge / discharge control circuit 10, the battery module 20, and the system circuit 30 can be built into a mobile electronic device. The system circuit 30 can be powered by the battery module 20 through the charge / discharge control circuit 10, and the charge / discharge control circuit 10 can be connected to an external signal source, such as a voltage source, through the first connection port 11 and the second connection port 14 to charge the battery module 20, or to another electronic device that needs to be powered by the aforementioned mobile electronic device.

[0045] For example, the charge / discharge control circuit 10 may be an integrated circuit of a programmable logic controller circuit, a microprocessor circuit, a digital signal processor (DSP), or a microcontroller circuit, but the present invention is not limited thereto.

[0046] Continuing, the first switching circuit 12 is connected between the first connection port 11 and the first input terminal In1 to form the first charging path Pc1. The second switching circuit 13 is connected between the first connection port 11 and the output terminal to form the first discharging path Pdc1.

[0047] On the other hand, the third switching circuit 15 is connected between the second connection port 14 and the second input terminal In2 to form the second charging path Pc2. The fourth switching circuit 16 is connected between the second connection port 14 and the output terminal to form the second discharging path Pdc2.

[0048] For example, the first switching circuit 12, the second switching circuit 13, the third switching circuit 15, and the fourth switching circuit 16 each include a P-type metal-oxide-semiconductor field-effect transistor (PMOSFET) and an N-type metal-oxide-semiconductor field-effect transistor (NMOSFET). In a particular embodiment, the first switching circuit 12, the third switching circuit 15, and the fourth switching circuit 16 further include a current-limiting unit configured to turn off the corresponding PMOSFET and NMOSFET when a rated current is exceeded. For example, the first switching circuit 12, the second switching circuit 13, the third switching circuit 15, and the fourth switching circuit 16 are all power switches to ensure safety and reliability during power supply. The current-limiting unit can safely cut off the power supply in case of overload or overtemperature. The power switch may include a control terminal (e.g., an EN pin) for activating the MOSFET and preventing reverse current through a diode. When the output current of the power switch exceeds the upper current threshold, the current-limiting unit turns off the MOSFET. In a particular embodiment, the power switch may include another terminal to notify the system of a failure when any protection function is triggered. In another embodiment, the charge / discharge control circuit 10 may also provide a current limiting unit for the first input terminal In1 and the second input terminal In2, so as to disconnect the corresponding first input terminal In1 or the second input terminal In2 when the current exceeds a rated current. However, this is only an example and the present invention is not limited thereto.

[0049] The identification logic circuit 17 is connected to the first connection port 11. The identification logic circuit 17 may be, for example, an integrated circuit of a programmable logic controller circuit, a microprocessor circuit, a digital signal processor (DSP), or a micro-control circuit, but the present invention is not limited thereto.

[0050] More specifically, the identification logic circuit 17 is a channel configuration (CC) contact connected to the first connection port 11. When the first connection port 11 is connected to the first signal source S1, the identification logic circuit 17 can establish a corresponding power transmission mode with the first signal source S1 from the external device through the CC contact of the first connection port 11. For example, the master-slave relationship, which device acts as the master device (Host) as the power source, which device acts as the slave device (Slave) as the power sink, and the charging specifications between the charging and discharging control circuit 10 and the first signal source S1.

[0051] When the first connection port 11 is connected to the first signal source S1, the identification logic circuit 17 determines whether the mode of the first connection port 11 is the first charging mode or the first discharging mode based on the first channel configuration signal Scc1 of the first connection port 11, and outputs a mode signal Sm indicating the mode of the first connection port 11 to the charging and discharging control circuit 10 accordingly.

[0052] In detail, in response to the identification logic circuit 17 determining that the first signal source S1 is the host device and the charge / discharge control circuit 10 is the slave device, the identification logic circuit 17 determines that the mode of the first connection port 11 is the first charging mode, that is, the first charging path Pc1 will be used. The identification logic circuit 17 generates a mode signal Sm to inform the charge / discharge control circuit 10 that the first charging path Pc1 needs to be turned on.

[0053] Conversely, in response to the identification logic circuit 17 determining that the first signal source S1 is a slave device and the charge / discharge control circuit 10 is a master device, the identification logic circuit 17 determines that the mode of the first connection port 11 is the first discharge mode, in other words, the first discharge path Pdc1 will be used. The identification logic circuit 17 generates a mode signal Sm to inform the charge / discharge control circuit 10 that the first discharge path Pdc1 needs to be turned on.

[0054] Furthermore, when the charge / discharge control circuit 10 receives the mode signal Sm, it controls the first switch circuit 12 to switch in the first charging mode or the first discharging mode according to whether the first connection port 11 indicated by the mode signal Sm is in the first charging mode or the first discharging mode, so as to turn on the first charging path Pc1 in the first charging mode, or controls the second switch circuit 13 to switch in the first discharging mode so as to turn on the first discharging path Pdc1.

[0055] Similarly, the charge / discharge control circuit 10 is connected to the second connection port 14 and also has a similar identification mechanism. When the second connection port 14 is connected to the second signal source S2, the charge / discharge control circuit 10 receives the second channel configuration signal Scc2 from the second connection port 14 through the identification terminal CC1, so as to determine whether the mode of the second connection port 14 is the second charging mode or the second discharging mode.

[0056] In detail, the charge / discharge control circuit 10 is connected to the Channel Configuration (CC) contact of the second connection port 14. When the second connection port 14 is connected to the second signal source S2, the charge / discharge control circuit 10 can establish a corresponding power transmission mode with the second signal source S2 from the external device through the CC contact of the second connection port 14. For example, the master-slave relationship, which device acts as the master device (Host) as the power supply end (source), which device acts as the slave device (Slave) as the power receiving end (sink), and the charging specifications between the charge / discharge control circuit 10 and the second signal source S2, etc.

[0057] When the second connection port 14 is connected to the second signal source S2, the charge and discharge control circuit 10 can determine the master-slave relationship between the second signal source S2 and the charge and discharge control circuit based on the second channel configuration signal Scc2, so as to determine whether the mode of the second connection port 14 is the second charging mode or the second discharging mode. In this way, the charge and discharge control circuit 10 can control the third switch circuit 15 and the fourth switch circuit 16 to switch so that the second charging path Pc2 is turned on or the second discharging path Pdc2 is turned on.

[0058] For example, in response to the charge / discharge control circuit 10 determining that the second signal source S2 is the master device and the charge / discharge control circuit 10 is the slave device, the charge / discharge control circuit 10 determines that the mode of the second connection port 14 is the second charging mode, in other words, the second charging path Pc2 will be used.

[0059] Conversely, in response to the charge / discharge control circuit 10 determining that the second signal source S2 is a slave device and the charge / discharge control circuit 10 is a master device, the charge / discharge control circuit 10 determines that the mode of the second connection port 14 is the second discharge mode, in other words, the second discharge path Pdc2 will be used.

[0060] In addition, Figure 1 In this embodiment, the charging / discharging circuit 1 further includes a first power conversion circuit 18 and a second power conversion circuit 19. The first power conversion circuit 18 is connected between the second switching circuit 13 and the output terminal Out1, and the second power conversion circuit 19 is connected between the fourth switching circuit 16 and the output terminal Out. The first power conversion circuit 18 is configured to perform power conversion on an output voltage Vout at the output terminal when the first discharge path is on, and the second power conversion circuit 19 is configured to perform power conversion on the output voltage Vout when the second discharge path is on.

[0061] For example, the first power conversion circuit 18 and the second power conversion circuit 19 can be a boost power converter, a buck power converter, or a buck-boost power converter. The type used is determined based on the output voltage Vout provided by the charge / discharge control circuit 10, the rated voltage of the battery module 20, and the voltage to be output to the first connection port 11 and the second connection port 14, in order to boost or buck the output voltage. The above are merely examples, and the present invention is not limited thereto.

[0062] However, as described above, in order to avoid power leakage caused by simultaneous charging or the inability of a later-inserted USB port to function properly, the charging and discharging circuit 1 provided by this invention has different control methods for different situations.

[0063] For reference Figure 2 This is a schematic diagram of the charging and discharging path in a first charging and discharging scenario according to an embodiment of the present invention. In the first charging and discharging scenario, the first signal source S1 and the second signal source S2 can be, for example, adapters, both of which can provide power to the battery module 20. Therefore, the charging and discharging control circuit 10 determines that the mode of the second connection port 14 is the second charging mode, and according to the mode signal Sm, it knows that the first connection port 11 is determined by the identification circuit 17 to be in the first charging mode. The charging and discharging control circuit 10 is configured to control the first switching circuit 12 and the third switching circuit 15 according to a predetermined priority sequence preset by the user, so that one of the first charging path Pc1 and the second charging path Pc2 is turned on and the other is turned off.

[0064] by Figure 2 In this embodiment, the predetermined priority is to use the second connection port 14 first. Therefore, the charge / discharge control circuit 10 controls the first switch circuit 12 to turn off and the third switch circuit 15 to turn on, so that the first charging path Pc1 is turned off and the second charging path Pc2 is turned on. At the same time, when the second charging path Pc2 is turned on, the charge / discharge control circuit 10 charges the battery module 20 through the battery terminal Bat.

[0065] Furthermore, it should be noted that the first charging path Pc1 and the first discharging path Pdc1 are mutually exclusive; when one is on, the other is off. Similarly, the second charging path Pc2 and the second discharging path Pdc2 are mutually exclusive. Therefore, in the first charging and discharging scenario, the charging and discharging control circuit 10 also controls the second switching circuit 13 and the fourth switching circuit 16 to be turned off, so that both the first discharging path Pdc1 and the second discharging path Pdc2 are turned off.

[0066] For reference Figure 3This is a schematic diagram of the charging and discharging path in a second charging and discharging scenario according to an embodiment of the present invention. In the second charging and discharging scenario, the first signal source S1 is another electronic device that needs to be powered, and the second signal source S2 is an adapter that can provide power to the battery module 20. Therefore, the charging and discharging control circuit 10 determines that the mode of the second connection port 14 is the second charging mode, and according to the mode signal Sm, it knows that the first connection port 11 is determined by the identification circuit 17 to be in the first discharging mode. The charging and discharging control circuit 10 controls the second switch circuit 12 and the third switch circuit 15 to be turned on, so that the first discharging path Pdc1 is turned on and the second charging path Pc2 is turned on. At the same time, when the second charging path Pc2 is turned on, the charging and discharging control circuit 10 charges the battery module 20 through the battery terminal Bat. In addition, in the second charging and discharging scenario, the charging and discharging control circuit 10 also controls the first switch circuit 12 and the fourth switch circuit 16 to be turned off, so that the first charging path Pdc1 and the second discharging path Pdc2 are both turned off.

[0067] For reference Figure 4 This is a schematic diagram of the charging and discharging path in a third charging and discharging scenario according to an embodiment of the present invention. In the third charging and discharging scenario, the first signal source S1 is an adapter that can provide power to the battery module 20, while the second signal source S2 is another electronic device that needs to be powered. Therefore, the charging and discharging control circuit 10 determines that the mode of the second connection port 14 is the second discharging mode, and according to the mode signal Sm, it knows that the first connection port 11 is determined by the identification circuit 17 to be in the first charging mode. The charging and discharging control circuit 10 controls the first switch circuit 12 and the fourth switch circuit 16 to be turned on, so that the first charging path Pc1 is turned on and the second discharging path Pdc2 is turned on. At the same time, when the first charging path Pc1 is turned on, the charging and discharging control circuit 10 charges the battery module 20 through the battery terminal Bat. In addition, in the third charging and discharging scenario, the charging and discharging control circuit 10 also controls the second switch circuit 13 and the third switch circuit 15 to be turned off, so that the first discharging path Pdc1 and the second charging path Pc2 are both turned off.

[0068] Figure 5This is a schematic diagram of the charging and discharging path in a fourth charging and discharging scenario according to an embodiment of the present invention. In the fourth charging and discharging scenario, both the first signal source S1 and the second signal source S2 are electronic devices that need to be powered. Therefore, the charging and discharging control circuit 10 determines that the mode of the second connection port 14 is the second discharging mode, and based on the mode signal Sm, it knows that the first connection port 11 is determined by the identification circuit 17 to be in the first discharging mode. The charging and discharging control circuit 10 controls the second switch circuit 13 and the fourth switch circuit 16 to be turned on, so that the first discharging path Pdc1 is turned on and the second discharging path Pdc2 is turned on. At the same time, when both the first discharging path Pdc1 and the second discharging path Pdc2 are turned on, the battery module 20 charges the first signal source S1 and the second signal source S2 through the battery terminal Bat. In addition, in the third charging and discharging scenario, the charging and discharging control circuit 10 also controls the first switch circuit 12 and the third switch circuit 15 to be turned off, so that both the first charging path Pc1 and the second charging path Pc2 are turned off.

[0069] [Beneficial Effects of the Examples]

[0070] One of the advantages of the present invention is that the charging and discharging circuit provided by the present invention, by providing independent charging and discharging paths and independent control mechanisms for the two USB ports respectively, enables the two USB ports to be used independently and charged and discharged in mobile electronic devices.

[0071] Furthermore, the charging and discharging circuit provided by this invention controls the charging according to a predetermined priority order when both USB ports want to enter the charging mode to avoid mutual power supply, while charging the battery module of the mobile electronic device. In addition, it also supports both USB ports entering the discharging mode at the same time.

[0072] The content disclosed above is only a preferred and feasible embodiment of the present invention, and is not intended to limit the claims of the present invention. Therefore, all equivalent technical changes made based on the content of the present invention specification and drawings are included within the scope of the claims of the present invention.

Claims

1. A charging and discharging circuit connecting a battery module and a system terminal circuit, the charging and discharging circuit comprising: A charging and discharging control circuit has a first input terminal, a second input terminal, an identification terminal, a battery terminal and an output terminal, wherein the battery terminal is connected to the battery module and the output terminal is connected to the system terminal circuit. First connection port; A first switching circuit is connected between the first connection port and the first input terminal to form a first charging path; A second switching circuit is connected between the first connection port and the output terminal to form a first discharge path; A second connection port; A third switching circuit is connected between the second connection port and the second input terminal to form a second charging path; A fourth switching circuit is connected between the second connection port and the output terminal to form a second discharge path; as well as An identification logic circuit, connected to the first connection port, is configured to determine, based on a first channel configuration signal of the first connection port, whether the first connection port is in a first charging mode or a first discharging mode when the first connection port is connected to a first signal source. The charging / discharging control circuit controls the first switching circuit to switch in the first charging mode to enable the first charging path, or controls the second switching circuit to switch in the first discharging mode to enable the first discharging path. The charging / discharging control circuit is also configured to receive a second channel configuration signal from the second connection port via the identification terminal when the second connection port is connected to a second signal source, to determine whether the second connection port is in a second charging mode or a second discharging mode. In the second charging mode, the circuit controls the third switching circuit to switch in the second charging mode to enable the second charging path, or in the second discharging mode, the circuit controls the fourth switching circuit to switch in the second discharging mode to enable the second discharging path. The first charging path, the second charging path, the first discharging path, and the second discharging path are independent of each other.

2. The charging and discharging circuit of claim 1, wherein the identification logic circuit is configured to output a mode signal indicating the mode of the first connection port to the charging and discharging control circuit when determining that the mode of the first connection port is the first charging mode or the first discharging mode.

3. The charging and discharging circuit as described in claim 1, wherein, In response to the first connection port being determined to be in the first charging mode and the second connection port being determined to be in the second charging mode, the charge / discharge control circuit is configured to control the first switching circuit and the third switching circuit according to a predetermined priority order, so that one of the first charging path and the second charging path is turned on and the other is turned off.

4. The charging and discharging circuit as described in claim 1, further comprising: A first power conversion circuit is connected between the second switching circuit and the output terminal; and A second power conversion circuit is connected between the fourth switching circuit and the output terminal. The first power conversion circuit is configured to convert the power supply of an output voltage at the output terminal when the first discharge path is turned on, and the second power conversion circuit is configured to convert the power supply of the output voltage when the second discharge path is turned on.

5. The charging and discharging circuit as claimed in claim 1, wherein the identification logic circuit is further configured to determine the master-slave relationship between the first signal source and the charging and discharging control circuit based on the first channel configuration signal, so as to determine whether the mode of the first connection port is the first charging mode or the first discharging mode.

6. The charging and discharging circuit as described in claim 5, wherein, In response to the identification logic circuit determining that the first signal source is a master device and the charge / discharge control circuit is a slave device, the identification logic circuit determines that the mode of the first connection port is the first charging mode, and generates a corresponding mode signal. In response to the identification logic circuit determining that the first signal source is the slave device and the charging / discharging control circuit is a master device, the identification logic circuit determines that the mode of the first connection port is the first discharge mode, and generates the corresponding mode signal.

7. The charging and discharging circuit as claimed in claim 1, wherein the charging and discharging control circuit is further configured to determine the master-slave relationship between the second signal source and the charging and discharging control circuit based on the second channel configuration signal, so as to determine whether the mode of the second connection port is the second charging mode or the second discharging mode.

8. The charging and discharging circuit as described in claim 7, wherein, In response to the charging and discharging control circuit determining that the second signal source is a master device and the charging and discharging control circuit is a slave device, and the charging and discharging control circuit determining that the mode of the second connection port is the second charging mode, in response to the charging and discharging control circuit determining that the second signal source is the slave device and the charging and discharging control circuit is the master device, and the charging and discharging control circuit determining that the mode of the second connection port is the second discharging mode.

9. The charging and discharging circuit as described in claim 1, wherein, The charge / discharge control circuit is configured to charge the battery module through the battery terminal when the first charging path or the second charging path is open.

10. The charging and discharging circuit as described in claim 1, wherein, In response to the first connection port being determined to be in the first discharge mode and the second connection port being determined to be in the second discharge mode, the charge / discharge control circuit is configured to control the second switch circuit and the fourth switch circuit so that the first discharge path and the second discharge path are simultaneously turned on.

11. The charging and discharging circuit as claimed in claim 1, wherein each of the first to fourth switching circuits includes a P-type metal-oxide-semiconductor field-effect transistor and an N-type metal-oxide-semiconductor field-effect transistor.

12. The charging and discharging circuit of claim 11, wherein each of the second to fourth switching circuits further includes a current limiting unit configured to turn off the corresponding P-type metal-oxide-semiconductor field-effect transistor and the N-type metal-oxide-semiconductor field-effect transistor when a rated current is exceeded.

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