Charging and discharging circuit, electronic equipment, system and common-mode voltage adjusting method

Abstract

The invention discloses a charging and discharging circuit, electronic equipment, a system and a common-mode voltage regulation method. The charging and discharging circuit comprises a voltage detection circuit, a transmitter and a common-mode compensation circuit, a configuration channel of the charging and discharging circuit is connected with opposite terminal equipment, and an interface corresponding to the configuration channel is located at the Type-C interface; the voltage detection circuit samples the common-mode voltage of the configuration channel and sends the common-mode voltage to the common-mode compensation circuit under the condition that the charging and discharging circuit establishes communication with opposite-end equipment; the transmitter outputs a sending signal sent to opposite-end equipment; the common-mode compensation circuit adjusts a sending signal of the transmitter according to a comparison result of the common-mode voltage and a voltage reference value, and outputs the adjusted sending signal to the configuration channel; the voltage reference value is obtained when the charging and discharging circuit and the opposite-end equipment are connected for the first time and no current is transmitted. According to the scheme, the common-mode voltage can be adaptively adjusted, and the accuracy of the CC signal transmitted between the transmitting end and the receiving end is improved.

Description

Technical Field

[0001] This application relates to the technical field of data processing, and in particular, to a charging and discharging circuit, an electronic device, a system, and a common-mode voltage regulation method. Background Art

[0002] Many communication and charging interfaces of electronic devices adopt the Type-C interface. The Type-C interface adopts a symmetrical design with upper and lower sides, and the socket is flat and rectangular.

[0003] With the application of the Type-C interface, Power Delivery (PD) communication in fast charging technology has become increasingly important. However, as the PD power increases, the online loss of the Type-C cable also becomes larger, resulting in a large difference in the ground level between the PD devices at the sending end and the receiving end. When the sending end and the receiving end perform PD communication, the common-mode voltage difference between the sending end and the receiving end on the Configuration Channel (CC) line is relatively large, thus affecting the reception of the CC signal. Summary of the Invention

[0004] In view of this, the embodiments of this application provide a charging and discharging circuit, an electronic device, a system, and a common-mode voltage regulation method, which can adaptively adjust the common-mode voltage and improve the accuracy of the CC signal transmitted between the sending end and the receiving end.

[0005] The embodiments of this application provide a charging and discharging circuit. The charging and discharging circuit is located at the charging end or the power receiving end, and the charging and discharging circuit includes: a voltage detection circuit, a transmitter, and a common-mode compensation circuit; the configuration channel of the charging and discharging circuit is used to connect to the peer device, and the interface corresponding to the configuration channel is located at the Type-C interface; when the charging and discharging circuit is located at the charging end, the peer device is the power receiving end; when the charging and discharging circuit is located at the power receiving end, the peer device is the charging end; the voltage detection circuit is used to sample the common-mode voltage of the configuration channel and send the common-mode voltage to the common-mode compensation circuit when the charging and discharging circuit establishes communication with the peer device; the transmitter is used to output a transmission signal sent to the peer device; the common-mode compensation circuit is used to adjust the transmission signal of the transmitter according to the comparison result between the common-mode voltage and the voltage reference value, and output the adjusted transmission signal to the configuration channel; the voltage reference value is obtained when the charging and discharging circuit and the peer device are first connected and there is no current transfer.

[0006] In a possible implementation, the voltage detection circuit is further used to sample the initial common-mode voltage of the configuration channel as the voltage reference value when the charging and discharging circuit is first connected to the peer device and the charging and discharging circuit does not establish communication with the peer device.

[0007] A possible implementation, the common-mode compensation circuit is used to superimpose the difference between the common-mode voltage and the voltage reference value on the transmission signal to obtain an adjusted transmission signal.

[0008] A possible implementation, when the charge and discharge circuit is located at the power receiving end, when the charging end charges the power receiving end, the common-mode voltage detected by the voltage detection circuit is less than the voltage reference value.

[0009] A possible implementation, when the charge and discharge circuit is located at the charging end, when the charging end charges the power receiving end, the common-mode voltage detected by the voltage detection circuit is greater than the voltage reference value.

[0010] A possible implementation, the common-mode compensation circuit is integrated inside the controller of the charge and discharge circuit.

[0011] The embodiment of the present application further provides an electronic device, including the charge and discharge circuit introduced above; the electronic device is a charging end or a power receiving end.

[0012] A possible implementation, the electronic device is a charger or a display.

[0013] The embodiment of the present application further provides a communication system, including the electronic device introduced above, and further including a peer device; when the electronic device is a charging end, it is used to charge the peer device; when the electronic device is a power receiving end, it is used to be charged by the peer device.

[0014] The embodiment of the present application further provides a common-mode voltage regulation method, including: sampling the common-mode voltage of the configuration channel of the charge and discharge circuit when the charge and discharge circuit establishes communication with the charging end; adjusting the transmission signal of the transmitter according to the comparison result between the common-mode voltage and the voltage reference value, and outputting the adjusted transmission signal to the configuration channel.

[0015] Thus, the embodiment of the present application has the following beneficial effects: The charge and discharge circuit provided by the embodiment of the present application, when applied to the charge and discharge circuit, can first detect the common-mode voltage of the configuration channel before the charging end and the power receiving end communicate, compare it with the voltage reference value, and adjust the magnitude of the transmission signal according to the comparison result, so that the transmission signal can be adaptively adjusted based on the detected common-mode level to ensure that the compensated signal sent to the peer device is the correct signal. Description of the Drawings

[0016] Figure 1 It is a schematic diagram of a charge and discharge circuit provided by an embodiment of the present application; Figure 2 It is a signal schematic diagram of a traditional charging end and a power receiving end; Figure 3 A signal schematic diagram of a charging end and a power receiving end provided by an embodiment of the present application; Figure 4 A schematic diagram of an electronic device provided by an embodiment of the present application; Figure 5 A schematic diagram of a communication system provided by an embodiment of the present application; Figure 6 A flowchart of a common mode voltage regulation method provided by an embodiment of the present application. Detailed implementation manners

[0017] To make the above objects, features, and advantages of the present application more obvious and understandable, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0018] The interface corresponding to the configuration channel CC is located on the Type-C interface.

[0019] The charging and discharging circuit provided by the embodiment of the present application is not limited to specific existing application scenarios. For example, it can be located in any electronic device using a Type-C interface. The charging and discharging circuit can be located at the charging end, and the charging end charges other devices. The charging and discharging circuit can also be located at the power receiving end, and the power receiving end is charged by other devices.

[0020] Since the charging end performs power transmission and information interaction with the power receiving end, when the common mode voltages of the charging end and the power receiving end are quite different, it may cause the signals of the two-way communication to be misrecognized by the other party. For example, 1 is recognized as 0, 0 is recognized as 1, etc.

[0021] The charging end can be a charger or other devices with a Type-C interface. For example, the charging end can be a desktop computer or a monitor, etc. The power receiving end can be a mobile phone or a laptop computer, etc.

[0022] Since the common mode voltage sent by the configuration channel CC in the related art is a fixed level, in different application scenarios, it is impossible to adjust the common mode voltage output by the configuration channel CC according to the actual loss, resulting in abnormal communication for the PD device at the opposite end because it cannot normally obtain the data of the configuration channel CC. Especially after the PD3.1 standard, the PD communication data volume and the online power are getting larger and larger, the line loss is getting higher and higher, and the problem of abnormal communication is more prominent.

[0023] To solve the above technical problems, the embodiment of the present application provides a charging and discharging circuit, which can detect the common mode voltage of the configuration channel before the charging end and the power receiving end communicate, compare it with the voltage reference value, and adjust the magnitude of the transmitted signal according to the comparison result, so that the transmitted signal can be adaptively adjusted based on the detected common mode level to ensure the normal reception of the signal by the device at the opposite end.

[0024] See Figure 1 , which is a schematic diagram of a charging and discharging circuit provided by an embodiment of the present application.

[0025] The charging and discharging circuit 100 provided by the embodiment of the present application can be located at the charging end or the power receiving end. The charging and discharging circuit 100 includes: a voltage detection circuit 10, a transmitter TX, and a common-mode compensation circuit 20.

[0026] The configuration channel CC of the charging and discharging circuit is used to connect to the peer device, and the interface corresponding to the configuration channel CC is located at the Type-C interface; when the charging and discharging circuit is located at the charging end, the peer device is the power receiving end; when the charging and discharging circuit is located at the power receiving end, the peer device is the charging end.

[0027] The voltage detection circuit 10 is used to sample the common-mode voltage of the configuration channel CC and send the common-mode voltage to the common-mode compensation circuit 20 when the charging and discharging circuit establishes communication with the peer device. When the charging end and the power receiving end are connected through the Type-C interface, both parties will perform PD handshake communication through the configuration channel CC according to the requirements of the PD protocol.

[0028] It should be understood that when the charging end charges the device to be charged, a large charging current will flow through the Type-C cable. Since the cable has internal resistance, and the internal resistance is related to the material and length of the Type-C cable, there is a difference in the ground level between the charging end and the device to be charged, which in turn affects the difference in the common-mode voltage between the charging end and the device to be charged. Moreover, the common-mode level of the charging end is higher than that of the power receiving end.

[0029] The common-mode compensation circuit 20 is used to adjust the transmission signal of the transmitter TX according to the comparison result between the common-mode voltage and the voltage reference value, and output the adjusted transmission signal to the configuration channel C; the voltage reference value is obtained when the charging and discharging circuit and the peer device are first connected and there is no current transfer.

[0030] The voltage reference value is the common-mode voltage detected when the charging end and the power receiving end are first connected and in the idle state. When first connected, the current consumption is very low, and at this time the common-mode voltage is used as the voltage reference value; during the idle state, the common-mode voltage is in a stable state, which is convenient for the detection of the common-mode voltage. Therefore, the voltage reference value can be detected in the idle state.

[0031] After the charging end and the power receiving end establish communication, the current increases and the power consumption increases. At this time, the internal resistance loss increases, resulting in a lower and lower common-mode voltage of the configuration channel CC. At this time, when the charge and discharge circuit is at the power receiving end, the common-mode level detected by the voltage detection circuit is the common-mode level after being reduced due to the loss, and the detected common-mode level is lower than the common-mode level of the charging end. Due to the difference in the common-mode levels between the charging end and the power receiving end, it may cause incorrect recognition of the communication signals between the charging end and the power receiving end.

[0032] The charge and discharge circuit provided in the embodiment of the present application further includes a receiver RX. The first input end of the receiver RX is used to connect to the configuration channel CC, and the second input end of the receiver RX is connected to the reference voltage Vref. The receiver RX is used to receive the signal sent by the peer device through the configuration channel CC, and output it after comparing with the reference voltage Vref. For example, it can be output to a buffer for data caching.

[0033] For easy understanding, the following will be introduced in detail with reference to the drawings.

[0034] See Figure 2 , which is a signal schematic diagram of the traditional charging end and power receiving end.

[0035] Figure 2 shows the signal sent from one end where the charge and discharge circuit is located, and the signal sent from one end of the charge and discharge circuit detected by the peer device. Figure 2 It also shows the signal sent by the peer device and the signal of the peer device detected by one end of the charge and discharge circuit.

[0036] Figure 2 The 2 pairs of waveforms in are divided according to the charging current and all include three situations: no current, current reverse, and normal current. No current means that the charging end and the power receiving end have not started charging and no current flows through. Current reverse means that one end of the charge and discharge circuit charges the peer device. Current forward means that the peer device charges one end of the charge and discharge circuit.

[0037] The following will analyze the signals according to the above current directions: The first situation of no current: It can be seen that when there is no charging current between the power receiving end and the charging end, when the peer device sends a signal, the signal of the peer device detected by the end where the charge and discharge circuit is located will not have an error and retains the original appearance of the signal sent by the peer device. Similarly, when the charge and discharge circuit sends a signal, the signal of the charge and discharge circuit detected by the peer device also retains the original appearance of the signal sent by the charge and discharge circuit, and no abnormality occurs.

[0038] The second current reverse: Since the direction of the charging current causes the common-mode voltage at the power receiving end to be lower than that at the charging end, the signal sent by the opposite-end device detected by the charge and discharge circuit is increased compared to the original signal, and all are above the horizontal axis, that is, the signal of the opposite end detected by the charge and discharge circuit is larger than the signal actually sent by the opposite-end device. And the signal sent by the charge and discharge circuit detected by the opposite-end device is smaller than the actual signal sent.

[0039] The third current forward: Since the direction of the charging current causes the common-mode voltage at the power receiving end to be lower than that at the charging end, the signal sent by the opposite-end device detected by the charge and discharge circuit is decreased compared to the original signal, and some are below the horizontal axis, that is, the signal of the opposite end detected by the charge and discharge circuit is smaller than the signal actually sent by the opposite-end device. And the signal sent by the charge and discharge circuit detected by the opposite-end device is larger than the actual signal sent, and all are above the horizontal axis.

[0040] From Figure 2 it can be seen that when the current is forward and reverse in the charge and discharge circuit, that is, regardless of whether the charge and discharge circuit is located at the charging end or the power receiving end, the signal sent by the charge and discharge circuit detected by the opposite-end device is not the real signal and there is an offset. Therefore, in order to enable the opposite-end device to obtain the real signal, before sending the signal through the configuration channel CC, the charge and discharge circuit provided in the embodiment of the present application first compensates the signal internally to compensate for the signal drift caused by the mismatch of the common-mode voltages at both ends, so that the signal received by the opposite-end device is the real signal of the charge and discharge circuit.

[0041] See Figure 3 , which is a signal schematic diagram of a charging end and a power receiving end provided in the embodiment of the present application.

[0042] The charge and discharge circuit provided in the embodiment of the present application, from Figure 3 by comparison Figure 2 it can be seen that the signal sent by the charge and discharge circuit is the compensated signal, that is, the signals sent by the TX in the charge and discharge circuit are all signals based on the horizontal axis, Figure 2 directly sends the signal sent by the TX through the CC to the opposite-end device in Figure 3 . However, the charge and discharge circuit provided in the embodiment of the present application will send the signal sent by the TX after compensation through the CC to the opposite-end device. The function of the common-mode compensation circuit is to compensate for the signal difference changed due to the loss.

[0043] The voltage detection circuit provided in the embodiment of the present application is further used to sample the initial common-mode voltage of the configuration channel as the voltage reference value when the charge and discharge circuit is first connected to the opposite-end device and communication has not been established between the charge and discharge circuit and the opposite-end device.

[0044] A common-mode compensation circuit is used to superimpose the difference between the common-mode voltage and the voltage reference value on the transmitted signal to obtain an adjusted transmitted signal. It should be understood that when the charging current directions at the charging end and the power receiving end are different, the difference between the common-mode voltage and the voltage reference value is sometimes positive and sometimes negative.

[0045] For example, when the charging and discharging circuit is located at the power receiving end, when the charging end charges the power receiving end, the common-mode voltage detected by the voltage detection circuit is less than the voltage reference value.

[0046] For example, when the charging and discharging circuit is located at the charging end, when the charging end charges the power receiving end, the common-mode voltage detected by the voltage detection circuit is greater than the voltage reference value.

[0047] The charging and discharging circuit provided in the embodiment of the present application does not specifically limit the specific implementation form of the common-mode compensation circuit. For example, it can be an independent circuit with voltage compensation function, or it can be implemented by a controller, that is, the common-mode compensation circuit is integrated inside the controller of the charging and discharging circuit.

[0048] First, the case where the charging and discharging circuit is located at the charging end will be introduced below.

[0049] Taking the charging and discharging circuit located in the charger and the peer device being a laptop computer as an example, the two are connected through a Type-c cable and a Type-c interface. Both parties will initiate PD handshake communication through the CC channel according to the requirements of the PD protocol.

[0050] Because there is internal resistance in the Type-C cable, voltage loss is generated, resulting in a voltage difference between the ground levels of the charger and the power receiving end, thereby causing a voltage difference in the common-mode level between the charger and the power receiving end, and the common-mode level of the charger is higher than that of the power receiving end.

[0051] When the charger and the power receiving end establish a connection in the initial currentless state, the charger is in the idle state (currentless state). During the idle state, the current consumption is very small. The voltage detection circuit starts to detect the common-mode voltage of the configuration channel CC during the idle state as the voltage reference value.

[0052] During the actual charging process, there is a charging current between the two, and the charging power increases. Because the voltage loss caused by the internal resistance becomes larger and larger, the common-mode level of the configuration channel CC of the charging and discharging circuit will become higher and higher, and the voltage detection circuit detects the common-mode voltage of the configuration channel CC.

[0053] The common-mode compensation circuit obtains the difference between the voltage reference value and the common-mode voltage, and this difference is the common-mode voltage difference of the configuration channel CC between the charger and the power receiving end caused by the wire loss.

[0054] The common-mode compensation circuit compensates the transmission signal of TX according to the above difference to control the common-mode level of the configuration channel CC, so as to ensure that the signal received by the power receiving end is an accurate signal.

[0055] Next, an example will be given with the charge and discharge circuit located at the power receiving end.

[0056] Taking the charge and discharge circuit located at the power receiving end and the charger as the peer device as an example, the two are connected through a Type-c cable and a Type-c interface. Both parties will initiate PD handshake communication through the CC channel according to the requirements of the PD protocol.

[0057] Because there is internal resistance in the Type-C cable, voltage loss occurs, resulting in a voltage difference between the ground levels of the charger and the charge and discharge circuit, thereby causing a voltage difference in the common-mode level between the charger and the charge and discharge circuit, and the common-mode level of the charger is higher than that of the charge and discharge circuit.

[0058] When the charger and the charge and discharge circuit are initially connected in a no-current state, the charger is in the idle state (no-current state). During the first connection, the current consumption is very low, and at this time, the common-mode voltage is used as the voltage reference value; the common-mode voltage is in a stable state during the idle state, which is convenient for the detection of the common-mode voltage. Therefore, the voltage reference value can be detected in the idle state.

[0059] During the actual charging process, there is a charging current between the two, and the charging power increases. Because the voltage loss caused by the internal resistance is getting larger and larger, the common-mode level of the configuration channel CC of the charge and discharge circuit will become lower and lower, and the voltage detection circuit detects the common-mode voltage of the configuration channel CC.

[0060] The common-mode compensation circuit obtains the difference between the voltage reference value and the common-mode voltage, and this difference is the common-mode voltage difference of the configuration channel CC between the charger and the power receiving end caused by the wire loss.

[0061] The common-mode compensation circuit compensates the transmission signal of TX according to the above difference to control the common-mode level of the configuration channel CC, so as to ensure that the signal received by the power receiving end is an accurate signal.

[0062] Based on the charge and discharge circuit provided in the above embodiments, the embodiments of the present application further provide an electronic device, which will be introduced in detail below with reference to the drawings.

[0063] See Figure 4 , this figure is a schematic diagram of an electronic device provided by the embodiments of the present application.

[0064] The electronic device 1000 provided by the embodiments of the present application includes the charge and discharge circuit 100 introduced in the above embodiments; the electronic device 1000 can be a charging end or a power receiving end, can charge the peer device, or can be charged by the peer device.

[0065] The embodiments of the present application do not specifically limit the type of the electronic device. For example, in one possible implementation, the electronic device 1000 can be a charger or a display.

[0066] Since the signal is compensated in the charge and discharge circuit of the electronic device provided by the embodiments of the present application, it is possible to ensure that the signal at the receiving end of the peer device makes up for the signal difference caused by the loss, and it is possible to ensure the quality of signal communication and ensure normal communication.

[0067] Based on the charge and discharge circuit and the electronic device provided in the above embodiments, the embodiments of the present application further provide a communication system, which will be introduced in detail below with reference to the accompanying drawings.

[0068] See Figure 5 , which is a schematic diagram of a communication system provided by the embodiments of the present application.

[0069] The communication system 2000 provided by the embodiments of the present application includes the electronic device 1000 provided in the above embodiments, and further includes a peer device 200; wherein the electronic device 1000 includes the charge and discharge circuit 100 introduced in the above embodiments.

[0070] When the electronic device 1000 is a charging end, it is used to charge the peer device 200; When the electronic device 1000 is a power receiving end, it is used to be charged by the peer device 200.

[0071] The embodiments of the present application do not specifically limit the type of the device to be charged. For example, the device to be charged is a laptop or a display. When the charging end is a charger or a large display, the device to be charged can be a small display or a laptop, etc.

[0072] Based on the charge and discharge circuit, the electronic device and the communication system provided in the above embodiments, the embodiments of the present application further provide a common mode voltage regulation method, which will be introduced in detail below with reference to the accompanying drawings.

[0073] See Figure 6 , which is a flowchart of a common mode voltage regulation method provided by the embodiments of the present application.

[0074] The common mode voltage regulation method provided by the embodiments of the present application includes: S601: When the charge and discharge circuit establishes communication with the charging end, sample the common mode voltage of the configuration channel of the charge and discharge circuit.

[0075] S602: Adjust the transmission signal of the transmitter according to the comparison result between the common-mode voltage and the voltage reference value, and output the adjusted transmission signal to the configuration channel.

[0076] The common-mode voltage regulation method provided by the embodiments of the present application is applied to the charging and discharging circuit. Before communication between the charging end and the power receiving end, the common-mode voltage of the configuration channel can be detected first, compared with the voltage reference value, and the magnitude of the transmission signal can be adjusted according to the comparison result, so that the transmission signal can be adaptively adjusted based on the detected common-mode level to ensure that the compensated signal sent to the peer device is a correct signal.

[0077] It should be noted that the embodiments in this specification are described in a progressive manner. The key point of each embodiment is the difference from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system or device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0078] It should be understood that in the present application, "at least one (item)" means one or more, and "a plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships can exist. For example, "A and / or B" can mean: only A exists, only B exists, and both A and B exist at the same time. Among them, A and B can be singular or plural. The character " / " generally means that the associated objects before and after are in an "or" relationship. "At least one (one) of the following" or its similar expression refers to any combination of these items, including any combination of single item (one) or plural items (ones). For example, at least one (one) of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0079] It should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of another identical element in the process, method, article or device including the said element.

[0080] The steps of the methods or algorithms described in connection with the embodiments disclosed herein may be implemented directly in hardware, in software modules executed by a processor, or in a combination thereof. The software modules may be located in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium well known in the art.

[0081] The foregoing description of the disclosed embodiments enables those skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A charging and discharging circuit, characterized in that: The charging and discharging circuit is located at the charging end or the receiving end, and the charging and discharging circuit includes: a voltage detection circuit, a transmitter and a common mode compensation circuit; The configuration channel of the charging and discharging circuit is used to connect to the opposite device, and the interface corresponding to the configuration channel is located at the Type-C interface; when the charging and discharging circuit is located at the charging end, the opposite device is the receiving end; when the charging and discharging circuit is located at the receiving end, the opposite device is the charging end; The voltage detection circuit is used to sample the common mode voltage of the configuration channel and send the common mode voltage to the common mode compensation circuit when the charging and discharging circuit establishes communication with the opposite device; The transmitter is used to output a transmission signal to be sent to the opposite end device; The common-mode compensation circuit is used to adjust the transmission signal of the transmitter according to the comparison result of the common-mode voltage and the voltage reference value, and output the adjusted transmission signal to the configuration channel; the voltage reference value is obtained when the charging and discharging circuit and the opposite device are connected for the first time and no current is transmitted.

2. The charge and discharge circuit according to claim 1, characterized in that: The voltage detection circuit is further used to sample the initial common mode voltage of the configuration channel as the voltage reference value when the charging and discharging circuit is connected to the opposite device for the first time and communication between the charging and discharging circuit and the opposite device has not been established.

3. The charge and discharge circuit according to claim 1 or 2, characterized in that: The common-mode compensation circuit is used to superimpose the difference between the common-mode voltage and the voltage reference value on the transmission signal to obtain an adjusted transmission signal.

4. The charge and discharge circuit according to claim 1 or 2, characterized in that: When the charging and discharging circuit is located at the power receiving end, when the charging end charges the power receiving end, the common mode voltage detected by the voltage detection circuit is smaller than the voltage reference value.

5. The charge and discharge circuit according to claim 1, characterized in that: When the charging and discharging circuit is located at the charging end, when the charging end charges the receiving end, the common mode voltage detected by the voltage detection circuit is greater than the voltage reference value.

6. The charge and discharge circuit according to claim 2, characterized in that: The common-mode compensation circuit is integrated inside the controller of the charge-discharge circuit.

7. An electronic device, characterized in that: It comprises the charging and discharging circuit according to any one of claims 1 to 6; the electronic device is a charging end or a power receiving end.

8. The electronic device according to claim 7, characterized in that: The electronic device is a charger or a display.

9. A communication system, characterized in that: The electronic device according to claim 7 or 8, further comprising a peer device; When the electronic device is a charging terminal, it is used to charge the opposite device; When the electronic device is a power receiving end, it is used to be charged by the opposite end device.

10. A common mode voltage regulation method, characterized in that: include: When the charging and discharging circuit establishes communication with the charging terminal, sampling the common mode voltage of the configuration channel of the charging and discharging circuit; According to the comparison result between the common mode voltage and the voltage reference value, the transmission signal of the transmitter is adjusted, and the adjusted transmission signal is output to the configuration channel.

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