Solar charging circuit and chip

Abstract

The embodiment of the invention discloses a solar charging circuit and a chip, and the circuit comprises a first switching tube which is connected between a receiving end and a battery voltage end, the receiving end is used for receiving the output voltage of a solar panel, and the battery voltage end is used for being connected with a battery; the first detection module is used for acquiring a first electric signal representing the voltage magnitude of the battery voltage end; the second detection module is used for acquiring a second electric signal representing the voltage of the receiving end; and the current control module is respectively connected with the first switch tube, the first detection module and the second detection module, and controls the charging current flowing to the battery voltage end through the first switch tube based on the first electric signal and the second electric signal. Through the implementation of the invention, the battery can be still charged under the condition of insufficient light intensity, the influence of triggering of an abnormal protection circuit in the circuit and the condition of charging-charging stopping-charging circulation are avoided, the charging efficiency is effectively improved, and the energy waste is also avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of integrated circuits, and in particular to a solar charging circuit and a chip. BACKGROUND

[0002] At present, the solar charging technology has been widely applied in the energy storage technology field due to its advantages of being clean and pollution-free. A conventional solar charging circuit usually includes a solar panel, an energy storage unit and a power management circuit. In the existing solar charging circuit, a starting threshold based on voltage comparison is usually set. When the output voltage of the solar panel is higher than a preset value, the circuit is activated to start working. When the output voltage is lower than the threshold, the charging process is stopped to prevent invalid energy loss or abnormal charging of the battery. However, it is found in actual application that in a weak light environment, the output power of the solar panel is already greatly reduced, and its output voltage is prone to fluctuate around the starting threshold. This will cause the charging circuit to frequently start and stop. The circuit itself needs to consume energy during the starting process. Frequent start and stop makes most of the scarce energy consumed in the initialization process of the circuit itself, which cannot be effectively used for battery charging, greatly shortens the actual effective charging time, and the overall energy collection efficiency is very low. At the same time, the threshold-based judgment method cannot effectively utilize the weak energy continuously output by the solar panel, resulting in serious energy waste. In summary, the solar charging technology in the prior art has the problems of low charging efficiency and serious energy waste. SUMMARY

[0003] The purpose of the embodiment of the present application is to provide a solar charging circuit and a chip to solve the above problems. The embodiment of the present application achieves the above purpose through the following technical scheme.

[0004] The embodiment of the present application provides a solar charging circuit, which comprises: a first switch tube connected between a receiving end and a battery voltage end, the receiving end being used for receiving an output voltage of a solar panel, and the battery voltage end being used for being connected with a battery; a first detection module for acquiring a first electric signal representing the voltage size of the battery voltage end; a second detection module for acquiring a second electric signal representing the voltage size of the receiving end; and a current control module connected with the first switch tube, the first detection module and the second detection module respectively, and used for controlling the charging current size flowing to the battery voltage end through the first switch tube based on the first electric signal and the second electric signal.

[0005] In some embodiments, the current control module comprises: a current unit connected with the first switch tube and providing the first switch tube with a first current; a first current compensation unit, when the voltage value of the battery voltage terminal corresponding to the first electric signal is greater than a first preset value, providing the current unit with a first compensation current to reduce the first current; and a second current compensation unit, when the voltage value of the receiving terminal corresponding to the second electric signal is less than a second preset value, providing the current unit with a second compensation current to reduce the first current.

[0006] In some embodiments, the second preset value follows the voltage variation of the battery voltage terminal.

[0007] In some embodiments, the first electric signal comprises a signal with a first coefficient of the voltage of the battery voltage terminal, and the second electric signal comprises a signal with a second coefficient of the voltage of the receiving terminal, and the first coefficient is greater than the second coefficient.

[0008] In some embodiments, the current unit and the first switch tube constitute a mirror circuit to provide the first switch tube with the first current, and the first current is a constant current.

[0009] In some embodiments, the current unit comprises a second switch tube, a third switch tube, a first operational amplifier, a first energy consumption element and a second energy consumption element.

[0010] The first end of the second switch tube, the first end of the first switch tube and the voltage terminal are connected, the second end of the second switch tube and the second end of the third switch tube are connected, the first input end of the second operational amplifier and the first current compensation unit, the second current compensation unit and the first end of the first energy consumption element are connected, the second input end of the first operational amplifier and the first preset voltage terminal are connected, the output end of the first operational amplifier and the third end of the first switch tube and the third end of the second switch tube are connected, the first end of the third switch tube and the second end of the first energy consumption element and the first end of the second energy consumption element are connected, and the second end of the second energy consumption element and the reference ground terminal are connected.

[0011] In some embodiments, the flow direction of the first compensation current is from the first end of the first energy consumption element to the second end of the first energy consumption element, and the flow direction of the second compensation current is from the first end of the first energy consumption element to the second end of the first energy consumption element.

[0012] In some embodiments, the current unit further comprises a second operational amplifier, the first input end of the second operational amplifier and the second end of the second switch tube are connected, the second input end of the second operational amplifier and the second end of the second switch tube are connected, and the output end of the second operational amplifier and the third end of the third switch tube are connected.

[0013] In some embodiments, the first energy consumption element comprises a first resistor and a second resistor connected in series, the first resistor is connected to the first input terminal of the first operational amplifier, and the second resistor is connected to the first terminal of the third switch tube, the first resistor is greater than the second resistor, and the voltage of the common connection point formed by the first resistor and the second resistor is detected to determine the time of stopping charging the battery.

[0014] The embodiment of the present application also provides a solar charging chip comprising the solar charging circuit according to any one of the above embodiments.

[0015] Compared with the prior art, by adopting the solar charging circuit comprising the first switch tube, the first detection module, the second detection module and the current control module, the charging current size is adjusted based on the acquired electric signal, the voltage size of the receiving end is effectively limited, the battery can still be charged in the case of insufficient light intensity, the charging-stop charging-charging cycle situation caused by the abnormal protection circuit in the circuit is avoided, the charging efficiency is effectively improved, and energy waste is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the description of the embodiments of the present application will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0017] Figure 1 is a module schematic diagram of the solar charging circuit provided by the embodiment of the present application;

[0018] Figure 2 is another module schematic diagram of the solar charging circuit provided by the embodiment of the present application;

[0019] Figure 3 is a circuit structure schematic diagram of the solar charging circuit provided by the embodiment of the present application. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0021] The "coupling" or "connection" in the present application includes both direct connection and indirect connection, such as connection through some active devices, passive devices or electrically conductive media; it can also include connection through other active devices or passive devices known to those skilled in the art on the basis of achieving the same or similar functional purposes, such as connection through switches, follower circuits or other circuits or components.

[0022] The inventor of the present application found that, due to the influence of the power of the solar panel on the light intensity, there is a power shortage, and if the charging controller charges the battery in a constant current manner at this time, the output voltage of the solar panel will be pulled down to slightly higher than the battery voltage, causing the charging controller to misjudge and trigger abnormal protection, closing the charging path. After the charging path is closed, the output voltage of the solar panel recovers, and the charging controller will charge the battery again, resulting in a charging-stop charging-charging cycle process, which affects the charging efficiency of the battery. That is, the existing solar charging scheme will be affected by the triggering of the abnormal protection circuit in the charging control in actual application, resulting in a charging-stop charging-charging cycle process. Therefore, the inventor of the present application considers the above problems and the defects of the voltage preset value scheme described in the background art, and proposes the solar charging circuit and chip provided in the embodiments of the present application.

[0023] As shown in Figure 1 The solar charging circuit provided by the present embodiment includes: a first switch tube M1 connected between a receiving end SOL and a battery voltage end BAT, the receiving end SOL being used for receiving the output voltage of a solar panel, and the battery voltage end BAT being used for connecting with a battery B; a first detection module 11 acquiring a first electric signal representing the voltage of the battery voltage end BAT; a second detection module 12 acquiring a second electric signal representing the voltage of the receiving end SOL; and a current control module 13 connected with the first switch tube M1, the first detection module 11 and the second detection module 12 respectively, and controlling the charging current flowing to the battery voltage end BAT through the first switch tube M1 based on the first electric signal and the second electric signal.

[0024] In the present embodiment, the solar panel can absorb light intensity and convert light energy into electric energy, and the electric energy output by the solar panel is transmitted to the battery B through the receiving end SOL, the first switch tube M1 and the battery voltage end BAT to charge the battery B. The solar panel can be a single crystal silicon solar panel, a polycrystalline silicon solar panel, a thin film solar panel, a perovskite solar panel, a dye-sensitized solar panel, an organic solar panel, etc. The specific type of the solar panel is not limited here.

[0025] In the embodiment, the first electrical signal can include voltage and current, and the first detection module 11 can obtain the first electrical signal by voltage division detection or direct detection. When the voltage of the battery voltage terminal BAT changes, the first electrical signal also changes accordingly. Similarly, the second electrical signal can include voltage and current, and the second detection module 12 can obtain the second electrical signal by voltage division detection or direct detection. When the voltage of the receiving terminal SOL changes, the second electrical signal also changes accordingly.

[0026] In the embodiment, the current control module 13 can control the charging current flowing through the first switch tube M1 to the battery voltage terminal BAT. Specifically, when it is determined based on the first electrical signal that the voltage of the battery voltage terminal BAT rises to the first threshold value, the battery charging mode can be switched from the constant current charging mode to the constant voltage charging mode. When the battery charging mode is switched from the constant current charging mode to the constant voltage charging mode, the charging current can be controlled to decrease.

[0027] In the embodiment, when it is determined based on the second electrical signal that the voltage of the receiving terminal SOL decreases to the second threshold value, the charging current can be controlled to decrease. The current control module 13 controls the charging current flowing through the first switch tube M1 to the battery voltage terminal BAT based on the first electrical signal and controls the charging current flowing through the first switch tube M1 to the battery voltage terminal BAT based on the first electrical signal, which are independent of each other. When the first electrical signal and the second electrical signal both satisfy the corresponding conditions, the current control module 13 can adjust the charging current according to the pre-set charging strategy.

[0028] In the embodiment, when the battery charging mode is the constant current charging mode, and the voltage of the battery voltage terminal BAT is detected to not rise to the first threshold value and the voltage of the receiving terminal SOL is detected to drop to the second threshold value, it indicates that the solar power is insufficient at this time, and the charging current can be controlled to drop. The greater the drop of the voltage of the receiving terminal SOL, the greater the drop of the charging current, so as to avoid that the output voltage of the solar panel is pulled down too low, and the battery B can still be charged in the case that the light intensity is weak. When the battery charging mode is the constant current charging mode, and the voltage of the battery voltage terminal BAT is detected to rise to the first threshold value and the voltage of the receiving terminal SOL is detected to not drop to the second threshold value, it indicates that the solar power is sufficient at this time, and the battery charging mode can be switched from the constant current charging mode to the constant voltage charging mode, and the charging current gradually decreases. When the battery charging mode is the constant voltage charging mode, and the voltage of the battery voltage terminal BAT is detected to be greater than the first threshold value and the voltage of the receiving terminal SOL is detected to drop to the second threshold value, it indicates that the solar power is insufficient at this time, and the battery charging mode is the constant voltage charging mode, and the charging current is further reduced on the basis of gradually decreasing.

[0029] In the embodiment, by adopting the solar charging circuit including the first switch tube M1, the first detection module 11, the second detection module 12 and the current control module 13, the charging current size is adjusted based on the obtained electrical signals, the voltage of the receiving terminal SOL is effectively limited, the battery B can still be charged in the case that the light intensity is insufficient, the charging-stop-charging cycle situation is avoided, the charging efficiency is effectively improved, and energy waste is avoided.

[0030] In some embodiments, as shown in Figure 2 The current control module 13 can include: a current unit 133 connected with the first switch tube M1 and providing the first switch tube M1 with a first current; a first current compensation unit 131 configured to provide the constant current unit with a first compensation current when the voltage value of the battery voltage terminal BAT corresponding to the first electrical signal is greater than a first preset value, so as to reduce the first current; and a second current compensation unit 132 configured to provide the constant current unit with a second compensation current when the voltage value of the receiving terminal SOL corresponding to the second electrical signal is less than a second preset value, so as to reduce the first current.

[0031] In the embodiment, the first preset value and / or the second preset value can be a fixed value or a variable value based on the change of the electrical signal in the circuit.

[0032] In the embodiment, at a certain moment, the first compensation current and the second compensation current can exist at the same time, and one of them exists. The greater the first compensation current, the smaller the first current. The greater the second compensation current, the smaller the first current.

[0033] In some embodiments, after the voltage value of the battery voltage terminal BAT corresponding to the first electrical signal is greater than the first preset value, the voltage value of the battery voltage terminal BAT corresponding to the first electrical signal can continue to rise, the greater the voltage value of the battery voltage terminal BAT corresponding to the first electrical signal, the greater the first compensation current provided by the first current compensation unit 131. After the voltage value of the receiving terminal SOL corresponding to the second electrical signal is less than the second preset value, the voltage value of the receiving terminal SOL corresponding to the second electrical signal can continue to decrease, the smaller the voltage value of the receiving terminal SOL corresponding to the second electrical signal, the greater the second compensation current provided by the second current compensation unit 132.

[0034] In some embodiments, the second preset value can follow the voltage change of the battery voltage terminal BAT. Specifically, the second preset value can be a certain coefficient of the voltage of the battery voltage terminal BAT, the more the battery charge, the greater the voltage of the battery voltage terminal BAT, and when the voltage of the battery voltage terminal BAT is relatively large, the corresponding second preset value is also relatively high. Thus, the second compensation current can be set based on the battery B charge amount in the case of weak light intensity, ensuring that the voltage of the receiving terminal SOL is always greater than the voltage of the battery voltage terminal BAT when the light intensity is weak, and the voltage of the receiving terminal SOL and the voltage of the battery voltage terminal BAT maintain a certain difference, always maintaining the state of the solar panel charging the battery B, and realizing the battery B charging in the case of the battery charge not being full.

[0035] In some embodiments, the first electrical signal can include a signal having a first coefficient with the voltage of the battery voltage terminal BAT, and the second electrical signal can include a signal having a second coefficient with the voltage of the receiving terminal SOL, and the first coefficient is greater than the second coefficient.

[0036] In the present embodiment, the first electrical signal and the second electrical signal can be obtained by means of voltage division sampling.

[0037] In some embodiments, the current unit 133 and the first switch tube M1 constitute a mirror circuit to provide the first switch tube M1 with a first current, and the first current is a constant current.

[0038] In the present embodiment, the current unit 133 can be regarded as an input circuit of the mirror circuit, and the first switch tube M1 can be regarded as an output circuit of the mirror circuit, when the current provided by the input circuit is in a constant state, the first current will also be in a constant state.

[0039] In some embodiments, as Figure 3As shown, the current unit 133 can include a second switch tube M2, a third switch tube M3, a first operational amplifier A1, a first energy consumption element, and a second energy consumption element; wherein the first end of the second switch tube M2, the first end of the first switch tube M1, and the voltage end are connected, the second end of the second switch tube M2 and the second end of the third switch tube M3 are connected, the first input end of the second operational amplifier A2 is connected with the first current compensation unit 131, the second current compensation unit 132, and the first end of the first energy consumption element, the second input end of the first operational amplifier A1 is connected with the first preset voltage end, the output end of the first operational amplifier A1 is connected with the third end of the first switch tube M1 and the third end of the second switch tube M2, the first end of the third switch tube M3 is connected with the second end of the first energy consumption element and the first end of the second energy consumption element, and the second end of the second energy consumption element is connected with the reference ground end.

[0040] In the embodiment, as shown in Figure 3 When the first switch tube M1 is a PMOS transistor, the second switch tube M2 is a PMOS transistor, and the third switch tube M3 is an NMOS transistor, the first end of the first switch tube M1, the first end of the second switch tube M2, and the first end of the third switch tube M3 can be the source, the second end of the first switch tube M1, the second end of the second switch tube M2, and the second end of the third switch tube M3 can be the drain, and the third end of the first switch tube M1, the third end of the second switch tube M2, and the third end of the third switch tube M3 can be the gate. It should be noted that the first switch tube M1, the second switch tube M2, and the third switch tube M3 can also be bipolar junction transistors, insulated gate bipolar transistors, etc., as long as the functions required by the switch tubes in the embodiment can be realized.

[0041] In the embodiment, as shown in Figure 3 The first energy consumption element and the second energy consumption element can be resistors. Specifically, the first energy consumption element and the second energy consumption element can include a plurality of resistors which can be combined in series and parallel.

[0042] In the embodiment, the first switch tube M1 and the second switch tube M2 can constitute a mirror circuit, the current flowing through the first switch tube M1 and the current flowing through the second switch tube M2 have a preset ratio, the current flowing through the second switch tube M2 and the current flowing through the second energy consumption element are basically the same, and the voltage at the first end of the second energy consumption element and the first voltage end is basically the same. The voltage at the first voltage end can be controlled to control the current flowing through the second energy consumption element, and then control the charging current size to the battery B.

[0043] In some embodiments, as shown in Figure 3As shown, the current unit 133 can further include a second operational amplifier A2, a first input end of the second operational amplifier A2 is connected with the second end of the second switch tube M2, a second input end of the second operational amplifier A2 is connected with the second end of the second switch tube M2, and an output end of the second operational amplifier A2 is connected with the third end of the third switch tube M3.

[0044] In the embodiment, through the cooperation of the second operational amplifier A2 and the third switch tube M3, the voltage at the second end of the first switch tube M1 can be made substantially consistent with the voltage at the second end of the second switch tube M2, so that the current output by the second end of the first switch tube M1 is more close to the expectation.

[0045] In some embodiments, the flow direction of the first compensation current is from the first end of the first energy consumption element to the second end of the first energy consumption element; and the flow direction of the second compensation current is from the first end of the first energy consumption element to the second end of the first energy consumption element.

[0046] In the embodiment, when the first current compensation unit 131 starts to provide the first compensation current, the greater the voltage at the battery voltage end BAT, the greater the first compensation current, and the smaller the charging current. When the second current compensation unit 132 starts to provide the second compensation current, the smaller the voltage at the receiving end SOL, the greater the second compensation current, and the smaller the charging current; or, when the second current compensation unit 132 starts to provide the second compensation current, the smaller the difference between the voltage at the receiving end SOL and the voltage at the battery voltage end BAT, the greater the second compensation current, and the smaller the charging current.

[0047] As shown in the figure, Figure 3 The first current compensation unit 131 can include a third operational amplifier A3, a first input end of the third operational amplifier A3 is connected with the second voltage end, a second input end of the third operational amplifier A3 receives the first electric signal of the first detection module 11, and an output end of the third operational amplifier A3 is connected with the first input end of the first operational amplifier A1 and the first end of the first energy consumption element. The third operational amplifier A3 can convert the voltage difference between the second voltage end and the first electric signal into the first compensation current.

[0048] In the embodiment, when the voltage represented by the first electric signal is greater than the voltage at the second voltage end, the third operational amplifier A3 generates the first compensation current based on the voltage difference between the second voltage end and the first electric signal, and the first compensation current flows from the first end of the first energy consumption element to the second energy consumption element, so that the voltage at the common connection point formed by the second end of the first energy consumption element and one end of the second energy consumption element decreases, the current flowing through the second energy consumption element decreases, and further causes the charging current flowing through the first switch tube M1 to decrease.

[0049] As shown in the figure, Figure 3As shown, the second current compensation unit 132 can include a fourth operational amplifier A4, a first input end of the fourth operational amplifier A4 receiving the second electric signal of the second detection module 12, a second input end of the fourth operational amplifier A4 receiving a third electric signal for representing the voltage of the battery voltage terminal BAT, and an output end of the fourth operational amplifier A4 being connected with the first input end of the first operational amplifier A1 and the first end of the first energy consumption element. The third operational amplifier A3 can convert the voltage difference between the voltage represented by the second electric signal and the voltage represented by the first electric signal into the second compensation current. Alternatively, the second current compensation unit 132 can include a fourth operational amplifier A4, a first input end of the fourth operational amplifier A4 receiving the second electric signal of the second detection module 12, a second input end of the fourth operational amplifier A4 being connected with the third voltage terminal, and an output end of the fourth operational amplifier A4 being connected with the first input end of the first operational amplifier A1 and the first end of the first energy consumption element. The third operational amplifier A3 can convert the voltage difference between the voltage represented by the second electric signal and the voltage represented by the third electric signal into the second compensation current, wherein the third voltage terminal provides a fixed voltage.

[0050] In the present embodiment, when the voltage represented by the second electric signal is greater than the voltage represented by the third electric signal, the fourth operational amplifier A4 converts and generates the second compensation current based on the voltage difference between the voltage represented by the second electric signal and the voltage represented by the third electric signal; or when the voltage represented by the second electric signal is greater than the voltage of the third voltage terminal, the fourth operational amplifier A4 converts and generates the second compensation current based on the voltage difference between the voltage represented by the second electric signal and the voltage of the third voltage terminal. The second compensation current flows to the second energy consumption element through the first end of the first energy consumption element, so that the voltage at the common junction formed by the second end of the first energy consumption element and one end of the second energy consumption element decreases, the current flowing through the second energy consumption element decreases, and further causes the charging current flowing through the first switch tube M1 to decrease.

[0051] In some embodiments, the first energy consumption element includes a first resistor R1 and a second resistor R2 connected in series, the first resistor R1 being connected with the first input end of the first operational amplifier A1, and the second resistor R2 being connected with the first end of the third switch tube M3. The first resistor R1 is greater than the second resistor R2, and the time for stopping charging the battery B is determined by detecting the voltage at the common junction formed by the first resistor R1 and the second resistor R2.

[0052] In the embodiment, the more the battery power is, the smaller the charging current will be, and the smaller the current synchronously flowing through the second energy consumption element is, and the voltage difference between the first end and the second end of the first energy consumption element is larger, at this time, the first resistor R1 is set to be larger than the second resistor R2, and the voltage of the common connection point formed by the first resistor R1 and the second resistor R2 will be reduced, when the voltage of the common connection point is smaller than the voltage of the fourth voltage terminal, it means that the battery power is about to be full, and there is no need to specially set other circuits to detect the power. Wherein, the first resistor R1 can be much larger than the second resistor R2.

[0053] Specifically, the comparator A5 can be set, the first input terminal of the comparator A5 is connected with the common connection point formed by the first resistor R1 and the second resistor R2, the second input terminal of the comparator A5 is connected with the fourth voltage terminal, and the output terminal of the comparator A5 is used to control the battery B charging process, when the signal output by the output terminal of the comparator A5 represents that the battery power is full, the charging of the battery B can be controlled to stop.

[0054] As shown in Figure 3 The second energy consumption element can be the third resistor R3.

[0055] The embodiment of the present application further provides a solar charging chip, which comprises the solar charging circuit provided by any one of the above embodiments.

[0056] Since the circuit structure and working mode of the solar charging circuit in the solar charging chip in the embodiment are the same as those of the solar charging circuit in the above embodiments, no further description is given here.

[0057] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit the same; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can still be modified, or some technical features can be replaced by equivalent ones; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A solar charging circuit, characterized by, include: The first switching transistor is connected between the receiving end and the battery voltage end. The receiving end is used to receive the output voltage of the solar panel, and the battery voltage end is used to connect to the battery. The first detection module acquires a first electrical signal that characterizes the voltage magnitude at the battery voltage terminal; The second detection module acquires a second electrical signal that characterizes the voltage magnitude of the receiving end; The current control module is connected to the first switch, the first detection module, and the second detection module respectively, and controls the magnitude of the charging current flowing to the battery voltage terminal through the first switch based on the first electrical signal and the second electrical signal.

2. The solar charging circuit of claim 1, wherein, The current control module includes: A current unit is connected to the first switching transistor and provides a first current to the first switching transistor. When the voltage value at the battery voltage terminal corresponding to the first electrical signal is greater than a first preset value, the first current compensation unit provides a first compensation current to the constant current unit to reduce the first current. When the voltage value at the receiving end corresponding to the second electrical signal is less than a second preset value, the second current compensation unit provides a second compensation current to the constant current unit to reduce the first current.

3. The solar charging circuit of claim 1, wherein, The second preset value changes according to the voltage at the battery voltage terminal.

4. The solar charging circuit of claim 2, wherein, The first electrical signal includes a signal having a first coefficient with respect to the voltage at the battery voltage terminal, and the second electrical signal includes a signal having a second coefficient with respect to the voltage at the receiving terminal, wherein the first coefficient is greater than the second coefficient.

5. The solar charging circuit of claim 2, wherein, The current unit and the first switching transistor form a mirror circuit to provide the first current to the first switching transistor, and the first current is a constant current.

6. The solar charging circuit of claim 2, wherein, The current unit includes a second switching transistor, a third switching transistor, a first operational amplifier, a first energy-consuming element, and a second energy-consuming element; Wherein, the first end of the second switching transistor and the first end of the first switching transistor are connected to the voltage terminal, the second end of the second switching transistor is connected to the second end of the third switching transistor, the first input terminal of the second operational amplifier is connected to the first current compensation unit, the second current compensation unit, and the first end of the first energy-consuming element, the second input terminal of the first operational amplifier is connected to the first preset voltage terminal, the output terminal of the first operational amplifier is connected to the third end of the first switching transistor and the third end of the second switching transistor, the first end of the third switching transistor is connected to the second end of the first energy-consuming element and the first end of the second energy-consuming element, and the second end of the second energy-consuming element is connected to the reference ground terminal.

7. The solar charging circuit of claim 6, wherein, The direction of the first compensation current is from the first end of the first energy-consuming element to the second end of the first energy-consuming element; the direction of the second compensation current is from the first end of the first energy-consuming element to the second end of the first energy-consuming element.

8. The solar charging circuit of claim 6, wherein, The current unit further includes a second operational amplifier, the first input terminal of the second operational amplifier is connected to the second terminal of the second switching transistor, the second input terminal of the second operational amplifier is connected to the second terminal of the second switching transistor, and the output terminal of the second operational amplifier is connected to the third terminal of the third switching transistor.

9. The solar charging circuit of claim 6, wherein, The first energy consumption element comprises a first resistor and a second resistor connected in series, the first resistor is connected with the first input end of the first operational amplifier, the second resistor is connected with the first end of the third switch tube, the first resistor is greater than the second resistor, and the voltage of the common junction point formed by the first resistor and the second resistor is detected to determine the time of stopping charging the battery.

10. A solar charging chip, characterized by, A solar charging circuit comprising the solar charging circuit according to any one of claims 1 to 9.

Images