Charging circuit and integrated circuit thereof

Abstract

According to an embodiment of the present invention, a charging circuit and an integrated circuit thereof are disclosed. The charging circuit of the present invention comprises a first input terminal, a first switch circuit, a second switch circuit and a bidirectional buck-boost circuit. The first input terminal receives an input signal, the first switch circuit is coupled between the first input terminal and a first battery, the second switch circuit is coupled between the first input terminal and the second battery, and the bidirectional buck-boost circuit is coupled between the first input terminal and a main battery. When an external power source is connected, the input signal charges the first battery and the second battery respectively through the first switch circuit and the second switch circuit, and charges the main battery through the bidirectional buck-boost circuit. When no external power source is connected, the main battery charges the first battery through the bidirectional buck-boost circuit and the first switch circuit, and charges the second battery through the bidirectional buck-boost circuit and the second switch circuit. The charging circuit of the present invention has a small size, low cost, and high charging efficiency and charging rate.

Description

Technical Field

[0001] The present invention relates to the field of power electronics, and more particularly to a charging circuit and an integrated circuit thereof. Background Art

[0002] As consumers have higher requirements for earphone functions, the types of earphones are updated day by day, and new earphones are introduced and used, especially the widespread use of TWS (True wireless stereo) earphones, which puts higher requirements on the charging circuit of earphones. Figure 1 As shown, the charging circuit includes a buck circuit 1, a boost circuit 2 and a linear charging module 3. When the charging circuit is connected to an external power source, the buck circuit 1 receives an input voltage Vin output by a wired power source or a wireless power source, and the input voltage Vin charges the main battery Bm of the earphone through the buck circuit 1. At the same time, the input voltage Vin charges the first battery B1 and the second battery B2 through the buck circuit 1, the boost circuit 2 and the linear charging module 3 in sequence. When the charging circuit is not connected to an external power source, the main battery Bm charges the first battery B1 and the second battery B2 through the boost circuit 2 and the linear charging module 3 in sequence. The first battery B1 and the second battery B2 are respectively located in the left and right earplugs, so that the linear charging module 3 includes a first linear charging module 31 and a second linear charging module 32 respectively located in the left and right earphones, and the voltage output by the boost circuit 2 is respectively passed through the first linear charging module 31 and the second linear charging module 32 to charge the first battery B1 and the second battery B2.

[0003] In the prior art, the switch circuit 11 of the buck circuit 1 is integrated in the first chip, the switch circuit 21 of the boost circuit 2 is integrated in the second chip, the first linear charging module 31 is integrated in the third chip, and the second linear charging module 32 is integrated in the fourth chip, that is, the charging circuit requires 4 chips and includes two inductors L1 and L2, so the charging circuit in the prior art is large in size and high in cost. In addition, the charging efficiency and charging rate of the charging circuit are low. Summary of the invention

[0004] In view of this, the present invention proposes a charging circuit and an integrated circuit thereof with a small size, high charging efficiency and charging rate, so as to solve the technical problems of the charging circuit being large in size and low in charging efficiency and charging rate in the prior art.

[0005] In a first aspect, an embodiment of the present invention provides a charging circuit, comprising: a first input terminal for receiving an input signal; a first switch circuit coupled between the first input terminal and a first battery; a second switch circuit coupled between the first input terminal and the second battery; a bidirectional buck-boost circuit coupled between the first input terminal and a main battery; when an external power source is connected, the input signal charges the first battery and the second battery respectively through the first switch circuit and the second switch circuit, and charges the main battery through the bidirectional buck-boost circuit; when no external power source is connected, the main battery charges the first battery through the bidirectional buck-boost circuit and the first switch circuit, and charges the second battery through the bidirectional buck-boost circuit and the second switch circuit.

[0006] Preferably, when the main battery is charged, the bidirectional buck-boost circuit works in a forward direction; when the main battery is discharged, the bidirectional buck-boost circuit works in a reverse direction.

[0007] Preferably, when no external power source is connected, the main battery charges the first battery and the second battery in a time-sharing manner through the bidirectional buck-boost circuit.

[0008] Preferably, when no external power source is connected, the main battery charges the first battery in one switching cycle and charges the second battery in the next switching cycle through the bidirectional buck-boost circuit.

[0009] Preferably, the bidirectional buck-boost circuit includes an inductor. When no external power supply is connected, during a part of a switching cycle, the main battery charges the inductor, and during another part of a switching cycle, the first switching circuit works in an on state, and the inductor charges the first battery; during a part of the next switching cycle, the main battery charges the inductor, and during another part of the next switching cycle, the second switching circuit works in an on state, and the inductor charges the second battery.

[0010] Preferably, when no external power supply is connected, the second end of the bidirectional buck-boost circuit receives the voltage of the main battery, and generates a first voltage and a first current at its first end to charge the first battery and the second battery; the first battery and / or the second battery are first charged with a constant current for fast charging; when the voltage of the first battery and / or the second battery reaches the corresponding reference voltage, the first battery and the second battery are charged with a constant voltage.

[0011] Preferably, when the first current is controlled to be constant and the first voltage is controlled to increase gradually, the first battery and / or the second battery are charged with a constant current; when the first voltage is controlled to be constant, the first battery and the second battery are charged with a constant voltage.

[0012] Preferably, when the first battery and / or the second battery is subjected to constant current charging, the first voltage is controlled to increase as the voltage of the first battery or the second battery increases.

[0013] Preferably, when an external power source is connected, the first battery and / or the second battery are first charged with a constant current for fast charging; when the voltage of the first battery and / or the second battery reaches a corresponding reference voltage, the first battery and the second battery are charged with a constant voltage.

[0014] Preferably, the input signal includes an input voltage and an input current. When the input current is constant and the input voltage gradually increases, the first battery and / or the second battery are charged with a constant current; when the input voltage is constant, the first battery and the second battery are charged with a constant voltage.

[0015] Preferably, when the first battery and / or the second battery is charged with a constant current, the input voltage increases as the voltage of the first battery or the second battery increases.

[0016] Preferably, when the input current or the first current is constant and the input voltage or the first voltage increases gradually, the first battery and the second battery are charged with a constant current, and the first switch circuit and the second switch circuit operate in an on state.

[0017] Preferably, when the input current or the first current is constant and the input voltage or the first voltage gradually increases, the first battery and the second battery are charged with a constant current, the switch circuit corresponding to the battery with a higher voltage between the first battery and the second battery operates in an on state, and the switch circuit corresponding to the battery with a lower voltage between the first battery and the second battery operates in a linear state, or first operates in a linear state and then operates in an on state.

[0018] Preferably, when the input current or the first current is constant and the input voltage or the first voltage gradually increases, the battery with a lower voltage among the first battery and the second battery is charged with a constant current, and the switch circuit corresponding to the battery with a lower voltage among the first battery and the second battery operates in an on state, and the switch circuit corresponding to the battery with a higher voltage among the first battery and the second battery does not work first and then works in a linear state, or does not work first and then works in an on state, or does not work first and then works in a linear state, and finally works in an on state.

[0019] Preferably, when the input current or the first current is constant and the input voltage or the first voltage gradually increases, the battery with the lower voltage between the first battery and the second battery is charged with a constant current, the switch circuit corresponding to the battery with the lower voltage between the first battery and the second battery operates in an on state, and the switch circuit corresponding to the battery with the higher voltage between the first battery and the second battery first operates in a linear state, or first operates in a linear state and then operates in an on state.

[0020] Preferably, when the input voltage or the first voltage is constant, the first battery and the second battery are charged at a constant voltage, and the first switch circuit and the second switch circuit operate in a linear state.

[0021] Preferably, when an external power source is connected, the first switch circuit and the second switch circuit operate in a linear state to charge the first battery and the second battery respectively.

[0022] Preferably, the voltage of the first battery and the current flowing through the first switch circuit are adjusted by controlling the voltage of the control terminal of the first switch circuit to control the resistance value of the first switch circuit; and the voltage of the second battery and the current flowing through the second switch circuit are adjusted by controlling the voltage of the control terminal of the second switch circuit to control the resistance value of the second switch circuit.

[0023] Preferably, the first switch circuit is a first switch tube, and the second switch circuit is a second switch tube.

[0024] Preferably, the charging circuit further comprises a second input terminal, wherein the first input terminal is used to receive an input signal output by a wired power source, and the second input terminal is used to receive an input signal output by a wireless power source.

[0025] Preferably, the first input terminal and the second input terminal are respectively coupled to a switch tube for preventing the first input terminal and the second input terminal from outputting a signal.

[0026] Preferably, a third switch tube is coupled between the second end of the bidirectional buck-boost circuit and the main battery, and when the voltage of the main battery is greater than a first threshold voltage, the third switch tube is turned off.

[0027] In a second aspect, an embodiment of the present invention further provides an integrated circuit, based on any of the above charging circuits, comprising: the first switch circuit, the second switch circuit and the switch tube in the bidirectional buck-boost circuit are integrated in the same integrated circuit.

[0028] Preferably, the integrated circuit comprises a first input port for receiving an input signal output by a wired power source or an input signal output by a wireless power source.

[0029] Preferably, the integrated circuit comprises a first input port and a second input port, the first input port is used to receive an input signal output by a wired power supply, and the second input port is used to receive an input signal output by a wireless power supply.

[0030] Preferably, the integrated circuit comprises a first output port, a second output port and a third output port for respectively coupling to the first battery, the second battery and the main battery.

[0031] Compared with the prior art, the technical solution of the present invention has the following advantages: the charging circuit of the present invention comprises a first input terminal, a first switch circuit, a second switch circuit and a bidirectional buck-boost circuit, the first input terminal is used to receive an input signal, the first switch circuit is coupled between the first input terminal and the first battery, the second switch circuit is coupled between the first input terminal and the second battery, and the bidirectional buck-boost circuit is coupled between the first input terminal and the main battery; when an external power supply is connected, the input signal charges the first battery and the second battery respectively through the first switch circuit and the second switch circuit, and charges the main battery through the bidirectional buck-boost circuit; when no external power supply is connected, the main battery charges the first battery through the bidirectional buck-boost circuit and the first switch circuit, and charges the second battery through the bidirectional buck-boost circuit and the second switch circuit. The charging circuit of the present invention only requires one chip and only one inductor to complete the charging of the first battery and the second battery, so that the charging circuit is small in size and low in cost. And the charging efficiency and charging rate of the charging circuit are high. The charging circuit of the present invention has a SIMO (single-inductor, multiple-output) structure, and only one integrated circuit (chip) is needed to complete the functions that the prior art requires four chips to complete, and only one inductor is needed, which reduces the volume and cost of the circuit. In addition, the charging circuit of the present invention improves the charging efficiency and charging rate of each charging process (including the charging process of the first battery and the second battery when the external power supply is connected, the charging process of the main battery when the external power supply is connected, and the charging process of the main battery to the first battery and the second battery), further optimizes the heat dissipation of the system, prolongs the life of the main battery, and reduces the cost. Since the main battery in the present invention has better efficiency in charging the first battery and the second battery than the prior art, the service life of the main battery is extended. When the main battery capacity is the same, after the main battery is fully charged, the main battery of the charging circuit of the present invention can charge the first battery and the second battery in more charging cycles. In addition, the charging circuit of the present invention has two independent outputs, which can charge two independent batteries. When the charging circuit of the present invention charges the earphone (such as a TWS earphone), the first battery and the second battery are respectively located in the left and right earplugs of the earphone, and the main battery is located in the battery box. Furthermore, the charging circuit of the present invention can be used not only in headphones but also in other devices. The charging circuit of the present invention is used to charge independent dual batteries, where the first battery and the second battery can be in two different terminals (such as the left and right ears of the headphones), or they can be opposite-sex batteries in the same terminal, that is, the capacity of the first battery and the second battery is quite different. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0033] Figure 1 A schematic diagram of a prior art charging circuit;

[0034] Figure 2 This is a circuit diagram of a first embodiment of a charging circuit of the present invention;

[0035] Figure 3 This is a circuit diagram of a second embodiment of a charging circuit of the present invention. DETAILED DESCRIPTION

[0036] The present invention is described below based on embodiments, but the present invention is not limited to these embodiments. In the detailed description of the present invention below, some specific details are described in detail. It is possible for a person skilled in the art to fully understand the present invention without the description of these details. In order to avoid confusing the essence of the present invention, known methods, processes, flows, components and circuits are not described in detail.

[0037] In addition, persons of ordinary skill in the art will appreciate that the drawings provided herein are for illustration purposes and are not necessarily drawn to scale.

[0038] At the same time, it should be understood that in the following description, "circuit" refers to a conductive loop composed of at least one element or subcircuit through electrical connection or electromagnetic connection. When an element or circuit is said to be "connected to" another element or an element / circuit is said to be "connected between" two nodes, it can be directly coupled or connected to another element or there can be an intermediate element, and the connection between the elements can be physical, logical, or a combination thereof. On the contrary, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there is no intermediate element between the two.

[0039] Figure 2This is a circuit diagram of a first embodiment of a charging circuit of the present invention. The charging circuit includes a first input terminal IN, a first switch circuit 1, a second switch circuit 2 and a bidirectional buck-boost circuit 3. The first input terminal IN is used to receive an input signal. The first switch circuit 1 is coupled between the first input terminal IN and a first battery B1. The second switch circuit 2 is coupled between the first input terminal IN and a second battery B2. The bidirectional buck-boost circuit 3 is coupled between the first input terminal IN and a main battery Bm. When an external power source is connected, the input signal charges the first battery B1 and the second battery B2 respectively through the first switch circuit 1 and the second switch circuit 2, and charges the main battery Bm through the bidirectional buck-boost circuit 3. When no external power source is connected, the main battery Bm charges the first battery B1 through the bidirectional buck-boost circuit 3 and the first switch circuit 1, and charges the second battery B1 through the bidirectional buck-boost circuit 3 and the second switch circuit 2.

[0040] When the main battery Bm is charged, the bidirectional buck-boost circuit 3 works in the forward direction; when the main battery Bm is discharged, the bidirectional buck-boost circuit 3 works in the reverse direction.

[0041] The input signal is the output signal of a power supply (not shown in the figure), and the power supply can be a wired power supply or a wireless power supply. Furthermore, when the power supply is a wired power supply, it receives signals in the form of USB or the like and outputs the input signal; when the power supply is a wireless power supply, the power supply includes a power transmitting end and a power receiving end, and the power transmitting end receives the wireless input signal and outputs the input signal at the power receiving end. In one embodiment, the output voltage of the power supply can be fixed. In another embodiment, the output signal of the power supply can be adjusted. The power supply has a control circuit inside for controlling the input signal output by the power supply.

[0042] The bidirectional buck-boost circuit 3 includes a switch tube S1, a switch tube S2, a switch tube S3, a switch tube S4 and an inductor L1, wherein the switch tube S1 and the switch tube S2 are connected in series at the first end of the bidirectional buck-boost circuit, the switch tube S4 and the switch tube S3 are connected in series at the second end of the bidirectional buck-boost circuit, one end of the inductor L1 is connected to the common end of the switch tube S1 and the switch tube S2, and the other end of the inductor L1 is connected to the common end of the switch tube S3 and the switch tube S4. The high potential end of the first end of the bidirectional buck-boost circuit is connected to the common end of the first switch circuit 1, the second switch circuit 2 and the first input end IN, and the low potential end thereof is grounded, and the high potential end of the second end of the bidirectional buck-boost circuit is coupled to the main battery Bm, and the low potential end thereof is grounded.

[0043] In this embodiment, when an external power source is connected, the input signal charges the first battery B1 through the first switch circuit 1, and the input signal charges the second battery B2 through the second switch circuit 2. When an external power source is connected, the input signal charges the first battery B1 and the second battery B2 through a primary circuit (the first switch circuit 1 or the second switch circuit 2), and the charging efficiency at this time is equal to the efficiency of the first switch circuit 1 or the second switch circuit 2; while in the prior art, the input signal charges the first battery B1 and the second battery B2 through a three-stage circuit (buck circuit, boost circuit and linear charging module), and the charging efficiency at this time is equal to the product of the efficiency of the buck circuit, the efficiency of the boost circuit and the efficiency of the linear charging module, and the efficiency of each circuit or module is less than 1. Since the efficiency of the first switch circuit 1 or the second switch circuit 2 is greater than or equal to the efficiency of the linear charging module, the charging efficiency of the input signal to the first battery B1 and the second battery B2 in this embodiment is higher than that in the prior art.

[0044] There are two implementations of the input signal charging the first battery B1 and the second battery B2 respectively through the first switch circuit 1 and the second switch circuit 2 .

[0045] In a first implementation, when an external power source is connected, the first switch circuit 1 and the second switch circuit 2 work in a linear state to charge the first battery B1 and the second battery B2 respectively. Further, the resistance value of the first switch circuit 1 is controlled by controlling the voltage at the control end of the first switch circuit 1 to adjust the voltage of the first battery B1 and the current flowing through the first switch circuit 1; the resistance value of the second switch circuit 2 is controlled by controlling the voltage at the control end of the second switch circuit 2 to adjust the voltage of the second battery B2 and the current flowing through the second switch circuit 2. In this implementation, the input signal can be an output signal of a power supply with a fixed output voltage, or an output signal of a power supply with an adjustable output signal.

[0046] At the same time, the input signal charges the main battery Bm through the bidirectional buck-boost circuit 3. In the first implementation mode, if the input signal can be the output signal of a power supply with a fixed output voltage, the bidirectional buck-boost circuit 3 works in the forward direction in the buck mode. Specifically, the switch tube S4 is turned on, the switch tube S3 is turned off, and the switch tube S1 and the switch tube S2 work in the PWM state, so that the switch tube S1, the switch tube S2 and the inductor L1 work in the buck state. At this time, the bidirectional buck-boost circuit 3 can be replaced by a bidirectional buck circuit (a buck circuit in the forward direction and a boost circuit in the reverse direction), and the bidirectional buck circuit works in the forward buck state. If the input signal is the output signal of a power supply with an adjustable output signal, the bidirectional buck-boost circuit 3 works in the forward direction in the buck-boost state. Specifically, the switch tube S1, the switch tube S2, the switch tube S3 and the switch tube S4 operate in a PWM state, and by controlling the duty cycle of the switch tube S1, the switch tube S2, the switch tube S3 and the switch tube S4, the bidirectional buck-boost circuit operates in a boost or buck mode to charge the main battery Bm.

[0047] In a second implementation, when an external power source is connected, the first battery B1 and / or the second battery B2 are first charged with a constant current for fast charging. When the voltage of the first battery B1 and / or the second battery reaches a corresponding reference voltage, the first battery B1 and the second battery B2 are charged with a constant voltage. In this implementation, the input signal is an output signal of a power supply whose output signal is adjustable.

[0048] Furthermore, the input signal includes an input voltage and an input current. When the first battery B1 and / or the second battery B2 are charged with a constant current, the input current is constant and the input voltage gradually increases. When the first battery B1 and the second battery B2 are charged with a constant voltage, the input voltage is constant and the input current gradually decreases.

[0049] Further, when the first battery B1 and / or the second battery B2 are charged with a constant current, the input voltage increases as the voltage of the first battery B1 or the second battery B2 increases. Preferably, the input voltage is equal to the sum of the voltage of the first battery B1 or the second battery B2 and the voltage drop when the corresponding first switch circuit 1 or the second switch circuit 2 is turned on, that is, the input voltage is equal to the sum of the voltage of the first battery B1 and the voltage drop when the first switch circuit 1 is turned on, or the input voltage is equal to the sum of the voltage of the second battery B2 and the voltage drop when the second switch circuit 2 is turned on.

[0050] If the voltage of the first battery B1 and the voltage of the second battery B2 are not much different, then:

[0051] When the input current is constant and the input voltage gradually increases, the first battery B1 and the second battery B2 are charged with a constant current, and the first switch circuit 1 and the second switch circuit 2 both operate in an on state; when the input voltage is constant and the input current gradually decreases, the first battery B1 and the second battery B2 are charged with a constant voltage, and the first switch circuit 1 and the second switch circuit 2 operate in a linear state.

[0052] Specifically, when the voltage of the first battery B1 and the voltage of the second battery B2 are not much different, the input current is constant, and when the input voltage gradually increases, the first battery B1 and the second battery B2 are charged with a constant current, the first switch circuit 1 and the second switch circuit 2 are both operated in a conducting state, and the input voltage increases as the voltage of the first battery B1 or the second battery B2 increases. Preferably, the input voltage is equal to the sum of the voltage of the first battery B1 or the second battery B2 and the voltage drop of the corresponding first switch circuit 1 or the second switch circuit 2 when it is turned on; when the voltage of the first battery B1 or the voltage of the second battery B2 reaches the corresponding reference voltage, the input voltage is constant, the input current gradually decreases, the first battery B1 and the second battery B2 are charged with a constant voltage, and at this time, the first switch circuit 1 and the second switch circuit 2 operate in a linear state.

[0053] If the voltage of the first battery B1 and the voltage of the second battery B2 differ greatly, the increase of the input voltage includes the following two situations:

[0054] 1. The input voltage gradually increases as the voltage of the battery with a higher voltage between the first battery B1 and the second battery B2 increases.

[0055] When the input voltage increases gradually and the input current is constant, the input voltage increases gradually with the voltage of the battery with the higher voltage between the two, and the first battery B1 and the second battery B2 are charged with a constant current, and the switch circuit corresponding to the battery with the higher voltage between the two is always working in the on state. The switch circuit corresponding to the battery with the lower voltage between the two may enter a linear state to prevent the battery from overcharging due to excessive charging current. Further, the switch circuit corresponding to the battery with the lower voltage between the two is always working in a linear state, or first works in a linear state and then works in a conducting state. When the input voltage is constant and the input current decreases gradually, the first battery B1 and the second battery B2 are charged with a constant voltage, and the first switch circuit 1 and the second switch circuit 2 are working in a linear state. Preferably, the input voltage is equal to the sum of the voltage of the battery with the higher voltage between the two and the voltage drop when the corresponding switch circuit is turned on.

[0056] Specifically, when the voltage of the first battery B1 and the voltage of the second battery B2 differ greatly, the input voltage is controlled to increase gradually, the input current is constant, and the input voltage gradually increases with the voltage of the battery with a higher voltage between the first battery B1 and the second battery B2, and the first battery B1 and the second battery B2 are charged with a constant current. In the interval where the input current is constant and the input voltage gradually increases, the switch circuit corresponding to the battery with a higher voltage between the two batteries is always operating in the on state in this interval, and the switch circuit corresponding to the battery with a lower voltage between the two batteries first operates in the linear state, until the voltage difference between the first battery B1 and the second battery B2 is not large (for example, the voltage difference between the first battery B1 and the second battery B2 reaches the first threshold), the switch circuit corresponding to the battery with a lower voltage between the two batteries is operating in the on state; if the voltage difference between the first battery B1 and the second battery B2 is always large (for example, the voltage difference between the first battery B1 and the second battery B2 does not reach the first threshold in this interval) in the interval where the input current is constant and the input voltage gradually increases, the switch circuit corresponding to the battery with a lower voltage between the two batteries is always operating in the linear state. The input voltage gradually increases. When the voltage of the battery with a higher voltage among the two reaches the first reference voltage, the input voltage is controlled to be constant, the first battery B1 and the second battery B2 are charged at a constant voltage, and the first switch circuit 1 and the second switch circuit 2 operate in a linear state.

[0057] 2. The input voltage gradually increases as the voltage of the battery with the lower voltage between the first battery B1 and the second battery B2 increases.

[0058] When the input current is constant and the input voltage gradually increases with the voltage of the battery with the lower voltage among the first battery B1 and the second battery B2, the battery with the lower voltage among the two operates in a constant current state. In the interval where the input current is constant and the input voltage gradually increases, the switch circuit corresponding to the battery with the lower voltage among the two operates in a conducting state in this interval. If the input voltage is initially higher than the voltage of the battery with the higher voltage among the two, the battery with the higher voltage among the two operates in a linear state (at this time, the battery with the higher voltage among the two is not charged with a constant current), or the battery with the higher voltage among the two first operates in a linear state (at this time, the battery with the higher voltage among the two is not charged with a constant current), and then operates in a conducting state (at this time, the battery with the higher voltage among the two is charged with a constant current). If the input voltage is initially lower than the voltage of the battery with the higher voltage, the battery with the higher voltage does not work first, and then works in the on state (the battery with the higher voltage is charged with constant current at this time), or does not work first, and then works in the linear state (the battery with the higher voltage is not charged with constant current at this time), or does not work first, and then works in the linear state (the battery with the higher voltage is not charged with constant current at this time), and finally works in the on state (the battery with the higher voltage is charged with constant current at this time). The input voltage is controlled to be constant, and the input current is gradually reduced. The first battery B1 and the second battery B2 are charged with constant voltage, and the first switch circuit 1 and the second switch circuit 2 work in a linear state. Preferably, the input voltage is equal to the sum of the voltage of the battery with the lower voltage and the voltage drop when the corresponding switch circuit is turned on.

[0059] Specifically, when the input current is constant and the input voltage gradually increases with the voltage of the battery with the lower voltage between the first battery B1 and the second battery B2, the battery with the lower voltage between the two batteries always works in a constant current state. In the interval where the input current is constant and the input voltage gradually increases, the switch circuit corresponding to the battery with the lower voltage between the two batteries always works in a conducting state in this interval.

[0060] If the input voltage is higher than the voltage of the battery with the higher voltage of the two batteries at the beginning, the battery with the higher voltage of the two batteries first operates in a linear state, and at this time, the battery with the higher voltage of the two batteries is non-constant current charged until the voltage difference between the first battery B1 and the second battery B2 is not much (for example, the difference between the voltages of the first battery B1 and the second battery B2 reaches a first threshold), and the switch circuit corresponding to the battery with the higher voltage of the two batteries operates in a conducting state, and at this time, the battery with the higher voltage of the two batteries is charged with a constant current; if in an interval where the input current is constant and the input voltage gradually increases, the voltage difference between the first battery B1 and the second battery B2 is always large (for example, the difference between the voltages of the first battery B1 and the second battery B2 does not reach the first threshold in this interval), then in this interval, the switch circuit corresponding to the battery with the higher voltage of the two batteries always operates in a linear state.

[0061] If the input voltage is initially lower than the voltage of the battery with the higher voltage among the two, the battery with the higher voltage among the two does not work first. When the input voltage increases to be greater than the voltage of the battery with the higher voltage among the two, the switch circuit corresponding to the battery with the higher voltage among the two works in a linear state. At this time, the battery with the higher voltage among the two is non-constant current charged. Until the voltage difference between the first battery B1 and the second battery B2 is not large (for example, the difference between the voltages of the first battery B1 and the second battery B2 reaches a first threshold), the switch circuit corresponding to the battery with the higher voltage among the two works in a conducting state. At this time, the battery with the higher voltage among the two is charged with a constant current. If the voltage difference between the first battery B1 and the second battery B2 is always large in the interval where the input current is constant and the input voltage gradually increases (for example, the difference between the voltages of the first battery B1 and the second battery B2 does not reach the first threshold in this interval), then after the input voltage increases to be greater than the voltage of the battery with the higher voltage among the two, the switch circuit corresponding to the battery with the higher voltage among the two works in a linear state. Or the battery with higher voltage among the two does not work first, until the voltage of the battery with lower voltage among the two rises to a voltage that is not much different from the voltage of the battery with higher voltage among the two (for example, the difference between the voltages of the first battery B1 and the second battery B2 reaches the first threshold), the switch circuit corresponding to the battery with higher voltage among the two works in the on state, and the battery with higher voltage among the two is charged with constant current at this time. The input voltage gradually rises, and when the voltage of the battery with higher voltage among the two reaches the second reference voltage, the input voltage is controlled to be constant, the first battery B1 and the second battery B2 are charged with constant voltage, and the first switch circuit 1 and the second switch circuit 2 work in a linear state. The first reference voltage and the second reference voltage may be the same or different, and the present invention is not limited to this.

[0062] Furthermore, the second implementation is a fast charging process, and the charging rate of the input signal to charge the first battery B1 and the second battery B2 is higher in the second implementation of this embodiment than in the prior art.

[0063] At the same time, the input signal charges the main battery Bm through the bidirectional buck-boost circuit 3. In the second implementation, since the input voltage gradually increases, there may be a situation where the input voltage is less than the main battery voltage, so at this time the bidirectional buck-boost circuit 3 works in the forward direction in the buck-boost state. Specifically, the switch tube S1, the switch tube S2, the switch tube S3 and the switch tube S4 work in the PWM state, and by controlling the duty cycle of the switch tube S1, the switch tube S2, the switch tube S3 and the switch tube S4, the bidirectional buck-boost circuit works in the boost or buck mode to charge the main battery Bm.

[0064] In this embodiment, when no external power supply is connected, the bidirectional buck-boost circuit 3 works in reverse, and the main battery Bm charges the first battery B1 through the bidirectional buck-boost circuit 3 and the first switch circuit 1, and charges the second battery B1 through the bidirectional buck-boost circuit 3 and the second switch circuit 2.

[0065] There are three implementations of the main battery Bm charging the first battery B1 or the second battery B2 through the bidirectional buck-boost and the first switch circuit 1 or the second switch circuit 2 .

[0066] In a first implementation, when no external power source is connected, the bidirectional buck-boost circuit 3 works in reverse, and the main battery Bm generates a fixed voltage through the bidirectional buck-boost circuit 3 to charge the first battery B1 and the second battery B2, and at this time, the first switch circuit 1 and the second switch circuit 2 work in a linear state. In the first implementation, the bidirectional buck-boost circuit 3 can be replaced by a bidirectional buck circuit, and at this time, the bidirectional buck works in a reverse boost state to generate a fixed voltage.

[0067] In a second implementation, when no external power source is connected, the bidirectional buck-boost circuit 3 works in reverse, and the main battery Bm charges the first battery B1 and the second battery B2 in a time-sharing manner through the bidirectional buck-boost circuit 3. Further, when no external power source is connected, the main battery Bm charges the first battery B1 in one switching cycle and charges the second battery B2 in the next switching cycle through the bidirectional buck-boost circuit 3. Further, during a part of a switching cycle, the main battery Bm charges the inductor L1, and during another part of a switching cycle, the first switch circuit 1 works in a conducting state, and the inductor L1 charges the first battery B1; during a part of the next switching cycle, the main battery Bm charges the inductor L1, and during another part of the next switching cycle, the second switch circuit 2 works in a conducting state, and the inductor L1 charges the second battery B2. In the second implementation, the efficiency of the main battery Bm charging the first battery B1 and the second battery B2 is equal to the efficiency of the bidirectional buck-boost circuit, while in the prior art, the efficiency of the main battery charging the first battery B1 and the second battery B2 is equal to the product of the efficiency of the boost circuit and the efficiency of the linear charging module, so that the charging efficiency of the main battery Bm charging the first battery B1 and the second battery B2 is higher in the second implementation of this embodiment than in the prior art. Moreover, when the voltage of the first battery B1 and the voltage of the second battery B2 differ greatly, the first battery B1 and the second battery B2 are charged in a time-sharing manner in this embodiment, which is more advantageous than the technical solution of charging the first battery B1 and the second battery B2 at the same time. In this embodiment, when the first battery B1 and the second battery B2 are charged in a time-sharing manner, the voltage of the first battery B1 and the voltage of the second battery B2 may differ greatly or slightly, and the present invention does not limit this. At the same time, in the second implementation, the charging rate of the main battery Bm charging the first battery B1 and the second battery B2 is higher than that of the prior art.

[0068] Specifically, during a part of a switching cycle, the switch tube S4 is turned on, and the switch tube S2 is turned on, so that the main battery Bm charges the inductor L1. During another part of a switching cycle, the switch tube S1 is turned on, and the switch tube S3 is turned on, and the first switch circuit 1 works in a conducting state, so that the inductor L1 charges the first battery B1. During a part of the next switching cycle, the switch tube S4 is turned on, and the switch tube S2 is turned on, so that the main battery Bm charges the inductor L1. During another part of the next switching cycle, the switch tube S1 is turned on, and the switch tube S3 is turned on, and the second switch circuit 2 works in a conducting state, so that the inductor L1 charges the second battery B2.

[0069] In a third implementation, when no external power source is connected, the second end of the bidirectional buck-boost circuit receives the voltage of the main battery Bm, and generates a first voltage and a first current at its first end to charge the first battery B1 and the second battery B2. Further, the first battery B1 and / or the second battery B2 are first charged with a constant current for fast charging, and when the voltage of the first battery B1 and / or the second battery reaches the corresponding reference voltage, the first battery B1 and the second battery B2 are charged with a constant voltage. Further, when the first battery B1 and / or the second battery B2 are charged with a constant current, the first current is controlled to be constant, and the first voltage is controlled to increase gradually, and when the first battery B1 and the second battery B2 are charged with a constant voltage, the first voltage is controlled to be constant, and the first current is controlled to decrease gradually. Further, when the first battery B1 and / or the second battery B2 are charged with a constant current, the first voltage increases as the voltage of the first battery B1 or the second battery B2 increases. Preferably, the first voltage is equal to the sum of the voltage of the first battery B1 or the second battery B2 and the voltage drop when the corresponding first switch circuit 1 or the second switch circuit 2 is turned on, that is, the first voltage is equal to the sum of the voltage of the first battery B1 and the voltage drop when the first switch circuit 1 is turned on, or the first voltage is equal to the sum of the voltage of the second battery B2 and the voltage drop when the second switch circuit 2 is turned on.

[0070] If the voltage of the first battery B1 and the voltage of the second battery B2 are not much different, then:

[0071] When the first current is constant and the first voltage gradually increases, the first battery B1 and the second battery B2 are charged with a constant current, and the first switch circuit 1 and the second switch circuit 2 both operate in an on state; when the first voltage is constant and the first current gradually decreases, the first battery B1 and the second battery B2 are charged with a constant voltage, and the first switch circuit 1 and the second switch circuit 2 operate in a linear state.

[0072] Specifically, when the voltage of the first battery B1 and the voltage of the second battery B2 are not much different, the first current is constant, and when the first voltage gradually increases, the first battery B1 and the second battery B2 are charged with a constant current, the first switch circuit 1 and the second switch circuit 2 are both operated in a conducting state, and the first voltage increases as the voltage of the first battery B1 or the second battery B2 increases. Preferably, the first voltage is equal to the sum of the voltage of the first battery B1 or the second battery B2 and the voltage drop of the corresponding first switch circuit 1 or the second switch circuit 2 when it is turned on; when the voltage of the first battery B1 or the second battery B2 reaches the corresponding reference voltage, the first voltage is constant, the first current gradually decreases, the first battery B1 and the second battery B2 are charged with a constant voltage, and at this time, the first switch circuit 1 and the second switch circuit 2 operate in a linear state.

[0073] If the voltage of the first battery B1 and the voltage of the second battery B2 differ greatly, the increase of the first voltage includes the following two situations:

[0074] 1. The first voltage gradually increases as the voltage of the battery with a higher voltage between the first battery B1 and the second battery B2 increases.

[0075] When the first voltage increases gradually and the first current is constant, the first voltage increases gradually with the voltage of the battery with the higher voltage between the two, the first battery B1 and the second battery B2 are charged with a constant current, and the switch circuit corresponding to the battery with the higher voltage between the two is always working in the on state. The switch circuit corresponding to the battery with the lower voltage between the two may enter a linear state to prevent the battery from overcharging due to excessive charging current. Further, the switch circuit corresponding to the battery with the lower voltage between the two is always working in a linear state, or first works in a linear state and then works in a conducting state. When the first voltage is constant and the first current decreases gradually, the first battery B1 and the second battery B2 are charged with a constant voltage, and the first switch circuit 1 and the second switch circuit 2 are working in a linear state. Preferably, the first voltage is equal to the sum of the voltage of the battery with the higher voltage between the two and the voltage drop when the corresponding switch circuit is turned on.

[0076] Specifically, when the voltage of the first battery B1 and the voltage of the second battery B2 differ greatly, the first voltage is controlled to increase gradually, the first current is constant, and the first voltage gradually increases with the voltage of the battery with a higher voltage between the first battery B1 and the second battery B2, and the first battery B1 and the second battery B2 are charged with a constant current. In the interval where the first current is constant and the first voltage gradually increases, the switch circuit corresponding to the battery with a higher voltage between the two batteries is always operating in the on state in this interval, and the switch circuit corresponding to the battery with a lower voltage between the two batteries first operates in the linear state, until the voltage difference between the first battery B1 and the second battery B2 is not large (for example, the voltage difference between the first battery B1 and the second battery B2 reaches the first threshold), the switch circuit corresponding to the battery with a lower voltage between the two batteries is operating in the on state; if in the interval where the first current is constant and the first voltage gradually increases, the voltage difference between the first battery B1 and the second battery B2 is always large (for example, the voltage difference between the first battery B1 and the second battery B2 does not reach the first threshold in this interval), the switch circuit corresponding to the battery with a lower voltage between the two batteries is always operating in the linear state. The first voltage gradually increases, and when the voltage of the battery with a higher voltage between the two reaches the first reference voltage, the first voltage is controlled to be constant, the first battery B1 and the second battery B2 are charged at a constant voltage, and the first switch circuit 1 and the second switch circuit 2 operate in a linear state.

[0077] 2. The first voltage gradually increases as the voltage of the battery with a lower voltage between the first battery B1 and the second battery B2 increases.

[0078] When the first current is constant and the first voltage gradually increases with the voltage of the battery with the lower voltage among the first battery B1 and the second battery B2, the battery with the lower voltage among the two operates in a constant current state. In the interval in which the first current is constant and the first voltage gradually increases, the switch circuit corresponding to the battery with the lower voltage among the two operates in a conducting state in this interval. If the first voltage is initially higher than the voltage of the battery with the higher voltage among the two, the battery with the higher voltage among the two operates in a linear state (at this time, the battery with the higher voltage among the two is not charged with a constant current), or the battery with the higher voltage among the two first operates in a linear state (at this time, the battery with the higher voltage among the two is not charged with a constant current), and then operates in a conducting state (at this time, the battery with the higher voltage among the two is charged with a constant current). If the first voltage is initially lower than the voltage of the battery with the higher voltage, the battery with the higher voltage does not work first, and then works in a conducting state (at this time, the battery with the higher voltage is charged with a constant current), or does not work first, and then works in a linear state (at this time, the battery with the higher voltage is not charged with a constant current), or does not work first, and then works in a linear state (at this time, the battery with the higher voltage is not charged with a constant current), and finally works in a conducting state (at this time, the battery with the higher voltage is charged with a constant current). The first voltage is controlled to be constant, the first current is gradually reduced, the first battery B1 and the second battery B2 are charged with a constant voltage, and the first switch circuit 1 and the second switch circuit 2 work in a linear state. Preferably, the first voltage is equal to the sum of the voltage of the battery with the lower voltage and the voltage drop when its corresponding switch circuit is turned on.

[0079] Specifically, when the first current is constant and the first voltage gradually increases with the voltage of the battery with the lower voltage between the first battery B1 and the second battery B2, the battery with the lower voltage between the two batteries always works in a constant current state. In the interval where the first current is constant and the first voltage gradually increases, the switch circuit corresponding to the battery with the lower voltage between the two batteries always works in a conducting state in this interval.

[0080] If the first voltage is higher than the voltage of the battery with the higher voltage of the two batteries at the beginning, the battery with the higher voltage of the two batteries first operates in a linear state, and at this time, the battery with the higher voltage of the two batteries is charged at a non-constant current until the voltage difference between the first battery B1 and the second battery B2 is not much (for example, the difference between the voltages of the first battery B1 and the second battery B2 reaches a first threshold), and the switch circuit corresponding to the battery with the higher voltage of the two batteries operates in a conducting state, and at this time, the battery with the higher voltage of the two batteries is charged at a constant current; if in an interval where the first current is constant and the first voltage gradually increases, the voltage difference between the first battery B1 and the second battery B2 is always large (for example, the difference between the voltages of the first battery B1 and the second battery B2 does not reach the first threshold in this interval), then in this interval, the switch circuit corresponding to the battery with the higher voltage of the two batteries always operates in a linear state.

[0081] If the first voltage is initially lower than the voltage of the battery with the higher voltage among the two, the battery with the higher voltage among the two does not work first. When the first voltage increases to be greater than the voltage of the battery with the higher voltage among the two, the switch circuit corresponding to the battery with the higher voltage among the two works in a linear state. At this time, the battery with the higher voltage among the two is non-constant current charged. Until the voltage difference between the first battery B1 and the second battery B2 is not large (for example, the voltage difference between the first battery B1 and the second battery B2 reaches a first threshold), the switch circuit corresponding to the battery with the higher voltage among the two works in a conducting state. At this time, the battery with the higher voltage among the two is charged with a constant current. If in the interval where the first current is constant and the first voltage gradually increases, the voltage difference between the first battery B1 and the second battery B2 is always large (for example, the voltage difference between the first battery B1 and the second battery B2 does not reach the first threshold in this interval), then after the first voltage increases to be greater than the voltage of the battery with the higher voltage among the two, the switch circuit corresponding to the battery with the higher voltage among the two works in a linear state. Or the battery with the higher voltage among the two does not work first, until the voltage of the battery with the lower voltage among the two rises to a level that is not much different from the voltage of the battery with the higher voltage among the two (for example, the difference between the voltages of the first battery B1 and the second battery B2 reaches the first threshold), the switch circuit corresponding to the battery with the higher voltage among the two works in the on state, and the battery with the higher voltage among the two is charged with a constant current. The first voltage gradually rises, and when the voltage of the battery with the higher voltage among the two reaches the second reference voltage, the first voltage is controlled to be constant, the first battery B1 and the second battery B2 are charged with a constant voltage, and the first switch circuit 1 and the second switch circuit 2 work in a linear state. The first reference voltage and the second reference voltage may be the same or different, and the present invention is not limited to this.

[0082] In the third implementation, the main battery Bm and the bidirectional buck-boost circuit 3 can be regarded as an output adjustable power supply, and the first voltage and the first current output by the bidirectional buck-boost circuit 3 are the output signals of the output adjustable power supply. At this time, the bidirectional buck-boost circuit 3 works in reverse, and the bidirectional buck-boost circuit 3 works in a boost or buck state, and the duty cycle of the switch tube S1, the switch tube S2, the switch tube S3 and the switch tube S4 in the bidirectional buck-boost circuit 3 is adjusted to control the magnitude of the first voltage and the first current. Furthermore, in this embodiment, the duty cycle of the switch tube S1, the switch tube S2, the switch tube S3 and the switch tube S4 can be controlled by any voltage control and current control method. In the prior art, the efficiency of the main battery charging the first battery B1 and the second battery B2 is equal to the product of the efficiency of the boost circuit and the efficiency of the linear charging module. In the second implementation, when the first switch circuit 1 or the second switch circuit 2 works in the on state, the efficiency of the main battery Bm charging the first battery B1 and the second battery B2 is equal to the efficiency of the bidirectional buck-boost circuit 3. At this time, the charging efficiency of this embodiment is higher than that of the prior art; when the first switch circuit 1 or the second switch circuit 2 works in the linear state, the efficiency of the main battery Bm charging the first battery B1 and the second battery B2 is equal to the product of the efficiency of the bidirectional buck-boost circuit 3 and the efficiency of the first switch circuit 1 or the second switch circuit 2. At this time, the charging efficiency of this embodiment is not much different from that of the prior art. In the second implementation, the first switch circuit 1 or the second switch circuit 2 works in the on state for a period of time and in the linear state for another period of time, so that the charging efficiency of the main battery Bm charging the first battery B1 and the second battery B2 is higher in the second implementation of this embodiment than in the prior art. Furthermore, the second implementation includes a constant current charging process for fast charging, and the charging rate at which the main battery Bm charges the first battery B1 and the second battery B2 is higher in the third implementation of this embodiment than in the prior art.

[0083] In this embodiment, the first switch circuit 1 is a first switch tube SR, and the second switch circuit is a second switch tube SL. Only one implementation method is given, and the present invention is not limited to this. Optionally, in this embodiment, a third switch tube Sm is coupled between the second end of the bidirectional buck-boost circuit 3 and the main battery Bm to prevent the main battery Bm from being overcharged due to excessive charging current or excessive battery capacity. Specifically, when the voltage of the main battery Bm is greater than the first threshold voltage, the third switch tube Sm is turned off. Optionally, the first input terminal IN is coupled to the switch tube Sin. When an external power supply is connected, the switch tube Sin is turned on. When there is no external power supply, the switch tube Sin is turned off, which is used to prevent the output signal of the bidirectional buck-boost circuit from flowing back to the first input terminal when the main battery Bm charges the first battery B1 and the second battery B2 without an external power supply, so that the first input terminal has a signal output.

[0084] Furthermore, the present invention also provides an integrated circuit (chip) 01. Based on the above-mentioned charging circuit, the first switch circuit 1, the second switch circuit 2 and the switch tubes in the bidirectional buck-boost circuit 3 are integrated into the same integrated circuit. In this embodiment, the switch tube Sin, the first switch tube SR, the second switch tube SL, the switch tube S1, the switch tube S2, the switch tube S3, the switch tube S4, and the third switch tube Sm are integrated into the same integrated circuit. In addition, the integrated circuit 01 includes a first input port IN for receiving an input signal output by a wired power supply or an input signal output by a wireless power supply. The integrated circuit 01 also includes a first output port BATR, a second output port BATL and a third output port BATM, which are used to couple the first battery B1, the second battery B2 and the main battery Bm respectively.

[0085] Figure 3 A circuit diagram of a second embodiment of a charging circuit of the present invention is provided, which differs from the first embodiment in that: the charging circuit includes a first input terminal IN and a second input terminal RX, the first input terminal IN is used to receive an input signal output by a wired power source, and the second input terminal RX is used to receive an input signal output by a wireless power source. The first input terminal IN and the second input terminal RX are respectively coupled to a switch tube Sin and a switch tube Srx, so as to prevent the first input terminal IN and the second input terminal RX from outputting a signal.

[0086] Specifically, when an external wired power supply is connected, the switch tube Sin is turned on, and when no external wired power supply is connected, the switch tube Sin is turned off; when an external wireless power supply is connected, the switch tube Srx is turned on, and when no external wireless power supply is connected, the switch tube Srx is turned off, so as to prevent a signal from flowing between the first input terminal IN and the second input terminal RX, and to prevent the output signal of the bidirectional buck-boost circuit from flowing back to the first input terminal IN or the second input terminal RX when the main battery Bm charges the first battery B1 and the second battery B2 without an external power supply.

[0087] Furthermore, in this embodiment, the integrated circuit 01 includes a first input port IN and a second input port RX, the first input port IN is used to receive an input signal output by a wired power source, and the second input port RX is used to receive an input signal output by a wireless power source.

[0088] The charging circuit of the present invention has a SIMO (single-inductor, multiple-output) structure, and only one integrated circuit (chip) is needed to complete the functions that the prior art requires four chips to complete, and only one inductor is needed, which reduces the volume and cost of the circuit. In addition, the charging circuit of the present invention improves the charging efficiency and charging rate of each charging process (including the charging process of the first battery and the second battery when an external power source is connected, the charging process of the main battery when an external power source is connected, and the main battery charging the first battery and the second battery), further optimizes the heat dissipation of the system, extends the life of the main battery, and reduces the cost. Since the main battery in the present invention has better efficiency in charging the first battery and the second battery than the prior art, the service life of the main battery is extended. Under the condition that the capacity of the main battery is the same, after the main battery is fully charged, the main battery of the charging circuit of the present invention can charge the first battery and the second battery in more charging cycles.

[0089] In addition, the charging circuit of the present invention has two independent outputs and can charge two independent batteries. When the charging circuit of the present invention charges headphones (such as TWS headphones), the first battery and the second battery are respectively located in the left and right earplugs of the headphones, and the main battery is located in the battery box. Furthermore, the charging circuit of the present invention can be used not only in headphones, but also in other devices. The charging circuit of the present invention is used to charge independent dual batteries, and the first battery and the second battery can be in two different terminals (such as the left and right ears of the headphones), or they can be opposite-sex batteries in the same terminal, that is, the capacity of the first battery and the second battery is quite different, such as a battery in a terminal with a capacity of 100mAh and a battery with a capacity of only 50mAh.

[0090] In an embodiment of the present invention, the switch tube can adopt various existing electrically controllable switch devices, such as a metal oxide semiconductor field effect transistor (MOSFET), a bipolar junction transistor (BJT), or an insulated gate bipolar transistor (IGBT), and the present invention is not limited to this.

[0091] Although the embodiments or implementations are described and explained separately above, some common technologies are involved. It is the opinion of ordinary technicians in this field that the embodiments or implementations can be replaced and integrated between them. If one of the embodiments or implementations is not clearly recorded, reference can be made to another recorded embodiment.

[0092] According to the embodiments of the present invention as described above, these embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and changes can be made based on the above description. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can make good use of the present invention and the modified use based on the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A charging circuit, characterized in that: include: A first input terminal, used for receiving an input signal; A first switch circuit, coupled between the first input terminal and a first battery; a second switch circuit coupled between the first input terminal and a second battery; a bidirectional buck-boost circuit coupled between the first input terminal and a main battery; When an external power source is connected, the input signal charges the first battery and the second battery respectively through the first switch circuit and the second switch circuit, and charges the main battery through the bidirectional buck-boost circuit. At this time, the bidirectional buck-boost circuit works in the forward direction; at this time, The first switch circuit and the second switch circuit operate in a linear state to charge the first battery and the second battery respectively; or The first battery and / or the second battery are first charged with a constant current to perform fast charging, and when the voltage of the first battery and / or the second battery reaches a corresponding reference voltage, the first battery and the second battery are charged with a constant voltage; When no external power source is connected, the main battery charges the first battery through the bidirectional buck-boost circuit and the first switch circuit, and charges the second battery through the bidirectional buck-boost circuit and the second switch circuit. At this time, the bidirectional buck-boost circuit works in reverse. at this time, The first switch circuit and the second switch circuit operate in a linear state, and the main battery charges the first battery and the second battery respectively; or The main battery charges the first battery and the second battery in a time-sharing manner through the bidirectional buck-boost circuit; or The first battery and / or the second battery are first charged with a constant current to perform fast charging. When the voltage of the first battery and / or the second battery reaches a corresponding reference voltage, the first battery and the second battery are charged with a constant voltage.

2. The charging circuit according to claim 1, characterized in that: When no external power source is connected, the main battery charges the first battery and the second battery in a time-sharing manner through the bidirectional buck-boost circuit.

3. The charging circuit according to claim 1, characterized in that: When no external power source is connected, when the main battery charges the first battery and the second battery in a time-sharing manner through the bidirectional buck-boost circuit, the main battery charges the first battery in one switching cycle and charges the second battery in the next switching cycle through the bidirectional buck-boost circuit.

4. The charging circuit according to claim 3, characterized in that: The bidirectional buck-boost circuit includes an inductor. When no external power supply is connected, during a part of a switching cycle, the main battery charges the inductor, and during another part of a switching cycle, the first switching circuit works in an on state, and the inductor charges the first battery; during a part of the next switching cycle, the main battery charges the inductor, and during another part of the next switching cycle, the second switching circuit works in an on state, and the inductor charges the second battery.

5. The charging circuit according to claim 1, characterized in that: When no external power supply is connected, the second end of the bidirectional buck-boost circuit receives the voltage of the main battery, and generates a first voltage and a first current at the first end thereof to charge the first battery and the second battery; the first battery and / or the second battery are firstly charged with a constant current for fast charging; when the voltage of the first battery and / or the second battery reaches a corresponding reference voltage, the first battery and the second battery are charged with a constant voltage.

6. The charging circuit according to claim 5, characterized in that: When the first current is controlled to be constant and the first voltage is controlled to increase gradually, the first battery and / or the second battery are charged with a constant current; when the first voltage is controlled to be constant, the first battery and the second battery are charged with a constant voltage.

7. The charging circuit according to claim 6, characterized in that: When the first battery and / or the second battery is charged with a constant current, the first voltage is controlled to increase as the voltage of the first battery or the second battery increases.

8. The charging circuit according to claim 1, characterized in that: When an external power source is used, the input signal includes an input voltage and an input current. When the input current is constant and the input voltage increases gradually, the first battery and / or the second battery is charged with a constant current. When the input voltage is constant, the first battery and the second battery are charged at a constant voltage.

9. The charging circuit according to claim 8, characterized in that: When the first battery and / or the second battery is charged with a constant current, the input voltage increases as the voltage of the first battery or the second battery increases.

10. The charging circuit according to claim 1, characterized in that: When an external power supply is connected, the input signal includes an input voltage and an input current. When no external power supply is connected, the second end of the bidirectional buck-boost circuit receives the voltage of the main battery and generates a first voltage and a first current at its first end. When the input current or the first current is constant and the input voltage or the first voltage gradually increases, the first battery and the second battery are charged with a constant current, and the first switch circuit and the second switch circuit operate in an on state.

11. The charging circuit according to claim 1, characterized in that: When an external power supply is connected, the input signal includes an input voltage and an input current. When no external power supply is connected, the second end of the bidirectional buck-boost circuit receives the voltage of the main battery and generates a first voltage and a first current at its first end. When the input current or the first current is constant and the input voltage or the first voltage gradually increases, the first battery and the second battery are charged with a constant current, and the switch circuit corresponding to the battery with a higher voltage between the first battery and the second battery operates in a conducting state, and the switch circuit corresponding to the battery with a lower voltage between the first battery and the second battery operates in a linear state, or first operates in a linear state and then operates in a conducting state.

12. The charging circuit according to claim 1, characterized in that: When an external power supply is connected, the input signal includes an input voltage and an input current. When no external power supply is connected, the second end of the bidirectional buck-boost circuit receives the voltage of the main battery and generates a first voltage and a first current at its first end. When the input current or the first current is constant and the input voltage or the first voltage gradually increases, the battery with a lower voltage between the first battery and the second battery is charged with a constant current, and the switch circuit corresponding to the battery with a lower voltage between the first battery and the second battery operates in a conducting state, and the switch circuit corresponding to the battery with a higher voltage between the first battery and the second battery does not work first and then works in a linear state, or does not work first and then works in a conducting state, or does not work first and then works in a linear state, and finally works in a conducting state.

13. The charging circuit according to claim 1, characterized in that: When an external power supply is connected, the input signal includes an input voltage and an input current. When no external power supply is connected, the second end of the bidirectional buck-boost circuit receives the voltage of the main battery and generates a first voltage and a first current at its first end. When the input current or the first current is constant and the input voltage or the first voltage gradually increases, the battery with a lower voltage between the first battery and the second battery is charged with a constant current, and the switch circuit corresponding to the battery with a lower voltage between the first battery and the second battery operates in a conducting state, and the switch circuit corresponding to the battery with a higher voltage between the first battery and the second battery first operates in a linear state, or first operates in a linear state and then operates in a conducting state.

14. The charging circuit according to claim 1, characterized in that: When an external power supply is connected, the input signal includes an input voltage and an input current. When no external power supply is connected, the second end of the bidirectional buck-boost circuit receives the voltage of the main battery and generates a first voltage and a first current at its first end. When the input voltage or the first voltage is constant, the first battery and the second battery are charged at a constant voltage, and the first switch circuit and the second switch circuit operate in a linear state.

15. The charging circuit according to claim 1, characterized in that: When an external power source is connected, the first switch circuit and the second switch circuit work in a linear state to charge the first battery and the second battery respectively, and the voltage of the first battery and the current flowing through the first switch circuit are adjusted by controlling the voltage of the control terminal of the first switch circuit to control the resistance value of the first switch circuit; The voltage of the second battery and the current flowing through the second switch circuit are adjusted by controlling the voltage of the control terminal of the second switch circuit to control the resistance value of the second switch circuit.

16. The charging circuit according to claim 1, characterized in that: The first switch circuit is a first switch tube, and the second switch circuit is a second switch tube.

17. The charging circuit according to claim 1, characterized in that: The charging circuit also includes a second input terminal, the first input terminal is used to receive an input signal output by a wired power source, and the second input terminal is used to receive an input signal output by a wireless power source.

18. The charging circuit according to claim 17, characterized in that: The first input terminal and the second input terminal are respectively coupled to a switch tube, which is used to prevent the first input terminal and the second input terminal from having a signal output.

19. The charging circuit according to claim 1, characterized in that: A third switch tube is coupled between the second end of the bidirectional buck-boost circuit and the main battery, and when the voltage of the main battery is greater than a first threshold voltage, the third switch tube is turned off.

20. An integrated circuit, based on the charging circuit according to any one of claims 1 to 19, characterized in that: The first switch circuit, the second switch circuit and the switch tube in the bidirectional buck-boost circuit are integrated in the same integrated circuit.

21. The integrated circuit according to claim 20, characterized in that: The integrated circuit comprises a first input port for receiving an input signal output by a wired power source or an input signal output by a wireless power source.

22. The integrated circuit according to claim 20, characterized in that: The integrated circuit includes a first input port and a second input port, the first input port is used to receive an input signal output by a wired power source, and the second input port is used to receive an input signal output by a wireless power source.

23. The integrated circuit according to claim 20, characterized in that: The integrated circuit includes a first output port, a second output port, and a third output port for respectively coupling to the first battery, the second battery, and the main battery.

Images