Charging circuit

Abstract

The embodiment of the present application discloses a charging circuit, the charging circuit comprises a first port configured to couple a first voltage source in a first working condition; a second port configured to couple a first battery; and a power stage circuit configured to work in a form of a switched capacitor converter in a first mode and in a form of a buck converter in a second mode to charge the first battery, wherein the switched capacitor converter and the buck converter share part of power tubes. The charging circuit of the present application only needs one circuit to work in the form of the switched capacitor converter and the form of the buck converter, has less switching tubes, improves the integration and power density of the system, and has simple control and low cost.

Description

Technical Field

[0001] This invention relates to the field of power electronics, and more specifically, to a charging circuit. Background Technology

[0002] With the widespread use of mobile phones, tablets, and Bluetooth headsets, higher demands are placed on charging efficiency. Compared to traditional converter topologies, switched-capacitor circuits (i.e., charge pumps) are widely used in mainstream fast charging solutions due to their ultra-high efficiency. However, during charging, the input and output voltages of the switched-capacitor circuit maintain a fixed ratio, thus requiring adjustment of the input voltage based on the battery voltage. However, when the battery is undervoltage, the system does not operate, and the battery voltage cannot be determined, making charging using the switched-capacitor circuit impossible. Existing technology utilizes buck circuits to pre-charge the battery and power the system for rapid startup.

[0003] However, in existing technologies, the switched capacitor circuit and the buck circuit are two independent circuits, resulting in more switching transistors, lower integration, lower power density, more complex control, and higher cost. Summary of the Invention

[0004] In view of this, the present invention proposes a charging circuit to solve the technical problems of existing technologies, such as a large number of switching transistors, low integration, low power density, complex control, and high cost.

[0005] This invention provides a charging circuit comprising: a first port configured to be coupled to a first voltage source in a first operating state; a second port configured to be coupled to a first battery; and a power stage circuit having a first terminal coupled to the first port and a second terminal coupled to the second port; the power stage circuit being configured to operate as a switched-capacitor converter in a first mode and as a buck converter in a second mode to charge the first battery, wherein the switched-capacitor converter and the buck converter share a portion of the power transistor.

[0006] In one embodiment, the first port is configured to couple to an external device in a second operating state; the power stage circuit is configured to operate as a switched-capacitor converter in a third mode and as a boost converter in a fourth mode, such that the first battery discharges to power the external device, wherein the switched-capacitor converter and the boost converter share a portion of the power transistor.

[0007] In one embodiment, the switched capacitor converter is configured as a series-parallel architecture switched capacitor converter, including a plurality of flying capacitors. When the switched capacitor converter operates in a first state, the plurality of flying capacitors and the first battery are connected in series; in a second state, the plurality of flying capacitors and the first battery are connected in parallel.

[0008] In one embodiment, the power stage circuit includes: a switched capacitor circuit coupled between the first port and the second port; and a first power transistor and a first inductor, connected in series and coupled between the first port and the second port; wherein the common terminal of the first power transistor and the first inductor is coupled to the switched capacitor circuit.

[0009] In one embodiment, the switched capacitor circuit and the first inductor together constitute the switched capacitor converter. The switched capacitor circuit is a series-parallel architecture switched capacitor circuit, which includes multiple flying capacitors. In a first state, the multiple flying capacitors are connected in series and coupled together; in a second state, the multiple flying capacitors are connected in parallel and coupled together.

[0010] In one embodiment, the first power transistor, the first inductor, and some of the power transistors in the switched capacitor circuit together constitute the buck converter or the boost converter.

[0011] In one embodiment, when the voltage conversion ratio of the switched capacitor circuit is N:1 or 1:N, the switched capacitor circuit includes: N-1 first structures, which are sequentially connected in parallel between the second port and the ground terminal, wherein each first structure includes at least one power transistor and a flying capacitor; and N second power transistors, which are respectively coupled between the second port and the first first structure, between two adjacent first structures, and between the (N-1)th first structure and the first port; wherein the common terminal of the first power transistor and the first inductor is coupled to the second first structure, and N is greater than 2.

[0012] In one embodiment, each first structure includes a third power transistor, a flying capacitor, and a fourth power transistor, which are connected in series between the second port and the ground terminal; wherein the common terminal of the first power transistor and the first inductor is coupled to the common terminal of the flying capacitor and the fourth power transistor in the second first structure.

[0013] In one embodiment, the first second power transistor is coupled between the second port and the flying capacitor and the fourth power transistor in the first first structure; the (i+1)th second power transistor is coupled between the common terminal of the third power transistor and the flying capacitor in the i-th first structure and the flying capacitor and the fourth power transistor in the (i+1)th first structure, where i is less than N-1; the Nth second power transistor is coupled between the common terminal of the third power transistor and the flying capacitor in the N-1th first structure and the first port.

[0014] In one embodiment, the first power transistor, the first inductor, and the fourth power transistor in the second first structure together constitute the buck converter or the boost converter.

[0015] In one embodiment, in either the first or third mode, the control signals for the third and fourth power transistors are the same, the duty cycles for the control signals for the second and third power transistors are the same, and the phase difference is 180°, so that the power stage circuit operates as a switched capacitor converter to charge the first battery or supply power to the external device.

[0016] In one embodiment, in a second mode, the first power transistor and the fourth power transistor in the second first structure are complementaryly turned on, causing the power stage circuit to operate as a buck converter to charge the first battery.

[0017] In one embodiment, in a fourth mode, the first power transistor and the fourth power transistor in the second first structure are complementaryly turned on, so that the power stage circuit operates as a boost converter to power the external device.

[0018] In one embodiment, the charging circuit further includes a control circuit configured to control the operating mode of the power stage circuit based on the output current and / or output voltage of the power stage circuit.

[0019] In one embodiment, under a first operating condition, the first port is coupled to a first voltage source, and the output current is equal to the charging current. When the output current is greater than a first threshold, the power stage circuit is controlled to operate in a first mode, functioning as a switched capacitor converter. When the output current is less than the first threshold, the power stage circuit is controlled to operate in a second mode, functioning as a buck converter.

[0020] In one embodiment, under the second operating condition, the first port is coupled to an external device. When the output current is greater than a second threshold, the power stage circuit is controlled to operate in a third mode, functioning as a switched capacitor converter. When the charging current is less than the second threshold, the power stage circuit is controlled to operate in a fourth mode, functioning as a boost converter.

[0021] In one embodiment, when the power stage circuit operates as a switched capacitor converter, the output voltage of the first voltage source is adjusted according to the voltage of the first battery; when the power stage circuit operates as a buck converter, the output voltage of the first voltage source is controlled to a fixed value.

[0022] In one embodiment, when the first battery is being charged at a constant current, the power stage circuit is controlled to operate in a first mode, functioning as a switched capacitor converter; when the first battery is being charged at a constant voltage and the charging current is greater than a first threshold, the power stage circuit is controlled to operate in the first mode, functioning as a switched capacitor converter; when the first battery is being charged at a constant voltage and the charging current is less than the first threshold, the power stage circuit is controlled to operate in a second mode, functioning as a buck converter.

[0023] Compared with existing technologies, the technical solution of the present invention has the following advantages: The charging circuit of the present invention includes a first port configured to be coupled to a first voltage source in a first operating state; a second port configured to be coupled to a first battery; and a power stage circuit configured to operate as a switched-capacitor converter in a first mode and as a buck converter in a second mode to charge the first battery, wherein the switched-capacitor converter and the buck converter share some power transistors. Compared with traditional fast charging solutions, the charging circuit of the present invention requires only one circuit to operate in both switched-capacitor and buck converter forms, and has fewer switching transistors, improving the system integration and power density, and is simpler to control and lower in cost. Attached Figure Description

[0024] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0025] Figure 1 This is a circuit diagram of a first embodiment of the charging circuit of the present invention;

[0026] Figure 2 This is a waveform diagram of the control signal embodiment of the charging circuit of the present invention in the first mode.

[0027] Figures 3a-3bThis is a schematic diagram of the working circuit in each working zone under the first mode of the charging circuit embodiment one of the present invention;

[0028] Figure 4 This is a circuit diagram of a second embodiment of the charging circuit of the present invention. Detailed Implementation

[0029] The present invention is described below based on embodiments, but the invention is not limited to these embodiments. In the detailed description of the invention below, certain specific details are described in detail. Those skilled in the art will fully understand the invention even without these details. To avoid obscuring the essence of the invention, well-known methods, processes, flows, elements, and circuits are not described in detail.

[0030] Furthermore, those skilled in the art should understand that the accompanying drawings provided herein are for illustrative purposes only and are not necessarily drawn to scale.

[0031] Furthermore, it should be understood that in the following description, "circuit" refers to a conductive loop consisting of at least one element or sub-circuit connected by electrical or electromagnetic connections. When an element or circuit is said to be "connected" to another element or "connected" between two nodes, it can be directly coupled or connected to another element, or there may be intermediate elements. The connection between elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected" to another element, it means that there are no intermediate elements between them.

[0032] Unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as encompassing rather than being exclusive or exhaustive; that is, meaning "including but not limited to."

[0033] In the description of this invention, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0034] Figure 1 This is a circuit diagram of a first embodiment of the charging circuit of the present invention; the charging circuit includes a first port o1, a second port o2, and a power stage circuit; the first port o1 is coupled to a first voltage source V. BUSThe second port o2 is coupled to the first battery B1. The first terminal of the power stage circuit is coupled to the first port o1, and the second terminal of the power stage circuit is coupled to the second port o2. The power stage circuit is configured to operate as a switched-capacitor converter in a first mode and as a buck converter in a second mode to charge the first battery B1. The switched-capacitor converter and the buck converter share some power transistors. In this embodiment, the switched-capacitor converter is configured as a series-parallel architecture switched-capacitor converter.

[0035] In this embodiment, the first terminal of the power stage circuit is the input terminal, and the second terminal of the power stage circuit is the output terminal.

[0036] Specifically, the power stage circuit includes: a switched capacitor circuit 1, a first power transistor Q1, and a first inductor L. The switched capacitor circuit 1 is configured as a series-parallel switched capacitor circuit and is coupled between the first port o1 and the second port o2. The first power transistor Q1 and the first inductor L are connected in series between the first port o1 and the second port o2, wherein the common terminal SW of the first power transistor Q1 and the first inductor L is coupled to the switched capacitor circuit 1.

[0037] The switched capacitor circuit 1 and the first inductor L together constitute the switched capacitor converter. The first power transistor Q1, the first inductor L, and some of the power transistors in the switched capacitor circuit 1 together constitute the buck converter. In this embodiment, the switched capacitor circuit 1 is configured as a series-parallel switched capacitor circuit, and the voltage conversion ratio between the input and output terminals is 4:1.

[0038] The switched capacitor circuit 1 includes: three first structures 11-13 and four second power transistors 21-24. The three first structures 11-13 are connected in parallel between the second port o2 and the ground terminal. Each first structure includes at least one power transistor and a flying capacitor. The four second power transistors 21-24 are respectively coupled between the second port o2 and the first first structure 11, between the first first structure 11 and the second first structure 12, between the second first structure 12 and the third first structure 13, and between the third first structure 13 and the first port o1. The common terminal SW of the first power transistor Q1 and the first inductor L is coupled to the second first structure 12.

[0039] The first structure 11 includes a third power transistor 31 and a flying capacitor C. FIY1 The third power transistor 32 and the fourth power transistor 41 are connected in series between the second port o2 and the ground terminal; the first structure 12 includes the third power transistor 32 and the flying capacitor C. FIY2The third power transistor 33 and the fourth power transistor 42 are connected in series between the second port o2 and the ground terminal; the first structure 13 includes the third power transistor 33 and the flying capacitor C. FIY3 The fourth power transistor 43 is connected in series between the second port o2 and the ground terminal. The second power transistor 21 is coupled between the second port o2 and the flying capacitor C in the first structure 11. FIY1 Between the common terminal of the second power transistor 22 and the third power transistor Q31 in the first structure 11 and the flying capacitor C. FIY1 The common terminal and the flying capacitor C of the first structure 12 FIY2 The second power transistor 23 is coupled between the common terminal of the fourth power transistor Q42 and the third power transistor Q32 in the first structure 12 and the flying capacitor C. FIY2 The common terminal and the flying capacitor C of the first structure 13 FIY3 The second power transistor 24 is coupled between the common terminal of the third power transistor Q33 in the first structure 13 and the flying capacitor C. FIY3 The common terminal of the first power transistor Q1 and the first inductor L is connected to the first port o1. Furthermore, the common terminal SW of the first power transistor Q1 and the first inductor L is connected to the flying capacitor C in the first structure 12. FIY2 It is coupled to the common terminal of the fourth power transistor Q42.

[0040] Optionally, the charging circuit further includes a first switching transistor S1 (i.e., a BATFET), coupled between the first inductor L and the second port O2, for path management to control whether the first battery is charged. The voltage at the common terminal of the first inductor L and the first switching transistor S1 is the output voltage V of the power stage circuit. SYS This is to provide power to the system.

[0041] Optionally, the charging circuit further includes a second switching transistor QB for leakage protection, to prevent current from flowing back into the first voltage source V. BUS .

[0042] In this embodiment, the charging circuit further includes an input capacitor Cin and an output voltage Co, to respectively charge the first voltage source V. BUS Output voltage and power stage circuit output voltage V SYS Perform filtering.

[0043] In this embodiment, the switched capacitor circuit 1 is configured as a series-parallel switched capacitor circuit, and the voltage conversion ratio between the input and output terminals is 4:1. In other embodiments, the switched capacitor circuit 1 is a switched capacitor circuit with other voltage conversion ratios (such as 3:1, 5:1), and the present invention does not limit this.

[0044] In this invention, the charging circuit further includes a control circuit ( Figure 1 (Not shown), the control circuit is configured to control the operating mode of the power stage circuit based on the output current and / or output voltage. In this embodiment, the output current is equal to the charging current. During the charging process, the operating mode of the power stage circuit can be controlled according to the user's charging needs. For example, in this embodiment, when the output current is greater than a first threshold, the power stage circuit is controlled to operate in a first mode, functioning as a switched-capacitor converter; when the output current is less than the first threshold, the power stage circuit is controlled to operate in a second mode, functioning as a buck converter. More specifically, when the first battery is undergoing constant current charging, the power stage circuit is controlled to operate in the first mode, functioning as a switched-capacitor converter; when the first battery is undergoing constant voltage charging and the charging current is greater than the first threshold, the power stage circuit is controlled to operate in the first mode, functioning as a switched-capacitor converter; when the first battery is undergoing constant voltage charging and the charging current is less than the first threshold, the power stage circuit is controlled to operate in the second mode, functioning as a buck converter. The above provides an example of the power stage circuit operating mode control of the present invention, but the present invention does not limit this.

[0045] In this embodiment, when the power stage circuit operates in the first mode, it functions as a switched-capacitor converter: the first power transistor Q1 is turned off.

[0046] The control signals for the second power transistors Q21-Q24 are the same, GH. The control signals for the third power transistors Q31-Q33 and the fourth power transistors Q41-Q43 are the same, GL. The duty cycles of control signals GH and GL are the same, and their phase difference is 180°. It will be understood by those skilled in the art that the control signals GH and GL for the power transistors in this invention have a dead time to avoid the simultaneous conduction of complementary power transistors. Subsequent descriptions of complementary conduction also involve dead times and will not be elaborated further. Figure 2 This is a waveform diagram of the control signal in the first mode of the charging circuit embodiment of the present invention. The intervals t1-t2 and t3-t4 are dead zones.

[0047] During the t0-t1 and t4-t5 intervals (when the switched capacitor converter operates in its first state), GH is high and GL is low. The second power transistors Q21-Q24 are turned on, while the third power transistors Q31-Q33 and the fourth power transistors Q41-Q43 are turned off. The schematic diagram of the power stage circuit at this time is shown below. Figure 3a As shown, the flying capacitor C FIY1 ~C FIY3 Connected in series with the first battery B1, the first voltage source VBUS For flying capacitor C FIY1 ~C FIY3 The first battery B1 is charged, thereby the first voltage source V BUS Equal to three flying capacitors C FIY1 ~C FIY3 The voltage VC on FIY1 ~VC FIY3 The sum of the voltages on the first battery and the voltage VBAT, i.e.: V BUS =VC FLY1 +VC FLY2 +VC FLY3 +VBAT; and at this time, the voltage V at the common terminal SW. SW It equals the voltage VBAT of the first battery and the flying capacitor C. FIY1 The sum, i.e., VSW = VC FLY1 +VBAT = 2VBAT;

[0048] During the t2-t3 interval (when the switched capacitor converter operates in the second state), GH is low and GL is high. The third power transistors Q31-Q33 and the fourth power transistors Q41-Q43 are turned on, while the second power transistors Q21-Q24 are turned off. The schematic diagram of the power stage circuit at this time is shown below. Figure 3b As shown, the flying capacitor C FIY1 ~C FIY3 Each of the three flying capacitors C is connected in parallel with the first battery B1, thus forming a series of flying capacitors C. FIY1 ~C FIY3 The voltage VC on FIY1 ~VC FIY3 The voltage VBAT on the first battery is equal to the voltage VC. FLY1 =VC FLY2 =VC FLY3 =VBAT. At this time, the voltage V at the common terminal SW is... SW Equal to zero, that is, V SW =0.

[0049] Therefore, the voltage VBAT of the first battery is equal to the input voltage V of the power stage circuit. BUS One-quarter, that is, VBAT = 1 / 4V BUS .

[0050] Furthermore, since the duty cycles of both control signals GL and GH are 50%, the output voltage V of the power stage circuit can be obtained. SYS Equal to 2VBAT * 50%, thus the output voltage V of the power stage circuit SYS It equals the voltage VBAT of the first battery, i.e., V. SYS =VBAT.

[0051] In conclusion, VBAT = V SYS =1 / 4V BUS .

[0052] In the first mode, the power stage circuit operates as a switched-capacitor converter with an input-to-output voltage conversion ratio of 4:1 to charge the first battery. The switched-capacitor circuit 1 and the first inductor L together constitute the switched-capacitor converter. Furthermore, when operating in the first mode, the power stage circuit adjusts the output voltage of the first voltage source according to the voltage of the first battery.

[0053] exist Figure 2 In this embodiment, the duty cycle of both control signal GL and control signal GH is 50%, and this invention does not impose any limitation on this. Furthermore, any method of controlling the switched capacitor converter is applicable here, and this invention does not impose any limitation on this.

[0054] This embodiment provides a structure for a switched capacitor circuit 1, but the present invention does not limit it. As long as the switched capacitor circuit 1 is a series-parallel architecture switched capacitor circuit, that is, the switched capacitor circuit 1 includes multiple flying capacitors, which are connected in series in the first state and in parallel in the second state, it is within the protection scope of the present invention.

[0055] In this embodiment, when the power stage circuit operates in the second mode, it functions as a buck converter: the second power transistors Q21-Q24 are turned off, the third power transistors Q31-Q33 are turned off, and the second power transistors Q41 and Q43 are turned off.

[0056] The first power transistor Q1 and the fourth power transistor Q42 are controlled to conduct complementaryly, causing the power stage circuit to operate as a buck converter to charge the first battery. The first power transistor Q1, the first inductor L, and the fourth power transistor Q42 together constitute the buck converter. In this embodiment, the output voltage of the buck converter is adjusted by controlling the duty cycle or frequency of the control signals of the first power transistor Q1 and the fourth power transistor Q42. Furthermore, when the power stage circuit operates in the second mode, the output voltage of the first voltage source is controlled to be a fixed value.

[0057] It should be noted that any control method for adjusting the output voltage of the buck converter is applicable here, and this invention does not impose any restrictions on it.

[0058] In this embodiment, the charging circuit of the present invention only requires one circuit to operate in both switched capacitor converter and buck converter forms. The switched capacitor converter and the buck converter share a power transistor, namely the fourth power transistor Q42, and can also share a first switching transistor QB. With fewer switching transistors, the system integration and power density are improved, and the control is simpler and the cost is lower.

[0059] In this embodiment, the first port o1 is coupled to the first voltage source V. BUS However, in other embodiments, when the first battery B1 has a high charge level or is fully charged, the first port O1 is coupled to an external device. In this case, the first terminal of the power stage circuit is the output terminal, and the second terminal is the input terminal. The first battery discharges to power the external device. The control circuit is configured to control the operating mode of the power stage circuit based on the output current and / or output voltage. For example, when the output current is greater than a second threshold, the power stage circuit is controlled to operate in a third mode, functioning as a switched-capacitor converter; when the output current is less than the second threshold, the power stage circuit is controlled to operate in a fourth mode, functioning as a boost converter, where the switched-capacitor converter and the boost converter share some power transistors.

[0060] The power stage circuit is configured to operate as a switched-capacitor converter in the third mode. The switched-capacitor circuit 1 and the first inductor L together constitute the switched-capacitor converter. In this mode, the voltage conversion ratio between the input and output terminals of the switched-capacitor circuit 1 is 1:4, and the voltage conversion ratio between the input and output terminals of the switched-capacitor converter is also 1:4. In the third mode, the switching states and control methods of the power transistors in the power stage circuit are the same as in the first mode, and will not be described again here.

[0061] In the fourth mode, it operates as a boost converter, with the first power transistor Q1, the first inductor L, and the fourth power transistor Q42 together forming the boost converter. In the fourth mode, the switching states and control methods of each power transistor in the power stage circuit are the same as in the second mode, and will not be described again here.

[0062] Figure 4This is a circuit diagram of a second embodiment of the charging circuit of the present invention. The difference between this embodiment and the first embodiment is that the switched capacitor circuit 1 is configured as a series-parallel architecture switched capacitor circuit. When the first port is coupled to the first voltage source, the voltage conversion ratio of the switched capacitor circuit is N:1, and thus the voltage conversion ratio of the switched capacitor converter is N:1. Or when the first port is coupled to an external device, the voltage conversion ratio of the switched capacitor circuit is 1:N, and thus the voltage conversion ratio of the switched capacitor converter is 1:N, where N is greater than 2.

[0063] Specifically, the switched capacitor circuit 1 includes: N-1 first structures 11 to 1(N-1) and N second power transistors Q21 to Q2N. The first structures 11 to 1(N-1) are connected in parallel between the second port o2 and the ground terminal. Each first structure includes at least one power transistor and a flying capacitor. The N second power transistors Q21 to Q2N are respectively used to couple the second port o2 to the first first structure 11, between two adjacent first structures 11 to 1(N-1), and between the (N-1)th first structure 1(N-1) and the first port o1. The common terminal SW of the first power transistor Q1 and the first inductor L is coupled to the second first structure, and N is greater than 2.

[0064] Each first structure 1k includes a third power transistor Q3k and a flying capacitor C. FIYk The fourth power transistor Q4k is connected in series between the second port o2 and the ground terminal, where k is less than N; the first second power transistor Q21 is coupled between the second port o2 and the flying capacitor C of the first first structure 11. FIY1 Between the second power transistor Q41 and the fourth power transistor Q41; the (i+1)th second power transistor Q2(i+1) is used to couple the third power transistor Q3i of the i-th first structure 1i and the flying capacitor C. FIYi The common terminal and the flying capacitor C of the (i+1)th first structure 1 (i+1) FIY(i+1) Between the common terminal of the fourth power transistor Q4(i+1) and the Nth second power transistor Q2N, i is less than N-1; the Nth second power transistor Q2N is coupled to the third power transistor Q3(N-1) of the N-1th first structure 1(N-1) and the flying capacitor C. FIY(N-1) The common terminal of the first power transistor Q1 and the first inductor L is connected to the first port o1. Specifically, the common terminal SW of the first power transistor Q1 and the first inductor L is connected to the flying capacitor C in the second first structure 12. FIY2 It is coupled to the common terminal of the fourth power transistor Q42.

[0065] The remaining parts of Embodiment 2, such as working conditions, working modes, and control methods, are similar to those of Embodiment 1 and will not be described in detail here.

[0066] Although the embodiments are described and illustrated separately above, some common technologies are involved. Those skilled in the art can replace and integrate them between the embodiments. If there is any content not explicitly described in one embodiment, then another embodiment that is described can be referred to.

[0067] As described above, these embodiments of the present invention do not exhaustively cover all details, nor do they limit the invention to the specific embodiments described. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A charging circuit, characterized in that, include: The first port is configured to be coupled to a first voltage source in a first operating condition. The second port is configured to be coupled to the first battery; and A power stage circuit, wherein a first terminal is coupled to the first port and a second terminal is coupled to the second port; The power stage circuit includes: a switched capacitor circuit coupled between the first port and the second port; and a first power transistor and a first inductor, connected in series and coupled between the first port and the second port; wherein the common terminal of the first power transistor and the first inductor is coupled to the switched capacitor circuit. The power stage circuit is configured such that, in a first mode, the switched capacitor circuit and the first inductor together constitute a switched capacitor converter and operate as a switched capacitor converter; and in a second mode, the first power transistor, the first inductor, and a portion of the power transistors in the switched capacitor circuit together constitute a buck converter and operate as a buck converter to charge the first battery.

2. The charging circuit according to claim 1, characterized in that: The first port is configured to couple to an external device in a second operating state; The power stage circuit is configured to operate as a switched-capacitor converter in a third mode and as a boost converter in a fourth mode, such that the first battery discharges to power the external device, wherein the switched-capacitor converter and the boost converter share some power transistors.

3. The charging circuit according to claim 1 or 2, characterized in that: The switched capacitor converter is configured as a series-parallel architecture switched capacitor converter, including multiple flying capacitors. When the switched capacitor converter operates in a first state, the multiple flying capacitors are connected in series with the first battery; in a second state, the multiple flying capacitors are connected in parallel with the first battery respectively.

4. The charging circuit according to claim 1 or 2, characterized in that: The power stage circuit includes: A switched capacitor circuit is coupled between the first port and the second port; and The first power transistor and the first inductor are connected in series and then coupled between the first port and the second port; The common terminal of the first power transistor and the first inductor is coupled to the switched capacitor circuit.

5. The charging circuit according to claim 4, characterized in that: The switched capacitor circuit and the first inductor together constitute the switched capacitor converter. The switched capacitor circuit is a series-parallel architecture switched capacitor circuit, which includes multiple flying capacitors. In the first state, the multiple flying capacitors are connected in series and coupled together; in the second state, the multiple flying capacitors are connected in parallel and coupled together.

6. The charging circuit according to claim 4, characterized in that: The first power transistor, the first inductor, and some of the power transistors in the switched capacitor circuit together constitute the buck converter or the boost converter.

7. The charging circuit according to claim 4, characterized in that: When the voltage conversion ratio of the switched capacitor circuit is N:1 or 1:N, the switched capacitor circuit includes: N-1 first structures are connected in parallel between the second port and the ground terminal, wherein each first structure includes at least one power transistor and a flying capacitor; and N second power transistors are respectively coupled between the second port and the first first structure, between two adjacent first structures, and between the (N-1)th first structure and the first port; In this configuration, the common terminal of the first power transistor and the first inductor is coupled to the second first structure, and N is greater than 2.

8. The charging circuit according to claim 7, characterized in that: Each first structure includes a third power transistor, a flying capacitor, and a fourth power transistor, which are connected in series between the second port and the ground terminal. The common terminal of the first power transistor and the first inductor is coupled to the common terminal of the flying capacitor and the fourth power transistor in the second first structure.

9. The charging circuit according to claim 8, characterized in that: The first second power transistor is coupled between the second port and the flying capacitor and the fourth power transistor in the first first structure; The (i+1)th second power transistor is used to couple between the common terminal of the third power transistor and the flying capacitor in the i-th first structure and the flying capacitor and the fourth power transistor in the (i+1)-th first structure, where i is less than N-1; The Nth second power transistor is coupled between the common terminal of the third power transistor and the flying capacitor in the (N-1)th first structure and the first port.

10. The charging circuit according to claim 8, characterized in that: The first power transistor, the first inductor, and the fourth power transistor in the second first structure together constitute the buck converter or the boost converter.

11. The charging circuit according to claim 8, characterized in that: In either the first or third mode, the control signals for the third and fourth power transistors are the same, the duty cycles for the control signals for the second and third power transistors are the same, and the phase difference is 180°, so that the power stage circuit operates as a switched capacitor converter to charge the first battery or supply power to the external device.

12. The charging circuit according to claim 8, characterized in that: In the second mode, the first power transistor and the fourth power transistor in the second first structure are complementaryly turned on, so that the power stage circuit operates as a buck converter to charge the first battery.

13. The charging circuit according to claim 8, characterized in that: In the fourth mode, the first power transistor and the fourth power transistor in the second first structure are complementaryly turned on, so that the power stage circuit operates as a boost converter to power the external device.

14. The charging circuit according to claim 1 or 2, characterized in that: The charging circuit also includes a control circuit configured to control the operating mode of the power stage circuit based on the output current and / or output voltage of the power stage circuit.

15. The charging circuit according to claim 14, characterized in that: In the first operating condition, the first port is coupled to the first voltage source, and the output current is equal to the charging current. When the output current is greater than the first threshold, the power stage circuit is controlled to operate in the first mode, in the form of a switched capacitor converter. When the output current is less than the first threshold, the power stage circuit is controlled to operate in the second mode, functioning as a buck converter.

16. The charging circuit according to claim 14, characterized in that: In the second operating state, the first port is coupled to an external device. When the output current is greater than the second threshold, the power stage circuit is controlled to operate in the third mode, in the form of a switched capacitor converter. When the output current is less than the second threshold, the power stage circuit is controlled to operate in the fourth mode, functioning as a boost converter.

17. The charging circuit according to claim 1, characterized in that: When the power stage circuit operates as a switched capacitor converter, the output voltage of the first voltage source is adjusted according to the voltage of the first battery. When the power stage circuit operates as a buck converter, the output voltage of the first voltage source is controlled to a fixed value.

18. The charging circuit according to claim 1, characterized in that: When the first battery is being charged at a constant current, the power stage circuit is controlled to operate in the first mode, in the form of a switched capacitor converter. When the first battery is charged under constant voltage and the charging current is greater than the first threshold, the power stage circuit is controlled to work in the first mode, in the form of a switched capacitor converter. When the first battery is charged under constant voltage and the charging current is less than the first threshold, the power stage circuit is controlled to operate in the second mode, working as a buck converter.

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