Switching converter, switching circuit and control method thereof

Abstract

The application discloses a switching converter, a switching circuit and a control method thereof. The switching circuit comprises a first switch tube, a second switch tube, a third switch tube, a fourth switch tube and a fifth switch tube. The first end of the first switch tube is coupled to the input end of the switching converter. The first end of the second switch tube is coupled to the second end of the first switch tube through a first energy storage element. The first end of the third switch tube is coupled to the second end of the first switch tube. The first end of the fourth switch tube is coupled to the second end of the third switch tube, and the second end of the fourth switch tube is coupled to the second end of the second switch tube. The first end of the fifth switch tube is coupled to the second end of the third switch tube, and the second end of the fifth switch tube is coupled to the second end of the second switch tube through a second energy storage element. The first end of the second switch tube is coupled to the output end through an energy storage circuit, and the second end of the third switch tube and the first end of the fourth switch tube are coupled to the output end through the energy storage circuit.

Description

Technical Field

[0001] This invention relates to an electronic circuit, and more specifically, to a switching converter, its switching circuit, and a control method thereof. Background Technology

[0002] With the development of the computer and electronics industries, the requirements for the efficiency, output ripple, and load dynamic performance of switching converters are becoming increasingly stringent. Traditional single-phase switching converters can no longer meet these requirements. Therefore, it is necessary to design new switching converter topologies to simultaneously satisfy these requirements. Summary of the Invention

[0003] Therefore, the purpose of this invention is to solve the above-mentioned technical problems of the prior art and to propose a switching converter, its switching circuit and control method.

[0004] According to an embodiment of the present invention, a switching circuit for a switching converter is provided, the switching converter having an input terminal for receiving an input voltage and an output terminal for providing an output voltage, the switching circuit comprising: a first switching transistor having a first terminal and a second terminal, the first terminal of the first switching transistor being coupled to the input terminal; a second switching transistor having a first terminal and a second terminal, the first terminal of the second switching transistor being coupled to the second terminal of the first switching transistor via a first energy storage element; and a third switching transistor having a first terminal and a second terminal, the first terminal of the third switching transistor being coupled to the second terminal of the first switching transistor, and coupled to the first terminal of the second switching transistor via the first energy storage element; The system comprises four switching transistors, each having a first terminal and a second terminal. The first terminal of the fourth switching transistor is coupled to the second terminal of the third switching transistor, and the second terminal of the fourth switching transistor is coupled to the second terminal of the second switching transistor. A fifth switching transistor also comprises a first terminal and a second terminal. The first terminal of the fifth switching transistor is coupled to the second terminals of the third and fourth switching transistors, and the second terminal of the fifth switching transistor is coupled to the second terminals of the second and fourth switching transistors via a second energy storage element. The first terminal of the second switching transistor is coupled to an output terminal via an energy storage circuit, and the second terminals of the third and fourth switching transistors are coupled to an output terminal via an energy storage circuit.

[0005] According to an embodiment of the present invention, a switching converter is also provided, having an input terminal for receiving an input voltage and an output terminal for providing an output voltage, the switching converter comprising: an energy storage circuit; and the aforementioned switching circuit.

[0006] According to an embodiment of the present invention, a control method for a switching converter is also proposed, the switching converter having an input terminal for receiving an input voltage and an output terminal for providing an output voltage. The control method includes: coupling the input terminal of the switching converter through a first terminal of a first switching transistor; coupling the first terminal of a second switching transistor to a second terminal of the first switching transistor; coupling the first terminal of a third switching transistor to the second terminal of the first switching transistor and the first terminal of the second switching transistor; coupling the first terminal of a fourth switching transistor to the second terminal of the third switching transistor and the second terminal of the fourth switching transistor to the second terminal of the second switching transistor; coupling the first terminal of a fifth switching transistor to the second terminals of the third and fourth switching transistors and the second terminal of the fifth switching transistor to the second terminals of the second and fourth switching transistors; wherein the first terminal of the second switching transistor is coupled to the output terminal through an energy storage circuit, and the second terminals of the third and fourth switching transistors are coupled to the output terminal through an energy storage circuit.

[0007] The switching converter according to embodiments of the present invention has higher efficiency, better load dynamic performance, lower output ripple, and a larger duty cycle. Attached Figure Description

[0008] To better understand this invention, it will be described in detail with reference to the following drawings:

[0009] Figure 1 This is a circuit diagram of a switching converter 100 according to an embodiment of the present invention;

[0010] Figure 2 This is a circuit diagram of a switching converter 200 according to an embodiment of the present invention;

[0011] Figure 3 This is a circuit diagram 200A showing the switching circuit 10 in operating state S1 according to an embodiment of the present invention;

[0012] Figure 4 This is a circuit diagram 200B showing the switching circuit 10 in operating state S2 according to an embodiment of the present invention;

[0013] Figure 5 This is a circuit diagram 200C showing the switching circuit 10 in operating state S3 according to an embodiment of the present invention;

[0014] Figure 6 This is a circuit diagram 200D showing the switching circuit 10 in operating state S4 according to an embodiment of the present invention;

[0015] Figure 7 This is a circuit diagram 200E showing the switching circuit 10 in operating state S5 according to an embodiment of the present invention;

[0016] Figure 8 This is a circuit diagram 200F showing the switching circuit 10 in operation state S6 according to an embodiment of the present invention;

[0017] Figure 9 This is a circuit diagram 200G showing the switching circuit 10 in operation state S7 according to an embodiment of the present invention;

[0018] Figure 10 This is a circuit diagram 200H showing the switching circuit 10 in operating state S8 according to an embodiment of the present invention;

[0019] Figure 11 This is a flowchart of a control method 1100 for a switching converter according to an embodiment of the present invention.

[0020] In the accompanying drawings, the same or corresponding reference numerals are used to denote the same or corresponding elements. Detailed Implementation

[0021] Specific embodiments of the present invention will now be described in detail. It should be noted that the embodiments described herein are for illustrative purposes only and are not intended to limit the invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other instances, well-known circuits, materials, or methods have not been specifically described to avoid obscuring the invention.

[0022] Throughout this specification, references to “an embodiment,” “an example,” or “an example” mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases “in an embodiment,” “in an embodiment,” “an example,” or “an example” appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the accompanying drawings provided herein are for illustrative purposes and are not necessarily drawn to scale. It should be understood that when an element is referred to as “coupled to” or “connected to” another element, it can be directly coupled to or coupled to the other element, or there may be intermediate elements. Conversely, when an element is referred to as “directly coupled to” or “directly connected to” another element, there are no intermediate elements. The same reference numerals indicate the same elements. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0023] Figure 1This is a circuit diagram of a switching converter 100 according to an embodiment of the present invention. The switching converter 100 has an input terminal 101 that receives an input voltage VIN and an output terminal 102 that provides an output voltage VO. Figure 1 In the illustrated embodiment, the switching converter 100 includes switching transistors Q1A, Q1B, Q2A, Q2B, and Q3. The switching transistors Q1A, Q1B, Q2A, Q2B, and Q3 can be any suitable power device, such as a metal-oxide-semiconductor field-effect transistor (MOSFET), a junction field-effect transistor (JFET), or an insulated gate bipolar transistor (IGBT).

[0024] The switching converter 100 converts the input voltage VIN to the output voltage VO by turning on and off switching transistors Q1A, Q1B, Q2A, Q2B, and Q3. Switch Q1A has a first terminal 111 and a second terminal 112, with the first terminal 111 coupled to the input terminal 101. Switch Q1B has a first terminal and a second terminal; the first terminal 113 of switch Q1B is coupled to the second terminal 112 of switch Q1A via an energy storage element 11, and the second terminal 114 of switch Q1B is coupled to a reference ground. In one embodiment, the energy storage element 11 includes, for example, an inductor or a capacitor. Switch Q2A has a first terminal 115 and a second terminal 116, with the first terminal 115 coupled to the second terminal 112 of switch Q1A. Switch Q2B has a first terminal 117 and a second terminal 118. The first terminal 117 of switch Q2B is coupled to the second terminal 116 of switch Q2A, and the second terminal 118 of switch Q2B is coupled to the second terminal 114 of switch Q1B, i.e., coupled to reference ground. Switch Q3 has a first terminal 119 and a second terminal 120. The first terminal 119 of switch Q3 is coupled to the second terminal 116 of switch Q2A, and the second terminal 120 of switch Q3 is coupled to the second terminals 114 and 118 of switch Q1B via an energy storage element 12, i.e., coupled to reference ground. In one embodiment, the energy storage element 12 includes, for example, an inductor or a capacitor. In one embodiment, the first terminal 113 of switch Q1B is coupled to the output terminal 102 via an energy storage circuit 20, and the second terminals 116 of switch Q2A and 117 of switch Q2B are coupled to the output terminal 102 via the energy storage circuit 20. In one embodiment, the energy storage circuit 20 includes, for example, an inductor or a capacitor.

[0025] Figure 2This is a circuit diagram of a switching converter 200 according to an embodiment of the present invention. Figure 2 In the illustrated embodiment, energy storage elements 11 and 12 are described using capacitors as an example. Those skilled in the art will understand that energy storage elements 11 and 12 can also be inductors or other suitable energy storage elements. Figure 2 In the illustrated embodiment, the energy storage circuit 20 further includes inductors L1 and L2. The second terminal 116 of switch Q2A, the first terminal 117 of switch Q2B, and the first terminal 119 of switch Q3 are coupled to the output terminal 102 via inductor L1. The first terminal 113 of switch Q1B is coupled to the output terminal 102 via inductor L2. In one embodiment, the energy storage circuit 20 further includes an output capacitor CO, coupled between the output terminal 102 and reference ground.

[0026] During normal operation of the switching converter 200, the voltages across capacitors 11 and 12 are both half of the input voltage VIN (0.5VIN). The voltage stress on switching transistors Q1A, Q1B, Q2A, Q2B, and Q3 during turn-on and turn-off is also half of the input voltage VIN. Therefore, the switching losses of the switching converter 200 are reduced. Furthermore, the reduction in voltage stress also reduces the cost of the switching transistors, thereby reducing the overall cost of the switching converter 200.

[0027] The switching circuit 10 may include, for example, but not limited to, the following: Figures 3-7 The five different operating states S1 to S5 are shown to transmit power.

[0028] Figure 3 This is a circuit diagram 200A showing the switching circuit 10 in operating state S1 according to an embodiment of the present invention. When the switching circuit 10 is in operating state S1, switching transistors Q1A and Q2B remain on, while switching transistors Q1B, Q2A, and Q3 remain off. The voltage across inductor L1 is -VO, and the slope of the current I1 flowing through inductor L1 is -VO / L1. Current I2 flows from input terminal 101 through switching transistor Q1A and inductor L2, supplying power to capacitor CO and the load, and flows back to input terminal 101 via reference ground. The voltage across inductor L2 is 0.5VIN-VO, and the slope of the current I2 flowing through inductor L2 is (0.5VIN-VO) / L2.

[0029] Figure 4This is a circuit diagram 200B showing the switching circuit 10 in operating state S2 according to an embodiment of the present invention. When the switching circuit 10 is in operating state S2, switching transistors Q1B, Q2A, and Q3 remain on, while switching transistors Q1A and Q2B remain off. The voltage across inductor L1 is 0.5VIN-VO, and the slope of the current I1 flowing through inductor L1 is (0.5VIN-VO) / L1. The voltage across inductor L2 is -VO, and the slope of the current I2 flowing through inductor L2 is -VO / L2. Capacitor 11 charges capacitor 12 with a current Ichr. In one embodiment, a pre-charging circuit can be used to reduce the current Ichr. In another embodiment, the current Ichr can be reduced by delaying the turn-on of switching transistor Q3. Ideally, the voltage across capacitor 12 eventually equals the voltage across capacitor 11.

[0030] Figure 5 The circuit diagram 200C shows the switching circuit 10 in operating state S3 according to an embodiment of the present invention. When the switching circuit 10 is in operating state S3, switching transistors Q1B and Q2A remain on, while switching transistors Q1A, Q2B, and Q3 remain off. The voltage across inductor L1 is 0.5VIN-VO, and the slope of the current I1 flowing through inductor L1 is (0.5VIN-VO) / L1. The voltage across inductor L2 is -VO, and the slope of the current I2 flowing through inductor L2 is -VO / L2.

[0031] Figure 6 This is a circuit diagram 200D showing the switching circuit 10 in operating state S4 according to an embodiment of the present invention. When the switching circuit 10 is in operating state S4, switching transistors Q1B and Q2B remain on, while switching transistors Q1A, Q2A, and Q3 remain off. The voltage across inductor L1 is -VO, and the slope of the current I1 flowing through inductor L1 is -VO / L1. The voltage across inductor L2 is -VO, and the slope of the current I2 flowing through inductor L2 is -VO / L2.

[0032] Figure 7 The circuit diagram 200E shows the switching circuit 10 in operating state S5 according to an embodiment of the present invention. When the switching circuit 10 is in operating state S5, switching transistors Q1A and Q3 remain on, while switching transistors Q1B, Q2A, and Q2B remain off. The voltage across capacitor 12 is 0.5VIN, and the voltage across inductor L1 is (0.5VIN - VO). Therefore, the slope of the current I1 flowing through inductor L1 is (0.5VIN - VO) / L1. The voltage across inductor L2 is (0.5VIN - VO), therefore, the slope of the current I2 flowing through inductor L2 is (0.5VIN - VO) / L2.

[0033] According to an embodiment of the present invention, the maximum output voltage VO can reach 0.5VIN. Corresponding to different ranges of output voltage, the switching circuit 10 of the present invention can sequentially operate in different states. In one embodiment, when the output voltage VO ranges from 0 to 0.25VIN, the switching circuit 10 sequentially cycles through states S1, S4, S3, and S4. In another embodiment, when the output voltage VO ranges from 0.25VIN to 0.5VIN, the switching circuit 10 sequentially cycles through states S1, S5, S2, and S5. When the switching circuit 10 switches from operating state S5 to operating state S2, the charging current between capacitor 11 and capacitor 12 is relatively large. In another embodiment, when the output voltage VO ranges from 0.25VIN to 0.5VIN, the switching circuit 10 sequentially cycles through states S1, S5, S3, S2, and S5 to reduce the charging current between capacitor 11 and capacitor 12. In state S3, a pre-charging circuit can be used to balance the voltage between capacitor 11 and capacitor 12.

[0034] According to an embodiment of the present invention, capacitors C11 and C12 act as buffer capacitors to reduce the input voltage VIN to 0.5VIN. The switching converter of this embodiment can be considered as a two-phase parallel switching converter with an input voltage of 0.5VIN. Regardless of whether the output voltage VO is in the range of 0-0.25VIN or 0.25VIN-0.5VIN, the relationship between the input voltage VIN and the output voltage VO satisfies D = 2VO / VIN, where the duty cycle D represents, for example, the proportion of the conduction time of switch Q1A or switch Q2A within one switching cycle. The duty cycle of a conventional buck switching converter is VO / VIN, for example, the proportion of the conduction time of the high-side switch within one switching cycle. Therefore, the duty cycle of the switching converter of this embodiment is twice that of a conventional buck switching converter. This invention has a larger duty cycle D than conventional buck switching converters, which helps to reduce the difficulty of designing high-switching-frequency control systems.

[0035] When in discontinuous conduction mode (DCM), the switching circuit 10 may include, for example, but not limited to, the following: Figures 8-9 The operating states shown are S6 to S8.

[0036] Figure 8 The circuit diagram 200F shows the switching circuit 10 in operation state S6 according to an embodiment of the present invention. When the switching circuit 10 is in operation state S6, the switching transistor Q1A is turned on, while the switching transistors Q1B, Q2A, Q2B, and Q3 remain off. Power is transferred to the output terminal 102 through the inductor L2, and the current I1 flowing through the inductor L1 is 0A.

[0037] Figure 9 The circuit diagram 200G is shown for the switching circuit 10 in the operating state S7 according to an embodiment of the present invention. When the switching circuit 10 is in the operating state S7, the switching transistor Q2B is turned on, while the switching transistors Q1A, Q1B, Q2A, and Q3 remain turned off. The current I1 flowing through the inductor L1 gradually decreases, but is still greater than 0, and the current I2 flowing through the inductor L2 is 0.

[0038] Figure 10 The circuit diagram 200H is shown for the switching circuit 10 in the operating state S8 according to an embodiment of the present invention. When the switching circuit 10 is in the operating state S8, the switching transistor Q1B is turned on, while the switching transistors Q1A, Q2A, Q2B, and Q3 remain turned off. The current I2 flowing through the inductor L2 gradually decreases, but is still greater than 0, and the current I1 flowing through the inductor L1 is 0.

[0039] In one embodiment, when in discontinuous conduction mode, the switching circuit 10 cycles through states S6, S8, S3, S4, and S7 sequentially, with the output voltage VO ranging from 0 to 0.25VIN. Those skilled in the art will understand that the switching circuit 10 can also cycle through other suitable states.

[0040] Compared to switching converters with the same input / output specifications, the switching converter according to embodiments of the present invention exhibits higher efficiency, better load dynamics, lower output ripple, and a larger duty cycle. The higher efficiency of the switching converter according to embodiments of the present invention is due to the circuit topology reducing switching stress to half the input voltage VIN, thereby reducing switching losses. Furthermore, lower voltage-rated switching transistors can be used to reduce the cost of the switching converter. The better load dynamics and lower output ripple of the switching converter according to embodiments of the present invention are because the topology divides a switching converter with the same input / output specifications into two out-of-phase parts, effectively doubling the switching frequency. Compared to conventional switching converters, the switching converter according to embodiments of the present invention has a larger duty cycle, thus providing a longer switching on-time. The larger duty cycle reduces the design difficulty of peak current-mode controllers at higher switching frequencies.

[0041] Figure 11 The flowchart below shows a control method 1100 for a switching converter according to an embodiment of the present invention, including steps St1 to St4. The switching converter has an input terminal for receiving an input voltage and an output terminal for providing an output voltage.

[0042] In step St1, the first terminal of the first switch is coupled to the input terminal of the switching converter, the first terminal of the second switch is coupled to the second terminal of the first switch, the first terminal of the third switch is coupled to the second terminal of the first switch and the first terminal of the second switch, the first terminal of the fourth switch is coupled to the second terminal of the third switch, the second terminal of the fourth switch is coupled to the second terminal of the second switch, the first terminal of the fifth switch is coupled to the second terminal of the third switch and the first terminal of the fourth switch, and the second terminal of the fifth switch is coupled to the second terminal of the second switch and the second terminal of the fourth switch. The first terminal of the second switch is coupled to the output terminal through an energy storage circuit, and the second terminals of the third switch and the first terminals of the fourth switch are coupled to the output terminal through an energy storage circuit.

[0043] In step St2, when the output voltage is less than half of the input voltage, the switching converter cycles through states S1, S4, S3, and S4 in sequence. State S1 includes: the first and fourth switches remain on while the second, third, and fifth switches remain off. State S3 includes: the second and third switches remain on while the first, fourth, and fifth switches remain off. State S4 includes: the second and fourth switches remain on while the first, third, and fifth switches remain off.

[0044] In step St3, when the output voltage is greater than half of the input voltage, the switching converter cycles through states S1, S5, S3, S2, and S5 in sequence, or cycles through states S1, S5, S2, and S5 in sequence. State S2 includes: the second, third, and fifth switches remain on while the first and fourth switches remain off. State S5 includes: the first and fifth switches remain on while the second, third, and fourth switches remain off.

[0045] In step St4, when in discontinuous conduction mode, the switching converter cycles through states S6, S8, S3, S4, and S7 in sequence. State S6 includes the first switch being on while the second, third, fourth, and fifth switches are off. State S7 includes the third switch being on while the first, second, fourth, and fifth switches are off. State S8 includes the second switch being on while the first, third, fourth, and fifth switches are off.

[0046] It should be noted that the execution order of the steps in the flowchart above is not limited to... Figure 11 As shown, two consecutive function blocks can be executed simultaneously or in reverse order.

[0047] Although the invention has been described with reference to several exemplary embodiments, it should be understood that the terminology used is descriptive and exemplary, and not restrictive. Since the invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A switching circuit for a switching converter, the switching converter having an input terminal for receiving an input voltage and an output terminal for providing an output voltage, the switching circuit comprising: A first switching transistor has a first terminal and a second terminal, wherein the first terminal of the first switching transistor is coupled to the input terminal. The second switching transistor has a first terminal and a second terminal, and the first terminal of the second switching transistor is coupled to the second terminal of the first switching transistor through a first energy storage element. The third switching transistor has a first terminal and a second terminal, wherein the first terminal of the third switching transistor is coupled to the second terminal of the first switching transistor, and is coupled to the first terminal of the second switching transistor through a first energy storage element; A fourth switch has a first terminal and a second terminal, wherein the first terminal of the fourth switch is coupled to the second terminal of a third switch, and the second terminal of the fourth switch is coupled to the second terminal of a second switch. as well as A fifth switching transistor has a first terminal and a second terminal. The first terminal of the fifth switching transistor is coupled to the second terminal of the third switching transistor and the first terminal of the fourth switching transistor. The second terminal of the fifth switching transistor is coupled to the second terminal of the second switching transistor and the second terminal of the fourth switching transistor through a second energy storage element. in The first terminal of the second switching transistor is coupled to the output terminal through an energy storage circuit, and the second terminal of the third switching transistor and the first terminal of the fourth switching transistor are coupled to the output terminal through an energy storage circuit. The switching circuit can operate in a first operating state, a second operating state, a third operating state, and a fourth operating state; The first operating state includes: while the first and fourth switching transistors remain on, the second, third, and fifth switching transistors remain off; The second operating state includes: while the second, third, and fifth switches remain on, the first and fourth switches remain off; The third operating state includes: while the second and third switches remain on, the first, fourth, and fifth switches remain off; and The fourth operating state includes: while the second and fourth switches remain on, the first, third, and fifth switches remain off.

2. The switching circuit as claimed in claim 1, wherein the first energy storage element includes a first capacitor.

3. The switching circuit of claim 1, wherein the second energy storage element includes a second capacitor.

4. The switching circuit as described in claim 1, wherein when the output voltage is less than half of the input voltage, the switching circuit sequentially cycles through the first operating state, the fourth operating state, the third operating state, and the fourth operating state.

5. The switching circuit of claim 1, wherein the switching circuit can further operate in a fifth operating state, the fifth operating state including: While the first and fifth switches remain on, the second, third, and fourth switches remain off.

6. The switching circuit as described in claim 5, wherein when the output voltage is greater than half of the input voltage, the switching circuit sequentially cycles through the first operating state, the fifth operating state, the third operating state, the second operating state, and the fifth operating state, or sequentially cycles through the first operating state, the fifth operating state, the second operating state, and the fifth operating state.

7. The switching circuit as claimed in claim 1, further comprising a sixth operating state, a seventh operating state, and an eighth operating state, wherein the sixth operating state includes the first switch transistor remaining on while the second, third, fourth, and fifth switches transistors remaining off; the seventh operating state includes the third switch transistor remaining on while the first, second, fourth, and fifth switches transistors remaining off; and the eighth operating state includes the second switch transistor remaining on while the first, third, fourth, and fifth switches transistors remaining off.

8. The switching circuit of claim 7, wherein when in a discontinuous conduction mode, the switching circuit sequentially cycles through a sixth operating state, an eighth operating state, a third operating state, a fourth operating state, and a seventh operating state.

9. A switching converter having an input terminal for receiving an input voltage and an output terminal for providing an output voltage, the switching converter comprising: Energy storage circuit; as well as The switching circuit as described in any one of claims 1 to 8.

10. The switching converter of claim 9, wherein the energy storage circuit comprises: A first inductor has a first end and a second end, the first end of the first inductor being coupled to the first end of the fourth switching transistor, and the second end of the first inductor being coupled to the output end. as well as The second inductor has a first end and a second end, the first end of the second inductor being coupled to the first end of the second switching transistor, and the second end of the second inductor being coupled to the output terminal.

11. A control method for a switching converter, the switching converter having an input terminal for receiving an input voltage and an output terminal for providing an output voltage, the control method comprising: The first terminal of the first switching transistor is coupled to the input terminal of the switching converter. The first terminal of the second switching transistor is coupled to the second terminal of the first switching transistor. The first terminal of the third switch is coupled to the second terminal of the first switch and the first terminal of the second switch. The first terminal of the fourth switch is coupled to the second terminal of the third switch, and the second terminal of the fourth switch is coupled to the second terminal of the second switch. The first terminal of the fifth switch is coupled to the second terminal of the third switch and the first terminal of the fourth switch, and the second terminal of the fifth switch is coupled to the second terminal of the second switch and the second terminal of the fourth switch. in The first end of the second switch is coupled to the output end through an energy storage circuit, and the second end of the third switch and the first end of the fourth switch are coupled to the output end through an energy storage circuit. The switching converter can operate in a first operating state, a second operating state, and a third operating state; The first state includes: while the first and fourth switches remain on, the second, third, and fifth switches remain off; The second state includes: while the second and fourth switches remain on, the first, third, and fifth switches remain off; and The third state includes: while the second and third switches remain on, the first, fourth, and fifth switches remain off.

12. The control method of claim 11, further comprising: When the output voltage is less than half of the input voltage, the switching converter cycles through the first state, the second state, the third state, and the second state again.

13. The control method of claim 11, further comprising: When the output voltage is greater than half of the input voltage, the switching converter cycles through the first state, the fourth state, the third state, the fifth state, and the fourth state in sequence. in The fourth state includes: while the first and fifth switches remain on, the second, third, and fourth switches remain off; and The fifth state includes: while the second, third, and fifth switches remain on, the first and fourth switches remain off.

14. The control method of claim 11, further comprising: When the output voltage is greater than half of the input voltage, the switching converter cycles through the first state, the fourth state, the fifth state, and the fourth state in sequence. in The fourth state includes: while the first and fifth switches remain on, the second, third, and fourth switches remain off; and The fifth state includes: while the second, third, and fifth switches remain on, the first and fourth switches remain off.

15. The control method of claim 11, further comprising: When in discontinuous conduction mode, the switching converter cycles through the sixth, seventh, third, second and eighth states in sequence. in The sixth state includes keeping the first switch on while keeping the second, third, fourth, and fifth switches off. The seventh state includes the second switch remaining on while the first, third, fourth, and fifth switches remaining off; and The eighth state includes the third switch remaining on while the first, second, fourth, and fifth switches remaining off.

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