Power supply circuit and voltage converter

Abstract

The present application is applicable to the technical field of voltage converters, and provides a power supply circuit and a voltage converter. The power supply circuit includes a first switch module, a second switch module, a freewheeling module and an energy storage module. The first switch module is electrically connected to the second switch module, the freewheeling module and the energy storage module, respectively, and the freewheeling module is electrically connected to the second switch module and the energy storage module, respectively. When the load current is greater than a preset value and the first switch module and the second switch module are both in an off state, the energy storage module is used to release energy through the freewheeling module. When the first switch module is in an off state and the second switch module is in an on state, the energy storage module is also used to release energy through the freewheeling module and the second switch module, and the impedance of the freewheeling module is less than the impedance of the second switch module. The power supply circuit provided in the embodiment of the present application can provide a larger current to the load by adding a freewheeling module with a smaller impedance, thereby expanding the application scope of the power supply circuit.

Description

Technical Field

[0001] The present application belongs to the technical field of voltage converters, and in particular, relates to a power supply circuit and a voltage converter. Background Art

[0002] In traditional voltage converters (such as DC-DC converters), the power supply circuit is usually composed of an upper switch tube, a lower switch tube and an energy storage element. Since the duty cycle is usually low in actual applications, that is, the lower switch tube is on for a longer time than the upper switch tube, the output voltage is usually low, such as 3.3V, 5V, 12V, etc. At the same time, the input voltage is high, which may reach 48V, 72V or higher. In order to improve efficiency and reduce volume, traditional DC-DC converter designs usually use synchronous rectification technology, in which both the upper and lower switches are integrated. This design is very effective when the load current is small because it can reduce energy loss and improve overall efficiency. However, when the load current becomes larger, such as 2A / 3A / 4A or even higher, if a fully integrated solution is still used, the chip area will increase sharply, which is unacceptable in terms of cost. Therefore, synchronous rectification technology can support small output currents but cannot support large loads; asynchronous rectification technology can support large loads, but cannot reduce the use of diodes at low currents, and each has its limitations. Summary of the invention

[0003] The embodiments of the present application provide a power supply circuit and a voltage converter, which can solve the problem that the existing power supply circuit only supports a small output current and cannot support a large load, and has a limited application range.

[0004] In a first aspect, an embodiment of the present application provides a power supply circuit, including a first switch module, a second switch module, a freewheeling module and an energy storage module, wherein the first switch module is electrically connected to the second switch module, the freewheeling module and the energy storage module respectively, the freewheeling module is electrically connected to the second switch module and the energy storage module respectively, the first switch module is used to be electrically connected to a power supply, and the energy storage module is used to be electrically connected to a load;

[0005] When the load current is greater than a preset value and the first switch module and the second switch module are both in a disconnected state, the energy storage module is used to release energy through the freewheeling module; when the load current is greater than a preset value, the first switch module is in a disconnected state and the second switch module is in a conductive state, the energy storage module is also used to release energy through the freewheeling module and the second switch module, wherein the impedance of the freewheeling module is less than the impedance of the second switch module.

[0006] In a possible implementation of the first aspect, the first switch module includes a first switch tube, a gate of the first switch tube is used to receive a first drive signal, a drain of the first switch tube is used to be electrically connected to the power supply, and a source of the first switch tube is electrically connected to the second switch module, the freewheeling module and the energy storage module, respectively.

[0007] In a possible implementation manner of the first aspect, the second switch module includes a second switch tube, a gate of the second switch tube is used to receive a second drive signal, a drain of the second switch tube is electrically connected to the first switch module, the freewheeling module and the energy storage module respectively, and a source of the second switch tube is grounded.

[0008] In a possible implementation manner of the first aspect, a difference between an impedance of the second switch tube and an impedance of the first switch tube is greater than a preset impedance.

[0009] In a possible implementation manner of the first aspect, the freewheeling module includes a first diode, an anode of the first diode is grounded, and a cathode of the first diode is electrically connected to the first switch module, the second switch module, and the energy storage module, respectively.

[0010] In a possible implementation manner of the first aspect, the first diode is a Schottky diode, an anode of the Schottky diode is grounded, and a cathode of the Schottky diode is electrically connected to the first switch module, the second switch module, and the energy storage module, respectively.

[0011] In a possible implementation of the first aspect, the energy storage module includes a first inductor and a first capacitor, the first end of the first inductor is electrically connected to the first switch module, the second switch module and the freewheeling module, respectively, the second end of the first inductor is electrically connected to the first end of the first capacitor and the load, and the second end of the first capacitor is grounded.

[0012] In a possible implementation of the first aspect, the power supply circuit also includes a driving module, which is electrically connected to the first switch module and the second switch module respectively; the driving module is used to output a first driving signal to the first switch module, and is also used to output a second driving signal to the second switch module.

[0013] In a possible implementation of the first aspect, the driving module includes a first driving unit and a second driving unit, the first driving unit is electrically connected to the first switch module, and the second driving unit is electrically connected to the second switch module; the first driving unit is used to output the first driving signal to the first switch module, and the second driving unit is used to output the second driving signal to the second switch module.

[0014] In a second aspect, an embodiment of the present application provides a voltage converter, comprising the power supply circuit described in any one of the first aspects.

[0015] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0016] The power supply circuit provided in the embodiment of the present application includes a first switch module, a second switch module, a freewheeling module and an energy storage module. When the load current is greater than a preset value, that is, the resistance of the load is small and the load demand current is large. If the first switch module and the second switch module are both in the disconnected state, the energy storage module can release energy through the freewheeling module to supply power to the load. If the first switch module is in the disconnected state and the second switch module is in the on state, the energy storage module can release energy through the freewheeling module and the second switch module to supply power to the load. Since the impedance of the freewheeling module is smaller than the impedance of the second switch module, when the load current is large, the energy storage module can be freewheeled through the freewheeling module with smaller impedance, thereby providing a larger output current for the load and continuously supplying power to the load. Therefore, the power supply circuit provided in the embodiment of the present application can provide a larger current to the load by adding a freewheeling module with smaller impedance, thereby expanding the application scope of the power supply circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 It is a circuit connection diagram of an existing power supply circuit;

[0019] Figure 2 is a principle block diagram of a power supply circuit provided in an embodiment of the present application;

[0020] Figure 3 is a circuit connection diagram of a power supply circuit provided in an embodiment of the present application;

[0021] Figure 4 is a schematic diagram of a working waveform of a load current increase provided by an embodiment of the present application;

[0022] Figure 5 This is a schematic diagram of the working principle of load current reduction provided by an embodiment of the present application;

[0023] Figure 6 This is a schematic diagram of a working waveform when the load current is reduced to no-load provided by an embodiment of the present application;

[0024] Figure 7 It is a circuit connection diagram of an existing asynchronous buck converter;

[0025] Figure 8 is a circuit connection diagram of another existing asynchronous buck converter;

[0026] Fig. 9 It is a schematic diagram of the working waveform in the existing fixed PWM no-load mode;

[0027] Fig.10 This is a schematic diagram of the working waveform in the existing PWM no-load mode;

[0028] Fig.11 is a principle block diagram of a power supply circuit provided in another embodiment of the present application;

[0029] Fig.12 is a principle block diagram of a power supply circuit provided in another embodiment of the present application;

[0030] Fig.13 It is a circuit connection diagram of a high duty cycle boost converter;

[0031] Fig.14 It is a circuit connection diagram of a high duty cycle buck-boost converter;

[0032] Fig.15 It is a circuit connection diagram of a high duty cycle inverting buck-boost converter.

[0033] In the figure, 10, power supply circuit; 101, first switch module; 102, second switch module; 103, freewheeling module; 104, energy storage module; 105, drive module; 1051, first drive unit; 1052, second drive unit; 20, load; 30, power supply. DETAILED DESCRIPTION

[0034] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0035] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0036] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0037] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0038] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0039] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0040] like Figure 1 As shown in the figure, the traditional DC-DC converter design usually adopts synchronous rectification technology, in which the upper switch tube (first switch tube HS) and the lower switch tube (second switch tube LS) are integrated. This design is very effective when the load current is small, because it can reduce energy loss and improve overall efficiency. However, when the load current becomes larger, such as 2A / 3A / 4A or even higher, if a fully integrated solution is still used, the chip area will increase sharply, which is unacceptable in terms of cost. Therefore, synchronous rectification technology can support small output current but cannot support large load; asynchronous rectification technology can support large load, but cannot reduce the use of diodes at low current, and each has its limitations.

[0041] Among them, the designer can select the type of the upper switch tube and the lower switch tube according to the actual situation, that is, both can use fully controlled power devices such as metal oxide field effect transistors or insulated gate bipolar transistors. For example, the upper switch tube and the lower switch tube can be selected as NMOS tubes.

[0042] Based on the above problems, the power supply circuit provided in the embodiment of the present application includes a first switch module, a second switch module, a freewheeling module and an energy storage module. When the load current is greater than the preset value, that is, the resistance of the load is small and the load demand current is large. If the first switch module and the second switch module are both in the disconnected state, the energy storage module can release energy through the freewheeling module to supply power to the load. If the first switch module is in the disconnected state and the second switch module is in the on state, the energy storage module can release energy through the freewheeling module and the second switch module to supply power to the load. Since the impedance of the freewheeling module is smaller than the impedance of the second switch module, when the load current is large, the energy storage module can be freewheeled through the freewheeling module with smaller impedance, thereby providing a larger output current for the load and continuously supplying power to the load. Therefore, the power supply circuit provided in the embodiment of the present application can provide a larger current to the load by adding a freewheeling module with smaller impedance, thereby expanding the application range of the power supply circuit.

[0043] In order to illustrate the technical solution described in this application, a specific embodiment is provided below for illustration.

[0044] Figure 2 FIG. 1 shows a principle block diagram of a power supply circuit 10 provided in an embodiment of the present application. Figure 2 As shown, the power supply circuit 10 includes a first switch module 101, a second switch module 102, a freewheeling module 103 and an energy storage module 104. The first switch module 101 is electrically connected to the second switch module 102, the freewheeling module 103 and the energy storage module 104, respectively. The freewheeling module 103 is electrically connected to the second switch module 102 and the energy storage module 104, respectively. The first switch module 101 is used to be electrically connected to the power supply 30, and the energy storage module 104 is used to be electrically connected to the load 20.

[0045] Specifically, when the current of the load 20 is greater than the preset value, that is, the resistance of the load 20 is small and the current demand of the load 20 is large. If the first switch module 101 and the second switch module 102 are both in the disconnected state, the energy storage module 104 can release energy through the freewheeling module 103, thereby supplying power to the load 20. If the first switch module 101 is in the disconnected state and the second switch module 102 is in the on state, the energy storage module 104 can release energy through the freewheeling module 103 and the second switch module 102, thereby supplying power to the load 20. Since the impedance of the freewheeling module 103 is smaller than the impedance of the second switch module 102, when the current of the load 20 is large, the energy storage module 104 can be freewheeled through the freewheeling module 103 with smaller impedance, thereby providing a larger output current for the load 20 and continuously supplying power to the load 20. Therefore, the power supply circuit 10 provided in the embodiment of the present application can provide a larger current to the load 20 by adding the freewheeling module 103 with smaller impedance, thereby expanding the application scope of the power supply circuit 10.

[0046] It should be noted that, since the freewheeling module 103 and the second switch module 102 are connected in parallel, and the freewheeling module 103 is always in operation, the voltage across the freewheeling module 103 remains substantially unchanged, that is, the voltage across the second switch module 102 remains substantially unchanged, and since the impedance of the second switch module 102 is fixed, the current flowing through the second switch module 102 remains substantially unchanged.

[0047] It should be noted that when the current of the load 20 is less than or equal to the preset value, the first switch module 101 is in the off state, and the second switch module 102 is in the on state, the freewheeling module 103 will not work. At this time, the energy storage module 104 only releases energy through the second switch module 102.

[0048] It should be noted that the preset value can be set according to the actual situation of the load 20 and the design requirements of the circuit, and is not limited here.

[0049] In one embodiment of the present application, Figure 3 As shown, the first switch module 101 includes a first switch tube HS, a gate of the first switch tube HS is used to receive a first drive signal HS-ON, a drain of the first switch tube HS is used to be electrically connected to the power supply 30, and a source of the first switch tube HS is electrically connected to the second switch module 102, the freewheeling module 103 and the energy storage module 104 respectively.

[0050] Specifically, the gate of the first switch tube HS is used to receive the first drive signal HS-ON, and is turned on or off according to the first drive signal HS-ON, so that the drain and source of the first switch tube HS are turned on or off. When the first drive signal HS-ON is a high-level signal, the first switch tube HS is turned on according to the high-level signal, so that the voltage VIN output by the power supply 30 can be transmitted to the energy storage module 104 and the load 20, thereby charging the energy storage module 104 and the load 20.

[0051] For example, the designer can select the type of the first switch tube HS according to the actual situation, that is, a fully controlled power device such as a metal oxide field effect transistor or an insulated gate bipolar transistor can be used. For example, the first switch tube HS can be selected as an NMOS tube.

[0052] In one embodiment of the present application, Figure 3 As shown, the second switch module 102 includes a second switch tube LS, the gate of the second switch tube LS is used to receive the second drive signal LS-ON, the drain of the second switch tube LS is electrically connected to the first switch module 101, the freewheeling module 103 and the energy storage module 104 respectively, and the source of the second switch tube LS is grounded.

[0053] Specifically, the gate of the second switch tube LS is used to receive the second drive signal LS-ON, and is turned on or off according to the second drive signal LS-ON, so that the drain and source of the second switch tube LS are turned on or off. When the second drive signal LS-ON is a high-level signal, the second switch tube LS is turned on according to the high-level signal, so that the energy storage module 104 can charge the load 20 through the second switch tube LS.

[0054] For example, the designer can select the type of the second switch tube LS according to the actual situation, that is, a fully controlled power device such as a metal oxide field effect transistor or an insulated gate bipolar transistor can be used. For example, the second switch tube LS can be selected as an NMOS tube.

[0055] It should be noted that the difference between the impedance of the second switch tube LS and the impedance of the first switch tube HS is greater than the preset impedance. Among them, the preset impedance can be selected according to the design requirements of the circuit. For example, the preset impedance can be a larger impedance. In the present application, the impedance of the first switch tube HS is designed to be much smaller than the impedance of the second switch tube LS, and can achieve 0~5A full load 20 range compatibility (including thermal performance, frequency jitter, large duty cycle operation and other characteristics). At the same time, the present application designs the first switch tube HS and the second switch tube LS as an asymmetric power tube structure, which can support both small current synchronous rectification output and large current asynchronous rectification output. At the same time, the size of the first switch tube HS and the second switch tube LS is small, which reduces the area and cost of the power supply circuit 10.

[0056] For example, the impedance of the first switch tube HS can be maintained at 200-300 milliohms according to the requirement of 3A / 4A, and the impedance of the second switch tube LS can be set to 700-800 milliohms according to the requirement of 1A.

[0057] In one embodiment of the present application, Figure 3 As shown, the freewheeling module 103 includes a first diode D1 , an anode of the first diode D1 is grounded, and a cathode of the first diode D1 is electrically connected to the first switch module 101 , the second switch module 102 and the energy storage module 104 , respectively.

[0058] Specifically, the first diode D1 has a unidirectional conduction function. When the current of the load 20 is greater than a preset value, the first switch tube HS and the second switch tube LS are both in the off state, and the energy storage module 104 releases energy through the first diode D1. When the current of the load 20 is greater than a preset value, the first switch tube HS is in the off state, and the second switch tube LS is in the on state, the energy storage module 104 releases energy through the first diode D1 and the second switch tube LS.

[0059] It should be noted that the first diode D1 can be a Schottky diode, the anode of the Schottky diode is grounded, and the cathode of the Schottky diode is electrically connected to the first switch module 101, the second switch module 102 and the energy storage module 104 respectively. Since the Schottky diode has a low forward voltage drop, usually between 0.2V and 0.4V, the power consumption when the Schottky diode is used for freewheeling is low, thereby improving the conversion efficiency of the voltage converter. At the same time, the switching speed of the Schottky diode is very fast, usually a few nanoseconds to tens of nanoseconds, which can greatly reduce the reverse recovery time, reduce electromagnetic interference, and improve the overall performance of the switching power supply.

[0060] In one embodiment of the present application, Figure 3 As shown, the energy storage module 104 includes a first inductor L1 and a first capacitor C1, the first end of the first inductor L1 is electrically connected to the first switch module 101, the second switch module 102 and the freewheeling module 103 respectively, the second end of the first inductor L1 is electrically connected to the first end of the first capacitor C1 and the load 20, and the second end of the first capacitor C1 is grounded.

[0061] Specifically, when the first switch tube HS is in the on state, the first inductor L1 and the first capacitor C1 are both used to store energy. When the first switch tube HS and the second switch tube LS are both in the off state, the first inductor L1 and the first capacitor C1 release energy through the first diode D1. When the first switch tube HS is in the off state and the second switch tube LS is in the on state, the first inductor L1 and the first capacitor C1 release energy through the first diode D1 and the second switch tube LS. By controlling the on and off of the first switch tube HS and the second switch tube LS, the energy storage module 104 stores energy and releases energy, thereby realizing that the power supply circuit 10 continuously supplies power to the load 20.

[0062] Combine the following Figure 3 The circuit diagram and Figure 4 , Figure 5 and Figure 6 The waveform diagram of the power supply circuit 10 is described in detail.

[0063] Wherein, SW is the voltage of the common terminal of the first switch tube HS and the second switch tube LS, IL is the current flowing through the first inductor L1, HS-ON is the first driving signal for driving the first switch tube HS, LS-ON is the second driving signal for driving the second switch tube LS, I D1 is the current flowing through the first diode D1, I LS is the current flowing through the second switch tube LS. Figure 4 2 is a waveform diagram of the load 20 current increase, wherein the solid line is the original waveform diagram, and the dotted line is the waveform diagram after the load 20 current increases. As the load 20 current increases, the current IL flowing through the first inductor L1 increases accordingly, and the current I flowing through the first diode D1 increases accordingly. D1 During this process, the first diode D1 is always in the freewheeling state, and the voltage across the first diode D1 remains basically unchanged. Since the first diode D1 is connected in parallel with the second switch tube LS, the voltage across the second switch tube LS remains basically unchanged. And the impedance of the second switch tube LS is fixed, so that the current I flowing through the second switch tube LS LS Basically remain unchanged.

[0064] Specifically, Figure 4 In the example, before time t0, the first switch tube HS is in the on state, the second switch tube LS is in the off state, the first inductor L1 stores energy, and the first inductor L1 does not release energy. Therefore, the current IL of the first inductor L1 increases, and the current I D1 is 0.

[0065] During the period t0 to t1, the first switch tube HS and the second switch tube LS are both in the off state, and the energy stored in the first inductor L1 is released through the first diode D1. Therefore, the current IL flowing through the first inductor L1 decreases, and the current I D1 Since the energy stored in the first inductor L1 is released through the first diode D1, the current I flowing through the first diode D1 D1 The falling slope is substantially the same as the falling slope of the current IL flowing through the first inductor L1. At time t1, the second switch tube LS is in the on state, and the energy stored in the first inductor L1 is released through the first diode D1 and the second switch tube LS. Since the impedance of the first diode D1 is smaller than that of the second switch tube LS, the current I flowing through the first diode D1 is D1 Much larger than the current I flowing through the second switch tube LS LS .

[0066] During the period t1 to t2, the first switch tube HS is in the off state, and the second switch tube LS is in the on state. The energy stored in the first inductor L1 is released through the first diode D1 and the second switch tube LS. The current I flowing through the first diode D1 is D1 The falling slope is still basically the same as the falling slope of the current IL flowing through the first inductor L1. During this process, the SW voltage remains basically unchanged. At time t2, the second switch tube LS is in the off state. At this time, the current I flowing through the second switch tube LS is LS is 0.

[0067] During the period t2 to t3, the first switch tube HS and the second switch tube LS are both in the off state, and the energy stored in the first inductor L1 is released through the first diode D1. Since the second switch tube LS is in the off state and no longer shunts, the current I flowing through the first diode D1 D1 At time t3, the first switch tube HS is turned on again, the first inductor L1 stores energy, the current IL flowing through the first inductor L1 increases, and the current I flowing through the first diode D1 increases. D1 is 0.

[0068] Figure 5 is a waveform diagram when the current of the load 20 decreases, wherein the solid line is the original waveform diagram, and the dotted line is the waveform diagram after the current of the load 20 increases.

[0069] Specifically, Figure 5 In the example, before time t0, the first switch tube HS is in the on state, the second switch tube LS is in the off state, the first inductor L1 stores energy, and the first inductor L1 does not release energy. Therefore, the current IL of the first inductor L1 increases, and the current I D1 is 0.

[0070] During the period t0 to t1, the first switch tube HS and the second switch tube LS are both in the off state, and the energy stored in the first inductor L1 is released through the first diode D1. Therefore, the current IL flowing through the first inductor L1 decreases, and the current I D1 As a result, the SW voltage decreases to -Vdiode. Since the energy stored in the first inductor L1 is released through the first diode D1, the current I flowing through the first diode D1 is D1 The falling slope is substantially the same as the falling slope of the current IL flowing through the first inductor L1. At time t1, the second switch tube LS is in the on state, the energy stored in the first inductor L1 is released through the first diode D1 and the second switch tube LS, and the current I flowing through the first diode D1 is D1 and the current I diverted to the second switch tube LS LS Basically equivalent.

[0071] During the period t1 to t2, the first switch tube HS is in the off state, and the second switch tube LS is in the on state. The energy stored in the first inductor L1 is released through the first diode D1 and the second switch tube LS. The current I flowing through the first diode D1 is D1 The falling slope is still substantially the same as the falling slope of the current IL flowing through the first inductor L1. At time t2, the current I flowing through the first diode D1 is D1 is 0, the first diode D1 is in a reverse cut-off state and no longer continues current.

[0072] In the stage t2~t3, the first switch tube HS is in the off state, and the second switch tube LS is in the on state. Since the first diode D1 is in the reverse cut-off state, the energy stored in the first inductor L1 is released through the second switch tube LS. Therefore, the SW voltage is -R dson-LS *IL, R dson-LS is the impedance of the second switch tube LS. As the current flowing through the first inductor L1 decreases, the SW voltage gradually increases. Since the energy stored in the first inductor L1 is released through the second switch tube LS. Therefore, the current I flowing through the second switch tube LS LS The falling slope is substantially the same as the falling slope of the current IL flowing through the first inductor L1. At t3, the first switch tube HS and the second switch tube LS are both in the off state, the first diode D1 continues to flow, the energy stored in the first inductor L1 is released through the first diode D1, and the SW voltage is reduced to the conduction voltage of the first diode D1. Since the current flowing through the first diode D1 at t3 is lower than the current in the t0~t1 stage, the conduction voltage is slightly lower than Vdiode.

[0073] During the period from t3 to t4, the first switch tube HS and the second switch tube LS are both in the off state, the first diode D1 is still freewheeling, and the energy stored in the first inductor L1 is released through the first diode D1. At t4, the first switch tube HS is in the on state again, the first inductor L1 stores energy, the current IL flowing through the first inductor L1 increases, and the current I flowing through the first diode D1 increases. D1 is 0.

[0074] Figure 6 It is a waveform diagram of the load 20 current decreasing to no-load.

[0075] Specifically, Figure 6 In the example, before time t0, the first switch tube HS is in the on state, the second switch tube LS is in the off state, the first inductor L1 stores energy, and the first inductor L1 does not release energy. Therefore, the current IL of the first inductor L1 increases, and the current I D1 is 0.

[0076] During the period t0 to t1, the first switch tube HS and the second switch tube LS are both in the off state, and the energy stored in the first inductor L1 is released through the first diode D1. Therefore, the current IL flowing through the first inductor L1 decreases, and the current I D1 At time t1, the second switch tube LS is in the on state, the energy stored in the first inductor L1 is released through the first diode D1 and the second switch tube LS, and the current I flowing through the first diode D1 is D1 is smaller than the current I diverted to the second switch tube LS LS .

[0077] During the period t1 to t2, the first switch tube HS is in the off state, and the second switch tube LS is in the on state. The energy stored in the first inductor L1 is released through the first diode D1 and the second switch tube LS. The current I flowing through the first diode D1 is D1 The falling slope is still substantially the same as the falling slope of the current IL flowing through the first inductor L1. At time t2, the current I flowing through the first diode D1 is D1 is 0, the first diode D1 is in a reverse cut-off state and no longer continues current.

[0078] In the stage t2~t3, the first switch tube HS is in the off state, and the second switch tube LS is in the on state. Since the first diode D1 is in the reverse cut-off state, the energy stored in the first inductor L1 is released through the second switch tube LS. Therefore, the SW voltage is -R dson-LS *IL, R dson-LSis the impedance of the second switch tube LS. As the current flowing through the first inductor L1 decreases, the SW voltage gradually increases. Since the energy stored in the first inductor L1 is released through the second switch tube LS. Therefore, the current I flowing through the second switch tube LS LS The falling slope is substantially the same as the falling slope of the current IL flowing through the first inductor L1. At time t3, the zero-crossing detection comparator of the second switch tube LS is triggered to flip, thereby turning off the second switch tube LS. At this time, both the first switch tube HS and the second switch tube LS are in the off state. However, the current on the first inductor L1 has not completely reached 0A, and at this time, the first diode D1 continues to flow again.

[0079] During the period t3 to t4, the first switch tube HS and the second switch tube LS are both in the off state, the first diode D1 is still freewheeling, and the energy stored in the first inductor L1 is released through the first diode D1. In this process, the current I flowing through the first diode D1 D1 is smaller, therefore, the voltage of SW is higher than -Vdiode. At time t4, the current IL flowing through the first inductor L1 decreases to 0A, that is, the energy stored in the first inductor L1 has been completely released.

[0080] During the period t4-t5, the first switch tube HS and the second switch tube LS are both in the off state, the first inductor L1 does not store or release energy, and the SW voltage and the output voltage V OUT At time t5, the first switch tube HS is turned on again, the first inductor L1 stores energy, the current IL flowing through the first inductor L1 increases, and the current I flowing through the first diode D1 decreases. D1 is 0.

[0081] It should be noted that for Figure 1 The existing problem is that the prior art discloses a solution of an asynchronous buck converter, such as Figure 7 As shown. The asynchronous buck converter can support large output current and solve Figure 1 However, the asynchronous buck converter cannot support special scenarios such as large duty cycle, and special design circuits need to be added, such as Figure 8 The circuit in the dashed box is shown. In large duty cycle applications, that is, VIN and V OUT When the voltage is close to the input voltage, the circuit in the dotted box needs to work periodically to charge the bootstrap capacitor so that the upper switch tube can work normally. This also increases the chip cost and design complexity. In addition, the asynchronous buck converter cannot support the reverse function and has no fixed PWM mode, such as Fig. 9As shown. Since the diode can only conduct in the forward direction and cut off in the reverse direction, the inductor current cannot flow from the output to GND when the load is light (the load current is less than or equal to the preset value). It can only work at a reduced frequency when the load is light, that is, PFM (Pulse-Frequency-Modulation). Fig.10 As shown in the figure, the output ripple is large, which causes great interference to the subsequent system and indirectly leads to the inability to achieve frequency spreading characteristics under light load.

[0082] In view of the problems existing in asynchronous buck converters, the power supply circuit 10 provided in the present application can support light load fixed PWM mode operation in any scenario, reduce output ripple, and improve transient response. It can also support large duty cycle operation, support frequency spread spectrum characteristics, and reduce electromagnetic interference.

[0083] In one embodiment of the present application, Fig.11 As shown, the power supply circuit 10 further includes a driving module 105 , and the driving module 105 is electrically connected to the first switch module 101 and the second switch module 102 .

[0084] Specifically, the driving module 105 outputs a first driving signal HS-ON to the first switch module 101 to turn on or off the first switch module 101. The driving module 105 also outputs a second driving signal LS-ON to the second switch module 102 to turn on or off the second switch module 102. The first driving signal HS-ON and the second driving signal LS-ON are both PWM signals.

[0085] In one embodiment of the present application, Fig.12 As shown, the driving module 105 includes a first driving unit 1051 and a second driving unit 1052 . The first driving unit 1051 is electrically connected to the first switch module 101 , and the second driving unit 1052 is electrically connected to the second switch module 102 .

[0086] Specifically, the first driving unit 1051 is used to output a first driving signal HS-ON to the first switch module 101 to turn on or off the first switch module 101. The second driving unit 1052 is used to output a second driving signal LS-ON to the second switch module 102 to turn on or off the second switch module 102.

[0087] It should be noted that the first driving unit 1051 and the second driving unit 1052 may include an amplifier, a driver or a transistor, etc., for amplifying the input signal and providing it with sufficient current and voltage amplitude to drive the first switch module 101 and the second switch module 102. The first driving unit 1051 and the second driving unit 1052 may both be timing control circuits for generating correct timing signals for controlling the switch tube to be turned on and off.

[0088] The present application also discloses a voltage converter, including the above-mentioned power supply circuit 10. The voltage converter adopts the above-mentioned power supply circuit 10 to provide a larger current for the load and improve the conversion efficiency of the voltage converter.

[0089] It should be noted that the above embodiments are all based on buck converters as an example to illustrate the present application scheme, but are not limited to this. The present application scheme is also applicable to boost converters with high duty cycles. Fig.13 As shown, the present application is also applicable to a buck-boost converter with a high duty cycle. Fig.14 As shown, the present application is also applicable to a high duty cycle reverse buck-boost converter. Fig.15 Since the working principles of the high duty cycle boost converter, the high duty cycle buck-boost converter and the high duty cycle reverse buck-boost converter are similar to the working principles of the above-mentioned buck converter, they will not be described in detail here.

[0090] Since the processing and functions implemented by the voltage converter in this embodiment basically correspond to the embodiments, principles and examples of the aforementioned power supply circuit, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0091] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A power supply circuit, characterized in that: It includes a first switch module, a second switch module, a freewheeling module and an energy storage module, wherein the first switch module is electrically connected to the second switch module, the freewheeling module and the energy storage module respectively, the freewheeling module is electrically connected to the second switch module and the energy storage module respectively, the first switch module is used to be electrically connected to a power supply, and the energy storage module is used to be electrically connected to a load; When the load current is greater than a preset value, and the first switch module and the second switch module are both in an off state, the energy storage module is used to release energy through the freewheeling module; when the load current is greater than a preset value, and the first switch module is in an off state, and the second switch module is in an on state, the energy storage module is also used to release energy through the freewheeling module and the second switch module, wherein the impedance of the freewheeling module is less than the impedance of the second switch module; The first switch module includes a first switch tube, the gate of the first switch tube is used to receive the first drive signal, the drain of the first switch tube is used to be electrically connected to the power supply, and the source of the first switch tube is electrically connected to the first end of the second switch module, the first end of the freewheeling module and the first end of the energy storage module respectively; The second switch module includes a second switch tube, the gate of the second switch tube is used to receive the second drive signal, the drain of the second switch tube is the first end of the second switch module and is electrically connected to the source of the first switch tube, the source of the second switch tube is the second end of the second switch module and is connected to the ground, the second end of the freewheeling module and the third end of the energy storage module are both grounded, and the second end of the energy storage module is used to be electrically connected to the load; The difference between the impedance of the second switch tube and the impedance of the first switch tube is greater than a preset impedance; The impedance of the first switch tube is much smaller than the impedance of the second switch tube.

2. The power supply circuit according to claim 1, characterized in that: The freewheeling module includes a first diode, an anode of the first diode is the second end of the freewheeling module and is connected to the ground, and a cathode of the first diode is the first end of the freewheeling module and is electrically connected to the first switch module, the second switch module and the energy storage module respectively.

3. The power supply circuit according to claim 2, characterized in that: The first diode is a Schottky diode, the anode of the Schottky diode is grounded, and the cathode of the Schottky diode is electrically connected to the first switch module, the second switch module and the energy storage module respectively.

4. The power supply circuit according to claim 1, characterized in that: The energy storage module includes a first inductor and a first capacitor, wherein the first end of the first inductor is the first end of the energy storage module and is electrically connected to the first switch module, the second switch module and the freewheeling module respectively, the second end of the first inductor is the second end of the energy storage module and is electrically connected to the first end of the first capacitor and the load respectively, and the second end of the first capacitor is the third end of the energy storage module and is connected to the ground.

5. The power supply circuit according to any one of claims 1 to 4, characterized in that: The power supply circuit also includes a driving module, which is electrically connected to the first switch module and the second switch module respectively; the driving module is used to output a first driving signal to the first switch module, and is also used to output a second driving signal to the second switch module.

6. The power supply circuit according to claim 5, characterized in that: The driving module includes a first driving unit and a second driving unit, the first driving unit is electrically connected to the first switch module, and the second driving unit is electrically connected to the second switch module; the first driving unit is used to output the first driving signal to the first switch module, and the second driving unit is used to output the second driving signal to the second switch module.

7. A voltage converter, characterized in that: The invention comprises the power supply circuit according to any one of claims 1 to 6.

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