Power supply circuit and switching power supply

Abstract

The embodiment of the invention provides a power supply circuit and a switching power supply. The power supply circuit (100) supplies power to a power utilization circuit, and comprises a starting circuit (1) and a countercurrent prevention circuit (2), the starting circuit (1) supplies power to a power supply terminal of the power utilization circuit through the countercurrent prevention circuit (2) in the starting process of the power utilization circuit, and after the power utilization circuit is started, the starting circuit (1) stops supplying power to the power supply terminal of the power utilization circuit, and the countercurrent prevention circuit (2) stops supplying power to the power supply terminal of the power utilization circuit. A reverse flow prevention circuit (2) prevents reverse flow from a power supply terminal to a start-up circuit (1), the reverse flow prevention circuit (2) including an N-type MOSFET device (21), the source and gate of the N-type MOSFET device (21) being connected to the start-up circuit (1), the drain of the N-type MOSFET device (21) being connected to the power supply terminal of an electrical circuit (200), and the source and back gate of the N-type MOSFET device (21) being connected by a first resistor (22).

Description

Technical Field

[0001] The embodiments of the present application relate to the field of circuits, and in particular to a power supply circuit and a switching power supply. Background Art

[0002] In electronic devices, multiple power supply paths or multiple power supplies are widely used to supply power to the power circuits in the electronic devices. Taking multiple power supply paths as an example, the power terminal of the power circuit can be connected to the first power supply path and the second power supply path. In the case where the voltages output by the first power supply path and the second power supply path to the power terminal of the power circuit are different, the first power supply path with a high output voltage will generate backflow to the second power supply path with a low output voltage, forming a reverse current (hereinafter referred to as reverse current) on the second power supply path. When the voltage difference between the first power supply path and the second power supply path exceeds a certain range, it is easy to cause damage to the circuit. At present, reverse current can be prevented by diodes, relays, MOSFET devices (metal-oxide semiconductor field effect transistors), etc.

[0003] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and facilitating the understanding of those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0004] The inventors have found that when a MOSFET device with a body diode is used to prevent reverse current, when the MOSFET device is turned on, the current of the MOSFET device is shunted due to the influence of the parasitic transistor of the MOSFET device, resulting in a reduction in the current provided to the power supply terminal of the power circuit. In addition, in the existing circuit that uses MOSFET devices to prevent reverse current, the circuit structure is relatively complex, the circuit occupies a large space, and is not conducive to the miniaturization of the integrated circuit (IC).

[0005] In response to at least one of the above problems, an embodiment of the present application provides a power supply circuit and a switching power supply.

[0006] According to one aspect of an embodiment of the present application, a power supply circuit is provided, which provides power to a power-consuming circuit, the power supply circuit comprising a startup circuit and a backflow prevention circuit, during the startup of the power-consuming circuit, the startup circuit provides power to the power terminal of the power-consuming circuit via the backflow prevention circuit, after the power-consuming circuit is started, the startup circuit stops providing power to the power terminal of the power-consuming circuit, and the backflow prevention circuit prevents backflow from the power terminal to the startup circuit, wherein the backflow prevention circuit comprises an N-type MOSFET device, a source and a gate of the N-type MOSFET device are connected to the startup circuit, a drain is connected to the power terminal of the power-consuming circuit, and a source and a back gate of the N-type MOSFET device are connected via a first resistor.

[0007] According to another aspect of an embodiment of the present application, a switching power supply is provided, the switching power supply comprising: a power-consuming circuit; and a power supply circuit as described in one aspect of an embodiment of the present application, which supplies power to the power-consuming circuit.

[0008] One of the beneficial effects of the embodiment of the present application is that by inserting a first resistor between the source and the back gate of the N-type MOSFET device of the backflow prevention circuit, the base current of the parasitic PNP transistor of the N-type MOSFET device can be suppressed, thereby suppressing the parasitic current, and then reliably providing current to the power supply terminal of the power circuit. In addition, by connecting the source and gate of the N-type MOSFET device to the startup circuit, the N-type MOSFET device can be controlled to be turned on or off by the startup circuit, thereby simplifying the structure of the backflow prevention circuit, which is helpful for miniaturization of the backflow prevention circuit and reducing losses.

[0009] With reference to the following description and accompanying drawings, the specific embodiments of the present application are disclosed in detail, indicating the way in which the principles of the present application can be adopted. It should be understood that the embodiments of the present application are not limited in scope. Within the scope of the spirit and clauses of the appended claims, the embodiments of the present application include many changes, modifications and equivalents.

[0010] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0011] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The elements and features described in one figure or one implementation of the present application embodiment may be combined with the elements and features shown in one or more other figures or implementations. In addition, in the accompanying drawings, similar reference numerals represent corresponding parts in several figures and can be used to indicate corresponding parts used in more than one implementation.

[0013] Figure 1 is a schematic diagram of a power supply circuit according to an embodiment of the present application;

[0014] Figure 2 is a schematic diagram of a backflow prevention circuit according to an embodiment of the present application;

[0015] Figure 3 is a schematic diagram of a switching power supply according to an embodiment of the present application;

[0016] Figure 4 is another schematic diagram of a switching power supply according to an embodiment of the present application;

[0017] Figure 5 is another schematic diagram of a backflow prevention circuit according to an embodiment of the present application;

[0018] Figure 6 is another schematic diagram of a power supply circuit according to an embodiment of the present application;

[0019] Figure 7 is another schematic diagram of a switching power supply according to an embodiment of the present application;

[0020] Figure 8 It is a schematic diagram of an electric circuit according to an embodiment of the present application. DETAILED DESCRIPTION

[0021] With reference to the accompanying drawings, the above and other features of the present application will become apparent through the following description. In the description and the accompanying drawings, specific embodiments of the present application are specifically disclosed, which show some embodiments in which the principles of the present application can be adopted. It should be understood that the present application is not limited to the described embodiments. On the contrary, the present application includes all modifications, variations and equivalents falling within the scope of the attached claims.

[0022] In the embodiments of the present application, the terms "first", "second", etc. are used to distinguish different elements in terms of title, but do not indicate the spatial arrangement or temporal order of these elements, etc., and these elements should not be limited by these terms. The term "and / or" includes any one and all combinations of one or more of the associated listed terms. The terms "comprising", "including", "having", etc. refer to the presence of the stated features, elements, components or components, but do not exclude the presence or addition of one or more other features, elements, components or components.

[0023] In the embodiments of the present application, the singular forms "a", "the", etc. include plural forms and should be broadly understood as "a kind" or "a type" rather than being limited to the meaning of "one"; in addition, the term "said" should be understood to include both singular and plural forms, unless the context clearly indicates otherwise. In addition, the term "according to" should be understood as "at least in part according to...", and the term "based on" should be understood as "at least in part based on...", unless the context clearly indicates otherwise.

[0024] Embodiments of the first aspect

[0025] An embodiment of the present application provides a power supply circuit.

[0026] Figure 1 Schematic diagram of a power supply circuit according to an embodiment of the present application. Figure 1 As shown, the power supply circuit 100 includes: a starting circuit 1 and a backflow prevention circuit 2. The power supply circuit 100 provides power to the power-consuming circuit. During the startup of the power-consuming circuit, the starting circuit 1 provides power to the power terminal of the power-consuming circuit via the backflow prevention circuit 2. After the power-consuming circuit is started, the starting circuit 1 stops providing power to the power terminal of the power-consuming circuit, and the backflow prevention circuit 2 prevents the backflow from the power terminal to the starting circuit 1. Among them, the backflow prevention circuit 2 includes an N-type MOSFET device 21, the source S and the gate G of the N-type MOSFET device 21 are connected to the starting circuit 1, the drain D is connected to the power terminal of the power-consuming circuit, and the source S and the back gate B of the N-type MOSFET device 21 are connected through a first resistor 22.

[0027] In addition, the N-type MOSFET device 21 has a body diode between the source and the drain due to the device structure (the back gate side is the anode and the drain side is the cathode).

[0028] It is worth noting that the above Figure 1 The power supply circuit of the embodiment of the present application is only schematically described, but the present application is not limited thereto. For example, the connection relationship between the modules or components can be appropriately adjusted, and other modules or components can be added, or some modules or components can be reduced. Those skilled in the art can make appropriate modifications based on the above content, and are not limited to the above attached. Figure 1 Records of.

[0029] According to the above embodiment, by inserting the first resistor 22 between the source S and the back gate B of the N-type MOSFET device 21 of the backflow prevention circuit 2, the base current of the parasitic PNP transistor of the N-type MOSFET device 21 can be suppressed, thereby suppressing the parasitic current, and then reliably providing current to the power supply terminal of the power circuit. In addition, by connecting the source S and the gate G of the N-type MOSFET device 21 to the startup circuit 1, the N-type MOSFET device 21 can be controlled to be turned on or off by the startup circuit 1, thereby simplifying the structure of the backflow prevention circuit 2, which helps to miniaturize the backflow prevention circuit 2 and reduce losses.

[0030] Figure 2 2 is a schematic diagram of a backflow prevention circuit 2 according to an embodiment of the present application. Figure 2 As shown, in the backflow prevention circuit 2, the N-type MOSFET device 21 has a parasitic PNP transistor 211. Due to the influence of the parasitic PNP transistor 211, when the N-type MOSFET device 21 becomes a conducting state including a body diode, a part of the current flows from the source S of the N-type MOSFET device 21 to the drain D, and is then provided to the power supply terminal of the power circuit; the other part of the current (parasitic current) flows to the substrate (Substrate) of the N-type MOSFET device 21. When the parasitic current reaches a certain value, it is easy to cause the current provided to the power circuit to not meet the preset requirements. By inserting a first resistor 22 between the source S and the back gate B of the N-type MOSFET device 21, the base current of the parasitic PNP transistor 211 can be suppressed, thereby achieving the purpose of suppressing the parasitic current.

[0031] In some embodiments, the power supply circuit 100 can be applied in various circuits, devices or equipment, or connected to various circuits, devices or equipment. For example, the power supply circuit 100 can be applied in a switching power supply. Figure 3 Schematic diagram of a switching power supply according to an embodiment of the present application. Figure 3 As shown, in the switching power supply 1000, the power supply circuit 100 supplies power to the power terminal (e.g., the VCC terminal) of the power-consuming circuit 200, wherein the power-consuming circuit 200 may be an internal circuit of the switching power supply 1000 powered by the VCC terminal, for example, a control circuit that controls the output pulse of the switching power supply 1000, etc.

[0032] It is worth noting that the above Figure 3 The switching power supply of the embodiment of the present application is only schematically described, but the present application is not limited thereto. For example, the connection relationship between the modules or components can be appropriately adjusted, and other modules or components can be added, or some modules or components can be reduced. Those skilled in the art can make appropriate modifications based on the above content, and are not limited to the above attached Figure 3Records of.

[0033] In some embodiments, the startup circuit 1 can provide power to the power terminal VCC of the power circuit 200 according to the state of the power circuit 200. In other words, during the startup of the power circuit 200, the startup circuit 1 provides power to the power terminal VCC of the power circuit 200 via the backflow prevention circuit 2. After the power circuit 200 is started, the startup circuit 1 stops providing power to the power terminal VCC of the power circuit 200, and the backflow prevention circuit 2 prevents the backflow from the power terminal VCC to the startup circuit 1. This helps to provide the power circuit 200 with power that meets the requirements during the startup of the power circuit 200, and prevents backflow to the startup circuit 1 after the power circuit 200 is started, thereby improving the safety of the circuit.

[0034] Figure 4 FIG. 1 is another schematic diagram of the switching power supply 1000 according to an embodiment of the present application. Figure 4 As shown, the switching power supply 1000 may further include a power supply circuit 3. The startup circuit 1 and the power supply circuit 3 are connected to an input power line not shown in the figure, the backflow prevention circuit 2 is connected to the second end of the power supply circuit 3, and the second end is connected to the power terminal VCC of the power circuit 200. The present application is not limited thereto, for example, the power supply circuit 100 may be integrated into the power consumption circuit (power consumption circuit), or the power consumption circuit may be independent of the power supply circuit 100.

[0035] In some embodiments, the power supply circuit 3 can be various types of circuits, for example, it can be a circuit that converts alternating current into direct current, a battery, and the like.

[0036] In some embodiments, after the powered circuit 200 is started, the power supply circuit 3 can directly supply power to the power terminal VCC of the powered circuit 200. Thus, after the powered circuit 200 based on the start-up circuit 1 is started, the power consumption of the start-up circuit 1 is stopped.

[0037] The startup voltage of the power circuit 200 may be different from the working voltage after startup, that is, the startup voltage is a voltage higher than the working voltage. After the power circuit 200 based on the startup circuit 1 is started, a suitable working voltage can be provided to the power circuit 200 through the second end of the power supply circuit 3.

[0038] In some embodiments, the startup circuit 1 can provide a control signal to the gate G of the N-type MOSFET device 21 according to the state of the power supply circuit 3, thereby supplying startup power to the power-consuming circuit 200. That is, the on / off control of the current is performed by making the N-type MOSFET device 21 in the ON / OFF state. For example, during the startup of the power-consuming circuit 200, the startup circuit 1 provides a control signal to the gate G of the N-type MOSFET device 21 to turn on the N-type MOSFET device 21; after the power-consuming circuit 200 is started, the startup circuit 1 provides a control signal to the gate G of the N-type MOSFET device 21 to turn off the N-type MOSFET device 21.

[0039] In some embodiments, the startup circuit 1 can provide a control signal to the source S of the N-type MOSFET device 21 according to the state of the power supply circuit 3, thereby supplying startup power to the power-consuming circuit 200. That is, the on / off control of the current is performed by the potential difference at both ends of the body diode. For example, during the startup of the power-consuming circuit 200, the startup circuit 1 provides a high level to the source S of the N-type MOSFET device 21, thereby turning on the body diode of the N-type MOSFET device 21; after the power-consuming circuit 200 is started, the startup circuit 1 provides a low level to the source S of the N-type MOSFET device 21, thereby turning off the body diode of the N-type MOSFET device 21, and avoiding reverse flow from the power terminal of the power-consuming circuit 200 to the startup circuit 1.

[0040] In some embodiments, during the startup of the power circuit 200 , the startup circuit 1 may provide a voltage higher than the back gate B to the gate G of the N-type MOSFET device 21 , thereby improving the conduction capability of the N-type MOSFET device 21 .

[0041] Figure 5 is another schematic diagram of the backflow prevention circuit of the embodiment of the present application. Figure 5 As shown, the gate G of the N-type MOSFET device 21 is connected to the source S, so that the gate voltage V G Equal to the source voltage V S The function of the reverse current prevention circuit is realized by the body diode of the N-type MOSFET device 21. In addition, the back gate of the N-type MOSFET device 21 is connected to the gate-source via the first resistor 22. The emitter of the parasitic PNP transistor 211 is connected to the gate-source via the first resistor 22, so the emitter current of the parasitic PNP transistor 211 is limited, and similarly, the collector current as a parasitic current is greatly limited.

[0042] In some embodiments, the gate voltage of the N-type MOSFET device 21 may be increased in various ways. Figure 6FIG. 1 is another schematic diagram of the power supply circuit 100 according to an embodiment of the present application. Figure 6 As shown, in the power supply circuit 100, the startup circuit 1 may include a first MOSFET device 11, and a gate G of the first MOSFET device 11 is connected to a gate G of an N-type MOSFET device 21. By connecting the gate G of the N-type MOSFET device 21 to the gate G of the first MOSFET device 11, the gate voltage of the N-type MOSFET device 21 can be increased without increasing the complexity of the circuit.

[0043] In some embodiments, Figure 6 As shown, the drain D of the first MOSFET device 11 is connected to the input terminal A of the starting circuit 1, and the source S is connected to the source S of the N-type MOSFET device 21. During the startup of the power circuit 200, the gate G of the first MOSFET device 11 is provided with a high level, and the first MOSFET device 11 is turned on, so that the current flowing through the body diode flows from the source via the drain, and the loss of the forward voltage of the body diode is reduced to the loss of the on-resistance; after the power circuit 200 is started, the gate G of the first MOSFET device 11 is provided with a low level, and the first MOSFET device 11 is turned off.

[0044] In some embodiments, the gate G of the first MOSFET device 11 may be connected to the drain D of the first MOSFET device 11 through a second resistor 12 .

[0045] In some embodiments, the first MOSFET device 11 may include HVLDMOS (High Voltage Laterally Diffused Metal Oxide Semiconductor). Thus, the output power of the startup circuit 1 can be increased, the gate-source breakdown voltage can be increased, etc. The present application is not limited thereto, and the first MOSFET device 11 may also include other components, such as JFET (Junction Field-Effect Transistor), or a combination of HVLDMOS and JFET, etc.

[0046] In some embodiments, Figure 6 As shown, the startup circuit 1 may further include a switch device 13. The switch device 13 may include a second MOSFET device 131. The drain D of the second MOSFET device 131 is connected to the gate G of the first MOSFET device 11, the source S of the second MOSFET device 131 is grounded, and the gate G of the second MOSFET device 131 is provided with a corresponding control signal according to the state of the power circuit 200.

[0047] Taking the second MOSFET device 131 as an N-type MOSFET as an example, during the startup of the power circuit 200, a low level is applied to the gate G of the second MOSFET device 131, so that the second MOSFET device 131 is turned off; after the power circuit 200 is started, a high level is applied to the gate G of the second MOSFET device 31 to turn on the second MOSFET device 31, so that a low level can be applied to the gate G of the first MOSFET device 11 and the gate of the N-type MOSFET device 21, so that the first MOSFET device 11 and the N-type MOSFET device 21 are turned off. The present application is not limited to this, and the second MOSFET device 131 can be other types of devices.

[0048] In some embodiments, Figure 6 As shown, the startup circuit 1 can also be used to clamp the voltage of the switch device 13. One end of the second MOSFET device 131 of the switch device 13 and the negative electrode of the voltage stabilizing diode 132 are connected to the gate of the first MOSFET device 11, and the other end and the positive electrode of the voltage stabilizing diode 132 are grounded. During the startup of the power circuit 200, the switch device 13 is turned off, and the drain voltage of the second MOSFET device 131 is the sum of the VCC voltage, the constant current circuit 14 and the gate-source voltage of the first MOSFET device 11. The sum may exceed the withstand voltage of the second MOSFET device 131, so it can be clamped by the voltage stabilizing voltage of the voltage stabilizing diode 132 to avoid applying overvoltage.

[0049] Figure 7 FIG. 1 is another schematic diagram of a switching power supply 1000 according to an embodiment of the present application. Figure 7 As shown, the switching power supply 1000 may include a semiconductor device 300. The semiconductor device 300 integrates a power supply circuit 100 and a power consumption circuit 200, and is used to control the power supply circuit 3. Figure 7 As shown, the first end K1 of the power supply circuit 3 is connected to the input end A of the start-up circuit 1 , and the second end K2 of the power supply circuit 3 is connected to the VCC terminal of the power-consuming circuit 200 .

[0050] like Figure 7 As shown, the power supply circuit 100 may be independent of the power consumption circuit 200 and is not integrated into the power consumption circuit 200 .

[0051] Figure 8 FIG. 2 is a schematic diagram of a power circuit 200 according to an embodiment of the present application. Figure 8 As shown, the power supply circuit 100 can be integrated into the power consumption circuit 200, and during the startup process of the power consumption circuit 200, a startup voltage is provided to the internal circuit connected to the VCC terminal. Figure 8 As shown, the switching device of the power supply circuit 3 can be built-in.

[0052] It is worth noting that the above Figures 7 and 8 The switching power supply of the embodiment of the present application is only schematically described, but the present application is not limited thereto. For example, the connection relationship between the modules or components can be appropriately adjusted, and other modules or components can be added, or some modules or components can be reduced. Those skilled in the art can make appropriate modifications based on the above content, and are not limited to the above attached Figure 7 To Attachment Figure 8 Records of.

[0053] The above embodiments are merely exemplary of the embodiments of the present application, but the present application is not limited thereto, and appropriate modifications may be made based on the above embodiments. For example, the above embodiments may be used alone, or one or more of the above embodiments may be combined.

[0054] It can be seen from the above embodiments that by inserting a first resistor between the source and the back gate of the N-type MOSFET device of the backflow prevention circuit, the base current of the parasitic PNP transistor of the N-type MOSFET device can be suppressed, thereby suppressing the parasitic current, and then reliably providing current to the power supply terminal of the power circuit. In addition, by connecting the gate of the N-type MOSFET device to the startup circuit, the N-type MOSFET device can be controlled to be turned on or off by the startup circuit, thereby simplifying the structure of the backflow prevention circuit, which helps to miniaturize the backflow prevention circuit and reduce losses.

[0055] Embodiments of the second aspect

[0056] The present application also provides a semiconductor device. The semiconductor device may include the power supply circuit described in the embodiment of the first aspect. For example, the semiconductor device may be the semiconductor device 300 in the embodiment of the first aspect. The same contents as those in the embodiment of the first aspect are not repeated here.

[0057] In some embodiments, the semiconductor device may further include a power-consuming circuit, and the power supply circuit provides power to the power-consuming circuit.

[0058] The above embodiments are merely exemplary of the embodiments of the present application, but the present application is not limited thereto, and appropriate modifications may be made based on the above embodiments. For example, the above embodiments may be used alone, or one or more of the above embodiments may be combined.

[0059] It can be seen from the above embodiments that in the power supply circuit, by inserting a first resistor between the source and the back gate of the N-type MOSFET device of the backflow prevention circuit, the base current of the parasitic PNP transistor of the N-type MOSFET device can be suppressed, thereby suppressing the parasitic current, and then reliably providing current to the power supply terminal of the power-consuming circuit. In addition, by connecting the gate of the N-type MOSFET device to the startup circuit, the N-type MOSFET device can be controlled to be turned on or off by the startup circuit, thereby simplifying the structure of the backflow prevention circuit, which is helpful for miniaturization of the backflow prevention circuit and reducing losses.

[0060] Embodiments of the third aspect

[0061] The present application also provides a switching power supply. The switching power supply may include the semiconductor device described in the first and second aspects and the power supply circuit described in the first aspect. The same contents as those in the first and second aspects are not repeated here.

[0062] The above embodiments are merely exemplary of the embodiments of the present application, but the present application is not limited thereto, and appropriate modifications may be made based on the above embodiments. For example, the above embodiments may be used alone, or one or more of the above embodiments may be combined.

[0063] It can be seen from the above embodiments that in the power supply circuit, by inserting a first resistor between the source and the back gate of the N-type MOSFET device of the backflow prevention circuit, the base current of the parasitic PNP transistor of the N-type MOSFET device can be suppressed, thereby suppressing the parasitic current, and then reliably providing current to the power supply terminal of the power-consuming circuit. In addition, by connecting the gate of the N-type MOSFET device to the startup circuit, the N-type MOSFET device can be controlled to be turned on or off by the startup circuit, thereby simplifying the structure of the backflow prevention circuit, which is helpful for miniaturization of the backflow prevention circuit and reducing losses.

Claims

1. A power supply circuit (100) for supplying power to a power consumption circuit (200), characterized in that: The power supply circuit (100) comprises a starting circuit (1) and a backflow prevention circuit (2). During the starting process of the power-consuming circuit (200), the starting circuit (1) supplies power to the power terminal of the power-consuming circuit (200) via the backflow prevention circuit (2). After the power-consuming circuit (200) is started, the starting circuit (1) stops supplying power to the power terminal of the power-consuming circuit (200). The backflow prevention circuit (2) prevents backflow from the power terminal to the starting circuit (1). The backflow prevention circuit (2) comprises an N-type MOSFET device (21), the source and gate of the N-type MOSFET device (21) are connected to the start-up circuit (1), the drain is connected to the power supply terminal of the power-consuming circuit (200), and the source and back gate of the N-type MOSFET device (21) are connected via a first resistor (22).

2. The power supply circuit according to claim 1, characterized in that: During the startup process of the power-consuming circuit (200), the startup circuit (1) provides a control signal to the gate of the N-type MOSFET device (21) to turn on the N-type MOSFET device (21); After the power consumption circuit (200) is started, the start-up circuit (1) provides a control signal to the gate of the N-type MOSFET device (21) to turn off the N-type MOSFET device (21).

3. The power supply circuit according to claim 1, characterized in that: The startup circuit (1) comprises a first MOSFET device (11), wherein the gate of the first MOSFET device (11) is connected to the gate of the N-type MOSFET device (21).

4. The power supply circuit according to claim 3, characterized in that: The drain of the first MOSFET device (11) is connected to the input end of the startup circuit (1), and the source is connected to the source of the N-type MOSFET device (21); during the startup of the power circuit (200), the gate of the first MOSFET device (11) is provided with a high level, and the first MOSFET device (11) is turned on; after the power circuit (200) is started, the gate of the first MOSFET device (11) is provided with a low level, and the first MOSFET device (11) is turned off.

5. The power supply circuit according to claim 4, characterized in that: The gate of the first MOSFET device (11) is connected to the drain of the first MOSFET device (11) via a second resistor (12).

6. The power supply circuit according to claim 3, characterized in that: The startup circuit (1) further comprises a switch device (13), wherein the switch device (13) comprises a second MOSFET device (131), wherein the drain of the second MOSFET device (131) is connected to the gate of the first MOSFET device (11), the source of the second MOSFET device (131) is grounded, and the gate of the second MOSFET device (131) is provided with a corresponding control signal according to the state of the power-consuming circuit (200).

7. The power supply circuit according to claim 6, characterized in that: The switch device (13) further comprises a voltage stabilizing diode (132), wherein a cathode of the voltage stabilizing diode is connected to a drain of the second MOSFET device (131), and an anode of the voltage stabilizing diode is connected to a source of the second MOSFET device (131).

8. A semiconductor device, characterized in that: The semiconductor device comprises: A power circuit (200); and The power supply circuit (100) according to any one of claims 1 to 7, which supplies power to the power consumption circuit (200).

9. A semiconductor device, characterized in that: The semiconductor device comprises: A power-consuming circuit (200) comprises the power supply circuit (100) according to any one of claims 1 to 7, wherein the power supply circuit (100) supplies power to an internal circuit of the power-consuming circuit (200).

10. A switching power supply, characterized in that: The switching power supply comprises: A power supply circuit (3); and The semiconductor device according to claim 8 or 9, which controls the power supply circuit.

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