Power supply circuit and electronic equipment

Abstract

The utility model discloses a power supply circuit and electronic equipment, and the power supply circuit comprises a power supply input circuit which is used for outputting a power supply voltage; the surge circuit is connected with the output end of the power input circuit; the buffer circuit is connected with the output end of the power input circuit; the filter circuit is connected with the output end of the buffer circuit, and the output end of the filter circuit is used for supplying power to a load circuit; wherein the buffer circuit comprises at least two switch tubes and a control circuit, the at least two switch tubes are connected in series, the output end of the power supply input circuit is connected with the filter circuit through the at least two switch tubes, and the control circuit is connected with the output end of the power supply input circuit and the at least two switch tubes and used for controlling the at least two switch tubes to be slowly conducted. Through the mode, the voltage surge limiting capability of the power supply circuit is improved, the current impact of surge current on the power supply circuit is relieved, and the voltage endurance capability of the power supply circuit is improved.

Description

Technical Field

[0001] This application relates to the field of power supply technology, and in particular to a power supply circuit and electronic device. Background Technology

[0002] In the daily use of electronic devices, power is typically switched on and off by plugging and unplugging the power cord. These devices often integrate a large number of capacitors. When the power is switched on, a large instantaneous current is generated due to the rapid charging characteristics of the capacitors. This phenomenon is called surge current, and surge current can cause arcing.

[0003] In the existing power supply path, after the power adapter is connected to the device through the power connector, the power is directly supplied to the DC-DC converter of the system's power management integrated circuit or other peripheral circuits after passing through the surge protection circuit.

[0004] For equipment with high power supply voltage, the existing power supply path is not capable enough to limit voltage surges, resulting in excessive surge current impact on the power supply path, causing low withstand voltage of the power supply path and making it prone to arcing at the moment of power-on. Utility Model Content

[0005] The main technical problem this application addresses is to provide a power supply circuit and electronic device that solves the problem of insufficient voltage surge limitation capability of the power supply path, resulting in excessive surge current impact on the power supply path, low withstand voltage capability of the power supply path, and easy arcing at the moment of power-on.

[0006] This application provides a power supply circuit, including:

[0007] Power input circuit, used to output power supply voltage;

[0008] A surge circuit is connected to the output terminal of the power input circuit.

[0009] A buffer circuit is connected to the output terminal of the power input circuit.

[0010] A filter circuit is connected to the output terminal of the buffer circuit, and the output terminal of the filter circuit is used to supply power to the load circuit.

[0011] The buffer circuit includes at least two switching transistors and a control circuit. The at least two switching transistors are connected in series. The output terminal of the power input circuit is connected to the filter circuit through the at least two switching transistors. The control circuit is connected to the output terminal of the power input circuit and the at least two switching transistors respectively, and is used to control the at least two switching transistors to turn on slowly.

[0012] In some embodiments, the at least two switching transistors include a first switching transistor and a second switching transistor. A first terminal of the first switching transistor is connected to the output terminal of the power input circuit, a second terminal of the first switching transistor is connected to the first terminal of the second switching transistor, a second terminal of the second switching transistor is connected to the filter circuit, and the control terminals of the first switching transistor and the second switching transistor are connected to the control circuit.

[0013] In some embodiments, the buffer circuit further includes a preset circuit, one end of which is connected to the output terminal of the power input circuit, and the other end of which is connected to the first terminal of the second switching transistor, for providing a preset voltage to the second switching transistor so that the first switching transistor and the second switching transistor are turned on synchronously.

[0014] In some embodiments, the preset circuit includes a first diode and a first resistor, the cathode of the first diode is connected to the output terminal of the power input circuit, and the anode of the first diode is connected to the first terminal of the second switching transistor through the first resistor.

[0015] In some embodiments, the control circuit includes a second resistor, a third resistor, a fourth resistor, a third switch, a fifth resistor, a sixth resistor, and a first capacitor. One end of the second resistor is connected between the first terminal of the first switch and the output terminal of the power input circuit, and the other end of the second resistor is connected to the control terminal of the second switch. The control terminal of the first switch is connected between the other end of the second resistor and the control terminal of the second switch. One end of the third resistor is connected between the first terminal of the first switch and the output terminal of the power input circuit, and the other end of the third resistor is connected to the first terminal of the third switch through the fourth resistor. The first terminal of the third switch is grounded. The second terminal of the third switch is connected between the third resistor and the fourth resistor through the fifth resistor. The third terminal of the third switch is connected between the control terminal of the second switch and the control terminal of the first switch through the sixth resistor. One end of the first capacitor is connected between the second resistor and the first terminal of the first switch, and the other end of the first capacitor is connected between the second resistor and the control terminal of the first switch.

[0016] In some embodiments, when the power supply circuit is powered on, the third switch is turned on and the first capacitor is charged, so that the first switch and the second switch are slowly turned on.

[0017] In some embodiments, the power supply circuit further includes a discharge circuit, which is connected to the output terminal of the power input circuit, the input terminal of the filter circuit, and the output terminal of the filter circuit, respectively, for discharging the power supply circuit.

[0018] In some embodiments, the discharge circuit includes a seventh resistor, a second diode, an eighth resistor, a ninth resistor, a bidirectional diode, a fourth switch, a tenth resistor, a fifth switch, and an eleventh resistor. One end of the seventh resistor is connected to the output terminal of the power input circuit, and the other end of the seventh resistor is connected to the first terminal of the fourth switch. The second terminal of the fourth switch is grounded. The cathode of the second diode is connected between the seventh resistor and the first terminal of the fourth switch, and the anode of the second diode is connected to the second terminal of the fourth switch. One end of the eighth resistor is connected between the second terminal of the second switch and the input terminal of the filter circuit. The other end is connected between the positive terminal of the second diode and the second terminal of the fourth switch through the ninth resistor. One end of the tenth resistor is connected to the output terminal of the filter circuit, and the other end of the tenth resistor is connected to the first terminal of the fifth switch. The second terminal of the fifth switch is grounded. The third terminal of the fifth switch is connected to one end of the eleventh resistor. The other end of the eleventh resistor is connected between the eighth resistor and the ninth resistor. The third terminal of the fourth switch is connected to the other end of the eleventh resistor. One end of the bidirectional diode is connected to the first terminal of the fourth switch, and the other end of the bidirectional diode is connected to the second terminal of the fourth switch.

[0019] In some embodiments, when the power supply circuit is powered off, the fourth switch is turned off, the fifth switch is turned on, and the power supply circuit discharges through the tenth resistor.

[0020] This application also provides an electronic device including the power supply circuit described above.

[0021] The beneficial effects of this application are as follows: This application provides a power supply circuit and electronic device. The power supply circuit includes: a power input circuit for outputting power supply voltage; a surge circuit connected to the output terminal of the power input circuit; a buffer circuit connected to the output terminal of the power input circuit; and a filter circuit connected to the output terminal of the buffer circuit, the output terminal of which supplies power to the load circuit. The buffer circuit includes at least two switching transistors and a control circuit. The at least two switching transistors are connected in series. The output terminal of the power input circuit is connected to the filter circuit through the at least two switching transistors. The control circuit is connected to both the output terminal of the power input circuit and the at least two switching transistors, and is used to control the at least two switching transistors to conduct slowly. By setting a buffer circuit between the power input circuit and the filter circuit, the power supply circuit's ability to limit voltage surges is improved. By controlling the at least two switching transistors in the buffer circuit to conduct slowly, the current in the power supply circuit rises slowly, mitigating the current impact of surge current on the power supply circuit. The multiple switching transistors further improve the voltage withstand capability of the power supply circuit, effectively reducing the occurrence of arcing at power-on. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0023] Figure 1 This is a circuit diagram of one embodiment of the power supply circuit provided in this application;

[0024] Figure 2 This is a circuit diagram of another embodiment of the power supply circuit provided in this application. Detailed Implementation

[0025] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0027] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0030] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0031] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0032] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a connection between two components or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0033] In the existing power supply path, after the power adapter is connected to the device through the power connector, the power is directly supplied to the DC-DC converter of the system's power management integrated circuit or other peripheral circuits after passing through the surge protection circuit.

[0034] For equipment with high power supply voltage, the existing power supply path is not capable enough to limit voltage surges, resulting in excessive surge current impact on the power supply path, causing low withstand voltage of the power supply path and making it prone to arcing at the moment of power-on.

[0035] Please see Figure 1 As shown, Figure 1 This is a circuit diagram of one embodiment of the power supply circuit provided in this application. The power supply circuit 10 of this embodiment is applied to electronic devices, including but not limited to network video recorders with network power supply capabilities.

[0036] The power supply circuit 10 in this embodiment includes a power input circuit 11, a surge circuit 12, a buffer circuit 13, and a filter circuit 14.

[0037] The power input circuit 11 is used to output the power supply voltage. The power input circuit 11 includes, but is not limited to, a power adapter, such as a power adapter plugged into a socket to output a 48V power supply voltage.

[0038] Surge circuit 12 is connected to the output terminal of power input circuit 11, meaning surge circuit 12 receives the power supply voltage output by power input circuit 11. Surge circuit 12 includes, but is not limited to, surge tubes, used to absorb voltage surges. For example, in this embodiment, surge circuit 12 is surge tube D3, with the negative terminal of surge tube D3 connected to the output terminal of power input circuit 11 and the positive terminal of surge tube D3 grounded.

[0039] The buffer circuit 13 is connected to the output terminal of the power input circuit 11, that is, the buffer circuit 13 receives the power supply voltage output by the power input circuit 11.

[0040] The output of the filter circuit 14 is connected to the output of the buffer circuit 13, and the output of the filter circuit 14 is used to supply power to the load circuit 16. That is, the output voltage of the buffer circuit 13 is filtered by the filter circuit 14 before supplying power to the load circuit 16. The filter circuit 14 includes, but is not limited to, multiple filter capacitors, which can smooth the fluctuations of the output voltage of the buffer circuit 13 and provide a more stable voltage output to the load circuit 16.

[0041] The buffer circuit 13 includes at least two switching transistors 17 and a control circuit 131. The at least two switching transistors 17 are connected in series. The output terminal of the power input circuit 11 is connected to the filter circuit 14 through the at least two switching transistors 17. The control circuit 131 is connected to the output terminal of the power input circuit 11 and the at least two switching transistors 17 respectively, and is used to control the at least two switching transistors 17 to turn on slowly.

[0042] In some embodiments, the buffer circuit 13 includes two switching transistors 17 and a control circuit 131. For example, as... Figure 1 As shown, two switching transistors 17 are connected in series. The two switching transistors 17 are connected to the power input circuit 11 and the filter circuit 14, respectively. The control circuit 131 is connected to both the power input circuit 11 and the two switching transistors 17. Both the two switching transistors 17 and the control circuit 131 receive the power supply voltage output from the power input circuit 11. The control circuit 131 controls the two switching transistors 17 to slowly turn on. At this time, the two switching transistors 17 slowly turn on, and the voltage or current flowing from the power input circuit 11 to the filter circuit 14 slowly increases. Because the two switching transistors 17 have high withstand voltage characteristics, the withstand voltage capability of the power supply circuit 10 is improved.

[0043] In some embodiments, the buffer circuit 13 includes three switching transistors 17 and a control circuit 131. The three switching transistors 17 are connected in series and are respectively connected to the power input circuit 11 and the filter circuit 14. The control circuit 131 is connected to both the power input circuit 11 and the three switching transistors 17. Both the three switching transistors 17 and the control circuit 131 receive the power supply voltage output from the power input circuit 11. The control circuit 131 controls the three switching transistors 17 to conduct slowly. At this time, the three switching transistors 17 conduct slowly, and the voltage or current flowing from the power input circuit 11 to the filter circuit 14 increases slowly, further improving the withstand voltage capability of the power supply circuit 10.

[0044] In other embodiments, the buffer circuit 13 includes a plurality of switching transistors 17 and a control circuit 131, with the plurality of switching transistors 17 connected in series.

[0045] This embodiment improves the ability of the power circuit 10 to limit voltage surges by setting a buffer circuit 13 between the power input circuit 11 and the filter circuit 14. By controlling at least two switching transistors 17 in the buffer circuit 13 to slowly turn on, the current in the power circuit 10 rises slowly, which reduces the current impact of the surge current on the power circuit 10, improves the withstand voltage capability of the power circuit 10, and effectively reduces the occurrence of arcing at the moment of power-on.

[0046] According to some embodiments of this application, such as Figure 1 As shown, the at least two switching transistors 17 in this embodiment include a first switching transistor Q1 and a second switching transistor Q2. The first end of the first switching transistor Q1 is connected to the output end of the power input circuit 11, the second end of the first switching transistor Q1 is connected to the first end of the second switching transistor Q2, the second end of the second switching transistor Q2 is connected to the filter circuit 14, and the control ends of the first switching transistor Q1 and the second switching transistor Q2 are connected to the control circuit 131.

[0047] In some embodiments, the buffer circuit 13 includes a first switch Q1, a second switch Q2, and a control circuit 131. The first switch Q1 and the second switch Q2 are connected in series, and the control circuit 131 is connected to the output terminal of the power input circuit 11, the control terminal of the first switch Q1, and the control terminal of the second switch Q2, respectively.

[0048] In some embodiments, the first terminal of the first switch Q1 receives the power supply voltage output by the power input circuit 11, and the control terminal of the first switch Q1 receives the output voltage of the control circuit 131, so the first switch Q1 is slowly turned on; at this time, the first terminal of the second switch Q2 receives the output voltage of the second terminal of the first switch Q1, and the control terminal of the second switch Q2 receives the output voltage of the control circuit 131, so the second switch Q2 is slowly turned on, and the power supply voltage slowly enters the filter circuit 14 through the second terminal of the second switch Q2.

[0049] In this embodiment, at least two switching transistors 17 include a first switching transistor Q1 and a second switching transistor Q2, and the first switching transistor Q1 and the second switching transistor Q2 are connected in series. The first switching transistor Q1 and the second switching transistor Q2 share the power supply voltage. At this time, the withstand voltage capability of the power supply circuit 10 is the sum of the withstand voltages of the first switching transistor Q1 and the second switching transistor Q2, thereby improving the overall withstand voltage capability of the power supply circuit 10.

[0050] In this embodiment, the control terminals of the first switch Q1 and the second switch Q2 are both connected to the control circuit 131, so that the first switch Q1 and the second switch Q2 can be controlled by the control circuit 131 to conduct slowly. By controlling the first switch Q1 and the second switch Q2 to conduct slowly, the rate of current rise in the power supply circuit 10 is further slowed down, thereby reducing the current surge and protecting the subsequent filter circuit 14 and load circuit 16 from damage.

[0051] According to some embodiments of this application, the buffer circuit 13 further includes a preset circuit 132. One end of the preset circuit 132 is connected to the output terminal of the power input circuit 11, and the other end of the preset circuit 132 is connected to the first terminal of the second switch Q2, for providing a preset voltage to the second switch Q2 so that the first switch Q1 and the second switch Q2 are turned on synchronously.

[0052] In some embodiments, the first switch Q1 receives the power supply voltage output by the power input circuit 11, and the second switch Q2 obtains a preset voltage through the preset circuit 132. The first switch Q1 and the second switch Q2 are turned on synchronously.

[0053] In this embodiment, a preset voltage is provided for the second switch Q2 through the setting of the preset circuit 132, so as to realize the synchronous conduction of the first switch Q1 and the second switch Q2. The first switch Q1 and the second switch Q2 can jointly withstand the impact of power supply voltage surge.

[0054] According to some embodiments of this application, such as Figure 2 As shown, the preset circuit 132 in this embodiment includes a first diode D1 and a first resistor R1. The cathode of the first diode D1 is connected to the output terminal of the power input circuit 11, and the anode of the first diode D1 is connected to the first terminal of the second switch Q2 through the first resistor R1.

[0055] Optionally, the first diode D1 is a Zener diode, and the first resistor R1 is a current-limiting resistor.

[0056] In some embodiments, the first terminal of the first switch Q1 receives the power supply voltage output by the power input circuit 11, and the first terminal of the second switch Q2 receives the power supply voltage through the first diode D1 and the first resistor R1. The control terminals of the first switch Q1 and the second switch Q2 both receive the output voltage of the control circuit 131. At this time, since the first terminal of the second switch Q2 can receive a preset voltage through the first diode D1 and the first resistor R1, the first switch Q1 and the second switch Q2 can be synchronously turned on.

[0057] In this embodiment, both the first switch Q1 and the second switch Q2 are P-type MOSFETs. The control terminals of the first switch Q1 and the second switch Q2 are the gates, the first terminals of the first switch Q1 and the second switch Q2 are the sources, and the second terminals of the first switch Q1 and the second switch Q2 are the drains. In other embodiments, the first switch Q1 and the second switch Q2 can be other types of switches, such as transistors.

[0058] In this embodiment, by setting the first diode D1 and the first resistor R1, a preset voltage is provided for the second switch Q2, so that the first switch Q1 and the second switch Q2 are turned on synchronously. This allows the first switch Q1 and the second switch Q2 to jointly withstand the impact of the power supply voltage surge, reducing the possibility of the first switch Q1 and the second switch Q2 being damaged by the high voltage surge, thereby protecting the subsequent filter circuit 14 and load circuit 16 from damage.

[0059] According to some embodiments of this application, such as Figure 1 As shown, the control circuit 131 in this embodiment includes a second resistor R2, a third resistor R3, a fourth resistor R4, a third switch Q3, a fifth resistor R5, a sixth resistor R6, and a first capacitor C1.

[0060] One end of the second resistor R2 is connected between the first terminal of the first switch Q1 and the output terminal of the power input circuit 11. The other end of the second resistor R2 is connected to the control terminal of the second switch Q2. The control terminal of the first switch Q1 is connected between the other end of the second resistor R2 and the control terminal of the second switch Q2. One end of the third resistor R3 is connected between the first terminal of the first switch Q1 and the output terminal of the power input circuit 11. The other end of the third resistor R3 is connected to the first terminal of the third switch Q3 through the fourth resistor R4. The first terminal of the third switch Q3 is grounded. The second terminal of the third switch Q3 is connected between the third resistor R3 and the fourth resistor R4 through the fifth resistor R5. The third terminal of the third switch Q3 is connected between the control terminal of the second switch Q2 and the control terminal of the first switch Q1 through the sixth resistor R6. One end of the first capacitor C1 is connected between the second resistor R2 and the first terminal of the first switch Q1. The other end of the first capacitor C1 is connected between the second resistor R2 and the control terminal of the first switch Q1.

[0061] According to some embodiments of this application, when the power supply circuit 10 is powered on, the third switch Q3 is turned on and the first capacitor C1 is charged, so that the first switch Q1 and the second switch Q2 are turned on slowly.

[0062] When the power supply circuit 10 is powered on, the power input circuit 11 outputs the power supply voltage.

[0063] In some embodiments, when the power supply circuit 10 is powered on, the first switch Q1 and the second switch Q2 are in the off state; the third switch Q3 in the control circuit 131 receives the voltage divided by the third resistor R3 and the fourth resistor R4, and the third switch Q3 is turned on; the voltage is output to the control terminals of the first switch Q1 and the second switch Q2 through the sixth resistor R6; the first capacitor C1 is charged, and a voltage difference is generated between the first terminal of the first switch Q1 and the control terminal of the first switch Q1, and a voltage difference is also generated between the first terminal of the second switch Q2 and the control terminal of the second switch Q2. At this time, due to the presence of the first capacitor C1, the first switch Q1 and the second switch Q2 slowly generate a voltage difference, so that the first switch Q1 and the second switch Q2 slowly turn on.

[0064] In this embodiment, the third switch Q3 is an NPN transistor, with its first terminal being the emitter, its second terminal being the base, and its third terminal being the collector. In other embodiments, the third switch Q3 can be other types of switches, such as a MOSFET.

[0065] The first switch Q1 and the second switch Q2 are slowly turned on, the power supply circuit 10 is slowly turned on, and the current flowing to the filter circuit 14 is slowly increased. Furthermore, the conduction speed of the power supply circuit 10 can be changed by adjusting the parameters of the first capacitor C1 and the sixth resistor R6, thereby pulling down the power supply voltage output by the power input circuit 11 and avoiding arcing.

[0066] In this embodiment, by turning on the third switch Q3 and charging the first capacitor C1, the control circuit 131 controls the first switch Q1 and the second switch Q2 to turn on slowly. The power supply circuit 10 turns on slowly, and the current flowing to the filter circuit 14 rises slowly, thereby reducing the current surge.

[0067] According to some embodiments of this application, please refer to Figure 2 As shown, Figure 2 This is a circuit diagram of another embodiment of the power supply circuit provided in this application. The power supply circuit 10 in this embodiment also includes a discharge circuit 15, which is connected to the output terminal of the power input circuit 11, the input terminal of the filter circuit 14, and the output terminal of the filter circuit 14, respectively, for discharging the power supply circuit 10.

[0068] In some embodiments, see Figures 1-2 As shown, the filter circuit 14 includes multiple capacitors, resulting in a large capacitance value and a large amount of stored energy in the power supply circuit 10. When the power supply circuit 10 is powered off and then powered on again, the power supply circuit 10 may malfunction due to residual voltage. Here, residual voltage refers to the residual voltage that still exists in the power supply circuit 10 and is maintained for a period of time after the power supply circuit 10 is powered off due to the slow discharge characteristics of the capacitors.

[0069] In this embodiment, the discharge circuit 15 is connected to the output terminal of the power input circuit 11, the input terminal of the filter circuit 14, and the output terminal of the filter circuit 14, respectively, which can ensure that the energy stored in the power circuit 10 is quickly released when the power circuit 10 is powered off, reducing the impact of residual power.

[0070] According to some embodiments of this application, such as Figure 2 As shown, the discharge circuit 15 in this embodiment includes a seventh resistor R7, a second diode D2, an eighth resistor R8, a ninth resistor R9, a bidirectional diode D, a fourth switch Q4, a tenth resistor R10, a fifth switch Q5, and an eleventh resistor R11.

[0071] One end of the seventh resistor R7 is connected to the output terminal of the power input circuit 11, and the other end of the seventh resistor R7 is connected to the first terminal of the fourth switch Q4. The second terminal of the fourth switch Q4 is grounded. The cathode of the second diode D2 is connected between the seventh resistor R7 and the first terminal of the fourth switch Q4, and the anode of the second diode D2 is connected to the second terminal of the fourth switch Q4. One end of the eighth resistor R8 is connected between the second terminal of the second switch Q2 and the input terminal of the filter circuit 14, and the other end of the eighth resistor R8 is connected through the ninth resistor R9 to the anode of the second diode D2 and the first terminal of the fourth switch Q4. Between the two terminals, one end of the tenth resistor R10 is connected to the output terminal of the filter circuit 14, and the other end of the tenth resistor R10 is connected to the first terminal of the fifth switch Q5. The second terminal of the fifth switch Q5 is grounded, and the third terminal of the fifth switch Q5 is connected to one end of the eleventh resistor R11. The other end of the eleventh resistor R11 is connected between the eighth resistor R8 and the ninth resistor R9. The third terminal of the fourth switch Q4 is connected to the other end of the eleventh resistor R11. One end of the bidirectional diode D is connected to the first terminal of the fourth switch Q4, and the other end of the bidirectional diode D is connected to the second terminal of the fourth switch Q4.

[0072] Optionally, the second diode D2 is a Zener diode, and the bidirectional diode D is a bidirectional transient voltage suppressor diode.

[0073] According to some embodiments of this application, when the power supply circuit 10 is powered off, the fourth switch Q4 is turned off, the fifth switch Q5 is turned on, and the power supply circuit 10 discharges through the tenth resistor R10.

[0074] When the power supply circuit 10 is powered off, the power input circuit 11 stops outputting power voltage.

[0075] In some embodiments, the seventh resistor R7 and the second diode D2 are connected in series to form a clamping circuit, and the eighth resistor R8 and the ninth resistor R9 are used for voltage division. When the power supply circuit 10 is powered off, the fourth switch Q4 is turned off, and the voltage divided by the eighth resistor R8 and the ninth resistor R9 is output to the third terminal of the fifth switch Q5, and the fifth switch Q5 is turned on; at this time, the power supply circuit 10 discharges through the tenth resistor R10.

[0076] In this embodiment, the fourth switch Q4 is an N-type MOSFET, with its first terminal serving as the gate, its second terminal as the source, and its third terminal as the drain. The fifth switch Q5 is an NPN transistor, with its first terminal serving as the collector, its second terminal as the emitter, and its third terminal as the base. In other embodiments, the fourth switch Q4 can be other types of switches, such as transistors; and the fifth switch Q5 can be other types of switches, such as MOSFETs.

[0077] Furthermore, when the power supply circuit 10 is powered on, the first terminal of the fourth switch Q4 is powered through the front end of the switch 17 of the buffer circuit 13, and the voltage is divided by the eighth resistor R8 and the ninth resistor R9 and output to the third terminal of the fourth switch Q4, so the fourth switch Q4 is turned on and the fifth switch Q5 is turned off.

[0078] In this embodiment, the discharge circuit 15, through the coordinated operation of the fourth switch Q4 and the fifth switch Q5, enables the power supply circuit 10 to discharge rapidly through the tenth resistor R10 when the power supply circuit 10 is powered off, thereby reducing the damage of residual electricity to the power supply circuit 10 and improving the reliability of the power supply circuit 10.

[0079] According to some embodiments of this application, such as Figures 1-2 As shown, the filter circuit 14 in this embodiment includes a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a twelfth resistor R12, and a sixth capacitor C6.

[0080] Among them, one end of the second capacitor C2 is connected to the output terminal of the buffer circuit 13, and the other end of the second capacitor C2 is grounded; one end of the third capacitor C3 is connected to one end of the second capacitor C2, and the other end of the third capacitor C3 is connected to the other end of the second capacitor C2; one end of the fourth capacitor C4 is connected to one end of the third capacitor C3, and the other end of the fourth capacitor C4 is connected to the other end of the third capacitor C3; one end of the fifth capacitor C5 is connected to one end of the fourth capacitor C4 and the load circuit 16, and the other end of the fifth capacitor C5 is connected to the other end of the fourth capacitor C4; one end of the twelfth resistor R12 is connected between the fifth capacitor C5 and the load circuit 16, and the other end of the twelfth resistor R12 is grounded through the sixth capacitor C6.

[0081] This application also provides an electronic device, which includes, but is not limited to, a network video recorder with network power supply capability. The electronic device in this embodiment includes the power supply circuit 10 described in the above embodiment, and will not be repeated here.

[0082] In summary, this application improves the ability of the power circuit 10 to limit voltage surges by setting a buffer circuit 13 between the power input circuit 11 and the filter circuit 14. By controlling at least two switching transistors 17 in the buffer circuit 13 to slowly turn on, the current in the power circuit 10 rises slowly, which reduces the current impact of the surge current on the power circuit 10, improves the withstand voltage capability of the power circuit 10, and effectively reduces the occurrence of arcing at the moment of power-on.

[0083] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A power supply circuit, characterized in that, include: Power input circuit, used to output power supply voltage; A surge circuit is connected to the output terminal of the power input circuit. A buffer circuit is connected to the output terminal of the power input circuit. A filter circuit is connected to the output terminal of the buffer circuit, and the output terminal of the filter circuit is used to supply power to the load circuit. The buffer circuit includes at least two switching transistors and a control circuit. The at least two switching transistors are connected in series. The output terminal of the power input circuit is connected to the filter circuit through the at least two switching transistors. The control circuit is connected to the output terminal of the power input circuit and the at least two switching transistors respectively, and is used to control the at least two switching transistors to turn on slowly.

2. The power supply circuit according to claim 1, characterized in that, The at least two switching transistors include a first switching transistor and a second switching transistor. The first end of the first switching transistor is connected to the output end of the power input circuit. The second end of the first switching transistor is connected to the first end of the second switching transistor. The second end of the second switching transistor is connected to the filter circuit. The control ends of the first switching transistor and the second switching transistor are connected to the control circuit.

3. The power supply circuit according to claim 2, characterized in that, The buffer circuit further includes a preset circuit, one end of which is connected to the output terminal of the power input circuit, and the other end of which is connected to the first terminal of the second switching transistor, for providing a preset voltage to the second switching transistor so that the first switching transistor and the second switching transistor are turned on synchronously.

4. The power supply circuit according to claim 3, characterized in that, The preset circuit includes a first diode and a first resistor. The cathode of the first diode is connected to the output terminal of the power input circuit, and the anode of the first diode is connected to the first terminal of the second switching transistor through the first resistor.

5. The power supply circuit according to any one of claims 1-4, characterized in that, The control circuit includes a second resistor, a third resistor, a fourth resistor, a third switch, a fifth resistor, a sixth resistor, and a first capacitor. One end of the second resistor is connected between the first terminal of the first switch and the output terminal of the power input circuit. The other end of the second resistor is connected to the control terminal of the second switch. The control terminal of the first switch is connected between the other end of the second resistor and the control terminal of the second switch. One end of the third resistor is connected between the first terminal of the first switch and the output terminal of the power input circuit. The other end of the third resistor is connected to the first terminal of the third switch through the fourth resistor. The first terminal of the third switch is grounded. The second terminal of the third switch is connected between the third resistor and the fourth resistor through the fifth resistor. The third terminal of the third switch is connected between the control terminal of the second switch and the control terminal of the first switch through the sixth resistor. One end of the first capacitor is connected between the second resistor and the first terminal of the first switch. The other end of the first capacitor is connected between the second resistor and the control terminal of the first switch.

6. The power supply circuit according to claim 5, characterized in that, When the power supply circuit is powered on, the third switch is turned on, and the first capacitor is charged, so that the first switch and the second switch are slowly turned on.

7. The power supply circuit according to any one of claims 1-4, characterized in that, The power supply circuit also includes a discharge circuit, which is connected to the output terminal of the power input circuit, the input terminal of the filter circuit, and the output terminal of the filter circuit, respectively, for discharging the power supply circuit.

8. The power supply circuit according to claim 7, characterized in that, The discharge circuit includes a seventh resistor, a second diode, an eighth resistor, a ninth resistor, a bidirectional diode, a fourth switch, a tenth resistor, a fifth switch, and an eleventh resistor. One end of the seventh resistor is connected to the output terminal of the power input circuit, and the other end of the seventh resistor is connected to the first terminal of the fourth switch. The second terminal of the fourth switch is grounded. The cathode of the second diode is connected between the seventh resistor and the first terminal of the fourth switch, and the anode of the second diode is connected to the second terminal of the fourth switch. One end of the eighth resistor is connected between the second terminal of the second switch and the input terminal of the filter circuit, and the other end of the eighth resistor is connected to... The ninth resistor is connected between the positive terminal of the second diode and the second terminal of the fourth switch. One end of the tenth resistor is connected to the output terminal of the filter circuit, and the other end of the tenth resistor is connected to the first terminal of the fifth switch. The second terminal of the fifth switch is grounded. The third terminal of the fifth switch is connected to one end of the eleventh resistor, and the other end of the eleventh resistor is connected between the eighth resistor and the ninth resistor. The third terminal of the fourth switch is connected to the other end of the eleventh resistor. One end of the bidirectional diode is connected to the first terminal of the fourth switch, and the other end of the bidirectional diode is connected to the second terminal of the fourth switch.

9. The power supply circuit according to claim 8, characterized in that, When the power supply circuit is powered off, the fourth switch is turned off, the fifth switch is turned on, and the power supply circuit discharges through the tenth resistor.

10. An electronic device, characterized in that, Includes the power supply circuit as described in any one of claims 1-9.

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