Overcurrent protection circuit and switching power supply

Abstract

The invention provides an overcurrent protection circuit and a switching power supply. The overcurrent protection circuit comprises a direct current output circuit, a switching control circuit and a short circuit detection circuit, the input end of the direct-current output circuit is connected with the power supply circuit, and the output end of the direct-current output circuit is connected with a load; the switch control power supply is connected with the direct-current output circuit and is used for controlling the on and off of the direct-current output circuit; the short circuit detection circuit is connected with the DC output circuit, the switch control power supply and the load. When the load is short-circuited, the short-circuit detection circuit is switched on, and the switch control circuit is switched off so as to control the direct-current output circuit to be switched off. Over-current protection is carried out through the over-current protection circuit, so that the response speed can be improved while the influence of short-circuit current on the switching power supply is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to an overcurrent protection circuit and a switching power supply. Background Art

[0002] In the circuit system, the switching power supply is used to supply power to the load. When the load is short-circuited, it will cause irreversible effects on the switching power supply, and even burn the power supply. If the switching power supply supplies power to multiple loads at the same time, when one of the loads is short-circuited, it is easy to cause other loads to go out of service one after another. Therefore, the current switching power supply usually has an overcurrent protection mechanism. When the load goes out of service, the overcurrent protection mechanism is used to protect the switching power supply to prevent the current from affecting the switching power supply. However, the commonly used overcurrent protection mechanism is software-type overcurrent protection, that is, by adjusting the duty cycle of the PWM signal to limit the current output by the switching power supply to achieve overcurrent protection. However, the software-type overcurrent protection has a slow response speed and may not be able to provide overcurrent protection to the switching power supply in time. Summary of the invention

[0003] The present invention provides an overcurrent protection circuit and a switching power supply, aiming to solve the problem of slow response speed of the current overcurrent protection mechanism.

[0004] In a first aspect, the present invention provides an overcurrent protection circuit, which includes a DC output circuit, a switch control circuit and a short-circuit detection circuit; the input end of the DC output circuit is connected to the power supply circuit, and the output end of the DC output circuit is connected to the load; the switch control power supply is connected to the DC output circuit to control the conduction and shutdown of the DC output circuit; the short-circuit detection circuit is respectively connected to the DC output circuit, the switch control power supply and the load; wherein, when the load is short-circuited, the short-circuit detection circuit is turned on, and the switch control circuit is turned off to control the DC output circuit to be turned off.

[0005] Furthermore, the DC output circuit includes a filter circuit and a first switch tube; one end of the filter circuit is connected to the power supply circuit, the other end of the filter circuit is connected to the first pole of the first switch tube, the second pole of the first switch tube is connected to the load, and the controlled pole of the first switch tube is connected to the switch control circuit.

[0006] Furthermore, the filtering circuit includes a first diode, a first capacitor and a second capacitor; the positive electrode of the first diode is connected to the power supply circuit, the negative electrode of the first diode is respectively connected to one end of the first capacitor, the first electrode of the first switch tube, the switch control circuit and the short-circuit detection circuit, and the other end of the first capacitor is grounded; one end of the second capacitor is connected to the second electrode of the first switch tube, and the other end of the second capacitor is grounded.

[0007] Furthermore, the switch control circuit includes a second switch tube and an energy storage circuit; the first pole of the second switch tube is grounded, the second pole of the second switch tube is connected to the controlled pole of the first switch tube, the controlled pole of the second switch tube is connected to the energy storage circuit, and the energy storage circuit is connected to the filter circuit.

[0008] Furthermore, the energy storage circuit includes a third capacitor, and the third capacitor is connected to the controlled electrode of the second switch tube.

[0009] Furthermore, the energy storage circuit also includes a first resistor, a second resistor, a third resistor and a fourth resistor; one end of the first resistor is connected to the second capacitor, the other end of the first resistor is respectively connected to one end of the second resistor and one end of the third resistor, and the other end of the second resistor is connected to the short-circuit detection circuit; the other end of the third resistor is respectively connected to the short-circuit detection circuit and one end of the fourth resistor, and the other end of the fourth resistor is connected to the controlled electrode of the second switch tube.

[0010] Furthermore, the short-circuit detection circuit includes a third switch tube and a fourth switch tube; the first pole of the third switch tube is connected to the filter circuit, the second pole of the third switch tube is connected to the controlled pole of the fourth switch tube, the controlled pole of the third switch tube is connected to the energy storage circuit, the first pole of the fourth switch tube is grounded, and the second pole of the fourth switch tube is connected to the energy storage circuit.

[0011] Furthermore, the short-circuit detection circuit also includes a second diode and a first light-emitting diode; the anode of the second diode is connected to the load, the cathode of the second diode is connected to the cathode of the first light-emitting diode, and the anode of the first light-emitting diode is connected to the controlled electrode of the third switch tube.

[0012] Furthermore, the short-circuit detection circuit also includes a fifth resistor and a sixth resistor; one end of the fifth resistor is connected to the second pole of the third switch tube, and the other end of the fifth resistor is connected to the controlled pole of the fourth switch tube; one end of the sixth resistor is connected to the load, and the other end of the sixth resistor is connected to the positive pole of the second diode.

[0013] In a second aspect, the present invention further provides a switching power supply, comprising a power supply circuit and any one of the overcurrent protection circuits described above.

[0014] The invention discloses a switching power supply. The switching power supply comprises a power supply circuit and an overcurrent protection circuit. The overcurrent protection circuit comprises a DC output circuit, a switch control circuit and a short-circuit detection circuit. The DC output circuit is respectively connected to the power supply circuit and the load. When the DC output circuit is turned on, the power supply circuit supplies power to the load through the DC output circuit. The switch control circuit is connected to the DC output circuit and is used to control the turning on and off of the DC output circuit. The short-circuit detection circuit is respectively connected to the DC output circuit and the switch control circuit and is used to detect whether a short circuit occurs in the load. When a short circuit occurs in the load, the short-circuit detection circuit is turned on, and then the switch control circuit is controlled to be turned off. The switch control circuit then controls the DC output circuit to be turned off, thereby cutting off the connection between the power supply circuit and the load, avoiding the short-circuit current from affecting the power supply circuit. Furthermore, overcurrent protection can be achieved through a hardware circuit, thereby improving the response speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0016] Figure 1 is a block diagram of an overcurrent protection circuit provided by a first embodiment of the present invention;

[0017] Figure 2 is a block diagram of an overcurrent protection circuit provided by a second embodiment of the present invention;

[0018] Figure 3 is a block diagram of an overcurrent protection circuit provided by a third embodiment of the present invention;

[0019] Figure 4 is a circuit diagram of an overcurrent protection circuit provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, operations, elements, components and / or groups thereof.

[0022] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, the singular forms of "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It should also be further understood that the term "and / or" used in the specification of the present invention and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0023] In addition, the directional terms mentioned in the present invention, such as "upper", "lower", "front", "back", "left", "right", "inner", "outer", "side", etc., are only for reference to the directions of the attached drawings and the use status of the product. Therefore, the directional terms used are used to illustrate and understand the present invention, but not to limit the present invention. In addition, in the drawings, structures with similar or identical structures are represented by the same reference numerals.

[0024] See also Figures 1 to 4 , Figure 1 is a block diagram of an overcurrent protection circuit 100 provided in a first embodiment of the present invention; Figure 2 is a block diagram of an overcurrent protection circuit 100 provided in a second embodiment of the present invention; Figure 3 is a block diagram of an overcurrent protection circuit 100 provided in a third embodiment of the present invention; Figure 4 1 is a circuit diagram of an overcurrent protection circuit 100 provided in one embodiment of the present invention. Figure 1 The present invention provides an overcurrent protection circuit 100, which includes a DC output circuit 10, a switch control circuit 20 and a short circuit detection circuit 30; the input end of the DC output circuit 10 is connected to the power supply circuit 200, and the output end of the DC output circuit 10 is connected to the load 300; the switch control power supply is connected to the DC output circuit 10 to control the on and off of the DC output circuit 10; the short circuit detection circuit 30 is respectively connected to the DC output circuit 10, the switch control power supply and the load 300; wherein, when the load 300 is short-circuited, the short circuit detection circuit 30 is turned on, and the switch control circuit 20 is turned off to control the DC output circuit 10 to be turned off.

[0025] Specifically, the overcurrent protection circuit 100 can be applied to a power supply circuit, and is used to provide overcurrent protection for the power supply circuit when a short circuit occurs in a load 300 connected to the power supply circuit, so as to prevent the power supply circuit from being affected by the short circuit current. The overcurrent protection circuit 100 may include a DC output circuit 10, a switch control circuit 20, and a short circuit detection circuit 30, wherein the input end of the DC output circuit 10 is connected to the power supply circuit 200, and the output end of the DC output circuit 10 is connected to the load 300. It can be understood that the power supply circuit 200 is used to supply power to the load 300, and can be a power supply circuit 200 commonly used in the art, and its specific circuit structure is not limited here. The output end of the DC output circuit 10 is connected to the load 300, and the number of the loads 300 connected thereto can be one or more, depending on the specific power supply circuit type and the actual application scenario. When the DC output circuit 10 is turned on, the power supply circuit 200 and the load 300 form a loop, and the load 300 is powered by the DC output circuit 10. When the DC output circuit 10 is turned off, the loop between the power supply circuit 200 and the load 300 is disconnected, and the power supply circuit 200 stops outputting current.

[0026] The switch control circuit 20 is connected to the DC output circuit 10 and is used to control the on and off of the DC output circuit 10. When the switch control circuit 20 is on, the DC output circuit 10 is on, and the power supply circuit 200 supplies power to the load 300 through the DC output circuit 10. When the switch control circuit 20 is off, the DC output circuit 10 is off, and the connection between the power supply circuit 200 and the load 300 is disconnected, thereby preventing the short-circuit current of the load 300 from affecting the power supply.

[0027] The short-circuit detection circuit 30 is respectively connected to the DC output circuit 10, the switch control circuit 20 and the load 300, and is used to detect whether the load 300 is short-circuited, and when the load 300 is short-circuited, a corresponding action is performed. The number of loads 300 connected to the short-circuit detection circuit 30 can be one or more. For example, when the short-circuit detection circuit 30 is connected to only one load 300, it is used to detect whether the load 300 is short-circuited, and when the load 300 is short-circuited, a corresponding action is performed. When the short-circuit detection circuit 30 is connected to multiple loads 300 at the same time, it is used to perform short-circuit detection on the connected loads 300, and when any one of the connected loads 300 is short-circuited, a corresponding action is performed.

[0028] In actual use, the power supply circuit 200 is connected to the load 300 through the DC output circuit 10. When the load 300 works normally, the switch control circuit 20 is in an on state, so that the DC output circuit 10 is also in an on state. The power supply circuit 200 supplies power to the load 300 through the DC output circuit 10. When a short circuit occurs in the load 300, the short circuit detection circuit 30 detects that the load 300 has a short circuit, and the short circuit detection circuit 30 is turned on, thereby controlling the switch control circuit 20 to turn off. After the switch control circuit 20 is turned off, the DC output circuit 10 is turned off accordingly, thereby disconnecting the power supply circuit 200 from the load 300, thereby preventing the load 300 current from affecting the power supply circuit 200.

[0029] As a further embodiment, the DC output circuit 10 includes a filter circuit 11 and a first switch tube 12; one end of the filter circuit 11 is connected to the power supply circuit 200, the other end of the filter circuit 11 is connected to the first electrode of the first switch tube 12, the second electrode of the first switch tube 12 is connected to the load 300, and the controlled electrode of the first switch tube 12 is connected to the switch control circuit 20. As a further embodiment, the filter circuit 11 includes a first diode D1, a first capacitor C1 and a second capacitor C2; the positive electrode of the first diode D1 is connected to the power supply circuit 200, the negative electrode of the first diode D1 is respectively connected to one end of the first capacitor C1, the first electrode of the first switch tube 12, the switch control circuit 20 and the short circuit detection circuit 30, and the other end of the first capacitor C1 is grounded; one end of the second capacitor C2 is connected to the second electrode of the first switch tube 12, and the other end of the second capacitor C2 is grounded.

[0030] The DC output circuit 10 may include a filter circuit 11 and a first switch tube 12. The filter circuit 11 is connected to the power supply circuit 200 and the first pole of the first switch tube 12, respectively, and is used to filter the current input by the power supply circuit 200 to provide a smooth DC output. The first switch tube 12 is used to control the on and off of the DC output circuit 10. The second pole of the first switch tube 12 is connected to the load 300. When the first switch tube 12 is turned on, the filter circuit 11 is connected to the load 300. When the first switch tube 12 is turned off, the filter circuit 11 is disconnected from the load 300. The on and off of the first switch tube 12 is controlled by the switch control circuit 20, that is, when the switch control circuit 20 is turned on, the first switch tube 12 is turned on, and when the switch control circuit 20 is turned off, the first switch tube 12 is turned off.

[0031] like Figure 4As shown, VDD is the output terminal of the power supply circuit 200, and the filter circuit 11 may include a first diode D1 and a first capacitor C1, wherein the positive electrode of the first diode D1 is connected to the power supply circuit 200, and the negative electrode of the first diode D1 is connected to one end of the first capacitor C1 and the first electrode of the first switch tube 12, and the first diode D1 and the first capacitor C1 are used to filter the current to provide a smooth DC output. The first switch tube 12 may be a first transistor Q1, wherein the emitter of the first transistor Q1 is connected to the negative electrode of the first diode D1, the collector of the first transistor Q1 is connected to the load 300, and the controlled electrode of the first transistor Q1 is connected to the switch control circuit 20.

[0032] As a further embodiment, the switch control circuit 20 includes a second switch tube 22 and a tank circuit 21; the first electrode of the second switch tube 22 is grounded, the second electrode of the second switch tube 22 is connected to the controlled electrode of the first switch tube 12, the controlled electrode of the second switch tube 22 is connected to the tank circuit 21, and the tank circuit 21 is connected to the filter circuit 11. As a further embodiment, the tank circuit 21 includes a third capacitor C3, and the third capacitor C3 is connected to the controlled electrode of the second switch tube 22. As a further embodiment, the energy storage circuit 21 also includes a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4; one end of the first resistor R1 is connected to the third capacitor C3, the other end of the first resistor R1 is respectively connected to one end of the second resistor R2 and one end of the third resistor R3, and the other end of the second resistor R2 is connected to the short-circuit detection circuit 30; the other end of the third resistor R3 is respectively connected to the short-circuit detection circuit 30 and one end of the fourth resistor R4, and the other end of the fourth resistor R4 is connected to the controlled pole of the second switch tube 22.

[0033] The switch control circuit 20 may include a second switch tube 22 and a storage circuit 21. The storage circuit 21 is connected to the filter circuit 11. When the power supply circuit 200 inputs current, the storage circuit 21 starts to charge. When the storage circuit 21 is full, the second switch tube 22 is saturated and turned on. The second electrode of the second switch tube 22 is connected to the controlled electrode of the first switch tube 12, and is used to control the on and off of the first switch tube 12. When the second switch tube 22 is saturated and turned on, the first switch tube 12 is turned on, and the power supply circuit 200 supplies power to the load 300. When the second switch tube 22 is turned off, the first switch tube 12 is turned off, and the power supply circuit 200 is disconnected from the load 300.

[0034] like Figure 4As shown, the energy storage circuit 21 may include a third capacitor C3, a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4. The second switch tube 22 may be a second transistor Q2. One end of the third capacitor C3 is connected to the first resistor R1, and the first resistor R1 is respectively connected to the second resistor R2 and the filter circuit 11. When the current of the power supply circuit 200 is input, the filter circuit 11 filters the current, and the third capacitor C3 starts to charge until it is fully charged. At the same time, the third capacitor C3 is directly connected to the base of the second transistor Q2 on the one hand, and is connected to the base of the second transistor Q2 via the third resistor R3 and the fourth resistor R4 on the other hand. When the third capacitor C3 is fully charged, the voltage of the third capacitor C3 is directly given to the base of the second transistor Q2 on the one hand, and is given to the base of the second transistor Q2 via the third resistor R3 and the fourth resistor R4 on the other hand. The second transistor Q2 is saturated and turned on. When the second transistor Q2 is saturated and turned on, the first transistor Q1 is saturated and turned on, and the filter circuit 11 provides a smooth DC current for the load 300.

[0035] As a further embodiment, the short-circuit detection circuit 30 includes a third switch tube and a fourth switch tube; the first electrode of the third switch tube is connected to the filter circuit 11, the second electrode of the third switch tube is connected to the controlled electrode of the fourth switch tube, the controlled electrode of the third switch tube is connected to the energy storage circuit 21, the first electrode of the fourth switch tube is grounded, and the second electrode of the fourth switch tube is connected to the energy storage circuit 21. As a further embodiment, the short-circuit detection circuit 30 also includes a second diode D2 and a first light-emitting diode ZD1; the anode of the second diode D2 is connected to the load 300, the cathode of the second diode D2 is connected to the cathode of the first light-emitting diode ZD1, and the anode of the first light-emitting diode ZD1 is connected to the controlled electrode of the third switch tube Q3. As a further embodiment, the short-circuit detection circuit 30 also includes a fifth resistor R5 and a sixth resistor R6; one end of the fifth resistor R5 is connected to the second pole of the third switch tube, and the other end of the fifth resistor R5 is connected to the controlled pole of the fourth switch tube; one end of the sixth resistor R6 is connected to the load 300, and the other end of the sixth resistor R6 is connected to the positive pole of the second diode D2.

[0036] Among them, the short circuit detection circuit 30 may include a third switch tube and a fourth switch tube, the first electrode of the third switch tube is connected to the filter circuit 11, the second electrode of the third switch tube is connected to the controlled electrode of the fourth switch tube, the controlled electrode of the third switch tube is connected to the energy storage circuit 21, the first electrode of the fourth switch tube is grounded, and the second electrode of the fourth switch tube is connected to the energy storage circuit 21. At the same time, the first light-emitting diode ZD1 and the second diode D2 are connected in series, and the positive electrode of the first light-emitting diode ZD1 is connected to the controlled electrode of the third switch tube, the positive electrode of the second diode D2 is connected to the sixth resistor R6, and the sixth resistor R6 is connected to the load 300. When the load 300 is short-circuited, the third switch tube is turned on, and the current of the filter circuit 11 is output to the controlled electrode of the fourth switch tube through the third switch tube. The fourth switch tube is turned on, so that the second switch tube 22 changes from saturated conduction to off, and then the first switch tube 12 is turned off, and the connection between the filter circuit 11 and the load 300 is disconnected.

[0037] like Figure 4 As shown, the third switch tube can be a third triode Q3, and the fourth switch tube can be a fourth triode Q4, then the emitter of the third triode Q3 is connected to the filter circuit 11, the collector of the third triode Q3 is connected to the base of the fourth triode Q4, the base of the third triode Q3 is connected to the second resistor R2 and the first light-emitting diode ZD1, the emitter of the fourth triode Q4 is grounded, and the collector of the fourth triode Q4 is connected to the third resistor R3. When the load 300 is short-circuited, the voltage difference between the second capacitor C2 and the first resistor R1 is greater than the sum of the conduction voltage of the third triode Q3 and the working voltage of the second diode D2, and the DC output of the first capacitor C1 forms a loop through the second resistor R2, the first light-emitting diode ZD1, the second diode D2, the sixth resistor R6 and the ground, and the base of the third triode Q3 is at a low level, so the third triode Q3 is saturated and turned on. At this time, the output current of the first capacitor C1 flows into the base of the fourth triode Q4 through the third triode Q3, and the fourth triode Q4 is turned on, so that the second triode Q2 changes from on to off, and then the first triode Q1 is turned off, disconnecting the connection between the first capacitor C1 and the load 300. In addition, the second diode D2 is a voltage regulator, and different types of second diodes D2 can be selected to match different power supply voltages.

[0038] The present invention also provides a switching power supply, which includes a power supply circuit 200 and an overcurrent protection circuit 100 according to any one of the above embodiments. The overcurrent protection circuit 100 includes a DC output circuit 10, a switch control circuit 20, and a short circuit detection circuit 30; the input end of the DC output circuit 10 is connected to the power supply circuit 200, and the output end of the DC output circuit 10 is connected to the load 300; the switch control power supply is connected to the DC output circuit 10 to control the on and off of the DC output circuit 10; the short circuit detection circuit 30 is respectively connected to the DC output circuit 10, the switch control power supply, and the load 300; wherein, when the load 300 is short-circuited, the short circuit detection circuit 30 is turned on, and the switch control circuit 20 is turned off to control the DC output circuit 10 to be turned off.

[0039] Specifically, the overcurrent protection circuit 100 can be applied to a power supply circuit, and is used to provide overcurrent protection for the power supply circuit when a short circuit occurs in a load 300 connected to the power supply circuit, so as to prevent the power supply circuit from being affected by the short circuit current. The overcurrent protection circuit 100 may include a DC output circuit 10, a switch control circuit 20, and a short circuit detection circuit 30, wherein the input end of the DC output circuit 10 is connected to the power supply circuit 200, and the output end of the DC output circuit 10 is connected to the load 300. It can be understood that the power supply circuit 200 is used to supply power to the load 300, and can be a power supply circuit 200 commonly used in the art, and its specific circuit structure is not limited here. The output end of the DC output circuit 10 is connected to the load 300, and the number of the loads 300 connected thereto can be one or more, depending on the specific power supply circuit type and the actual application scenario. When the DC output circuit 10 is turned on, the power supply circuit 200 and the load 300 form a loop, and the load 300 is powered by the DC output circuit 10. When the DC output circuit 10 is turned off, the loop between the power supply circuit 200 and the load 300 is disconnected, and the power supply circuit 200 stops outputting current.

[0040] The switch control circuit 20 is connected to the DC output circuit 10 and is used to control the on and off of the DC output circuit 10. When the switch control circuit 20 is on, the DC output circuit 10 is on, and the power supply circuit 200 supplies power to the load 300 through the DC output circuit 10. When the switch control circuit 20 is off, the DC output circuit 10 is off, and the connection between the power supply circuit 200 and the load 300 is disconnected, thereby preventing the short-circuit current of the load 300 from affecting the power supply.

[0041] The short-circuit detection circuit 30 is respectively connected to the DC output circuit 10, the switch control circuit 20 and the load 300, and is used to detect whether the load 300 is short-circuited, and when the load 300 is short-circuited, a corresponding action is performed. The number of loads 300 connected to the short-circuit detection circuit 30 can be one or more. For example, when the short-circuit detection circuit 30 is connected to only one load 300, it is used to detect whether the load 300 is short-circuited, and when the load 300 is short-circuited, a corresponding action is performed. When the short-circuit detection circuit 30 is connected to multiple loads 300 at the same time, it is used to perform short-circuit detection on the connected loads 300, and when any one of the connected loads 300 is short-circuited, a corresponding action is performed.

[0042] In actual use, the power supply circuit 200 is connected to the load 300 through the DC output circuit 10. When the load 300 works normally, the switch control circuit 20 is in an on state, so that the DC output circuit 10 is also in an on state. The power supply circuit 200 supplies power to the load 300 through the DC output circuit 10. When a short circuit occurs in the load 300, the short circuit detection circuit 30 detects that the load 300 has a short circuit, and the short circuit detection circuit 30 is turned on, thereby controlling the switch control circuit 20 to turn off. After the switch control circuit 20 is turned off, the DC output circuit 10 is turned off accordingly, thereby disconnecting the power supply circuit 200 from the load 300, thereby preventing the load 300 current from affecting the power supply circuit 200.

[0043] The overcurrent protection circuit disclosed in the present invention has a DC output circuit connected to a power supply circuit and a load respectively. When the DC output circuit is turned on, the power supply circuit supplies power to the load through the DC output circuit. The switch control circuit is connected to the DC output circuit and is used to control the on and off of the DC output circuit. The short-circuit detection circuit is connected to the DC output circuit and the switch control circuit respectively and is used to detect whether a short circuit occurs in the load. When a short circuit occurs in the load, the short-circuit detection circuit is turned on and then controls the switch control circuit to be turned on. The switch control circuit then controls the DC output circuit to be turned off, thereby cutting off the connection between the power supply circuit and the load, avoiding the short-circuit current from affecting the power supply circuit. Furthermore, overcurrent protection can be implemented through a hardware circuit, thereby improving the response speed.

[0044] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. An overcurrent protection circuit, characterized in that: include: A DC output circuit, wherein an input end of the DC output circuit is connected to a power supply circuit, and an output end of the DC output circuit is connected to a load; A switch control circuit, wherein the switch control power supply is connected to the DC output circuit and is used to control the on and off of the DC output circuit; A short-circuit detection circuit, wherein the short-circuit detection circuit is respectively connected to the DC output circuit, the switch control power supply and the load; Wherein, when the load is short-circuited, the short-circuit detection circuit is turned on, and the switch control circuit is turned off to control the DC output circuit to be turned off.

2. The overcurrent protection circuit according to claim 1, characterized in that: The DC output circuit includes a filter circuit and a first switch tube; One end of the filter circuit is connected to the power supply circuit, the other end of the filter circuit is connected to the first pole of the first switch tube, the second pole of the first switch tube is connected to the load, and the controlled pole of the first switch tube is connected to the switch control circuit.

3. The overcurrent protection circuit according to claim 2, characterized in that: The filter circuit includes a first diode, a first capacitor and a second capacitor; The anode of the first diode is connected to the power supply circuit, the cathode of the first diode is respectively connected to one end of the first capacitor, the first electrode of the first switch tube, the switch control circuit and the short circuit detection circuit, and the other end of the first capacitor is grounded; One end of the second capacitor is connected to the second electrode of the first switch tube, and the other end of the second capacitor is grounded.

4. The overcurrent protection circuit according to claim 2, characterized in that: The switch control circuit includes a second switch tube and an energy storage circuit; The first electrode of the second switch tube is grounded, the second electrode of the second switch tube is connected to the controlled electrode of the first switch tube, the controlled electrode of the second switch tube is connected to the energy storage circuit, and the energy storage circuit is connected to the filter circuit.

5. The overcurrent protection circuit according to claim 4, characterized in that: The energy storage circuit includes a third capacitor, and the third capacitor is connected to the controlled electrode of the second switch tube.

6. The overcurrent protection circuit according to claim 5, characterized in that: The energy storage circuit further includes a first resistor, a second resistor, a third resistor and a fourth resistor; One end of the first resistor is connected to the second capacitor, the other end of the first resistor is respectively connected to one end of the second resistor and one end of the third resistor, and the other end of the second resistor is connected to the short-circuit detection circuit; The other end of the third resistor is connected to the short-circuit detection circuit and one end of the fourth resistor respectively, and the other end of the fourth resistor is connected to the controlled electrode of the second switch tube.

7. The overcurrent protection circuit according to claim 4, characterized in that: The short circuit detection circuit includes a third switch tube and a fourth switch tube; The first electrode of the third switch tube is connected to the filter circuit, the second electrode of the third switch tube is connected to the controlled electrode of the fourth switch tube, the controlled electrode of the third switch tube is connected to the energy storage circuit, the first electrode of the fourth switch tube is grounded, and the second electrode of the fourth switch tube is connected to the energy storage circuit.

8. The overcurrent protection circuit according to claim 7, characterized in that: The short circuit detection circuit also includes a second diode and a first light emitting diode; The anode of the second diode is connected to the load, the cathode of the second diode is connected to the cathode of the first light-emitting diode, and the anode of the first light-emitting diode is connected to the controlled electrode of the third switch tube.

9. The overcurrent protection circuit according to claim 8, characterized in that: The short circuit detection circuit also includes a fifth resistor and a sixth resistor; One end of the fifth resistor is connected to the second electrode of the third switch tube, and the other end of the fifth resistor is connected to the controlled electrode of the fourth switch tube; One end of the sixth resistor is connected to the load, and the other end of the sixth resistor is connected to the anode of the second diode.

10. A switching power supply, characterized in that: The switching power supply comprises a power supply circuit and an overcurrent protection circuit as claimed in any one of claims 1 to 9.

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