Short-circuit protection circuit, switching power supply and fire-fighting equipment
By introducing a delay module into the short-circuit protection circuit, the hiccup cycle is extended and power consumption is reduced, which solves the problems of component damage and rapid self-start recovery when the load is short-circuited, and realizes safe and energy-saving short-circuit protection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-25
- Publication Date
- 2026-03-13
AI Technical Summary
Existing short-circuit protection circuits have problems such as direct power loss to the load leading to component damage, short hiccup cycles and high power consumption when the load is short-circuited, making it difficult to achieve rapid self-start recovery.
A short-circuit protection circuit including a drive module, a current detection module, and a delay module was designed. The delay module extends the hiccup cycle, reduces power consumption, and enables rapid self-start recovery when the load returns to normal.
It achieves reduced power consumption and heat generation when the load is short-circuited, and rapid self-start recovery when the load returns to normal, thus improving safety and energy efficiency.
Smart Images
Figure CN223993555U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of circuit technology, and in particular to a short-circuit protection circuit, a switching power supply, and a fire-fighting device. Background Technology
[0002] Short-circuit protection circuits are commonly used in switching power supplies. Existing short-circuit protection circuits employ either a back-end latch-up or a hiccup mode implementation. The drawbacks of back-end latch-up are: direct power loss to the load can easily damage some components, and it cannot automatically restart. The drawbacks of hiccup mode are: when the load is short-circuited, the hiccup cycle is short, resulting in high power consumption and significant load heat generation; upon resumption of operation, the switching power supply struggles to quickly self-start and return to normal operating mode. Therefore, a new technical solution is urgently needed to address the aforementioned technical problems.
[0003] The content of the background section is merely the technology known to the inventor and does not necessarily represent the prior art in this field. Utility Model Content
[0004] To address one or more of the problems existing in the prior art, this utility model provides a short-circuit protection circuit for a switching power supply, the short-circuit protection circuit comprising:
[0005] The drive module has its output terminal connected to the switching power supply to provide a drive signal to the switching power supply; the output terminal of the switching power supply can be connected to a load to supply power to the load.
[0006] A current detection module, which can be connected to the output terminal of the load to detect the output current of the load; and
[0007] The delay module has its input terminal connected to the output terminal of the current detection module and its output terminal connected to the input terminal of the drive module. The delay module can operate based on the output current detected by the current detection module.
[0008] Optionally, the driving module includes a switching transistor and an optocoupler, wherein the gate of the switching transistor is connected to the output terminal of the delay module, the source is connected to the positive terminal of the light-emitting unit of the optocoupler, and the drain and the negative terminal of the light-emitting unit are grounded; the collector of the receiving unit of the optocoupler is connected to a first resistor and the switching power supply, and the emitter is grounded.
[0009] Optionally, the switching transistor includes a P-channel metal-oxide-semiconductor field-effect transistor; the light-emitting unit includes a first diode, which includes a photodiode; and the receiving unit includes a first transistor, which includes a photodiode.
[0010] Optionally, the driving module further includes a second resistor, a third resistor, a fourth resistor, a first capacitor, and a second capacitor, wherein one end of the second resistor is connected to the negative terminal of the light-emitting unit, and the other end is grounded; one end of the third resistor is connected to the positive terminal of the light-emitting unit, and the other end is connected to the fourth resistor, and the other end of the fourth resistor is connected to the output terminal of the delay module; the two ends of the first capacitor are respectively connected in parallel with the collector and emitter of the receiving unit; and the second capacitor is connected in parallel with the second resistor.
[0011] Optionally, the delay module includes a second diode and a third capacitor, wherein the positive terminal of the second diode is connected to the output terminal of the current detection module, the negative terminal is connected to the fourth resistor and one end of the third capacitor, and the other end of the third capacitor is grounded.
[0012] Optionally, the delay module further includes a second transistor, the base of which is connected to the output terminal of the current detection module, the emitter of which is connected to one end of the third capacitor, and the collector of which is grounded.
[0013] Optionally, the current detection module includes a comparator, the positive input of which is connected to the output of the load, the negative input of which is connected to a reference voltage source, and the output of which is connected to the anode of the second diode and the base of the second transistor. When the output current of the load is less than a first threshold, the comparator outputs a low level; the delay module is not triggered; the drive module receives a low level input; the switching transistor is turned on; the optocoupler is turned off; and the drive module outputs a high level, providing a first drive signal to the switching power supply, thus putting the switching power supply into a conducting state.
[0014] Optionally, the current detection module includes a comparator, the positive input of which is connected to the output of the load, the negative input of which is connected to a reference voltage source, and the output of which is connected to the anode of the second diode and the base of the second transistor. When the output current of the load is greater than or equal to a first threshold, the comparator outputs a high level; the delay module is triggered; when the voltage across the third capacitor is less than a second threshold, the third capacitor is charged; the drive module receives a low level input; the switching transistor is turned on; the optocoupler is turned off; and the drive module outputs a high level, which can provide a second drive signal to the switching power supply, the second drive signal being less than the first drive signal, and the switching power supply is in a conducting state.
[0015] Optionally, the current detection module includes a comparator, the positive input of which is connected to the output of the load, the negative input of which is connected to a reference voltage source, and the output of which is connected to the anode of the second diode and the base of the second transistor. When the output current of the load is greater than or equal to a first threshold, the comparator outputs a high level; the delay module is triggered; when the voltage across the third capacitor is greater than or equal to a second threshold, the third capacitor completes charging; the drive module inputs a high level; the switching transistor is turned off; the optocoupler is turned on; the drive module outputs a low level, and the switching power supply is in sleep mode.
[0016] Optionally, the current detection module includes a comparator, the positive input of which is connected to the output of the load, the negative input of which is connected to a reference voltage source, and the output of which is connected to the anode of the second diode and the base of the second transistor. When the switching power supply is in sleep mode, and the output current of the load is less than a first threshold, the comparator outputs a low level. When the voltage across the third capacitor is greater than or equal to a second threshold, the third capacitor is fully charged. The second transistor is turned on. The third capacitor discharges through the second transistor. The driving module inputs a low level. The switching transistor is turned on. The optocoupler is turned off. The driving module outputs a high level, and the switching power supply resumes its on state.
[0017] Optionally, the delay module further includes a fifth resistor and a sixth resistor, wherein one end of the fifth resistor is connected to the positive terminal of the second diode, and the other end is connected to one end of the sixth resistor; the other end of the sixth resistor is connected to the base of the second transistor; and the other end of the fifth resistor and the first end of the sixth resistor are connected to the output terminal of the current detection module.
[0018] Optionally, the current detection module includes a comparator, the positive input of which is connected to the output of the load, the negative input of which is connected to a reference voltage source, and the output of which is connected to the fifth resistor and the sixth resistor.
[0019] Optionally, the current detection module further includes a fourth capacitor, a seventh resistor, an eighth resistor, and a ninth resistor, wherein one end of the fourth capacitor is connected to the positive input terminal of the comparator, and the other end is grounded; one end of the seventh resistor is connected to the output terminal of the load, and the other end is connected to the fourth capacitor and the positive input terminal; one end of the eighth resistor is connected to the reference voltage source, and the other end is connected to the negative input terminal; one end of the ninth resistor is connected to the negative input terminal, and the other end is grounded.
[0020] Optionally, the third capacitor may include an adjustable capacitor.
[0021] This utility model also provides a switching power supply, including: the short-circuit protection circuit as described above.
[0022] This utility model also provides a fire-fighting device, including: a switching power supply as described above, wherein the fire-fighting device includes at least one of a fire detector, an emergency lighting lamp, or a fire alarm.
[0023] This invention's short-circuit protection circuit can operate in hiccup mode. When a short circuit occurs in the load, the delay circuit is triggered, which can prolong the hiccup cycle, reduce power consumption, and decrease heat generation. When the load returns to normal, the delay circuit is not triggered, and the switching power supply can quickly restart and recover. Attached Figure Description
[0024] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings:
[0025] Figure 1 A schematic diagram of a short-circuit protection circuit according to some embodiments of the present invention is shown.
[0026] Figure 2 A circuit diagram of a short-circuit protection circuit according to some embodiments of the present invention is shown.
[0027] Figure 3 A schematic diagram of a switching power supply according to some embodiments of the present invention is shown.
[0028] Figure 4 A schematic diagram of a fire-fighting device according to some embodiments of the present invention is shown. Detailed Implementation
[0029] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this invention. Therefore, the drawings and description are considered exemplary in nature and not restrictive.
[0030] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "multiple" means two or more, unless otherwise explicitly specified.
[0031] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "coupling" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for mutual communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0032] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0033] The following provides many different embodiments or examples for implementing various structures of this invention. To simplify the invention, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.
[0034] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.
[0035] This invention provides a short-circuit protection circuit for a switching power supply. Figure 1 A schematic diagram of a short-circuit protection circuit according to some embodiments of the present invention is shown. Figure 1 As shown, the short-circuit protection circuit 100 includes a drive module 10, a current detection module 20, and a delay module 30. The output of the drive module 10 can be connected to a switching power supply P to provide a drive signal to the switching power supply P. The drive signal may include a pulse width modulation (PWM) signal. The output of the switching power supply P can be connected to a load L to supply power to the load L. The current detection module 20 can be connected to the output of the load L to detect the output current of the load L. The input of the delay module 30 is connected to the output of the current detection module 20. The output of the delay module 30 is connected to the input of the drive module 10. The delay module 30 can operate based on the output current detected by the current detection module 20. This short-circuit protection circuit can operate in a hiccup mode. When a short circuit occurs in the load, the delay circuit is triggered, which can prolong the hiccup cycle, reduce power consumption, and reduce heat generation. When the load returns to normal, the delay circuit is not triggered, and the switching power supply can quickly self-start and recover.
[0036] Figure 2 A circuit diagram of a short-circuit protection circuit according to some embodiments of the present invention is shown. For example... Figure 2As shown, the driving module 10 includes a switching transistor K and an optocoupler U1. The switching transistor K may include a P-channel metal-oxide-semiconductor (PMOS). The optocoupler U1 includes a light-emitting unit and a receiving unit. The light-emitting unit may include a first diode D1. The first diode D1 may include a photodiode. The receiving unit may include a first transistor Q1. The first transistor Q1 may include a photodiode. The gate g of the switching transistor K is connected to the output terminal of the delay module 30, the source s is connected to the positive terminal of the light-emitting unit (e.g., the first diode D1), and the drain d and the negative terminal of the light-emitting unit (e.g., the first diode D1) are grounded. The driving module 10 also includes a first resistor R1. The first resistor R1 is a pull-up resistor connected to the voltage source VCC. The collector c of the receiving unit (e.g., the first transistor Q1) is connected to the first resistor R1 and the switching power supply P, and the emitter e is grounded.
[0037] It should be noted that this description uses an example of a light-emitting unit including a first diode D1 and a receiving unit including a first transistor Q1, but this invention is not limited to this and other similar devices can be used. Furthermore, the optocoupler U1 can be replaced with other similar devices. In practical applications, adjustments can be made as needed, and all of these are within the scope of protection of this invention.
[0038] In some embodiments, such as Figure 2 As shown, the driving module 10 also includes a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, and a second capacitor C2. One end of the second resistor R2 is connected to the negative terminal of the light-emitting unit (e.g., the first diode D1), and the other end is grounded. One end of the third resistor R3 is connected to the positive terminal of the light-emitting unit, and the other end is connected to the fourth resistor R4. The third resistor R3 and the positive terminal of the light-emitting unit are connected to the voltage source VCC. The other end of the fourth resistor R4 is connected to the output terminal of the delay module 30. The two ends of the first capacitor C1 are connected in parallel with the collector c and emitter e of the receiving unit, respectively. The second capacitor C2 is connected in parallel with the second resistor R2.
[0039] In some embodiments, such as Figure 2 As shown, the delay module 30 also includes a second diode D2 and a third capacitor C3. The positive terminal of the second diode D2 is connected to the output terminal of the current detection module 20, and the negative terminal is connected to the fourth resistor R4 and one end of the third capacitor C3. The other end of the third capacitor C3 is grounded.
[0040] In some embodiments, such as Figure 2As shown, the delay module 30 also includes a second transistor Q2. The second transistor Q2 can be a PNP transistor. The base (b) of the second transistor Q2 is connected to the output terminal of the current detection module 20. The emitter (e) of the second transistor Q2 is connected to one end of the third capacitor C3. The collector (c) of the second transistor Q2 is grounded.
[0041] In some embodiments, such as Figure 2 As shown, the current detection module 20 includes a comparator U2. The positive input terminal of comparator U2 is connected to the output terminal of the load L. The negative input terminal of comparator U2 is connected to the reference voltage source Vref. The output terminal of comparator U2 is connected to the anode of the second diode D2 and the base b of the second transistor Q2. Comparator U2 is also connected to the voltage source VCC.
[0042] In some embodiments, such as Figure 2 As shown, the delay module 30 also includes a fifth resistor R5 and a sixth resistor R6. One end of the fifth resistor R5 is connected to the positive terminal of the second diode D2, and the other end is connected to one end of the sixth resistor R6. The other end of the sixth resistor R6 is connected to the base b of the second transistor Q2. The other end of the fifth resistor R5 and one end of the sixth resistor R6 are connected to the output terminal of the current detection module 20. The fifth resistor R5 and the sixth resistor R6 are connected to the output terminal of the comparator U2.
[0043] In some embodiments, such as Figure 2 As shown, the current detection module 20 also includes a fourth capacitor C4, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9. One end of the fourth capacitor C4 is connected to the positive input terminal of comparator U2, and the other end is grounded. One end of the seventh resistor R7 is connected to the output terminal of the load L, and the other end is connected to the fourth capacitor C4 and the positive input terminal of comparator U2. One end of the eighth resistor R8 is connected to the reference voltage source Vref, and the other end is connected to the negative input terminal of comparator U2. One end of the ninth resistor R9 is connected to the negative input terminal of comparator U2, and the other end is grounded.
[0044] The structure of the short-circuit protection circuit 100 has been described above. It should be noted that... Figure 2 In the embodiments described, the switching transistor K is a PMOS transistor and the second transistor Q2 is a PNP transistor, but this invention is not limited thereto. Alternatively, the switching transistor K can be an NMOS transistor, the second transistor Q2 can be an NPN transistor, and other parts of the circuit can be adjusted appropriately. These are all within the protection scope of this invention. It is understood that, although not shown in the figures, the short-circuit protection circuit 100 may also include components such as a housing.
[0045] The working principle of the short-circuit protection circuit 100 is described below.
[0046] The current detection module 10 detects that the output current of the load L is less than the first threshold TH1, indicating that the load L is not short-circuited, i.e., it is in normal mode. The comparator U2 outputs a low level. The delay module 30 is not triggered. The driver module 10 inputs a low level. The switching transistor K is turned on. The optocoupler U1 is turned off. The driver module 10 outputs a high level, providing the first drive signal S1 (with a large duty cycle) to the switching power supply P. The switching power supply P is in the on state and can supply power to the load L normally.
[0047] The current detection module 10 detects that the output current of the load L is greater than or equal to the first threshold TH1, causing a short circuit in the load L. The comparator U2 outputs a high level. The delay module 30 is triggered. The voltage across the third capacitor C3 is less than the second threshold TH2, and the third capacitor C3 begins to charge. While the third capacitor C3 is charging, the drive module 10 still inputs a low level. The switching transistor K remains on. The optocoupler U1 remains off. The drive module 10 still outputs a high level, providing a second drive signal S2 to the switching power supply P. The second drive signal S2 is less than the first drive signal S1, so the switching power supply P remains on and can still supply power to the load L. In other words, when the load L is short-circuited, the delay module 30 is triggered. When the third capacitor C3 of the delay module 30 is charging but not fully charged, the drive module 10 does not immediately stop outputting the drive signal. Instead, it outputs a second drive signal S2 with a small duty cycle to the switching power supply P, keeping the switching power supply P on and supplying power to the load L with a smaller output power. This keeps the load L working while protecting the switching power supply P and the load L from damage.
[0048] As the third capacitor C3 charges, the voltage across it gradually increases. When the voltage across C3 exceeds or equals the second threshold TH2, C3 is fully charged. The driver module 10 inputs a high level. Switch K is turned off. Optocoupler U1 is turned on. The driver module 10 outputs a low level, stopping the drive signal output, and the switching power supply P enters a sleep state. The switching power supply P stops conducting, ceasing power supply to the load L. The third capacitor C3 continues charging, the driver module 10 continues to stop outputting the drive signal, and the switching power supply P remains in a sleep state, continuing to stop supplying power to the load L. This process reduces power consumption and heat generation in both the switching power supply P and the load L, resulting in greater energy efficiency.
[0049] When the switching power supply P is in sleep mode, the output current of the load L is less than the first threshold TH1 (or the load L does not output current). Comparator U2 outputs a low level. The voltage across the third capacitor C3 is greater than or equal to the second threshold TH2. The third capacitor C3 completes charging. The third capacitor C3 triggers the second transistor Q2 to conduct. The third capacitor C3 can discharge through the second transistor Q2. As the third capacitor C3 discharges, the voltage across it gradually decreases until it drops to a certain level (e.g., less than or equal to the third threshold TH3). The input level of the driver module 10 flips, and the driver module 10 becomes a low-level input. Switch K conducts. Optocoupler U1 is turned off. The driver module 10 outputs a high level, and the switching power supply P resumes its conducting state. The driver module 10 can output a first drive signal S1 with a higher duty cycle to the switching power supply P, allowing the switching power supply P to supply power to the load L with a higher output power.
[0050] It should be noted that the first threshold TH1, the second threshold TH2, and the second threshold TH3 are not necessarily related in magnitude and can be adjusted according to actual needs.
[0051] Understandably, the length of the hiccup cycle can be characterized by the length of the sleep time. A longer sleep time results in a longer hiccup cycle, and vice versa. The length of the sleep time is related to the charging speed of the third capacitor C3, which in turn is related to its capacitance. A larger capacitance value results in a slower charging speed, a longer sleep time, and a longer hiccup cycle. Conversely, a smaller capacitance value results in a faster charging speed, a shorter sleep time, and a shorter hiccup cycle.
[0052] It is evident that the length of the hiccup cycle is related to the charging speed of the third capacitor C3. In some embodiments, the third capacitor C3 can be an adjustable capacitor. The capacitance value of the third capacitor C3 can be adjusted to regulate its charging speed, thereby regulating the hiccup cycle. For example, appropriately increasing the capacitance value of the third capacitor C3 can decrease its charging speed, thus prolonging the hiccup cycle. Conversely, appropriately decreasing the capacitance value of the third capacitor C3 can accelerate its charging speed, thus shortening the hiccup cycle.
[0053] This invention's short-circuit protection circuit incorporates a delay module. When a short circuit occurs in the load, the delay module is triggered, and its third capacitor charges. During charging, the drive module can still output a drive signal to the switching power supply, allowing the power supply to continue powering the load. Once the third capacitor is fully charged, the drive module stops outputting drive signals to the switching power supply, which then stops supplying power to the load. This lengthens the short-circuit cycle, reducing power consumption and heat generation, resulting in greater energy efficiency. When the load returns to normal, the delay circuit is not triggered, the drive module's input level flips, and the drive module outputs a drive signal to the switching power supply, enabling the power supply to quickly self-start and resume power supply to the load. Compared to traditional solutions, this invention's short-circuit protection circuit is safer, more energy-efficient, and more intelligent.
[0054] This utility model also provides a switching power supply. Figure 3 A schematic diagram of a switching power supply according to some embodiments of the present invention is shown. For example... Figure 3 As shown, the switching power supply P includes the short-circuit protection circuit 100 as described above.
[0055] This utility model also provides a fire-fighting device. Figure 4 Schematic diagrams of fire-fighting equipment according to some embodiments of the present invention are shown. For example... Figure 4 As shown, the fire protection equipment 200 includes the switching power supply P as described above. The fire protection equipment 200 may include at least one of a fire detector, emergency lighting, or fire alarm. It is not limited to this.
[0056] It should be understood that both the switching power supply P and the fire-fighting equipment 200 can include the short-circuit protection circuit 100 as described above, and therefore both can achieve similar technical effects to the short-circuit protection circuit 100, which will not be elaborated here.
[0057] It should be noted that although several modules of short-circuit protection circuits / switching power supplies / fire-fighting equipment are mentioned in the detailed description above, this division is not mandatory. In fact, according to the embodiments of this utility model, the features and functions of two or more modules described above can be implemented in one module. Conversely, the features and functions of one module described above can be further divided and specified by multiple modules.
[0058] It should be noted that this utility model may only include Figure 1-4 Any one or more features of any one or more embodiments. In other words, not all of the features shown need to be implemented simultaneously in the short-circuit protection circuit / switching power supply / fire protection equipment of this utility model.
[0059] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. A short-circuit protection circuit for a switching power supply, characterized by comprising: The short circuit protection circuit comprises: a driving module, an output end of the driving module being connectable to the switching power supply to provide a driving signal to the switching power supply; an output end of the switching power supply being connectable to a load to supply power to the load; a current detection module, the current detection module being connectable to an output end of the load to detect an output current of the load; and a delay module, an input end of the delay module being connected to an output end of the current detection module, an output end of the delay module being connected to an input end of the driving module, the delay module being operable based on the output current detected by the current detection module; wherein the driving module comprises a switching transistor and an optoelectronic coupler, a gate of the switching transistor being connected to the output end of the delay module, a source of the switching transistor being connected to a positive pole of a light emitting unit of the optoelectronic coupler, a drain of the switching transistor and a negative pole of the light emitting unit being grounded, a collector of a receiving unit of the optoelectronic coupler being connected to a first resistor and the switching power supply, an emitter of the receiving unit being grounded.
2. The short circuit protection circuit according to claim 1, characterized in that The switching transistor comprises a P-channel metal-oxide-semiconductor field effect transistor; the light emitting unit comprises a first diode, the first diode comprising a photosensitive diode; the receiving unit comprises a first triode, the first triode comprising a photosensitive triode.
3. The short circuit protection circuit of claim 1, wherein The driving module further comprises a second resistor, a third resistor, a fourth resistor, a first capacitor and a second capacitor, one end of the second resistor being connected to the negative pole of the light emitting unit, the other end of the second resistor being grounded, one end of the third resistor being connected to the positive pole of the light emitting unit, the other end of the third resistor being connected to the fourth resistor, the other end of the fourth resistor being connected to the output end of the delay module, the first capacitor being connected in parallel to the collector and the emitter of the receiving unit, the second capacitor being connected in parallel to the second resistor.
4. The short circuit protection circuit of claim 3, wherein The delay module comprises a second diode and a third capacitor, a positive pole of the second diode being connected to the output end of the current detection module, a negative pole of the second diode being connected to the fourth resistor and one end of the third capacitor, the other end of the third capacitor being grounded.
5. The short circuit protection circuit of claim 4, wherein The delay module further comprises a second triode, a base of the second triode being connected to the output end of the current detection module, an emitter of the second triode being connected to the one end of the third capacitor, a collector of the second triode being grounded.
6. The short circuit protection circuit of claim 5, wherein The current detection module comprises a comparator, a positive input end of the comparator being connected to the output end of the load, a negative input end of the comparator being connected to a reference voltage source, an output end of the comparator being connected to the positive pole of the second diode and the base of the second triode; when the output current of the load is less than a first threshold value, the comparator outputs a low level; the delay module is not triggered; the driving module inputs a low level; the switching transistor is turned on; the optoelectronic coupler is turned off; the driving module outputs a high level to provide a first driving signal to the switching power supply, the switching power supply being in an on state.
7. The short circuit protection circuit of claim 5, wherein The current detection module comprises a comparator, a positive input end of the comparator is connected with an output end of the load, a negative input end of the comparator is connected with a reference voltage source, and an output end of the comparator is connected with a positive electrode of the second diode and a base of the second triode; when an output current of the load is greater than or equal to a first threshold value, the comparator outputs a high level; the delay module is triggered; when a voltage across the third capacitor is less than a second threshold value, the third capacitor is charged; the driving module inputs a low level; the switch tube is turned on; the photoelectric coupler is turned off; the driving module outputs a high level, a second driving signal smaller than a first driving signal can be provided to the switching power supply, and the switching power supply is in a conducting state.
8. The short circuit protection circuit of claim 5, wherein, The current detection module comprises a comparator, a positive input end of the comparator is connected with an output end of the load, a negative input end of the comparator is connected with a reference voltage source, and an output end of the comparator is connected with a positive electrode of the second diode and a base of the second triode; when an output current of the load is greater than or equal to a first threshold value, the comparator outputs a high level; the delay module is triggered; when a voltage across the third capacitor is less than a second threshold value, the third capacitor is charged; the driving module inputs a low level; the switch tube is turned on; the photoelectric coupler is turned off; the driving module outputs a high level, a second driving signal smaller than a first driving signal can be provided to the switching power supply, and the switching power supply is in a conducting state.
9. The short circuit protection circuit of claim 5, wherein, The current detection module comprises a comparator, a positive input end of the comparator is connected with an output end of the load, a negative input end of the comparator is connected with a reference voltage source, and an output end of the comparator is connected with a positive electrode of the second diode and a base of the second triode; when an output current of the load is greater than or equal to a first threshold value, the comparator outputs a high level; the delay module is triggered; when a voltage across the third capacitor is less than a second threshold value, the third capacitor is charged; the driving module inputs a low level; the switch tube is turned on; the photoelectric coupler is turned off; the driving module outputs a high level, a second driving signal smaller than a first driving signal can be provided to the switching power supply, and the switching power supply is in a conducting state.
10. The short-circuit protection circuit according to any one of claims 5 to 9, characterized in that The delay module further comprises a fifth resistor and a sixth resistor, one end of the fifth resistor is connected with the positive electrode of the second diode, and the other end of the fifth resistor is connected with one end of the sixth resistor; the other end of the sixth resistor is connected with the base of the second triode; the other end of the fifth resistor and the one end of the sixth resistor are connected with an output end of the current detection module.
11. The short circuit protection circuit of claim 10, wherein The current detection module comprises a comparator, a positive input end of the comparator is connected with an output end of the load, a negative input end of the comparator is connected with a reference voltage source, and an output end of the comparator is connected with a positive electrode of the second diode and a base of the second triode; when an output current of the load is greater than or equal to a first threshold value, the comparator outputs a high level; the delay module is triggered; when a voltage across the third capacitor is less than a second threshold value, the third capacitor is charged; the driving module inputs a low level; the switch tube is turned on; the photoelectric coupler is turned off; the driving module outputs a high level, a second driving signal smaller than a first driving signal can be provided to the switching power supply, and the switching power supply is in a conducting state.
12. The short circuit protection circuit of claim 11, wherein The current detection module further comprises a fourth capacitor, a seventh resistor, an eighth resistor and a ninth resistor, one end of the fourth capacitor is connected with the positive input end of the comparator, and the other end of the fourth capacitor is grounded; one end of the seventh resistor is connected with the output end of the load, and the other end of the seventh resistor is connected with the fourth capacitor and the positive input end; One end of the eighth resistor is connected to the reference voltage source, and the other end is connected to the negative input terminal; one end of the ninth resistor is connected to the negative input terminal, and the other end is grounded.
13. The short circuit protection circuit of claim 4, wherein The third capacitor comprises an adjustable capacitor.
14. A switched mode power supply characterized by Comprising: The short-circuit protection circuit according to any one of claims 1-13.
15. A fire fighting apparatus characterized by, Comprising: The switching power supply according to claim 14, wherein the fire-fighting equipment comprises at least one of a fire-fighting detector, an emergency lighting lamp or a fire alarm.