Protection device of switching power supply and control method thereof

Abstract

The invention provides a protection device of a switching power supply and a control method thereof. The protection device comprises a protection circuit and a control module, the protection circuit comprises a charging circuit, a voltage clamping circuit and a switching circuit. The charging circuit is used for charging based on input electric signals of the switching power supply; the voltage clamping circuit is used for clamping the voltage of the output end of the charging circuit to a first voltage when the driving signal of the switching power supply is at a low level; the switching circuit is used for outputting a protection signal to the control module when the voltage at the output end of the charging circuit is greater than a first preset voltage threshold; the first voltage is smaller than a first preset voltage threshold; the first preset voltage threshold value is the maximum voltage reached by the voltage of the output end of the charging circuit within the first preset time; the control module stops outputting the driving signal based on the protection signal. The protection device of the switching power supply can avoid the saturation problem of a magnetic device caused by an overlarge duty ratio, and improves the safety of a circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies, and in particular to a protection device for a switching power supply and a control method thereof. Background Art

[0002] In the design of small and medium power supplies, PWM (Pulse Width Modulation) power supply circuits such as BUCK, BOOST, forward, and flyback have been widely used due to their high efficiency, small size, fast response, flexible adjustment, and high safety.

[0003] Although switching power supplies can achieve efficient and flexible energy conversion through PWM control, when the input and output regulation changes rapidly, there is a risk of overshoot in the duty cycle, which leads to saturation of magnetic devices and reduced circuit safety. Summary of the Invention

[0004] The embodiment of the present invention provides a protection device for a switching power supply and a control method thereof, so as to solve the problem of overshoot of the duty cycle of a driving signal of the switching power supply.

[0005] In a first aspect, an embodiment of the present invention provides a protection device for a switching power supply, comprising: a protection circuit and a control module; the protection circuit comprising a charging circuit, a voltage clamping circuit, and a switching circuit; a first end of the voltage clamping circuit connected to a signal output end of the control module, an input end of the charging circuit connected to an input end of the switching power supply, an output end of the charging circuit and a second end of the voltage clamping circuit both connected to an input end of the switching circuit, and an output end of the switching circuit connected to an input end of the control module;

[0006] The charging circuit is used to obtain an input electrical signal of the switching power supply and perform charging based on the input electrical signal;

[0007] The voltage clamping circuit is used to obtain the driving signal output by the control module to the switching power supply, and clamp the output terminal voltage of the charging circuit to a first voltage when the driving signal is at a low level;

[0008] The switch circuit is configured to output a protection signal to the control module when the voltage at the output terminal of the charging circuit is greater than a first preset voltage threshold; the first voltage is less than the first preset voltage threshold; the first preset voltage threshold is the maximum voltage reached by the output terminal of the charging circuit within a first preset time; and the first preset time is the maximum on-time limit of the drive signal;

[0009] The control module stops outputting a driving signal to the switching power supply based on the protection signal.

[0010] In a possible implementation, the charging circuit includes a charging capacitor, a first diode, and a resistance unit;

[0011] The positive electrode of the first diode is the input end of the charging circuit, the negative electrode of the first diode is connected to the first end of the resistance unit, the second end of the resistance unit is connected to the first end of the charging capacitor, the second end of the charging capacitor is grounded, and the first end of the charging capacitor is the output end of the charging circuit.

[0012] In a possible implementation, the resistance unit includes at least one resistor, and each resistor is connected in series between a first end and a second end of the resistance unit.

[0013] In a possible implementation, the resistance unit includes a sliding resistor.

[0014] In a possible implementation, the voltage clamping circuit includes a second diode;

[0015] The cathode of the second diode is the first end of the voltage clamping circuit, and the anode of the second diode is the second end of the voltage clamping circuit.

[0016] In a possible implementation, the switch circuit includes a first switch tube unit and a second switch tube unit;

[0017] The first end of the first switch tube unit is the input end of the switch circuit, the second end of the first switch tube unit is connected to the first end of the second switch tube unit, and the third end of the first switch tube unit is used to receive a first power signal;

[0018] The second end of the second switch tube unit is used to receive a second power supply signal, and the third end of the second switch tube unit is the output end of the switch circuit.

[0019] In a possible implementation, the first switch tube unit includes a first triode and a third diode;

[0020] The base of the first transistor is the first end of the first switching tube unit, the collector of the first transistor is the second end of the first switching tube unit, and the emitter of the first transistor is the third end of the first switching tube unit; the anode of the third diode is connected to the base of the first transistor, and the cathode of the third diode is connected to the collector of the first transistor.

[0021] In a possible implementation, the second switch tube unit includes a second triode, a first resistor, a second resistor, a third resistor, and a fourth diode;

[0022] The first end of the first resistor is the first end of the second switching tube unit, the second end of the first resistor is respectively connected to the cathode of the fourth diode, the base of the second transistor and the first end of the second resistor, the second end of the second resistor is connected to the collector of the second transistor, and the emitter of the second transistor and the anode of the fourth diode are both connected to the first end of the third resistor; the collector of the second transistor is the second end of the second switching tube unit, and the second end of the third resistor is the third end of the second switching tube unit.

[0023] In a second aspect, an embodiment of the present invention provides a method for controlling a protection device of a switching power supply, which is applied to the protection device of the switching power supply as described in the first aspect above, comprising:

[0024] Obtaining a maximum on-time limit of a driving signal of the switching power supply;

[0025] The capacitance of the charging capacitor and the resistance of the resistance unit in the charging circuit are determined according to the maximum on-time limit and the first power signal input to the first switch unit.

[0026] In one possible implementation, determining the capacitance of the charging capacitor and the resistance of the resistance unit in the charging circuit according to the maximum on-time limit and the first power signal input to the first switching unit includes:

[0027] According to the formula Determining the capacitance of the charging capacitor and the resistance of the resistor unit in the charging circuit;

[0028] Among them, t on-max represents the maximum on-time limit, R represents the resistance of the resistor unit, C represents the capacitance of the charging capacitor, Vc represents the voltage of the charging capacitor, and V represents the voltage of the first power signal.

[0029] An embodiment of the present invention provides a protection device for a switching power supply, comprising: a protection circuit and a control module; the protection circuit comprising a charging circuit, a voltage clamping circuit, and a switching circuit; the charging circuit is configured to obtain an input electrical signal from the switching power supply and charge the power supply based on the input electrical signal; the voltage clamping circuit is configured to obtain a drive signal output by the control module to the switching power supply and, when the drive signal is at a low level, clamp the output voltage of the charging circuit to a first voltage; the switching circuit is configured to output a protection signal to the control module when the output voltage of the charging circuit exceeds a first preset voltage threshold; the first voltage is less than the first preset voltage threshold; the first preset voltage threshold is the maximum voltage reached by the output voltage of the charging circuit within a first preset time; the first preset time is the maximum on-time limit of the drive signal; and the control module stops outputting the drive signal to the switching power supply based on the protection signal. The protection device for the switching power supply can shut off the drive signal when the on-time of the drive signal controlling the switching power supply reaches the maximum on-time limit, thereby avoiding magnetic device saturation caused by an excessive duty cycle and improving circuit safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 1 is a schematic structural diagram of a protection device for a switching power supply provided by an embodiment of the present invention;

[0031] Figure 2 is a schematic structural diagram of a protection circuit provided by an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of an implementation flow of a control method for a protection device of a switching power supply provided by an embodiment of the present invention;

[0033] Figure 4 It is a structural diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] To help those skilled in the art better understand this solution, the following will clearly describe the technical solutions in the embodiments of this solution in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of this solution, not all of it. Based on the embodiments of this solution, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of this solution.

[0035] Throughout the specification, claims, and accompanying figures of this solution, the term "including" and any variations thereof mean "including, but not limited to," and are intended to cover non-exclusive inclusions and are not limited to the examples listed herein. Furthermore, the terms "first" and "second," etc., are used to distinguish between different objects, not to describe a specific order.

[0036] The following is a detailed description of the implementation of the present invention with reference to the accompanying drawings:

[0037] In the field of small and medium-power power supply design, PWM switching power supplies are widely used in various electronic devices due to their numerous advantages. However, when input and output regulation changes rapidly, there is a risk of overshoot in the duty cycle of the drive signal, which can cause a series of serious damage to the circuit.

[0038] Duty cycle overshoot first negatively impacts magnetic components like inductors and transformers, causing them to enter a deep saturation state. For example, when the duty cycle exceeds a safety threshold, the current in the inductor continues to increase. The magnetic flux in the inductor is proportional to the current. As the current continues to increase, the magnetic flux also increases. When the magnetic flux reaches a certain level, the inductor's core enters a saturated state. In this saturated state, the inductor's inductance drops dramatically, making it unable to effectively store and release energy. Once the inductor reaches saturation, the current in the circuit increases dramatically and uncontrollably. This not only significantly increases power consumption and reduces power conversion efficiency, but can also cause irreversible damage to other critical components in the circuit. Therefore, duty cycle overshoot in switching power supplies is an urgent issue that needs to be addressed.

[0039] To address the issue of duty cycle overshoot, existing technologies use software algorithms to adjust the duty cycle to avoid overshoot. These algorithms require real-time monitoring and analysis of the circuit's operating status, placing high demands on processor performance. If the processor's computational speed is insufficient, it will be unable to process the large amount of monitoring data in a timely manner, resulting in delays in the execution of the software algorithm. In some applications requiring high real-time performance, this delay can prevent duty cycle overshoot from being corrected in a timely manner, impacting circuit operation.

[0040] An embodiment of the present invention provides a protection device for a switching power supply. The protection device of the switching power supply is charged by an input electrical signal of the switching power supply and determines the allowable charging time based on a maximum on-time limit. When the duty cycle of the drive signal is too large, the protection mechanism of the protection circuit is triggered to stop driving the control chip, thereby avoiding the problem of duty cycle overshoot.

[0041] Specifically, Figure 1 This is a schematic diagram of the structure of a protection device for a switching power supply provided by an embodiment of the present invention. Figure 1The switching power supply protection device includes: a protection circuit 10, a switching power supply 20 and a control module 30; the protection circuit 10 includes a charging circuit 11, a voltage clamping circuit 12 and a switching circuit 13; a first end of the voltage clamping circuit 12 is connected to a signal output end of the control module 30, an input end of the charging circuit 11 is connected to an input end of the switching power supply 20, an output end of the charging circuit 11 and a second end of the voltage clamping circuit 12 are both connected to an input end of the switching circuit 13, and an output end of the switching circuit 13 is connected to an input end of the control module 30;

[0042] The charging circuit 11 is used to obtain an input electrical signal from the switching power supply 20 and perform charging based on the input electrical signal;

[0043] The voltage clamping circuit 12 is used to obtain the driving signal output by the control module 30 to the switching power supply 20, and clamp the output voltage of the charging circuit 11 to a first voltage when the driving signal is at a low level;

[0044] The switch circuit 13 is configured to output a protection signal to the control module 30 when the output voltage of the charging circuit 11 is greater than a first preset voltage threshold; the first voltage is less than the first preset voltage threshold; the first preset voltage threshold is the maximum voltage reached by the output voltage of the charging circuit 11 within a first preset time; and the first preset time is the maximum on-time limit of the driving signal;

[0045] The control module 30 stops outputting the driving signal to the switching power supply 20 based on the protection signal.

[0046] The core structure of the switching power supply protection device proposed in the present invention mainly consists of two key parts: a protection circuit 10 and a control module 30. These two parts work together to ensure the stable operation and efficient work of the switching power supply.

[0047] The protection circuit 10 plays a crucial role as a safety guard in the entire switching power supply protection device. It primarily comprises a charging circuit 11, a voltage clamping circuit 12, and a switching circuit 13. The input of the charging circuit 11 is connected to the input of the switching power supply 20, and is responsible for receiving the input electrical signal from the switching power supply 20 and using this signal to perform charging operations. The first end of the voltage clamping circuit 12 is connected to the signal output of the control module 30, and its second end is connected to the output of the charging circuit 11. When the drive signal output by the control module 30 to the switching power supply 20 is at a low level, the voltage clamping circuit 12 can quickly take effect and stably clamp the output voltage of the charging circuit 11 to a first voltage. This first voltage can ensure that the switching circuit 13 is not turned on. When the drive signal output by the control module 30 to the switching power supply 20 is at a high level, the input electrical signal continues to charge the charging circuit 11 until the output voltage of the charging circuit 11 is greater than a first preset voltage threshold. Then, a protection signal is output to the control module 30. At this time, the charging duration is exactly the maximum on-time limit of the duty cycle. That is, if the duty cycle of the drive signal exceeds the maximum on-time limit, it is protected, thereby ensuring that the duty cycle of the drive signal does not overshoot and improving circuit safety.

[0048] The voltage clamping circuit 12 may include an NMOS transistor or a voltage regulator diode.

[0049] The control module 30 is the brain of the entire switching power supply protection device. It can not only output the driving signal and accurately control the working state of the switching power supply 20, but also make a quick judgment when receiving the protection signal from the switching circuit 13 and stop outputting the driving signal to the switching power supply 20.

[0050] The switching power supply 20, as the core energy conversion unit of the switching power supply, is responsible for efficiently converting the input electrical energy. It can flexibly output power under the precise control of the drive signal output by the control module 30. The protection circuit 10 can provide a maximum duty cycle limit for PWM-type switching power supplies 20, such as buck, boost, forward, and flyback. The drive signal for the switching power supply 20 controlled by the control module 30 can be a PWM signal or a pulse signal such as a PFM (Pulse Frequency Modulation) signal.

[0051] In this embodiment, the control module 30 includes a control chip and a waveform generator. The control chip is used to generate a control signal based on the output voltage set value and the actual output voltage value of the switching power supply 20. The control signal is usually the duty cycle value of the drive signal, and the control signal is sent to the waveform generator. The waveform generator generates a PWM wave based on the control signal and sends the PWM wave to the switching power supply 20 to control the opening and closing of each switching tube in the switching power supply 20.

[0052] As can be seen from the above embodiment, the protection device of the switching power supply provided in this embodiment can turn off the driving signal when the on-time of the driving signal controlling the switching power supply 20 reaches the maximum on-time limit, thereby avoiding the saturation problem of the magnetic device caused by an excessively large duty cycle and improving circuit safety.

[0053] In one possible implementation, Figure 2 FIG. 4 shows a specific circuit diagram of the protection circuit provided in this embodiment, such as Figure 2 As shown, the charging circuit 11 includes a charging capacitor C29, a first diode D16 and a resistance unit;

[0054] The anode of the first diode D16 is the input end of the charging circuit 11, the cathode of the first diode D16 is connected to the first end of the resistance unit, the second end of the resistance unit is connected to the first end of the charging capacitor C29, the second end of the charging capacitor C29 is grounded, and the first end of the charging capacitor C29 is the output end of the charging circuit 11.

[0055] Specifically, when the input electrical signal from the switching power supply 20 is input to the charging circuit 11, the positive electrode of the first diode D16 serves as the input terminal of the charging circuit 11, allowing current to pass through, while the negative electrode is connected to the first end of the resistor unit. Because the first diode D16 has unidirectional conductivity, it only allows current to flow from the positive electrode to the negative electrode, thereby ensuring the unidirectional flow of the charging current. The second end of the resistor unit is connected to the first end of the charging capacitor C29, and the second end of the charging capacitor C29 is grounded. During this process, the input electrical signal charges the charging capacitor C29 through the first diode D16 and the resistor unit, causing the charging capacitor C29 to gradually store energy.

[0056] In one possible implementation, Figure 2 As shown, the resistance unit includes at least one resistor, and each resistor is connected in series between the first end and the second end of the resistance unit.

[0057] Specifically, the resistance unit includes at least one resistor, and these resistors (R26, R27, R28) can be connected in series between the first end and the second end of the resistance unit. Different resistance values ​​will have different effects on the charging process. If the resistance value is large, the charging current will be relatively small, and the charging speed will be slow; conversely, if the resistance value is small, the charging current will be large, and the charging speed will be accelerated.

[0058] In a possible implementation, the resistance unit includes a sliding resistor.

[0059] In this embodiment, by setting a sliding resistor, this embodiment can adapt to more switching power supply scenarios. After the control chip obtains the duty cycle of the drive signal, the required resistance value can be calculated according to the duty cycle, thereby adjusting the sliding resistor to the corresponding resistance value, thereby improving the adaptability of the protection device structure of the switching power supply provided by the present invention.

[0060] In one possible implementation, Figure 2 As shown, the voltage clamping circuit 12 includes a second diode D13;

[0061] The cathode of the second diode D13 is the first end of the voltage clamping circuit 12 , and the anode of the second diode D13 is the second end of the voltage clamping circuit 12 .

[0062] In this embodiment, when the drive signal output by the control module 30 to the switching power supply 20 is at a low level, the second diode D13 is turned on. Due to the conduction characteristics of the diode, the voltage across it remains substantially constant. At this time, the output voltage of the charging circuit 11 is clamped to the conduction voltage of the second diode D13, i.e., the first voltage. When selecting the second diode D13, ensure that the conduction voltage of the second diode D13 is less than the first preset voltage threshold, thereby ensuring that the switching circuit 13 is not turned on when the drive signal is at a low level.

[0063] In a possible implementation, the switch circuit 13 includes a first switch tube unit and a second switch tube unit;

[0064] The first end of the first switch tube unit is the input end of the switch circuit 13, the second end of the first switch tube unit is connected to the first end of the second switch tube unit, and the third end of the first switch tube unit is used to receive a first power signal;

[0065] The second end of the second switch tube unit is used to receive a second power supply signal, and the third end of the second switch tube unit is the output end of the switch circuit 13 .

[0066] In one possible implementation, Figure 2 As shown, the first switch tube unit includes a first transistor N2 and a third diode D12;

[0067] The base of the first transistor N2 is the first end of the first switching tube unit, the collector of the first transistor N2 is the second end of the first switching tube unit, and the emitter of the first transistor N2 is the third end of the first switching tube unit; the anode of the third diode D12 is connected to the base of the first transistor N2, and the cathode of the third diode D12 is connected to the collector of the first transistor N2.

[0068] In a possible implementation, the second switching tube unit includes a second triode P4, a first resistor R29, a second resistor R30, a third resistor R31 and a fourth diode D14;

[0069] The first end of the first resistor R29 is the first end of the second switching tube unit, the second end of the first resistor R29 is respectively connected to the cathode of the fourth diode D14, the base of the second transistor P4 and the first end of the second resistor R30, the second end of the second resistor R30 is connected to the collector of the second transistor P4, the emitter of the second transistor P4 and the anode of the fourth diode D14 are both connected to the first end of the third resistor R31; the collector of the second transistor P4 is the second end of the second switching tube unit, and the second end of the third resistor R31 is the third end of the second switching tube unit.

[0070] Specifically, refer to Figure 2 When the drive signal is high, the high-level voltage is greater than the voltage at point A, and the second diode D13 is turned off. At this time, the voltage at point A gradually increases as the input electrical signal charges the charging capacitor C29 through the three resistors R26, R27, and R28. When the voltage at point A is greater than the first preset voltage threshold, the first transistor N2 is turned on, and the cathode of D12 is now at the first power supply signal voltage VERF. At this time, the voltage at point B is lower than the second power supply signal 12VP after voltage division. The second transistor P4 is a PNP transistor, and the collector voltage is higher than the base voltage. The second transistor P4 is turned on, and the second power supply signal 12VP outputs a spike level with a maximum of the second power supply signal voltage through the third resistor R31. The second end of the third resistor R31 is connected to the protection pin of the control chip. After receiving the high level, the control chip triggers the protection and stops generating and sending the PWM waveform. At this time, regardless of the operating state, the rapid shutdown of the PWM wave effectively protects the circuit safety.

[0071] As can be seen from the above embodiment, the diodes D12 and D14 are provided in this embodiment, which can ensure that the protection action is completed quickly and exits quickly after the protection is completed.

[0072] Figure 2 FIG. 1 shows a flow chart of a control method for a protection device of a switching power supply provided by an embodiment of the present invention. Figure 2 As shown, it is applied to the protection device of the switching power supply as described in the first aspect above, and the process is described in detail as follows:

[0073] S101: Obtaining a maximum on-time limit of a driving signal of the switching power supply,

[0074] The execution subject of this embodiment may be a control chip, which is used to obtain the maximum on-time limit of the driving signal. When the high-level duration of the driving signal in one cycle is greater than the maximum on-time limit, protection is triggered.

[0075] S102: Determine the capacitance of the charging capacitor C29 and the resistance of the resistance unit in the charging circuit 11 according to the maximum on-time limit and the first power signal input to the first switch unit.

[0076] Specifically, to ensure that the first switch can be turned on, a first preset voltage threshold of the output terminal voltage of the charging circuit 11 is set to be greater than the voltage of the first power signal. Exemplarily, the first preset voltage threshold is 0.5V greater than the voltage of the first power signal.

[0077] In one possible implementation, determining the capacitance of the charging capacitor C29 and the resistance of the resistor unit in the charging circuit 11 according to the maximum on-time limit and the first power signal input to the first switch unit includes:

[0078] According to the formula Determine the capacitance of the charging capacitor C29 and the resistance of the resistor unit in the charging circuit 11;

[0079] Among them, t on-max represents the maximum on-time limit, R represents the resistance of the resistor unit, C represents the capacitance of the charging capacitor C29, Vc represents the voltage of the charging capacitor C29, and V represents the voltage of the first power signal.

[0080] In order to achieve adaptive control of the protection device of the switching power supply, this embodiment can select a sliding resistor as the resistance of the resistance unit, and in actual application, determine the resistance of the resistance unit corresponding to different maximum on-time limits based on the above formula, so as to automatically control the resistance change of the sliding resistor through the control chip, thereby ensuring that the protection device of the switching power supply can ensure that the duty cycle of the driving signal does not exceed the limit in any demand scenario, thereby improving the safety and applicability of the circuit, and is particularly suitable for circuits with a large duty cycle and a wide input range, and can play a good protective role.

[0081] An embodiment of the present invention provides a control device for a protection device of a switching power supply. For ease of illustration, only portions related to the embodiment of the present invention are shown. The control device for the protection device of the switching power supply includes:

[0082] A time limit acquisition module, used to obtain a maximum on-time limit of a driving signal of the switching power supply;

[0083] The parameter determination module is used to determine the capacitance of the charging capacitor C29 and the resistance of the resistance unit in the charging circuit 11 according to the maximum on-time limit and the first power signal input to the first switch unit.

[0084] In one possible implementation, the parameter determination module includes:

[0085] According to the formula Determine the capacitance of the charging capacitor C29 and the resistance of the resistor unit in the charging circuit 11;

[0086] Among them, t on-max represents the maximum on-time limit, R represents the resistance of the resistor unit, C represents the capacitance of the charging capacitor C29, Vc represents the voltage of the charging capacitor C29, and V represents the voltage of the first power signal.

[0087] The present application also provides a switching power supply, including the protection circuit of the switching power supply mentioned above.

[0088] Figure 4 Schematic diagram of an electronic device provided by an embodiment of the present invention. Figure 4 As shown, the electronic device 4 of this embodiment includes a processor 40 and a memory 41. The memory 41 stores a computer program 42. When the processor 40 executes the computer program 42, the steps of the above-described method embodiments are implemented. Alternatively, when the processor 40 executes the computer program 42, the functions of the modules / units in the above-described device embodiments are implemented.

[0089] For example, the computer program 42 may be divided into one or more modules / units, which are stored in the memory 41 and executed by the processor 40 to implement the present invention. The one or more modules / units may be a series of computer program instruction segments capable of implementing specific functions, and the instruction segments are used to describe the execution process of the computer program 42 in the electronic device 4.

[0090] The electronic device 4 may include, but is not limited to, a processor 40 and a memory 41. Those skilled in the art will appreciate that Figure 4 It is only an example of the electronic device 4 and does not constitute a limitation on the electronic device 4. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device 4 may also include input and output devices, network access devices, buses, etc.

[0091] The processor 40 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0092] The memory 41 can be an internal storage unit of the electronic device 4, such as a hard disk or memory of the electronic device 4. The memory 41 can also be an external storage device of the electronic device 4, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash memory card, etc. equipped on the electronic device 4. Furthermore, the memory 41 can also include both an internal storage unit of the electronic device 4 and an external storage device. The memory 41 is used to store the computer program 42 and other programs and data required by the electronic device 4. The memory 41 can also be used to temporarily store data that has been output or is about to be output.

[0093] For the sake of convenience and brevity, the division of the above functional modules / units is only used as an example. In actual applications, the above functions can be assigned to different functional modules / units as needed. The above modules / units can be implemented in the form of hardware, software, or a combination of hardware and software.

[0094] An embodiment of the present invention further provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the methods in the above-mentioned method embodiments.

[0095] An embodiment of the present invention further provides a computer program product, including a computer program, which, when executed by a processor, implements the methods in the above-mentioned method embodiments.

[0096] The computer program includes computer program code, which may be in source code form, object code form, executable file, or some intermediate form. Computer-readable media may include any entity or device capable of carrying computer program code, recording media, USB flash drives, mobile hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunications signals, and software distribution media.

[0097] In the above embodiments, the descriptions of each embodiment have their own focus. For parts not described or recorded in detail in one embodiment, please refer to the relevant descriptions of other embodiments. Unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced to each other. The technical features of different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0098] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A protection device for a switching power supply, characterized in that: include: Protection circuit and control module; the protection circuit includes a charging circuit, a voltage clamping circuit and a switching circuit; The first end of the voltage clamping circuit is connected to the signal output end of the control module, the input end of the charging circuit is used to be connected to the input end of the switching power supply, the output end of the charging circuit and the second end of the voltage clamping circuit are both connected to the input end of the switching circuit, and the output end of the switching circuit is connected to the input end of the control module; The charging circuit is used to obtain an input electrical signal of the switching power supply and perform charging based on the input electrical signal; The voltage clamping circuit is used to obtain the driving signal output by the control module to the switching power supply, and clamp the output terminal voltage of the charging circuit to a first voltage when the driving signal is at a low level; The switch circuit is configured to output a protection signal to the control module when the voltage at the output end of the charging circuit is greater than a first preset voltage threshold; The first voltage is less than the first preset voltage threshold; the first preset voltage threshold is the maximum voltage reached by the output terminal voltage of the charging circuit within the first preset time; the first preset time is the maximum on-time limit of the driving signal; The control module stops outputting a driving signal to the switching power supply based on the protection signal.

2. The protection device for a switching power supply according to claim 1, wherein: The charging circuit includes a charging capacitor, a first diode and a resistance unit; The positive electrode of the first diode is the input end of the charging circuit, the negative electrode of the first diode is connected to the first end of the resistance unit, the second end of the resistance unit is connected to the first end of the charging capacitor, the second end of the charging capacitor is grounded, and the first end of the charging capacitor is the output end of the charging circuit.

3. The protection device for a switching power supply according to claim 2, wherein: The resistance unit includes at least one resistor, and each resistor is connected in series between a first end and a second end of the resistance unit.

4. The protection device for a switching power supply according to claim 2, wherein: The resistance unit includes a sliding resistor.

5. The protection device for a switching power supply according to claim 1, wherein: The voltage clamping circuit includes a second diode; The cathode of the second diode is the first end of the voltage clamping circuit, and the anode of the second diode is the second end of the voltage clamping circuit.

6. The protection device for a switching power supply according to claim 1, wherein: The switch circuit includes a first switch tube unit and a second switch tube unit; The first end of the first switch tube unit is the input end of the switch circuit, the second end of the first switch tube unit is connected to the first end of the second switch tube unit, and the third end of the first switch tube unit is used to receive a first power signal; The second end of the second switch tube unit is used to receive a second power supply signal, and the third end of the second switch tube unit is the output end of the switch circuit.

7. The protection device for a switching power supply according to claim 6, wherein: The first switch tube unit includes a first triode and a third diode; The base of the first transistor is the first end of the first switching tube unit, the collector of the first transistor is the second end of the first switching tube unit, and the emitter of the first transistor is the third end of the first switching tube unit; the anode of the third diode is connected to the base of the first transistor, and the cathode of the third diode is connected to the collector of the first transistor.

8. The protection device for a switching power supply according to claim 6, wherein: The second switch tube unit includes a second triode, a first resistor, a second resistor, a third resistor and a fourth diode; The first end of the first resistor is the first end of the second switching tube unit, the second end of the first resistor is respectively connected to the cathode of the fourth diode, the base of the second transistor and the first end of the second resistor, the second end of the second resistor is connected to the collector of the second transistor, and the emitter of the second transistor and the anode of the fourth diode are both connected to the first end of the third resistor; the collector of the second transistor is the second end of the second switching tube unit, and the second end of the third resistor is the third end of the second switching tube unit.

9. A method for controlling a protection device of a switching power supply, characterized in that: A protection device for a switching power supply according to any one of claims 1 to 8, comprising: Obtaining a maximum on-time limit of a driving signal of the switching power supply; The capacitance of the charging capacitor and the resistance of the resistance unit in the charging circuit are determined according to the maximum on-time limit and the first power signal input to the first switch unit.

10. The control method of the protection device of the switching power supply according to claim 9, characterized in that: The determining, based on the maximum on-time limit and the first power signal input to the first switch unit, the capacitance of the charging capacitor and the resistance of the resistance unit in the charging circuit includes: According to the formula Determining the capacitance of the charging capacitor and the resistance of the resistor unit in the charging circuit; Among them, t on-max represents the maximum on-time limit, R represents the resistance of the resistor unit, C represents the capacitance of the charging capacitor, Vc represents the voltage of the charging capacitor, and V represents the voltage of the first power signal.

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