An overvoltage protection circuit for a switching power supply
By combining power control, feedback, delay detection, and self-locking protection modules in the circuit design, the problem of power outage in abnormal conditions under overvoltage protection circuit of switching power supply is solved, thereby improving safety and reliability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHENZHEN CHUXINZHIZHI TECHNOLOGY CO LTD
- Filing Date
- 2025-06-09
- Publication Date
- 2026-05-26
AI Technical Summary
The overvoltage protection circuit of the existing switching power supply cannot properly cut off the power when the feedback circuit fails or the drive device malfunctions, resulting in reduced safety and failure to identify the fault location in a timely manner.
The circuit employs a combination of a power control module, a switching power supply module, a feedback module, a delay detection module, and a self-locking protection module. Overvoltage protection is achieved through voltage sampling, delay detection, and high-level self-locking, ensuring power-off protection and fault display in abnormal situations.
It improves the safety of the switching power supply, enabling timely power-off protection in abnormal situations, and displays the fault type through indicator lights, thereby enhancing the reliability and safety of the system.
Smart Images
Figure CN224289275U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of switching power supply technology, specifically an overvoltage protection circuit for a switching power supply. Background Technology
[0002] A switching power supply, a high-frequency power conversion device, typically uses a feedback circuit composed of an optocoupler and a TL371 to detect overvoltage in its output power. In the event of overvoltage, the power supply stops supplying power, and resumes operation once the overvoltage disappears. However, since only one feedback circuit is used for overvoltage detection, a fault in this circuit or an abnormality in the power supply's drive mechanism will prevent the power supply from performing proper power-off protection control, reducing its safety and making it impossible to promptly pinpoint the fault location. Therefore, improvements are needed. Utility Model Content
[0003] This utility model provides an overvoltage protection circuit for a switching power supply to solve the problems mentioned in the background art.
[0004] To achieve the above objectives, this utility model provides the following technical solution:
[0005] An overvoltage protection circuit for a switching power supply includes: a power control module, a switching power supply module, an output module, a feedback module, a delay detection module, and a self-locking protection module.
[0006] The power control module is connected to the switching power supply module and is used to receive DC power and transmit DC power to the switching power supply module.
[0007] The switching power supply module is connected to the feedback module. It is used to receive the feedback signal output by the feedback module and output a pulse signal, perform high-frequency voltage regulation on DC power and output the first power.
[0008] The output module, connected to the switching power supply module, is used to rectify and filter the first electrical energy and output the second electrical energy.
[0009] The feedback module, connected to the output module, is used to sample the voltage of the second electrical energy and output a sampled signal. It compares the sampled signal with a set voltage threshold and outputs a feedback signal.
[0010] The delay detection module, connected to the feedback module, is used to set the timing period and output a control signal when the duration for which the sampled signal is greater than the feedback signal exceeds the timing period.
[0011] The self-locking protection module is connected to the power control module, switching power supply module, feedback module, and delay detection module. It is used to perform high-level self-locking, display feedback faults, and control the power control module to perform power-off protection when a control signal is received but no feedback signal is received. When a control signal and a pulse signal are received, it performs high-level self-locking, displays switching power supply faults, and controls the power control module to perform power-off protection.
[0012] As a further embodiment of this utility model: the power control module includes a power interface, a first capacitor, a first resistor, a first power transistor, and a first switching transistor;
[0013] Preferably, the first end of the power interface is connected to one end of the first capacitor and the drain of the first power transistor, and is connected to the gate of the first power transistor and the collector of the first switching transistor through the first resistor. The emitter of the first switching transistor is connected to the other end of the first capacitor, the second end of the power interface and the ground terminal. The base of the first switching transistor is connected to the self-locking protection module.
[0014] As a further embodiment of this utility model: the switching power supply module includes a drive controller, a second power transistor, and a first transformer; the output module includes a first diode, a second diode, a second capacitor, and an output port;
[0015] Preferably, the VCC terminal of the drive controller is connected to the first terminal of the primary side of the first comparator and the source of the second power transistor; the OUT terminal of the drive controller is connected to the gate of the second power transistor and the self-locking protection module; the source of the second power transistor is connected to the GND terminal of the drive controller and the second terminal of the power interface; the drain of the first power transistor is connected to the second terminal of the primary side of the first transformer; the first terminal of the secondary side of the first transformer is connected to the anode of the first diode; the second terminal of the secondary side of the first transformer is connected to the anode of the second diode and the second terminal of the output port, and is connected to the first terminal of the output port, the cathode of the second diode, and the cathode of the first diode through the second capacitor.
[0016] As a further improvement of this utility model: the feedback module includes a second resistor, a third resistor, a fourth resistor, a first voltage regulator, and a first optocoupler;
[0017] Preferably, one end of the second resistor is connected to the first end of the output port and is connected to the control terminal of the first voltage regulator and the first end of the fourth resistor through the third resistor. The second end of the fourth resistor is connected to the anode and ground of the first voltage regulator. The cathode of the first voltage regulator is connected to the second end of the first optocoupler. The first end of the first optocoupler is connected to the other end of the second resistor. The third end of the first optocoupler is connected to the FB terminal of the drive controller. The fourth end of the first optocoupler is grounded.
[0018] As a further embodiment of this utility model: the delay detection module includes a first comparator, a first reference power supply, a sixth resistor, a fifth resistor, a second switching transistor, a first power supply, and a third capacitor;
[0019] Preferably, the non-inverting input of the first comparator is connected to the first terminal of the fourth resistor, the inverting input of the first comparator is connected to the first reference power supply, the output terminal of the first comparator is connected to the base of the second switching transistor and one end of the third capacitor through the sixth resistor, the collector of the second switching transistor is connected to the first power supply, and the emitter of the second switching transistor is connected to the self-locking protection module and connected to the other end of the third capacitor and ground through the fifth resistor.
[0020] As a further embodiment of this utility model: the self-locking protection module includes a first logic chip, a fourth diode, a fifth diode, a sixth diode, a seventh diode, an eighth diode, a ninth diode, a tenth diode, an eleventh diode, a second logic chip, a first indicator light, and a second indicator light;
[0021] Preferably, terminal A of the first logic chip is connected to terminal A of the second logic chip, the cathode of the seventh diode, the cathode of the eighth diode, and the emitter of the second switch. Terminal B of the first logic chip is connected to the cathodes of the fifth and fourth diodes. The anode of the fourth diode is connected to the OUT terminal of the drive controller. The anode of the fifth diode is connected to the anode of the first indicator light, the anode of the sixth diode, the anode of the seventh diode, and the Y terminal of the first logic chip. The cathode of the sixth diode is connected to the cathode of the ninth diode and the base of the first switch. The anode of the eighth diode is connected to the anodes of the ninth and tenth diodes, the anode of the second indicator light, and the Y terminal of the second logic chip. The cathode of the tenth diode is connected to the cathode of the eleventh diode and the terminal B of the second logic chip. The anode of the eleventh diode is connected to the FB terminal of the drive controller. The cathodes of the first and second indicator lights are both grounded.
[0022] Compared with the prior art, the beneficial effects of this utility model are as follows: The overvoltage protection circuit of this utility model for switching power supply can have the feedback module sample the voltage of the output module's electrical energy and compare the sampled signal with the voltage magnitude of the set voltage threshold and provide a feedback signal. Then, the switching power supply module performs high-frequency voltage regulation on the DC power transmitted by the power control module according to the feedback signal. The output module then performs rectification, filtering and output. The delay detection module performs secondary overvoltage detection processing on the sampled signal and voltage threshold and provides a high-level signal after a delay. When the self-locking protection module receives the high-level signal output by the delay detection module and the switching power supply or the feedback module is abnormal, it controls the power control module to perform power-off protection, thereby improving the safety of the switching power supply and displaying the switching power supply fault or the feedback fault, respectively. Attached Figure Description
[0023] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0024] Figure 1 This is a schematic block diagram of an overvoltage protection circuit for a switching power supply, provided as an example of this utility model.
[0025] Figure 2 A circuit diagram of an overvoltage protection circuit for a switching power supply provided as an example of this utility model.
[0026] Figure 3 The connection circuit diagram of the self-locking protection module provided for this utility model embodiment. Detailed Implementation
[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0028] In one embodiment, see Figure 1 An overvoltage protection circuit for a switching power supply includes: a power control module 1, a switching power supply module 2, an output module 3, a feedback module 4, a delay detection module 5, and a self-locking protection module 6.
[0029] Specifically, the power control module 1 is connected to the switching power supply module 2 and is used to receive DC power and transmit DC power to the switching power supply module 2.
[0030] The switching power supply module 2 is connected to the feedback module 4 and is used to receive the feedback signal output by the feedback module 4 and output a pulse signal to perform high-frequency voltage regulation on the DC power and output the first power.
[0031] Output module 3, connected to switching power supply module 2, is used to rectify and filter the first electrical energy and output the second electrical energy;
[0032] Feedback module 4, connected to output module 3, is used to sample the voltage of the second electrical energy and output a sampling signal, compare the sampling signal with a set voltage threshold, and output a feedback signal.
[0033] The delay detection module 5 is connected to the feedback module 4 and is used to set the timing time. When the duration of the sampling signal being greater than the feedback signal exceeds the timing time, the control signal is output.
[0034] The self-locking protection module 6 is connected to the power control module 1, the switching power supply module 2, the feedback module 4, and the delay detection module 5. It is used to perform high-level self-locking, display feedback faults, and control the power control module 1 to perform power-off protection when a control signal is received but no feedback signal is received. When a control signal and a pulse signal are received, it performs high-level self-locking, displays switching power supply faults, and controls the power control module 1 to perform power-off protection.
[0035] In a specific embodiment, the power control module 1 can be a power control circuit composed of a power interface, a field-effect transistor, a transistor, etc., which can receive DC power and control the transmission state of DC power; the switching power supply module 2 can be a switching power supply circuit composed of a pulse driver, a field-effect transistor, and a transformer, which can perform high-frequency voltage regulation; the output module 3 can be an output circuit composed of diodes, capacitors, and output ports, which can rectify and filter the input power; the feedback module 4 can be a feedback circuit composed of resistors, optocouplers, and adjustable voltage regulators, which can sample the voltage of the power input to the output module 3, compare the sampled signal with the set voltage threshold, and provide a feedback signal; the delay detection module 5 can be a delay detection circuit composed of comparators, resistors, transistors, etc., which can perform secondary overvoltage detection and provide a high-level signal after a delay after an overvoltage occurs; the self-locking protection module 6 can be a self-locking protection circuit composed of logic chips, diodes, and indicator lights, which can perform high-level self-locking processing on the input signal and control the power control module 1 to perform power-off protection, and display feedback faults or switching power supply faults.
[0036] In another embodiment, please refer to Figure 1 , Figure 2 and Figure 3 The power control module 1 includes a power interface, a first capacitor C1, a first resistor R1, a first power transistor Q1, and a first switching transistor V1.
[0037] Specifically, the first end of the power interface is connected to one end of the first capacitor C1 and the drain of the first power transistor Q1, and is connected to the gate of the first power transistor Q1 and the collector of the first switching transistor V1 through the first resistor R1. The emitter of the first switching transistor V1 is connected to the other end of the first capacitor C1, the second end of the power interface and the ground. The base of the first switching transistor V1 is connected to the self-locking protection module 6.
[0038] In a specific embodiment, the first power transistor Q1 can be an N-channel MOSFET; the first switching transistor V1 can be an NPN transistor.
[0039] Furthermore, the switching power supply module 2 includes a drive controller IC1, a second power transistor Q2, and a first transformer B1; the output module 3 includes a first diode D1, a second diode D2, a second capacitor C2, and an output port;
[0040] Specifically, the VCC terminal of the drive controller IC1 is connected to the first terminal of the primary side of the first comparator A1 and the source of the second power transistor Q2. The OUT terminal of the drive controller IC1 is connected to the gate of the second power transistor Q2 and the self-locking protection module 6. The source of the second power transistor Q2 is connected to the GND terminal of the drive controller IC1 and the second terminal of the power interface. The drain of the first power transistor Q1 is connected to the second terminal of the primary side of the first transformer B1. The first terminal of the secondary side of the first transformer B1 is connected to the anode of the first diode D1. The second terminal of the secondary side of the first transformer B1 is connected to the anode of the second diode D2 and the second terminal of the output port, and is connected to the first terminal of the output port, the cathode of the second diode D2 and the cathode of the first diode D1 through the second capacitor C2.
[0041] In a specific embodiment, the drive controller IC1 can be a UC3842 controller; the second power transistor Q2 can be an N-channel MOSFET.
[0042] Furthermore, the feedback module 4 includes a second resistor R2, a third resistor R3, a fourth resistor R4, a first voltage regulator IC3, and a first optocoupler IC2;
[0043] Specifically, one end of the second resistor R2 is connected to the first end of the output port and is connected to the control terminal of the first voltage regulator IC3 and the first end of the fourth resistor R4 through the third resistor R3. The second end of the fourth resistor R4 is connected to the anode and ground of the first voltage regulator IC3. The cathode of the first voltage regulator IC3 is connected to the second end of the first optocoupler IC2. The first end of the first optocoupler IC2 is connected to the other end of the second resistor R2. The third end of the first optocoupler IC2 is connected to the FB terminal of the drive controller IC1. The fourth end of the first optocoupler IC2 is grounded.
[0044] In a specific embodiment, the first optocoupler IC2 can be a PC817 optocoupler; the first voltage regulator IC3 can be a TL431 voltage regulator.
[0045] Furthermore, the delay detection module 5 includes a first comparator A1, a first reference power supply VREF, a sixth resistor R6, a fifth resistor R5, a second switch V2, a first power supply VCC1, and a third capacitor C3.
[0046] Specifically, the non-inverting input of the first comparator A1 is connected to the first terminal of the fourth resistor R4, the inverting input of the first comparator A1 is connected to the first reference power supply VREF, the output terminal of the first comparator A1 is connected to the base of the second switching transistor V2 and one terminal of the third capacitor C3 through the sixth resistor R6, the collector of the second switching transistor V2 is connected to the first power supply VCC1, and the emitter of the second switching transistor V2 is connected to the self-locking protection module 6 and connected to the other terminal of the third capacitor C3 and ground through the fifth resistor R5.
[0047] In a specific embodiment, the first comparator A1 can be an LM358 comparator; the first reference power supply VREF can be set with a voltage threshold, which is the required output voltage and is equal to the voltage threshold set by the first voltage regulator IC3; the second switch V2 can be an NPN transistor; and the sixth resistor R6 and the third capacitor C3 are set with a timing period.
[0048] Furthermore, the self-locking protection module 6 includes a first logic chip J1, a fourth diode D4, a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8, a ninth diode D9, a tenth diode D10, an eleventh diode D11, a second logic chip J2, a first indicator LED1, and a second indicator LED2.
[0049] Specifically, terminal A of the first logic chip J1 is connected to terminal A of the second logic chip J2, the cathode of the seventh diode D7, the cathode of the eighth diode D8, and the emitter of the second switch V2. Terminal B of the first logic chip J1 is connected to the cathode of the fifth diode D5 and the cathode of the fourth diode D4. The anode of the fourth diode D4 is connected to the OUT terminal of the drive controller IC1. The anode of the fifth diode D5 is connected to the anode of the first indicator LED1, the anode of the sixth diode D6, the anode of the seventh diode D7, and the Y terminal of the first logic chip J1. The cathode of the sixth diode D6 is connected to the cathode of the ninth diode D9 and the base of the first switch V1. The anode of the eighth diode D8 is connected to the anode of the ninth diode D9, the anode of the tenth diode D10, the anode of the second indicator LED2, and the Y terminal of the second logic chip J2. The cathode of the tenth diode D10 is connected to the cathode of the eleventh diode D11 and the B terminal of the second logic chip J2. The anode of the eleventh diode D11 is connected to the FB terminal of the drive controller IC1. The cathodes of the first indicator LED1 and the second indicator LED2 are both grounded.
[0050] In a specific embodiment, both the first logic chip J1 and the second logic chip J2 can be AND gate chips. The first logic chip J1 works with the fourth diode D4, the fifth diode D5 and the seventh diode D7 to perform high-level self-locking, and the second logic chip J2 works with the eleventh diode D11, the tenth diode D10 and the eighth diode D8 to perform high-level self-locking.
[0051] In this embodiment of an overvoltage protection circuit for a switching power supply, DC power is input through a power interface. A first power transistor Q1 transmits the DC power to a drive controller IC1. The drive controller IC1 drives the second power transistor Q2 to conduct, cooperating with a first transformer B1 to perform high-frequency voltage regulation and output the first power. The first power is rectified and filtered by a first diode D1, a second diode D2, and a second capacitor C2 before being output from the output port. A first voltage regulator IC3 sets a voltage threshold, and a third resistor R3 and a fourth resistor R4 sample the output voltage. The sampled signal is compared with the voltage threshold, and the conduction state of the first optocoupler IC2 is controlled. This provides a feedback signal to the FB terminal of the drive controller IC1, enabling the drive controller IC1 to further adjust the conduction state of the second power transistor Q2 to achieve regulated output. When the feedback module 4 detects an overvoltage, under normal circumstances, the drive controller IC1 will stop working. However, during an overvoltage event, the power supply is not stopped. At this time, the first comparator A1 will output a high voltage. Upon completion of the secondary overvoltage detection, the third capacitor C3 will store energy and set a timer. When the stored energy in the third capacitor C3 reaches the conduction voltage of the second switch V2, it indicates that the duration of the secondary overvoltage exceeds the timer, triggering the second switch V2 to conduct. The A terminals of the first logic chip J1 and the second logic chip J2 will become high. If the first optocoupler IC2 fails to conduct normally at this time, the FB terminal of the drive controller IC1 will be high, causing the second logic chip J2 to self-lock in conjunction with the eleventh diode D11, the tenth diode D10, and the eighth diode D8. The second indicator LED2 will display the feedback abnormality and control the first switch V1 to conduct, while the first power transistor Q1 will be cut off. When the OUT terminal of the drive controller IC1 maintains a pulse signal output, the first logic chip J1 will self-lock at a high level in conjunction with the fourth diode D4, the fifth diode D5, and the seventh diode D7. The first indicator LED1 will display the switching power supply abnormality and control the first power transistor Q1 to be cut off.
[0052] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
[0053] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. An overvoltage protection circuit for a switching power supply, characterized in that, The overvoltage protection circuit of the switching power supply includes: a power control module, a switching power supply module, an output module, a feedback module, a delay detection module, and a self-locking protection module; The power control module is connected to the switching power supply module and is used to receive DC power and transmit DC power to the switching power supply module. The switching power supply module is connected to the feedback module. It is used to receive the feedback signal output by the feedback module and output a pulse signal, perform high-frequency voltage regulation on DC power and output the first power. The output module, connected to the switching power supply module, is used to rectify and filter the first electrical energy and output the second electrical energy. The feedback module, connected to the output module, is used to sample the voltage of the second electrical energy and output a sampled signal. It compares the sampled signal with a set voltage threshold and outputs a feedback signal. The delay detection module, connected to the feedback module, is used to set the timing period and output a control signal when the duration for which the sampled signal is greater than the feedback signal exceeds the timing period. The self-locking protection module is connected to the power control module, the switching power supply module, the feedback module, and the delay detection module. It is used to perform high-level self-locking, display feedback faults, and control the power control module to perform power-off protection when a control signal is received but no feedback signal is received. When a control signal is received and a pulse signal is received, it performs high-level self-locking, displays switching power supply faults, and controls the power control module to perform power-off protection. The self-locking protection module includes a first logic chip, a fourth diode, a fifth diode, a sixth diode, a seventh diode, an eighth diode, a ninth diode, a tenth diode, an eleventh diode, a second logic chip, a first indicator light, and a second indicator light; The A terminal of the first logic chip is connected to the A terminal of the second logic chip, the cathode of the seventh diode, the cathode of the eighth diode, and the emitter of the second switch. The B terminal of the first logic chip is connected to the cathodes of the fifth and fourth diodes. The anode of the fourth diode is connected to the OUT terminal of the drive controller. The anode of the fifth diode is connected to the anodes of the first indicator light, the sixth diode, the seventh diode, and the Y terminal of the first logic chip. The cathode of the sixth diode is connected to the cathode of the ninth diode and the base of the first switch. The anode of the eighth diode is connected to the anodes of the ninth and tenth diodes, the anode of the second indicator light, and the Y terminal of the second logic chip. The cathode of the tenth diode is connected to the cathode of the eleventh diode and the B terminal of the second logic chip. The anode of the eleventh diode is connected to the FB terminal of the drive controller. The cathodes of the first and second indicator lights are both grounded.
2. The overvoltage protection circuit for a switching power supply according to claim 1, characterized in that, The power control module includes a power interface, a first capacitor, a first resistor, a first power transistor, and a first switching transistor. The first end of the power interface is connected to one end of the first capacitor and the drain of the first power transistor, and is connected to the gate of the first power transistor and the collector of the first switching transistor through the first resistor. The emitter of the first switching transistor is connected to the other end of the first capacitor, the second end of the power interface and the ground terminal. The base of the first switching transistor is connected to the self-locking protection module.
3. The overvoltage protection circuit for a switching power supply according to claim 2, characterized in that, The switching power supply module includes a drive controller, a second power transistor, and a first transformer; the output module includes a first diode, a second diode, a second capacitor, and an output port. The VCC terminal of the drive controller is connected to the first terminal of the primary side of the first comparator and the source of the second power transistor. The OUT terminal of the drive controller is connected to the gate of the second power transistor and the self-locking protection module. The source of the second power transistor is connected to the GND terminal of the drive controller and the second terminal of the power interface. The drain of the first power transistor is connected to the second terminal of the primary side of the first transformer. The first terminal of the secondary side of the first transformer is connected to the anode of the first diode. The second terminal of the secondary side of the first transformer is connected to the anode of the second diode and the second terminal of the output port, and is connected to the first terminal of the output port, the cathode of the second diode, and the cathode of the first diode through the second capacitor.
4. The overvoltage protection circuit for a switching power supply according to claim 3, characterized in that, The feedback module includes a second resistor, a third resistor, a fourth resistor, a first voltage regulator, and a first optocoupler; One end of the second resistor is connected to the first end of the output port and is connected to the control terminal of the first voltage regulator and the first end of the fourth resistor through the third resistor. The second end of the fourth resistor is connected to the anode and ground of the first voltage regulator. The cathode of the first voltage regulator is connected to the second end of the first optocoupler. The first end of the first optocoupler is connected to the other end of the second resistor. The third end of the first optocoupler is connected to the FB terminal of the drive controller. The fourth end of the first optocoupler is grounded.
5. The overvoltage protection circuit for a switching power supply according to claim 4, characterized in that, The delay detection module includes a first comparator, a first reference power supply, a sixth resistor, a fifth resistor, a second switching transistor, a first power supply, and a third capacitor; The non-inverting input of the first comparator is connected to the first terminal of the fourth resistor, the inverting input of the first comparator is connected to the first reference power supply, the output terminal of the first comparator is connected to the base of the second switching transistor and one end of the third capacitor through the sixth resistor, the collector of the second switching transistor is connected to the first power supply, and the emitter of the second switching transistor is connected to the self-locking protection module and connected to the other end of the third capacitor and ground through the fifth resistor.