Overvoltage protection circuit and electronic device

Abstract

The application discloses an overvoltage protection circuit and an electronic device. The overvoltage protection circuit comprises a first switch circuit, a voltage conversion circuit, a second switch circuit and a controller. The first switch circuit is electrically connected with the voltage, the voltage conversion circuit, the controller and the second switch circuit. The voltage conversion circuit and the second switch circuit are electrically connected to an output end. The overvoltage protection circuit is configured to: in response to a control signal output by the controller being a first level and the second switch circuit being turned off, the first switch circuit is turned on, the voltage conversion circuit converts an input voltage into an output voltage, in response to the output voltage being greater than a first voltage threshold, the second switch circuit is turned on, so that the first switch circuit is turned off, the output voltage is reduced, until the output voltage is reduced to less than or equal to the first voltage threshold, the second switch circuit is turned off, the first switch circuit is turned on, and the output voltage is increased. In the above manner, overvoltage protection can be effectively realized, and power supply can be maintained when an overvoltage fault occurs.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and in particular to an overvoltage protection circuit and electronic device. Background Technology

[0002] In electronic devices, especially in critical applications involving personal and equipment safety such as battery management systems (BMS), functional safety design is a core requirement to ensure that the system can maintain a safe operating state even in the event of a single point of failure.

[0003] In BMS products, BUCK-type switching power supplies are typically used to provide stable operating voltages for downstream circuits such as control logic, communication modules, and sensors. However, BUCK power chips themselves have a failure risk. For example, a short circuit in the internal power switch can cause high input voltage (i.e., battery bus voltage) to be directly conducted to the output. Without effective protection measures, this overvoltage will be transmitted to voltage-sensitive downstream low-voltage circuits (such as MCUs), causing device breakdown, malfunction, or even thermal runaway, rendering the BMS unable to monitor safety and potentially leading to serious safety incidents. Summary of the Invention

[0004] This application provides an overvoltage protection circuit and electronic device that can effectively achieve overvoltage protection and maintain power supply when an overvoltage fault occurs.

[0005] In a first aspect, embodiments of this application provide an overvoltage protection circuit, including: a first switching circuit, a voltage conversion circuit, a second switching circuit, and a controller; the first switching circuit is electrically connected between the input voltage and the voltage conversion circuit, and the first switching circuit is also electrically connected to the controller and the second switching circuit; the voltage conversion circuit and the second switching circuit are electrically connected at the output terminal, and the voltage at the output terminal is the output voltage; the overvoltage protection circuit is configured to: in response to a control signal output by the controller being at a first level and the second switching circuit being off, the first switching circuit is turned on, and the voltage conversion circuit converts the input voltage into the output voltage; in response to the output voltage being greater than a first voltage threshold, the second switching circuit is turned on, causing the first switching circuit to turn off, and the output voltage decreases, until the output voltage decreases to less than or equal to the first voltage threshold, the second switching circuit turns off, the first switching circuit is turned on, and the output voltage increases.

[0006] In one or more embodiments, the first switching circuit includes a first switch and a second switch; a first terminal of the first switch is electrically connected to a third terminal of the second switch, a second terminal of the first switch is electrically connected to an input voltage, a third terminal of the first switch is electrically connected to a voltage conversion circuit, a first terminal of the second switch is electrically connected to a controller and the second switching circuit, and a second terminal of the second switch is grounded.

[0007] In one or more embodiments, the first switching circuit further includes a first resistor, a second resistor, a third resistor, and a fourth resistor; the first resistor is electrically connected between the third terminal of the first switch and the voltage conversion circuit, the second resistor is electrically connected between the first terminal and the second terminal of the first switch, the third resistor is electrically connected between the first terminal of the first switch and the third terminal of the second switch, and the fourth resistor is electrically connected between the first terminal of the second switch and the controller; wherein, the first switch is a PMOS transistor and the second switch is an NPN transistor.

[0008] In one or more embodiments, the voltage conversion circuit includes a first capacitor, a second capacitor, a first inductor, and a BUCK chip; the first capacitor is electrically connected between the power supply terminal of the BUCK chip and ground, the first inductor and the second capacitor are connected in series between the switching terminal of the BUCK chip and ground, and the connection node between the first inductor and the second capacitor is electrically connected to the output terminal.

[0009] In one or more embodiments, the minimum value of the second capacitor is: Among them, C out I is the minimum value of the second capacitor. out The output current is T, r is the inductor current ripple factor, and T is the output current at the output terminal. on For the conduction period, T off For the shutdown period, V outripp This is the output ripple voltage.

[0010] In one or more embodiments, the minimum value of the first capacitor is: Among them, C in I is the minimum value of the first capacitor. inmax V represents the maximum input current. inmin denoted as the minimum input voltage, and 'a' as the preset voltage coefficient.

[0011] In one or more embodiments, the second switching circuit includes a Zener diode, a fifth resistor, a sixth resistor, a seventh resistor, and a third switch; the cathode of the Zener diode is electrically connected to the output terminal, the anode of the Zener diode is electrically connected to the first terminal of the fifth resistor, the second terminal of the fifth resistor is electrically connected to the first terminals of the sixth and seventh resistors, the second terminal of the sixth resistor and the second terminal of the third switch are both grounded, the second terminal of the seventh resistor is electrically connected to the first terminal of the third switch, and the third terminal of the third switch is electrically connected to the first switching circuit; wherein, the third switch is an NPN transistor.

[0012] In one or more embodiments, the second switching circuit further includes an eighth resistor and a third capacitor; the eighth resistor and the third capacitor are connected in series between the third terminal of the third switch and the second terminal of the fifth resistor.

[0013] In one or more embodiments, the overvoltage protection circuit further includes a voltage divider circuit electrically connected to the output terminal and the controller respectively; the overvoltage protection circuit is configured such that: the voltage divider circuit divides the output voltage and outputs a detection voltage to the controller; in response to the detection voltage being greater than a second voltage threshold, the controller outputs a control signal at a second level to control the first switching circuit to turn off, wherein when the output voltage is greater than a third voltage threshold, the detection voltage is greater than the second voltage threshold, and the third voltage threshold is greater than the first voltage threshold.

[0014] Secondly, embodiments of this application provide an electronic device including the overvoltage protection circuit as described in the first aspect.

[0015] The beneficial effects of this application are as follows: The overvoltage protection circuit of this application embodiment includes a first switching circuit, a voltage conversion circuit, a second switching circuit, and a controller. The first switching circuit is electrically connected between the input voltage and the voltage conversion circuit, and is also electrically connected to the controller and the second switching circuit. The voltage conversion circuit and the second switching circuit are electrically connected to the output terminal, and the voltage at the output terminal is the output voltage. When no overvoltage fault occurs, the output voltage is less than or equal to a first voltage threshold, the second switching circuit is turned off, the control signal output by the controller is at a first level, the first switching circuit is turned on, and the voltage conversion circuit converts the input voltage into the output voltage. When an overvoltage fault occurs, the output voltage is greater than the first voltage threshold, the second switching circuit is turned on, causing the first switching circuit to turn off, thereby effectively realizing overvoltage protection and helping to reduce the risk of device damage. After the first switching circuit is turned off, the output voltage gradually decreases until it decreases again to less than or equal to the first voltage threshold. Then, the second switching circuit is turned off, the first switching circuit is turned on, and the voltage conversion circuit converts the input voltage into the output voltage, increasing the output voltage. In this way, the output voltage will always fluctuate periodically around the first voltage threshold, thus maintaining power supply to downstream circuits or equipment in the event of an overvoltage fault. Attached Figure Description

[0016] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, which are not intended to limit the embodiments, and elements having the same reference numerals in the drawings are designated as similar elements.

[0017] Figure 1 This is a schematic diagram of the overvoltage protection circuit provided in the embodiments of this application. Figure 1 ; Figure 2 This is a schematic diagram of the overvoltage protection circuit provided in the embodiments of this application. Figure 2 ; Figure 3 This is a schematic diagram of the overvoltage protection circuit provided in the embodiments of this application. Figure 3 ; Figure 4This is a schematic diagram of the overvoltage protection circuit provided in the embodiments of this application. Figure 4 ; Figure 5 This is a schematic diagram of the overvoltage protection circuit provided in the embodiments of this application. Figure 5 . Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be described clearly and in detail below with reference to the accompanying drawings. Obviously, the embodiments in this application are only some embodiments, not all embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0019] It should be noted that when an element is described as "connected" to another element, it can be directly connected to the other element, or there can be one or more intermediate elements between them.

[0020] Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0021] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the block diagram of the overvoltage protection circuit provided in the embodiments of this application. Figure 1 As shown, the overvoltage protection circuit 100 includes a first switching circuit 110, a voltage conversion circuit 120, a second switching circuit 130, and a controller 140.

[0022] The first switching circuit 110 is electrically connected between the input voltage VI and the voltage conversion circuit 120. The first switching circuit 110 is also electrically connected to the controller 140 and the second switching circuit 130. The voltage conversion circuit 120 and the second switching circuit 130 are electrically connected to the output terminal, and the voltage at the output terminal is the output voltage VO.

[0023] The overvoltage protection circuit 100 is configured such that: in response to the control signal output by the controller 140 being at a first level and the second switching circuit 130 being turned off, the first switching circuit 110 is turned on, and the voltage conversion circuit 120 converts the input voltage VI into the output voltage VO; in response to the output voltage VI being greater than a first voltage threshold, the second switching circuit 130 is turned on, causing the first switching circuit 110 to be turned off, and the output voltage VO decreases until the output voltage VO decreases to less than or equal to the first voltage threshold, at which point the second switching circuit 130 is turned off, the first switching circuit 110 is turned on, and the output voltage VO increases.

[0024] The first voltage threshold is a preset voltage reference value, which characterizes the upper limit of the system's normal operating range. When the output voltage is less than or equal to this value, the system determines that no overvoltage fault has occurred, thereby maintaining normal voltage conversion and power supply functions. The first level is either high or low, and the second level is either high or low. When the first level is high, the second level is low; when the first level is low, the second level is high.

[0025] Thus, when no overvoltage fault occurs, the output voltage VO is less than or equal to the first voltage threshold, the second switching circuit 130 is turned off, the control signal output by the controller 140 is at the first level, the first switching circuit 110 is turned on, and the voltage conversion circuit 120 converts the input voltage VI into the output voltage VO.

[0026] When an overvoltage fault occurs, the output voltage VO is greater than the first voltage threshold, and the second switching circuit 130 is turned on to turn off the first switching circuit 110, thereby effectively realizing overvoltage protection and helping to reduce the risk of device damage.

[0027] After the first switching circuit 110 is turned off, since the output voltage VO supplies power to the downstream circuits or devices electrically connected to the output terminal, and the voltage conversion circuit 120 loses its power supply from the input voltage VI due to the disconnection of the first switching circuit 110, the output voltage VO gradually decreases until it decreases again to less than or equal to the first voltage threshold. At this point, the second switching circuit 130 is turned off, the control signal output by the controller 140 remains at the first level, the first switching circuit 110 is turned on, and the voltage conversion circuit 120 continues to convert the input voltage VI into the output voltage VO, causing the output voltage VO to increase. In this way, the output voltage VO will always fluctuate periodically around the first voltage threshold, achieving automatic overvoltage protection and recovery without manual intervention.

[0028] In summary, when an overvoltage fault occurs, it can effectively provide overvoltage protection while simultaneously maintaining power supply to downstream circuits or equipment.

[0029] In some embodiments, such as Figure 2 As shown, the first switching circuit 110 includes a first switch Q1 and a second switch Q2.

[0030] Wherein, the first terminal of the first switch Q1 is electrically connected to the third terminal of the second switch Q2, the second terminal of the first switch Q1 is electrically connected to the input voltage VI, the third terminal of the first switch Q1 is electrically connected to the voltage conversion circuit 120, the first terminal of the second switch Q2 is electrically connected to the controller 140 and the second switch circuit 130, and the second terminal of the second switch Q2 is grounded to GND.

[0031] Specifically, when the second switch circuit 130 is turned on and / or the control signal output by the controller 140 is at the second level, the second switch Q2 is turned off, and the first switch Q1 is also turned off to disconnect the electrical connection between the input power supply VI and the voltage conversion circuit 120, thereby realizing overvoltage protection.

[0032] When the second switch circuit 130 is turned off and the control signal output by the controller 140 is at the first level, the second switch Q2 is turned on, and the first switch Q1 is also turned on to establish an electrical connection between the input power supply VI and the voltage conversion circuit 120. The voltage conversion circuit 120 converts the input voltage VI into the output voltage VO.

[0033] Please refer to Figure 3 , Figure 3 This application provides a circuit structure as an embodiment. For example... Figure 3 As shown, the first switching circuit 110 also includes a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4.

[0034] The first resistor R1 is electrically connected between the third terminal of the first switch Q1 and the voltage conversion circuit 120; the second resistor R2 is electrically connected between the first and second terminals of the first switch Q1; the third resistor R3 is electrically connected between the first terminal of the first switch Q1 and the third terminal of the second switch Q2; and the fourth resistor R4 is electrically connected between the first terminal of the second switch Q2 and the controller 140.

[0035] Specifically, the first resistor R1 is a current-limiting resistor. The second resistor R2 and the third resistor R3 are used for voltage division to provide the turn-on voltage for the first switch Q1.

[0036] This embodiment uses a PMOS transistor as the first switch Q1 and an NPN transistor as the second switch Q2. The first terminal of the first switch Q1 is the gate of the PMOS transistor, the second terminal is the source of the PMOS transistor, and the third terminal is the drain of the PMOS transistor. The first terminal of the second switch Q2 is the base of the NPN transistor, the second terminal is the emitter of the NPN transistor, and the third terminal is the collector of the NPN transistor.

[0037] In some embodiments, please continue to refer to Figure 3 The voltage conversion circuit 120 includes a first capacitor C1, a second capacitor C2, a first inductor L1, and a BUCK chip U1.

[0038] The first capacitor C1 is electrically connected between the power supply terminal VIN of the BUCK chip U1 and ground GND. The first inductor L1 and the second capacitor C2 are connected in series between the switch terminal SW of the BUCK chip U1 and ground GND. The connection node between the first inductor L1 and the second capacitor C2 is electrically connected to the output terminal VO.

[0039] The first capacitor C1, the second capacitor C2, the first inductor L1, and the BUCK chip U1 form the BUCK circuit. The first capacitor C1 is used for filtering to suppress input voltage ripple; the second capacitor C2 is used for filtering to stabilize the output voltage; and the first inductor L1 is used for energy storage and energy transfer, and to smooth the current.

[0040] The BUCK chip (also known as a buck DC-DC converter chip) U1 is a power management integrated circuit specifically designed to implement a BUCK (buck) topology. The BUCK chip U1 provides functions such as control logic, MOSFET drive, and feedback regulation.

[0041] In some embodiments, please continue to refer to Figure 3 The second switching circuit 130 includes a Zener diode D1, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, and a third switch Q3.

[0042] In this circuit, the cathode of Zener diode D1 is electrically connected to the output terminal, the anode of Zener diode D1 is electrically connected to the first terminal of the fifth resistor R5, the second terminal of the fifth resistor R5 is electrically connected to the first terminal of the sixth resistor R6 and the first terminal of the seventh resistor R7, the second terminal of the sixth resistor R6 and the second terminal of the third switch Q3 are both grounded to GND, the second terminal of the seventh resistor R7 is electrically connected to the first terminal of the third switch Q3, and the third terminal of the third switch Q3 is electrically connected to the first switch circuit 110.

[0043] In this embodiment, the third switch Q3 is an NPN transistor. The first terminal of the third switch Q3 is the base of the NPN transistor, the second terminal of the third switch Q3 is the emitter of the NPN transistor, and the third terminal of the third switch Q3 is the collector of the NPN transistor.

[0044] In some embodiments, please continue to refer to Figure 3 The second switching circuit 130 also includes an eighth resistor R8 and a third capacitor C3.

[0045] Among them, the eighth resistor R8 and the third capacitor C3 are connected in series between the third terminal of the third switch Q3 and the second terminal of the fifth resistor R5.

[0046] Specifically, during normal operation, the control signal output by the controller 140 is at a first level (high level in this embodiment). This high level is input to the second switch Q2 to turn it on. Consequently, the input voltage VI is divided across the second resistor R2 and the third resistor R3, driving the first switch Q1 to turn it on. After the input voltage VI passes through the BUCK circuit composed of the BUCK chip U1 and the inductor L1, it is stepped down to obtain the output voltage VO.

[0047] When the BUCK chip U1 is short-circuited, it can be assumed that the power supply terminal VIN of the BUCK chip U1 is directly connected to the switching terminal SW, and the output voltage VO rises rapidly due to the influence of the input voltage VI. Once the output voltage VO exceeds the set protection voltage (i.e., the first voltage threshold), the third switch Q3 turns on, pulling the base of the second switch Q2 low. The second switch Q2 then turns off, and the first switch Q1 also turns off. This effectively achieves overvoltage protection, which helps reduce the risk of device damage.

[0048] Subsequently, since the output voltage VO at the output terminal supplies power to the downstream circuits or devices electrically connected to the output terminal, the output voltage VO will decrease. Until the output voltage VO decreases again to less than or equal to the first voltage threshold, the third switch Q3 turns off again, and both the second switch Q2 and the first switch Q1 turn on again to maintain the output voltage VO. In this way, the output voltage VO will always fluctuate periodically around the first voltage threshold, achieving automatic overvoltage protection and recovery without manual intervention. Therefore, it can effectively achieve overvoltage protection and also maintain power supply to downstream circuits or devices in the event of an overvoltage fault.

[0049] for Figure 3 In addition to the circuit structure shown, this application further sets the parameters of some of the components to improve the reliability and stability of the overvoltage protection circuit 100.

[0050] (1) The capacitance of the second capacitor C2 is less than or equal to the capacitance of the first capacitor C1. Since the BUCK circuit composed of the BUCK chip U1, inductor L1, first capacitor C1 and second capacitor C2 has nonlinear devices such as inductance and capacitance, if the BUCK chip is short-circuited and considered as a closed circuit, the first switch Q1, the first inductor L1 and the second capacitor C2 form a new BUCK circuit so that the output voltage VO does not exceed the set value. After the BUCK chip breaks down, the charge of the input capacitor (i.e., the first capacitor C1) is transferred to the output capacitor (i.e., the second capacitor C2), which is used as the basis for capacitor selection.

[0051] Specifically, the formula for capacitor voltage and current is I = CV / T. The current IL of the first inductor L1 is a triangular wave, and its average value is equal to the output current Iout; the peak value of the ripple current is... IL. Therefore, the peak value of the part of the current IL of the first inductor L1 that exceeds the output current Iout is IL / 2. The current that exceeds the output current Iout is absorbed by the second capacitor C2. The waveform of the current IC of the second capacitor C2 is a triangular wave, and the peak value is IL / 2, and the average charging current is half of the peak value, that is IL / 4. The second capacitor C2 is charged within half a switching period (T = Ton + Toff is the switching period). The charging charge Q of the second capacitor C2 is: Q = IL / 4 (T / 2) = ( IL T) / 8. From Q = C2 VC / we get: VC = Q / C = ( IL T) / (8 C2), where VC is the change in the voltage across the second capacitor C2. According to the ripple voltage requirement, it is necessary to make VC ≤ Voutripp, so the capacitance of the second capacitor C2 needs to satisfy C2 ≥ ( IL T) / (8 Voutripp), where IL = Iout r, T = Ton + Toff. Thus, finally, the minimum value of the second capacitor C2 can be obtained as: ; where C out is the minimum value of the second capacitor, I out is the output current at the output terminal, r is the inductor current ripple coefficient, T on is the conduction period, T off is the off period, V outripp is the output ripple voltage. The inductor current ripple coefficient is a preset parameter, which can be preset based on parameters such as inductor size, loss, and the working mode of the BUCK circuit; the output ripple voltage is a preset voltage. In some embodiments, for the BUCK circuit, the output ripple voltage can be set not to exceed 1% of the output voltage.

[0052] (2) In practical use, due to the internal resistance and line inductance of the circuit, the input capacitor (i.e., the first capacitor C1) will provide a small current to the circuit. Therefore, considering the input capacitance value required to maintain a constant input voltage VI when the input voltage VI changes instantaneously, the minimum value of the first capacitor C1 can be obtained according to the capacitance formula I=CV / T. Thus, the minimum value of the first capacitor C1 is: ; Among them, C in I is the minimum value of the first capacitor C1. inmax V represents the maximum input current. inmin is the minimum input voltage, and 'a' is the preset voltage coefficient. inmax and V inmin All values ​​are preset. When a short circuit occurs, the first capacitor C1 needs to maintain the input voltage VI at no less than 90% for a period of time to ensure that the subsequent circuit will not suddenly lose power and to complete the alarm and protection. The preset voltage coefficient a is set accordingly.

[0053] (3) The first voltage threshold can be determined based on the Zener diode D1, the fifth resistor R5 and the sixth resistor R6. Then the first voltage threshold Vset is: Vset=VD1+VR5+VR6=VD1+VBE (R5+R6) / R6, where VBE is the voltage between the base and emitter of the third switch Q3 when the third switch Q3 is turned on.

[0054] (4) The eighth resistor R8 and the third capacitor C3 are hysteresis compensation components. By properly configuring the parameters, the feedback delay can be adjusted, thereby adjusting the switching state of the first switch Q1, so that the first switch Q1 switches at the set frequency without entering the linear state. Increasing the capacitance of the third capacitor C3 and decreasing the resistance of the eighth resistor R8 can reduce the switching frequency; conversely, it can increase the switching frequency. The basis for setting the frequency is: firstly, the inductor current does not exceed the saturation current to avoid current runaway; secondly, the switching frequency needs to be adapted to the characteristics of the MOSFET; and thirdly, the output ripple voltage cannot interfere with the subsequent circuit. In this way, the first switch Q1, the first inductor L1 and the second capacitor C2 form a new BUCK circuit so that the output voltage VO does not exceed the set value; and the first switch Q1 does not require large power consumption, so there is no need to use a high-power MOSFET or heat dissipation measures, which is beneficial to reducing costs.

[0055] It should be noted that, as Figure 2 and Figure 3The hardware structure of the overvoltage protection circuit 100 shown is only an example, and the overvoltage protection circuit 100 may have more or fewer components than those shown in the figure, may combine two or more components, or may have different component configurations. The various components shown in the figure may be implemented in hardware, software, or a combination of hardware and software, including one or more signal processing and / or application-specific integrated circuits.

[0056] For example, in some embodiments, such as Figure 4 As shown, the overvoltage protection circuit 100 also includes a voltage divider circuit 150, which is electrically connected to the output terminal and the controller 140 respectively.

[0057] The overvoltage protection circuit 100 is configured such that: the voltage divider circuit 150 divides the output voltage VO and outputs a detection voltage to the controller 140; in response to the detection voltage being greater than a second voltage threshold, the controller 140 outputs a control signal at a second level to control the first switch circuit 110 to turn off, wherein when the output voltage VO is greater than a third voltage threshold, the detection voltage is greater than the second voltage threshold, and the third voltage threshold is greater than the first voltage threshold.

[0058] The second voltage threshold is a reference voltage value set at the input of controller 140, used for comparison with the detected voltage after voltage division. It is the equivalent value of the third voltage threshold mapped to the detection node (i.e., the input of controller 140) through the same voltage divider network (i.e., voltage divider circuit 150). The third voltage threshold being greater than the first voltage threshold means that the overvoltage protection threshold triggered by software (i.e., the third voltage threshold) is greater than the overvoltage protection threshold triggered by hardware (i.e., the first voltage threshold). This ensures an absolute safety baseline through hardware and enables intelligent and recoverable system management through software, ultimately improving product reliability and safety. Furthermore, by setting up the voltage divider circuit 150, controller 140 is prevented from directly experiencing high voltage, which also improves reliability.

[0059] Thus, when an overvoltage fault occurs and the output voltage VO increases to a level greater than the third voltage threshold, the detected voltage is greater than the second voltage threshold. The control signal output by the controller 140 is at the second level to control the first switching circuit 110 to turn off, thereby effectively realizing overvoltage protection and helping to reduce the risk of device damage.

[0060] In some embodiments, such as Figure 5 As shown, the voltage divider circuit 150 includes a ninth resistor R9 and a tenth resistor R10. The ninth resistor R9 and the tenth resistor R10 are connected in series between the output terminal and ground GND, and the connection node between the ninth resistor R9 and the tenth resistor R10 is electrically connected to the controller 140.

[0061] Specifically, after the controller 140 detects an abnormal output voltage VO based on the voltage at the connection node between the ninth resistor R9 and the tenth resistor R10 (i.e., when the detected voltage is greater than the second voltage threshold), the controller 140 adjusts the output control signal to the second level (low level in this embodiment) to turn off the first switch Q1, thereby achieving overvoltage protection.

[0062] This application also provides an electronic device, which includes the overvoltage protection circuit 100 in any embodiment of this application.

[0063] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

[0064] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An overvoltage protection circuit, characterized in that, include: The circuit consists of a first switching circuit, a voltage conversion circuit, a second switching circuit, and a controller. The first switching circuit is electrically connected between the input voltage and the voltage conversion circuit. The first switching circuit is also electrically connected to the controller and the second switching circuit. The voltage conversion circuit and the second switching circuit are electrically connected to the output terminal, and the voltage at the output terminal is the output voltage. The overvoltage protection circuit is configured as follows: In response to the control signal output by the controller being at a first level and the second switching circuit being turned off, the first switching circuit is turned on, and the voltage conversion circuit converts the input voltage into the output voltage. In response to the output voltage being greater than a first voltage threshold, the second switching circuit is turned on to turn off the first switching circuit, and the output voltage decreases until the output voltage decreases to less than or equal to the first voltage threshold. Then, the second switching circuit is turned off, the first switching circuit is turned on, and the output voltage increases.

2. The overvoltage protection circuit according to claim 1, characterized in that, The first switching circuit includes a first switch and a second switch; The first terminal of the first switch is electrically connected to the third terminal of the second switch, the second terminal of the first switch is electrically connected to the input voltage, the third terminal of the first switch is electrically connected to the voltage conversion circuit, the first terminal of the second switch is electrically connected to the controller and the second switch circuit, and the second terminal of the second switch is grounded.

3. The overvoltage protection circuit according to claim 2, characterized in that, The first switching circuit further includes a first resistor, a second resistor, a third resistor, and a fourth resistor; The first resistor is electrically connected between the third terminal of the first switch and the voltage conversion circuit; the second resistor is electrically connected between the first and second terminals of the first switch; the third resistor is electrically connected between the first terminal of the first switch and the third terminal of the second switch; and the fourth resistor is electrically connected between the first terminal of the second switch and the controller. The first switch is a PMOS transistor, and the second switch is an NPN transistor.

4. The overvoltage protection circuit according to claim 1, characterized in that, The voltage conversion circuit includes a first capacitor, a second capacitor, a first inductor, and a BUCK chip; The first capacitor is electrically connected between the power supply terminal and ground of the BUCK chip, the first inductor and the second capacitor are connected in series between the switching terminal and ground of the BUCK chip, and the connection node between the first inductor and the second capacitor is electrically connected to the output terminal.

5. The overvoltage protection circuit according to claim 4, characterized in that, The minimum value of the second capacitor is: ； Among them, C out I is the minimum value of the second capacitor. out The output current is T at the output terminal, r is the inductor current ripple coefficient, and T is the output current at the output terminal. on For the conduction period, T off For the shutdown period, V outripp This is the output ripple voltage.

6. The overvoltage protection circuit according to claim 4, characterized in that, The minimum value of the first capacitor is: ； Among them, C in I is the minimum value of the first capacitor. inmax V represents the maximum input current. inmin denoted as the minimum input voltage, and 'a' as the preset voltage coefficient.

7. The overvoltage protection circuit according to claim 1, characterized in that, The second switching circuit includes a Zener diode, a fifth resistor, a sixth resistor, a seventh resistor, and a third switch; The cathode of the Zener diode is electrically connected to the output terminal, the anode of the Zener diode is electrically connected to the first terminal of the fifth resistor, the second terminal of the fifth resistor is electrically connected to the first terminal of the sixth resistor and the first terminal of the seventh resistor, the second terminal of the sixth resistor and the second terminal of the third switch are both grounded, the second terminal of the seventh resistor is electrically connected to the first terminal of the third switch, and the third terminal of the third switch is electrically connected to the first switch circuit. The third switch is an NPN transistor.

8. The overvoltage protection circuit according to claim 7, characterized in that, The second switching circuit also includes an eighth resistor and a third capacitor; The eighth resistor and the third capacitor are connected in series between the third terminal of the third switch and the second terminal of the fifth resistor.

9. The overvoltage protection circuit according to any one of claims 1-8, characterized in that, The overvoltage protection circuit also includes a voltage divider circuit, which is electrically connected to the output terminal and the controller respectively. The overvoltage protection circuit is configured as follows: The voltage divider circuit divides the output voltage and outputs a detection voltage to the controller; In response to the detection voltage being greater than a second voltage threshold, the controller outputs a control signal at a second level to control the first switching circuit to turn off, wherein the detection voltage is greater than the second voltage threshold when the output voltage is greater than a third voltage threshold, and the third voltage threshold is greater than the first voltage threshold.

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

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