Overvoltage protection circuit and electronic product

Abstract

This application discloses an overvoltage protection circuit and an electronic product. The overvoltage protection circuit includes a controllable voltage regulator branch, a first switching branch, and a second switching branch. The controllable voltage regulator branch conducts when the input power supply voltage is greater than a first voltage threshold. The first switching branch conducts in response to the input power supply voltage when the controllable voltage regulator branch is conducting, outputting a first level signal. The second switching branch disconnects in response to the first level signal, disconnecting the connection between the input power supply and the load. After the controllable voltage regulator branch is conducting, the input power supply voltage decreases to less than or equal to a second voltage threshold and then disconnects. The first switching branch also disconnects when the controllable voltage regulator branch is disconnected. The second switching branch conducts in response to the input power supply voltage when the first switching branch is disconnected, establishing a connection between the input power supply and the load. Through the above method, overvoltage protection can be achieved while maintaining the stability of the load operation.

Description

Technical Field

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

[0002] When using electronic products, large fluctuations in the input voltage can cause the product to malfunction or even be damaged due to excessive input voltage. Therefore, overvoltage protection circuits need to be installed in electronic products to prevent them from being affected or damaged by excessive input voltage.

[0003] Currently, overvoltage clamping chips are commonly used in electronic products to achieve overvoltage protection. For example, ... Figure 1 As shown, when the microcontroller unit (MCU) detects an overvoltage input, it outputs an enable signal to the enable pin of the overvoltage clamping chip UA1 to enable the UA1 to operate. The overvoltage clamping chip UA1 controls its output voltage to be zero, thereby realizing the overvoltage protection function. Specifically, when the input power supply voltage is just higher than the overvoltage protection point, the internal switching module of the overvoltage clamping chip UA1 is open, disconnecting the power supply to the load; when the input power supply voltage is just lower than the overvoltage protection point, the internal switching module of the overvoltage clamping chip UA1 is closed, and power is supplied to the load.

[0004] However, if the input power supply voltage oscillates at the overvoltage protection point, the switching module inside the overvoltage clamping chip UA1 will continuously restart. The spike voltage and surge current generated during the switching process of the switching module will seriously affect the stability of the power supply to the downstream load. Summary of the Invention

[0005] This application aims to provide an overvoltage protection circuit and electronic product that can maintain the stability of load operation while achieving overvoltage protection.

[0006] To achieve the above objectives, in a first aspect, this application provides an overvoltage protection circuit, comprising:

[0007] A controllable voltage regulator branch is connected to the input power supply and is configured to turn on when the voltage of the input power supply is greater than a first voltage threshold.

[0008] The first switching branch is connected to the input power supply and the controllable voltage regulator branch respectively. The first switching branch is configured to turn on in response to the voltage of the input power supply when the controllable voltage regulator branch is turned on, so as to output a first level signal.

[0009] The second switch branch is connected to the first switch branch and is connected between the input power supply and the load. The second switch branch is configured to disconnect in response to a first level signal to disconnect the connection between the input power supply and the load.

[0010] The controllable voltage regulator branch is also configured to disconnect when the voltage of the input power supply decreases to less than or equal to a second voltage threshold after the controllable voltage regulator branch is turned on, wherein the second voltage threshold is less than the first voltage threshold.

[0011] The first switching branch is also configured to disconnect when the controllable voltage regulator branch is disconnected;

[0012] The second switching branch is also configured to turn on in response to the voltage of the input power supply when the first switching branch is off, so as to establish a connection between the input power supply and the load.

[0013] In one alternative embodiment, the controllable voltage regulator branch includes a resistor unit and a controllable voltage regulator unit;

[0014] The resistor unit is connected to the first switch branch and the controllable voltage regulator unit respectively. The resistor unit is configured to output a first current to the controllable voltage regulator unit when the first switch branch is turned on, so as to generate a first voltage on the controllable voltage regulator unit.

[0015] The controllable voltage regulator unit is configured to turn on when the voltage of the input power supply is greater than the first voltage threshold.

[0016] The controllable voltage regulator unit is further configured to disconnect when the voltage of the input power supply is less than or equal to a second voltage threshold after the controllable voltage regulator unit is turned on, wherein the second voltage threshold is the difference between the first voltage threshold and a third voltage threshold, and the third voltage threshold is obtained from the first voltage.

[0017] In one alternative embodiment, the first switch branch includes a first switch unit and a second switch unit;

[0018] The first terminal of the first switching unit is connected to the input power supply, the second terminal of the first switching unit is connected to the first terminal of the second switching unit, the second terminal of the second switching unit is connected to the second switching branch, and the third terminal of the first switching unit is connected to the controllable voltage regulator branch.

[0019] The first switching unit is configured to turn on in response to the voltage of the input power supply when the controllable voltage regulation branch is turned on, so as to establish a connection between the input power supply and the first terminal of the second switching unit.

[0020] The second switching unit is configured to turn on when connected to the input power supply to output a first level signal.

[0021] In one alternative embodiment, the first switching unit includes a first resistor, a second resistor, a third resistor, and a first switching transistor;

[0022] The first end of the first resistor is connected to the input power supply. The second end of the first resistor is connected to the first end of the second resistor, the second end of the first switching transistor, and the second switching branch. The second end of the second resistor is connected to the first end of the third resistor and the first end of the first switching transistor. The second end of the third resistor is connected to the controllable voltage regulation branch. The third end of the first switching transistor is connected to the first end of the second switching unit.

[0023] In one alternative embodiment, the second switching unit includes a fourth resistor, a fifth resistor, a first capacitor, and a second switching transistor;

[0024] The first end of the fourth resistor is connected to the second end of the first switching unit. The second end of the fourth resistor is connected to the first end of the first capacitor, the first end of the fifth resistor, and the first end of the second switching transistor. The second ends of the first capacitor, the fifth resistor, and the second switching transistor are all grounded. The third end of the second switching transistor is connected to the second switching branch.

[0025] In one alternative embodiment, the second switch branch includes a third switch unit and a fourth switch unit;

[0026] The first end of the third switch unit is connected to the first switch branch, the second end of the third switch unit is connected to the first end of the fourth switch unit, the second end of the fourth switch unit is connected to the input power supply, and the third end of the fourth switch unit is connected to the load.

[0027] The third switching unit is configured to open in response to the first level signal;

[0028] The fourth switching unit is configured to disconnect when the third switching unit is disconnected, thereby disconnecting the connection between the input power supply and the load.

[0029] In one alternative embodiment, the third switching unit includes a sixth resistor, a second capacitor, and a third switching transistor;

[0030] The first end of the sixth resistor is connected to the first switch branch, the second end of the sixth resistor is connected to the first end of the second capacitor and the first end of the third switch transistor respectively, the second end of the second capacitor and the second end of the third switch transistor are both grounded, and the third end of the third switch transistor is connected to the fourth switch unit.

[0031] In one alternative embodiment, the fourth switching unit includes a seventh resistor, an eighth resistor, a Zener diode, a third capacitor, and a fourth switching transistor.

[0032] The first end of the seventh resistor is connected to the third switching unit. The second end of the seventh resistor is connected to the anode of the Zener diode, the first end of the eighth resistor, the first end of the third capacitor, and the first end of the fourth switching transistor. The cathode of the Zener diode, the second end of the eighth resistor, the second end of the third capacitor, and the second end of the fourth switching transistor are all connected to the input power supply. The third end of the fourth switching transistor is connected to the load.

[0033] In one alternative embodiment, the controllable voltage regulator unit includes a ninth resistor, a tenth resistor, and a controllable voltage source;

[0034] The first end of the ninth resistor is connected to the input power supply. The second end of the ninth resistor is connected to the first end of the tenth resistor, the reference end of the controllable voltage regulator, and the resistor unit. The anode of the controllable voltage regulator and the second end of the tenth resistor are both grounded. The cathode of the controllable voltage regulator is connected to the first switch branch.

[0035] In one alternative embodiment, the resistor unit includes an eleventh resistor;

[0036] The first end of the eleventh resistor is connected to the first switch branch, and the second end of the eleventh resistor is connected to the controllable voltage regulator unit.

[0037] Secondly, this application provides an electronic product including the overvoltage protection circuit described above.

[0038] The beneficial effects of this application are as follows: The overvoltage protection circuit provided by this application includes a controllable voltage regulator branch, a first switching branch, and a second switching branch. The controllable voltage regulator branch is connected to the input power supply. The first switching branch is connected to both the input power supply and the controllable voltage regulator branch. The second switching branch is connected to the first switching branch and is connected between the input power supply and the load. When an overvoltage occurs in the input power supply, the voltage of the input power supply exceeds a first voltage threshold. At this time, the controllable voltage regulator branch is turned on. Subsequently, the first switching branch turns on in response to the voltage of the input power supply. The first switching branch outputs a first-level signal to the second switching branch. The second switching branch is turned off to disconnect the connection between the input power supply and the load, thereby achieving overvoltage protection. Furthermore, after the controllable voltage regulator branch is turned on, if the input voltage can gradually recover, that is, the input voltage gradually decreases and decreases to less than or equal to the second voltage threshold, the controllable voltage regulator branch is turned off again. Then, the first switching branch is also turned off. When the second switching branch is turned on, the connection between the input power supply and the load is established, allowing the input power supply to normally power the load. Because the first and second voltage thresholds are different, the voltage points at which the controllable voltage regulation branch turns on and off are different. Therefore, even if the input power supply voltage oscillates at the overvoltage protection point, it will not cause the first and second switching branches to continuously turn on and off, thus avoiding the generation of voltage spikes and inrush currents as seen in related technologies, thereby helping to maintain the stability of the load operation. Attached Figure Description

[0039] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0040] Figure 1 This is a schematic diagram of a structure that implements overvoltage protection in related technologies;

[0041] Figure 2 This is a schematic diagram of the overvoltage protection circuit provided in one embodiment of this application;

[0042] Figure 3 This is a schematic diagram of the overvoltage protection circuit provided in another embodiment of this application;

[0043] Figure 4 A schematic diagram of the overvoltage protection circuit provided in another embodiment of this application;

[0044] Figure 5 This is a schematic diagram of the overvoltage protection circuit provided in one embodiment of this application. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0046] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the overvoltage protection circuit provided in an embodiment of this application. Figure 2 As shown, the overvoltage protection circuit 100 includes a controllable voltage regulation branch 10, a first switch branch 20, and a second switch branch 30.

[0047] The controllable voltage regulator branch 10 is connected to the input power supply VIN. The first switch branch 20 is connected to both the input power supply VIN and the controllable voltage regulator branch 10. The second switch branch 30 is connected to the first switch branch 20 and is connected between the input power supply VIN and the load 200.

[0048] Specifically, the controllable voltage regulator branch 10 is configured to turn on when the voltage of the input power supply VIN is greater than a first voltage threshold. The first switching branch 20 is configured to turn on in response to the voltage of the input power supply VIN when the controllable voltage regulator branch 10 is on, to output a first level signal. The second switching branch 30 is configured to turn off in response to the first level signal, to disconnect the connection between the input power supply VIN and the load 200. The controllable voltage regulator branch 10 is also configured to turn off when the voltage of the input power supply VIN decreases to less than or equal to a second voltage threshold after the controllable voltage regulator branch 10 is turned on. The second voltage threshold is less than the first voltage threshold. The first switching branch 20 is also configured to turn off when the controllable voltage regulator branch 10 is turned off. The second switching branch 30 is also configured to turn on in response to the voltage of the input power supply VIN when the first switching branch 20 is turned off, to establish a connection between the input power supply VIN and the load 200.

[0049] In this embodiment, the first voltage threshold is used to determine whether the voltage of the input power supply VIN is overvoltage, and the second voltage threshold is used to determine whether the input power supply VIN can be restored to supply power to the load 200.

[0050] In practical applications, when an overvoltage occurs at the input power supply VIN, exceeding a first voltage threshold, the controllable voltage regulator branch 10 is activated. Subsequently, the first switching branch 20 activates in response to the input power supply VIN voltage. The first switching branch 20 outputs a first-level signal to the second switching branch 30. Upon receiving the first-level signal, the second switching branch 30 disconnects, breaking the connection between the input power supply VIN and the load 200. This process achieves overvoltage protection.

[0051] Subsequently, after the controllable voltage regulator branch 10 is turned on, if the input voltage VIN gradually recovers (i.e., the input voltage VIN gradually decreases and decreases to less than or equal to the second voltage threshold), the controllable voltage regulator branch 10 is turned off again. Then, the first switching branch 20 is also turned off. The second switching branch 30 is turned on, and the connection between the input power supply VIN and the load 200 is established, allowing the input power supply VIN to normally power the load 200. In this embodiment, because the first voltage threshold and the second voltage threshold are different, the voltage nodes at which the controllable voltage regulator branch is turned on and off are different (i.e., the controllable voltage regulator branch only turns on when the voltage of the input power supply VIN is greater than the first voltage threshold, and only turns off when the voltage of the input power supply VIN is less than or equal to the second voltage threshold). Therefore, even if the voltage of the input power supply VIN oscillates at the overvoltage protection point, it will not cause the first switching branch 20 and the second switching branch 30 to continuously turn on and off, thus avoiding the generation of voltage spikes and surge currents as in related technologies, thereby helping to maintain the stability of the load operation.

[0052] In one embodiment, such as Figure 3 As shown, the controllable voltage regulator branch 10 includes a controllable voltage regulator unit 11 and a resistor unit 12.

[0053] The resistor unit 12 is connected to the first switch branch 20 and the controllable voltage regulator unit 11, respectively.

[0054] Specifically, resistor unit 11 is configured to output a first current to controllable voltage regulator unit 11 when the first switch branch 20 is turned on, so as to generate a first voltage at the connection node between controllable voltage regulator unit 11 and resistor unit 12. Controllable voltage regulator unit 11 is configured to turn on when the voltage of input power supply VIN is greater than a first voltage threshold. Controllable voltage regulator unit 11 is also configured to turn off when the voltage of input power supply VIN is less than or equal to a second voltage threshold after controllable voltage regulator unit 11 is turned on. The second voltage threshold is the difference between the first voltage threshold and a third voltage threshold. The third voltage threshold is obtained from the first voltage; specifically, when controllable voltage regulator unit 11 is turned on, the voltage division of the third voltage threshold across controllable voltage regulator unit 11 is the first voltage.

[0055] In this embodiment, when the input power supply VIN is overvoltaged (i.e., the input power supply VIN voltage is greater than a first voltage threshold) and the first switching branch 20 is turned on, the input power supply VIN is connected to the controllable voltage regulator branch 10 through the first switching branch 20 and the resistor unit 12 to generate a first current in the resistor unit 12. The first current is input to the controllable voltage regulator unit 11 to generate a first voltage in the controllable voltage regulator unit 11.

[0056] Before the addition of resistor unit 12, the voltage applied to the controllable voltage regulator unit 11 is denoted as the second voltage. When the input power supply VIN voltage decreases to equal the first voltage threshold, the second voltage is insufficient to keep the controllable voltage regulator unit 11 on, and the controllable voltage regulator unit 11 will turn off.

[0057] With the addition of resistor unit 12, the voltage applied to the controllable voltage regulator unit 11 includes not only the second voltage but also the first voltage. When the input power supply VIN voltage decreases to equal the first voltage threshold, the voltage applied to the controllable voltage regulator unit 11 is the sum of the first voltage and the second voltage, which is sufficient to keep the controllable voltage regulator unit 11 on. Only when the input power supply VIN voltage continues to decrease to less than or equal to the second voltage threshold, and the sum of the first voltage and the second voltage is insufficient to keep the controllable voltage regulator unit 11 on, will the controllable voltage regulator unit 11 turn off.

[0058] In related technologies, with Figure 1Taking the overvoltage clamping chip UA1 as an example, when the input power supply VIN voltage is just higher than the overvoltage protection point, the internal switching module of the overvoltage clamping chip UA1 disconnects, disconnecting the power supply to load 200; when the input power supply VIN voltage is just lower than the overvoltage protection point, the internal switching module of the overvoltage clamping chip UA1 closes, starting to supply power to load 200. If the input power supply VIN voltage oscillates at the overvoltage protection point, the internal switching module of the overvoltage clamping chip UA1 continuously restarts, and the spike voltage and surge current generated during the switching process of the switching module seriously affect the stability of the power supply to the downstream load 200.

[0059] In the embodiments of this application, two threshold voltages can be constructed by setting the resistor unit 12. The first threshold voltage is a first voltage threshold, which is used to determine whether the voltage of the input power supply VIN is overvoltage. The second threshold voltage is a second voltage threshold, which is used to determine whether the input power supply VIN can recover to supply power to the load 200. Furthermore, the first voltage threshold is greater than the second voltage threshold. That is, the first voltage threshold and the second voltage threshold are different, forming a hysteresis comparison process. Therefore, even if the voltage of the input power supply VIN oscillates at the overvoltage protection point, it will not cause the first switch branch 20 and the second switch branch 30 to continuously turn on and off, and thus will not generate peak voltage and surge current as in related technologies, thereby helping to maintain the stability of the load operation.

[0060] Understandable, such as Figure 3 The 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.

[0061] For example, such as Figure 4 As shown, in one embodiment, the first switch branch 20 includes a first switch unit 21 and a second switch unit 22.

[0062] In this circuit, the first terminal of the first switching unit 21 is connected to the input power supply VIN; the second terminal of the first switching unit 21 is connected to the first terminal of the second switching unit 22 and the first terminal of the resistor unit 12; the second terminal of the second switching unit 22 is connected to the first terminal of the second switching branch 30; the third terminal of the first switching unit 21 is connected to the second terminal of the second switching branch 30; and the fourth terminal of the first switching unit 21 is connected to the second terminal of the controllable voltage regulator branch 10. The first terminal of the first switching unit 21 is the first terminal of the first switching branch 20; the second terminal of the first switching unit 21 is the second terminal of the first switching branch 20; the second terminal of the second switching unit 22 is the third terminal of the first switching branch 20; the third terminal of the first switching unit 21 is the fourth terminal of the first switching branch 20; and the fourth terminal of the first switching unit 21 is the fifth terminal of the first switching branch 20.

[0063] Specifically, the first switching unit 21 is configured to turn on in response to the voltage of the input power supply VIN when the controllable voltage regulator branch 10 is turned on, thereby establishing a connection between the input power supply VIN and the first terminal of the second switching unit 22. Furthermore, when the first switching unit 21 is turned on, the input power supply VIN is input to the controllable voltage regulator branch 10 through the first switching unit 21 and the resistor unit 12, thereby generating a first voltage on the controllable voltage regulator branch 10. The first switching unit 21 is also configured to turn off when the controllable voltage regulator branch 10 is turned off, thereby disconnecting the connection between the input power supply VIN and the first terminal of the second switching unit 22.

[0064] The second switching unit 22 is configured to be turned on when its first terminal is connected to the input power supply VIN, so as to output a first-level signal. The second switching unit 22 is also configured to be turned off when its first terminal is not connected to the input power supply VIN, so as to output a second-level signal to the second switching branch 30 based on the voltage of the input power supply VIN. The second-level signal and the first-level signal are signals of different levels; for example, if the first-level signal is a low-level signal, then the second-level signal is a high-level signal.

[0065] In this embodiment, by setting the first switch branch 20 as the first switch unit 21 and the second switch unit 22, a first voltage is generated on the controllable voltage regulation branch 10 to realize the hysteresis comparison process and maintain the stability of the load 200; the second switch branch 30 is also controlled to control the energization and de-energization of the load 200.

[0066] In another embodiment, the second switch branch 30 includes a third switch unit 31 and a fourth switch unit 32.

[0067] Specifically, the first end of the third switch unit 31 is connected to the third end of the first switch branch 20, the second end of the third switch unit 31 is connected to the first end of the fourth switch unit 32, the second end of the fourth switch unit 32 is connected to the input power supply VIN, the third end of the fourth switch unit 32 is connected to the load 200, and the third end of the third switch unit 31 is connected to the third end of the first switch branch 20. The first end of the third switch unit 31 is also the first end of the second switch branch 30, the third end of the third switch unit 31 is also the second end of the second switch branch 30, and the second end of the fourth switch unit 32 is also the third end of the second switch branch 30.

[0068] Specifically, the third switching unit 31 is configured to open in response to a first level signal. The third switching unit 31 is also configured to turn on in response to a second level signal.

[0069] The fourth switching unit 32 is configured to disconnect when the third switching unit 31 is open, thereby disconnecting the connection between the input power supply VIN and the load 200. The fourth switching unit 32 is also configured to turn on when the third switching unit 31 is on, thereby establishing the connection between the input power supply VIN and the load 200.

[0070] In this embodiment, by setting the second switch branch 30 as the third switch unit 31 and the fourth switch unit 32, the third switch unit 31 can enhance the driving capability of the fourth switch unit 32, thereby driving the fourth switch unit 32 to conduct and disconnect stably, thus maintaining the load 200 to receive and lose power stably, thereby improving the stability and reliability of the load 200.

[0071] Please refer to Figure 5 , Figure 5 An example circuit structure of an overvoltage protection circuit 100 is shown in the figure.

[0072] In one embodiment, such as Figure 5 As shown, the controllable voltage regulator unit 11 includes a ninth resistor R9, a tenth resistor R10, and a controllable voltage regulator U1.

[0073] In this circuit, the first terminal of the ninth resistor R9 is connected to the input power supply VIN. The second terminal of the ninth resistor R9 is connected to the first terminal of the tenth resistor R10, the reference terminal (pin 2 of the controllable voltage regulator U1), and the resistor unit 12. The anode (pin 1 of the controllable voltage regulator U1) and the second terminal of the tenth resistor R10 are both grounded to GND. The cathode (pin 3 of the controllable voltage regulator U1) is connected to the first switch branch 20. The second terminal of the ninth resistor R9 is the first terminal of the controllable voltage regulator unit 11, the anode of the controllable voltage regulator U1 is the second terminal of the controllable voltage regulator unit 11, and the first terminal of the ninth resistor R9 is the third terminal of the controllable voltage regulator unit 11.

[0074] Specifically, the ninth resistor R9 and the tenth resistor R10 are used to divide the voltage of the input power supply VIN. The voltage across the tenth resistor R10 is the voltage at the reference terminal of the controllable voltage regulator U1. In some embodiments, the controllable voltage regulator U1 can be a controllable precision voltage regulator of model TL431. The TL431 has a pair of three-terminal comparators, one of which is connected to a reference voltage source. When the voltage at the reference terminal of the TL431 is greater than the voltage of the reference voltage source (typically 2.5V), the anode and cathode of the TL431 are connected, and the corresponding controllable voltage regulator unit 11 is turned on; when the voltage at the reference terminal of the TL431 is less than or equal to the voltage of the reference voltage source, the anode and cathode of the TL431 are disconnected, and the corresponding controllable voltage regulator unit 11 is turned off.

[0075] In one embodiment, the first switching unit 21 includes a first resistor R1, a second resistor R2, a third resistor R3, and a first switching transistor Q1.

[0076] The first end of the first resistor R1 is connected to the input power supply VIN. The second end of the first resistor R1 is connected to the first end of the second resistor R2, the second end of the first switch Q1, and the second switch branch 30. The second end of the second resistor R2 is connected to the first end of the third resistor R3 and the first end of the first switch Q1. The second end of the third resistor R3 is connected to the controllable voltage regulator branch 10. The third end of the first switch Q1 is connected to the first end of the second switch unit 22.

[0077] Wherein, the first end of the first resistor R1 is the first end of the first switching unit 21, the third end of the first switching transistor Q1 is the second end of the first switching unit 21, the second end of the first switching transistor Q1 is the third end of the first switching unit 21, and the second end of the third resistor R3 is the fourth end of the first switching unit 21.

[0078] In this embodiment, the first resistor R1 and the second resistor R2 can limit the current input to the first terminal of the first switch Q1. When the controllable voltage regulator U1 is turned on, the voltage across the second resistor R2 provides the on-state voltage drop for the first switch Q1. Furthermore, the first resistor R1, the second resistor R2, and the third resistor R3 can limit the current input to the controllable voltage regulator U1.

[0079] In this embodiment, the first switching transistor Q1 is a PNP transistor. The base of the PNP transistor is the first terminal of the first switching transistor Q1, the emitter of the PNP transistor is the second terminal of the first switching transistor Q1, and the collector of the PNP transistor is the third terminal of the first switching transistor Q1.

[0080] In addition, the first switch Q1 can be any controllable switch, such as an insulated gate bipolar transistor (IGBT) device, an integrated gate commutated thyristor (IGCT) device, a gate turn-off thyristor (GTO) device, a silicon controlled rectifier (SCR) device, a junction gate field-effect transistor (JFET) device, a MOS controlled thyristor (MCT) device, etc.

[0081] In one embodiment, the second switching unit 22 includes a fourth resistor R4, a fifth resistor R5, a first capacitor C1, and a second switching transistor Q2.

[0082] The first end of the fourth resistor R4 is connected to the second end of the first switching unit 21. The second end of the fourth resistor R4 is connected to the first end of the first capacitor C1, the first end of the fifth resistor R5 and the first end of the second switching transistor Q2 respectively. The second ends of the first capacitor C1, the fifth resistor R5 and the second switching transistor Q2 are all grounded to GND. The third end of the second switching transistor Q2 is connected to the second switching branch 30.

[0083] Among them, the first end of the fourth resistor R4 is the first end of the second switching unit 22, and the third end of the second switching transistor Q2 is the second end of the second switching unit 22.

[0084] Specifically, the fourth resistor R4 and the fifth resistor R5 are used for voltage division to provide the voltage drop required for the second switch Q2 to conduct. The fourth resistor R4 is also used for current limiting. The first capacitor C1 is used for energy storage to maintain the stability of the voltage at the first terminal of the second switch Q2.

[0085] In this embodiment, the second switch Q2 is an NPN transistor. The base of the NPN transistor is the first terminal of the second switch Q2, the emitter of the NPN transistor is the second terminal of the second switch Q2, and the collector of the NPN transistor is the third terminal of the second switch Q2.

[0086] In addition, the second switch Q2 can be any controllable switch, such as an insulated gate bipolar transistor (IGBT) device, an integrated gate commutated thyristor (IGCT) device, a gate turn-off thyristor (GTO) device, a silicon controlled rectifier (SCR) device, a junction gate field-effect transistor (JFET) device, a MOS controlled thyristor (MCT) device, etc.

[0087] In one embodiment, the third switching unit 31 includes a sixth resistor R6, a second capacitor C2, and a third switching transistor Q3.

[0088] The first end of the sixth resistor R6 is connected to the first switch branch 20. The second end of the sixth resistor R6 is connected to the first end of the second capacitor C2 and the first end of the third switch Q3. The second end of the second capacitor C2 and the second end of the third switch Q3 are both grounded to GND. The third end of the third switch Q3 is connected to the fourth switch unit 32.

[0089] Among them, the first terminal of the third switch transistor Q3 is the first terminal of the third switch unit 31, the third terminal of the third switch transistor Q3 is the second terminal of the third switch unit 31, and the first terminal of the sixth resistor R6 is the third terminal of the third switch unit 31.

[0090] Specifically, the sixth resistor R6 is used for current limiting. The second capacitor C2 is used for energy storage.

[0091] In this embodiment, the third switch Q3 is an NPN transistor. The base of the NPN transistor is the first terminal of the third switch Q3, the emitter of the NPN transistor is the second terminal of the third switch Q3, and the collector of the NPN transistor is the third terminal of the third switch Q3.

[0092] In addition, the third switch Q3 can be any controllable switch, such as an insulated gate bipolar transistor (IGBT) device, an integrated gate commutated thyristor (IGCT) device, a gate turn-off thyristor (GTO) device, a silicon controlled rectifier (SCR) device, a junction gate field-effect transistor (JFET) device, a MOS controlled thyristor (MCT) device, etc.

[0093] In one embodiment, the fourth switching unit 32 includes a seventh resistor R7, an eighth resistor R8, a Zener diode DW1, a third capacitor C3, and a fourth switching transistor Q4.

[0094] The first end of the seventh resistor R7 is connected to the third switch unit 31. The second end of the seventh resistor R7 is connected to the anode of the Zener diode DW1, the first end of the eighth resistor R8, the first end of the third capacitor C3, and the first end of the fourth switch Q4. The cathode of the Zener diode DW1, the second end of the eighth resistor R8, the second end of the third capacitor C3, and the second end of the fourth switch Q4 are all connected to the input power supply VIN. The third end of the fourth switch Q4 is connected to the load 200.

[0095] Among them, the first end of the seventh resistor R7 is the first end of the fourth switching unit 32, the second end of the fourth switching transistor Q4 is the second end of the fourth switching unit 32, and the third end of the fourth switching transistor Q4 is the third end of the fourth switching unit 32.

[0096] Specifically, Zener diode DW1 is used to turn on when the input power supply VIN voltage is high, clamping the voltage difference between the second and first terminals of the fourth switch Q4 at the reverse conduction voltage drop of Zener diode DW1, thus protecting the fourth switch Q4. The eighth resistor R8 provides the on-state voltage drop for the fourth switch Q4. The third capacitor C3 stores energy.

[0097] In this embodiment, the fourth switch Q4 is a PMOS transistor. The gate of the PMOS transistor is the first terminal of the fourth switch Q4, the source of the PMOS transistor is the second terminal of the fourth switch Q4, and the drain of the PMOS transistor is the third terminal of the fourth switch Q4.

[0098] In addition, the fourth switch Q4 can be any controllable switch, such as an insulated gate bipolar transistor (IGBT) device, an integrated gate commutated thyristor (IGCT) device, a gate turn-off thyristor (GTO) device, a silicon controlled rectifier (SCR) device, a junction gate field-effect transistor (JFET) device, a MOS controlled thyristor (MCT) device, etc.

[0099] In one embodiment, the resistor unit 12 includes an eleventh resistor R11.

[0100] The first end of the eleventh resistor R11 is connected to the first switch branch 20, and the second end of the eleventh resistor R11 is connected to the controllable voltage regulator unit 11. The first end of the eleventh resistor R11 is the first end of the resistor unit 12, and the second end of the eleventh resistor R11 is the second end of the resistor unit 12.

[0101] The following are Figure 5 The principle of the circuit shown will be explained. Taking the reference voltage source in the controllable regulated voltage source U1 as an example, the voltage is 2.5V.

[0102] When the voltage of the input power supply VIN (denoted as Vin) does not exceed the overvoltage limit, the voltage of the input power supply VIN is less than or equal to the first voltage threshold (denoted as Vmax), i.e., Vin≤Vmax. Where Vmax=2.5×(1+r9 / / ra)(1), and ra=r10 / / (r11+r4+r5)(2). Where r4 is the resistance value of the fourth resistor R4, r5 is the resistance value of the fifth resistor R5, r9 is the resistance value of the ninth resistor R9, r10 is the resistance value of the tenth resistor R10, r11 is the resistance value of the eleventh resistor R11, r9 / / ra represents the total resistance after the ninth resistor R9 and ra are connected in parallel, and ra represents the total resistance after the sum of the fourth resistor R4, the fifth resistor R5, the eleventh resistor R11 and the tenth resistor R10 are connected in parallel.

[0103] When Vin ≤ Vmax, the voltage at the reference terminal of the controllable voltage regulator U1 (corresponding to the second voltage in the above embodiment, denoted as V2) is less than or equal to 2.5V, and the anode and cathode of the controllable voltage regulator U1 are disconnected. There is no voltage difference between the first and second terminals of the first switch Q1, and the first switch Q1 is turned off. By configuring the fourth resistor R4, the fifth resistor R5, the ninth resistor R9, and the eleventh resistor R11, the voltage between the first and second terminals of the second switch Q2 is made less than its on-state voltage drop, and the second switch Q2 is also turned off. Subsequently, the input power supply VIN charges the second capacitor C2 through the sixth resistor R6. When the voltage on the second capacitor C2 is greater than the on-state voltage drop of the third switch Q3, the third switch Q3 is turned on. The input power supply VIN, the third capacitor C3, the seventh resistor R7, and the third switch Q3 form a circuit, and the input power supply VIN charges the third capacitor C3. When the voltage on the third capacitor C3 is greater than the on-state voltage drop of the fourth switch Q4, the fourth switch Q4 is turned on. The input power supply VIN supplies power to the load 200 through the fourth switch Q4.

[0104] When an overvoltage occurs in the input power supply VIN (i.e., when Vin > Vmax), the voltage at the reference terminal of the controllable voltage regulator U1 exceeds 2.5V, and the anode and cathode of the controllable voltage regulator U1 conduct. The input power supply VIN, the first resistor R1, the second resistor R2, the third resistor R3, and the controllable voltage regulator U1 form a circuit. The voltage across the second resistor R2 is greater than the forward voltage drop of the first switch Q1, causing the first switch Q1 to conduct. Subsequently, the input power supply VIN charges the first capacitor C1 through the first switch Q1 and the fourth resistor R4. When the voltage across the first capacitor C1 exceeds the forward voltage drop of the second switch Q2, the second switch Q2 conducts. The first terminal of the third switch Q3 is grounded to GND through the second switch Q2, forcibly pulling the first terminal of the third switch Q3 low, causing the third switch Q3 to turn off. There is no voltage difference between the first and second terminals of the fourth switch Q4, so the fourth switch Q4 also turns off. The connection between the input power supply VIN and the load 200 is disconnected, and the load 200 loses power, thus realizing the overvoltage protection function.

[0105] In related technologies, overvoltage clamping chips are typically used to implement overvoltage protection. For example, ... Figure 1 The overvoltage clamping chip UA1 shown is used to implement overvoltage protection. Specifically, when the MCU detects an overvoltage in the input power supply VIN, it outputs an enable signal to the enable pin of the overvoltage clamping chip UA1 (i.e., pin 9 of the overvoltage clamping chip UA1) to enable the overvoltage clamping chip UA1 to operate. The overvoltage clamping chip UA1 controls its output voltage (i.e., voltage VOUT) to be zero, thereby realizing the overvoltage protection function.

[0106] However, the overvoltage clamping chip UA1 has a small overvoltage protection range and a small output current, so it is only suitable for applications where the voltage and current of the input power supply VIN are small. For example, the overvoltage clamping chip UA1 can be used for USB devices, which is not very practical.

[0107] In the embodiments of this application, by setting the parameters of the components in the overvoltage protection circuit 100 (such as the components related to formulas (1) and (2)) to adjust the magnitude of the first voltage threshold, the voltage of the input power supply VIN can be adjusted when overvoltage protection is implemented. Therefore, different first voltage thresholds can be set for different application scenarios to meet the needs of different applications. Compared with related technologies, the overvoltage protection circuit 100 has a larger overvoltage protection range, which can increase the applicable application scenarios and improve practicality.

[0108] Secondly, regarding related technologies, for example Figure 1The circuit structure is shown. The pin definitions and packages of the overvoltage clamping chip UA1 produced by different manufacturers may differ, making it difficult to find a suitable replacement when the UA1 chip is damaged in actual use. Furthermore, replacing the UA1 chip is costly. In contrast, this application uses common components, which are not only inexpensive but also easy to replace when damaged.

[0109] Furthermore, after Vin > Vmax, the input power supply VIN, the first resistor R1, the first switch Q1, the eleventh resistor R11, and the tenth resistor R10 form a loop, which can add a voltage to the tenth resistor R10. This voltage is the first voltage (denoted as V1) in the above embodiment. When the eleventh resistor R11 is not set, according to formula (1), if Vin decreases to equal Vmax, the voltage at the reference terminal of the controllable voltage regulator U1 is V2 (2.5V at this time). However, after setting the eleventh resistor R11, it is equivalent to adding V1 to the base without setting the eleventh resistor R11. That is, in this case, the voltage at the reference terminal of the controllable voltage regulator U1 is the sum of V2 and V1. Subsequently, when Vin decreases to equal Vmax, the voltage at the reference terminal of the controllable voltage regulator U1 is the sum of V2 (i.e., 2.5V) and V1, which is greater than 2.5V. The anode and cathode of the controllable voltage regulator U1 remain connected, and the high-voltage protection circuit cannot resume normal operation. Therefore, Vin needs to be reduced further to reduce V2 until the sum of V2 and V1 is less than or equal to 2.5V, at which point the anode and cathode of the controllable voltage regulator U1 are disconnected.

[0110] Assuming Vin decreases to equal VT (corresponding to the second voltage threshold in the above embodiment), the sum of V2 and V1 equals 2.5V, and the anode and cathode of the controllable voltage regulator U1 begin to disconnect. The third voltage threshold Vmin can be calculated from Vmin = V1 × (1 + r9 / / ra) (3). Vin first decreases to Vmax, and then from Vmax to VT. The difference between Vmax and VT is caused by V1, so this difference is Vmin, that is, Vmax - Vmin = VT. In summary, when the voltage Vin of the input power supply VIN decreases to less than or equal to the second voltage threshold VT, the controllable voltage regulator unit 11 disconnects. The second voltage threshold VT = the first voltage threshold Vmax - the third voltage threshold Vmin. The third voltage threshold Vmin is obtained from the first voltage V1, and the relationship between the third voltage threshold Vmin and the first voltage V1 is determined according to formula (3).

[0111] In this embodiment, by setting the eleventh resistor R11, two threshold voltages can be constructed. The first threshold voltage is the first voltage threshold Vmax, which is used to determine whether the input power supply VIN is overvoltage. The second threshold voltage is the second voltage threshold VT, which is used to determine whether the input power supply VIN can recover to supply power to the load 200. Furthermore, since the first voltage threshold Vmax and the second voltage threshold VT are different, a hysteresis comparison process can be formed. Therefore, even if the voltage of the input power supply VIN oscillates at the overvoltage protection point, it will not cause the first switching branch 20 and the second switching branch 30 to continuously turn on and off, and thus will not generate voltage spikes and surge currents as in related technologies, thereby helping to maintain the stability of the load 200 operation.

[0112] This application also provides an electronic product, which includes the overvoltage protection circuit 100 in any embodiment of this application.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this application as described above, which are not provided in detail for the sake of brevity; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for 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: A controllable voltage regulator branch is connected to an input power supply and is configured to conduct when the voltage of the input power supply is greater than a first voltage threshold. The first switching branch is connected to the input power supply and the controllable voltage regulator branch respectively. The first switching branch is configured to turn on in response to the voltage of the input power supply when the controllable voltage regulator branch is turned on, so as to output a first level signal. A second switch branch is connected to the first switch branch and is connected between the input power supply and the load. The second switch branch is configured to disconnect in response to the first level signal to disconnect the connection between the input power supply and the load. The controllable voltage regulator branch is further configured to disconnect when the voltage of the input power supply decreases to less than or equal to a second voltage threshold after the controllable voltage regulator branch is turned on, wherein the second voltage threshold is less than the first voltage threshold. The first switching branch is also configured to disconnect when the controllable voltage regulator branch is disconnected; The second switch branch is also configured to turn on in response to the voltage of the input power supply when the first switch branch is off, so as to establish a connection between the input power supply and the load; The first switch branch includes a first switch unit and a second switch unit; The first terminal of the first switching unit is connected to the input power supply, the second terminal of the first switching unit is connected to the first terminal of the second switching unit, the second terminal of the second switching unit is connected to the second switching branch, and the third terminal of the first switching unit is connected to the controllable voltage regulator branch. The first switching unit is configured to turn on in response to the voltage of the input power supply when the controllable voltage regulator branch is turned on, so as to establish a connection between the input power supply and the first terminal of the second switching unit; The second switching unit is configured to be turned on when connected to the input power supply to output a first level signal; The first switching unit includes a first resistor, a second resistor, a third resistor, and a first switching transistor; The first end of the first resistor is connected to the input power supply, the second end of the first resistor is connected to the first end of the second resistor, the second end of the first switching transistor and the second switching branch respectively, the second end of the second resistor is connected to the first end of the third resistor and the first end of the first switching transistor respectively, the second end of the third resistor is connected to the controllable voltage regulation branch, and the third end of the first switching transistor is connected to the first end of the second switching unit. The second switch branch includes a third switch unit and a fourth switch unit; The first end of the third switch unit is connected to the first switch branch, the second end of the third switch unit is connected to the first end of the fourth switch unit, the second end of the fourth switch unit is connected to the input power supply, and the third end of the fourth switch unit is connected to the load. The third switching unit is configured to disconnect in response to the first level signal; The fourth switching unit is configured to disconnect when the third switching unit is disconnected, thereby disconnecting the connection between the input power supply and the load; The third switching unit includes a sixth resistor, a second capacitor, and a third switching transistor; The first end of the sixth resistor is connected to the first switch branch, the second end of the sixth resistor is connected to the first end of the second capacitor and the first end of the third switch tube respectively, the second end of the second capacitor and the second end of the third switch tube are both grounded, and the third end of the third switch tube is connected to the fourth switch unit. The fourth switching unit includes a seventh resistor, an eighth resistor, a Zener diode, a third capacitor, and a fourth switching transistor; The first end of the seventh resistor is connected to the third switching unit. The second end of the seventh resistor is connected to the anode of the Zener diode, the first end of the eighth resistor, the first end of the third capacitor, and the first end of the fourth switching transistor. The cathode of the Zener diode, the second end of the eighth resistor, the second end of the third capacitor, and the second end of the fourth switching transistor are all connected to the input power supply. The third end of the fourth switching transistor is connected to the load.

2. The overvoltage protection circuit according to claim 1, characterized in that, The controllable voltage regulator branch includes a resistor unit and a controllable voltage regulator unit; The resistor unit is connected to the first switch branch and the controllable voltage regulator unit respectively. The resistor unit is configured to output a first current to the controllable voltage regulator unit when the first switch branch is turned on, so as to generate a first voltage on the controllable voltage regulator unit. The controllable voltage regulator unit is configured to turn on when the voltage of the input power supply is greater than the first voltage threshold. The controllable voltage regulator unit is further configured to disconnect when the voltage of the input power supply is less than or equal to a second voltage threshold after the controllable voltage regulator unit is turned on, wherein the second voltage threshold is the difference between the first voltage threshold and a third voltage threshold, and the third voltage threshold is obtained from the first voltage.

3. The overvoltage protection circuit according to claim 1, characterized in that, The second switching unit includes a fourth resistor, a fifth resistor, a first capacitor, and a second switching transistor; The first end of the fourth resistor is connected to the second end of the first switching unit. The second end of the fourth resistor is connected to the first end of the first capacitor, the first end of the fifth resistor, and the first end of the second switching transistor. The second ends of the first capacitor, the fifth resistor, and the second switching transistor are all grounded. The third end of the second switching transistor is connected to the second switching branch.

4. The overvoltage protection circuit according to claim 2, characterized in that, The controllable voltage regulator unit includes a ninth resistor, a tenth resistor, and a controllable voltage source; The first end of the ninth resistor is connected to the input power supply, and the second end of the ninth resistor is connected to the first end of the tenth resistor, the reference end of the controllable voltage regulator, and the resistor unit. The anode of the controllable voltage regulator and the second end of the tenth resistor are both grounded, and the cathode of the controllable voltage regulator is connected to the first switch branch.

5. The overvoltage protection circuit according to claim 2, characterized in that, The resistor unit includes an eleventh resistor; The first end of the eleventh resistor is connected to the first switch branch, and the second end of the eleventh resistor is connected to the controllable voltage regulator unit.

6. An electronic product, characterized in that, Includes the overvoltage protection circuit as described in any one of claims 1-5.

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