Overvoltage protection circuit and electronic device

Abstract

The utility model provides a kind of overvoltage protection circuit and electronic equipment, overvoltage protection circuit includes: power end, output end, first voltage type switching device and first slow start circuit;Power end is used to access power supply voltage;Output end is used to connect load;The first end of first voltage type switching device is connected power end, second end connects output end;The input end of first slow start circuit is connected power end, output end connects the controlled end of first voltage type switching device;First voltage type switching device is used to the difference between voltage value at first end and voltage value at controlled end greater than first set threshold value, the passage between power end and output end is turned on;First slow start circuit is used to adjust voltage value at the controlled end of first voltage type switching device when power end accesses power supply voltage;Difference is greater than first set threshold value after first duration passes.This scheme makes first voltage type switching device turn on after first duration by first slow start circuit, reduces sharp peak voltage.

Description

Technical Field

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

[0002] In industrial environments where computer security requirements are increasingly stringent, it is necessary to promptly cut off the input voltage when there are large fluctuations in input voltage or when a high-voltage input power supply is accidentally connected and exceeds the tolerance range of downstream components, in order to avoid irreversible damage to the computer.

[0003] Existing voltage protection circuits output large inrush voltages (spiking voltages) and inrush currents when the switch is turned on or when an external voltage is initially applied, posing a risk of damaging subsequent circuits. Utility Model Content

[0004] The main purpose of this invention is to provide an overvoltage protection circuit and electronic device designed to reduce voltage spikes.

[0005] To achieve the above objectives, the present invention proposes an overvoltage protection circuit, which includes:

[0006] Power supply terminal, output terminal, first voltage-type switching device, and first soft-start circuit;

[0007] The power supply terminal is used to connect to the power supply voltage;

[0008] The output terminal is used to connect to the load;

[0009] The first terminal of the first voltage-type switching device is connected to the power supply terminal, and the second terminal is connected to the output terminal;

[0010] The input terminal of the first soft-start circuit is connected to the power supply terminal, and the output terminal is connected to the controlled terminal of the first voltage-type switching device.

[0011] The first voltage-type switching device is used to connect the path between the power supply terminal and the output terminal when the difference between the voltage value at the first terminal and the voltage value at the controlled terminal is greater than a first set threshold.

[0012] The first soft-start circuit is used to adjust the voltage value at the controlled terminal of the first voltage-type switching device when the power supply voltage is applied to the power supply terminal, so that the difference is greater than a first set threshold after a first time period.

[0013] Optionally, the overvoltage protection circuit further includes: a second voltage-type switching device and a second soft-start circuit;

[0014] The first terminal of the second voltage-type switching device is connected to the first terminal of the first voltage-type switching device, and the second terminal is connected to the controlled terminal of the first voltage-type switching device;

[0015] The input terminal of the second soft-start circuit is connected to the power supply terminal, and the output terminal is connected to the controlled terminal of the second voltage-type switching device.

[0016] The second voltage-type switching device is used to open the path between the first terminal of the first voltage-type switching device and the controlled terminal of the first voltage-type switching device when the difference between the voltage value at the first terminal of the second voltage-type switching device and the voltage value at the controlled terminal of the second voltage-type switching device is greater than a second set threshold.

[0017] The second soft-start circuit is used to increase the voltage value at the controlled terminal of the second voltage-type switching device when the power supply voltage is applied to the power supply terminal, so that the difference between the voltage value at the first terminal of the second voltage-type switching device and the voltage value at the controlled terminal of the second voltage-type switching device is less than a second set threshold after a second time period; the first time period is greater than the second time period.

[0018] Optionally, the overvoltage protection circuit further includes: a voltage detection and conduction circuit;

[0019] The first terminal of the voltage detection and conduction circuit is connected to the power supply terminal, the second terminal is grounded, and the output terminal is connected to the controlled terminal of the second voltage-type switching device.

[0020] The voltage detection circuit is used to open the path between the power supply terminal and ground when the power supply voltage is greater than or equal to a third preset threshold, so as to turn on the second voltage-type switching device and turn off the first voltage-type switching device.

[0021] Optionally, the voltage detection and conduction circuit includes: a switching device and a voltage divider circuit;

[0022] The first terminal of the switching device is connected to the controlled terminal of the second voltage-type switching device, and the second terminal is grounded; the first terminal of the voltage divider circuit is connected to the power supply terminal, the second terminal is grounded, and the output terminal is connected to the controlled terminal of the switching device.

[0023] The voltage divider circuit is used to divide the voltage value at the power supply terminal and output it to the controlled terminal of the switching device.

[0024] The switching device is used to connect the controlled terminal of the second voltage-type switching device to ground when the voltage value at the controlled terminal of the switching device is greater than or equal to the fourth preset threshold.

[0025] Optionally, the voltage divider circuit includes: a resistor voltage divider circuit and a first Zener diode;

[0026] The cathode of the first Zener diode is connected to the power supply terminal, and the anode is connected to the first terminal of the resistor voltage divider circuit; the second terminal of the resistor voltage divider circuit is grounded, and the output terminal is connected to the controlled terminal of the switching device.

[0027] Optionally, the first soft-start circuit includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, and a first diode;

[0028] The first end of the first resistor is connected to the power supply terminal and the first end of the first capacitor, and the second end is connected to the first end of the second resistor, the first end of the third resistor, and the anode of the first diode; the second end of the third resistor is grounded; the second end of the second resistor is connected to the cathode of the first diode, the second end of the first capacitor, and the first end of the fourth resistor; the second end of the fourth resistor is connected to the second end of the second voltage-type switching device.

[0029] Optionally, the second soft-start circuit includes: a fifth resistor, a second capacitor, and a second diode;

[0030] The fifth resistor and the second diode are connected in parallel; the cathode of the second diode is connected to the power supply terminal, and the anode is connected to the first terminal of the second capacitor and the controlled terminal of the second voltage-type switching device; the second terminal of the second capacitor is grounded.

[0031] Optionally, the time constant of the first RC circuit formed by the fifth resistor and the second capacitor is less than the time constant of the second RC circuit formed by the second resistor, the third resistor, and the first capacitor.

[0032] Optionally, the overvoltage protection circuit further includes: a positive power input terminal, a negative power input terminal, and a reverse connection protection circuit;

[0033] The reverse connection protection circuit includes: a sixth resistor, a second Zener diode, and an NMOS transistor;

[0034] The first end of the sixth resistor is connected to the positive input terminal of the power supply and the power supply terminal, and the second end is connected to the gate of the NMOS transistor and the cathode of the second Zener diode; the anode of the second Zener diode is connected to the source of the NMOS transistor and grounded; the drain of the NMOS transistor is connected to the negative input terminal of the power supply.

[0035] This invention also proposes an electronic device, which includes the overvoltage protection circuit.

[0036] This invention proposes an overvoltage protection circuit and electronic device. The overvoltage protection circuit includes: a power supply terminal, an output terminal, a first voltage-type switching device, and a first soft-start circuit. The power supply terminal is used to connect to a power supply voltage. The output terminal is used to connect to a load. A first terminal of the first voltage-type switching device is connected to the power supply terminal, and a second terminal is connected to the output terminal. The input terminal of the first soft-start circuit is connected to the power supply terminal, and the output terminal is connected to the controlled terminal of the first voltage-type switching device. The first voltage-type switching device is used to conduct the path between the power supply terminal and the output terminal when the voltage difference between the first terminal and the controlled terminal is greater than a first set threshold. The first soft-start circuit is used to adjust the voltage value at the controlled terminal of the first voltage-type switching device when the power supply voltage is connected to the power supply terminal, so that the difference is greater than the first set threshold after a first time period. This invention reduces voltage spikes by causing the voltage value output from the first soft-start circuit to the controlled terminal of the first voltage-type switching device to decrease slowly and then turn on the first voltage-type switching device after a first time period. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the existing technology of the overvoltage protection circuit of this utility model;

[0039] Figure 2 This is a schematic diagram of the first structure of the first embodiment of the overvoltage protection circuit of this utility model;

[0040] Figure 3 This is a second structural schematic diagram of the first embodiment of the overvoltage protection circuit of this utility model;

[0041] Figure 4 This is a schematic diagram of the first structure of the second embodiment of the overvoltage protection circuit of this utility model;

[0042] Figure 5 This is a schematic diagram of the second structure of the second embodiment of the overvoltage protection circuit of this utility model;

[0043] Figure 6 This is a schematic diagram of the first structure of the third embodiment of the overvoltage protection circuit of this utility model;

[0044] Figure 7 This is a schematic diagram of the second structure of the third embodiment of the overvoltage protection circuit of this utility model;

[0045] Figure 8 This is a schematic diagram of the third structure of the third embodiment of the overvoltage protection circuit of this utility model;

[0046] Figure 9 This is a schematic diagram of the fourth embodiment of the overvoltage protection circuit of this utility model.

[0047] Explanation of icon numbers:

[0048]

[0049]

[0050] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0051] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0052] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0053] In this utility model, unless otherwise explicitly specified and limited, the terms "connection," "fixing," etc., should be interpreted broadly. For example, "fixing" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0054] Furthermore, in this utility model, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0055] like Figure 1 As shown, Figure 1 A schematic diagram of an overvoltage protection circuit topology in the prior art is shown. Figure 1 In this design, when the input voltage is higher than approximately 5.7V, the transistor turns on, pulling the voltages across the drain and source of the MOSFET to the same level, thus turning off the output. The solution uses a Zener diode to stabilize the base voltage of the transistor at 5V, while the emitter voltage continuously rises. This ensures that the transistor turns on when the difference between the emitter and base voltages exceeds 0.7V, thereby controlling the MOSFET to turn off.

[0056] This scheme uses a transistor to directly control the switching of the MOSFET. However, in this scheme, the MOSFET is always in a conducting state when the circuit first starts working, and the input voltage undergoes a rise process (from 0V to the target voltage). During this process, voltage spikes are inevitably generated, posing a risk of damaging subsequent circuits. In addition, when the input power supply is reversed, this scheme cannot effectively prevent electronic components in the circuit from being damaged due to negative voltage.

[0057] This utility model proposes an overvoltage protection circuit, such as Figure 2 As shown, in the first embodiment, the overvoltage protection circuit includes:

[0058] Power supply terminal, output terminal, first voltage-type switching device Q1 and first soft-start circuit 10;

[0059] The power supply terminal is used to connect to the power supply voltage;

[0060] The output terminal is used to connect to the load;

[0061] The first terminal of the first voltage-type switching device Q1 is connected to the power supply terminal, and the second terminal is connected to the output terminal;

[0062] The input terminal of the first soft-start circuit 10 is connected to the power supply terminal, and the output terminal is connected to the controlled terminal of the first voltage-type switching device Q1.

[0063] The first voltage-type switching device Q1 is used to connect the path between the power supply terminal and the output terminal when the difference between the voltage value at the first terminal and the voltage value at the controlled terminal is greater than a first set threshold.

[0064] The first soft-start circuit 10 is used to adjust the voltage value at the controlled terminal of the first voltage-type switching device Q1 when the power supply voltage is applied to the power supply terminal, so that the difference is greater than a first set threshold after a first time period.

[0065] It should be noted that the first voltage-type switching device Q1 is disposed in the circuit between the power supply terminal and the output terminal; the first voltage-type switching device Q1 is used to conduct the path between the power supply terminal and the output terminal when the difference between the voltage value at the first terminal and the voltage value at the controlled terminal is greater than a first set threshold; the first voltage-type switching device Q1 can be a MOSFET, IGBT, or SIT, etc.; in particular, in one example, the first voltage-type switching device Q1 is a PMOS transistor.

[0066] Voltage spikes typically occur during the instantaneous power-on of a circuit or when a switching transistor rapidly turns on. To reduce voltage spikes, this embodiment requires reducing the turn-on speed of the switching transistor after the power supply voltage is applied to the power supply terminal.

[0067] The input terminal of the first soft-start circuit 10 is connected to the power supply terminal, and the output terminal is connected to the controlled terminal of the first voltage-type switching device Q1. When a power supply voltage is applied to the power supply terminal, the first soft-start circuit 10 outputs a voltage to the controlled terminal of the first voltage-type switching device Q1. It should be noted that the voltage amplitude output by the first soft-start circuit 10 to the controlled terminal of the first voltage-type switching device Q1 decreases for a period of time after the power supply voltage is applied to the power supply terminal. Because the voltage value at the controlled terminal of the first voltage-type switching device Q1 decreases, the voltage difference between the controlled terminal and the first terminal of the first voltage-type switching device Q1 increases accordingly. It is particularly important to note that the first terminal of the first voltage-type switching device Q1 is connected to the power supply terminal; when a power supply voltage is applied to the power supply terminal, the voltage at the first terminal is the power supply voltage. The first soft-start circuit 10 can slowly reduce the voltage value output to the controlled terminal of the first voltage-type switching device Q1 when the power supply voltage is applied to the power supply terminal, so that the conduction condition of the first voltage-type switching device Q1 is not met for a short period of time when the power supply voltage is initially applied to the power supply terminal; and the conduction condition of the first voltage-type switching device Q1 is met after the first period of time.

[0068] In one example, the output voltage of the first soft-start circuit 10 is less than the power supply voltage. The first set threshold is greater than zero; the first voltage-type switching device Q1 can be a PMOS transistor.

[0069] In another example, the first soft-start circuit 10 can output a voltage value greater than the power supply voltage; the first soft-start circuit 10 can boost the power supply voltage before outputting it. In this case, the first set threshold can be a negative number or a positive number.

[0070] The first set threshold can be determined by the R&D personnel based on the selected first voltage-type switching device Q1. As the voltage value output from the first soft-start circuit 10 to the controlled terminal of the first voltage-type switching device Q1 decreases, the difference between the power supply voltage and the voltage value at the controlled terminal increases accordingly until the difference exceeds the first threshold. It is easy to understand that the voltage output from the first soft-start circuit 10 requires a process to decrease, which will take a corresponding amount of time; specifically, the difference exceeds the first set threshold after a first time period. That is, it takes a first time period for the voltage value output from the first soft-start circuit 10 to decrease to a level that allows the first voltage-type switching device Q1 to conduct. This first time period can be determined by the R&D personnel.

[0071] Because the output voltage of the first soft-start circuit 10 decreases slowly in this embodiment, the first voltage-type switching device Q1 only turns on after a first period of time, reducing the voltage spikes generated at the moment of power-on. Furthermore, because the difference between the voltage at the first terminal of the first voltage-type switching device Q1 and the voltage at the controlled terminal increases slowly, and the conduction degree of the first voltage-type switching device Q1 is related to this difference, the slow turn-on of the first voltage-type switching device Q1 can reduce the voltage spikes generated when the first voltage-type switching device Q1 turns on rapidly.

[0072] This invention proposes an overvoltage protection circuit and electronic device. The overvoltage protection circuit includes: a power supply terminal, an output terminal, a first voltage-type switching device Q1, and a first soft-start circuit 10. The power supply terminal is used to connect to a power supply voltage. The output terminal is used to connect to a load. A first terminal of the first voltage-type switching device Q1 is connected to the power supply terminal, and a second terminal is connected to the output terminal. The input terminal of the first soft-start circuit 10 is connected to the power supply terminal, and the output terminal is connected to the controlled terminal of the first voltage-type switching device Q1. The first voltage-type switching device Q1 is used to conduct the path between the power supply terminal and the output terminal when the difference between the voltage value at the first terminal and the voltage value at the controlled terminal is greater than a first set threshold. The first soft-start circuit 10 is used to adjust the voltage value at the controlled terminal of the first voltage-type switching device Q1 when the power supply voltage is connected to the power supply terminal, so that the difference is greater than the first set threshold after a first time period. This invention reduces voltage spikes by slowly decreasing the voltage value output to the controlled terminal of the first voltage-type switching device Q1 through the first soft-start circuit 10, and then turning on the first voltage-type switching device Q1 after a first time period.

[0073] In one example, such as Figure 3 As shown, the first soft-start circuit 10 includes: a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, and a first diode D1;

[0074] The first end of the first resistor R1 is connected to the power supply terminal and the first end of the first capacitor C1, and the second end is connected to the first end of the second resistor R2, the first end of the third resistor R3 and the anode of the first diode D1; the second end of the third resistor R3 is grounded; the second end of the second resistor R2 is connected to the cathode of the first diode D1, the second end of the first capacitor C1 and the first end of the fourth resistor R4; the second end of the fourth resistor R4 is connected to the second end of the second voltage-type switching device Q2.

[0075] It should be noted that the second resistor R2, the third resistor R3, and the first capacitor C1 form a first RC circuit. The time constant of the first RC circuit is related to the values ​​of the second resistor R2, the third resistor R3, and the first capacitor C1. When a power supply voltage is applied to the power supply terminal, the controlled terminal of the first voltage-type switching device Q1 is connected to the power supply voltage through the first resistor R1. Initially, the voltage difference between the first terminal of the first voltage-type switch and the voltage at the controlled terminal is less than a first set threshold. Furthermore, after the power supply voltage is applied, the first capacitor C1 charges until charging is complete. During the charging process, the voltage difference across the first capacitor C1 increases, while the voltage at the first terminal of the first capacitor C1 remains constant due to the power supply voltage. Therefore, the voltage at the second terminal of the first capacitor C1 decreases, meaning the voltage at the controlled terminal of the first voltage-type switching device Q1 decreases. Additionally, based on the time constant, the time it takes for the voltage at the controlled terminal of the first voltage-type switching device Q1 to drop to meet the turn-on voltage condition of the first voltage-type switching device Q1 can be calculated. It is easy to understand that this can be taken as the first duration; and the difference is the same as the voltage value of the first capacitor C1. The first duration is also the charging time for the first capacitor C1 to charge to a voltage value corresponding to a first set threshold. The first diode D1 provides a discharge path for the charge in the first capacitor C1, achieving the purpose of quickly turning off the first voltage-type switching device Q1. When the first capacitor C1 is discharging, the current flows out from the first terminal of the first capacitor C1, passes through the first resistor R1, enters the anode of the first diode D1, and then reaches the second terminal of the first capacitor C1 from the cathode of the first diode D1.

[0076] The first resistor R1 and the third resistor R3 can form a resistor voltage divider circuit 320. After the first capacitor C1 is fully charged, the power supply voltage is divided and output to the first voltage-type switching device Q1. The fourth resistor R4 is a current-limiting resistor.

[0077] In the second embodiment of this utility model, as Figure 4 As shown, the overvoltage protection circuit further includes: a second voltage-type switching device Q2 and a second soft-start circuit 20;

[0078] The first terminal of the second voltage-type switching device Q2 is connected to the first terminal of the first voltage-type switching device Q1, and the second terminal is connected to the controlled terminal of the first voltage-type switching device Q1.

[0079] The input terminal of the second soft-start circuit 20 is connected to the power supply terminal, and the output terminal is connected to the controlled terminal of the second voltage-type switching device Q2.

[0080] The second voltage-type switching device Q2 is used to open the path between the first terminal of the first voltage-type switching device Q1 and the controlled terminal of the first voltage-type switching device Q1 when the difference between the voltage value at the first terminal of the second voltage-type switching device Q2 and the voltage value at the controlled terminal of the second voltage-type switching device Q2 is greater than a second set threshold.

[0081] The second soft-start circuit 20 is used to increase the voltage value at the controlled terminal of the second voltage-type switching device Q2 when the power supply voltage is applied to the power supply terminal, so that the difference between the voltage value at the first terminal of the second voltage-type switching device Q2 and the voltage value at the controlled terminal of the second voltage-type switching device Q2 is less than a second set threshold after a second time period; the first time period is greater than the second time period.

[0082] It should be noted that the second voltage-type switching device Q2 is disposed between the first terminal and the controlled terminal of the first voltage-type switching device Q1. Furthermore, the first voltage-type switching device Q1 conducts when the difference between the voltage value at the first terminal and the voltage value at the controlled terminal exceeds a first preset threshold. If the second voltage-type switching device Q2 conducts, the first terminal and the controlled terminal of the first voltage-type switching device Q1 are short-circuited, causing the first voltage-type switching device Q1 to turn off.

[0083] Therefore, in order to reduce the voltage spikes generated by the power supply voltage, this embodiment employs a second voltage-type switch Q2 that conducts during a second period of power supply voltage application, short-circuiting the first terminal and the controlled terminal of the first voltage-type switch Q1. After the second period, the second voltage-type switch Q2 turns off, and the first voltage-type switch Q1 is released from the short-circuit state.

[0084] The second soft-start circuit 20, when a power supply voltage is applied to the power supply terminal, begins to increase the voltage value output to the controlled terminal of the second voltage-type switching device Q2 until the difference between the voltage value at the first terminal of the second voltage-type switching device Q2 and the voltage value at the controlled terminal of the second voltage-type switching device Q2 exceeds a second set threshold. Specifically, the voltage value at the controlled terminal of the second voltage-type switching device Q2 is initially zero.

[0085] Furthermore, to ensure that the first voltage-type switch Q1 does not quickly turn on during the initial period after the power supply voltage is applied to the power supply terminal, thus preventing voltage spikes, the second voltage-type switch Q2 avoids the voltage value output by the first soft-start circuit 10 to the first voltage-type switch Q1. Therefore, to prevent the voltage value from being output by the first voltage-type switch Q1 to the first voltage-type switch Q1, the voltage difference between the first terminal of the first voltage-type switch Q1 and the controlled terminal is greater than a first set threshold when the first voltage-type switch Q1 is not short-circuited. However, since the second voltage-type switch Q2 is in the on state, the first voltage-type switch Q1 is in the off state. The first duration is greater than the second duration, ensuring that the second voltage-type switch Q2 changes from the on state to the off state before the first voltage-type switch Q1 meets the turn-on condition.

[0086] The second duration is determined by the R&D personnel. The second voltage-type switching device Q2 can be a MOSFET, IGBT, or SIT, etc.

[0087] In one example, such as Figure 5 As shown, the second soft-start circuit 20 includes: a fifth resistor R5, a second capacitor C2, and a second diode D2;

[0088] The fifth resistor R5 and the second diode D2 are connected in parallel; the cathode of the second diode D2 is connected to the power supply terminal, and the anode is connected to the first terminal of the second capacitor C2 and the controlled terminal of the second voltage-type switching device Q2; the second terminal of the second capacitor C2 is grounded.

[0089] The fifth resistor R5 and the second capacitor C2 form an RC circuit. When a power supply voltage is applied to the power supply terminal, the second capacitor C2 begins to charge. Since the first terminal of the second capacitor C2 is connected to the controlled terminal of the second voltage-type switching device Q2, and the second terminal is grounded, the voltage of the second capacitor C2 rises from zero during charging until the difference between the voltage at the first terminal of the second voltage-type switching device Q2 and the voltage at the controlled terminal of the second voltage-type switching device Q2 is less than a second set threshold. It is easy to understand that the time constant of the first RC circuit is related to the values ​​of the second resistor R2, the third resistor R3, and the first capacitor C1. Furthermore, based on this time constant, the time it takes for the voltage at the controlled terminal of the second voltage-type switching device Q2 to rise to meet the conduction voltage condition of the second voltage-type switching device Q2 can be calculated; this can be easily understood as the second duration.

[0090] The second diode D2 provides a discharge path for the charge in the second capacitor C2, enabling the rapid conduction of the second voltage-type switching device Q2. During discharge, the current flows from the first terminal of the second capacitor C2, through the second diode D2, the first resistor R1, and the third resistor R3, to the second terminal of the second capacitor C2.

[0091] Furthermore, the first duration is greater than the second duration. The first duration is positively correlated with the time constant of the first RC circuit, and the second duration is positively correlated with the time constant of the second RC circuit. In one example, the time constant of the first RC circuit can be used as the first duration, and the time constant of the second RC circuit can be used as the second duration. The time constant of the first RC circuit formed by the fifth resistor R5 and the second capacitor C2 is less than the time constant of the second RC circuit formed by the second resistor R2, the third resistor R3, and the first capacitor C1.

[0092] In the third embodiment, the overvoltage protection circuit further includes: a voltage detection and conduction circuit 30;

[0093] The first terminal of the voltage detection and conduction circuit 30 is connected to the power supply terminal, the second terminal is grounded, and the output terminal is connected to the controlled terminal of the second voltage-type switching device Q2.

[0094] The voltage detection circuit is used to open the path between the power supply terminal and ground when the power supply voltage is greater than or equal to a third set threshold, so as to turn on the second voltage-type switching device Q2 and turn off the first voltage-type switching device Q1.

[0095] like Figure 6As shown, it should be noted that the voltage detection circuit 30 is used to turn off the first voltage-type switching device Q1 when the power supply voltage exceeds the set threshold. Specifically, the output terminal of the voltage detection circuit is connected to the controlled terminal of the second voltage-type switching device Q2. When the power supply voltage is less than a third set threshold, the voltage detection circuit 30 is turned off; the controlled terminal of the second voltage-type switching device Q2 is affected by the second soft-start circuit 20. When the power supply voltage is detected to be greater than or equal to the third set threshold, the voltage detection circuit is turned on, thereby pulling down the potential of the controlled terminal of the second voltage-type switching device Q2 to ground; thus, the second voltage-type switching device Q2 is turned on, short-circuiting the first terminal and the controlled terminal of the first voltage-type switching device Q1. The first voltage-type switching device Q1 is turned off when its first terminal and its controlled terminal are short-circuited.

[0096] The third threshold value is determined by the R&D personnel.

[0097] In one example, such as Figure 7 As shown, the voltage detection and conduction circuit 30 includes: a switching device 310 and a voltage divider circuit 320;

[0098] The first terminal of the switching device 310 is connected to the controlled terminal of the second voltage-type switching device Q2, and the second terminal is grounded; the first terminal of the voltage divider circuit 320 is connected to the power supply terminal, the second terminal is grounded, and the output terminal is connected to the controlled terminal of the switching device 310.

[0099] The voltage divider circuit 320 is used to divide the voltage value at the power supply terminal and output it to the controlled terminal of the switching device 310.

[0100] The switching device 310 is used to connect the controlled terminal of the second voltage-type switching device Q2 to ground when the voltage value at the controlled terminal of the switching device 310 is greater than or equal to the fourth set threshold.

[0101] It should be noted that the switching device 310 is disposed between the controlled terminal of the second voltage-type switching device Q2 and ground. When the switching device 310 is turned on, the potential of the controlled terminal of the second power-type switching device 310 is pulled low to ground. The voltage divider circuit 320 divides the voltage value at the power supply terminal and outputs it to the controlled terminal of the switching device 310. When no power supply voltage is connected to the power supply terminal, the voltage at the power supply terminal is zero. The switching device 310 remains off when it receives zero voltage at its controlled terminal. When a power supply voltage is connected to the power supply terminal, the voltage after voltage division is greater than or equal to the fourth set threshold. The fourth set threshold is greater than or equal to the on-state voltage value corresponding to when the switching device 310 is turned on.

[0102] It is easy to understand that the voltage corresponding to the third set threshold is divided by the voltage divider circuit 320 and becomes the voltage corresponding to the fourth set threshold, which is then output to the switching device 310.

[0103] This example divides the voltage at the power supply terminal and selectively turns the switching device 310 on or off based on the presence of power supply voltage at the power supply terminal. When the power supply voltage is greater than or equal to a third set threshold, the switching device 310 turns on, thereby causing the second voltage-type switching device Q2 to turn on and the first voltage-type switching device Q1 to turn off.

[0104] The switching device 310 can be a transistor, MOSFET, SIT, thyristor, or IGBT, etc.

[0105] like Figure 8 As shown, the voltage divider circuit 320 includes: a resistor voltage divider circuit 320 and a first Zener diode VD1;

[0106] The cathode of the first Zener diode VD1 is connected to the power supply terminal, and the anode is connected to the first terminal of the resistor voltage divider circuit 320; the second terminal of the resistor voltage divider circuit 320 is grounded, and the output terminal is connected to the controlled terminal of the switching device 310.

[0107] The first Zener diode VD1 is positioned between the power supply terminal and the resistor divider circuit 320. The first Zener diode VD1 is used to handle a fixed voltage. The difference between the power supply voltage and the voltage across the first Zener diode VD1 is then divided by the resistor divider circuit 320.

[0108] In one example, the resistor divider circuit 320 includes a seventh resistor R7, an eighth resistor R8, and a third diode D3.

[0109] The first end of the seventh resistor R7 is connected to the anode of the first Zener diode VD1, and the second end is connected to the controlled terminal of the switching device 310, the first end of the eighth resistor R8, and the cathode of the third diode D3; the second end of the eighth resistor R8 is connected to the anode of the third diode D3 and grounded.

[0110] In another example, the first Zener diode VD1 has a stable voltage of 12V, and the switching device 310 is a transistor with a turn-on voltage of 0.7V. Assuming the overvoltage protection point voltage Vov is the voltage at which Q1 is triggered to turn on, then the overvoltage protection point voltage Vov = ((R8 + R9) * Ube / R9) + 12. Where Ube is the turn-on voltage of the transistor.

[0111] In the fourth embodiment, as Figure 9As shown, the overvoltage protection circuit further includes: a positive power input terminal, a negative power input terminal, and a reverse connection protection circuit;

[0112] The reverse connection protection circuit includes: a sixth resistor R6, a second Zener diode VD2, and an NMOS transistor;

[0113] The first end of the sixth resistor R6 is connected to the positive input terminal of the power supply and the power supply terminal, and the second end is connected to the gate of the NMOS transistor and the cathode of the second Zener diode VD2; the anode of the second Zener diode VD2 is connected to the source of the NMOS transistor and grounded; the drain of the NMOS transistor is connected to the negative input terminal of the power supply.

[0114] It should be noted that the overvoltage protection circuit has positive and negative voltages. The positive input terminal of the power supply is connected to the power supply terminal, and the positive input terminal is used to connect to the power supply voltage. The power supply terminal is used to connect to the voltage at the positive input terminal of the power supply. The negative input terminal of the power supply is used for grounding during normal operation.

[0115] The sixth resistor R6, the second Zener diode VD2, and the NMOS transistor are used to maintain the electrical circuit when the power supply voltage is applied to the positive input terminal, ensuring the negative input terminal is grounded so that the power supply voltage provides power to the load. Conversely, when the power supply voltage is applied to the negative input terminal, the electrical circuit is disconnected to prevent the power supply voltage from being output to the power supply terminal.

[0116] Specifically, the first end of the sixth resistor R6 is connected to the positive input terminal of the power supply and the power supply terminal, the second end is connected to the gate of the NMOS transistor, the drain of the NMOS transistor is connected to the negative input terminal of the power supply, and the source is grounded. When a power supply voltage is applied to the positive input terminal, the NMOS transistor is turned on, grounding the negative input terminal and establishing an electrical loop. When a power supply voltage is applied to the negative input terminal, the potential of the positive input terminal is zero. The NMOS transistor is turned off. Based on the above, this embodiment implements reverse connection protection.

[0117] The sixth resistor R6 is a current-limiting resistor. The second Zener diode VD2 is used to protect the NMOS transistor and prevent the voltage difference between the gate and source of the NMOS transistor from becoming too large.

[0118] In one example, the reverse connection protection circuit further includes: a fuse, a varistor RV, a third capacitor C3, and a fourth capacitor C4. The fuse is disposed between the positive input terminal of the power supply and the power supply terminal. The varistor RV and the third capacitor C3 are connected in parallel between the positive input terminal of the power supply and the negative input terminal of the power supply. The fourth capacitor C4 is connected in parallel with the second Zener diode VD2.

[0119] In addition, such as Figure 8As shown, the second soft-start circuit 20 may further include: a third Zener diode VD3, a ninth resistor, and a tenth resistor R10. The cathode of the third Zener diode VD3 is connected to the first terminal of the second voltage-type switching device Q2, and the anode is connected to the controlled terminal of the second voltage-type switching device Q2. The third Zener diode VD3 is used to protect the second voltage-type switching device Q2, ensuring that the second voltage-type switching device Q2 will not be damaged due to an excessive voltage difference between its first terminal and the controlled terminal. The first terminal of the ninth resistor R9 is connected to the second terminal of the fifth resistor R5, and the second terminal is connected to the first terminal of the switching device 310 and the first terminal of the tenth resistor R10. The ninth resistor R9 is used for current limiting. In addition, the ninth resistor R9 can also be used for circuit debugging. In the event of a large impact when the circuit is powered on or off, the charging and discharging time of the first capacitor C1 can be changed by adjusting the resistance value of the ninth resistor R9, thereby slowly changing the conduction degree of the second voltage-type switching device Q2, and thus reducing the impact. The second end of the tenth resistor R10 is connected to the anode of the third Zener diode VD3 and the controlled terminal of the second voltage-type switching device Q2. The tenth resistor R10 provides a current path for the third Zener diode VD3, ensuring its normal operation and stabilizing the voltage difference between the first and controlled terminals of the second voltage-type switching device Q2. Additionally, both the ninth resistor R9 and the tenth resistor R10 are connected to the switching device 310, allowing the conducting switching device 310 to be used as a current path to output current to ground.

[0120] This utility model also proposes an electronic device, which includes the overvoltage protection circuit. The specific structure of the overvoltage protection circuit is as described in the above embodiments. Since this electronic device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0121] The above description is only an optional embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the inventive concept of the present utility model using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. An overvoltage protection circuit, characterized in that, The overvoltage protection circuit includes: Power supply terminal, output terminal, first voltage-type switching device, and first soft-start circuit; The power supply terminal is used to connect to the power supply voltage; The output terminal is used to connect to the load; The first terminal of the first voltage-type switching device is connected to the power supply terminal, and the second terminal is connected to the output terminal; The input terminal of the first soft-start circuit is connected to the power supply terminal, and the output terminal is connected to the controlled terminal of the first voltage-type switching device. The first voltage-type switching device is used to connect the path between the power supply terminal and the output terminal when the difference between the voltage value at the first terminal and the voltage value at the controlled terminal is greater than a first set threshold. The first soft-start circuit is used to adjust the voltage value at the controlled terminal of the first voltage-type switching device when the power supply voltage is applied to the power supply terminal, so that the difference is greater than a first set threshold after a first time period.

2. The overvoltage protection circuit as described in claim 1, characterized in that, The overvoltage protection circuit further includes: a second voltage-type switching device and a second soft-start circuit; The first terminal of the second voltage-type switching device is connected to the first terminal of the first voltage-type switching device, and the second terminal is connected to the controlled terminal of the first voltage-type switching device; The input terminal of the second soft-start circuit is connected to the power supply terminal, and the output terminal is connected to the controlled terminal of the second voltage-type switching device. The second voltage-type switching device is used to open the path between the first terminal of the first voltage-type switching device and the controlled terminal of the first voltage-type switching device when the difference between the voltage value at the first terminal of the second voltage-type switching device and the voltage value at the controlled terminal of the second voltage-type switching device is greater than a second set threshold. The second soft-start circuit is used to increase the voltage value at the controlled terminal of the second voltage-type switching device when the power supply voltage is applied to the power supply terminal, so that the difference between the voltage value at the first terminal of the second voltage-type switching device and the voltage value at the controlled terminal of the second voltage-type switching device is less than the second set threshold after a second time period; the first time period is greater than the second time period.

3. The overvoltage protection circuit as described in claim 2, characterized in that, The overvoltage protection circuit further includes: a voltage detection and conduction circuit; The first terminal of the voltage detection and conduction circuit is connected to the power supply terminal, the second terminal is grounded, and the output terminal is connected to the controlled terminal of the second voltage-type switching device. The voltage detection circuit is used to open the path between the power supply terminal and ground when the power supply voltage is greater than or equal to a third preset threshold, so as to turn on the second voltage-type switching device and turn off the first voltage-type switching device.

4. The overvoltage protection circuit as described in claim 3, characterized in that, The voltage detection and conduction circuit includes: a switching device and a voltage divider circuit; The first terminal of the switching device is connected to the controlled terminal of the second voltage-type switching device, and the second terminal is grounded; the first terminal of the voltage divider circuit is connected to the power supply terminal, the second terminal is grounded, and the output terminal is connected to the controlled terminal of the switching device. The voltage divider circuit is used to divide the voltage value at the power supply terminal and output it to the controlled terminal of the switching device. The switching device is used to connect the controlled terminal of the second voltage-type switching device to ground when the voltage value at the controlled terminal of the switching device is greater than or equal to the fourth preset threshold.

5. The overvoltage protection circuit as described in claim 4, characterized in that, The voltage divider circuit includes: a resistor voltage divider circuit and a first Zener diode; The cathode of the first Zener diode is connected to the power supply terminal, and the anode is connected to the first terminal of the resistor voltage divider circuit; the second terminal of the resistor voltage divider circuit is grounded, and the output terminal is connected to the controlled terminal of the switching device.

6. The overvoltage protection circuit as described in any one of claims 2 to 5, characterized in that, The first soft-start circuit includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, and a first diode; The first end of the first resistor is connected to the power supply terminal and the first end of the first capacitor, and the second end is connected to the first end of the second resistor, the first end of the third resistor, and the anode of the first diode; the second end of the third resistor is grounded; the second end of the second resistor is connected to the cathode of the first diode, the second end of the first capacitor, and the first end of the fourth resistor; the second end of the fourth resistor is connected to the second end of the second voltage-type switching device.

7. The overvoltage protection circuit as described in claim 6, characterized in that, The second soft-start circuit includes: a fifth resistor, a second capacitor, and a second diode; The fifth resistor and the second diode are connected in parallel; the cathode of the second diode is connected to the power supply terminal, and the anode is connected to the first terminal of the second capacitor and the controlled terminal of the second voltage-type switching device; the second terminal of the second capacitor is grounded.

8. The overvoltage protection circuit as described in claim 7, characterized in that, The time constant of the first RC circuit formed by the fifth resistor and the second capacitor is less than the time constant of the second RC circuit formed by the second resistor, the third resistor and the first capacitor.

9. The overvoltage protection circuit as described in any one of claims 2 to 5, characterized in that, The overvoltage protection circuit also includes: a positive power input terminal, a negative power input terminal, and a reverse connection protection circuit; The reverse connection protection circuit includes: a sixth resistor, a second Zener diode, and an NMOS transistor; The first end of the sixth resistor is connected to the positive input terminal of the power supply and the power supply terminal, and the second end is connected to the gate of the NMOS transistor and the cathode of the second Zener diode; the anode of the second Zener diode is connected to the source of the NMOS transistor and grounded; the drain of the NMOS transistor is connected to the negative input terminal of the power supply.

10. An electronic device, characterized in that, The electronic device includes an overvoltage protection circuit as described in any one of claims 1 to 9.

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