Protection circuit, switching circuit and electric equipment
By adding a protection circuit to the periphery of the driver chip and forming an additional discharge path using the second switch, the problem of the MOSFET being extended after overload detection is solved, and the effect of rapid shutdown and cost reduction is achieved.
Patent Information
- Application Number
- CN202421204523.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-29
- Publication Date
- 2025-02-25
- Estimated Expiration
- 2034-05-29
AI Technical Summary
When protecting MOSFETs, the shutdown time after overload detection is extended, which may lead to damage to the MOSFET, and the method to solve this problem is costly and has high control accuracy.
Design a protection circuit, including a first resistor and a second switch, by adding the protection circuit to the periphery of the drive chip, the second switch is turned on when an overload is detected, forming an additional discharge path, and speeding up the voltage of the control terminal of the MOSFET Descending speed, thereby quickly shutting down the MOSFET.
By adding protection circuits, the shutdown speed of the MOSFET can be accelerated in case of failure, reducing the risk of MOSFET damage, and reducing control costs.
Smart Images
Figure CN222531315U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of power electronics technology, and in particular to a protection circuit, a switch circuit and an electrical device. Background Art
[0002] Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) is a common switching device widely used in various power electronic equipment. MOSFET requires a special driver chip for on-off control.
[0003] During operation, the driver chip samples the MOSFET's electrical parameters such as current and voltage to detect whether the MOSFET's current and power are within the MOSFET's safe operating area (SOA). When it is determined that the detected electrical parameters exceed the SOA, the MOSFET is controlled to be turned off, thereby protecting the safety of the MOSFET and the devices connected to the MOSFET.
[0004] Taking the case where the current of MOSFET exceeds the current value specified by SOA as an example, after MOSFET is turned on, if there is an overload on the line, the driver chip will control the MOSFET to provide drive current, and the voltage Vgs between the gate and drain of MOSFET will slowly drop to the Miller platform voltage, and then the discharge path configured inside the driver chip will drop Vgs to 0V, thereby realizing the shutdown of MOSFET. In this process, although the voltage amplitude at both ends of MOSFET increases due to the drop of Vgs, the MOSFET will not be damaged due to the short shutdown time of MOSFET. However, when the line has been overloaded before MOSFET is turned on, in the process of controlling MOSFET to turn on, the overload on the line is detected through the above sampling process, and the drive current source and discharge current source inside MOSFET are turned on at the same time, resulting in the extension of the shutdown time of MOSFET, and the MOSFET may have been damaged during this time. In order to solve the above problems, generally, only a drive signal with higher cost and more precise control accuracy can be used to meet the overload protection in two different situations, which increases the control cost. Utility Model Content
[0005] The present application provides a protection circuit, a switch circuit and an electrical device for reducing the control cost of a switch device.
[0006] The specific technical solutions provided by the embodiments of this application are as follows:
[0007] In a first aspect, an embodiment of the present application provides a protection circuit, which can be applied to a driver chip and used as a peripheral circuit of the driver chip. The driver chip can be used to drive the on and off of a first switch, which is a voltage-type drive switch.
[0008] The first end of the first resistor is connected to the driving pin of the driving chip, and the second end of the first resistor is connected to the control end of the first switch; the first end of the second switch is connected to the first end of the first switch, and the second end of the second switch is connected to the control end of the first switch, and the control end of the second switch is connected to the first end of the first resistor, and the second switch is used to be turned on when the voltage difference between the control end of the first switch and the first end of the first resistor is greater than a preset threshold. The voltage of the first end of the first switch is less than the voltage of the control end of the first switch.
[0009] With the above design, when the driver chip detects a circuit fault and controls the first switch to be turned off, a discharge path for the voltage at the control end of the first switch will be established inside the driver chip. A reverse current will flow from the control end of the first switch to the driver pin of the driver chip in this discharge path. This reverse current will generate a reverse voltage drop on the first resistor, which will make the second switch meet the conduction condition. The conduction of the second switch constitutes another discharge path for the control end of the first switch. Therefore, the voltage drop speed at the control end of the first switch can be accelerated, thereby accelerating the shutdown speed of the first switch in the event of a fault, thereby ensuring the safety of the first switch.
[0010] In one possible implementation, the second switch may be a current-driven switching device or a voltage-driven switching device. For example, if the second switch is a PNP transistor, the first end of the second switch is the collector of the PNP transistor, the second end of the second switch is the emitter of the PNP transistor, and the control end of the second switch is the base of the PNP transistor.
[0011] In a possible implementation, in order to prevent the current flowing through the second switch from exceeding the maximum current allowed to flow through the second switch when the second switch is turned on, the protection circuit further includes a second resistor, and the second end of the second switch is connected to the control end of the first switch through the second resistor. With the above design, the second resistor can be used as a current limiting resistor of the second switch, and is used to reduce the current amplitude flowing through the second switch when the second switch is turned on, thereby protecting the safety of the second switch.
[0012] In a possible implementation, the protection circuit further includes a third resistor, and the control end of the second switch is connected to the first end of the first resistor through the third resistor. With the above design, the third resistor can be used as a driving resistor of the second switch to control the discharge current of the control end of the second switch.
[0013] In a possible implementation, the protection circuit further includes a diode, the anode of the diode is connected to the control end of the second switch, and the cathode of the diode is connected to the first end of the first resistor. With the above design, when the second switch is turned on, the third resistor passes current and satisfies the conduction condition of the diode. The diode is turned on to clamp the voltage across the third resistor, resulting in a reduction in the impedance of the control end of the second switch, which is conducive to accelerating the current discharge speed.
[0014] In a second aspect, an embodiment of the present application provides a switch circuit, which can be connected between a load and a power supply to control the connection between the power supply and the load. The switch circuit may include at least one first switch and at least one protection circuit provided in the first aspect of the present application and any possible design thereof. Each first switch is connected to each protection circuit in a one-to-one correspondence.
[0015] In a possible implementation, the switch circuit further includes: a driver chip module, and each first switch is connected to the driver chip module via a corresponding protection circuit.
[0016] In a possible implementation, the driver chip module includes a driver chip connected to each protection circuit in a one-to-one correspondence.
[0017] In a possible implementation, the switch circuit further includes a base for mounting the driving chip module.
[0018] In a third aspect, an embodiment of the present application provides an electrical device, which includes a load and a switching circuit provided in the second aspect of the present application and any possible design thereof.
[0019] In addition, the technical effects brought about by the second to third aspects and any possible designs thereof can refer to the technical effects brought about by the different designs in the first aspect of the embodiment of the present application, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.
[0021] Figure 1 A connection diagram of a protection circuit provided in an embodiment of the present application;
[0022] Figure 2 A schematic diagram of a protection circuit provided in an embodiment of the present application Figure 1 ;
[0023] Figure 3 A schematic diagram of the structure of a driver chip provided in an embodiment of the present application;
[0024] Figure 4 A schematic diagram of current flow during a first switch shutdown process provided in an embodiment of the present application;
[0025] Figure 5 A schematic diagram of a waveform of changes in electrical parameters during a first switch-off process provided in an embodiment of the present application;
[0026] Figure 6 A schematic diagram of a protection circuit provided in an embodiment of the present application Figure 2 ;
[0027] Figure 7 A schematic diagram of a protection circuit provided in an embodiment of the present application Figure 3 ;
[0028] Figure 8 A schematic diagram of a protection circuit provided in an embodiment of the present application Figure 4 ;
[0029] Fig. 9 A schematic diagram of the connection between a driver chip and a protection circuit provided in an embodiment of the present application. DETAILED DESCRIPTION
[0030] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.
[0031] The following will introduce the application scenarios of the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. The solution provided in the embodiments of the present application can be applied to power supply scenarios with voltage conversion or control connection requirements. The load can be connected to the power supply through one or more switching devices, and the switching devices can output the voltage output by the power supply to the load directly or after conversion. Among them, the switching devices can be any of various types of switching tubes such as MOSFET, field effect transistor (Field Effect Transistor, FET), insulated gate bipolar transistor (insulated gate bipolar transistor, IGBT), etc.
[0032] In order to facilitate understanding of the technical solution for which protection is sought in the present application, a MOSFET as a switching device is taken as an example for explanation.
[0033] The embodiments of the present application provide a protection circuit, a switch circuit and an electrical device, which are used to protect the safety of a switch device and reduce the control cost of the switch device.
[0034] The technical solution of the present application can be summarized as follows: a protection circuit for quickly shutting down the driven switch device is added to the peripheral circuit of the driver chip, and the protection circuit includes at least one resistor and one switch, and the resistor is connected between the driver chip and the control terminal of the driven switch device. When the driver chip detects that the driven switch device has an overload fault, the driver chip will control the internal discharge path to work, so that a current will be generated on the line from the control terminal of the driven switch device to the driver chip, and the current will generate a voltage drop on the resistor in the protection circuit. This part of the voltage drop will turn on the switch in the protection circuit, and the turned-on switch constitutes a discharge path for the control terminal voltage of the driven switch device, that is, an additional discharge path is added on the basis of the internal discharge path of the driver chip itself, and the simultaneous discharge of the two discharge paths can accelerate the speed of the voltage drop at the control terminal of the driven switch device, thereby realizing the rapid shutdown of the driven switch device and protecting the safety of the driven switch device. In addition, since there is no need to improve the internal structure and control strategy of the driver chip, only a small number of devices need to be added to achieve the above protection function, which is also conducive to reducing the control cost of the driven switch device.
[0035] The connection relationship between the protection circuit provided in the embodiment of the present application and other devices can be found in Figure 1 As shown, Figure 1 As shown, the protection circuit can be used as a peripheral circuit of the driver chip and connected between the driver chip and the driven switch device, which is referred to as the first switch Q1 below. The protection circuit can be fixedly connected to the driver chip and the first switch Q1. The protection circuit can also be connected to the driver chip in a flexible and detachable manner, that is, the protection circuit is fixedly connected to the driven switch device, and a base for mounting the driver chip is provided on the device where the protection circuit is located, and the driver chip is connected to the base in a plug-in connection manner. When the protection circuit is connected to the driver chip, the driver chip can detect the current flowing through the first switch Q1 through the sampling resistor RS, so that the driver chip can monitor the operating status of the first switch Q1 using the detected current.
[0036] It should be noted that the sampling resistor Rs is only a device used by the driver chip to realize current detection. In actual use, other devices with the above functions, such as current sensors, may also be used.
[0037] See also Figure 2As shown in FIG. 1 , a schematic diagram of a protection circuit provided in an embodiment of the present application is shown. Figure 2 As shown, the protection circuit at least includes a first resistor R1 and a second switch Q2.
[0038] Specifically, the first end of the first resistor R1 is connected to the driving pin of the driving chip, the second end of the first resistor R1 is connected to the control end of the first switch Q1; the first end of the second switch Q2 is connected to the first end of the first switch Q1, the second end of the second switch Q2 is connected to the control end of the first switch Q1, and the control end of the second switch Q2 is connected to the first end of the first resistor. The second switch Q2 is used to be turned on when the voltage difference between the control end of the first switch Q1 and the first end of the first resistor R1 is greater than a preset threshold.
[0039] The preset threshold value may be set according to the device type of the second switch. For example, if the second switch is a voltage-type drive switch device, the preset threshold value may be greater than or equal to the turn-on voltage of the second switch.
[0040] It should be noted that the driving pin of the driving chip is the pin for the driving chip to provide a driving electrical signal to the driven switching device. Of course, the driving chip also has other pins, such as an enable signal and a power signal, which will not be introduced in detail in this application.
[0041] Among them, the first end of the first switch Q1 is the port with the lowest voltage amplitude when the first switch Q1 is turned on. When the first switch Q1 is turned on, if the driver chip detects that the first switch Q1 has an overload fault or a short circuit fault, since the voltage at the first end of the first switch Q1 is less than the voltage at the control end of the first switch Q1, after a discharge path is established inside the driver chip, the current will flow from the control end of the first switch Q1 to the first end of the first switch Q1 through the above-mentioned discharge path, and the charge stored in the control end of the first switch Q1 will be consumed, thereby realizing the shutdown of the first switch Q1.
[0042] Using the protection circuit provided in the embodiment of the present application, the second switch Q2 can be a voltage-driven switch or a current-driven switch. Figure 2 As shown, the embodiment of the present application takes the first switch Q1 as an N-type MOSFET and the second switch Q2 as a PNP-type semiconductor transistor (bipolar junction transistor, BJT) as an example to illustrate the working process of the protection circuit. Among them, the control end of the first switch Q1 is the gate of the MOSFET, the first end of the first switch Q1 is the source of the MOSFET, and the second end of the first switch Q1 is the drain of the MOSFET. The control end of the second switch Q2 is the base of the PNP transistor, the first end of the second switch Q2 is the collector of the PNP transistor, and the second end of the second switch Q2 is the emitter of the PNP transistor.
[0043] For practical application, see Figure 3 As shown, generally at least three current sources are set inside the driver chip, and the three current sources are used to provide driving current, overload protection and short circuit protection for the first switch Q1. Taking the current amplitudes of the three current sources as 52uA, 2.2mA and 110mA respectively, during the conduction process of the first switch Q1 and when the first switch Q1 is already in the conduction state, the 52uA current source works and provides a 52uA driving current with a stable amplitude to the control end of the first switch Q1, and the other two current sources stop working. When the driver chip detects through the sampling resistor Rs that the current amplitude actually flowing through the first switch Q1 exceeds the overload current value, the controller inside the driver chip will control the 52uA current source to stop working, and the charge stored in the parasitic capacitor Cgs between the control end G and the first end S of the first switch Q1 will flow to the parasitic capacitor Cgd between the control end G and the second end D, causing the control end voltage Vgs of the first switch Q1 to drop. When the control terminal voltage Vgs of the first switch Q1 drops to the Miller platform voltage, the controller inside the driver chip will control the 2.2mA current source to work, forming a closed path between the control terminal G of the first switch Q1 and the first terminal S of the first switch Q1. The charge stored in the control terminal G of the first switch Q1 will be discharged through the above closed path, and the control terminal voltage Vgs of the first switch Q1 will quickly drop to 0V, thereby controlling the first switch Q1 to be turned off, and realizing overload protection for the first switch Q1 and the first switch Q1 connecting device. Similarly, when the driver chip detects through the sampling resistor Rs that the current amplitude actually flowing through the first switch Q1 exceeds the short-circuit current value, the controller inside the driver chip will control the 52uA current source to stop working. When the control terminal voltage Vgs of the first switch Q1 drops to the Miller platform voltage, the controller inside the driver chip will control the 110mA current source to work, forming a closed path between the control terminal G of the first switch Q1 and the first terminal S of the first switch Q1. The charge stored in the control terminal G of the first switch Q1 will be quickly discharged through the above-mentioned closed path, and the control terminal voltage Vgs of the first switch Q1 will quickly drop to 0V, thereby controlling the first switch Q1 to be turned off, and realizing short-circuit protection of the first switch Q1 and the first switch Q1 connecting device.
[0044] Continue to see Figure 3As shown, if an overload fault has occurred on the line where the first switch Q1 is located before the first switch Q1 is turned on, the driver chip controls the first switch Q1 to be turned on. Since the first switch Q1 is not fully turned on at this time and the driver chip detects an overload fault, the controller inside the driver chip will control the 52uA and 2.2mA current sources to work simultaneously, that is, while the driver chip provides a 52uA driving current for charging the first switch Q1, it will also control the first switch Q1 to discharge with a current of 2.2mA, resulting in a slower discharge speed of the control terminal voltage Vgs of the first switch Q1. If the circuit is not configured with a protection circuit, the first switch Q1 may be damaged due to being in a high-power state for a long time during the off period due to the increase in the off time of the first switch Q1. Using this application Figure 3 In the protection circuit structure shown, since the current output by the 2.2mA current source is greater than the current output by the 52uA current source, the first resistor R1 will pass through the current flowing from the control terminal G of the first switch Q1 to the driving chip, and the current will generate a voltage drop of about 0.7V on the first resistor R1. This part of the voltage drop makes the second switch Q2 meet the conduction condition, and the second switch Q2 is turned on to form a closed path between the control terminal G of the first switch Q1 and the first terminal S of the first switch Q1. Therefore, in addition to a discharge path formed by the 2.2mA current source of the driving chip, the second switch Q2 turned on in the protection circuit will also form a discharge path. The two discharge paths working at the same time can speed up the falling speed of the control terminal voltage Vgs of the first switch Q1, thereby speeding up the turn-off speed of the first switch Q1, and protecting the safety of the first switch Q1 and the first switch Q1 connected components. Similarly, before the first switch Q1 is turned on, a short circuit overload occurs on the line where the first switch Q1 is located. When the driver chip controls the first switch Q1 to be turned on, the controller inside the driver chip will control the 52uA and 110mA current sources to work simultaneously. Since the current output by the 110mA current source is greater than the current output by the 52uA current source, the first switch R1 will pass through the current flowing from the control terminal G of the first switch Q1 to the driver chip. This current will generate a voltage drop on the first resistor R1 to turn on the second switch Q2, and form a closed path between the control terminal G of Q1 and the first terminal S of the first switch Q1, thereby accelerating the turn-off speed of the first switch Q1 and protecting the safety of the first switch Q1 and the devices connected to the first switch Q1.
[0045] When the circuit is overloaded or short-circuited, the discharge path of the control terminal voltage Vgs of the first switch Q1 can be seen in Figure 4 As shown, the waveform diagram of the change of electrical parameters in the circuit can be seen in Figure 5The yellow line is the load current Io, the green line is the voltage Vgs between the control terminal and the first terminal of the first switch Q1, the blue line is the voltage Vds between the second terminal and the first terminal of the first switch Q1, the red line is the power supply voltage, and the pink line is the power loss of the first switch Q1.
[0046] In some embodiments, in order to prevent the current amplitude passing through the second switch Q2 from exceeding the maximum current allowed to pass through the second switch Q2 when the second switch Q2 is turned on, see Figure 6 As shown, the protection circuit provided in the embodiment of the present application may further include a second resistor R2, and the first end of the second switch Q2 is connected to the first end of the first switch Q1 through the second resistor R2. Since the second switch Q2 is a current amplifying switch device, that is, the first end of the second switch Q2
[0047] When the first switch Q1 is overloaded or short-circuited and the second switch Q2 is turned on, the second resistor R2 serves as a current limiting resistor of the second switch Q2 to reduce the current amplitude flowing through the second switch Q2 and protect the safety of the second switch Q2.
[0048] In some embodiments, see Figure 7 As shown, the protection circuit further includes a third resistor R3, and the control end of the second switch Q2 is connected to the first end of the first resistor R1 through the third resistor R3. Figure 7 As shown, the third resistor R3 is connected to the base of the second switch Q2 and serves as a driving resistor for the base of the second switch Q2. The base current of the second switch Q2 is determined by the resistance value of the third resistor R3. Therefore, by configuring a third resistor with a suitable resistance value, the base current value of the second switch Q2 can be adjusted, thereby adjusting the turn-off speed of the first switch Q1.
[0049] In one example, in order to speed up the discharge speed of the voltage at the control terminal of the first switch Q1, see Figure 8 As shown, the protection circuit may further include a diode D1 connected in parallel with the third resistor R3, wherein the anode of the diode D1 is connected to the control end of the second switch Q2, and the cathode of the diode D1 is connected to the first end of the first resistor.
[0050] Combined with the above description, it can be seen that since the additional protection circuit can speed up the turn-off speed of the first switch Q1 when a circuit fault occurs, the driver chip using the above protection circuit can be applied to high-power and high-current working scenarios and meet the circuit safety operation requirements. For example, see Fig. 9 As shown in the figure, it is a connection diagram of the common driver chip in the industry. Fig. 9The driver chip shown uses a plug-in connection method with the driven switching device Q1 as an example. When the driver chip is inserted, the sampling resistor Rs, the resistor R9 and the resistor R7 divide the voltage to provide an enable voltage for the enable pin of the driver chip. The driver chip starts and controls the driven switching device Q1 to turn on. During the conduction process, the driver chip can detect whether the circuit has an overload fault or a short circuit fault through the pin connected to the sampling resistor Rs. When the circuit has an overload fault or a short circuit fault, the protection circuit composed of R1, R2, R3, D1 and Q2 works and achieves the purpose of quickly shutting down Q2.
[0051] In combination with the above description, the embodiment of the present application further provides a switch circuit, which can be connected between a power supply and a load to control the connection between the power supply and the load. The switch circuit may include at least one first switch and at least one protection circuit.
[0052] In some embodiments, if the power output by the power supply can meet the power demand of the load, the switch circuit may include only one first switch, and the first switch is only used to control the connection between the power supply and the load. Figures 2 to 7 shown.
[0053] In some embodiments, if the type of power supply or the voltage amplitude of the power supply output is different from the power demand of the load, the switching circuit includes at least four first switches, and multiple first switches can constitute a conversion circuit, which can not only control the connection between the power supply and the load, but also convert the voltage output by the power supply to meet the power demand of the load.
[0054] In actual use, each first switch is connected to each protection circuit in a one-to-one correspondence. Each protection circuit is used to quickly discharge the control terminal voltage of the first switch when a fault occurs in the connected first switch, thereby quickly shutting down the connected first switch and protecting the safety of the first switch.
[0055] In a possible implementation, the switch circuit further includes a driver chip module, and each first switch is connected to the driver chip module via a corresponding protection circuit. The number of driver chips in the driver chip module can be configured according to the number of first switches in the switch circuit.
[0056] In one example, the driver chip module includes a driver chip connected to each protection circuit in a one-to-one correspondence.
[0057] In another example, only one driver chip may be configured in the driver chip module, and the driver chip may be connected to all the first switches in the switch circuit and control the on and off of all the first switches in the switch circuit.
[0058] In actual use, if the driver chip of the driver chip module is a pluggable chip, the switch circuit also includes a base for mounting the driver chip module. The base is provided with an interface corresponding to the pins of each driver chip in the driver chip module. When the driver chip is inserted into the base, each pin of the driver chip is connected to the corresponding interface.
[0059] In combination with the above description, an embodiment of the present application further provides an electrical device, which may include a load and the aforementioned switch circuit. The switch circuit may be connected between the load and the power supply to control the connection between the load and the power supply. When the power output by the power supply cannot meet the power demand of the load, the switch circuit may also be used to convert the voltage output by the power supply into the supply voltage of the load to ensure that the load operates normally.
[0060] In the various embodiments of the present application, unless otherwise specified or provided for in any logical conflict, the terms and / or descriptions between the different embodiments are consistent and may be referenced to each other, and the technical features in the different embodiments may be combined to form new embodiments according to their inherent logical relationships.
[0061] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the scope of protection of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.
Claims
1. A protection circuit, characterized in that: Applied to a driving chip, the driving chip is used to drive the first switch to be turned on and off, the first switch is a voltage-type driving switch, and the protection circuit includes a first resistor and a second switch; A first end of the first resistor is connected to a driving pin of the driving chip, and a second end of the first resistor is connected to a control end of the first switch; The first end of the second switch is connected to the first end of the first switch, the second end of the second switch is connected to the control end of the first switch, the control end of the second switch is connected to the first end of the first resistor, the second switch is used to be turned on when the voltage difference between the control end of the first switch and the first end of the first resistor is greater than a preset threshold, and the voltage of the first end of the first switch is less than the voltage of the control end of the first switch.
2. The protection circuit according to claim 1, characterized in that: The second switch is a PNP transistor, the first end of the second switch is the collector of the PNP transistor, the second end of the second switch is the emitter of the PNP transistor, and the control end of the second switch is the base of the PNP transistor.
3. The protection circuit according to claim 1 or 2, characterized in that: The protection circuit further includes a second resistor, and the second end of the second switch is connected to the control end of the first switch through the second resistor.
4. The protection circuit according to claim 1 or 2, characterized in that: The protection circuit further includes a third resistor, and the control end of the second switch is connected to the first end of the first resistor through the third resistor.
5. The protection circuit according to claim 4, characterized in that: The protection circuit further includes: a diode, an anode of the diode is connected to the control end of the second switch, and a cathode of the diode is connected to the first end of the first resistor.
6. A switching circuit, characterized in that: include: At least one first switch and at least one protection circuit as claimed in any one of claims 1 to 5, each first switch being connected to each protection circuit in a one-to-one correspondence.
7. The switch circuit according to claim 6, characterized in that: The switch circuit further includes: a driving chip module, and each first switch is connected to the driving chip module via a corresponding protection circuit.
8. The switch circuit according to claim 7, characterized in that: The driving chip module includes a driving chip connected to each protection circuit in a one-to-one correspondence.
9. The switch circuit according to claim 7 or 8, characterized in that: The switch circuit also includes a base for mounting the drive chip module.
10. An electrical device, characterized in that: The invention comprises a load and a switch circuit as claimed in any one of claims 6 to 9.