Failure safety control circuit based on watchdog chip, electrical equipment and method

Abstract

The invention discloses a fault safety control circuit based on a watchdog chip, electrical equipment and a method. The circuit comprises the watchdog chip, a first switching circuit, a charging and discharging circuit and a second switching circuit which are connected in sequence, the watchdog chip is used for outputting a pulse signal when a dog feeding signal sent by the main control chip is not received within a preset time period so as to indicate that the main control chip is in an abnormal operation state; the first switching circuit is used for alternately connecting and disconnecting the power supply end and the charging and discharging circuit in response to the pulse signal, so that the voltage at the two ends of the charging and discharging circuit is smaller than a preset threshold value; the second switching circuit is used for cutting off the connection between the power supply end and the load when the voltage at the two ends of the charging and discharging circuit is smaller than a preset threshold value. The running state of the main control chip is monitored through the watchdog chip, then the load is controlled to work based on the output signal of the watchdog chip, the load can be controlled to be powered off and stop working when the main control chip breaks down, and safe use of electrical equipment is ensured.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a fault-safe control circuit, electrical device, and method based on a watchdog chip. Background Technology

[0002] Many electrical appliances, such as gas water heaters, garbage disposers, and gas boilers, rely on a main control chip (e.g., an MCU chip) to control the on / off state of loads (e.g., gas solenoid valves, grinding motors). However, the safety of the load in these appliances depends entirely on the normal operation of the main control chip. If the main control chip malfunctions and its output becomes abnormal, it may send incorrect drive signals to the load, causing malfunctions and potentially leading to safety accidents. For example, in a gas water heater, the gas valve is directly controlled by the I / O pins of the main control chip. If the main control chip malfunctions and freezes during operation, the gas valve may remain open, causing continuous gas leakage and posing a significant risk of fire and explosion. Therefore, the market urgently needs a fail-safe control circuit to ensure that the load can be autonomously and reliably driven to the off state when the main control chip fails. Summary of the Invention

[0003] This invention provides a fault-safe control circuit, electrical equipment, and method based on a watchdog chip, aiming to solve the problem of load malfunction caused by a main control chip failure in the prior art.

[0004] In a first aspect, embodiments of the present invention provide a fault-safe control circuit based on a watchdog chip, applied to an electrical device body. The electrical device body includes a main control chip, a load, and a power supply terminal. The fault-safe control circuit based on the watchdog chip includes a watchdog chip, a first switching circuit, a charging / discharging circuit, and a second switching circuit connected in sequence. The watchdog chip is also connected to the main control chip, the first switching circuit is also connected to the power supply terminal, and the second switching circuit is also connected to the load and the power supply terminal. The watchdog chip outputs a pulse signal when it does not receive a "feed" signal from the main control chip within a preset time period, indicating that the main control chip is in an abnormal operating state. The first switching circuit, in response to the pulse signal, alternately connects and disconnects the connection between the power supply terminal and the charging / discharging circuit, such that the voltage across the charging / discharging circuit is less than a preset threshold. The second switching circuit disconnects the connection between the power supply terminal and the load when the voltage across the charging / discharging circuit is less than the preset threshold.

[0005] Furthermore, the first switching circuit includes a first switching device and a second switching device; the first switching device is connected to the watchdog chip and the second switching device, and the second switching device is connected to the power supply terminal and the charging and discharging circuit.

[0006] Furthermore, the first switching circuit also includes a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor; the first terminal of the first switching device is connected to the watchdog chip through the first resistor, the second terminal of the first switching device is connected to the first terminal of the second switching device through the second resistor, the second terminal of the second switching device is connected to the charging and discharging circuit through the third resistor, the first terminal of the fourth resistor is connected to the first terminal of the first switching device, the second terminal of the fourth resistor and the third terminal of the first switching device are both grounded, the first terminal of the fifth resistor and the third terminal of the second switching device are both connected to the power supply terminal, and the second terminal of the fifth resistor is connected to the first terminal of the second switching device.

[0007] Furthermore, the charging and discharging circuit includes a first capacitor and a sixth resistor; the first terminal of the first capacitor is connected to the first switching circuit and the second switching circuit, the second terminal of the first capacitor is grounded, and the two terminals of the sixth resistor are respectively connected to the two terminals of the first capacitor.

[0008] Furthermore, the second switching circuit includes a Zener diode, a third switching device, and a fourth switching device; the cathode of the Zener diode is connected to the charging and discharging circuit, the anode of the Zener diode is connected to the third switching device, the third switching device is connected to the fourth switching device, and the fourth switching device is connected to the load and the power supply terminal.

[0009] Furthermore, the second switching circuit also includes a seventh resistor, an eighth resistor, a ninth resistor, and a tenth resistor; the anode of the Zener diode is connected to the first terminal of the third switching device through the seventh resistor, the second terminal of the third switching device is connected to the first terminal of the fourth switching device through the ninth resistor, the first terminal of the eighth resistor is connected to the first terminal of the third switching device, and the second terminal of the eighth resistor and the third terminal of the third switching device are both grounded; the second terminal of the fourth switching device is connected to the load, the third terminal of the fourth switching device and the first terminal of the tenth resistor are both connected to the power supply terminal, and the second terminal of the tenth resistor is connected to the first terminal of the fourth switching device.

[0010] Furthermore, the second switching circuit also includes a freewheeling diode; the cathode of the freewheeling diode is connected to the node where the fourth switching device and the load are connected, and the anode of the freewheeling diode is grounded.

[0011] Secondly, embodiments of the present invention also provide an electrical device, comprising: an electrical device body and a fault-safe control circuit based on a watchdog chip as described in the first aspect. The electrical device body includes a main control chip, a load, and a power supply terminal. The fault-safe control circuit based on a watchdog chip includes a watchdog chip, a first switching circuit, a charging / discharging circuit, and a second switching circuit connected in sequence. The watchdog chip is also connected to the main control chip, the first switching circuit is also connected to the power supply terminal, and the second switching circuit is also connected to the load and the power supply terminal.

[0012] Thirdly, embodiments of the present invention also provide a fail-safe control method, applied to the electrical equipment as described in the second aspect, comprising: When the watchdog chip does not receive a "feed the watchdog" signal from the main control chip within a preset time period, it outputs a pulse signal to indicate that the main control chip is in an abnormal operating state. In response to the pulse signal, the first switching circuit alternately connects and disconnects the connection between the power supply terminal and the charging and discharging circuit, so that the voltage across the charging and discharging circuit is less than a preset threshold. When the voltage across the charging / discharging circuit is less than the preset threshold, the second switching circuit disconnects the connection between the power supply terminal and the load.

[0013] Furthermore, the fail-safe control method further includes: When the watchdog chip receives a "feed the watchdog" signal from the main control chip within the preset time period, it outputs a high-level signal to indicate that the main control chip is in normal operating condition. In response to the high-level signal, the first switching circuit connects the power supply terminal and the charging / discharging circuit to enable the charging / discharging circuit to charge continuously. When the voltage across the charging / discharging circuit is greater than the preset threshold, the second switching circuit connects the power supply terminal to the load.

[0014] This invention provides a fault-safe control circuit, electrical device, and method based on a watchdog chip. The circuit includes a watchdog chip, a first switching circuit, a charging / discharging circuit, and a second switching circuit connected in sequence. The watchdog chip is also connected to a main control chip. The first switching circuit is also connected to a power supply terminal and the charging / discharging circuit. The second switching circuit is also connected to a load and the power supply terminal. The watchdog chip outputs a pulse signal when it does not receive a "feed" signal from the main control chip within a preset time period, indicating that the main control chip is in an abnormal operating state. The first switching circuit, in response to the pulse signal, alternately connects and disconnects the connection between the power supply terminal and the charging / discharging circuit, causing the voltage across the charging / discharging circuit to be less than a preset threshold. The second switching circuit disconnects the connection between the power supply terminal and the load when the voltage across the charging / discharging circuit is less than the preset threshold. This invention monitors the operating status of the main control chip using a watchdog chip, and then controls the operation of the load based on the output signal of the watchdog chip. It can control the load to stop working when the main control chip fails, ensuring the safe use of the electrical device. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic block diagram of a watchdog chip-based fault-safe control circuit provided in an embodiment of the present invention. Figure 2 A schematic block diagram showing the connection between a watchdog chip-based fault-safe control circuit and the electrical equipment body, according to an embodiment of the present invention. Figure 3 A circuit diagram of a watchdog chip-based fault-safe control circuit provided in an embodiment of the present invention; Figure 4 This is a flowchart illustrating a fault-tolerant control method according to an embodiment of the present invention. Figure 5 This is a flowchart illustrating a fail-safe control method provided in another embodiment of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0019] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0020] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0021] In the embodiments of the present invention, any resistor or capacitor mentioned is arranged horizontally in the circuit diagram, and from left to right, they are the first end of the resistor or capacitor and the second end of the resistor or capacitor; if the resistor or capacitor is arranged perpendicular to the horizontal direction in the circuit diagram, from top to bottom, they are the first end of the resistor or capacitor and the second end of the resistor or capacitor.

[0022] Please see Figures 1 to 3 , Figure 1 This is a schematic block diagram of a watchdog chip-based fault-safe control circuit provided in an embodiment of the present invention. Figure 2 A schematic block diagram showing the connection between a watchdog chip-based fault-safe control circuit and the electrical equipment body, according to an embodiment of the present invention. Figure 3 The circuit diagram shows a fault-safe control circuit based on a watchdog chip provided in an embodiment of the present invention.

[0023] This invention provides a fault-safe control circuit based on a watchdog chip, applied to an electrical device body. The electrical device body includes a main control chip 21, a load 22, and a power supply terminal 23. The circuit includes a watchdog chip 11, a first switching circuit 12, a charging / discharging circuit 13, and a second switching circuit 14 connected in sequence. The watchdog chip 11 is also connected to the main control chip 21, the first switching circuit 12 is also connected to the power supply terminal 23, and the second switching circuit 14 is also connected to the load 22 and the power supply terminal 23.

[0024] The watchdog chip 11 is used to output a pulse signal when it does not receive a "feed the dog" signal from the main control chip 21 within a preset time period, to indicate that the main control chip 21 is in an abnormal operating state; the first switching circuit 12 is used to respond to the pulse signal to alternately connect and disconnect the connection between the power supply terminal 23 and the charging and discharging circuit 13, so that the voltage across the charging and discharging circuit 13 is less than a preset threshold; the second switching circuit 14 is used to disconnect the connection between the power supply terminal 23 and the load 22 when the voltage across the charging and discharging circuit 13 is less than the preset threshold.

[0025] In this embodiment, refer to Figure 1 and Figure 2 The watchdog chip-based fault-safe control circuit provided in this embodiment consists of a watchdog chip 11, a first switching circuit 12, a charging / discharging circuit 13, and a second switching circuit 14. The watchdog chip 11 is connected to the first switching circuit 12, one end of the charging / discharging circuit 13 is connected to the first switching circuit 12, and the other end of the charging / discharging circuit 13 is connected to the second switching circuit 14. In specific applications, this fault-safe control circuit is applied to the electrical equipment body, which refers to a device that controls the operation of the load 22 through the main control chip 21, such as a gas water heater, garbage disposer, or gas wall-hung boiler. The electrical equipment body includes the main control chip 21, the load 22, and the power supply terminal 23. The watchdog chip 11 is connected to the main control chip 21, the first switching circuit 12 is connected to the power supply terminal 23, and the second switching circuit 14 is connected to both the load 22 and the power supply terminal 23.

[0026] The main control chip 21 sends a periodic "feed" signal to the watchdog chip 11 during normal operation and stops sending the "feed" signal during abnormal operation. The watchdog chip 11 determines the operating status of the main control chip 21 by monitoring whether the main control chip 21 sends a "feed" signal within a preset time period, and outputs different signals according to the operating status of the main control chip 21. Under the action of the output signal of the watchdog chip 11, the first switching circuit 12, the charging and discharging circuit 13, and the second switching circuit 14 control the on / off of the load 22, so that when the main control chip 21 fails, the load 22 can be powered off and stop working, ensuring the safe use of electrical equipment.

[0027] Specifically, if the watchdog chip 11 does not receive a "feed" signal from the main control chip 21 within a preset time period, the watchdog chip 11 determines that the main control chip 21 is in an abnormal operating state, i.e., the main control chip 21 has malfunctioned, and the watchdog chip 11 outputs a pulse signal. Then, the first switching circuit 12 responds to the pulse signal output by the watchdog chip 11, turning on during the high level of the pulse signal and turning off during the low level of the pulse signal. That is, the first switching circuit 12 periodically turns on and off according to the pulse signal, thereby alternately connecting and disconnecting the connection between the power supply terminal 23 and the charging and discharging circuit 13. When the first switch circuit 12 is turned on, the connection between the charging / discharging circuit 13 and the power supply terminal 23 is established, and the power supply terminal 23 charges the charging / discharging circuit 13. When the first switch circuit 12 is turned off, the connection between the charging / discharging circuit 13 and the power supply terminal 23 is severed, and the charging / discharging circuit 13 discharges. During the alternating charging and discharging process, the charging time is too short, causing all the stored energy to be released, resulting in the voltage across its terminals being lower than a preset threshold. Finally, since the on / off state of the second switch circuit 14 is controlled by the voltage across the charging / discharging circuit 13, when the voltage across the charging / discharging circuit 13 is lower than the preset threshold due to alternating charging and discharging, the second switch circuit 14 is turned off, thereby cutting off the connection between the power supply terminal 23 and the load 22. This ensures that the load 22 is powered off and stops working when the main control chip 21 fails, thus ensuring the safe use of the electrical equipment.

[0028] Furthermore, the watchdog chip 11 is also used to output a high-level signal when it receives a "feed the watchdog" signal sent by the main control chip 21 within the preset time period, so as to indicate that the main control chip 21 is in normal operation; the first switching circuit 12 is also used to connect the power supply terminal 23 and the charging and discharging circuit 13 in response to the high-level signal, so as to make the charging and discharging circuit 13 continuously charge; the second switching circuit 14 is also used to connect the power supply terminal 23 and the load 22 when the voltage across the charging and discharging circuit 13 is greater than the preset threshold.

[0029] In this embodiment, when the watchdog chip 11 receives a "feed" signal from the main control chip 21 within a preset time period, the watchdog chip 11 determines that the main control chip 21 is in normal operating condition, i.e., the main control chip 21 is operating normally without malfunction, and the watchdog chip 11 outputs a high-level signal. Then, the first switching circuit 12 is turned on in response to the high-level signal output by the watchdog chip 11, thereby continuously connecting the power supply terminal 23 and the charging / discharging circuit 13. At this time, the power supply terminal 23 continuously charges the charging / discharging circuit 13. Finally, when the voltage across the charging / discharging circuit 13 exceeds a preset threshold due to continuous charging, the second switching circuit 14 is turned on, thereby connecting the power supply terminal 23 and the load 22, allowing the load 22 to be powered on and operate normally.

[0030] In a more specific embodiment, the first switching circuit 12 includes a first switching device Q1 and a second switching device Q2; the first switching device Q1 is connected to the watchdog chip 11 and the second switching device Q2, and the second switching device Q2 is connected to the power supply terminal 23 and the charging and discharging circuit 13.

[0031] In this embodiment, refer to Figure 3 The first switching device Q1 is connected to the output terminal of the watchdog chip 11. When the watchdog chip 11 detects that the main control chip 21 is in an abnormal operating state and outputs a pulse signal, the first switching device Q1 periodically turns on and off according to the pulse signal, causing the second switching device Q2 to also periodically turn on and off, thereby alternately connecting and disconnecting the connection between the power supply terminal 23 and the charging / discharging circuit 13 through the second switching device Q2. When the watchdog chip 11 detects that the main control chip 21 is in a normal operating state and outputs a high-level signal, the first switching device Q1 turns on according to the high-level signal, thereby causing the second switching device Q2 to turn on, thereby connecting the connection between the power supply terminal 23 and the charging / discharging circuit 13 through the second switching device Q2.

[0032] In specific applications, the first switching device Q1 and the second switching device Q2 can be transistors or MOSFETs. For example... Figure 3 As shown, the first switching device Q1 can be an NPN transistor, and the second switching device Q2 can be a PNP transistor. Alternatively, the first switching device Q1 can also be an NMOS transistor, and the second switching device Q2 can also be a PMOS transistor; no specific limitation is made here.

[0033] In a more specific embodiment, the first switching circuit 12 further includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5; the first terminal of the first switching device Q1 is connected to the watchdog chip 11 through the first resistor R1, the second terminal of the first switching device Q1 is connected to the first terminal of the second switching device Q2 through the second resistor R2, the second terminal of the second switching device Q2 is connected to the charging and discharging circuit 13 through the third resistor R3, the first terminal of the fourth resistor R4 is connected to the first terminal of the first switching device Q1, the second terminal of the fourth resistor R4 and the third terminal of the first switching device Q1 are both grounded, the first terminal of the fifth resistor R5 and the third terminal of the second switching device Q2 are both connected to the power supply terminal 23, and the second terminal of the fifth resistor R5 is connected to the first terminal of the second switching device Q2.

[0034] In this embodiment, refer to Figure 3 The first resistor R1, the second resistor R2, and the third resistor R3 serve as current-limiting resistors to prevent excessive current from burning out the components connected in series. The fourth resistor R4 serves as a pull-down resistor, and the fifth resistor R5 serves as a pull-up resistor, ensuring that the first terminals (i.e., control terminals) of the first switching device Q1 and the second switching device Q2 will not be mis-turned on even if they are disturbed, without receiving a control signal.

[0035] In a more specific embodiment, the charging and discharging circuit 13 includes a first capacitor C1 and a sixth resistor R6; the first end of the first capacitor C1 is connected to the first switching circuit 12 and the second switching circuit 14, the second end of the first capacitor C1 is grounded, and the two ends of the sixth resistor R6 are respectively connected to the two ends of the first capacitor C1.

[0036] In this embodiment, refer to Figure 3 When the first switching circuit 12 is turned on, the connection between the first terminal of the first capacitor C1 and the power supply terminal 23 is established, and the power supply from the power supply terminal 23 charges the first capacitor C1. When the first switching circuit 12 is turned off, the connection between the first terminal of the first capacitor C1 and the power supply terminal 23 is broken. At this time, the first capacitor C1 and the sixth resistor R6 form a circuit, and the first capacitor C1 discharges, allowing the voltage across the first capacitor C1 to change through charging and discharging.

[0037] In a more specific embodiment, the second switching circuit 14 includes a Zener diode D1, a third switching device Q3, and a fourth switching device Q4; the cathode of the Zener diode D1 is connected to the charging and discharging circuit 13, the anode of the Zener diode D1 is connected to the third switching device Q3, the third switching device Q3 is connected to the fourth switching device Q4, and the fourth switching device Q4 is connected to the load 22 and the power supply terminal 23.

[0038] In this embodiment, refer to Figure 3 When the voltage across the charging / discharging circuit 13 is lower than a preset threshold due to alternating charging and discharging (the preset threshold being the voltage regulation threshold of the Zener diode D1), the Zener diode D1 cannot conduct. Both the third switch Q3 and the fourth switch Q4 are turned off, thus disconnecting the connection between the power supply terminal 23 and the load 22 via the fourth switch Q4, causing the load 22 to stop working. When the voltage across the charging / discharging circuit 13 exceeds the preset threshold due to continuous charging, the Zener diode D1 conducts, and both the third switch Q3 and the fourth switch Q4 conduct. This connects the power supply terminal 23 to the load 22 via the fourth switch Q4, allowing the load 22 to operate normally.

[0039] In specific applications, the third switching device Q3 and the fourth switching device Q4 can be transistors or MOSFETs. For example... Figure 3 As shown, the third switching device Q3 can be an NPN transistor, and the fourth switching device Q4 can be a PNP transistor. Alternatively, the third switching device Q3 can also be an NMOS transistor, and the fourth switching device Q4 can also be a PMOS transistor; no specific limitation is made here.

[0040] In a more specific embodiment, the second switching circuit 14 further includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10; the anode of the Zener diode is connected to the first terminal of the third switching device through the seventh resistor R7, the second terminal of the third switching device is connected to the first terminal of the fourth switching device through the ninth resistor R9, the first terminal of the eighth resistor R8 is connected to the first terminal of the third switching device, and the second terminal of the eighth resistor R8 and the third terminal of the third switching device are both grounded; the second terminal of the fourth switching device is connected to the load 22, the third terminal of the fourth switching device and the first terminal of the tenth resistor R10 are both connected to the power supply terminal 23, and the second terminal of the tenth resistor R10 is connected to the first terminal of the fourth switching device.

[0041] In this embodiment, refer to Figure 3 The seventh resistor R7 and the ninth resistor R9 act as current-limiting resistors to prevent excessive current from burning out the components connected in series. The eighth resistor R8 acts as a pull-down resistor, and the tenth resistor R10 acts as a pull-up resistor, ensuring that the first terminals (i.e., control terminals) of the third switching device Q3 and the fourth switching device Q4 will not be mis-turned on even if they are disturbed, without receiving a control signal.

[0042] In a more specific embodiment, the second switching circuit 14 further includes a freewheeling diode D2; the cathode of the freewheeling diode D2 is connected to the node where the fourth switching device Q4 and the load 22 are connected, and the anode of the freewheeling diode D2 is grounded.

[0043] In this embodiment, the freewheeling diode D2 is connected in parallel with the load 22. The load 22 of some electrical devices is an inductive load. The parallel connection of the freewheeling diode D2 provides a low-impedance path for the current in the inductor when the inductive load 22 is de-energized, preventing high voltage from damaging the circuit. Alternatively, if the load 22 to be controlled is a non-inductive load 22, the freewheeling diode D2 can be omitted.

[0044] For ease of understanding, such as Figure 3 As shown, the fault-tolerant control circuit based on the watchdog chip includes a watchdog chip 11, a first switching circuit 12, a charging / discharging circuit 13, and a second switching circuit 14 connected in sequence. The first switching circuit 12 includes a first switching device Q1, a second switching device Q2, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5. The charging / discharging circuit 13 includes a first capacitor C1 and a sixth resistor R6. The second switching circuit 14 includes a Zener diode D1, a third switching device Q3, a fourth switching device Q4, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10. Now, regarding... Figure 3 The working process of the watchdog-based fault-safe control circuit is described below: The watchdog chip 11 monitors whether the main control chip 21 sends a feeding signal within a preset time period. When the watchdog chip 11 detects that the main control chip 21 does not send a feeding signal within the preset time period, the watchdog chip 11 determines that the main control chip 21 is in an abnormal operating state, that is, the main control chip 21 has failed, and the watchdog chip 11 outputs a pulse signal. When the first terminal of the first switching device Q1 receives a pulse signal, during the high-level period of the pulse signal, the second and third terminals of the first switching device Q1 are turned on, causing the first terminal of the second switching device Q2 to be in a low-level state. This causes the second and third terminals of the second switching device Q2 to be turned on, thereby connecting the power supply terminal 23 and the first capacitor C1 through the second switching device Q2, and the power supply of the power supply terminal 23 charges the first capacitor C1. During the low-level period of the pulse signal, the second and third terminals of the first switching device Q1 are turned off, causing the first terminal of the second switching device Q2 to be in a high-level state. This causes the second and third terminals of the second switching device Q2 to be turned off, thereby disconnecting the power supply terminal 23 and the first capacitor C1 through the second switching device Q2. The first capacitor C1 and the sixth resistor R6 then form a circuit, and the first capacitor C1 discharges. During the alternating charging and discharging process, the first capacitor C1 releases all its stored energy due to the short charging time, causing the voltage across it to fall below a preset threshold. At this point, the Zener diode D1 cannot conduct, resulting in the first terminal of the third switching device Q3 being at a low level and the second and third terminals of Q3 being turned off. Consequently, the first terminal of the fourth switching device Q4 is at a high level, and the second and third terminals of Q4 are turned off. Thus, the connection between the power supply terminal 23 and the load 22 is cut off through the fourth switching device Q4, causing the load 22 to stop working.

[0045] When the watchdog chip 11 detects that the main control chip 21 sends a "feed" signal within a preset time period, the watchdog chip 11 determines that the main control chip 21 is in normal operating condition, and outputs a high-level signal. The first terminal of the first switching device Q1 receives the high-level signal, at which point the second and third terminals of the first switching device Q1 are turned on, causing the first terminal of the second switching device Q2 to be in a low-level state. This, in turn, causes the second and third terminals of the second switching device Q2 to be turned on, thereby connecting the power supply terminal 23 and the first capacitor C1 through the second switching device Q2. The power supply from the power supply terminal 23 charges the first capacitor C1. When the voltage across the first capacitor C1 exceeds a preset threshold due to continuous charging, the Zener diode D1 conducts, causing the first terminal of the third switching device Q3 to be in a high-level state. The second and third terminals of the third switching device Q3 are also conducted, which in turn causes the first terminal of the fourth switching device Q4 to be in a low-level state. The second and third terminals of the fourth switching device Q4 are also conducted, thereby connecting the power supply terminal 23 and the load 22 through the fourth switching device Q4, enabling the load 22 to be powered on and operate normally.

[0046] The fault safety control circuit based on the watchdog chip in this embodiment of the invention monitors the operating status of the main control chip 21 through the watchdog chip 11, and then controls the operation of the load 22 based on the output signal of the watchdog chip 11. It can control the load 22 to cut off power and stop working when the main control chip 21 fails, thus ensuring the safe use of electrical equipment.

[0047] Please see Figure 2 This invention also provides an electrical device, including an electrical device body and a watchdog chip-based fault-safe control circuit as described in the foregoing embodiments. The electrical device body includes a main control chip 21, a load 22, and a power supply terminal 23. The watchdog chip-based fault-safe control circuit includes a watchdog chip 11, a first switching circuit 12, a charging / discharging circuit 13, and a second switching circuit 14 connected in sequence. The watchdog chip 11 is also connected to the main control chip 21, the first switching circuit 12 is also connected to the power supply terminal 23, and the second switching circuit 14 is also connected to the load 22 and the power supply terminal 23.

[0048] The main control chip 21 is used to send a periodic "feed" signal to the watchdog chip 11 during normal operation; the main control chip 21 is also used to stop sending the "feed" signal to the watchdog chip 11 during abnormal operation; the watchdog chip 11 is used to output a pulse signal when it does not receive the "feed" signal from the main control chip 21 within a preset time period to indicate that the main control chip 21 is in an abnormal operating state; the first switching circuit 12 is used to respond to the pulse signal to alternately connect and disconnect the connection between the power supply terminal 23 and the charging and discharging circuit 13, so that the voltage across the charging and discharging circuit 13 is less than a preset threshold; the second switching circuit 14 is used to disconnect the connection between the power supply terminal 23 and the load 22 when the voltage across the charging and discharging circuit 13 is less than the preset threshold.

[0049] In this embodiment, refer to Figure 2The electrical equipment provided in this embodiment refers to a complete machine having an electrical equipment body and a fault-safe control circuit based on a watchdog chip provided in the aforementioned embodiment. The fault-safe control circuit based on the watchdog chip consists of a watchdog chip 11, a first switching circuit 12, a charging / discharging circuit 13, and a second switching circuit 14. The watchdog chip 11 is connected to the first switching circuit 12, one end of the charging / discharging circuit 13 is connected to the first switching circuit 12, and the other end of the charging / discharging circuit 13 is connected to the second switching circuit 14. The electrical equipment body refers to a device that controls the operation of the load 22 through a main control chip 21, such as a gas water heater, a garbage disposer, or a gas wall-hung boiler. The electrical equipment body includes a main control chip 21, a load 22, and a power supply terminal 23. The watchdog chip 11 is connected to the main control chip 21, the first switching circuit 12 is connected to the power supply terminal 23, and the second switching circuit 14 is connected to both the load 22 and the power supply terminal 23.

[0050] The main control chip 21 sends a periodic "feed" signal to the watchdog chip 11 during normal operation and stops sending the "feed" signal during abnormal operation. The watchdog chip 11 determines the operating status of the main control chip 21 by monitoring whether the main control chip 21 sends a "feed" signal within a preset time period, and outputs different signals according to the operating status of the main control chip 21. Under the action of the output signal of the watchdog chip 11, the first switching circuit 12, the charging and discharging circuit 13, and the second switching circuit 14 control the on / off of the load 22, so that when the main control chip 21 fails, the load 22 can be powered off and stop working, ensuring the safe use of electrical equipment.

[0051] Specifically, if the watchdog chip 11 does not receive a "feed" signal from the main control chip 21 within a preset time period, the watchdog chip 11 determines that the main control chip 21 is in an abnormal operating state, i.e., the main control chip 21 has malfunctioned, and the watchdog chip 11 outputs a pulse signal. Then, the first switching circuit 12 responds to the pulse signal output by the watchdog chip 11, turning on during the high level of the pulse signal and turning off during the low level of the pulse signal. That is, the first switching circuit 12 periodically turns on and off according to the pulse signal, thereby alternately connecting and disconnecting the connection between the power supply terminal 23 and the charging and discharging circuit 13. When the first switch circuit 12 is turned on, the connection between the charging / discharging circuit 13 and the power supply terminal 23 is established, and the power supply terminal 23 charges the charging / discharging circuit 13. When the first switch circuit 12 is turned off, the connection between the charging / discharging circuit 13 and the power supply terminal 23 is severed, and the charging / discharging circuit 13 discharges. During the alternating charging and discharging process, the charging time is too short, causing all the stored energy to be released, resulting in the voltage across its terminals being lower than a preset threshold. Finally, since the on / off state of the second switch circuit 14 is controlled by the voltage across the charging / discharging circuit 13, when the voltage across the charging / discharging circuit 13 is lower than the preset threshold due to alternating charging and discharging, the second switch circuit 14 is turned off, thereby cutting off the connection between the power supply terminal 23 and the load 22. This ensures that the load 22 is powered off and stops working when the main control chip 21 fails, thus ensuring the safe use of the electrical equipment.

[0052] Furthermore, the watchdog chip 11 is also used to output a high-level signal when it receives a "feed the watchdog" signal sent by the main control chip 21 within the preset time period, so as to indicate that the main control chip 21 is in normal operation; the first switching circuit 12 is also used to connect the power supply terminal 23 and the charging and discharging circuit 13 in response to the high-level signal, so as to make the charging and discharging circuit 13 continuously charge; the second switching circuit 14 is also used to connect the power supply terminal 23 and the load 22 when the voltage across the charging and discharging circuit 13 is greater than the preset threshold.

[0053] In this embodiment, when the watchdog chip 11 receives a "feed" signal from the main control chip 21 within a preset time period, the watchdog chip 11 determines that the main control chip 21 is in normal operating condition, i.e., the main control chip 21 is operating normally without malfunction, and the watchdog chip 11 outputs a high-level signal. Then, the first switching circuit 12 is turned on in response to the high-level signal output by the watchdog chip 11, thereby continuously connecting the power supply terminal 23 and the charging / discharging circuit 13. At this time, the power supply terminal 23 continuously charges the charging / discharging circuit 13. Finally, when the voltage across the charging / discharging circuit 13 exceeds a preset threshold due to continuous charging, the second switching circuit 14 is turned on, thereby connecting the power supply terminal 23 and the load 22, allowing the load 22 to be powered on and operate normally.

[0054] In a more specific embodiment, the first switching circuit 12 includes a first switching device Q1 and a second switching device Q2; the first switching device Q1 is connected to the watchdog chip 11 and the second switching device Q2, and the second switching device Q2 is connected to the power supply terminal 23 and the charging and discharging circuit 13.

[0055] In this embodiment, refer to Figure 3 The first switching device Q1 is connected to the output terminal of the watchdog chip 11. When the watchdog chip 11 detects that the main control chip 21 is in an abnormal operating state and outputs a pulse signal, the first switching device Q1 periodically turns on and off according to the pulse signal, causing the second switching device Q2 to also periodically turn on and off, thereby alternately connecting and disconnecting the connection between the power supply terminal 23 and the charging / discharging circuit 13 through the second switching device Q2. When the watchdog chip 11 detects that the main control chip 21 is in a normal operating state and outputs a high-level signal, the first switching device Q1 turns on according to the high-level signal, thereby causing the second switching device Q2 to turn on, thereby connecting the connection between the power supply terminal 23 and the charging / discharging circuit 13 through the second switching device Q2.

[0056] In specific applications, the first switching device Q1 and the second switching device Q2 can be transistors or MOSFETs. For example... Figure 3 As shown, the first switching device Q1 can be an NPN transistor, and the second switching device Q2 can be a PNP transistor. Alternatively, the first switching device Q1 can also be an NMOS transistor, and the second switching device Q2 can also be a PMOS transistor; no specific limitation is made here.

[0057] In a more specific embodiment, the first switching circuit 12 further includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5; the first terminal of the first switching device Q1 is connected to the watchdog chip 11 through the first resistor R1, the second terminal of the first switching device Q1 is connected to the first terminal of the second switching device Q2 through the second resistor R2, the second terminal of the second switching device Q2 is connected to the charging and discharging circuit 13 through the third resistor R3, the first terminal of the fourth resistor R4 is connected to the first terminal of the first switching device Q1, the second terminal of the fourth resistor R4 and the third terminal of the first switching device Q1 are both grounded, the first terminal of the fifth resistor R5 and the third terminal of the second switching device Q2 are both connected to the power supply terminal 23, and the second terminal of the fifth resistor R5 is connected to the first terminal of the second switching device Q2.

[0058] In this embodiment, refer to Figure 3 The first resistor R1, the second resistor R2, and the third resistor R3 serve as current-limiting resistors to prevent excessive current from burning out the components connected in series. The fourth resistor R4 serves as a pull-down resistor, and the fifth resistor R5 serves as a pull-up resistor, ensuring that the first terminals (i.e., control terminals) of the first switching device Q1 and the second switching device Q2 will not be mis-turned on even if they are disturbed, without receiving a control signal.

[0059] In a more specific embodiment, the charging and discharging circuit 13 includes a first capacitor C1 and a sixth resistor R6; the first end of the first capacitor C1 is connected to the first switching circuit 12 and the second switching circuit 14, the second end of the first capacitor C1 is grounded, and the two ends of the sixth resistor R6 are respectively connected to the two ends of the first capacitor C1.

[0060] In this embodiment, refer to Figure 3 When the first switching circuit 12 is turned on, the connection between the first terminal of the first capacitor C1 and the power supply terminal 23 is established, and the power supply from the power supply terminal 23 charges the first capacitor C1. When the first switching circuit 12 is turned off, the connection between the first terminal of the first capacitor C1 and the power supply terminal 23 is broken. At this time, the first capacitor C1 and the sixth resistor R6 form a circuit, and the first capacitor C1 discharges, allowing the voltage across the first capacitor C1 to change through charging and discharging.

[0061] In a more specific embodiment, the second switching circuit 14 includes a Zener diode D1, a third switching device Q3, and a fourth switching device Q4; the cathode of the Zener diode D1 is connected to the charging and discharging circuit 13, the anode of the Zener diode D1 is connected to the third switching device Q3, the third switching device Q3 is connected to the fourth switching device Q4, and the fourth switching device Q4 is connected to the load 22 and the power supply terminal 23.

[0062] In this embodiment, refer to Figure 3 When the voltage across the charging / discharging circuit 13 is lower than a preset threshold due to alternating charging and discharging (the preset threshold being the voltage regulation threshold of the Zener diode D1), the Zener diode D1 cannot conduct. Both the third switch Q3 and the fourth switch Q4 are turned off, thus disconnecting the connection between the power supply terminal 23 and the load 22 via the fourth switch Q4, causing the load 22 to stop working. When the voltage across the charging / discharging circuit 13 exceeds the preset threshold due to continuous charging, the Zener diode D1 conducts, and both the third switch Q3 and the fourth switch Q4 conduct. This connects the power supply terminal 23 to the load 22 via the fourth switch Q4, allowing the load 22 to operate normally.

[0063] In specific applications, the third switching device Q3 and the fourth switching device Q4 can be transistors or MOSFETs. For example... Figure 3 As shown, the third switching device Q3 can be an NPN transistor, and the fourth switching device Q4 can be a PNP transistor. Alternatively, the third switching device Q3 can also be an NMOS transistor, and the fourth switching device Q4 can also be a PMOS transistor; no specific limitation is made here.

[0064] In a more specific embodiment, the second switching circuit 14 further includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10; the anode of the Zener diode is connected to the first terminal of the third switching device through the seventh resistor R7, the second terminal of the third switching device is connected to the first terminal of the fourth switching device through the ninth resistor R9, the first terminal of the eighth resistor R8 is connected to the first terminal of the third switching device, and the second terminal of the eighth resistor R8 and the third terminal of the third switching device are both grounded; the second terminal of the fourth switching device is connected to the load 22, the third terminal of the fourth switching device and the first terminal of the tenth resistor R10 are both connected to the power supply terminal 23, and the second terminal of the tenth resistor R10 is connected to the first terminal of the fourth switching device.

[0065] In this embodiment, refer to Figure 3 The seventh resistor R7 and the ninth resistor R9 act as current-limiting resistors to prevent excessive current from burning out the components connected in series. The eighth resistor R8 acts as a pull-down resistor, and the tenth resistor R10 acts as a pull-up resistor, ensuring that the first terminals (i.e., control terminals) of the third switching device Q3 and the fourth switching device Q4 will not be mis-turned on even if they are disturbed, without receiving a control signal.

[0066] In a more specific embodiment, the second switching circuit 14 further includes a freewheeling diode D2; the cathode of the freewheeling diode D2 is connected to the node where the fourth switching device Q4 and the load 22 are connected, and the anode of the freewheeling diode D2 is grounded.

[0067] In this embodiment, the freewheeling diode D2 is connected in parallel with the load 22. The load 22 of some electrical devices is an inductive load. The parallel connection of the freewheeling diode D2 provides a low-impedance path for the current in the inductor when the inductive load 22 is de-energized, preventing high voltage from damaging the circuit. Alternatively, if the load 22 to be controlled is a non-inductive load 22, the freewheeling diode D2 can be omitted.

[0068] The electrical equipment of this invention is provided with a fault safety control circuit based on a watchdog chip as described in any of the foregoing embodiments. The watchdog chip 11 monitors the operating status of the main control chip 21, and then controls the operation of the load 22 based on the output signal of the watchdog chip 11. When the main control chip 21 fails, the load 22 can be powered off and stopped working, ensuring the safe use of the electrical equipment.

[0069] Please see Figure 4 , Figure 4 This is a schematic flowchart of a fault-safe control method provided in one embodiment of the present invention. The present invention also provides a fault-safe control method applied to electrical equipment as described in any of the foregoing embodiments, the fault-safe control method comprising steps S11 to S13.

[0070] S11. When the watchdog chip does not receive a feeding signal from the main control chip within a preset time period, it outputs a pulse signal to indicate that the main control chip is in an abnormal operating state.

[0071] In this embodiment, the main control chip sends a periodic "feed" signal to the watchdog chip during normal operation, and stops sending "feed" signals during abnormal operation. The watchdog chip determines the operating status of the main control chip by monitoring whether the main control chip sends a "feed" signal within a preset time period, and outputs different signals according to the operating status of the main control chip. When the watchdog chip does not receive a "feed" signal from the main control chip within the preset time period, the watchdog chip determines that the main control chip is in an abnormal operating state, that is, the main control chip has failed, and the watchdog chip outputs a pulse signal.

[0072] S12. In response to the pulse signal, the first switching circuit alternately connects and disconnects the connection between the power supply terminal and the charging and discharging circuit, so that the voltage across the charging and discharging circuit is less than a preset threshold.

[0073] In this embodiment, the first switching circuit responds to the pulse signal output by the watchdog chip, turning on during the high level of the pulse signal and turning off during the low level of the pulse signal. That is, the first switching circuit periodically turns on and off according to the pulse signal, thereby alternately connecting and disconnecting the connection between the power supply terminal and the charging and discharging circuit. When the first switching circuit is on, the connection between the charging and discharging circuit and the power supply terminal is connected, and the power supply terminal charges the charging and discharging circuit. When the first switching circuit is off, the connection between the charging and discharging circuit and the power supply terminal is disconnected, and the charging and discharging circuit discharges. During the alternating charging and discharging process, because the charging time is too short, all the stored energy is released, resulting in the voltage across its terminals being less than a preset threshold.

[0074] S13. When the voltage across the charging and discharging circuit is less than the preset threshold, the second switching circuit disconnects the connection between the power supply terminal and the load.

[0075] In this embodiment, since the on / off state of the second switch circuit is controlled by the voltage across the charging and discharging circuit, when the voltage across the charging and discharging circuit is less than a preset threshold due to alternating charging and discharging, the second switch circuit is turned off, thereby cutting off the connection between the power supply and the load. This ensures that the load is powered off and stops working when the main control chip fails, thus ensuring the safe use of electrical equipment.

[0076] In one implementation, please refer to Figure 5 , Figure 5 This is a flowchart illustrating a fault-safe control method according to another embodiment of the present invention. The fault-safe control method further includes steps S14-S16.

[0077] S14. When the watchdog chip receives the dog-feeding signal sent by the main control chip within the preset time period, it outputs a high-level signal to indicate that the main control chip is in normal operating condition. S15. In response to the high-level signal, the first switching circuit connects the power supply terminal and the charging / discharging circuit to enable the charging / discharging circuit to continuously charge. S16. When the voltage across the charging and discharging circuit is greater than the preset threshold, the second switching circuit connects the power supply terminal to the load.

[0078] In this embodiment, when the watchdog chip receives a "feed" signal from the main control chip within a preset time period, the watchdog chip determines that the main control chip is operating normally, i.e., the main control chip is operating normally without malfunction, and the watchdog chip outputs a high-level signal. Then, the first switching circuit is turned on in response to the high-level signal output by the watchdog chip, thereby continuously connecting the power supply terminal and the charging / discharging circuit. At this time, the power supply terminal continuously charges the charging / discharging circuit. Finally, when the voltage across the charging / discharging circuit exceeds a preset threshold due to continuous charging, the second switching circuit is turned on, thereby connecting the power supply terminal and the load, allowing the load to be powered on and operate normally.

[0079] The fault safety control method provided in this embodiment of the invention is applied to electrical equipment as described in any of the foregoing embodiments. It monitors the operating status of the main control chip through a watchdog chip, and then controls the operation of the load based on the output signal of the watchdog chip. It can control the load to cut off power and stop working when the main control chip fails, thus ensuring the safe use of electrical equipment.

[0080] This invention provides a fault-safe control circuit, electrical device, and method based on a watchdog chip. The circuit includes a watchdog chip, a first switching circuit, a charging / discharging circuit, and a second switching circuit connected in sequence. The watchdog chip is also connected to a main control chip. The first switching circuit is also connected to a power supply terminal and the charging / discharging circuit. The second switching circuit is also connected to a load and the power supply terminal. The watchdog chip outputs a pulse signal when it does not receive a "feed" signal from the main control chip within a preset time period, indicating that the main control chip is in an abnormal operating state. The first switching circuit, in response to the pulse signal, alternately connects and disconnects the connection between the power supply terminal and the charging / discharging circuit, causing the voltage across the charging / discharging circuit to be less than a preset threshold. The second switching circuit disconnects the connection between the power supply terminal and the load when the voltage across the charging / discharging circuit is less than the preset threshold. This invention monitors the operating status of the main control chip using a watchdog chip, and then controls the operation of the load based on the output signal of the watchdog chip. It can control the load to stop working when the main control chip fails, ensuring the safe use of the electrical device.

[0081] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A watchdog chip based fail-safe control circuit, characterized by, The circuit is applied to an electric appliance body, and the electric appliance body comprises a master control chip, a load and a power supply end. The watchdog chip is also connected with the master control chip, the first switch circuit is also connected with the power supply end, and the second switch circuit is also connected with the load and the power supply end. The watchdog chip is configured to output a pulse signal to indicate that the master control chip is in an abnormal running state when no feeding signal sent by the master control chip is received within a preset time period.

2. The watchdog chip based fail-safe control circuit of claim 1, wherein, The first switch circuit comprises a first switch device and a second switch device.

3. The watchdog chip based fail-safe control circuit of claim 2, wherein, The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor.

4. The watchdog chip-based failsafe control circuit of claim 1, wherein, The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor.

5. The watchdog chip-based failsafe control circuit of claim 1, wherein, The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor. The first switch circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a 6. The watchdog chip based fail-safe control circuit of claim 5, wherein, The second switch circuit further comprises a seventh resistor, an eighth resistor, a ninth resistor and a tenth resistor; an anode of the voltage stabilizing diode is connected with a first end of the third switch device through the seventh resistor, a second end of the third switch device is connected with a first end of the fourth switch device through the ninth resistor, a first end of the eighth resistor is connected with the first end of the third switch device, and a second end of the eighth resistor and a third end of the third switch device are both grounded; a second end of the fourth switch device is connected with the load, a third end of the fourth switch device and a first end of the tenth resistor are both connected with the power supply end, and a second end of the tenth resistor is connected with a first end of the fourth switch device.

7. The watchdog chip based fail-safe control circuit of claim 5, wherein, The second switch circuit further comprises a freewheeling diode; a cathode of the freewheeling diode is connected with a node at which the fourth switch device and the load are connected, and an anode of the freewheeling diode is grounded.

8. An electrical appliance, characterized in that The electric appliance comprises an electric appliance body and a watchdog chip-based fault safety control circuit as claimed in any one of claims 1-7, the electric appliance body comprises a master control chip, a load and a power supply end, and the watchdog chip-based fault safety control circuit comprises a watchdog chip, a first switch circuit, a charge-discharge circuit and a second switch circuit connected in sequence; the watchdog chip is further connected with the master control chip, the first switch circuit is further connected with the power supply end and the load, and the second switch circuit is further connected with the load and the power supply end.

9. A fail-safe control method characterized by, The method is applied to the electric appliance as claimed in claim 8, and the method comprises: The watchdog chip outputs a pulse signal to indicate that the master control chip is in an abnormal running state when the watchdog chip does not receive a feed signal sent by the master control chip within a preset time period; The first switch circuit alternately connects and disconnects a connection between the power supply end and the charge-discharge circuit in response to the pulse signal, so that a voltage across the charge-discharge circuit is less than a preset threshold value; The second switch circuit disconnects a connection between the power supply end and the load when the voltage across the charge-discharge circuit is less than the preset threshold value.

10. The fail-safe control method according to claim 9, characterized by, Further comprising: The watchdog chip outputs a high-level signal to indicate that the master control chip is in a normal running state when the watchdog chip receives the feed signal sent by the master control chip within the preset time period; The first switch circuit connects the connection between the power supply end and the charge-discharge circuit in response to the high-level signal, so that the charge-discharge circuit is continuously charged; The second switch circuit connects the connection between the power supply end and the load when the voltage across the charge-discharge circuit is greater than the preset threshold value.

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