Self-protection heating circuit

Abstract

The invention discloses a self-protection heating circuit which comprises a self-protection circuit, an MCU controller circuit and a heating circuit, a thermistor and a voltage division protection circuit are arranged in the self-protection circuit, the thermistor emits heat when working, and the resistance value changes along with the temperature. The voltage division protection circuit is configured to control the voltage at the output end of the voltage division protection circuit according to the change of the resistance value of the thermistor and control whether the heating circuit is conducted or not according to the output end of the voltage division protection circuit; the heating circuit is configured to perform heating when the voltage at the output end of the voltage division protection circuit controls the heating circuit to be switched on, and stop heating when the voltage at the output end of the voltage division protection circuit controls the heating circuit to be switched off; and the MCU controller circuit outputs a PWM control signal to the self-protection circuit, and determines the highest heating temperature of the heating circuit according to the PWM control signal. The self-protection circuit is arranged to control whether the heating circuit is conducted or not according to the heating temperature, and safety accidents caused by continuous heating of the heating circuit are avoided.

Description

Technical Field

[0001] The present application relates to the field of circuits, and in particular, to a self-protection heating circuit. Background Art

[0002] In the prior art, most heating devices generate heat by setting up a heating circuit, and current flows through the conductor to convert electrical energy into thermal energy to achieve heating. However, when the heating circuit continues to heat the conductor, it may cause a safety accident. If current flows through the conductor for a long time, it may cause a safety accident.

[0003] Therefore, the heating circuit in the prior art has the problem of low circuit reliability. Summary of the invention

[0004] The main purpose of the present application is to provide a self-protection heating circuit to solve the technical problem of low circuit reliability in the prior art heating circuit, thereby achieving the technical effect of improving the safety of the heating circuit.

[0005] In order to achieve the above-mentioned purpose, the first aspect of the present application proposes a self-protection heating circuit, characterized in that it includes: a self-protection circuit, an MCU controller circuit, and a heating circuit, wherein:

[0006] The self-protection circuit is provided with a thermistor and a voltage-dividing protection circuit. The thermistor generates heat during operation and its resistance value changes with temperature. The voltage-dividing protection circuit is configured to control the voltage at the output end of the voltage-dividing protection circuit according to the change in the resistance value of the thermistor, and to control whether the heating circuit is turned on according to the output end of the voltage-dividing protection circuit;

[0007] The heating circuit is configured such that when the voltage at the output end of the voltage-dividing protection circuit controls the heating circuit to be turned on, the heating circuit performs heating, and when the voltage at the output end of the voltage-dividing protection circuit controls the heating circuit to be turned off, the heating circuit stops heating;

[0008] The MCU controller circuit outputs a PWM control signal to the self-protection circuit, and determines the maximum heating temperature of the heating circuit according to the PWM control signal.

[0009] In some optional embodiments of the present application,

[0010] The self-protection circuit includes a first transistor, and the first transistor is configured to control the first transistor to be turned on or off according to the output voltage of the voltage-dividing protection circuit.

[0011] In some optional embodiments of the present application,

[0012] When the first transistor is turned on, the heating circuit is turned on, and the heating circuit performs heating;

[0013] When the first transistor is turned off, the heating circuit is disconnected and stops heating.

[0014] In some optional embodiments of the present application,

[0015] The MCU controller input end is coupled to the temperature detection circuit, receives the temperature signal of the temperature detection circuit, generates a PWM signal with a corresponding duty cycle according to the temperature signal, and outputs the PWM signal to the heating self-protection circuit.

[0016] In some optional embodiments of the present application,

[0017] The temperature detection circuit includes a temperature sensor, and the temperature sensor is arranged at a position close to the heating circuit to detect the temperature change of the heating circuit.

[0018] In some optional embodiments of the present application, the device comprises: a first thermistor, a second thermistor, a third resistor, a fourth resistor, a first transistor, a second transistor, a first capacitor, a second capacitor, an MCU controller,

[0019] A first terminal of the first thermistor is coupled to a first supply voltage, and a second terminal of the first thermistor is coupled to a first terminal of the second thermistor;

[0020] The second terminal of the second thermistor is coupled to the first terminal of the third resistor;

[0021] The second end of the third resistor is coupled to the first electrode of the second transistor;

[0022] A first end of the fourth resistor is coupled to the gate of the second transistor, and a second end of the fourth resistor is grounded;

[0023] A first electrode of the first transistor is coupled to a second end of the first thermistor, a second electrode of the first transistor is coupled to a second power supply voltage, and a gate of the first transistor is coupled to a second end of the second thermistor;

[0024] The gate of the second transistor is coupled to the output terminal of the MCU controller circuit, and the second electrode of the second transistor is grounded;

[0025] A first terminal of the first capacitor is coupled to the gate of the first transistor, and a second terminal of the first capacitor is coupled to the second electrode of the second transistor;

[0026] A first terminal of the second capacitor is coupled to the gate of the second transistor, and a second terminal of the second capacitor is grounded.

[0027] In some optional embodiments of the present application,

[0028] The first thermistor is a positive temperature coefficient thermistor, and the second thermistor is a negative temperature coefficient thermistor. The first thermistor and the second thermistor are arranged at close positions so that the temperature generated by the operation of the first thermistor controls the change of the resistance value of the second thermistor.

[0029] In some optional embodiments of the present application,

[0030] The first transistor is a PMOS transistor, and the second transistor is an NMOS transistor.

[0031] In some optional embodiments of the present application,

[0032] As the operating temperature of the first thermistor increases, the resistance value of the first thermistor increases, and the resistance value of the second thermistor decreases, until the first transistor is turned off, thereby shutting down the power supply circuit of the heating circuit.

[0033] In some optional embodiments of the present application,

[0034] The first thermistor is a positive temperature coefficient thermistor PTC. If the first transistor is short-circuited, the first supply voltage directly powers the heating circuit, generating a transient large current, the resistance of the first thermistor increases, the heating circuit is disconnected, and the heating circuit stops heating.

[0035] The technical solution provided by the embodiments of the present application may have the following beneficial effects:

[0036] In the present application, a self-protection heating circuit is proposed, including: a self-protection circuit, an MCU controller circuit, and a heating circuit. The self-protection circuit is provided with a thermistor and a voltage-dividing protection circuit. The thermistor generates heat during operation and its resistance value changes with temperature. The voltage-dividing protection circuit is configured to control the voltage at the output end of the voltage-dividing protection circuit according to the change in the resistance value of the thermistor, and to control whether the heating circuit is turned on according to the output end of the voltage-dividing protection circuit; the heating circuit is configured to heat when the voltage at the output end of the voltage-dividing protection circuit controls the heating circuit to be turned on, and to stop heating when the voltage at the output end of the voltage-dividing protection circuit controls the heating circuit to be turned off; the MCU controller circuit outputs a PWM control signal to the self-protection circuit, and determines the maximum heating temperature of the heating circuit according to the PWM control signal. The self-protection circuit is set to control whether the heating circuit is turned on according to the heating temperature, so as to avoid safety accidents caused by continuous heating of the heating circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings constituting a part of this application are used to provide a further understanding of this application, so that other features, purposes and advantages of this application become more obvious. The schematic embodiment drawings and their descriptions of this application are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0038] Figure 1 A schematic diagram of a heating self-protection circuit provided in an embodiment of the present application;

[0039] Figure 2 A schematic diagram of a heating self-protection circuit provided in an embodiment of the present application;

[0040] Figure 3 A circuit diagram of a heating self-protection circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0042] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0043] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0044] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0045] In addition, the terms "installed", "set", "provided with", "connected", "connected", and "socketed" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0046] In all embodiments of the present disclosure, since the source and drain of a metal oxide semiconductor (MOS) transistor are symmetrical, and the conduction current directions between the source and drain of an N-type transistor and a P-type transistor are opposite, in the embodiments of the present disclosure, the controlled middle end of the MOS transistor is referred to as a control electrode, and the remaining two ends of the MOS transistor are referred to as a first electrode and a second electrode, respectively. The transistors used in the embodiments of the present disclosure are mainly switching transistors. In addition, terms such as "first" and "second" are only used to distinguish one component (or a portion of a component) from another component (or another portion of a component).

[0047] In the prior art, most heating devices generate heat by setting up a heating circuit, and current flows through the conductor to convert electrical energy into thermal energy to achieve heating. However, when the heating circuit continues to heat the conductor, it may cause a safety accident. If the conductor has current flowing through it for a long time, it may cause a safety accident. Therefore, the heating circuit in the prior art has the problem of low circuit reliability.

[0048] In an optional embodiment of the present application, a self-protection heating circuit is proposed. Figure 1 A schematic diagram of a self-protection heating circuit provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the self-protection heating circuit includes: a self-protection circuit 100, a heating circuit 200, and an MCU controller circuit 300, wherein:

[0049] The self-protection circuit 100 is provided with a thermistor 110 and a voltage-dividing protection circuit 120. The thermistor 110 generates heat when working and its resistance value changes with temperature. The voltage-dividing protection circuit 120 is configured to control the voltage at the output end of the voltage-dividing protection circuit 120 according to the change of the resistance value of the thermistor 110, and control whether the heating circuit 200 is turned on according to the output end of the voltage-dividing protection circuit 120;

[0050] The heating circuit 200 is configured such that when the voltage at the output end of the voltage-dividing protection circuit 120 controls the heating circuit 200 to be turned on, the heating circuit 200 performs heating, and when the voltage at the output end of the voltage-dividing protection circuit 120 controls the heating circuit to be turned off, the heating circuit 200 stops heating;

[0051] The MCU controller circuit 300 outputs a PWM control signal to the self-protection circuit 100 , and determines the maximum heating temperature of the heating circuit 200 according to the PWM control signal.

[0052] In another optional embodiment of the present application, a self-protection heating circuit is proposed, wherein the self-protection circuit 100 includes a thermistor, a voltage divider protection circuit and a first transistor, the thermistor includes a first thermistor and a second thermistor, wherein the first thermistor is a positive temperature coefficient thermistor, the second thermistor is a negative temperature coefficient thermistor, and the second thermistor is arranged at a position close to the first thermistor. When the self-protection heating circuit is working, current flows through the first thermistor, the first thermistor works and generates heat, the resistance value of the first thermistor increases, and the resistance value of the second thermistor decreases as the temperature of the first thermistor increases. As the resistance values ​​of the first thermistor and the second thermistor change, the voltage at the output end of the voltage divider protection circuit is reduced. When the voltage at the output end of the voltage divider protection circuit decreases to a preset state, the first transistor is disconnected, the heating circuit is disconnected, and the heating circuit stops heating. By setting the thermistor and the voltage divider protection circuit, the voltage at the output end of the voltage divider protection circuit is controlled to change with the temperature change, and the first transistor is controlled to be turned on or off, so as to realize the control of whether the heating circuit is continuously heated, and avoid the safety hazard caused by the continuous heating temperature rise of the heating circuit.

[0053] In another optional embodiment of the present application, a self-protection heating circuit is proposed, in which the output end of the voltage divider protection circuit is coupled to the gate of the first transistor. When the voltage at the output end of the voltage divider protection circuit is insufficient to turn on the first transistor, the first transistor is cut off, the heating circuit is disconnected, and the heating circuit stops heating; when the voltage at the output end of the voltage divider protection circuit turns on the first transistor, the first transistor is turned on, the heating circuit is turned on, and the heating circuit starts heating.

[0054] In another optional embodiment of the present application, a self-protection heating circuit is proposed, wherein the self-protection heating circuit includes an MCU controller circuit, the MCU controller circuit includes an MCU controller and a temperature detection circuit, the MCU controller input end is coupled to the temperature detection circuit, receives the temperature signal of the temperature detection circuit, the MCU controller generates a PWM signal with a corresponding duty cycle according to the temperature signal, and outputs the PWM signal to the heating self-protection circuit.

[0055] In another optional embodiment of the present application, a self-protection heating circuit is provided. Figure 2 A circuit diagram of a self-protection heating circuit provided in this application, such as Figure 2 As shown, the self-protection heating circuit includes:

[0056] The temperature detection circuit includes a temperature sensor, and the temperature sensor is arranged at a position close to the heating circuit to detect the temperature change of the heating circuit.

[0057] In an embodiment of the present application, when the self-protection heating circuit starts to work, the MCU controller outputs a PWM signal to control the switch of the second transistor Q2 on the low-voltage side. The on and off of the second transistor Q2 controls the switch of the first transistor on the high-voltage side, and the heating circuit starts to be powered on for heating. The temperature sensor in the temperature detection circuit detects the temperature change of the heating unit in the heating circuit in real time. The temperature detection circuit transmits the detected temperature of the heating unit to the MCU controller. A temperature adjustment algorithm is built into the MCU controller. The duty cycle of the PWM signal output by the MCU is adjusted in real time according to the temperature of the heating unit transmitted back, thereby realizing the temperature control of the heating unit. The temperature control of the processing unit according to the duty cycle of the output PWM signal is: P (heating unit) = V_B*V_B / R (impedance of the heating unit), V_B = Vp*D (D is the duty cycle of PWM), P is the heating power of the heating power supply, and according to the above temperature control scheme, the temperature is adjusted in real time by adjusting the duty cycle D of the PWM signal output by the MCU to realize the temperature control of the heating unit.

[0058] In another optional embodiment of the present application, a self-protection heating circuit is provided. Figure 3 A circuit diagram of a self-protection heating circuit provided in this application, such as Figure 3 As shown, the self-protection heating circuit includes: a first thermistor R1, a second thermistor R2, a third resistor R3, a fourth resistor R4, a first transistor Q1, a second transistor Q2, a first capacitor C1, a second capacitor C2, an MCU controller,

[0059] A first terminal of the first thermistor R1 is coupled to a first power supply voltage Vp, and a second terminal of the first thermistor R1 is coupled to a first terminal of the second thermistor R2;

[0060] The second end of the second thermistor R2 is coupled to the first end of the third resistor R3;

[0061] The second end of the third resistor R3 is coupled to the first electrode of the second transistor Q2;

[0062] A first end of the fourth resistor R4 is coupled to the gate of the second transistor Q2, and a second end of the fourth resistor R4 is grounded;

[0063] A first electrode of the first transistor Q1 is coupled to a second end of the first thermistor R1, a second electrode of the first transistor Q1 is coupled to a second power supply voltage V_B, and a gate of the first transistor Q1 is coupled to a second end of the second thermistor R2;

[0064] The gate of the second transistor Q2 is coupled to the output terminal of the MCU controller circuit, and the second electrode of the second transistor Q2 is grounded;

[0065] A first end of the first capacitor C1 is coupled to the gate of the first transistor Q1, and a second end of the first capacitor C1 is coupled to the second electrode of the second transistor Q2;

[0066] A first terminal of the second capacitor C2 is coupled to the gate of the second transistor Q2 , and a second terminal of the second capacitor C2 is grounded.

[0067] In another optional embodiment of the present application,

[0068] The first thermistor R1 is a positive temperature coefficient thermistor RPTC, and the second thermistor R2 is a negative temperature coefficient thermistor RNTC. The first thermistor R1 and the second thermistor R2 are arranged at close positions so that the temperature generated by the operation of the first thermistor controls the change of the resistance value of the second thermistor.

[0069] In another optional embodiment of the present application, the first transistor is a PMOS transistor, and the second transistor is an NMOS transistor.

[0070] In another optional embodiment of the present application,

[0071] As the operating temperature of the first thermistor increases, the resistance value of the first thermistor increases, and the resistance value of the second thermistor decreases, until the first transistor is turned off, thereby shutting down the power supply circuit of the heating circuit.

[0072] In another optional embodiment of the present application, a self-protection heating circuit is provided, wherein:

[0073] The first thermistor is a positive temperature coefficient thermistor PTC. If the first transistor is short-circuited, the first supply voltage directly powers the heating circuit, generating a transient large current, the resistance of the first thermistor increases, the heating circuit is disconnected, and the heating circuit stops heating.

[0074] In an embodiment of the present application, when the first transistor Q1 fails and breaks down, the first transistor Q1 is short-circuited, and the first thermistor is a positive temperature coefficient thermistor PTC. Since the first transistor Q1 breaks down and short-circuit, and the load heating circuit is a high-power heating wire, the first power supply voltage directly powers the heating circuit, generating a transient large current, and the resistance of the first thermistor increases sharply, so as to cut off the output of the first power supply to the first transistor Q1, the heating circuit is disconnected from the first power supply voltage, and the heating circuit stops heating.

[0075] In an embodiment of the present application, a self-protection heating circuit is set up based on a thermistor and a voltage divider protection circuit. As the heating temperature increases, the resistance of the thermistor changes, and the voltage output by the voltage divider circuit to the heating circuit is adjusted to control the conduction or disconnection of the heating circuit. This achieves the goal of disconnecting the power supply to the heating circuit under high current conditions, protecting electronic equipment and avoiding damage to electronic equipment and other safety risks caused by continuous heating due to continuous temperature rise.

[0076] Those skilled in the art will understand that Figure 3 The internal structure of the heating circuit 200 in the embodiment is exemplary, and the heating circuit 200 may also be implemented by other circuits. The embodiments of the present disclosure do not limit the specific implementation of the heating circuit 200.

[0077] In summary, in the present application, a self-protection heating circuit is proposed, including: a self-protection circuit, an MCU controller circuit, and a heating circuit. The self-protection circuit is provided with a thermistor and a voltage divider protection circuit. The thermistor generates heat during operation and its resistance value changes with temperature. The voltage divider protection circuit is configured to control the voltage at the output end of the voltage divider protection circuit according to the change in the resistance value of the thermistor, and to control whether the heating circuit is turned on according to the output end of the voltage divider protection circuit; the heating circuit is configured to heat when the voltage at the output end of the voltage divider protection circuit controls the heating circuit to be turned on, and to stop heating when the voltage at the output end of the voltage divider protection circuit controls the heating circuit to be turned off; the MCU controller circuit outputs a PWM control signal to the self-protection circuit, and determines the maximum heating temperature of the heating circuit according to the PWM control signal. The self-protection circuit is set to control whether the heating circuit is turned on according to the heating temperature, so as to avoid safety accidents caused by continuous heating of the heating circuit.

[0078] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0079] Obviously, those skilled in the art should understand that the above-mentioned units or steps of the present application can be implemented by a general-purpose computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, and optionally, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. In this way, the present application is not limited to any specific combination of hardware and software.

[0080] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A self-protection heating circuit, characterized in that: include: Self-protection circuit, MCU controller circuit, heating circuit, among which, The self-protection circuit is provided with a thermistor and a voltage-dividing protection circuit. The thermistor generates heat during operation and its resistance value changes with temperature. The voltage-dividing protection circuit is configured to control the voltage at the output end of the voltage-dividing protection circuit according to the change in the resistance value of the thermistor, and to control whether the heating circuit is turned on according to the output end of the voltage-dividing protection circuit; The heating circuit is configured such that when the voltage at the output end of the voltage-dividing protection circuit controls the heating circuit to be turned on, the heating circuit performs heating, and when the voltage at the output end of the voltage-dividing protection circuit controls the heating circuit to be turned off, the heating circuit stops heating; The MCU controller circuit outputs a PWM control signal to the self-protection circuit, and determines the maximum heating temperature of the heating circuit according to the PWM control signal.

2. The self-protection heating circuit according to claim 1, characterized in that: The self-protection circuit includes a first transistor, and the first transistor is configured to control the first transistor to be turned on or off according to the output voltage of the voltage-dividing protection circuit.

3. The self-protection heating circuit according to claim 2, characterized in that: When the first transistor is turned on, the heating circuit is turned on, and the heating circuit performs heating; When the first transistor is turned off, the heating circuit is disconnected and stops heating.

4. The self-protection heating circuit according to claim 1, characterized in that: The MCU controller input end is coupled to the temperature detection circuit, receives the temperature signal of the temperature detection circuit, generates a PWM signal with a corresponding duty cycle according to the temperature signal, and outputs the PWM signal to the heating self-protection circuit.

5. The self-protection heating circuit according to claim 4, characterized in that: The temperature detection circuit includes a temperature sensor, and the temperature sensor is arranged at a position close to the heating circuit to detect the temperature change of the heating circuit.

6. The self-protection heating circuit according to claim 1, characterized in that: include: a first thermistor, a second thermistor, a third resistor, a fourth resistor, a first transistor, a second transistor, a first capacitor, a second capacitor, an MCU controller, A first terminal of the first thermistor is coupled to a first supply voltage, and a second terminal of the first thermistor is coupled to a first terminal of the second thermistor; The second terminal of the second thermistor is coupled to the first terminal of the third resistor; The second end of the third resistor is coupled to the first electrode of the second transistor; A first end of the fourth resistor is coupled to the gate of the second transistor, and a second end of the fourth resistor is grounded; A first electrode of the first transistor is coupled to a second end of the first thermistor, a second electrode of the first transistor is coupled to a second power supply voltage, and a gate of the first transistor is coupled to a second end of the second thermistor; The gate of the second transistor is coupled to the output terminal of the MCU controller circuit, and the second electrode of the second transistor is grounded; A first terminal of the first capacitor is coupled to the gate of the first transistor, and a second terminal of the first capacitor is coupled to the second electrode of the second transistor; A first terminal of the second capacitor is coupled to the gate of the second transistor, and a second terminal of the second capacitor is grounded.

7. The self-protection heating circuit according to claim 6, characterized in that: The first thermistor is a positive temperature coefficient thermistor, and the second thermistor is a negative temperature coefficient thermistor. The first thermistor and the second thermistor are arranged at close positions so that the temperature generated by the operation of the first thermistor controls the change of the resistance value of the second thermistor.

8. The self-protection heating circuit according to claim 6, characterized in that: The first transistor is a PMOS transistor, and the second transistor is an NMOS transistor.

9. The self-protection heating circuit according to claim 6, characterized in that: As the operating temperature of the first thermistor increases, the resistance value of the first thermistor increases, and the resistance value of the second thermistor decreases, until the first transistor is turned off, thereby shutting down the power supply circuit of the heating circuit.

10. The self-protection heating circuit according to claim 6, characterized in that: The first thermistor is a positive temperature coefficient thermistor PTC. If the first transistor is short-circuited, the first supply voltage directly powers the heating circuit, generating a transient large current, the resistance of the first thermistor increases, the heating circuit is disconnected, and the heating circuit stops heating.

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