Temperature control protection circuit

Abstract

The utility model provides a temperature control protection circuit, and relates to the technical field of circuit protection. The temperature detection sub-circuit converts temperature information into a voltage signal which is negatively correlated with the external temperature, and the first signal processing sub-circuit carries out temperature judgment based on the voltage signal. When the temperature exceeds a preset threshold value, the external power supply is grounded through the first signal processing sub-circuit, so that the control end of the second signal processing sub-circuit receives a low-level signal; the second signal processing sub-circuit is used for forbidding the external power supply to be grounded through the second signal processing sub-circuit, so that the control end of the driving control sub-circuit receives a high-level signal; according to the invention, high-sensitivity turn-on is realized, meanwhile, the problem of linear region change does not exist in the turn-on process, and the possible unstable state is avoided.

Description

Technical Field

[0001] The present application relates to the field of circuit protection technology, and in particular to a temperature control protection circuit. Background Art

[0002] With the continuous development of electronic devices, the requirements for power management chips are becoming increasingly higher. In various electronic products, power management chips need to have multiple protection functions. Among them, overtemperature protection is one of the key functions to ensure the safe operation of the equipment. Overtemperature protection can take timely measures when the chip temperature is too high, preventing chip damage due to overheating, thereby improving product reliability and service life.

[0003] Currently, common methods for implementing overtemperature protection include using a microcontroller with an NTC (negative temperature coefficient thermistor) and a comparator. In the MCU-plus-NTC solution, the temperature is determined by reading the NTC voltage through the MCU's analog-to-digital converter (ADC). This method uses a programmable temperature threshold; when the temperature exceeds the threshold, the protection mechanism is triggered. In the comparator solution, the NTC voltage is compared with a preset reference voltage. When the temperature exceeds the threshold, the comparator outputs a trigger signal, thus achieving overtemperature protection.

[0004] However, these related technologies have some problems in practical applications. For the solution of single-chip microcomputer plus NTC, the ADC accuracy of single-chip microcomputers with different bit numbers may lead to large differences in temperature detection accuracy. For example, if an 8-bit single-chip microcomputer is used, the error is 1 / 2 8 =39mV, the error of 12-bit microcontroller is 1 / 2 12 =9.6mV, which cannot meet the requirements of high-precision temperature control. Utility Model Content

[0005] This application provides a temperature control protection circuit to improve detection accuracy.

[0006] In a first aspect, the present application provides a temperature control protection circuit, comprising: a temperature detection subcircuit, a first signal processing subcircuit, a second signal processing subcircuit and a drive control subcircuit.

[0007] The input end of the temperature detection subcircuit is connected to the external power supply, and the output end is connected to the control end of the first signal processing subcircuit, and is used to control the voltage between the external power supply and the control end of the first signal processing subcircuit, wherein the voltage is negatively correlated with the external temperature; the input end of the first signal processing subcircuit is commonly connected to the control end of the second signal processing subcircuit and the external power supply, and the output end is connected to the ground; when the voltage at the control end of the first signal processing subcircuit is not greater than the preset temperature control threshold, the external power supply is prohibited from being connected to the ground through the first signal processing subcircuit, so that the control end of the second signal processing subcircuit receives a high-level signal; when the voltage at the control end of the first signal processing subcircuit is greater than the preset threshold, the external power supply is allowed to be connected to the ground through the first signal processing subcircuit, so that the control end of the second signal processing subcircuit receives a low-level signal; the input end of the second signal processing subcircuit is connected to the external power supply and the input end of the drive control subcircuit The output end of the drive control subcircuit is connected to the control end of the first signal processing subcircuit and the external output end, and is used for, when the control end of the second signal processing subcircuit receives a high-level signal, allowing the external power supply to be connected to the ground through the second signal processing subcircuit, so that the control end of the drive control subcircuit receives a low-level signal; when the control end of the second signal processing subcircuit receives a low-level signal, prohibiting the external power supply from being connected to the ground through the second signal processing subcircuit, so that the control end of the drive control subcircuit receives a high-level signal; the output end of the drive control subcircuit is connected to the control end of the first signal processing subcircuit and the external output end, and is used for, when the control end of the drive control subcircuit receives a low-level signal, not outputting a signal from the external output end; when the control end of the drive control subcircuit receives a high-level signal, outputting a high signal to the control end of the first signal processing subcircuit to saturate and conduct, and outputting a signal through the external output end.

[0008] By adopting the above technical solution, the temperature detection subcircuit converts temperature information into a voltage signal that is negatively correlated with the external temperature. The first signal processing subcircuit performs temperature determination based on this voltage signal. When the temperature exceeds a preset threshold, the external power supply is connected to the ground through the first signal processing subcircuit, causing the control terminal of the second signal processing subcircuit to receive a low-level signal. The second signal processing subcircuit prohibits the external power supply from being connected to the ground through the second signal processing subcircuit, causing the control terminal of the drive control subcircuit to receive a high-level signal. The drive control subcircuit turns on the output signal and, by outputting a high signal to the control terminal of the first signal processing subcircuit, causes it to rapidly saturate and conduct. The high signal output by the drive control subcircuit causes the first signal processing subcircuit to rapidly saturate and conduct, achieving high-sensitivity switching. Furthermore, the switching process avoids linear region variations, thus avoiding potential instability.

[0009] In combination with some embodiments of the first aspect, in some embodiments, the circuit also includes a first voltage divider filter sub-circuit; the output end of the temperature detection sub-circuit is connected to the control end of the first signal processing sub-circuit through the first voltage divider filter sub-circuit, and the first voltage divider filter sub-circuit is used to divide and filter the voltage between the output end of the temperature detection sub-circuit and the control end of the first signal processing sub-circuit.

[0010] By adopting this technical solution, the voltage divider function allows for more flexible adjustment of the temperature detection range, adapting to different application scenarios and temperature requirements. Secondly, the filtering function effectively reduces noise interference in the circuit and improves the signal-to-noise ratio of the temperature signal. These two functions combined not only improve the accuracy of temperature detection but also enhance the circuit's resistance to environmental interference.

[0011] In combination with some embodiments of the first aspect, in some embodiments, the circuit also includes a second voltage divider and filter sub-circuit; the control end of the second signal processing sub-circuit is connected to the external power supply through the second voltage divider and filter sub-circuit, and the second voltage divider and filter sub-circuit is used to divide and filter the voltage between the external power supply connection and the control end of the second signal processing sub-circuit.

[0012] By employing this technical solution, the voltage divider function allows for more precise setting of the temperature control threshold, enabling the voltage to operate normally over a wider range of power supply voltages. The filtering function effectively suppresses voltage fluctuations and noise interference from the external power supply, ensuring the stability of the control signal received by the second signal processing sub-circuit.

[0013] In combination with some embodiments of the first aspect, in some embodiments, the circuit also includes a voltage-stabilizing rectifier circuit; the output end of the drive control circuit is connected to the external output end through the voltage-stabilizing rectifier circuit; the voltage-stabilizing rectifier circuit is used to output a signal to the external output end when the voltage at the output end of the drive control circuit is greater than a preset voltage-stabilizing threshold; and the voltage-stabilizing rectifier circuit is used to prohibit the external output end from outputting voltage in reverse to the drive control circuit.

[0014] By employing these technical solutions, the voltage stabilization function ensures the stability of the output signal, providing a stable signal to the external output terminal even when the output of the drive control circuit fluctuates. Secondly, the rectification function prevents the external voltage from being reversely input into the drive control circuit, effectively protecting the internal circuit from external interference and potential damage.

[0015] In the first aspect, the present application provides a temperature control protection circuit, including: an NTC thermistor R2, a transistor Q1, a transistor Q3, and a MOS transistor Q2; an external power supply is connected to the base of the transistor Q3 through the NTC thermistor R2; the external power supply, the collector of the transistor Q3, and the gate of the MOS transistor Q2 are connected together; the emitter of the transistor Q3 is grounded; the drain of the MOS transistor Q2 is connected to the external power supply, the base of the transistor Q1, and the collector of the transistor Q1; the source of the MOS transistor Q2 is grounded; the emitter of the transistor Q1 is connected to the base of the transistor Q3 and the external output end.

[0016] In combination with some embodiments of the second aspect, in some embodiments, the circuit further includes: a resistor R8 and a capacitor C2; the NTC thermistor R2, one end of the resistor R8, one end of the capacitor C2, and the base of the transistor Q3 are connected together; the other end of the resistor R8 and the other end of the capacitor C2 are grounded.

[0017] In combination with some embodiments of the second aspect, in some embodiments, the circuit further includes: a resistor R7 and a capacitor C1; an external power supply, a collector of the transistor Q3, a gate of the MOS transistor Q2, one end of the resistor R7, and one end of the capacitor C1 are commonly connected; and the other ends of the resistor R7 and the capacitor C1 are grounded.

[0018] In combination with some embodiments of the second aspect, in some embodiments, the circuit further includes: a voltage regulator diode D1, a rectifier diode D2 and a resistor R9; the emitter of the transistor Q1 is connected to the external output end through the voltage regulator diode D1 and the rectifier diode D2; the emitter of the transistor Q1 is connected to the base of the transistor Q3 through the resistor R9.

[0019] In combination with some embodiments of the second aspect, in some embodiments, the circuit further includes: a resistor R2; and the NTC thermistor R2 is connected to the base of the transistor Q3 via the resistor R2.

[0020] In combination with some embodiments of the second aspect, in some embodiments, the circuit further includes: a resistor R3 and a resistor R5; the external power supply is connected to the base of the transistor Q1 and the collector of the transistor Q1 through the resistor R3; and the external power supply is connected to the drain of the MOS tube Q2 through the resistor R3 and the resistor R5.

[0021] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0022] 1. The temperature detection subcircuit converts temperature information into a voltage signal negatively correlated with the external temperature. The first signal processing subcircuit determines the temperature based on this voltage signal. When the temperature exceeds a preset threshold, the external power source is connected to ground through the first signal processing subcircuit, causing the control terminal of the second signal processing subcircuit to receive a low-level signal. The second signal processing subcircuit prohibits the external power source from connecting to ground through the second signal processing subcircuit, causing the control terminal of the drive control subcircuit to receive a high-level signal. The drive control subcircuit turns on the output signal and quickly saturates and conducts by outputting a high signal to the control terminal of the first signal processing subcircuit. The high signal output by the drive control subcircuit causes the first signal processing subcircuit to quickly saturate and conduct, achieving high-sensitivity turn-on. Furthermore, the turn-on process avoids linear region variations, preventing potential instability.

[0023] 2. The voltage divider function allows for more flexible adjustment of the temperature detection range, adapting to different application scenarios and temperature requirements. Secondly, the filtering function effectively reduces noise interference in the circuit and improves the signal-to-noise ratio of the temperature signal. These two functions combined not only improve the accuracy of temperature detection but also enhance the circuit's resistance to environmental interference.

[0024] 3. The voltage divider function allows for more precise setting of the temperature control threshold, enabling the voltage to operate normally over a wider range of power supply voltages. The filtering function effectively suppresses voltage fluctuations and noise interference that may be introduced by the external power supply, ensuring the stability of the control signal received by the second signal processing sub-circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a circuit block diagram of the temperature control protection circuit in the embodiment of the present application;

[0026] Figure 2 This is a circuit principle diagram of the temperature control protection circuit in the embodiment of the present application. DETAILED DESCRIPTION

[0027] The terms used in the following examples of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. As used in the specification and appended claims of the present application, the singular expressions "a," "an," "said," "above," "the," and "this" are intended to include plural expressions as well, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used in the present application refers to and encompasses any or all possible combinations of one or more of the listed items.

[0028] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to imply or suggest relative importance or implicitly indicate the number of the technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of this application, unless otherwise specified, "plurality" means two or more.

[0029] See also Figure 1 , Figure 1 This is a circuit block diagram of a temperature control protection circuit in an embodiment of the present application; the temperature control protection circuit includes: a temperature detection subcircuit, a first signal processing subcircuit, a second signal processing subcircuit and a drive control subcircuit;

[0030] The temperature detection subcircuit has an input terminal connected to an external power supply and an output terminal connected to a control terminal of the first signal processing subcircuit, and is used to control a voltage between the external power supply and the control terminal of the first signal processing subcircuit, wherein the voltage is negatively correlated with the external temperature;

[0031] The external power supply refers to the power supply that provides energy to the entire circuit. The negative correlation between voltage and external temperature means that as the temperature increases, the output voltage decreases, and vice versa.

[0032] In some embodiments, the temperature detection subcircuit receives an operating voltage from an external power source at its input. Based on changes in ambient temperature, it generates a voltage signal at its output that is inversely proportional to the temperature. This voltage signal is sent to the control terminal of the first signal processing subcircuit as input for subsequent processing. The temperature detection subcircuit effectively converts the physical quantity of temperature into the electrical quantity of voltage, providing initial temperature information for the entire temperature control circuit.

[0033] In some specific embodiments, an NTC (negative temperature coefficient) thermistor can be used to implement temperature detection. The specific steps include: selecting an NTC thermistor; connecting the NTC thermistor in series with a fixed resistor to form a voltage divider circuit; using the midpoint voltage of the voltage divider circuit as the output; and adjusting the resistance of the fixed resistor to achieve the desired temperature-voltage relationship. This is not limited here.

[0034] In other specific embodiments, an integrated temperature sensor IC can be used to implement temperature detection. Specific steps include: selecting a temperature sensor IC and connecting the sensor output to a signal processing circuit. If a digital output sensor is used, an interface circuit needs to be designed for digital-to-analog conversion. This is not limited here.

[0035] The input terminal of the first signal processing subcircuit is commonly connected to the control terminal of the second signal processing subcircuit and the external power supply, and the output terminal is connected to the ground; when the voltage at the control terminal of the first signal processing subcircuit is not greater than a preset temperature control threshold, the external power supply is prohibited from being connected to the ground through the first signal processing subcircuit, so that the control terminal of the second signal processing subcircuit receives a high-level signal; when the voltage at the control terminal of the first signal processing subcircuit is greater than the preset threshold, the external power supply is allowed to be connected to the ground through the first signal processing subcircuit, so that the control terminal of the second signal processing subcircuit receives a low-level signal;

[0036] The first signal processing subcircuit determines whether to trigger the protection mechanism by comparing the temperature-related voltage received by the control terminal with a preset temperature control threshold. When the temperature is below the threshold, the circuit maintains normal operation and outputs a high-level signal. When the temperature exceeds the threshold, the circuit switches to protection mode and outputs a low-level signal. This provides a reliable trigger signal for subsequent protection actions.

[0037] In some embodiments, a transistor-related circuit is selected to implement the first signal processing subcircuit. The specific steps include: connecting the base (control terminal) of the transistor to the output terminal of the temperature detection subcircuit, so that the temperature signal controls the switching state of the transistor; connecting the collector (input terminal) of the transistor to an external power supply through a suitable pull-up resistor (e.g., 10kΩ). This configuration ensures that the collector remains high when the transistor is off; directly grounding the emitter (output terminal) of the transistor; and connecting the control terminal of the second signal processing subcircuit to the collector of the transistor. This allows the second signal processing subcircuit to detect changes in the collector voltage. With this design, when the temperature detection subcircuit outputs a low voltage (corresponding to a low temperature), the transistor is turned off, and its collector is high. When the temperature detection subcircuit outputs a high voltage (corresponding to a high temperature), the transistor is turned on, and its collector is low. In this way, the control terminal of the second signal processing subcircuit can display high or low voltage levels related to the temperature through the switching state of the transistor, thereby processing and converting the temperature signal. This is not limited here.

[0038] In some embodiments, a comparator circuit can be used to implement signal processing. The specific steps include: selecting a suitable comparator IC; connecting the output of the temperature detection subcircuit to one input of the comparator; setting a reference voltage source to the other input of the comparator as the temperature control threshold; and designing the comparator's output circuit to ensure that the correct high and low levels are output under different conditions. This is not limited here.

[0039] The second signal processing subcircuit has an input terminal commonly connected to an external power supply, an input terminal of the drive control subcircuit, and a control terminal of the drive control subcircuit, and an output terminal connected to ground. The second signal processing subcircuit is configured to, when the control terminal of the second signal processing subcircuit receives a high-level signal, connect the external power supply to ground via the second signal processing subcircuit, and enable the control terminal of the drive control subcircuit to receive a low-level signal. The second signal processing subcircuit is configured to, when the control terminal of the second signal processing subcircuit receives a low-level signal, prohibit the external power supply from being connected to ground via the second signal processing subcircuit, and enable the control terminal of the drive control subcircuit to receive a high-level signal.

[0040] In some embodiments, the second signal processing subcircuit controls the operating state of the drive control subcircuit based on a signal received from the first signal processing subcircuit. Upon receiving a high-level signal (indicating a normal temperature), the second signal processing subcircuit connects the external power supply to ground, placing the drive control subcircuit in an inactive state. Upon receiving a low-level signal (indicating a temperature exceeding a threshold), the second signal processing subcircuit disconnects the external power supply from ground, placing the drive control subcircuit in an active state.

[0041] In some specific embodiments, a transistor switching circuit can be used to implement signal processing. The specific steps include: selecting a transistor, designing a gate drive circuit for the transistor, and connecting it to the output of the first signal processing subcircuit; connecting the source of the transistor to ground, and the drain to the control terminal of the drive control subcircuit; this is not limited here.

[0042] In some specific embodiments, a relay circuit can be used to implement signal processing, including: selecting a relay; designing a relay drive circuit connected to the output of the first signal processing subcircuit; and connecting the normally open contact of the relay between an external power supply and a control terminal of the drive control subcircuit. This is not limited here.

[0043] The output end of the drive control subcircuit is connected to the control end of the first signal processing subcircuit and the external output end, and is used to prevent the external output end from outputting a signal when the control end of the drive control subcircuit receives a low-level signal; and to saturate and conduct the first signal processing subcircuit by outputting a high signal to the control end of the first signal processing subcircuit when the control end of the drive control subcircuit receives a high-level signal, and output a signal through the external output end.

[0044] In some embodiments, the drive control subcircuit determines whether to output a drive signal based on a control signal received from the second signal processing subcircuit. When a low-level signal is received (indicating a normal temperature), the drive control subcircuit does not output a signal, maintaining normal operation. When a high-level signal is received (indicating a temperature exceeding a threshold), the drive control subcircuit not only outputs a protection signal through the external output terminal but also simultaneously outputs a high-level signal to the control terminal of the first signal processing subcircuit, causing it to saturate and conduct.

[0045] In some specific embodiments, a transistor can be used to implement the drive control subcircuit. The specific steps include: selecting a transistor as the primary drive element; connecting the base (control terminal) of the transistor to the output terminal of the second signal processing subcircuit; connecting the emitter of the transistor to the next-stage circuit as the output terminal of the drive control subcircuit and to the control terminal of the first signal processing subcircuit; and connecting the collector of the transistor to a power supply.

[0046] In some specific embodiments, an operational amplifier circuit can be used to implement drive control. The specific steps include: selecting an operational amplifier, connecting the output of the second signal processing subcircuit to the non-inverting input terminal; setting a suitable reference voltage to the inverting input terminal; designing an output stage circuit, connecting it to the external output terminal and the control terminal of the first signal processing subcircuit; and adding a positive feedback network to achieve a self-locking function. This is not limited here.

[0047] As can be seen, the temperature detection subcircuit converts temperature information into a voltage signal that is negatively correlated with the external temperature. The first signal processing subcircuit performs temperature determination based on this voltage signal. When the temperature exceeds a preset threshold, the external power supply is connected to ground through the first signal processing subcircuit, causing the control terminal of the second signal processing subcircuit to receive a low-level signal. The second signal processing subcircuit prohibits the external power supply from connecting to ground through the second signal processing subcircuit, causing the control terminal of the drive control subcircuit to receive a high-level signal. The drive control subcircuit turns on the output signal and, by outputting a high signal to the control terminal of the first signal processing subcircuit, causes it to rapidly saturate and conduct. The high signal output by the drive control subcircuit causes the first signal processing subcircuit to rapidly saturate and conduct, achieving high-sensitivity turn-on. Furthermore, the turn-on process avoids linear region variations, thus avoiding potential instability.

[0048] In some embodiments, the circuit further comprises a first voltage divider filter subcircuit;

[0049] The output end of the temperature detection subcircuit is connected to the control end of the first signal processing subcircuit through the first voltage divider and filter subcircuit, and the first voltage divider and filter subcircuit is used to divide and filter the voltage between the output end of the temperature detection subcircuit and the control end of the first signal processing subcircuit.

[0050] In some embodiments, when the temperature detection subcircuit detects a temperature change and outputs a corresponding electrical signal, this signal may contain noise or have a voltage amplitude that is unsuitable for direct input to the first signal processing subcircuit. Therefore, a first voltage divider and filter subcircuit is placed between the two subcircuits. This divider reduces the voltage to an appropriate range and filters the signal to remove high-frequency noise. This processed signal is more stable and reliable, facilitating the normal operation and accurate processing of the first signal processing subcircuit.

[0051] In some specific embodiments, an RC low-pass filter combination can be used, and the specific steps include: selecting a resistor with a suitable resistance value and connecting one end of the resistor to the output end of the temperature detection sub-circuit; selecting a capacitor with a suitable capacitance and connecting one end of the capacitor to the output end of the temperature detection sub-circuit; adjusting the values ​​of the resistor and capacitor according to the required voltage division ratio and filtering effect, which are not limited here.

[0052] As can be seen, the voltage divider function allows for more flexible adjustment of the temperature detection range, adapting to different application scenarios and temperature requirements. Secondly, the filtering function effectively reduces noise interference in the circuit and improves the signal-to-noise ratio of the temperature signal. These two functions combined not only improve the accuracy of temperature detection but also enhance the circuit's resistance to environmental interference.

[0053] In some embodiments, the circuit further comprises a second voltage divider filter subcircuit;

[0054] The control terminal of the second signal processing subcircuit is connected to the external power supply through the second voltage divider and filter subcircuit, and the second voltage divider and filter subcircuit is used to divide and filter the voltage between the external power supply connection and the control terminal of the second signal processing subcircuit.

[0055] As can be seen, the voltage divider function allows for more precise setting of the temperature control threshold, enabling the voltage to operate normally over a wider range of power supply voltages. The filtering function effectively suppresses voltage fluctuations and noise interference that may be introduced by the external power supply, ensuring the stability of the control signal received by the second signal processing sub-circuit.

[0056] In some embodiments, the circuit further comprises a voltage stabilizing rectifier circuit;

[0057] The output end of the drive control circuit is connected to the external output end through a voltage-stabilizing rectifier circuit; the voltage-stabilizing rectifier circuit is used to output a signal to the external output end when the voltage at the output end of the drive control circuit is greater than a preset voltage-stabilizing threshold; and the voltage-stabilizing rectifier circuit is used to prohibit the external output end from outputting voltage in the reverse direction to the drive control circuit.

[0058] In some embodiments, when the drive control circuit generates an output signal, this signal first passes through a voltage-stabilizing rectifier circuit. The voltage-stabilizing rectifier circuit detects the voltage level of the input signal and only allows the signal to be transmitted to the external output terminal when the voltage exceeds a preset voltage-stabilizing threshold. This ensures that the output signal always remains within a stable voltage range, which is conducive to the normal operation of subsequent equipment. At the same time, the voltage-stabilizing rectifier circuit also has a unidirectional conduction characteristic, which only allows current to flow from the drive control circuit to the external output terminal, while prohibiting reverse current. This design can effectively protect the drive control circuit from interference from reverse voltage or current that may be generated by external circuits, thereby enhancing the reliability and safety of the entire circuit.

[0059] In some specific embodiments, a combination of a voltage regulator and a rectifier diode may be used. The specific steps include: selecting a voltage regulator and connecting its anode to the emitter of the drive control circuit; selecting a rectifier diode and connecting its anode to the cathode of the voltage regulator; and connecting the cathode of the rectifier diode to the external output terminal.

[0060] As can be seen, the voltage stabilization function ensures the stability of the output signal, providing a stable signal to the external output terminal even when the output of the drive control circuit fluctuates. Secondly, the rectification function prevents the external voltage from being reversely input into the drive control circuit, effectively protecting the internal circuit from external interference and potential damage.

[0061] See also Figure 2 , Figure 2 This is a schematic diagram of a circuit principle of a temperature control protection circuit in an embodiment of the present application. In some embodiments, the temperature control protection circuit is characterized by comprising: an NTC thermistor R2, a transistor Q1, a transistor Q3, and a MOS transistor Q2;

[0062] The external power supply is connected to the base of transistor Q3 through NTC thermistor R2;

[0063] The external power supply, the collector of the transistor Q3, and the gate of the MOS tube Q2 are connected together;

[0064] The emitter of transistor Q3 is grounded;

[0065] The drain of the MOS tube Q2 is connected to the external power supply, the base of the transistor Q1 and the collector of the transistor Q1;

[0066] The source of MOS tube Q2 is grounded;

[0067] The emitter of the transistor Q1 is connected to the base of the transistor Q3 and the external output terminal.

[0068] Thermistor R2 is a negative temperature coefficient (NTC) thermistor. Its primary function is to sense changes in ambient temperature. As the temperature rises, the resistance of thermistor R2 decreases, causing the current flowing through it to increase. This current change affects the base voltage of transistor Q3, which is connected to thermistor R2.

[0069] Transistor Q3 is an NPN transistor. Its base is connected to thermistor R2, its collector is connected to the external power supply and the gate of MOS transistor Q2, and its emitter is grounded. Transistor Q3's main function is to control its conduction state based on changes in the base voltage. When the base voltage rises to a certain level, transistor Q3 switches from the off state to the on state. After transistor Q3 turns on, its collector voltage drops rapidly from a high level to a low level. This voltage change directly affects the gate voltage of MOS transistor Q2.

[0070] MOS transistor Q2 is an N-channel enhancement mode MOS field effect transistor. Its gate is connected to the collector of transistor Q3, its drain is connected to the external power supply and the base and collector of transistor Q1, and its source is grounded. MOS transistor Q2's main function is to control its conduction state based on changes in the gate voltage, thereby affecting the base voltage of transistor Q1. When MOS transistor Q2 is turned off, its drain voltage rises from a low level to a high level, and this change affects the base voltage of transistor Q1.

[0071] Transistor Q1 is another NPN transistor. Its base and collector are connected to the drain of MOS transistor Q2, while its emitter is connected to the base of transistor Q3 and the external output. Transistor Q1's primary function is to control the signal at the external output. When MOS transistor Q2 turns off, causing the base voltage of Q1 to rise, transistor Q1 transitions from the off state to the on state. When transistor Q1 turns on, its collector voltage rapidly decreases, while its emitter voltage increases. This not only provides a signal to the external output but also provides additional current through the emitter to the base of transistor Q3, forming positive feedback.

[0072] In some embodiments, resistor R8 and capacitor C2;

[0073] The NTC thermistor R2, one end of the resistor R8, one end of the capacitor C2, and the base of the transistor Q3 are connected together;

[0074] The other end of the resistor R8 and the other end of the capacitor C2 are grounded.

[0075] One end of resistor R8 is connected to NTC thermistor R2, one end of capacitor C2, and the base of transistor Q3. The other end is grounded. Resistor R8 forms a voltage divider with NTC thermistor R2, providing a suitable bias voltage for the base of transistor Q3. Resistor R8 also limits the current flowing through NTC thermistor R2, preventing self-heating from affecting temperature measurement. Resistor R8 also provides a discharge path for capacitor C2.

[0076] One end of capacitor C2 is connected to NTC thermistor R2, one end of resistor R8, and the base of transistor Q3. The other end is grounded. Capacitor C2's primary functions are filtering and delay. It suppresses high-frequency noise in the temperature detection circuit, stabilizing the base voltage of transistor Q3. Furthermore, capacitor C2 introduces a time constant, slowing the change in the base voltage of transistor Q3 and preventing false triggering due to transient temperature fluctuations.

[0077] Resistor R8 and capacitor C2 together form an RC low-pass filter circuit.

[0078] In some embodiments, the circuit further includes: a resistor R7 and a capacitor C1;

[0079] An external power supply, a collector of the transistor Q3, a gate of the MOS transistor Q2, one end of the resistor R7 and one end of the capacitor C1 are connected together;

[0080] The other ends of the resistor R7 and the capacitor C1 are grounded.

[0081] One end of resistor R7 is connected to an external power supply, the collector of transistor Q3, the gate of MOS transistor Q2, and one end of capacitor C1. The other end is grounded. Resistor R7 provides a stable bias voltage for the gate of MOS transistor Q2 and also acts as a load resistor for the collector of transistor Q3. When transistor Q3 is off, resistor R7 pulls up the gate of MOS transistor Q2, keeping it on. When transistor Q3 is on, resistor R7 and transistor Q3 form a voltage divider circuit, reducing the gate voltage of MOS transistor Q2.

[0082] One end of capacitor C1 is connected to the external power supply, the collector of transistor Q3, the gate of MOS transistor Q2, and one end of resistor R7. The other end is grounded. Capacitor C1's primary function is to filter and stabilize the circuit. It suppresses high-frequency noise in the circuit and prevents drastic fluctuations in the gate voltage of MOS transistor Q2.

[0083] Resistor R7 and capacitor C1 together form an RC low-pass filter circuit.

[0084] In some embodiments, a voltage regulator diode D1, a rectifier diode D2, and a resistor R9;

[0085] The emitter of transistor Q1 is connected to the external output terminal through voltage regulator diode D1 and rectifier diode D2;

[0086] The emitter of the transistor Q1 is connected to the base of the transistor Q3 via the resistor R9.

[0087] The anode of Zener diode D1 is connected to the emitter of transistor Q1, and its cathode is connected to the anode of rectifier diode D2. Zener diode D1's primary function is to limit the maximum output voltage. When transistor Q1 is conducting, if the emitter voltage exceeds the breakdown voltage of Zener diode D1, Zener diode D1 turns on, clamping the excess voltage to its regulated value. This protects subsequent circuits from damage caused by excessive voltage. Zener diode D1 also provides a stable reference voltage, making the output signal more reliable.

[0088] The anode of rectifier diode D2 is connected to the cathode of Zener diode D1, which is then connected to the external output terminal. Rectifier diode D2's primary function is to prevent reverse voltage from the external output terminal from flowing back into the circuit. It ensures that current can only flow from within the circuit to the external output terminal, and not from the external output terminal back into the circuit. This unidirectional conduction effectively isolates the circuit from external interference or load changes, improving its stability and reliability.

[0089] One end of resistor R9 is connected to the emitter of transistor Q1, and the other end is connected to the base of transistor Q3. The main function of resistor R9 is to provide a positive feedback path and limit the magnitude of the feedback current.

[0090] In some embodiments, the circuit further comprises: a resistor R2;

[0091] NTC thermistor R2 is connected to the base of transistor Q3 through resistor R2;

[0092] Resistor R2 can limit the current flowing through the NTC thermistor R2, and to a certain extent protect the base of transistor Q3, preventing excessive current from flowing directly into the base.

[0093] In some embodiments, resistor R3 and resistor R5;

[0094] The external power supply is connected to the base of transistor Q1 and the collector of transistor Q1 through resistor R3;

[0095] The external power supply is connected to the drain of the MOS tube Q2 through the resistor R3 and the resistor R5.

[0096] Resistor R3 limits the current flowing from the external power supply to the base of transistor Q1. This helps control the bias state of transistor Q1 and prevents excessive base current from damaging the transistor.

[0097] Resistor R5 limits the current flowing from the external power supply to the drain of MOS transistor Q2, which helps control the working state of MOS transistor Q2 and prevent excessive drain current.

Claims

1. Temperature control protection circuit, characterized in that, include: a temperature detection subcircuit, a first signal processing subcircuit, a second signal processing subcircuit, and a drive control subcircuit; The input end of the temperature detection subcircuit is connected to the external power supply, and the output end is connected to the control end of the first signal processing subcircuit, and is used to control the voltage between the external power supply and the control end of the first signal processing subcircuit, wherein the voltage is negatively correlated with the external temperature; The input terminal of the first signal processing subcircuit is commonly connected to the control terminal of the second signal processing subcircuit and the external power supply, and the output terminal is connected to the ground; when the voltage at the control terminal of the first signal processing subcircuit is not greater than a preset temperature control threshold, the external power supply is prohibited from being connected to the ground through the first signal processing subcircuit, so that the control terminal of the second signal processing subcircuit receives a high-level signal; when the voltage at the control terminal of the first signal processing subcircuit is greater than the preset threshold, the external power supply is allowed to be connected to the ground through the first signal processing subcircuit, so that the control terminal of the second signal processing subcircuit receives a low-level signal; The second signal processing sub-circuit has an input terminal commonly connected to the external power supply, the input terminal of the drive control sub-circuit, and the control terminal of the drive control sub-circuit, and an output terminal connected to ground. The second signal processing sub-circuit is configured to, when the control terminal of the second signal processing sub-circuit receives a high-level signal, connect the external power supply to ground via the second signal processing sub-circuit, and enable the control terminal of the drive control sub-circuit to receive a low-level signal. The second signal processing sub-circuit is configured to, when the control terminal of the second signal processing sub-circuit receives a low-level signal, prohibit the external power supply from being connected to ground via the second signal processing sub-circuit, and enable the control terminal of the drive control sub-circuit to receive a high-level signal. The output end of the drive control subcircuit is connected to the control end and the external output end of the first signal processing subcircuit, and is used for not outputting a signal from the external output end when the control end of the drive control subcircuit receives a low-level signal; and for saturating and conducting the control end of the first signal processing subcircuit by outputting a high signal to the control end of the first signal processing subcircuit when the control end of the drive control subcircuit receives a high-level signal, and outputting a signal through the external output end.

2. The circuit according to claim 1, wherein: The circuit further includes a first voltage divider filter subcircuit; The output end of the temperature detection subcircuit is connected to the control end of the first signal processing subcircuit through the first voltage divider and filter subcircuit, and the first voltage divider and filter subcircuit is used to divide and filter the voltage between the output end of the temperature detection subcircuit and the control end of the first signal processing subcircuit.

3. The circuit according to claim 1, wherein: The circuit further includes a second voltage divider filter subcircuit; The control end of the second signal processing subcircuit is connected to the external power supply through the second voltage divider and filter subcircuit, and the second voltage divider and filter subcircuit is used to divide and filter the voltage between the external power supply connection and the control end of the second signal processing subcircuit.

4. The circuit according to claim 1, wherein: The circuit also includes a voltage-stabilizing rectifier circuit; The output end of the drive control subcircuit is connected to the external output end through the voltage stabilizing rectifier subcircuit; the voltage stabilizing rectifier subcircuit is used to output a signal to the external output end when the voltage at the output end of the drive control subcircuit is greater than a preset voltage stabilization threshold; and the voltage stabilizing rectifier subcircuit is used to prohibit the external output end from outputting voltage in the reverse direction to the drive control subcircuit.

5. Temperature control protection circuit, characterized in that, include: NTC thermistor R2, transistor Q1, transistor Q3, MOS tube Q2; The external power supply is connected to the base of the transistor Q3 through the NTC thermistor R2; The external power supply, the collector of the transistor Q3, and the gate of the MOS transistor Q2 are connected together; The emitter of the transistor Q3 is grounded; The drain of the MOS transistor Q2 is commonly connected to the external power supply, the base of the transistor Q1, and the collector of the transistor Q1; The source of the MOS tube Q2 is grounded; The emitter of the transistor Q1 is connected to the base of the transistor Q3 and the external output terminal.

6. The circuit according to claim 5, characterized in that The circuit further comprises: a resistor R8 and a capacitor C2; The NTC thermistor R2, one end of the resistor R8, one end of the capacitor C2, and the base of the transistor Q3 are connected together; The other end of the resistor R8 and the other end of the capacitor C2 are grounded.

7. The circuit according to claim 5, characterized in that The circuit further includes: a resistor R7 and a capacitor C1; The external power supply, the collector of the transistor Q3, the gate of the MOS transistor Q2, one end of the resistor R7 and one end of the capacitor C1 are connected together; The other ends of the resistor R7 and the capacitor C1 are grounded.

8. The circuit according to claim 5, characterized in that The circuit also includes: a voltage regulator tube D1, a rectifier diode D2 and a resistor R9; The emitter of the transistor Q1 is connected to the external output terminal through the voltage regulator diode D1 and the rectifier diode D2; The emitter of the transistor Q1 is connected to the base of the transistor Q3 through the resistor R9.

9. The circuit according to claim 5, characterized in that The circuit further includes: a resistor R2; The NTC thermistor R2 is connected to the base of the transistor Q3 via the resistor R2.

10. The circuit according to claim 5, characterized in that The circuit further includes: a resistor R3 and a resistor R5; The external power supply is connected to the base of the transistor Q1 and the collector of the transistor Q1 through the resistor R3; The external power supply is connected to the drain of the MOS transistor Q2 through the resistor R3 and the resistor R5.

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