Temperature control protection circuit

Abstract

The present application provides a temperature control protection circuit, which relates to the field of circuit protection technology. The temperature detection subcircuit converts the temperature information into a voltage signal that is negatively correlated with the external temperature, and the first signal processing subcircuit makes a temperature judgment based on this voltage signal. When the temperature exceeds the preset threshold, the external power supply is connected to the external low level through the first signal processing subcircuit, so that the control end of the second signal processing subcircuit receives a low level signal; the second signal processing subcircuit prohibits the external power supply from connecting to the external low level through the second signal processing subcircuit, so that the control end of the drive control subcircuit receives a high level signal; a high-sensitivity opening is achieved, and at the same time, there is no problem of linear region change during the opening process, avoiding possible unstable states.

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 getting higher and higher. In various electronic products, power management chips need to have multiple protection functions, among which over-temperature protection is one of the important functions to ensure the safe operation of equipment. Over-temperature protection can take timely measures when the chip temperature is too high to prevent the chip from being damaged due to overheating, thereby improving the reliability and service life of the product.

[0003] At present, the common methods for implementing over-temperature protection include the solution of using a single-chip microcomputer plus NTC (negative temperature coefficient thermistor) and the solution of using a comparator. In the solution of single-chip microcomputer plus NTC, the voltage value of NTC is read by the analog-to-digital converter (ADC) of the single-chip microcomputer to judge the temperature. This method sets the temperature threshold through programming, and triggers the protection mechanism when the temperature exceeds the threshold. The solution using a comparator compares the voltage value of NTC with the preset reference voltage through the comparator. When the temperature exceeds the set threshold, the comparator outputs a trigger signal to achieve over-temperature protection.

[0004] However, these related technologies have some problems in practical applications. For the solution of single-chip microcomputer plus NTC, due to the different ADC precision of single-chip microcomputers with different bit numbers, the accuracy of temperature detection may vary greatly. 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. Summary of the invention

[0005] The present application provides a temperature control protection circuit for improving 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 external low level; 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 connecting to the external low level 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 connect to the external low level 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 driving control subcircuit is connected to the control end of the first signal processing subcircuit and the control end of the driving control subcircuit, and the output end is connected to the external low level, and is used for, when the control end of the second signal processing subcircuit receives a high level signal, enabling the external power supply to connect to the external low level through the second signal processing subcircuit, so that the control end of the driving control subcircuit receives a low level signal, and is used for, when the control end of the second signal processing subcircuit receives a low level signal, prohibiting the external power supply from connecting to the external low level through the second signal processing subcircuit, so that the control end of the driving control subcircuit receives a high level signal; the output end of the driving 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 driving control subcircuit receives a low level signal, the external output end does not output a signal; when the control end of the driving control subcircuit receives a high level signal, the control end of the first signal processing subcircuit is saturated and turned on by outputting a high signal to the control end, and outputs a signal through the external output end.

[0008] By adopting the above technical solution, the temperature detection subcircuit converts the temperature information into a voltage signal that is negatively correlated with the external temperature, and the first signal processing subcircuit makes a temperature judgment based on this voltage signal. When the temperature exceeds the preset threshold, the external power supply is connected to the external low level through the first signal processing subcircuit, so that the control end of the second signal processing subcircuit receives a low level signal; the second signal processing subcircuit prohibits the external power supply from connecting to the external low level through the second signal processing subcircuit, so that the control end of the drive control subcircuit receives a high level signal; the drive control subcircuit turns on the output signal, and by outputting a high signal to the control end of the first signal processing subcircuit, it is quickly saturated and turned on; the high signal output by the drive control subcircuit causes the first signal processing subcircuit to quickly saturate and turn on, achieving high-sensitivity opening. At the same time, there is no linear region change problem during the opening process, avoiding possible unstable states.

[0009] In combination with some embodiments of the first aspect, in some embodiments, the circuit also includes a first voltage divider and 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 and filter sub-circuit, and the first voltage divider and 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 the above technical solution, the voltage division function allows for more flexible adjustment of the temperature detection range, which can adapt to different application scenarios and temperature requirements. Secondly, the filtering function effectively reduces the noise interference in the circuit and improves the signal-to-noise ratio of the temperature signal. The combination of these two functions not only improves the accuracy of temperature detection, but also enhances 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 adopting the above technical solution, the voltage division function allows the temperature control threshold to be set more accurately, so that the voltage can work normally within a wider power supply voltage range. The filtering function effectively suppresses the voltage fluctuation and noise interference that may be caused by the external power supply, ensuring the stability of the control signal received by the second signal processing subcircuit.

[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 driving 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 driving 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 a voltage in the reverse direction to the driving control circuit.

[0014] By adopting the above technical solutions, the voltage stabilization function ensures the stability of the output signal, and can provide 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 to 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 tube 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 tube Q2 are connected together; the emitter of the transistor Q3 is grounded; 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; 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 end.

[0016] In combination with some embodiments of the second aspect, in some embodiments, the circuit also 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 also includes: a resistor R7 and a capacitor C1; an external power supply, a collector of the transistor Q3, a gate of the MOS tube Q2, one end of the resistor R7 and one end of the capacitor C1 are connected together; 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 also 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 also 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 tube Q2 through the resistor R3 and the resistor R5.

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

[0022] 1. The temperature detection subcircuit converts the temperature information into a voltage signal that is negatively correlated with the external temperature, and the first signal processing subcircuit makes a temperature judgment based on this voltage signal. When the temperature exceeds the preset threshold, the external power supply connects to the external low level through the first signal processing subcircuit, so that the control end of the second signal processing subcircuit receives a low level signal; the second signal processing subcircuit prohibits the external power supply from connecting to the external low level through the second signal processing subcircuit, so that the control end of the drive control subcircuit receives a high level signal; the drive control subcircuit turns on the output signal, and by outputting a high signal to the control end of the first signal processing subcircuit, it quickly saturates and conducts; the high signal output by the drive control subcircuit causes the first signal processing subcircuit to quickly saturate and conduct, achieving high-sensitivity opening. At the same time, there is no linear region change problem during the opening process, avoiding possible unstable states.

[0023] 2. The voltage division function allows for more flexible adjustment of the temperature detection range, which can adapt to different application scenarios and temperature requirements. Secondly, the filtering function effectively reduces the noise interference in the circuit and improves the signal-to-noise ratio of the temperature signal. The combination of these two functions not only improves the accuracy of temperature detection, but also enhances the circuit's resistance to environmental interference.

[0024] 3. The voltage division function allows the temperature control threshold to be set more accurately, so that the voltage can work normally within a wider range of power supply voltage. The filtering function effectively suppresses the voltage fluctuation and noise interference that may be caused by the external power supply, ensuring the stability of the control signal received by the second signal processing subcircuit. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0027] The terms used in the following embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to be used as limitations to the present application. As used in the specification and appended claims of the present application, the singular expressions "one", "a kind of", "said", "above", "the" and "this" are intended to also include plural expressions, unless there is a clear indication to the contrary in the context. It should also be understood that the term "and / or" used in the present application refers to and includes any or all possible combinations of one or more listed items.

[0028] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as suggesting or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features, and in the description of the embodiments of the present application, unless otherwise specified, "plurality" means two or more.

[0029] See also Figure 1 , Figure 1 It 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 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;

[0031] External power supply refers to the power supply that provides energy for 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 obtains the working voltage from the external power supply through its input terminal, and then generates a voltage signal inversely proportional to the temperature at its output terminal according to the change of the ambient temperature. This voltage signal is sent to the control terminal of the first signal processing subcircuit as an input for subsequent processing. The temperature detection subcircuit actually plays the role of converting the physical quantity of temperature into the electrical quantity of voltage, providing the initial temperature information for the entire temperature control circuit.

[0033] In some specific embodiments, NTC (negative temperature coefficient) thermistors 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; adjusting the resistance value of the fixed resistor to obtain 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. The specific steps include: selecting a temperature sensor IC, connecting the output end of the sensor 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 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 external low level; when the voltage of 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 connecting to the external low level 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 of the control end of the first signal processing subcircuit is greater than the preset threshold, the external power supply is allowed to connect to the external low level through the first signal processing subcircuit, so that the control end 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 the preset temperature control threshold. When the temperature is lower than the threshold, the circuit maintains a normal working state and outputs a high-level signal; when the temperature exceeds the threshold, the circuit switches to a protection state 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 end) of the transistor to the output end of the temperature detection subcircuit so that the temperature signal controls the switching state of the transistor; connecting the collector (input end) of the transistor to an external power supply through a suitable pull-up resistor (such as 10kΩ). This configuration ensures that the collector maintains a high level when the transistor is turned off; directly grounding the emitter (output end) of the transistor; connecting the control end of the second signal processing subcircuit to the collector of the transistor. In this way, the second signal processing subcircuit can detect the level change of the collector; through this design, when the temperature detection subcircuit outputs a low level (corresponding to a low temperature), the transistor is cut off and its collector presents a high level; when the temperature detection subcircuit outputs a high level (corresponding to a high temperature), the transistor is turned on and its collector presents a low level. In this way, the control end of the second signal processing subcircuit can present high and low levels related to temperature through the switching state of the transistor, thereby realizing the processing and conversion of 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 connected to the other input of the comparator as a temperature control threshold; designing the output circuit of the comparator to ensure that the correct high and low levels are output in different situations; this is not limited here.

[0039] The input end of the second signal processing subcircuit is commonly connected to the external power supply, the input end of the drive control subcircuit, and the control end of the drive control subcircuit, and the output end is connected to the external low level, and is used to make the external power supply connect to the external low level through the second signal processing subcircuit when the control end of the second signal processing subcircuit receives a high level signal, so that the control end of the drive control subcircuit receives a low level signal, and is used to prohibit the external power supply from connecting to the external low level through the second signal processing subcircuit when the control end of the second signal processing subcircuit receives a low level signal, so that the control end of the drive control subcircuit receives a high level signal;

[0040] In some embodiments, the second signal processing subcircuit controls the working state of the drive control subcircuit according to the signal received from the first signal processing subcircuit. When a high-level signal (indicating that the temperature is normal) is received, the second signal processing subcircuit connects the external power supply to the external low level, so that the drive control subcircuit enters a non-working state. When a low-level signal (indicating that the temperature exceeds a threshold) is received, the second signal processing subcircuit cuts off the connection between the external power supply and the external low level, so that the drive control subcircuit enters a working state.

[0041] In some specific embodiments, a transistor switch circuit can be used to implement signal processing. The specific steps include: selecting a transistor, designing a gate drive circuit of the transistor, and connecting it to the output of the first signal processing subcircuit; connecting the source of the transistor to an external low level, and connecting 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 drive circuit of the relay, connected to the output of the first signal processing subcircuit; 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 driving control subcircuit is connected to the control end of the first signal processing subcircuit and the external output end, and is used for not outputting a signal at the external output end when the control end of the driving control subcircuit receives a low-level signal; when the control end of the driving control subcircuit receives a high-level signal, the control end of the first signal processing subcircuit is saturated and turned on by outputting a high signal, and outputting a signal through the external output end.

[0044] In some embodiments, the drive control subcircuit determines whether to output the drive signal according to the control signal received from the second signal processing subcircuit. When a low-level signal is received (indicating that the temperature is normal), the drive control subcircuit does not output a signal, and the circuit maintains a normal working state. When a high-level signal is received (indicating that the temperature exceeds the 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 be saturated and turned on.

[0045] In some specific embodiments, a transistor can be used to implement the drive control subcircuit, and the specific steps include: selecting a transistor as the main 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 level circuit as the output terminal of the drive control subcircuit, and connected to the control terminal of the first signal processing subcircuit; the collector of the transistor is connected to the 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; adding a positive feedback network to realize a self-locking function, which is not limited here.

[0047] It can be seen that the temperature detection subcircuit converts the temperature information into a voltage signal that is negatively correlated with the external temperature, and the first signal processing subcircuit makes a temperature judgment based on this voltage signal. When the temperature exceeds the preset threshold, the external power supply is connected to the external low level through the first signal processing subcircuit, so that the control end of the second signal processing subcircuit receives a low level signal; the second signal processing subcircuit prohibits the external power supply from connecting to the external low level through the second signal processing subcircuit, so that the control end of the drive control subcircuit receives a high level signal; the drive control subcircuit turns on the output signal, and by outputting a high signal to the control end of the first signal processing subcircuit, it quickly saturates and conducts; the high signal output by the drive control subcircuit causes the first signal processing subcircuit to quickly saturate and conduct, achieving high-sensitivity opening. At the same time, there is no linear region change problem during the opening process, avoiding possible unstable states.

[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 temperature changes and outputs a corresponding electrical signal, this signal may contain noise or the voltage amplitude is not suitable for direct input to the first signal processing subcircuit. Therefore, the first voltage divider and filter subcircuit is placed between the two, and the voltage is reduced to a suitable range through voltage division, and the high-frequency noise components in the signal are removed through filtering; the processed signal is more stable and reliable, which is conducive to 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 subcircuit; selecting a capacitor with a suitable capacitance and connecting one end of the capacitor to the output end of the temperature detection subcircuit; adjusting the values ​​of the resistor and the capacitor according to the required voltage division ratio and filtering effect, which are not limited here.

[0052] It can be seen that the voltage division function allows for more flexible adjustment of the temperature detection range, which can adapt to different application scenarios and temperature requirements. Secondly, the filtering function effectively reduces the noise interference in the circuit and improves the signal-to-noise ratio of the temperature signal. The combination of these two functions not only improves the accuracy of temperature detection, but also enhances the circuit's resistance to environmental interference.

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

[0054] The control end of the second signal processing subcircuit is connected to the external power supply through the second voltage dividing and filtering subcircuit, and the second voltage dividing and filtering 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.

[0055] It can be seen that the voltage division function allows the temperature control threshold to be set more accurately, so that the voltage can work normally within a wider power supply voltage range. The filtering function effectively suppresses the voltage fluctuation and noise interference that may be caused by the external power supply, ensuring the stability of the control signal received by the second signal processing subcircuit.

[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, the signal first passes through the voltage stabilizing rectifier circuit. The voltage stabilizing rectifier circuit detects the voltage level of the input signal, and only when the voltage exceeds the preset voltage stabilizing threshold value, the signal is allowed to be transmitted to the external output terminal. 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 the characteristic of unidirectional conduction, which only allows current to flow from the drive control circuit to the external output terminal, and prohibits reverse current. This design can effectively protect the drive control circuit from the interference of reverse voltage or current that may be generated by the external circuit, and enhance the reliability and safety of the entire circuit.

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

[0060] It can be seen that the voltage stabilization function ensures the stability of the output signal, and can provide 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 to the drive control circuit, effectively protecting the internal circuit from external interference and potential damage.

[0061] See also Figure 2 , Figure 2 It is a circuit principle diagram of the temperature control protection circuit in the embodiment of the present application. In some embodiments, the temperature control protection circuit is characterized by comprising: NTC thermistor R2, transistor Q1, transistor Q3, MOS tube 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. The main function of thermistor R2 is to sense changes in ambient temperature. When the temperature rises, the resistance value of thermistor R2 decreases, causing the current flowing through thermistor R2 to increase. This current change affects the base voltage of transistor Q3 connected to thermistor R2.

[0069] Transistor Q3 is an NPN transistor. The base of transistor Q3 is connected to thermistor R2, the collector is connected to the external power supply and the gate of MOS tube Q2, and the emitter is grounded. The main function of transistor Q3 is to control its conduction state according to the change of base voltage. When the base voltage rises to a certain level, transistor Q3 will change from cut-off state to conduction state. After transistor Q3 is turned on, its collector voltage drops rapidly from high level to low level. This voltage change will directly affect the gate voltage of MOS tube Q2.

[0070] MOS tube Q2 is an N-channel enhancement type MOS field effect tube. The gate of MOS tube Q2 is connected to the collector of transistor Q3, the drain is connected to the external power supply and the base and collector of transistor Q1, and the source is grounded. The main function of MOS tube Q2 is to control its conduction state according to the change of gate voltage, thereby affecting the base voltage of transistor Q1. After MOS tube Q2 is turned off, its drain voltage will increase from low level to high level, and this change will affect the base voltage of transistor Q1.

[0071] Transistor Q1 is another NPN transistor. The base and collector of transistor Q1 are connected to the drain of MOS tube Q2, and the emitter is connected to the base of transistor Q3 and the external output terminal. The main function of transistor Q1 is to control the signal at the external output terminal. When MOS tube Q2 is cut off and the base voltage of Q1 increases, transistor Q1 will change from the cut-off state to the on state. After transistor Q1 is turned on, its collector voltage drops rapidly and the emitter voltage increases, which not only provides a signal to the external output terminal, but also provides additional current to the base of transistor Q3 through the emitter, 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, and the other end is grounded. The main function of resistor R8 is to form a voltage divider circuit with NTC thermistor R2 to provide a suitable bias voltage for the base of transistor Q3. Resistor R8 can also limit the current flowing through NTC thermistor R2 to prevent the self-heating effect from affecting the temperature measurement. At the same time, 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, and the other end is grounded. The main function of capacitor C2 is filtering and delay. It can suppress high-frequency noise in the temperature detection circuit and make the base voltage of transistor Q3 more stable. In addition, capacitor C2 can also introduce a certain time constant to slow down the change speed of the base voltage of transistor Q3 and prevent the circuit from being triggered by mistake due to instantaneous 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 source, a collector of the transistor Q3, a gate of the MOS tube 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 the resistor R7 is connected to the external power supply, the collector of the transistor Q3, the gate of the MOS transistor Q2 and one end of the capacitor C1, and the other end is grounded. The main function of the resistor R7 is to provide a stable bias voltage for the gate of the MOS transistor Q2, and also serve as a load resistor for the collector of the transistor Q3. When the transistor Q3 is in the cut-off state, the resistor R7 pulls up the gate of the MOS transistor Q2 to keep the MOS transistor Q2 turned on. When the transistor Q3 is turned on, the resistor R7 forms a voltage divider circuit with the transistor Q3 to reduce the gate voltage of the 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 tube Q2 and one end of resistor R7, and the other end is grounded. The main function of capacitor C1 is to filter and stabilize the circuit. It can suppress high-frequency noise in the circuit and prevent the gate voltage of MOS tube Q2 from fluctuating violently.

[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 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 the voltage regulator D1 is connected to the emitter of the transistor Q1, and the cathode is connected to the anode of the rectifier diode D2. The main function of the voltage regulator D1 is to limit the maximum value of the output voltage. When the transistor Q1 is turned on, if the emitter voltage exceeds the breakdown voltage of the voltage regulator D1, the voltage regulator D1 will be turned on and clamp the excess voltage to its voltage regulation value. This can protect the subsequent circuit from being damaged by excessive voltage. The voltage regulator D1 can also provide a stable reference voltage to make the output signal more reliable.

[0088] The anode of the rectifier diode D2 is connected to the cathode of the voltage regulator tube D1, and the cathode is connected to the external output terminal. The main function of the rectifier diode D2 is to prevent the voltage at the external output terminal from being reversely injected into the circuit. It ensures that the current can only flow from the inside of the circuit to the external output terminal, but cannot flow back from the external output terminal to the circuit. This unidirectional conductive characteristic can effectively isolate the external circuit, prevent external interference or load changes from affecting this circuit, and improve the stability and reliability of the circuit.

[0089] One end of the resistor R9 is connected to the emitter of the transistor Q1, and the other end is connected to the base of the transistor Q3. The main function of the resistor R9 is to provide a positive feedback path and limit the size 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] The resistor R2 can limit the current flowing through the NTC thermistor R2, and to a certain extent protect the base of the transistor Q3, preventing excessive current from directly flowing 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 source 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 tube Q2, which helps to control the working state of MOS tube 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 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 an external low level; when the voltage of the control end of the first signal processing subcircuit is not greater than a preset temperature control threshold, the external power supply is prohibited from connecting to the external low level 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 of the control end of the first signal processing subcircuit is greater than the preset temperature control threshold, the external power supply is allowed to connect to the external low level 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 commonly connected to the external power supply, the input end of the drive control subcircuit, and the control end of the drive control subcircuit, and the output end is connected to the external low level, and is used to enable the external power supply to connect to the external low level through the second signal processing subcircuit when the control end of the second signal processing subcircuit receives a high level signal, so that the control end of the drive control subcircuit receives a low level signal, and is used to prohibit the external power supply from connecting to the external low level through the second signal processing subcircuit when the control end of the second signal processing subcircuit receives a low level signal, 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 and the external output end of the first signal processing subcircuit, and is used for not outputting a signal at 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; Including: 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 tube 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.

2. The circuit according to claim 1, characterized in that The circuit also includes a first voltage-dividing 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, characterized in that The circuit also includes a second voltage-dividing filter subcircuit; The control end of the second signal processing subcircuit is connected to the external power supply through the second voltage dividing and filtering subcircuit, and the second voltage dividing and filtering 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, characterized in that 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 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 subcircuit 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 subcircuit.

5. The circuit according to claim 1, characterized in that The circuit also 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.

6. The circuit according to claim 1, characterized in that The circuit also 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.

7. The circuit according to claim 1, 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 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.

8. The circuit according to claim 1, 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.

9. The circuit according to claim 1, 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 source is connected to the drain of the MOS tube Q2 through the resistor R3 and the resistor R5.

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