CN114323320A - Temperature detection circuit and method and household appliance - Google Patents

Abstract

The application provides a temperature detection circuit and method and a household appliance. The temperature detection circuit includes: the circuit comprises a sampling circuit, a reference voltage circuit and a control circuit; the sampling circuit is connected with a sampling port of the control circuit; the reference voltage circuit is connected with a reference voltage input port of the control circuit; the sampling circuit is used for converting the temperature to be measured into a voltage signal to be measured; the reference voltage circuit is used for providing external reference voltage for a sampling port of the control circuit, and the external reference voltage is smaller than the internal reference voltage of the control circuit; the control circuit is used for determining the temperature to be detected according to the external reference voltage and the voltage signal to be detected, so that the accuracy of a detection result is improved, and the cost is reduced.

Description

Temperature detection circuit and method and household appliance

Technical Field

The embodiment of the application relates to the technical field of household appliances, in particular to a temperature detection circuit and method and a household appliance.

Background

Household appliances such as induction cookers, electric kettles, etc. which are used by people in daily life need to be detected in the use process. In household appliances, a sampling circuit is generally used to convert the temperature into an electrical signal, so as to determine a temperature value according to the electrical signal.

In the related art, a temperature detection circuit of a home appliance generally amplifies a signal collected by a sampling circuit by using an operational amplifier, and then inputs the amplified signal to a controller of the home appliance, and the controller determines a temperature value according to the amplified electric signal. Due to the influence of factors such as offset current and offset voltage of the operational amplifier, the accuracy of the temperature detection circuit using the operational amplifier is poor, and the cost of the operational amplifier is high.

Disclosure of Invention

The embodiment of the application provides a temperature detection circuit, a temperature detection method and a household appliance, so that the accuracy of the temperature detection circuit is improved, and the cost is reduced.

In a first aspect, the present application provides a temperature detection circuit, comprising: the circuit comprises a sampling circuit, a reference voltage circuit and a control circuit;

the sampling circuit is connected with a sampling port of the control circuit; the reference voltage circuit is connected with a reference voltage input port of the control circuit;

the sampling circuit is used for converting the temperature to be measured into a voltage signal to be measured;

the reference voltage circuit is used for providing an external reference voltage for a sampling port of the control circuit, and the external reference voltage is smaller than the internal reference voltage of the control circuit;

the control circuit is used for determining the temperature to be measured according to the external reference voltage and the voltage signal to be measured.

The temperature detection circuit directly obtains a voltage signal of the sampling circuit by using the control circuit, simultaneously adopts external reference voltage as sampling reference voltage, and the external reference voltage is smaller than the internal reference voltage of the control circuit, thereby not needing to use an operational amplifier, realizing accurate temperature detection, avoiding the problems of inaccurate result, higher cost and the like caused by the operational amplifier, not needing to carry out additional calibration, reducing the complexity of the circuit, also reducing the software compiling difficulty of the control circuit, and improving the detection precision by reducing the external reference voltage.

In one possible implementation, the sampling circuit includes a thermocouple;

the positive pole of the thermocouple is connected with the sampling port of the control circuit, and the negative pole of the thermocouple is grounded.

The temperature detection circuit provides lower external reference voltage based on the voltage range of the thermocouple, so that a detection result with higher precision can be obtained under the condition of lower external reference voltage, and the condition that the external reference voltage is too small to cause abnormal sampling is avoided.

In a possible implementation manner, the sampling port of the control circuit is connected with one input/output port of the control circuit through a first resistor;

the control circuit is used for controlling the input/output port to output high level and determining the connection state between the sampling circuit and the sampling port according to the sampling value of the sampling port, wherein the connection state comprises connection or disconnection;

the control circuit is used for controlling the input/output port to be in an input state when the connection state between the sampling circuit and the sampling port is determined to be connection, and determining the temperature to be measured according to the external reference voltage and the voltage signal to be measured.

The temperature detection circuit utilizes the input/output port of the control circuit to output high level to detect the connection state between the sampling circuit and the sampling port, thereby avoiding temperature detection result error under the condition of open circuit, simultaneously having simple circuit structure, not increasing circuit cost, simple control method and judgment method and lower software compiling difficulty.

In a possible implementation, the first resistor is a pull-up resistor in the sampling port or a pull-up resistor in the input/output port.

The adoption of the pull-up resistor in the input/output port or the sampling port can simplify the structure of the temperature detection circuit and further reduce the circuit cost.

In a possible implementation manner, when the input/output port outputs a high level, the control circuit is configured to determine that the connection state between the sampling circuit and the sampling port is disconnected when a difference between a sampled value of the sampling port and an internal reference voltage of the control circuit is less than or equal to a preset value, or the control circuit is configured to determine that the connection state between the sampling circuit and the sampling port is connected when a difference between a sampled value of the sampling port and an internal reference voltage of the control circuit is greater than a preset value.

In one possible implementation, the reference voltage circuit includes a voltage divider circuit and/or a voltage regulator circuit.

In one possible implementation, the reference voltage circuit includes a voltage divider circuit; the voltage dividing circuit includes: a second resistor and a third resistor;

the first end of the second resistor is connected with a power supply; the second end of the second resistor is respectively connected with the first end of the third resistor and the reference voltage input port; and the second end of the third resistor is grounded.

The temperature detection circuit adopts a voltage division circuit to provide lower external reference voltage required by the control circuit.

In one possible implementation, the reference voltage circuit includes a voltage regulator circuit; the voltage stabilizing circuit comprises: a voltage regulator and a fourth resistor;

the first end of the fourth resistor and the reference voltage input port are respectively connected with the first end of the voltage-stabilizing source, the second end of the voltage-stabilizing source is grounded, and the third end of the voltage-stabilizing source is connected with the first end of the fourth resistor; and the second end of the fourth resistor is connected with a power supply.

The temperature detection circuit adopts the voltage stabilizing circuit to ensure the stability of the external reference voltage provided by the reference voltage circuit and improve the accuracy of the detection result.

In one possible implementation, the reference voltage circuit includes a voltage dividing circuit and a voltage stabilizing circuit; the voltage dividing circuit includes: a second resistor and a third resistor; the voltage stabilizing circuit comprises: a voltage regulator and a fourth resistor;

the first end of the second resistor is connected with the first end of the voltage stabilizing source; the second end of the second resistor is respectively connected with the first end of the third resistor and the reference voltage input port; the second end of the third resistor is grounded;

the first end of the voltage-stabilizing source is connected with the first end of the fourth resistor, the second end of the voltage-stabilizing source is grounded, and the third end of the voltage-stabilizing source is connected with the first end of the fourth resistor; and the second end of the fourth resistor is connected with a power supply.

The temperature detection circuit not only ensures the stability of the external reference voltage provided by the reference voltage circuit and improves the accuracy of the detection result, but also can improve the precision of the detection result by reducing the external reference voltage.

In a second aspect, the present application provides a household appliance comprising: a temperature detection circuit as claimed in any one of the first aspect.

In a third aspect, the present application provides a temperature detection method applied to the temperature detection circuit of any one of the first aspect, the method including:

converting the temperature to be measured into a voltage signal to be measured;

and determining the temperature to be detected according to the external reference voltage of the temperature detection circuit and the voltage signal to be detected.

In a possible implementation manner, the converting the temperature to be measured into the voltage signal to be measured includes:

detecting a connection state between a sampling circuit and a sampling port in the temperature detection circuit, wherein the connection state comprises connection or disconnection;

and converting the temperature to be measured into a voltage signal to be measured when the connection state is determined to be connection.

The application provides a temperature detection circuit, a temperature detection method and a household appliance, wherein a control circuit is used for directly obtaining a voltage signal of a sampling circuit, an external reference voltage is used as a sampling reference voltage, and the external reference voltage is smaller than an internal reference voltage of the control circuit, so that accurate temperature detection can be realized without using an operational amplifier, and the problems of inaccurate result and high cost caused by the operational amplifier are avoided. In addition, by reducing the external reference voltage, the temperature detection precision can be improved, and the accuracy is further improved. The high level is output through the input/output port of the control circuit, the connection state between the sampling circuit and the sampling port is detected, the temperature detection result error under the open circuit condition is avoided, meanwhile, the circuit structure and the control logic are simple, the circuit cost is not increased, and the software compiling difficulty is low.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.

FIG. 1 is a schematic diagram of a temperature detection circuit in the prior art;

fig. 2 is a first schematic structural diagram of a temperature detection circuit provided in the present application;

fig. 3 is a schematic structural diagram of a temperature detection circuit according to the present application;

fig. 4 is a schematic structural diagram of a temperature detection circuit provided in the present application;

fig. 5 is a schematic structural diagram of a temperature detection circuit provided in the present application;

fig. 6 is a schematic structural diagram of a temperature detection circuit provided in the present application;

fig. 7 is a sixth schematic structural diagram of a temperature detection circuit provided in the present application;

fig. 8 is a schematic flow chart of a temperature detection method provided in the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The temperature detection circuit of the household appliance generally adopts an operational amplifier to amplify the signal collected by the sampling circuit and then input the signal to a controller of the household appliance, and the controller determines a temperature value according to the amplified electric signal. For example, fig. 1 is a schematic structural diagram of a temperature detection circuit in the prior art. As shown in fig. 1, the thermocouple is connected to an input terminal of the operational amplifier for converting the detected temperature into a voltage signal to be input to the operational amplifier, and the control chip determines the temperature detected by the thermocouple by sampling an output of the operational amplifier.

The accuracy of the circuit is poor due to the offset voltage of the operational amplifier and the error of the external resistor, and in practical application, if the circuit is used for temperature detection, the operational amplifier needs to be calibrated, so that the complexity of the circuit is increased and the software programming difficulty of a control chip is also improved. And such a temperature detection circuit using an operational amplifier also increases the circuit cost.

In order to avoid the above problems caused by the operational amplifier, it is considered to use the control chip to directly sample and obtain the voltage signal output by the thermocouple, however, since the voltage generated when the thermocouple is heated is very low, the accuracy of the temperature detection result obtained when the control chip directly samples is too low. For example, when the temperature is 4 ℃, the voltage across the thermocouple is 0.158mV, when the temperature is 10 ℃, the voltage across the thermocouple is about 0.4mV, and the reference voltage for the conventional control chip sampling is above 3V, and the resolution is 3V/4096 to 0.73mV calculated according to 12 bits of the sampling bit of the control chip, so it is assumed that the temperature is changed from 4 ℃ to 10 ℃, the control chip cannot distinguish, the sampling precision of the control chip is about 20 ℃, and this precision cannot meet the requirement of practical use.

In addition, when the temperature detection circuit shown in fig. 1 is used, if an open circuit is formed between the sampling circuit and the control chip, the control chip cannot accurately determine the open circuit, and the detection result may be incorrect. If the open circuit between the sampling circuit and the control chip needs to be judged, an additional open circuit detection circuit needs to be added on the basis, the circuit complexity is further increased, and the open circuit detection circuit of the temperature detection circuit based on the operational amplifier is complex in operation and high in software compiling difficulty.

Therefore, the application provides a temperature detection circuit, and the control circuit adopts the external reference voltage as the sampling reference voltage, and the external reference voltage is less than the internal reference voltage of the control circuit, thereby making the control circuit directly obtain the voltage signal output by the sampling circuit, and determining the accurate temperature based on the voltage signal output by the sampling circuit. And because the external reference voltage is lower, the accuracy of the control circuit for determining the temperature based on the voltage signal output by the sampling circuit is higher. In addition, the temperature detection circuit of the application also utilizes the input/output port of the control circuit to judge the connection state between the sampling port and the sampling circuit, and realizes open circuit detection on the basis of not increasing the complexity of the circuit and the difficulty of software compiling. The following examples are given by way of illustration.

Fig. 2 is a first schematic structural diagram of a temperature detection circuit provided in the present application. As shown in fig. 2, the temperature detection circuit includes: a sampling circuit 100, a reference voltage circuit 200, and a control circuit 300.

Wherein, the sampling circuit 100 is connected with the sampling port of the control circuit 300; the reference voltage circuit 200 is connected to a reference voltage input port of the control circuit 300.

The sampling circuit 100 is used for converting the temperature to be measured into a voltage signal to be measured.

The reference voltage circuit 200 is used to provide an external reference voltage to the sampling port of the control circuit 300, where the external reference voltage is less than the internal reference voltage of the control circuit.

The control circuit 300 is used for determining the temperature to be measured according to the external reference voltage and the voltage signal to be measured.

In this embodiment, the temperature to be detected is the temperature of an object to be detected, for example, in a household appliance, the temperature to be detected is the temperature of a pot bottom to be detected, the temperature of a food material to be detected, and the like, which is not limited in this embodiment. The sampling circuit 100 may convert the temperature to be measured into a voltage signal to be measured through an inductive element, for example, the inductive element is a thermosensitive device, such as a thermocouple, a thermal resistor, and the like.

The sampling circuit 100 inputs the voltage signal to be measured into the sampling port of the control circuit 300, and the control circuit 300 determines the temperature to be measured according to the external reference voltage and the voltage signal to be measured. The sampling module of the control circuit 300 equally divides the external reference voltage, so that the smaller the external reference voltage, the higher the sampling accuracy of the control circuit 300.

For example, taking a control chip with 12 bits as an example of the control circuit 300, when the external reference voltage provided by the reference voltage circuit 200 is 0.5V, 500mV/4096 is 0.122mV, that is, the sampling precision of the sampling port is 0.122mV, that is, when the voltage signal to be measured output by the sampling circuit 100 changes by 0.122mV due to a temperature change to be measured, the control circuit 300 can detect the temperature change.

When the external reference voltage provided by the reference voltage circuit 200 is 0.1V, 100mV/4096 is 0.0244mV, i.e., the sampling precision of the sampling port is 0.0244 mV. When the temperature variation to be measured causes the voltage signal to be measured output by the sampling circuit 100 to vary by 0.0244mV, the control circuit 300 can detect the temperature variation. Such sampling accuracy may be desirable for the inductive element in the sampling circuit 100.

The temperature detection circuit provided by the embodiment directly acquires the voltage signal of the sampling circuit by using the control circuit, and simultaneously adopts the external reference voltage as the sampling reference voltage, and the external reference voltage is less than the internal reference voltage of the control circuit, so that the accurate temperature detection can be realized without using an operational amplifier, the problems of inaccurate result, high cost and the like caused by the operational amplifier are avoided, additional calibration is not needed, the circuit complexity is reduced, and the software programming difficulty of the control circuit is also reduced. And the temperature detection circuit can also improve the detection accuracy by reducing the external reference voltage.

In the above embodiment, the sampling circuit 100 may include the thermocouple 101, as shown in fig. 3, the anode of the thermocouple 101 is connected to the sampling port of the control circuit 300, and the cathode of the thermocouple 101 is grounded. The thermocouple 101 converts the temperature to be measured into a voltage signal to be measured, and inputs the voltage signal to the sampling port of the control circuit 300, and the control circuit 300 determines the temperature to be measured according to the external reference voltage and the voltage signal to be measured.

When the sampling circuit 100 includes the thermocouple 101, the external reference voltage provided by the reference voltage circuit 200 cannot be less than the maximum voltage value generated by the thermocouple 101. In an example, taking the thermocouple 101 as a K-type thermocouple as an example, by querying a temperature meter of the K-type thermocouple, the maximum temperature of the K-type thermocouple can reach 1372 ℃, and the corresponding maximum voltage value is 55mV, so that the external reference voltage provided by the reference voltage circuit 200 cannot be smaller than 55mV, and in an example, the external reference voltage range may be 0.06V-0.5V, so that the control circuit 300 can obtain a detection result with higher precision under the condition of a smaller external reference voltage, and also avoid that the external reference voltage is too small to cause abnormal sampling.

In the above embodiments, in order to detect whether the sampling circuit 100 is open or not, the present application further provides a temperature detection circuit, for example, as shown in fig. 4, the sampling port of the control circuit 300 is connected to one input/output port of the control circuit 300 through the first resistor R1.

Optionally, the first resistor R1 may be a resistor external to the input/output port or the sampling port of the control circuit 300, or the first resistor R1 may also be a pull-up resistor internal to the input/output port or the sampling port of the control circuit 300. The adoption of the pull-up resistor in the input/output port or the sampling port can simplify the structure of the temperature detection circuit of the embodiment and further reduce the circuit cost.

The control circuit 300 is configured to control the input/output port to output a high level, and determine a connection state between the sampling circuit 100 and the sampling port according to a sampling value of the sampling port, where the connection state includes connection or disconnection; and when the connection state between the sampling circuit 100 and the sampling port is determined to be connected, the input/output port is controlled to be in an input state, and the temperature to be measured is determined according to the external reference voltage and the voltage signal to be measured.

In this embodiment, the control circuit 300 may control the input/output port to output a high level when the power is turned on, and the high level output by the input/output port is an internal reference voltage of the control circuit. At this time, if the connection between the sampling circuit 100 and the sampling port is disconnected, the control circuit samples the high level of the input/output port through the first resistor R1, that is, the sampling value is the maximum value; if the sampling circuit 100 is connected to the sampling port, the voltage sampled by the control circuit 300 is the voltage value of the first resistor R1 connected in parallel to the sampling circuit 100, which is inevitably smaller than the high level of the input/output port. Therefore, when the input/output port outputs a high level, the control circuit 300 may determine the connection state between the sampling circuit 100 and the sampling port according to the sampling value of the sampling port.

When the input/output port outputs a high level, the control circuit 300 determines that the connection state between the sampling circuit 100 and the sampling port is disconnected when a difference between a sampling value of the sampling port and an internal reference voltage of the control circuit 300 is less than or equal to a preset value, or the control circuit 300 determines that the connection state between the sampling circuit 100 and the sampling port is connected when a difference between a sampling value of the sampling port and an internal reference voltage of the control circuit 300 is greater than a preset value. The size of the preset value can be set according to actual conditions.

For example, the internal reference voltage of the control circuit 300 is 5V, the preset value is 0.02V, when the input/output port outputs a high level, if the sampling value of the control circuit 300 at the sampling port is 4.99V, it is obvious that the difference between the internal reference voltage and the internal reference voltage is smaller than the preset value, so as to determine that the connection state between the sampling circuit 100 and the sampling port is disconnected; if the sampling value of the control circuit 300 at the sampling port is 4.8V, it is obvious that the difference value between the sampling value and the internal reference voltage is greater than the preset value, and thus the connection state between the sampling circuit 100 and the sampling port is determined to be connection.

For example, the internal reference voltage of the control circuit 300 is 5V, the preset value is 0V, and when the input/output port outputs a high level, if the sampling value of the control circuit 300 at the sampling port is 5V, it is obvious that the difference between the internal reference voltage and the internal reference voltage is equal to the preset value, so as to determine that the connection state between the sampling circuit 100 and the sampling port is disconnected; if the sampling value of the control circuit 300 at the sampling port is 4.99V, it is obvious that the difference value from the internal reference voltage is greater than the preset value, and thus the connection state between the sampling circuit 100 and the sampling port is determined to be connection.

After determining that the connection state between the sampling circuit 100 and the sampling port is connection, the control circuit 300 controls the input/output port to be in an input state, so that the first resistor R1 is suspended, and temperature detection of the sampling port through the sampling circuit 100 is not affected.

The temperature detection circuit of the embodiment utilizes the input/output port of the control circuit to output high level, detects the connection state between the sampling circuit and the sampling port, avoids temperature detection result errors under the condition of open circuit, has a simple circuit structure, does not increase circuit cost, and has simple control method and judgment method and lower software compiling difficulty.

In the above embodiments, the reference voltage circuit 200 may adopt different implementations to provide the external reference voltage for the control circuit 300. The reference voltage circuit 200 may include a voltage divider circuit 201 and/or a voltage regulator circuit 202.

As shown in fig. 5, the reference voltage circuit 200 includes a voltage dividing circuit 201; the voltage dividing circuit 201 includes: a second resistor R2 and a third resistor R3.

The first end of the second resistor R2 is connected with a power supply; a second end of the second resistor R2 is respectively connected with a first end of the third resistor R3 and the reference voltage input port; the second terminal of the third resistor R3 is connected to ground.

The voltage divider 201 divides the power voltage and inputs the divided power voltage to the control circuit 300, the magnitude of the external reference voltage is determined by the power voltage, the second resistor R2 and the third resistor R3, and in practical applications, the magnitudes of the second resistor R2 and the third resistor R3 can be set according to the magnitude of the required external reference voltage. The voltage divider circuit 201 can provide the control circuit 300 with the required lower external reference voltage by the reference voltage circuit 200.

As shown in FIG. 6, the reference voltage circuit 200 includes a regulation circuit 202; the stabilizing circuit 202 includes: a voltage regulator 203 and a fourth resistor R4.

A first end of the fourth resistor R4 and the reference voltage input port are respectively connected with a first end of the voltage regulator 203, a second end of the voltage regulator 203 is grounded, and a third end of the voltage regulator 203 is connected with a first end of the fourth resistor R4; a second terminal of the fourth resistor R4 is connected to a power supply.

For example, voltage regulator 203 may be a TL431 controllable precision voltage regulator. Illustratively, the first terminal of TL431 outputs a voltage of 2.5V to control circuit 300. The adoption of the voltage stabilizing circuit 202 ensures the stability of the external reference voltage provided by the reference voltage circuit 200 and improves the accuracy of the detection result.

As shown in FIG. 7, the reference voltage circuit 200 includes a voltage divider circuit 201 and a voltage regulator circuit 202; the voltage dividing circuit 201 includes: a second resistor R2 and a third resistor R3; the stabilizing circuit 202 includes: a voltage regulator 203 and a fourth resistor R4.

Wherein, the first end of the second resistor R2 is connected with the first end of the voltage regulator 203; a second end of the second resistor R2 is respectively connected with a first end of the third resistor R3 and the reference voltage input port; the second end of the third resistor R3 is grounded;

the first end of the voltage regulator 203 is connected with the first end of a fourth resistor R4, the second end of the voltage regulator 203 is grounded, and the third end of the voltage regulator 203 is connected with the first end of a fourth resistor R4; a second terminal of the fourth resistor R4 is connected to a power supply.

For example, voltage regulator 203 may be a TL431 controllable precision voltage regulator. Illustratively, the first terminal of TL431 outputs a voltage of 2.5V to control circuit 300. Compared with fig. 6, in the circuit of fig. 7, the voltage output from the first terminal of the TL431 is divided again by the voltage dividing circuit 201 and then input to the control circuit 300, so that the external reference voltage reaches a lower voltage value. Therefore, the stability of the external reference voltage provided by the reference voltage circuit 200 is ensured, the accuracy of the detection result is improved, and the accuracy of the detection result can be improved by reducing the external reference voltage.

The application also relates to a household appliance, which comprises the temperature detection circuit in any one of the embodiments.

In addition, the present application further provides a temperature detection method, which is applied to the temperature detection circuit in any of the above embodiments, as shown in fig. 8, the method includes:

s801, converting the temperature to be measured into a voltage signal to be measured;

s802, determining the temperature to be measured according to the external reference voltage and the voltage signal to be measured of the temperature detection circuit.

Optionally, converting the temperature to be measured into a voltage signal to be measured includes:

detecting the connection state between a sampling circuit and a sampling port in a temperature detection circuit, wherein the connection state comprises connection or disconnection;

and converting the temperature to be measured into a voltage signal to be measured when the connection state is determined to be connection.

The temperature detection method of the embodiment of the application is applied to the temperature detection circuit in any one of the embodiments, and the implementation principle and the technical effect are similar, and are not repeated here.

In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described embodiments of the apparatus are merely illustrative, and for example, the division of modules is only one logical division, and other divisions may be realized in practice, for example, a plurality of modules may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or modules, and may be in an electrical, mechanical or other form.

Those of ordinary skill in the art will understand that: all or a portion of the steps of implementing the above-described method embodiments may be performed by hardware associated with program instructions. The program may be stored in a computer-readable storage medium. When executed, the program performs steps comprising the method embodiments described above; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the embodiments of the present application, and are not limited thereto; although the embodiments of the present application have been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the embodiments of the present application.

Claims (12)

1. A temperature sensing circuit, comprising: a sampling circuit (100), a reference voltage circuit (200), and a control circuit (300);

wherein the sampling circuit (100) is connected with a sampling port of the control circuit (300); the reference voltage circuit (200) is connected with a reference voltage input port of the control circuit (300);

the sampling circuit (100) is used for converting the temperature to be measured into a voltage signal to be measured;

the reference voltage circuit (200) is used for providing an external reference voltage for a sampling port of the control circuit (300), and the external reference voltage is smaller than an internal reference voltage of the control circuit (300);

the control circuit (300) is used for determining the temperature to be measured according to the external reference voltage and the voltage signal to be measured.

2. The circuit of claim 1, wherein the sampling circuit (100) comprises a thermocouple (101);

the positive electrode of the thermocouple (101) is connected with the sampling port of the control circuit (300), and the negative electrode of the thermocouple (101) is grounded.

3. The circuit of claim 1, wherein the sampling port of the control circuit (300) is connected to an input/output port of the control circuit (300) via a first resistor R1;

the control circuit (300) is used for controlling the input/output port to output a high level and determining the connection state between the sampling circuit (100) and the sampling port according to the sampling value of the sampling port, wherein the connection state comprises connection or disconnection;

the control circuit (300) is used for controlling the input/output port to be in an input state when the connection state between the sampling circuit (100) and the sampling port is determined to be connected, and determining the temperature to be measured according to the external reference voltage and the voltage signal to be measured.

4. The circuit of claim 3, wherein the first resistor R1 is a pull-up resistor in the sampling port or a pull-up resistor in the input-output port.

5. The circuit according to claim 3, wherein when the input/output port outputs a high level, the control circuit (300) is configured to determine that the connection state between the sampling circuit (100) and the sampling port is disconnected when a difference between a sampled value of the sampling port and an internal reference voltage of the control circuit (300) is smaller than or equal to a preset value, or the control circuit (300) is configured to determine that the connection state between the sampling circuit (100) and the sampling port is connected when a difference between a sampled value of the sampling port and an internal reference voltage of the control circuit (300) is greater than a preset value.

6. The circuit according to any of claims 1-5, wherein the reference voltage circuit (200) comprises a voltage divider circuit (201) and/or a voltage regulator circuit (202).

7. The circuit according to claim 6, wherein the reference voltage circuit (200) comprises a voltage divider circuit (201); the voltage dividing circuit (201) includes: a second resistor R2 and a third resistor R3;

a first end of the second resistor R2 is connected with a power supply; a second end of the second resistor R2 is connected to the first end of the third resistor R3 and the reference voltage input port, respectively; the second end of the third resistor R3 is grounded.

8. The circuit of claim 6, wherein the reference voltage circuit (200) comprises a regulation circuit (202); the voltage regulator circuit (202) includes: a regulator (203) and a fourth resistor R4;

the first end of the fourth resistor R4 and the reference voltage input port are respectively connected with the first end of the voltage regulator (203), the second end of the voltage regulator (203) is grounded, and the third end of the voltage regulator (203) is connected with the first end of the fourth resistor R4; a second terminal of the fourth resistor R4 is connected to a power supply.

9. The circuit of claim 6, wherein the reference voltage circuit (200) comprises a voltage divider circuit (201) and a voltage regulator circuit (202); the voltage dividing circuit (201) includes: a second resistor R2 and a third resistor R3; the voltage regulator circuit (202) includes: a regulator (203) and a fourth resistor R4;

a first end of the second resistor R2 is connected with a first end of the voltage stabilizing source (203); a second end of the second resistor R2 is connected to the first end of the third resistor R3 and the reference voltage input port, respectively; a second end of the third resistor R3 is grounded;

a first end of the voltage regulator (203) is connected with a first end of the fourth resistor R4, a second end of the voltage regulator (203) is grounded, and a third end of the voltage regulator (203) is connected with a first end of the fourth resistor R4; a second terminal of the fourth resistor R4 is connected to a power supply.

10. A household appliance, characterized in that it comprises: a temperature sensing circuit according to any of claims 1 to 9.

11. A temperature detection method applied to the temperature detection circuit according to any one of claims 1 to 9, the method comprising:

converting the temperature to be measured into a voltage signal to be measured;

and determining the temperature to be detected according to the external reference voltage of the temperature detection circuit and the voltage signal to be detected.

12. The method of claim 11, wherein converting the temperature to be measured into a voltage signal to be measured comprises:

detecting a connection state between a sampling circuit and a sampling port in the temperature detection circuit, wherein the connection state comprises connection or disconnection;

and converting the temperature to be measured into a voltage signal to be measured when the connection state is determined to be connection.

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