Thermistor resistance measurement circuit and method, storage medium

Abstract

The present application relates to the field of electrical data measurement technology, and in particular to a thermistor resistance measurement circuit and method, and storage medium. In the thermistor resistance measurement circuit and method provided in the present application, even if the power supply voltage changes, the amount of current flowing through the thermistor will not change. Through such a design, the error or change of the power supply voltage will not affect the error of the thermistor resistance measurement, so the correction of the power supply voltage can be omitted or reduced, and only the range of the power supply voltage needs to be known without determining the specific value of the power supply voltage, and the switch state of the first switch and the second switch can be adjusted accordingly, so that the circuit works in a suitable measurement gear.

Description

Technical Field

[0001] The present application relates to the technical field of electrical data measurement, and in particular to a resistance measurement circuit and method for a thermistor, and a storage medium. Background Art

[0002] The resistance of a thermistor changes with temperature. Therefore, the temperature information of the environment in which the thermistor is located can be determined by detecting the resistance of the thermistor.

[0003] In the thermistor resistance measurement circuit proposed in the related art, in order to ensure the measurement accuracy, the power supply voltage that provides the circuit with working power needs to be calibrated frequently, because a slight deviation in the power supply voltage will lead to a significant decrease in the resistance measurement accuracy. Summary of the invention

[0004] In view of this, the present application proposes a thermistor resistance measurement circuit and method, and a storage medium.

[0005] In a first aspect, a thermistor resistance measurement circuit is proposed, comprising:

[0006] A first resistor and a first switch are connected in series between a first node and a second node, wherein the first node is used to connect to a supply voltage;

[0007] A second resistor and a second switch are connected in series between the first node and the second node in a manner of being connected in parallel with the first resistor and the first switch, wherein the resistance of the second resistor is smaller than that of the first resistor;

[0008] a first switch transistor connected between the second node and a third node, wherein the third node is connected to a ground voltage via the thermistor;

[0009] A fifth resistor, a second switch transistor and a sixth resistor are sequentially connected in series between the first node and the ground voltage;

[0010] A first operational amplifier having a first non-inverting input terminal connected to a reference voltage, a first inverting input terminal connected between the second switch transistor and the sixth resistor, and a first output terminal connected to a gate of the second switch transistor;

[0011] a second operational amplifier having a second non-inverting input terminal connected between the fifth resistor and the second switch transistor, a second inverting input terminal connected between the first resistor and the first switch and between the second resistor and the second switch, and a second output terminal connected to the gate of the first switch transistor;

[0012] The detection unit has a detection terminal connected to the third node, and is used to detect the voltage across the thermistor and determine the resistance of the thermistor according to the voltage across the thermistor.

[0013] In some possible implementations, determining the resistance of the thermistor according to the voltage across the thermistor includes:

[0014] When the first switch is turned on and the second switch is turned off, determining the resistance value of the thermistor based on formula (1);

[0015] When the second switch is turned on and the first switch is turned off, determining the resistance value of the thermistor based on formula (2);

[0016]

[0017]

[0018] Among them, R c is the resistance of the thermistor, Vc is the voltage across the thermistor, Vref is the reference voltage, R1 is the resistance of the first resistor, R2 is the resistance of the second resistor, R5 is the resistance of the fifth resistor, and R6 is the resistance of the sixth resistor.

[0019] In some possible implementations, the following further includes:

[0020] A third resistor and a third switch are connected in series between the first node and the second node in a manner of being connected in parallel with the first resistor and the first switch, wherein a resistance value of the third resistor is smaller than that of the second resistor;

[0021] A fourth resistor and a fourth switch are connected in series between the first node and the second node in parallel with the first resistor and the first switch, wherein a resistance value of the fourth resistor is smaller than that of the third resistor.

[0022] In some possible implementations, the detection unit is further used for:

[0023] When the third switch is turned on and the first switch, the second switch and the fourth switch are all turned off, the resistance value of the thermistor is determined based on formula (3);

[0024] When the fourth switch is turned on and the first switch, the second switch and the third switch are all turned off, the resistance value of the thermistor is determined based on formula (4);

[0025]

[0026]

[0027] Among them, R c is the resistance of the thermistor, Vc is the voltage across the thermistor, Vref is the reference voltage, R3 is the resistance of the second resistor, R4 is the resistance of the fourth resistor, R5 is the resistance of the fifth resistor, and R6 is the resistance of the sixth resistor.

[0028] In some possible implementations, the first resistor and the first switch are sequentially connected in series between the first node and the second node, and the second resistor and the second switch are sequentially connected in series between the first node and the second node.

[0029] In some possible implementations, the detection unit is further configured to determine the temperature of the thermistor according to the resistance value of the thermistor.

[0030] In some possible implementations, the detection unit includes:

[0031] A third operational amplifier having a third non-inverting input terminal, a third inverting input terminal and a third output terminal, wherein the third non-inverting input terminal constitutes the detection terminal, and the third inverting input terminal is connected to the third output terminal;

[0032] The analog-to-digital converter is connected to the third output terminal and is used to convert the analog voltage signal provided by the third output terminal into a digital voltage signal.

[0033] In a second aspect, a method for measuring the resistance of a thermistor is provided, which is applied to the circuit as described in the first aspect, and the method comprises:

[0034] In response to the supply voltage being greater than a threshold voltage, the first switch is controlled to be turned on and the second switch is turned off, and the resistance value of the thermistor is determined based on formula (1);

[0035] In response to the supply voltage being less than the threshold voltage, controlling the second switch to be turned on and the first switch to be turned off, and determining the resistance value of the thermistor based on formula (2);

[0036]

[0037]

[0038] Among them, R c is the resistance of the thermistor, Vc is the voltage across the thermistor, Vref is the reference voltage, R1 is the resistance of the first resistor, R2 is the resistance of the second resistor, R5 is the resistance of the fifth resistor, and R6 is the resistance of the sixth resistor.

[0039] In a third aspect, a method for measuring the resistance of a thermistor is provided, which is applied to the circuit as described in the first aspect, and the method comprises:

[0040] In response to the supply voltage being greater than a first threshold voltage, the first switch is controlled to be turned on, the second switch, the third switch and the fourth switch are all turned off, and the resistance value of the thermistor is determined based on formula (1);

[0041] In response to the supply voltage being less than the first threshold voltage and greater than the second threshold voltage, the second switch is controlled to be turned on, the first switch, the third switch and the fourth switch are all turned off, and the resistance value of the thermistor is determined based on formula (2);

[0042] In response to the supply voltage being less than the second threshold voltage and greater than a third threshold voltage, the third switch is controlled to be turned on, the first switch, the second switch and the third switch are all turned off, and the resistance value of the thermistor is determined based on formula (3);

[0043] In response to the supply voltage being less than the third threshold voltage, the fourth switch is controlled to be turned on, the first switch, the second switch and the third switch are all turned off, and the resistance value of the thermistor is determined based on formula (4);

[0044]

[0045]

[0046]

[0047]

[0048] Among them, R c is the resistance of the thermistor, Vc is the voltage across the thermistor, Vref is the reference voltage, R1 is the resistance of the first resistor, R2 is the resistance of the second resistor, R3 is the resistance of the third resistor, R4 is the resistance of the fourth resistor, R5 is the resistance of the fifth resistor, and R6 is the resistance of the sixth resistor.

[0049] In a fourth aspect, a computer-readable storage medium is proposed, which stores a computer program. When the computer program is executed by a computer, the method described in the second aspect or the third aspect is implemented.

[0050] According to the thermistor resistance measurement circuit and method proposed in the present application, even when the power supply voltage changes, the amount of current flowing through the thermistor will not change. Through such a design, the error or change of the power supply voltage will not affect the error of the thermistor resistance measurement, so the correction of the power supply voltage can be omitted or reduced, and only the range of the power supply voltage needs to be known (no need to determine the specific value of the power supply voltage), and the switch states of the first switch and the second switch can be adjusted accordingly, so that the circuit works in a suitable measurement gear. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present application, rather than limiting the present application.

[0052] Figure 1 is a schematic diagram of the structure of a resistance measurement circuit provided in an embodiment of the present application;

[0053] Figure 2 is a schematic diagram of the structure of a resistance measurement circuit provided in an embodiment of the present application;

[0054] Figure 3 is a schematic diagram of the structure of a resistance measurement circuit provided in an embodiment of the present application;

[0055] Figure 4 is a schematic flow chart of a resistance measurement method provided in an embodiment of the present application;

[0056] Figure 5 It is a schematic flow chart of the resistance measurement method provided in the embodiment of the present application.

[0057] Description of reference numerals:

[0058] V1-supply voltage, Vref-reference voltage;

[0059] 11-first node, 12-second node, 13-third node;

[0060] Rc-thermistor;

[0061] R1-first resistor, R2-second resistor, R3-third resistor, R4-fourth resistor, R5-fifth resistor, R6-sixth resistor;

[0062] SW1-first switch, SW2-second switch, SW3-third switch, SW4-fourth switch;

[0063] Q1-first switching transistor, Q2-second switching transistor;

[0064] OP1-first operational amplifier, P11-first non-inverting input terminal, P12-first inverting input terminal, P13-first output terminal;

[0065] OP2-second operational amplifier, P21-second non-inverting input terminal, P22-second inverting input terminal, P23-second output terminal;

[0066] OP3-third operational amplifier, P31-third non-inverting input terminal, P32-third inverting input terminal, P33-third output terminal. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the embodiment of the present application will be clearly and completely described below in conjunction with the drawings of the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, rather than all the embodiments. Based on the described embodiment of the present application, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of this application. It can be understood that, in the absence of conflict, some technical means of the various embodiments described herein can be replaced or combined with each other.

[0068] In the description of this application, if there are terms such as "first", "second", etc., they are only used to distinguish the objects described and do not have any order or technical meaning. Therefore, an object defined as "first", "second", etc. may explicitly or implicitly include one or more of the objects, and, for example, the term "first element" itself does not mean the existence of the "second element", and the term "second element" itself does not mean the existence of the "first element". In addition, "one" or "a" and similar words do not indicate a quantity limitation, but rather indicate the existence of at least one, and "multiple" means not less than two.

[0069] In the description of this application, if there is a term "based on" or "according to", it is used to describe one or more factors that affect the determination. The term does not exclude additional factors that affect the determination. That is, the determination may be based only on these factors or at least partially on these factors. For example, the phrase "based on A, B is determined". In this case, A is a factor that affects the determination of B. This phrase does not exclude that the determination of B may also be based on C.

[0070] In the description of the present application, if the term “configured to” is present, it can generally be interchanged with “having the ability to…”, “designed to”, “for” or “able to” depending on the context.

[0071] Figure 1 A resistance measurement circuit (hereinafter, sometimes referred to as the circuit) provided in an embodiment of the present application is shown, which can measure the resistance of a thermistor Rc included in the circuit.

[0072] like Figure 1 As shown, the circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a first switch SW1, a second switch SW2, a third switch SW3, a fourth switch SW4, a fifth switch, a first switch transistor Q1, a second switch transistor Q2, a first operational amplifier OP1, a second operational amplifier OP2 and a detection unit.

[0073] The first resistor R1 and the first switch SW1 are sequentially connected in series between the first node 11 and the second node 12, so the first resistor R1 is closer to the first node 11, and the first switch SW1 is closer to the second node 12. The first node 11 is used to connect to the power supply voltage V1, and the power supply voltage V1 can be provided by an external power supply circuit that is not included in the circuit (not a part of the circuit).

[0074] The second resistor R2 and the second switch SW2 are connected in series between the first node 11 and the second node 12 in parallel with the first resistor R1 and the first switch SW1 . Therefore, the second resistor R2 is closer to the first node 11 and the second switch SW2 is closer to the second node 12 .

[0075] The third resistor R3 and the third switch SW3 are also connected in series between the first node 11 and the second node 12 in parallel with the first resistor R1 and the first switch SW1 . Therefore, the third resistor R3 is closer to the first node 11 , and the third switch SW3 is closer to the second node 12 .

[0076] The fourth resistor R4 and the fourth switch SW4 are also connected in series between the first node 11 and the second node 12 in parallel with the first resistor R1 and the first switch SW1 . Therefore, the fourth resistor R4 is closer to the first node 11 , and the fourth switch SW4 is closer to the second node 12 .

[0077] Furthermore, the resistance of the first resistor R1, the resistance of the second resistor R2, the resistance of the third resistor R3 and the resistance of the fourth resistor R4 decrease in sequence. Exemplarily, the resistance of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are 1M ohm, 100K ohm, 10K ohm and 1K ohm respectively. The first switch SW1, the second switch SW2, the third switch SW3 and the fourth switch SW4 can be transistor switches.

[0078] In this embodiment, the first series branch formed by the first resistor R1 and the first switch SW1, the second series branch formed by the second resistor R2 and the second switch SW2, the third series branch formed by the third resistor R3 and the third switch SW3, and the fourth series branch formed by the fourth resistor R4 and the fourth switch SW4 are connected in parallel. Based on this, in practical applications, only one of the four series branches can be coupled to the thermistor Rc under test by controlling the switch states of the first to fourth switches according to the size of the power supply voltage V1, so that the current Ic flowing through the thermistor Rc is always kept within a suitable range, and then the voltage Vc across the thermistor Rc is kept within a suitable range, so as to facilitate the detection of the detection unit. For example, when the power supply voltage V1 is very high, the first series branch with a relatively large resistance is coupled to the thermistor Rc, and the other three series branches are decoupled from the thermistor Rc, and when the power supply voltage V1 is very small, the fourth series branch with a relatively small resistance is coupled to the thermistor Rc, and the other three series branches are decoupled from the thermistor Rc. It can be seen that, through the aforementioned four series branches, the circuit has multiple measurement gears and can adapt to power supply voltages V1 of different sizes, which helps to expand the application scenarios of the circuit.

[0079] The first switch transistor Q1 is connected between the second node 12 and the third node 13, wherein the third node 13 is connected to the ground voltage GND via the thermistor Rc. In addition, the first switch transistor Q1 may be a P-channel transistor.

[0080] The fifth resistor R5, the second switch transistor Q2 and the sixth resistor R6 are sequentially connected in series between the first node 11 and the ground voltage GND. The second switch transistor Q2 may be an N-channel transistor.

[0081] The first operational amplifier OP1 has a first positive input terminal P11, a first negative input terminal P12 and a first output terminal P13, wherein the first positive input terminal P11 is connected to a reference voltage Vref, the first negative input terminal P12 is connected between the second switching transistor Q2 and the sixth resistor R6, and the first output terminal P13 is connected to the gate of the second switching transistor Q2.

[0082] The second operational amplifier OP2 has a second positive input terminal P21, a second negative input terminal P22 and a second output terminal P23, wherein the second positive input terminal P21 is connected between the fifth resistor R5 and the second switching transistor Q2, the second negative input terminal P22 is connected between the first resistor R1 and the first switch SW1, between the second resistor R2 and the second switch SW2, between the third resistor R3 and the third switch SW3, and between the fourth resistor R4 and the fourth switch SW4, and the second output terminal P23 is connected to the gate of the first switching transistor Q1.

[0083] The detection unit has a detection end connected to the third node 13 , and is used to detect the voltage of the third node 13 , ie, the voltage across the thermistor Rc, through the detection end, and determine the resistance of the thermistor Rc according to the voltage across the thermistor Rc.

[0084] The above-mentioned determination of the resistance value of the thermistor Rc according to the voltage across the thermistor Rc may specifically include:

[0085] When the first switch SW1 is turned on and the second switch SW2, the third switch SW3 and the fourth switch SW4 are all turned off, the resistance value of the thermistor Rc is determined based on the following formula (1);

[0086] When the second switch SW2 is turned on and the first switch SW1, the third switch SW3 and the fourth switch SW4 are all turned off, the resistance value of the thermistor Rc is determined based on the following formula (2);

[0087] When the third switch SW3 is turned on and the first switch SW1, the second switch SW2 and the fourth switch SW4 are all turned off, the resistance value of the thermistor Rc is determined based on the following formula (3);

[0088] When the fourth switch SW4 is turned on and the first switch SW1 , the second switch SW2 and the third switch SW3 are all turned off, the resistance value of the thermistor Rc is determined based on the following formula (4);

[0089]

[0090]

[0091]

[0092]

[0093] Among them, R c is the resistance of the thermistor Rc, Vc is the voltage across the thermistor Rc, Vref is the reference voltage Vref, R1 is the resistance of the first resistor R1, R2 is the resistance of the second resistor R2, R3 is the resistance of the third resistor R3, R4 is the resistance of the fourth resistor R4, R5 is the resistance of the fifth resistor R5, and R6 is the resistance of the sixth resistor R6.

[0094] It should be understood that Vref, R1, R2, R3, R4, R5 and R6 are all known quantities, and these seven known quantities can be pre-stored in a memory coupled to the circuit and can be called by a processor coupled to the memory. Vc can be detected by the detection unit through the detection terminal connected to the third node 13.

[0095] Here, in order to facilitate readers to distinguish the reference numerals of resistors and the resistance algebra of resistors, the two are intentionally distinguished: the resistance algebra of resistors uses subscripts, while the reference numerals of resistors do not use subscripts.

[0096] In the embodiment of the present application, Figure 1 The first switch transistor Q1, the first operational amplifier OP1 and the sixth resistor R6 combined in this way constitute a constant current source circuit, and the current of the constant current source circuit is Vref / R6. Figure 1 The first resistor R1 and the first switch SW1, the second resistor R2 and the second switch SW2, the third resistor R3 and the third switch SW3, the fourth resistor R4 and the fourth switch SW4, which are combined in a certain manner, respectively form another constant current source circuit with different gears with the second operational amplifier OP2 and the first switch transistor Q1.

[0097] Specifically, when the current flowing through the fifth resistor R5 increases, the voltage on the sixth resistor R6 increases, resulting in an increase in the voltage of the first inverting input terminal P12 of the first operational amplifier OP1, which causes the difference between the first non-inverting input terminal and the first inverting input terminal P12 to decrease. Therefore, the voltage of the first output terminal P13 of the first operational amplifier OP1 decreases, the driving voltage of the first switch transistor Q1 decreases, and the equivalent resistance of the first switch transistor Q1 increases (the first switch transistor Q1 in the circuit is equivalent to a variable resistor), resulting in a decrease in the current flowing through the fifth resistor R5. It can be seen that when the current flowing through the fifth resistor R5 increases, it will reversely cause it to decrease, thereby forming a negative feedback, so virtual short (Virtual Short) and virtual open (Virtual Open) are established, so that the voltage of the first inverting input terminal P12 is equal to the voltage of the first non-inverting input terminal P11, and equal to the voltage across the sixth resistor R6, both of which are the reference voltage Vref. Therefore, the current Ic flowing through the fifth resistor R5, the first switch transistor Q1 and the sixth resistor R6 is constant at Vref / R6.

[0098] Therefore, the voltage drop across the fifth resistor R5 is (Vref / R6)*R5, and the voltage V op2+ V op2+ =V1-(Vref / R6)*R5. And during the operation, the voltage V op2- is equal to the voltage of the second positive phase input terminal P21, so V op2- =V1-(Vref / R6)*R5.

[0099] Based on this, when the first switch SW1 is turned on and the second switch SW2, the third switch SW3 and the fourth switch SW4 are all turned off, the current I flowing through the thermistor Rc is c = (V1- V op2- ) / R1=(Vref / R6)*R5 / R1, which has nothing to do with the size of V1. And, the voltage Vc across the thermistor Rc=Ic* R c = (Vref / R6) * R5 * Rc / R1, based on this, the above formula (1) can be obtained.

[0100] When the second switch SW2 is turned on and the first switch SW1, the third switch SW3 and the fourth switch SW4 are all turned off, the current Ic flowing through the thermistor Rc = (V1-V op2- ) / R2=(Vref / R6)*R5 / R2, which has nothing to do with the size of V1. And, the voltage Vc across the thermistor Rc=Ic* R c = (Vref / R6) * R5 * Rc / R1, based on this, the above formula (2) can be obtained.

[0101] When the third switch SW3 is turned on and the first switch SW1, the second switch SW2 and the fourth switch SW4 are all turned off, the current Ic flowing through the thermistor Rc = (V1-V op2- ) / R2=(Vref / R6)*R5 / R2, which has nothing to do with the size of V1. And, the voltage Vc across the thermistor Rc=Ic* R c = (Vref / R6) * R5 * Rc / R3, based on this, the above formula (3) can be obtained.

[0102] When the fourth switch SW4 is turned on and the first switch SW1, the second switch SW2 and the third switch SW3 are all turned off, the current Ic flowing through the thermistor Rc = (V1-V op2- ) / R2=(Vref / R6)*R5 / R4, which has nothing to do with the size of V1. And, the voltage Vc across the thermistor Rc=Ic* R c = (Vref / R6) * R5 * Rc / R4, based on this, the above formula (4) can be obtained.

[0103] According to the above discussion, when the power supply voltage V1 changes, for example, the power supply voltage V1 decreases due to aging of the power supply circuit providing the power supply voltage V1, or the power supply voltage V1 increases or decreases due to replacement of the power supply circuit providing the power supply voltage V1, no matter which of the four series branches is coupled to the thermistor Rc under test at this time, the current Ic flowing through the thermistor Rc will not change. Through such a design, the error of the power supply voltage V1 will not affect the error of the resistance measurement of the thermistor Rc, so the correction of the power supply voltage V1 can be omitted or reduced, and only the range of the power supply voltage V1 needs to be known (no need to determine the specific value of the power supply voltage V1), and the switch states of the first switch SW1, the second switch SW2, the third switch SW3 and the fourth switch SW4 can be adjusted accordingly, so that the circuit works in a suitable measurement gear.

[0104] In addition, since the first switch SW1, the second switch SW2, the third switch SW3 and the fourth switch SW4 are all in the negative feedback loop of the second operational amplifier OP2, the difference in the on-resistance of the four switches will not affect the measurement accuracy of the circuit. Therefore, the measurement accuracy of the entire circuit is only affected by the reference voltage Vref and the resistance value of the resistor. Therefore, even if a low-priced 1% or 0.1% precision resistor is used, the resistance measurement accuracy of the thermistor Rc of the circuit can be easily guaranteed.

[0105] In this embodiment, the detection unit includes a third operational amplifier OP3 and an analog to digital converter (ADC). The third operational amplifier OP3 has a third positive phase input terminal P31, a third negative phase input terminal P32 and a third output terminal P33, and the third positive phase input terminal P31 serves as the aforementioned detection terminal of the detection unit, that is, the third positive phase input terminal P31 is connected to the aforementioned third node 13, so that the voltage of the third node 13 can be detected via the third positive phase input terminal P31, which is also the voltage Vc across the thermistor Rc. The third negative phase input terminal P32 is connected to the third output terminal P33, thereby using the third operational amplifier OP3 to construct a voltage follower circuit, so that the voltage of the third output terminal P33 is always equal to the voltage of the third positive phase input terminal P31, that is, the voltage Vc across the thermistor Rc. The analog to digital converter is connected to the third output terminal P33 of the third operational amplifier OP3, and is used to convert the analog voltage signal (Vc) provided by the third output terminal P33 into a digital voltage signal that is easier to process.

[0106] In this embodiment, the detection unit is further used to determine the temperature of the thermistor Rc according to the resistance value of the thermistor Rc, so that the circuit has a temperature measurement function.

[0107] although Figure 1 Only the circuit with four measuring gears is shown, but it should be understood that the measuring gears of the circuit can also be designed to be less than four or more than four. For example, Figure 2 As shown, a resistance measurement circuit having only two measurement gears is shown.

[0108] In addition, Figure 3 In another embodiment shown, the resistance measurement circuit has only one measurement position. Figure 3 In the illustrated embodiment, the resistance value of the thermistor Rc can be determined based on equation (1).

[0109] The present application also provides a method for measuring the resistance of a thermistor Rc. The method can be applied to the aforementioned resistance measurement circuit, especially Figure 2 The resistance measurement circuit shown includes:

[0110] S401 , in response to the supply voltage V1 being greater than the threshold voltage, controlling the first switch SW1 to be turned on and the second switch SW2 to be turned off, and determining the resistance value of the thermistor Rc based on equation (1).

[0111] S402 , in response to the supply voltage V1 being less than the aforementioned threshold voltage, the second switch SW2 is controlled to be turned on, the first switch SW1 is turned off, and the resistance value of the thermistor Rc is determined based on equation (2).

[0112] The present application also provides a method for measuring the resistance of a thermistor Rc. The method can be applied to the aforementioned resistance measurement circuit, especially Figure 1 The resistance measurement circuit shown includes:

[0113] S501 , in response to the supply voltage V1 being greater than the first threshold voltage, the first switch SW1 is controlled to be turned on, the second switch SW2 , the third switch SW3 and the fourth switch SW4 are all turned off, and the resistance value of the thermistor Rc is determined based on the above formula (1).

[0114] S502, in response to the supply voltage V1 being less than the aforementioned first threshold voltage and greater than the second threshold voltage, the second switch SW2 is controlled to be turned on, and the first switch SW1, the third switch SW3 and the fourth switch SW4 are all turned off, and the resistance value of the thermistor Rc is determined based on the aforementioned formula (2).

[0115] S503, in response to the supply voltage V1 being less than the second threshold voltage and greater than the third threshold voltage, the third switch SW3 is controlled to be turned on, the first switch SW1, the second switch SW2 and the third switch SW3 are all turned off, and the resistance value of the thermistor Rc is determined based on the above formula (3).

[0116] S504 , in response to the supply voltage V1 being less than the aforementioned third threshold voltage, the fourth switch SW4 is controlled to be turned on, the first switch SW1 , the second switch SW2 and the third switch SW3 are all turned off, and the resistance value of the thermistor Rc is determined based on the aforementioned formula (4).

[0117] The embodiment of the present application further provides a computer-readable storage medium storing a computer program. When the computer program is executed by a computer, the resistance measurement method as described above is implemented.

[0118] In addition, an embodiment of the present application further provides a computer program product, including a computer program. When the computer program is executed by a computer, the resistance measurement method as described above is implemented.

Claims

1. A thermistor resistance measurement circuit, characterized in that: include: A first resistor and a first switch are connected in series between a first node and a second node, wherein the first node is used to connect to a supply voltage; A second resistor and a second switch are connected in series between the first node and the second node in a manner of being connected in parallel with the first resistor and the first switch, wherein the resistance of the second resistor is smaller than that of the first resistor; a first switch transistor connected between the second node and a third node, wherein the third node is connected to a ground voltage via the thermistor; A fifth resistor, a second switch transistor and a sixth resistor are sequentially connected in series between the first node and the ground voltage; A first operational amplifier having a first non-inverting input terminal connected to a reference voltage, a first inverting input terminal connected between the second switch transistor and the sixth resistor, and a first output terminal connected to a gate of the second switch transistor; a second operational amplifier having a second non-inverting input terminal connected between the fifth resistor and the second switch transistor, a second inverting input terminal connected between the first resistor and the first switch and between the second resistor and the second switch, and a second output terminal connected to the gate of the first switch transistor; a detection unit having a detection terminal connected to the third node, the detection unit being used to detect a voltage across the thermistor and determine a resistance value of the thermistor according to the voltage across the thermistor; Determining the resistance value of the thermistor according to the voltage across the thermistor includes: When the first switch is turned on and the second switch is turned off, determining the resistance value of the thermistor based on formula (1); When the second switch is turned on and the first switch is turned off, determining the resistance value of the thermistor based on formula (2); Among them, R c is the resistance of the thermistor, Vc is the voltage across the thermistor, Vref is the reference voltage, R1 is the resistance of the first resistor, R2 is the resistance of the second resistor, R5 is the resistance of the fifth resistor, and R6 is the resistance of the sixth resistor.

2. The circuit according to claim 1, characterized in that Also includes: A third resistor and a third switch are connected in series between the first node and the second node in a manner of being connected in parallel with the first resistor and the first switch, wherein a resistance value of the third resistor is smaller than that of the second resistor; A fourth resistor and a fourth switch are connected in series between the first node and the second node in parallel with the first resistor and the first switch, wherein a resistance value of the fourth resistor is smaller than that of the third resistor.

3. The circuit according to claim 2, characterized in that The detection unit is also used for: When the third switch is turned on and the first switch, the second switch and the fourth switch are all turned off, the resistance value of the thermistor is determined based on formula (3); When the fourth switch is turned on and the first switch, the second switch and the third switch are all turned off, the resistance value of the thermistor is determined based on formula (4); Among them, R c is the resistance of the thermistor, Vc is the voltage across the thermistor, Vref is the reference voltage, R3 is the resistance of the third resistor, R4 is the resistance of the fourth resistor, R5 is the resistance of the fifth resistor, and R6 is the resistance of the sixth resistor.

4. The circuit according to any one of claims 1 to 3, characterized in that The first resistor and the first switch are sequentially connected in series between the first node and the second node, and the second resistor and the second switch are sequentially connected in series between the first node and the second node.

5. The circuit according to any one of claims 1 to 3, characterized in that The detection unit is further used to determine the temperature of the thermistor according to the resistance value of the thermistor.

6. The circuit according to any one of claims 1 to 3, characterized in that The detection unit comprises: A third operational amplifier having a third non-inverting input terminal, a third inverting input terminal and a third output terminal, wherein the third non-inverting input terminal constitutes the detection terminal, and the third inverting input terminal is connected to the third output terminal; The analog-to-digital converter is connected to the third output terminal and is used to convert the analog voltage signal provided by the third output terminal into a digital voltage signal.

7. A method for measuring the resistance of a thermistor, characterized in that: Applied to the circuit as claimed in any one of claims 1 to 6, the method comprising: In response to the supply voltage being greater than a threshold voltage, the first switch is controlled to be turned on and the second switch is turned off, and the resistance value of the thermistor is determined based on formula (1); In response to the supply voltage being less than the threshold voltage, controlling the second switch to be turned on and the first switch to be turned off, and determining the resistance value of the thermistor based on formula (2); Among them, R c is the resistance of the thermistor, Vc is the voltage across the thermistor, Vref is the reference voltage, R1 is the resistance of the first resistor, R2 is the resistance of the second resistor, R5 is the resistance of the fifth resistor, and R6 is the resistance of the sixth resistor.

8. A method for measuring the resistance of a thermistor, characterized in that: Applied to the circuit as claimed in claim 2 or 3, the method comprises: In response to the supply voltage being greater than a first threshold voltage, the first switch is controlled to be turned on, the second switch, the third switch and the fourth switch are all turned off, and the resistance value of the thermistor is determined based on formula (1); In response to the supply voltage being less than the first threshold voltage and greater than the second threshold voltage, the second switch is controlled to be turned on, the first switch, the third switch and the fourth switch are all turned off, and the resistance value of the thermistor is determined based on formula (2); In response to the supply voltage being less than the second threshold voltage and greater than a third threshold voltage, the third switch is controlled to be turned on, the first switch, the second switch and the third switch are all turned off, and the resistance value of the thermistor is determined based on formula (3); In response to the supply voltage being less than the third threshold voltage, the fourth switch is controlled to be turned on, the first switch, the second switch and the third switch are all turned off, and the resistance value of the thermistor is determined based on formula (4); Among them, R c is the resistance of the thermistor, Vc is the voltage across the thermistor, Vref is the reference voltage, R1 is the resistance of the first resistor, R2 is the resistance of the second resistor, R3 is the resistance of the third resistor, R4 is the resistance of the fourth resistor, R5 is the resistance of the fifth resistor, and R6 is the resistance of the sixth resistor.

9. A computer-readable storage medium, characterized in that: A computer program is stored, and when the computer program is executed by a computer, the method according to claim 7 or 8 is implemented.

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