A three-wire thermal resistance acquisition circuit and measurement circuit, electronic equipment

Abstract

The present application discloses a three-wire thermal resistor acquisition circuit and a measurement circuit, and an electronic device, wherein the three-wire thermal resistor acquisition circuit includes: a mirror image constant current source circuit, a proportional sampling circuit, a programmable operational amplifier circuit, and an analog-to-digital conversion circuit; the proportional sampling circuit is used to receive and obtain a proportional sampling voltage using a first mirror image current sent by the mirror image constant current source circuit; the programmable operational amplifier circuit obtains an operational amplification signal using an input differential voltage; wherein the input differential voltage is the voltage of the thermal resistor to be measured obtained by the three-wire thermal resistor receiving and using the first mirror image current and the second mirror image current sent by the mirror image constant current source circuit; the analog-to-digital conversion circuit is used to receive the proportional sampling voltage and the operational amplification signal, and convert the operational amplification signal into a digital measurement signal using the proportional sampling voltage. Through the above-mentioned method, the three-wire thermal resistor acquisition circuit in the present application can effectively improve the measurement accuracy of the three-wire thermal resistor, and the consistency is good.

Description

Technical Field

[0001] The present application relates to the technical field of electronic equipment, and in particular to a three-wire thermal resistor acquisition circuit and measurement circuit, and electronic equipment. Background Art

[0002] Nowadays, thermal resistance temperature measurement is widely used in industrial control. It is mainly used in temperature measurement and constant temperature control in the industrial field, especially in scenarios with strict temperature environment requirements, which require higher precision temperature measurement solutions.

[0003] However, the reference power supply voltage of the existing thermal resistor measurement circuit usually has voltage ripple, which greatly affects the measurement accuracy; and due to the line resistance of the three-wire thermal resistor, the measurement accuracy is also low and the consistency is poor in long-distance thermal resistor temperature measurement. Summary of the invention

[0004] The main technical problem solved by the present application is to provide a three-wire thermal resistor acquisition circuit and measurement circuit, and electronic equipment, which can solve the problem of low measurement accuracy and poor measurement consistency of the three-wire thermal resistor acquisition circuit in the prior art.

[0005] In order to solve the above technical problems, a technical solution adopted by the present application is: to provide a three-wire thermal resistor acquisition circuit, wherein the three-wire thermal resistor acquisition circuit includes: a mirror image constant current source circuit; a proportional sampling circuit, coupled to the mirror image constant current source circuit, and used to couple with the three-wire thermal resistor; a programmable operational amplifier circuit, coupled to the mirror image constant current source circuit and the proportional sampling circuit, and used to couple with the three-wire thermal resistor; an analog-to-digital conversion circuit, the analog-to-digital conversion circuit is coupled to the proportional sampling circuit and the programmable operational amplifier circuit, and is used to communicate with the signal processing circuit; wherein the proportional sampling circuit is used to receive the first mirror image current sent by the mirror image constant current source circuit, so as to obtain a proportional sampling voltage using the first mirror image current; the programmable operational amplifier circuit obtains an operational amplification signal using an input differential voltage; wherein the input differential voltage is the first mirror image current and the second mirror image current sent by the three-wire thermal resistor to receive the mirror image constant current source circuit, so as to obtain the thermal resistor voltage to be measured using the first mirror image current and the second mirror image current; the analog-to-digital conversion circuit is used to receive the proportional sampling voltage and the operational amplification signal, and convert the operational amplification signal into a digital measurement signal using the proportional sampling voltage to send to the signal processing circuit.

[0006] Among them, the mirror constant current source circuit has a first current output terminal and a second current output terminal, the proportional sampling circuit has a first sampling terminal and a second sampling terminal, the programmable operational amplifier circuit has a positive input terminal, a reverse input terminal, a ground terminal and an operational output terminal, the analog-to-digital conversion circuit has a positive reference voltage terminal, a negative reference voltage terminal, a conversion input terminal and a conversion output terminal, the first sampling terminal is coupled to the first current output terminal, the second sampling terminal is used to couple with the first terminal of the three-wire thermal resistor, the positive input terminal is coupled to the first sampling terminal, the reverse input terminal is coupled to the second current output terminal, and is used to couple with the second terminal of the three-wire thermal resistor, and the ground terminal is used to couple with the three-wire thermal resistor. The third end of the resistor is coupled, the positive reference voltage end is coupled to the first sampling end, the negative reference voltage end is coupled to the second sampling end, the conversion input end is coupled to the operation output end, and the conversion output end is used to communicate with the signal processing circuit; wherein, the first current output end is used to output the first mirror current to the proportional sampling circuit, and output it to the first end and the positive input end of the three-wire thermal resistor through the proportional sampling circuit, and the second current output end is used to output the second mirror current to the reverse input end and the second end of the three-wire thermal resistor, the first mirror current is the same as the second mirror current, and the input differential voltage is the product of the thermal resistance value of the three-wire thermal resistor and the first mirror current.

[0007] Among them, the three-wire thermal resistor acquisition circuit also includes a voltage boosting circuit, the first end of the voltage boosting circuit is used to couple with the third end of the three-wire thermal resistor, and the second end of the voltage boosting circuit is coupled to the ground end of the programmable operational amplifier circuit.

[0008] Among them, the three-wire thermal resistor acquisition circuit also includes a multi-channel switching circuit, which couples the second current output terminal, the second terminal of the proportional sampling circuit, the forward input terminal and the reverse input terminal, and is used to couple with at least two three-wire thermal resistors to selectively couple the first terminal and the second terminal of any one of the at least two three-wire thermal resistors to the second terminal and the second current output terminal of the proportional sampling circuit, respectively.

[0009] Among them, the multi-channel switching switch circuit includes a first switching switch sub-circuit and a second switching switch sub-circuit, the first switching switch sub-circuit is coupled to the second end of the proportional sampling circuit, and is used to couple with at least two three-wire thermal resistors to selectively couple the first end of any one of the at least two three-wire thermal resistors to the second end of the proportional sampling circuit; the second switching switch sub-circuit is coupled to the second current output end, and is used to couple with at least two three-wire thermal resistors to selectively couple the second end of any one of the at least two three-wire thermal resistors to the second current output end.

[0010] Among them, the multi-channel switching switch circuit also includes a third switching switch sub-circuit and a fourth switching switch sub-circuit. The third switching switch sub-circuit is coupled to the forward input terminal and is used to couple with at least two three-wire thermal resistors to selectively couple the first end of any one of the at least two three-wire thermal resistors to the forward input terminal; the fourth switching switch sub-circuit is coupled to the reverse input terminal and is used to couple with at least two three-wire thermal resistors to selectively couple the second end of any one of the at least two three-wire thermal resistors to the reverse input terminal.

[0011] Among them, the input voltage of the positive reference voltage terminal is not greater than the maximum sampling range voltage of the signal processing circuit; the input voltage of the positive reference voltage terminal is: V ref+ =(R ref +R k +R L1 +R TD )*i1+(R L3 +R r )*(i1+i2); where R ref is the equivalent resistance value of the proportional sampling circuit, R TD is the thermal resistance value, R L1 is the equivalent resistance value of the wire at end a of the three-wire thermal resistor, R L3 is the equivalent resistance value of the C-terminal wire of the three-wire thermal resistor, R r is the equivalent resistance value of the voltage boost circuit, R k is the equivalent resistance value of the multi-channel switching circuit, i1 is the first mirror current, and i2 is the second mirror current.

[0012] The three-wire thermal resistor acquisition circuit further includes a filter circuit, which is coupled between the operation output terminal and the conversion input terminal.

[0013] In order to solve the above technical problems, another technical solution adopted in the present application is: to provide a three-wire thermal resistor measurement circuit, wherein the three-wire thermal resistor measurement circuit includes a three-wire thermal resistor acquisition circuit and a signal processing circuit, and the three-wire thermal resistor acquisition circuit communicates with the signal processing circuit; wherein the three-wire thermal resistor acquisition circuit is a three-wire thermal resistor acquisition circuit as described in any of the above items.

[0014] To solve the above technical problems, another technical solution adopted in the present application is: to provide an electronic device, wherein the electronic device includes a shell and a signal function circuit connected to the shell; wherein the signal function circuit is a three-wire thermistor acquisition circuit as described in any of the above items, or a three-wire thermistor measurement circuit as described above.

[0015] The beneficial effects of the present application are as follows: Different from the prior art, the proportional sampling circuit in the three-wire thermal resistor acquisition circuit provided by the present application is used to receive the first mirror current sent by the mirror constant current source circuit, so as to obtain the proportional sampling voltage by using the first mirror current, and the programmable operational amplifier circuit obtains the operational amplifier signal by using the input differential voltage, and the input differential voltage is specifically the first mirror current and the second mirror current sent by the mirror constant current source circuit received by the three-wire thermal resistor, so as to obtain the voltage of the thermal resistor to be measured by using the first mirror current and the second mirror current, and the analog-to-digital conversion circuit is used to receive the proportional sampling voltage and the operational amplifier signal, and convert the operational amplifier signal into a digital measurement signal by using the proportional sampling voltage, so as to send it to the signal processing circuit to realize the temperature measurement calculation, so that the voltage at both ends of the proportional sampling circuit can be applied to the analog-to-digital conversion circuit, and an equipotential can be formed to eliminate the error caused by the ripple of the reference power supply voltage of the analog-to-digital conversion circuit, thereby effectively improving the measurement accuracy of the three-wire thermal resistor; and the output of the first mirror current and the second mirror current to the three-wire thermal resistor by the mirror constant current source circuit also effectively offsets the influence of the line resistance of the three-wire thermal resistor on the measurement, and effectively ensures the measurement accuracy and consistency in the long-distance thermal resistor temperature measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0017] Figure 1 It is a structural schematic diagram of the first implementation mode of the three-wire thermal resistance acquisition circuit of the present application;

[0018] Figure 2 It is a structural schematic diagram of the second implementation mode of the three-wire thermal resistance acquisition circuit of the present application;

[0019] Figure 3 It is a structural schematic diagram of the third implementation mode of the three-wire thermal resistance acquisition circuit of the present application;

[0020] Figure 4 It is a structural schematic diagram of an implementation method of a three-wire thermal resistance measurement circuit of the present application;

[0021] Figure 5 It is a schematic structural diagram of an embodiment of an electronic device of the present application. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] The terms "first", "second" and "third" in this application are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second" and "third" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. All directional indications (such as up, down, left, right, front, back...) in the implementation mode of this application are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices.

[0024] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] The present application is described in detail below with reference to the accompanying drawings and implementation methods.

[0026] See also Figure 1 , Figure 1 The schematic diagram is a schematic diagram of the structure of the first embodiment of the three-wire thermal resistor acquisition circuit of the present application. In this embodiment, the three-wire thermal resistor acquisition circuit 10 includes: a mirror constant current source circuit 11, a proportional sampling circuit 12, a programmable operational amplifier circuit 13 and an analog-to-digital conversion circuit 14.

[0027] Among them, a three-wire thermal resistor acquisition circuit 10 provided in the present application is specifically used in the temperature measurement of thermal resistors, especially in scenes with strict requirements on temperature environment, such as wave soldering, reflow soldering, blister machines, patch machines, lithium batteries, chip manufacturing industrial control and other industrial fields, so as to obtain corresponding temperature parameters by measuring and calculating the voltage of the three-wire thermal resistor 101. Of course, in other embodiments, the three-wire thermal resistor acquisition circuit 10 can also be specifically applied to temperature measurement and constant temperature control in lithium batteries, chip production, and other any other reasonable industrial fields with high requirements on the accuracy of temperature control, and this embodiment is not limited to this.

[0028] It is worth noting that the mirror image constant current source is a standard component commonly found in analog integrated circuits, and its controlled current is equal to the input reference current, that is, the input-output current transfer ratio is equal to 1. Its characteristic is that the output current is a "copy" of the input current in a certain proportion, which is used to generate bias current and serve as an active load.

[0029] The working principle of the three-wire thermal resistor 101 is mainly to reduce the influence of wire resistance on temperature measurement through a specific wiring method, thereby improving the measurement accuracy. Specifically, the wiring method: the three-wire thermal resistor 101 uses three wires, one of which is connected in series to the power supply of the bridge, and the other two are connected in series to the adjacent arms of the bridge. This wiring method increases the resistance of the two adjacent arms, helps to balance the bridge, and reduces the influence of wire resistance on temperature measurement.

[0030] In addition, the term "coupled" herein refers to any direct and indirect connection means. Therefore, if the first circuit is described as being coupled to the second circuit, it means that the first circuit can be directly connected to the second circuit through electrical connection or signal connection methods such as wireless transmission, optical transmission, etc., or can be indirectly connected to the second circuit through other circuits or connection means.

[0031] Specifically, the proportional sampling circuit 12 is coupled to the mirror constant current source circuit 11 and is used to couple with the three-wire thermal resistor 101; the programmable operational amplifier circuit 13 is coupled to the mirror constant current source circuit 11 and the proportional sampling circuit 12 and is used to couple with the three-wire thermal resistor 101; the analog-to-digital conversion circuit 14 is coupled to the proportional sampling circuit 12 and the programmable operational amplifier circuit 13 and is used to communicate with the signal processing circuit 102.

[0032] The proportional sampling circuit 12 is used to receive the first mirror current sent by the mirror constant current source circuit 11. The mirror constant current source circuit 11 can be understood as a circuit for providing a stable current for exciting the thermal resistor. After receiving the first mirror current, the proportional sampling circuit 12 will generate a voltage signal proportional to the first mirror current according to its proportional characteristics, that is, a proportional sampling voltage.

[0033] The programmable operational amplifier circuit 13 receives a differential voltage signal, which comes from the voltage difference between the two ends of the actual thermal resistor of the three-wire thermal resistor 101, that is, the thermal resistor voltage to be measured. The programmable operational amplifier circuit 13 specifically obtains a stronger signal, that is, the operational amplification signal, by amplifying the differential voltage, that is, inputting the differential voltage. The programmable feature means that the amplification factor can be set by software or hardware to adapt to different thermal resistor types or measurement requirements.

[0034] The three-wire thermal resistor 101 is used to receive the first mirror current and the second mirror current sent by the mirror constant current source circuit 11, and reflect the temperature change by measuring the voltage difference generated by the first mirror current and the second mirror current at both ends of the actual thermal resistor, that is, the voltage of the thermal resistor to be measured.

[0035] The analog-to-digital conversion circuit 14 receives the proportional sampling voltage from the proportional sampling circuit 12 and the operational amplification signal from the programmable operational amplifier circuit 13, and converts the analog operational amplification signal into a digital signal, i.e., a digital measurement signal, by using the proportional sampling voltage, and sends the digital measurement signal to the signal processing circuit 102. This digital signal contains quantitative information about the temperature of the thermal resistor, and can be further processed and interpreted by the signal processing circuit 102 to obtain corresponding temperature information.

[0036] It is understandable that the three-wire thermal resistor acquisition circuit 10 achieves high-precision measurement of the thermal resistor temperature through precise current control, voltage sampling, signal amplification and analog-to-digital conversion. The proportional sampling circuit 12 and the programmable operational amplifier circuit 13 ensure the accuracy and stability of the signal, while the analog-to-digital conversion circuit 14 converts the analog signal into a form that is convenient for digital processing, so that the temperature data can be read and analyzed by a computer or microcontroller. This design is widely used in occasions that require high-precision temperature measurement, such as industrial automation, scientific research, medical equipment and other fields.

[0037] The above scheme applies the voltage across the proportional sampling circuit 12 to the analog-to-digital conversion circuit 14 and forms an equipotential to eliminate the error caused by the reference power supply voltage ripple of the analog-to-digital conversion circuit 14, thereby effectively improving the measurement accuracy of the three-wire thermal resistor 101; and the output of the first mirror current and the second mirror current to the three-wire thermal resistor 101 by the mirror constant current source circuit 11 also effectively offsets the influence of the line resistance of the three-wire thermal resistor 101 on the measurement, and effectively ensures the measurement accuracy and consistency in the long-distance thermal resistor temperature measurement.

[0038] In one embodiment, the mirror constant current source circuit 11 further has a first current output terminal and a second current output terminal, the proportional sampling circuit 12 has a first sampling terminal and a second sampling terminal, the programmable operational amplifier circuit 13 has a positive input terminal, a reverse input terminal, a ground terminal and an operational output terminal, and the analog-to-digital conversion circuit 14 has a positive reference voltage terminal, a negative reference voltage terminal, a conversion input terminal and a conversion output terminal.

[0039] And the first sampling end is specifically coupled to the first current output end, and the second sampling end is used to couple with the first end of the three-wire thermal resistor 101, the positive input end is coupled to the first sampling end, the reverse input end is coupled to the second current output end, and is used to couple with the second end of the three-wire thermal resistor 101, the ground end is used to couple with the third end of the three-wire thermal resistor 101, the positive reference voltage end is coupled to the first sampling end, the negative reference voltage end is coupled to the second sampling end, the conversion input end is coupled to the operation output end, and the conversion output end is used to communicate with the signal processing circuit 102.

[0040] Among them, the first current output end is specifically used to output the first mirror current provided by the mirror constant current source circuit 11 to the proportional sampling circuit 12, and output it to the first end of the three-wire thermal resistor 101 and the positive input end of the programmable operational amplifier circuit 13 through the proportional sampling circuit 12, and the second current output end is used to output the second mirror current provided by the mirror constant current source circuit 11 to the reverse input end of the programmable operational amplifier circuit 13 and the second end of the three-wire thermal resistor 101.

[0041] And the first mirror current is specifically the same as the second mirror current, so that when it is output to the first end and the second end of the three-wire thermal resistor 101 respectively, it can offset the line resistance of the three-wire thermal resistor 101, so that the input differential voltage of the programmable operational amplifier circuit 13, that is, the voltage between the positive input end and the reverse input end corresponds to the product of the thermal resistance value of the three-wire thermal resistor 101 and the first mirror current, so that in long-distance testing, the consistency of the thermal resistor temperature measurement can be effectively guaranteed, and it will not be affected by the line resistance of the three-wire thermal resistor 101, so as to achieve higher measurement accuracy.

[0042] It should be pointed out that the above-mentioned first mirror current and second mirror current being the same actually means that the two are theoretically the same. In actual application scenarios, the difference between the first mirror current and the second mirror current can be within a specific error range, and the error range can be adjusted according to the actual measurement accuracy requirements. This application does not limit this.

[0043] In addition, since the voltage between the positive reference voltage terminal and the negative reference voltage terminal of the analog-to-digital conversion circuit 14 corresponds to the voltage between the first sampling terminal and the second sampling terminal of the proportional sampling circuit 12, an equal potential is formed, which can effectively eliminate the error caused by the ripple of the reference power supply voltage of the analog-to-digital conversion circuit 14, thereby effectively improving the measurement accuracy of the three-wire thermal resistor 101.

[0044] When the first mirror current and the second mirror current increase synchronously, the operational amplification signal outputted by the programmable operational amplifier circuit 13 to the analog-to-digital conversion circuit 14 will increase accordingly, and the voltage between the first sampling terminal and the second sampling terminal of the proportional sampling circuit 12 will also increase, thereby increasing the full-scale reference voltage of the analog-to-digital conversion circuit 14. Therefore, the increase or decrease of the first mirror current and the second mirror current outputted by the mirror constant current source circuit 11 will not affect the measurement result of the analog-to-digital conversion circuit 14, thereby effectively achieving a higher measurement accuracy. The voltage between the positive input terminal and the reverse input terminal of the programmable operational amplifier circuit 13, i.e., the input differential voltage, is not affected by the change in the magnitude of the first mirror current and the second mirror current, nor by the change in the internal resistance of the line length of the three-wire thermal resistor 101, and has high measurement accuracy.

[0045] For ease of understanding, the first mirror current is i1, the second mirror current is i2, and the thermal resistance value of the three-wire thermal resistor 101 is R r The three-terminal resistances of the three-wire thermal resistor 101 are R L1 , R L2 , R L3 For example, it can be known that the specific formula of the thermal resistor voltage to be measured is as follows: the positive input terminal voltage of the programmable operational amplifier circuit 13 is:

[0046] V PGA +=R L1 *i1+R TD +i1+R L3 *(i1+i2)+R r *(i1+i2);

[0047] Since i1≈i2;

[0048] So: V PGA +=(R L1 +R TD +2R L3 +2R r )*i1;

[0049] The voltage at the positive input terminal and the voltage at the reverse input terminal of the programmable operational amplifier circuit 13 are:

[0050] V PGA -=R L2 *i1+RL3 *(i1+i2)+R r *(i1+i2);

[0051] Since i1≈i2;

[0052] So: V PGA -=(R L2 +2R L3 *+2R r )*i1;

[0053] Since the three-terminal line resistance R of the three-wire thermal resistor 101 L1 ≈R L2 ≈R L3 ;

[0054] The input differential voltage of the programmable operational amplifier circuit 13 is:

[0055] V PGA =(V PGA +)-(V PGA -)=(R L1 +R TD +2R L3 +2R r )*i1-(R L2 +2R L3 *+2R r )*i1=R TD *i1.

[0056] Among them, the voltage of the thermal resistor to be measured is the above V PGA , that is, R TD *i1; and the line resistances of the three-wire thermal resistor 101 are offset; since the proportional sampling circuit 12 is proportional, the current flowing through the proportional sampling circuit 12 is also i1, so the change in the current size of i1 does not affect the actual test value, that is, the voltage of the thermal resistor to be tested. In fact, the voltage to be tested is R TD The equivalent resistance R of the proportional sampling circuit 12 ref The ratio between the two, and the resistance of the equivalent resistor is R ref It is fixed, so the actual measured temperature value corresponding to the thermal resistance temperature curve can be calculated.

[0057] It is understandable that the two mirror image constant current outputs of the mirror image constant current source circuit 11, namely the first mirror image current i1 and the second mirror image current i2, will offset the three-terminal line resistance R of the three-wire thermal resistor 101. L1 , R L2 , R L3In long-distance testing, the measurement consistency will be maintained and the resistance value will not be affected by the line resistance; and the key is that the first mirror current i1 and the second mirror current i2 need to be consistent, and do not need to correspond to any reasonable and accurate current such as 1mA, 1.5mA4 or 2mA. This is the advantage of the proportional type. When the first mirror current i1 and the second mirror current i2 increase synchronously, the voltage value flowing through the proportional resistor also increases, thereby increasing the full-scale reference voltage of the analog-to-digital conversion circuit 14.

[0058] It can be seen that the increase or decrease of the first mirror current i1 and the second mirror current i2 does not affect the measurement result, but the magnitude of the first mirror current i1 and the second mirror current i2 must be consistent, which is easier to meet with a mirror current source, so high precision can be effectively achieved. The input differential voltage between the positive input terminal and the reverse input terminal of the programmable operational amplifier circuit 13 will not be affected by the change in the magnitude of the first mirror current i1 and the second mirror current i2 and the change in the line length internal resistance of the three-wire thermal resistor 101, further improving the measurement accuracy.

[0059] See also Figure 2 , Figure 2 This is a schematic diagram of the structure of the second embodiment of the three-wire thermal resistor acquisition circuit of the present application. This embodiment is based on the first embodiment of the three-wire thermal resistor acquisition circuit provided in the present application, and the three-wire thermal resistor acquisition circuit 20 specifically further includes a voltage boosting circuit 25.

[0060] Specifically, a first terminal of the voltage boosting circuit 25 is coupled to the third terminal of the three-wire thermal resistor 101 , and a second terminal of the voltage boosting circuit 25 is coupled to the ground terminal of the programmable operational amplifier circuit 23 .

[0061] It is understandable that since the positive input and the negative input of the programmable operational amplifier circuit 23 are not allowed to flow with current, that is, the positive input and the negative input are equivalent to high input resistance, so that the current flowing into the positive input and the negative input of the programmable operational amplifier circuit 23 is close to zero, and the input is equivalent to virtual disconnection. Therefore, the minimum input voltage of the negative input terminal needs to be maintained above 0V, and the voltage of the negative input terminal of the programmable operational amplifier circuit 23 needs to be effectively increased by the voltage boosting circuit 25 to prevent the negative input terminal of the programmable operational amplifier circuit 23 from inputting a small voltage cutoff, so as to achieve high-precision input.

[0062] In one embodiment, the three-wire thermal resistor acquisition circuit 20 specifically also includes a multi-channel switching circuit 26, which is coupled to the second current output terminal, the second terminal of the proportional sampling circuit 22, the forward input terminal and the reverse input terminal, and is used to couple with at least two three-wire thermal resistors 101.

[0063] Among them, the multi-channel switching switch circuit 26 can specifically selectively couple the first end and the second end of any one of at least two three-wire thermal resistors 101 to the second end and the second current output end of the proportional sampling circuit 22 by adjusting the connection method of different connection channels inside it, so that the mirror constant current source circuit 21 can input the first mirror current and the second mirror current to the first end and the second end of the corresponding three-wire thermal resistor 101 respectively through the path currently selectively connected by the multi-channel switching switch circuit 26, so as to realize voltage measurement of the three-wire thermal resistor 101, and then realize temperature measurement calculation; and by switching the connections between different paths of the multi-channel switching switch circuit 26, multi-point acquisition can be effectively realized, with low cost and strong scalability.

[0064] It is worth noting that the multi-channel switching circuit 26 can also be specifically communicatively connected to the signal processing circuit 102 to receive the control signal sent by the signal processing circuit 102, and realize switching between different channels under the action of the control signal to realize measurement of different three-wire thermal resistors 101; and in other embodiments, the multi-channel switching circuit 26 can also be manually switched between different channels by the user, and the present application does not limit this.

[0065] In one embodiment, the multi-channel switching circuit 26 further includes a first switching sub-circuit 261 and a second switching sub-circuit 262 . The first switching sub-circuit 261 is coupled to the second end of the proportional sampling circuit 22 and is used to couple to at least two three-wire thermal resistors 101 .

[0066] Among them, the first switching switch subcircuit 261 can specifically include a first common terminal and at least two first connection terminals, the first common terminal is connected to the second terminal of the proportional sampling circuit 22, and each first connection terminal is correspondingly connected to the first end of a three-wire thermal resistor 101; and the first switching switch subcircuit 261 can selectively connect the first common terminal to one of the first connection terminals in response to the control signal sent by the signal processing circuit 102 or the manual operation of the user, so as to selectively couple the first end of any one of the at least two three-wire thermal resistors 101 to the second end of the proportional sampling circuit 22.

[0067] Similarly, the second switching switch sub-circuit 262 is coupled to the second current output terminal of the mirror constant current source circuit 21, and is used to couple with at least two three-wire thermal resistors 101, and the second switching switch sub-circuit 262 may specifically include a second common terminal and at least two second connection terminals, the second common terminal is connected to the second current output terminal, and each second connection terminal is correspondingly connected to the second end of a three-wire thermal resistor 101; the second switching switch sub-circuit 262 specifically selectively connects the second common terminal to one of the second connection terminals in response to the control signal sent by the signal processing circuit 102 or the manual operation of the user, so as to selectively couple the second end of any one of the at least two three-wire thermal resistors 101 to the second end of the proportional sampling circuit 22.

[0068] It is worth noting that the first connection end of the first switching switch subcircuit 261 and the second connection end of the second switching switch subcircuit 262 are specifically the same three-wire thermal resistor 101 that is selectively connected in response to the control signal sent by the signal processing circuit 102 or the manual operation of the user. That is, when measuring different three-wire thermal resistors 101, the first switching switch subcircuit 261 and the second switching switch subcircuit 262 are switched and controlled synchronously to cooperate with each other to realize the voltage measurement of different three-wire thermal resistors 101.

[0069] In one embodiment, the input voltage of the positive reference voltage terminal is not greater than the maximum sampling range voltage of the signal processing circuit 102; and the input voltage of the positive reference voltage terminal can be specifically: V ref+ =(R ref +R k +R L1 +R TD )*i1+(R L3 +R r )*(i1+i2); where R ref is the equivalent resistance value of the proportional sampling circuit 22, R TD is the thermal resistance value, R L1 is the equivalent resistance value of the wire at end a of the three-wire thermal resistor 101, R L3 is the equivalent resistance value of the C-terminal wire of the three-wire thermal resistor 101, R r is the equivalent resistance value of the voltage boosting circuit 25, R k is the equivalent resistance value of the multi-channel switching circuit 26, i1 is the first mirror current, and i2 is the second mirror current.

[0070] Specifically, since the maximum voltage value of the positive reference voltage terminal of the analog-to-digital conversion circuit 24 cannot exceed the maximum voltage of the sampling range of the signal processing circuit 102, the constraint condition of the analog-to-digital conversion circuit 24 is as follows:

[0071] Vref+ =(R ref +R k +R L1 +R TD )*i1+(R L3 +R r )*(i1+i2);

[0072] Since the first mirror current i1 and the second mirror current i2 are mirror constant current sources i1≈i2; therefore, V ref+ =(R ref +R k +R L1 +R TD +2R L3 +2R r )*i1,V ref+ The voltage cannot exceed the maximum voltage that the proportional sampling circuit 22 can collect for mass production.

[0073] In one embodiment, the three-wire thermal resistor acquisition circuit 20 specifically also includes a filtering circuit (not shown), which is coupled between the operational output terminal and the conversion input terminal of the programmable operational amplifier circuit 23, and is used to filter the operational amplified signal of the operational output terminal and send it to the analog-to-digital conversion circuit 24, so that the digital conversion circuit uses the proportional sampling voltage to convert the filtered operational amplified signal into a digital measurement signal, which is sent to the signal processing circuit 102, thereby effectively improving the voltage measurement accuracy of the overall three-wire thermal resistor 101.

[0074] It is understandable that, in this embodiment, the mirror image constant current source circuit 21, the proportional sampling circuit 22, the programmable operational amplifier circuit 23 and the analog-to-digital conversion circuit 24 are respectively the same as the mirror image constant current source circuit 11, the proportional sampling circuit 12, the programmable operational amplifier circuit 13 and the analog-to-digital conversion circuit 14. For details, please refer to Figure 1 And the related text content will not be repeated here.

[0075] See also Figure 3 , Figure 3 1 is a schematic diagram of the structure of the third embodiment of the three-wire thermal resistor acquisition circuit of the present application. The difference between the three-wire thermal resistor acquisition circuit in this embodiment and the second embodiment of the three-wire thermal resistor acquisition circuit provided by the present application is that the multi-channel switching switch circuit 36 ​​in the three-wire thermal resistor acquisition circuit 30 specifically further includes a third switching switch sub-circuit 363 and a fourth switching switch sub-circuit 364.

[0076] Specifically, the third switching switch sub-circuit 363, that is, the third switching switch sub-circuit SK3 is coupled to the programmable operational amplifier circuit 33, that is, the positive input terminal of the programmable operational amplifier circuit PGA, and is used to couple with at least two three-wire thermal resistors 101. The fourth switching switch sub-circuit 364, that is, the fourth switching switch sub-circuit SK4 is coupled to the reverse input terminal of the programmable operational amplifier circuit 33, and is used to couple with at least two three-wire thermal resistors 101.

[0077] Among them, the third switching switch sub-circuit 363 can specifically include a third common terminal and at least two third connection terminals, the third common terminal is connected to the positive input terminal, and each third connection terminal is correspondingly connected to the first end of a three-wire thermal resistor 101; and the third switching switch sub-circuit 363 can selectively connect the third common terminal with one of the third connection terminals in response to the control signal sent by the signal processing circuit 102 or the manual operation of the user, so as to selectively couple the first end of any one of the at least two three-wire thermal resistors 101 to the positive input terminal.

[0078] Similarly, the fourth switching switch subcircuit 364 may specifically include a fourth common terminal and at least two fourth connection terminals, the fourth common terminal being connected to the reverse input terminal, and each fourth connection terminal being correspondingly connected to the second end of a three-wire thermal resistor 101; and the fourth switching switch subcircuit 364 can selectively connect the fourth common terminal to one of the fourth connection terminals in response to a control signal correspondingly sent by the signal processing circuit 102 or a manual operation of the user, so as to selectively couple the second end of any one of the at least two three-wire thermal resistors 101 to the reverse input terminal.

[0079] It is worth noting that the third connection terminal of the third switching switch subcircuit 363 and the fourth connection terminal of the fourth switching switch subcircuit 364 are specifically the same three-wire thermal resistor 101 selectively connected in response to the control signal sent by the signal processing circuit 102 or the manual operation of the user, and the three-wire thermal resistor 101 selectively connected to the first switching switch subcircuit 361, that is, the first connection terminal of the first switching switch subcircuit SK1 and the second switching switch subcircuit 362, that is, the second connection terminal of the second switching switch subcircuit SK2 are also the same; when measuring different three-wire thermal resistors 101, specifically The first switching switch subcircuit 361, the second switching switch subcircuit 362, the third switching switch subcircuit 363 and the fourth switching switch subcircuit 364 are synchronously switched and controlled to cooperate with each other to realize the voltage measurement of different three-wire thermal resistors 101; and in specific scenarios, the third switching switch subcircuit 363 and the fourth switching switch subcircuit 364 can be used to realize open-circuit control between the mirror constant current source circuit 31 and the programmable operational amplifier circuit 33, effectively avoiding current input to the positive input terminal and the reverse input terminal of the programmable operational amplifier circuit 33, so as to prevent the reverse input terminal from inputting a small voltage cutoff, thereby achieving high-precision input.

[0080] In addition, since the first switching switch sub-circuit 361 is outside the proportional sampling circuit 32, its equivalent internal resistance will not affect the accuracy of the equivalent resistance of the proportional sampling circuit 32; and the positive input terminal and the reverse input terminal are virtual disconnected, the equivalent internal resistance of the second switching switch sub-circuit 362, the third switching switch sub-circuit 363 and the fourth switching switch sub-circuit 364 will not affect the measurement accuracy of the three-wire thermal resistor 101.

[0081] It can be understood that in the present embodiment, four three-wire thermal resistors 101 are specifically shown, and the first switching switch subcircuit 361 specifically includes four first connection terminals; similarly, the second switching switch subcircuit 362 specifically includes four second connection terminals, the third switching switch subcircuit 363 specifically includes four first connection terminals, and the fourth switching switch subcircuit 364 specifically includes four fourth connection terminals, so as to respectively connect to the second terminals of the four three-wire thermal resistors 101, and selectively measure different three-wire thermal resistors 101 in response to the control signal sent by the signal processing circuit 102 or the manual operation of the user.

[0082] In other embodiments, the three-wire thermal resistor acquisition circuit 30 is intended to achieve that the number of connected three-wire thermal resistors 101 can be any reasonable number such as 3, 5 or 6, and they are arranged at different positions in the corresponding electronic device to meet the temperature measurement needs of more scenarios. This application does not limit this.

[0083] Optionally, the first switching switch subcircuit 361, the second switching switch subcircuit 362, the third switching switch subcircuit 363 and the fourth switching switch subcircuit 364 can specifically be a single-pole multi-throw switch, or a relay with multiple normally open and normally closed contacts, or any other reasonable circuit element with multiple selectable paths, and preferably a relay, which is not limited in the present application.

[0084] In other embodiments, the third switching switch subcircuit 363 and the fourth switching switch subcircuit 364 can be replaced by short-circuit wires, and the first switching switch subcircuit 361 and the second switching switch subcircuit 362 correspond to any reasonable circuit elements with multiple selectable paths, such as single-pole multi-throw switches or relays, and the present application does not limit this.

[0085] Optionally, the proportional sampling circuit 32 may specifically include a proportional resistor R b , or a circuit unit composed of any reasonable circuit elements such as resistors, inductors, capacitors, etc., which are interconnected, and this application does not limit this.

[0086] Optionally, the voltage boosting circuit 25 may specifically include a boosting resistor R s , or a circuit unit composed of any reasonable circuit elements such as resistors, inductors, capacitors, etc., which are interconnected, and this application does not limit this.

[0087] Optionally, the signal processing circuit 102 may specifically include an MCU (Micro Control Unit) circuit, a CPU (Central Processing Unit), a single-chip microcomputer, a field programmable gate array, a programmable logic device, a discrete gate or transistor logic device, discrete hardware, or any other reasonable circuit unit used to form a program and signal processing function. This application does not limit this.

[0088] Through the above scheme, the three-wire thermal resistor acquisition circuit has the advantages of high-precision acquisition, multi-channel and multi-point acquisition, strong channel consistency, no influence of line length, good measurement consistency, etc.; and the proportional sampling method can offset the influence of the ripple fluctuation of the reference power supply voltage of the analog-to-digital conversion circuit 34, and can effectively achieve high precision; multi-channel switching can acquire data at multiple points, with low cost and strong scalability; in addition, the two outputs of the mirror constant current source circuit 31 can effectively offset the line resistance of the three-wire thermal resistor 101, so that in long-distance testing, the consistency and resistance value can be maintained without being affected by the line resistance.

[0089] It is understandable that, in this embodiment, the mirror image constant current source circuit 31, the programmable operational amplifier circuit 33 and the analog-to-digital conversion circuit 34 are respectively the same as the mirror image constant current source circuit 21, the programmable operational amplifier circuit 22 and the analog-to-digital conversion circuit 24. For details, please refer to Figure 2 And the related text content will not be repeated here.

[0090] This application also provides a three-wire thermal resistance measurement circuit, see Figure 4 , Figure 4 The three-wire thermal resistor measurement circuit 40 is a schematic diagram of an embodiment of the present invention. In this embodiment, the three-wire thermal resistor measurement circuit 40 includes: a three-wire thermal resistor acquisition circuit 41 and a signal processing circuit 42. The three-wire thermal resistor acquisition circuit 41 is connected to the signal processing circuit 42 in communication.

[0091] It should be noted that the three-wire thermal resistor acquisition circuit 41 described in this embodiment is the three-wire thermal resistor acquisition circuit 10, the three-wire thermal resistor acquisition circuit 20 or the three-wire thermal resistor acquisition circuit 30 described in any one of the above embodiments. Figure 1-3 And the related text content will not be repeated here.

[0092] This application also provides an electronic device, see Figure 5 , Figure 5 1 is a schematic diagram of the structure of an electronic device of the present application. In this embodiment, the electronic device 50 includes a housing 51 and a signal function circuit 52 connected to the housing 51 .

[0093] Optionally, the electronic device 50 can be a temperature measuring device of any reasonable electronic mechanical device such as a reflow soldering device, a blister machine, a lithium battery production device, or a chip production device, and the present application does not limit this.

[0094] It should be noted that the signal function circuit 52 described in this embodiment is the three-wire thermal resistor acquisition circuit 10, the three-wire thermal resistor acquisition circuit 20 or the three-wire thermal resistor acquisition circuit 30, or the three-wire thermal resistor measurement circuit 40 described in any one of the above embodiments. Figure 1-4 And the related text content will not be repeated here.

[0095] The beneficial effects of the present application are as follows: Different from the prior art, the proportional sampling circuit provided by the present application is used to receive the first mirror current sent by the mirror constant current source circuit, so as to obtain the proportional sampling voltage by using the first mirror current, the programmable operational amplifier circuit obtains the operational amplification signal by using the input differential voltage, and the input differential voltage is specifically the first mirror current and the second mirror current sent by the mirror constant current source circuit received by the three-wire thermal resistor, so as to obtain the voltage of the thermal resistor to be measured by using the first mirror current and the second mirror current, the analog-to-digital conversion circuit is used to receive the proportional sampling voltage and the operational amplification signal, and convert the operational amplification signal into a digital measurement signal by using the proportional sampling voltage, so as to send it to the signal processing circuit to realize the temperature measurement calculation, so that the error caused by the ripple of the reference power supply voltage of the analog-to-digital conversion circuit can be eliminated by applying the voltage at both ends of the proportional sampling circuit to the analog-to-digital conversion circuit and forming an equipotential, thereby effectively improving the measurement accuracy of the three-wire thermal resistor; and the output of the first mirror current and the second mirror current to the three-wire thermal resistor by the mirror constant current source circuit also effectively offsets the influence of the line resistance of the three-wire thermal resistor on the measurement, and effectively ensures the measurement accuracy and consistency in the long-distance thermal resistor temperature measurement.

[0096] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A three-wire thermal resistance acquisition circuit, characterized in that: The three-wire thermal resistance acquisition circuit comprises: A mirror image constant current source circuit has a first current output terminal and a second current output terminal; A proportional sampling circuit, comprising a first sampling terminal and a second sampling terminal, wherein the first sampling terminal is coupled to the first current output terminal, and the second sampling terminal is used to couple to a first terminal of a three-wire thermal resistor; A programmable operational amplifier circuit, comprising a positive input terminal, a negative input terminal, a ground terminal and an operational output terminal, wherein the positive input terminal is coupled to the first sampling terminal, the negative input terminal is coupled to the second current output terminal and is used to couple with the second terminal of the three-wire thermal resistor, and the ground terminal is used to couple with the third terminal of the three-wire thermal resistor; An analog-to-digital conversion circuit, comprising a positive reference voltage terminal, a negative reference voltage terminal, a conversion input terminal and a conversion output terminal, wherein the positive reference voltage terminal is coupled to the first sampling terminal, the negative reference voltage terminal is coupled to the second sampling terminal, the conversion input terminal is coupled to the operation output terminal, and the conversion output terminal is used for communication connection with a signal processing circuit; A multi-channel switching switch circuit, comprising a first switching switch subcircuit, a second switching switch subcircuit, a third switching switch subcircuit and a fourth switching switch subcircuit, wherein the first switching switch subcircuit is coupled to the second end of the proportional sampling circuit and is used to couple with at least two of the three-wire thermal resistors to selectively couple the first end of any one of the at least two three-wire thermal resistors to the second end of the proportional sampling circuit; the second switching switch subcircuit is coupled to the second current output end and is used to couple with at least two of the three-wire thermal resistors to selectively couple the first end of any one of the three-wire thermal resistors to the second end of the proportional sampling circuit. The second end of any one of at least two of the three-wire thermal resistors is coupled to the second current output end; the third switching switch subcircuit is coupled to the positive input end, and is used to couple with at least two of the three-wire thermal resistors to selectively couple the first end of any one of the at least two of the three-wire thermal resistors to the positive input end; the fourth switching switch subcircuit is coupled to the reverse input end, and is used to couple with at least two of the three-wire thermal resistors to selectively couple the second end of any one of the at least two of the three-wire thermal resistors to the reverse input end; The proportional sampling circuit is used to receive the first mirror current sent by the mirror constant current source circuit, so as to obtain a proportional sampling voltage using the first mirror current; The programmable operational amplifier circuit uses the input differential voltage to obtain an operational amplifier signal; wherein the input differential voltage is the voltage of the thermal resistor to be measured obtained by the three-wire thermal resistor receiving the first mirror current and the second mirror current sent by the mirror constant current source circuit, and using the first mirror current and the second mirror current; The analog-to-digital conversion circuit is used to receive the proportional sampling voltage and the operational amplification signal, and convert the operational amplification signal into a digital measurement signal using the proportional sampling voltage to send to the signal processing circuit; The first current output end is used to output the first mirror current to the proportional sampling circuit, and output it to the first end and the forward input end of the three-wire thermal resistor through the proportional sampling circuit. The second current output end is used to output the second mirror current to the reverse input end and the second end of the three-wire thermal resistor. The first mirror current is the same as the second mirror current, and the input differential voltage is the product of the thermal resistance value of the three-wire thermal resistor and the first mirror current.

2. The three-wire thermal resistance acquisition circuit according to claim 1 is characterized in that: The three-wire thermal resistor acquisition circuit also includes a voltage boosting circuit, a first end of the voltage boosting circuit is used to couple with the third end of the three-wire thermal resistor, and a second end of the voltage boosting circuit is coupled to the ground end of the programmable operational amplifier circuit.

3. The three-wire thermal resistance acquisition circuit according to claim 2 is characterized in that: The input voltage of the positive reference voltage terminal is not greater than the maximum sampling range voltage of the signal processing circuit; The input voltage of the positive reference voltage terminal is: V ref+ =(R ref +R k +R L1 +R TD )*i1+(R L3 +R r )*(i1+i2); Among them, R ref is the equivalent resistance value of the proportional sampling circuit, R TD is the thermal resistance value, R L1 is the equivalent resistance value of the wire at end a of the three-wire thermal resistor, R L3 is the equivalent resistance value of the wire at the C end of the three-wire thermal resistor, R r is the equivalent resistance value of the voltage boost circuit, R k is the equivalent resistance value of the multi-channel switching circuit, i1 is the first mirror current, and i2 is the second mirror current.

4. The three-wire thermal resistance acquisition circuit according to any one of claims 1 to 3, characterized in that: The three-wire thermal resistor acquisition circuit also includes a filter circuit, which is coupled between the operation output terminal and the conversion input terminal.

5. A three-wire thermal resistance measurement circuit, characterized in that: The three-wire thermal resistor measurement circuit includes a three-wire thermal resistor acquisition circuit and a signal processing circuit, and the three-wire thermal resistor acquisition circuit is communication-connected to the signal processing circuit; Wherein, the three-wire thermal resistor acquisition circuit is the three-wire thermal resistor acquisition circuit as claimed in any one of claims 1 to 4.

6. An electronic device, characterized in that: The electronic device comprises a housing and a signal function circuit connected to the housing; Wherein, the signal function circuit is the three-wire thermal resistor acquisition circuit as described in any one of claims 1 to 4, or the three-wire thermal resistor measurement circuit as described in claim 5.

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