PT platinum resistance calibration circuit

Abstract

This application relates to a PT platinum resistance thermometer calibration circuit, suitable for calibrating the resistance of a PT platinum resistance thermometer, comprising: a constant current source module, a first diagnostic resistor, a first acquisition module, and a second acquisition module; the output terminal of the constant current source module is connected to the first terminal of the first diagnostic resistor; the second terminal of the first diagnostic resistor is suitable for connecting to the first terminal of the PT platinum resistance thermometer, and the second terminal of the PT platinum resistance thermometer is grounded; the first acquisition module is connected to both the first and second terminals of the first diagnostic resistor, and is suitable for acquiring the voltage across the first diagnostic resistor to obtain the actual current value output by the constant current source module; the second acquisition module is connected to both the first and second terminals of the PT platinum resistance thermometer, and is suitable for acquiring the voltage across the PT platinum resistance thermometer; and the second acquisition module is suitable for calculating the resistance value of the PT platinum resistance thermometer based on the actual current value output by the constant current source module.

Description

Technical Field

[0001] This application relates to the field of PT platinum resistance temperature measurement technology, and in particular to a PT platinum resistance calibration circuit. Background Technology

[0002] Currently, PT100 and PT1000 are two common platinum resistance temperature sensors. Due to their excellent linearity, high stability, and wide temperature range (-200℃ to +650℃), they have become core components for precision temperature measurement in industry and are widely used in industrial control, automotive electronics, aerospace and other fields. When using PT platinum resistance (such as PT100 / PT1000) for high-precision temperature measurement, the constant current source is a key component that provides stable current. Its accuracy, stability (especially temperature drift), and noise performance directly determine the upper limit of the entire system's measurement. The mainstream existing implementation scheme is a classic constant current source circuit based on a precision operational amplifier, a precision reference voltage source, and a power transistor (BJT or MOSFET). Although this scheme is clear in principle and widely used, its accuracy and long-term stability are limited by the drift of the reference source and the setting resistor, the offset voltage and bias current temperature drift of the operational amplifier, and the drift of the power transistor parameters. This leads to errors in the calculation of the resistance value of the PT platinum resistance. Summary of the Invention

[0003] In view of this, this application proposes a PT platinum resistance calibration circuit, which is suitable for calibrating the resistance of PT platinum resistance, including: a constant current source module, a first diagnostic resistor, a first acquisition module, and a second acquisition module; The output terminal of the constant current source module is connected to the first terminal of the first diagnostic resistor; the second terminal of the first diagnostic resistor is suitable for connection to the first terminal of the PT platinum resistance thermometer, and the second terminal of the PT platinum resistance thermometer is grounded. The first acquisition module is connected to the first and second terminals of the first diagnostic resistor respectively, and is suitable for acquiring the voltage across the first diagnostic resistor to obtain the actual output current value of the constant current source module. The second acquisition module is connected to the first and second terminals of the PT platinum resistance thermometer, respectively, and is suitable for acquiring the voltage across the PT platinum resistance thermometer; and the second acquisition module is suitable for calculating the resistance value of the PT platinum resistance thermometer based on the actual current value output by the constant current source module.

[0004] In one possible implementation, a first multiplexer module and a second multiplexer module are also included; the input terminal of the first multiplexer module is electrically connected to the second terminal of the first diagnostic resistor, and the output terminal of the first multiplexer module is adapted to be connected to the first terminal of the PT platinum resistance thermometer; the second acquisition module is connected to the third and fourth terminals of the PT platinum resistance thermometer through the second multiplexer module.

[0005] In one possible implementation, the first multiplexing module includes: a first analog switch and a second analog switch; the input terminal of the first analog switch is electrically connected to the second terminal of a first diagnostic resistor, and the output terminal of the first analog switch is connected to the first terminal of a PT platinum resistance thermometer; the input terminal of the second analog switch is connected to the second terminal of the PT platinum resistance thermometer, and the output terminal of the second analog switch is grounded.

[0006] In one possible implementation, the second multiplexing module includes: a third analog switch and a fourth analog switch; the acquisition terminal of the third analog switch is connected to the third terminal of the PT platinum resistance thermometer, and the output terminal of the third analog switch is connected to the positive input of the second acquisition module; the acquisition terminal of the fourth analog switch is connected to the fourth terminal of the PT platinum resistance thermometer, and the output terminal of the fourth analog switch is connected to the negative input of the second acquisition module.

[0007] In one possible implementation, a second diagnostic resistor and a third acquisition module are also included; the first end of the second diagnostic resistor is connected to the output end of the second analog switch, and the second end of the second diagnostic resistor is grounded; the third acquisition module is connected to the first end and the second end of the second diagnostic resistor respectively, and is suitable for acquiring the voltage across the second diagnostic resistor.

[0008] In one possible implementation, the constant current source module includes a constant current source chip, a transistor, and a regulating transistor; the VG pin of the constant current source chip is electrically connected to the gate of the regulating transistor, the first source of the regulating transistor is connected to the IS pin of the constant current source chip, the second source of the regulating transistor is grounded, and the drain of the regulating transistor is connected to the first end of the first diagnostic resistor; the collector of the transistor is connected to the IS pin of the constant current source chip, the emitter of the transistor is connected to the gate of the regulating transistor, and the base of the transistor is connected to the first source of the regulating transistor.

[0009] In one possible implementation, a protector is also included; one end of the protector is connected to the drain of the regulating tube, and the other end of the protector is grounded.

[0010] In one possible implementation, a first power supply is also included; one end of the first power supply is connected to the VSP pin of the constant current source chip, and the other end of the first power supply is grounded.

[0011] In one possible implementation, it also includes: an equivalent resistor; one end of the equivalent resistor is connected to the SET pin of the constant current source chip, and the other end of the equivalent resistor is grounded.

[0012] In one possible implementation, a second power supply is also included; one end of the second power supply is connected to the VIN pin of the constant current source chip, and the other end of the second power supply is grounded.

[0013] Beneficial effects of this application This application establishes a first diagnostic resistor and a first acquisition module, which work together to form a current detection mechanism. This mechanism detects the current value output by the constant current source module, accurately calculating the actual current value. The second acquisition module then calculates the resistance value of the PT platinum resistance thermometer based on this actual current value. This effectively avoids calculation errors caused by drift of the reference source and setting resistor, operational amplifier offset voltage, bias current temperature drift, and power transistor parameter drift, ensuring the accuracy of the PT platinum resistance measurement. Furthermore, this application directly measures the actual output current of the constant current source through the current detection mechanism, eliminating dependence on the constant current source module parameters. Even if the output current value of the constant current source module changes, the second acquisition module can still calibrate the calculation of the PT platinum resistance value based on the actual current value detected by the current detection mechanism. This ensures that the resistance value calculated by the second acquisition module is closer to the true value, effectively reducing measurement errors and significantly improving the accuracy and reliability of the measurement.

[0014] Other features and aspects of this application will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0015] The accompanying drawings, which are included in and form part of this specification, illustrate exemplary embodiments, features, and aspects of this application together with the specification and serve to explain the principles of this application.

[0016] Figure 1 A circuit diagram showing the PT platinum resistance calibration circuit according to an embodiment of this application is provided. Figure 2 A circuit diagram of a first analog switch according to an embodiment of this application is shown; Figure 3 A circuit diagram of a second analog switch according to an embodiment of this application is shown; Figure 4 A circuit diagram of a third analog switch according to an embodiment of this application is shown; Figure 5 A circuit diagram of a fourth analog switch according to an embodiment of this application is shown; Figure 6 The circuit diagram of the constant current source module according to an embodiment of this application is shown.

[0017] PT platinum resistance thermometer 100; first analog switch 210; second analog switch 220; third analog switch 230; fourth analog switch 240; first acquisition module 310; second acquisition module 320; third acquisition module 330. Detailed Implementation

[0018] Various exemplary embodiments, features, and aspects of this application will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0019] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model or simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0022] Furthermore, to better illustrate this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented without certain specific details. In some instances, methods, means, components, and circuits well-known to those skilled in the art have not been described in detail in order to highlight the main points of this application.

[0023] This application proposes a PT platinum resistance calibration circuit, suitable for calibrating the resistance of a PT platinum resistance 100, such as... Figures 1 to 6As shown, it includes: a constant current source module, a first diagnostic resistor, a first acquisition module 310, and a second acquisition module 320; the output terminal of the constant current source module is connected to the first terminal of the first diagnostic resistor; the second terminal of the first diagnostic resistor is suitable for connection to the first terminal of the PT platinum resistance thermometer 100, and the second terminal of the PT platinum resistance thermometer 100 is grounded; the first acquisition module 310 is connected to the first and second terminals of the first diagnostic resistor respectively, and is suitable for acquiring the voltage across the first diagnostic resistor to obtain the actual current value output by the constant current source module; the second acquisition module 320 is connected to the first and second terminals of the PT platinum resistance thermometer 100 respectively, and is suitable for acquiring the voltage across the PT platinum resistance thermometer 100; the second acquisition module 320 is suitable for calculating the resistance value of the PT platinum resistance thermometer 100 based on the actual current value output by the constant current source module.

[0024] It should be noted that the constant current source module is suitable for providing a stable 0.5mA current to the overall circuit. The first diagnostic resistor R256 is a precision resistor with a resistance of 100Ω, an accuracy of 0.1%, and a low temperature drift. The first diagnostic resistor R256 obtains the actual output current value of the constant current source module by relating its resistance value to the voltage across it. The first acquisition module 310 is suitable for acquiring the voltage between the first and second terminals of the first diagnostic resistor R256. Based on the acquired voltage value across the first diagnostic resistor R256, the first acquisition module 310 can calculate the current value flowing through the first diagnostic resistor R256 using Ohm's law, thereby obtaining the actual output current value of the constant current source module, which provides a basis for the subsequent accurate measurement of the resistance value of the PT platinum resistance 100. The second acquisition module 320 is suitable for acquiring the voltage across the PT platinum resistance 100 and, based on the actual output current value of the constant current source module calculated by the first acquisition module 310, calculates and obtains the resistance value of the PT platinum resistance 100.

[0025] The constant current source module output current flows sequentially through the first diagnostic resistor R256 and the PT platinum resistance 100. The first acquisition module 310 acquires the voltage value across the first diagnostic resistor R256. Since the resistance value of the first diagnostic resistor R256 is known and stable, the first acquisition module 310 can calculate the actual current value flowing through the first diagnostic resistor R256 (i.e., calculate the actual output current of the constant current source module) according to Ohm's law. The second acquisition module 320 acquires the voltage value across the PT platinum resistance 100. Since the first diagnostic resistor R256 and the PT platinum resistance 100 are connected in series, the current values ​​flowing through them are the same. Based on the actual output current of the constant current source module calculated by the first acquisition module 310 and the detected voltage value, the second acquisition module 320 can calculate the resistance value of the PT platinum resistance 100 using Ohm's law.

[0026] This application establishes a first diagnostic resistor R256 and a first acquisition module 310. These two components work together to form a current detection mechanism. This mechanism detects the current value output by the constant current source module, accurately calculating the actual current value. The second acquisition module 320 then calculates the resistance value of the PT platinum resistance 100 based on this actual current value. This effectively avoids the resistance fluctuations caused by drift in the reference source and setting resistors, operational amplifier offset voltage and bias current temperature drift, and power transistor parameter drift, which can lead to variations in the PT platinum resistance 100 resistance. The calculation error is minimized, ensuring the accuracy of the resistance value measurement of the PT platinum resistance 100. Simultaneously, this application directly measures the actual output current of the constant current source through a current detection mechanism, thus eliminating reliance on the parameters of the constant current source module. Even if the output current value of the constant current source module changes, the second acquisition module 320 can still calibrate the calculation of the PT platinum resistance 100 resistance value based on the actual current value detected by the current detection mechanism. This ensures that the resistance value of the PT platinum resistance 100 calculated by the second acquisition module 320 is closer to the true value, effectively reducing measurement errors and significantly improving the accuracy and reliability of the measurement.

[0027] In one possible implementation, such as Figure 1 As shown, it also includes a first multiplexer module and a second multiplexer module; the input terminal of the first multiplexer module is electrically connected to the second terminal of the first diagnostic resistor R256, and the output terminal of the first multiplexer module is adapted to be connected to the first terminal of the PT platinum resistance 100; the second acquisition module 320 is connected to the third and fourth terminals of the PT platinum resistance 100 through the second multiplexer module respectively.

[0028] It should be noted that both the first and second multiplexing modules are applicable to analog multiplexers. The input terminal of the first multiplexing module is connected to the second terminal of the first diagnostic resistor R256, and the output terminal of the first multiplexing module can be connected to the first terminals of multiple PT platinum resistors 100 respectively. By switching the connection path between the first diagnostic resistor R256 and the PT platinum resistors 100, the first multiplexing module can measure multiple PT platinum resistors 100 in the same circuit, improving the versatility and flexibility of the circuit. Correspondingly, the second acquisition module 320 is connected to both ends of multiple PT platinum resistors 100 through the second multiplexing module. By switching the connection path between the second acquisition module 320 and the PT platinum resistors 100, the second multiplexing module ensures that the PT platinum resistors 100 acquired by the second acquisition module 320 are those PT platinum resistors 100 that are turned on by the first multiplexing module.

[0029] In one possible implementation, a processing unit is also included. The processing unit is connected to the control terminals of the first acquisition module 310, the second acquisition module 320, the first multiplexing module, and the second multiplexing module. The processing unit can control the first multiplexing module to switch different PT platinum resistors 100 connected to the circuit, and control the second multiplexing module to select the corresponding PT platinum resistor 100 according to the PT platinum resistor 100 selected by the first multiplexing module. At the same time, the processing unit receives the voltage value across the first diagnostic resistor R256 acquired by the first acquisition module 310 and calculates the actual current value output by the constant current source module; and receives the voltage value across the PT platinum resistor 100 acquired by the second acquisition module 320, and combines it with the actual current value calculated by the data acquired by the first acquisition module 310 to calculate the resistance value of the selected PT platinum resistor 100 according to Ohm's law.

[0030] In one possible implementation method; such as Figure 1 , Figure 3 , Figure 4 As shown, the first multiplexing module includes: a first analog switch 210 and a second analog switch 220; the input terminal of the first analog switch 210 is electrically connected to the second terminal of the first diagnostic resistor R256, and the output terminal of the first analog switch 210 is connected to the first terminal of the PT platinum resistor 100; the input terminal of the second analog switch 220 is connected to the second terminal of the PT platinum resistor 100, and the output terminal of the second analog switch 220 is grounded.

[0031] It should be noted here that pin 8 of the first analog switch 210 is electrically connected to the second terminal of the first diagnostic resistor R256, thereby receiving the current output from the constant current source module through the first diagnostic resistor R256; the output terminal of the first analog switch 210 is a parallel eight-channel port design (i.e., pins S1 to S8 of the first analog switch 210), and the output terminals of the first analog switch 210 (i.e., pins S1 to S8) are respectively electrically connected to the first terminals (CCS-PT+1 to CCS-PT+8) of multiple PT platinum resistors 100. The first analog switch 210 can select any one of these PT platinum resistors 100 as needed, so that the circuit can adapt to the measurement needs of multiple PT platinum resistors 100; the input terminal of the second analog switch 220 is... The design incorporates eight parallel ports (i.e., pins S1 to S8 of the second analog switch 220), with each pin corresponding to one of the pins S1 to S8 of the first analog switch 210. The second terminals of multiple PT platinum resistors 100 are electrically connected to the input terminals (i.e., pins S1 to S8) of the second analog switch 220. Pin 8 of the second analog switch 220 is grounded. The second analog switch 220 works in conjunction with the first analog switch 210 to ensure that when a PT platinum resistor 100 is selected, the other end of that PT platinum resistor 100 is reliably grounded, thus forming a complete current loop. The first multiplexing module, composed of two analog switches, has a simple and clear structure, making it easy to implement and control.

[0032] In one possible implementation, such as Figure 1 , Figure 5 , Figure 6 As shown, the second multiplexing module includes: a third analog switch 230 and a fourth analog switch 240; the acquisition terminal of the third analog switch 230 is connected to the third terminal of the PT platinum resistance 100, and the output terminal of the third analog switch 230 is connected to the positive input of the second acquisition module 320; the acquisition terminal of the fourth analog switch 240 is connected to the fourth terminal of the PT platinum resistance 100, and the output terminal of the fourth analog switch 240 is connected to the negative input of the second acquisition module 320.

[0033] It should be noted here that the acquisition terminals of the third analog switch 230 and the fourth analog switch 240 are both designed with eight-channel ports connected in parallel. The S1 to S8 pins of the third analog switch 230 correspond one-to-one with the S1 to S8 pins of the fourth analog switch 240, and the S1 to S8 pins of the third analog switch 230 correspond one-to-one with the S1 to S8 pins of the first analog switch 210. The third terminals of the multiple PT platinum resistors 100 are electrically connected to the S1 to S8 pins of the third analog switch 230, and the fourth terminals of the multiple PT platinum resistors 100 are electrically connected to the S1 to S8 pins of the fourth analog switch 240. The 8 pins of the third analog switch 230 are connected to the positive input of the second acquisition module 320, and the 8 pins of the fourth analog switch 240 are connected to the negative input of the second acquisition module 320. The third analog switch 230 and the fourth analog switch 240 are used to introduce the voltage signal across the PT platinum resistor 100 into the second acquisition module 320. When the processing unit selects a certain PT platinum resistor 100 for measurement, the corresponding third analog switch 230 and the fourth analog switch 240 simultaneously select the corresponding PT platinum resistor 100, ensuring that the second acquisition module 320 can acquire the true voltage difference across the PT platinum resistor 100, providing an accurate data basis for the subsequent accurate calculation of the resistance value of the PT platinum resistor 100.

[0034] In one possible implementation, an AVCC_5V power supply and an AVCC_-5V power supply are also included; the output of the AVCC_5V power supply is electrically connected to the VDD pin of the first analog switch 210, the VDD pin of the second analog switch 220, the VDD pin of the third analog switch 230, and the VDD pin of the fourth analog switch 240, respectively; the GND pins of the first analog switch 210, the second analog switch 220, the third analog switch 230, and the fourth analog switch 240 are grounded; and the VSS pins of the first analog switch 210, the second analog switch 220, the third analog switch 230, and the fourth analog switch 240 are electrically connected to the AVCC_-5V power supply.

[0035] Furthermore, the EN pins of the first analog switch 210, the second analog switch 220, the third analog switch 230, and the fourth analog switch 240 are electrically connected to the processing unit, thereby enabling the processing unit to control the switching states of the four analog switches; the A0, A1, and A2 pins of the first analog switch 210, the second analog switch 220, the third analog switch 230, and the fourth analog switch 240 are electrically connected to the processing unit, thereby enabling the processing unit to control the four analog switches to select a certain PT platinum resistance 100.

[0036] In one possible implementation, such as Figure 1 As shown, it also includes a second diagnostic resistor R270 and a third acquisition module 330; the first end of the second diagnostic resistor R270 is connected to the output end of the second analog switch 220, and the second end of the second diagnostic resistor R270 is grounded; the third acquisition module 330 is connected to the first end and the second end of the second diagnostic resistor R270 respectively, and is suitable for acquiring the voltage across the second diagnostic resistor R270.

[0037] It should be noted that the first terminal of the second diagnostic resistor R270 is electrically connected to pin 8 of the second analog switch 220, and the second terminal of the second diagnostic resistor R270 is grounded. The voltage acquisition terminal of the third acquisition module 330 is electrically connected to the first and second terminals of the second diagnostic resistor R270. The second diagnostic resistor R270 is a precision resistor with a resistance of 100Ω, an accuracy of 0.1%, and a low temperature drift. By measuring the voltage across the second diagnostic resistor R270, the actual current value flowing through the PT platinum resistance 100 is obtained. The first diagnostic resistor R256, the PT platinum resistance 100, and the second diagnostic resistor R270 are connected in series, so the current flowing through them is the same. By cross-validating the current value measured using the second diagnostic resistor R270 with the current value calculated using the first diagnostic resistor R256, the accuracy of the concentration measurement of the PT platinum resistance 100 is further ensured.

[0038] In one possible implementation, the first acquisition module 310, the second acquisition module 320, and the third acquisition module 330 are all ADC acquisition devices based on the existing model ADS1148QPWRQ1.

[0039] Furthermore, the processing unit is the Rockchip RK3568 processor, a model already in the art.

[0040] In one possible implementation, such as Figure 2As shown, the constant current source module includes a constant current source chip U38, a transistor C9, and an adjustment transistor Q10; the VG pin of the constant current source chip U38 is electrically connected to the gate of the adjustment transistor Q10 (i.e., pin 1 of the adjustment transistor Q10), the first source of the adjustment transistor Q10 (i.e., pin 3 of the adjustment transistor Q10) is connected to the IS pin of the constant current source chip U38, the second source of the adjustment transistor Q10 (i.e., pin 4 of the adjustment transistor Q10) is grounded, and the drain of the adjustment transistor Q10 (i.e., pin 2 of the adjustment transistor Q10) is connected to the first end of the first diagnostic resistor R256; The collector of transistor C9 (i.e., pin 2 of transistor C9) is connected to the IS pin of constant current source chip U38, the emitter of transistor C9 (i.e., pin 3 of transistor C9) is connected to the gate of regulating transistor Q10 (i.e., pin 1 of regulating transistor Q10), and the base of transistor C9 (i.e., pin 1 of transistor C9) is connected to the first source of regulating transistor Q10 (i.e., pin 3 of regulating transistor Q10).

[0041] Furthermore, it also includes a resistor R258. The first end of the resistor R258 is connected to the IS pin of the constant current source chip U38, the second end of the resistor R258 is connected to the first source of the regulating transistor Q10 (i.e., pin 3 of the regulating transistor Q10), and the collector of the transistor C9 (i.e., pin 2 of the transistor C9) is located between the first end of the resistor R258 and the IS pin of the constant current source chip U38.

[0042] Furthermore, it also includes resistor R268, the first end of which is connected to the drain of the regulating transistor Q10 (i.e., pin 2 of the regulating transistor Q10), and the second end of which is connected to the first end of the first diagnostic resistor R256.

[0043] In one possible implementation, a protector D35 is also included; one end of the protector is connected to the drain of the regulating transistor (i.e., pin 2 of the regulating transistor Q10), and the other end of the protector is grounded. It should be noted that one end of the protector D35 is connected to the second end of resistor R268, and the other end of the protector is grounded. The protector D35 is a TVS diode, suitable for suppressing surge voltage impacts on the constant current source chip U38.

[0044] In one possible implementation, a first power supply is also included; one end of the first power supply is connected to the VSP pin of the constant current source chip U38, and the other end of the first power supply is grounded; it should be noted that the first power supply is an AVCC_12V power supply; the first output terminal of the first power supply is electrically connected to the VSP pin of the constant current source chip U38, and the second output terminal of the first power supply is grounded; and a filter capacitor C345 and a filter capacitor C346 are connected in parallel between the first output terminal and the second output terminal of the first power supply, where C345 is a 10μF / 25V capacitor and C346 is a 100nF / 50V capacitor.

[0045] In one possible implementation, a second power supply is also included; one end of the second power supply is connected to the VIN pin of the constant current source chip, and the other end is grounded. It should be noted that the second voltage is an AVCC_VREF_2.5V power supply. The first output terminal of the AVCC_VREF_2.5V power supply is connected to the VIN pin of the constant current source chip block U38, and the second output terminal of the AVCC_VREF_2.5V power supply is connected to one end of a filter capacitor C351. The other end of the filter capacitor C351 is grounded. The filter capacitor C351 is a 100nF / 50V capacitor.

[0046] In one possible implementation, the system further includes: an equivalent resistor; one end of the equivalent resistor is connected to the SET pin of the constant current source chip U38, and the other end of the equivalent resistor is grounded. It should be noted that the equivalent resistor includes resistors R263, R264, and R266 connected in series, with resistor R264 located between resistors R263 and R266. One end of resistor R263 is connected to the SET pin of the constant current source module U38, and the other end of resistor R263 is connected to resistor R264. One end of resistor R266 is connected to resistor R264, and the other end of resistor R266 is grounded. Resistors R263 and R264 are 2KΩ / 0.1% resistors, and resistor R266 is a 10KΩ / 0.1% resistor.

[0047] In one possible implementation, resistor 261 is also included, one end of which is connected to the REGF pin of the constant current source chip U38, and the other end of which is grounded; R261 is a 2KΩ / 0.1% resistor, suitable for adjusting the reference feedback inside the constant current source chip.

[0048] In one possible implementation, the constant current source chip is an XTR111AIDQ chip, and the regulating transistor Q10 is an NTF2955 regulating transistor; the first analog switch 210, the second analog switch 220, the third analog switch 230, and the fourth analog switch 240 are all MAX354EWESO_W_16 chips.

[0049] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A PT platinum resistance calibration circuit, suitable for calibrating the resistance of PT platinum resistance resistors, characterized in that, include: Constant current source module, first diagnostic resistor, first acquisition module, second acquisition module; The output terminal of the constant current source module is connected to the first terminal of the first diagnostic resistor; the second terminal of the first diagnostic resistor is adapted to be connected to the first terminal of the PT platinum resistance, and the second terminal of the PT platinum resistance is grounded. The first acquisition module is connected to the first terminal and the second terminal of the first diagnostic resistor respectively, and is suitable for acquiring the voltage across the first diagnostic resistor to obtain the actual current value output by the constant current source module. The second acquisition module is connected to the first and second ends of the PT platinum resistor respectively, and is suitable for acquiring the voltage across the PT platinum resistor; and the second acquisition module is suitable for calculating the resistance value of the PT platinum resistor based on the actual current value output by the constant current source module.

2. The PT platinum resistance calibration circuit according to claim 1, characterized in that, It also includes a first multiplexing module and a second multiplexing module; The input terminal of the first multiplexing module is electrically connected to the second terminal of the first diagnostic resistor, and the output terminal of the first multiplexing module is adapted to be connected to the first terminal of the PT platinum resistance thermometer. The second acquisition module is connected to the third and fourth terminals of the PT platinum resistance thermometer via the second multiplexing module.

3. The PT platinum resistance calibration circuit according to claim 2, characterized in that, The first multiplexing module includes: a first analog switch and a second analog switch; The input terminal of the first analog switch is electrically connected to the second terminal of the first diagnostic resistor, and the output terminal of the first analog switch is connected to the first terminal of the PT platinum resistance thermometer. The input terminal of the second analog switch is connected to the second terminal of the PT platinum resistance thermometer, and the output terminal of the second analog switch is grounded.

4. The PT platinum resistance calibration circuit according to claim 3, characterized in that, The second multiplexing module includes: a third analog switch and a fourth analog switch; The acquisition terminal of the third analog switch is connected to the third terminal of the PT platinum resistance thermometer, and the output terminal of the third analog switch is connected to the positive input terminal of the second acquisition module. The acquisition terminal of the fourth analog switch is connected to the fourth terminal of the PT platinum resistance thermometer, and the output terminal of the fourth analog switch is connected to the negative input terminal of the second acquisition module.

5. The PT platinum resistance calibration circuit according to claim 4, characterized in that, It also includes a second diagnostic resistor and a third acquisition module; The first end of the second diagnostic resistor is connected to the output terminal of the second analog switch, and the second end of the second diagnostic resistor is grounded. The third acquisition module is connected to the first and second ends of the second diagnostic resistor respectively, and is suitable for acquiring the voltage across the second diagnostic resistor.

6. The PT platinum resistance calibration circuit according to claim 1, characterized in that, The constant current source module includes a constant current source chip, a transistor, and a regulating transistor; The VG pin of the constant current source chip is electrically connected to the gate of the regulating transistor, the first source of the regulating transistor is connected to the IS pin of the constant current source chip, the second source of the regulating transistor is grounded, and the drain of the regulating transistor is connected to the first end of the first diagnostic resistor. The collector of the transistor is connected to the IS pin of the constant current source chip, the emitter of the transistor is connected to the gate of the regulating transistor, and the base of the transistor is connected to the first source of the regulating transistor.

7. The PT platinum resistance calibration circuit according to claim 6, characterized in that, It also includes protectors; One end of the protector is connected to the drain of the regulating tube, and the other end of the protector is grounded.

8. The PT platinum resistance calibration circuit according to claim 6, characterized in that, It also includes the first power source; One end of the first power supply is connected to the VSP pin of the constant current source chip, and the other end of the first power supply is grounded.

9. The PT platinum resistance calibration circuit according to claim 6, characterized in that, It also includes; equivalent resistance; One end of the equivalent resistor is connected to the SET pin of the constant current source chip, and the other end of the equivalent resistor is grounded.

10. The PT platinum resistance calibration circuit according to claim 6, characterized in that, It also includes a second power source; One end of the second power supply is connected to the VIN pin of the constant current source chip, and the other end of the second power supply is grounded.

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