Sensor adaptive switching circuit and temperature transmitter

Abstract

The present invention provides a sensor adaptive switching circuit and a temperature transmitter, wherein the sensor adaptive switching circuit comprises a sensor driving module, a sensor state detection module, a first gain amplification module, a second gain amplification module and a temperature difference signal output switching module. In the present invention, the sensor access state is detected in combination with the sensor driving module and the sensor state detection module, and the sensor acquisition signal is amplified with different gains by the first gain amplification module and the second gain amplification module to match the analog-to-digital conversion processing range of the post-processing circuit, and then the sensor acquisition signal is amplified and output by the temperature difference signal output switching module according to the sensor access state. Adaptive switching transmission of two different types of sensors can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of instruments and meters, and in particular to a sensor adaptive switching circuit and a temperature transmitter. Background Art

[0002] In the manufacturing industry, the ambient temperature needs to be accurately monitored and controlled during the product manufacturing process, so platinum resistance PT100 or PT1000 is often used to monitor the ambient temperature. However, conventional temperature transmitters have fixed sensor models (i.e., only a single sensor, one of PT100 and PT1000), and different signal acquisition and processing circuits are designed for different PT100 and PT1000 sensor models. It is not easy to simply interchange PT100 and PT1000, which is not very flexible and convenient in both transmitter production and user use.

[0003] Therefore, there is an urgent need for a transmitter technology solution that can adapt to both PT100 and PT1000 sensors. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a sensor adaptive switching technical solution to simultaneously adapt to the collection and transmission of two types of sensors, PT100 and PT1000.

[0005] To achieve the above-mentioned purpose and other related purposes, the technical solution provided by the present invention is as follows.

[0006] A sensor adaptive switching circuit, comprising:

[0007] A sensor driving module, connected to the sensor, providing a driving signal, a first gain reference signal and a second gain reference signal to the sensor;

[0008] A sensor state detection module, whose input end is connected to the sensor driving module, detects the driving signal, obtains and outputs an access state signal;

[0009] A first gain amplification module, whose input end is connected to the sensor driving module, performs differential amplification on the driving signal and the first gain reference signal to obtain and output a first temperature difference signal;

[0010] A second gain amplification module, whose input end is connected to the sensor driving module, performs differential amplification on the driving signal and the second gain reference signal to obtain and output a second temperature difference signal;

[0011] a temperature difference signal output switching module, whose input ends are respectively connected to the sensor state detection module, the first gain amplification module and the second gain amplification module, and under the control of the access state signal, selects and outputs one of the first temperature difference signal and the second temperature difference signal;

[0012] Wherein, the sensor includes a first thermal resistor and a second thermal resistor, the access status signal reflects the access status of the sensor, the access status of the sensor includes the first thermal resistor being connected and the second thermal resistor being connected, when the access status of the sensor is that the first thermal resistor is connected, the temperature difference signal output switching module selects the temperature difference signal corresponding to the first thermal resistor to output to the post-processing circuit; when the access status of the sensor is that the second thermal resistor is connected, the temperature difference signal output switching module selects the temperature difference signal corresponding to the second thermal resistor to output to the post-processing circuit.

[0013] Optionally, the sensor driving module includes a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor; the first power supply voltage is connected to ground after passing through the first resistor and the sensor connected in series in sequence, and the common end of the first resistor and the sensor outputs the driving signal; the first power supply voltage is also connected to ground after passing through the second resistor and the third resistor connected in series in sequence, and the common end of the second resistor and the third resistor outputs the first gain reference signal; the first power supply voltage is also connected to ground after passing through the fourth resistor and the fifth resistor connected in series in sequence, and the common end of the fourth resistor and the fifth resistor outputs the second gain reference signal.

[0014] Optionally, the sensor state detection module includes an operational amplifier, a sixth resistor, a seventh resistor and an eighth resistor, the first power supply voltage is connected in series with the sixth resistor and the seventh resistor and then connected to ground, the inverting input terminal of the operational amplifier is connected to the common end of the sixth resistor and the seventh resistor, the non-inverting input terminal of the operational amplifier is connected to the drive signal, the non-inverting input terminal of the operational amplifier is also connected to the output terminal of the operational amplifier through the eighth resistor connected in series, and the output terminal of the operational amplifier outputs the access status signal.

[0015] Optionally, the first gain amplification module includes a first instrument operational amplifier, a ninth resistor and a first capacitor, the non-inverting input terminal of the first instrument operational amplifier is connected to the drive signal, the inverting input terminal of the first instrument operational amplifier is connected to the first gain reference signal, the ninth resistor is connected in series between the first gain resistor terminal of the first instrument operational amplifier and the second gain resistor terminal of the first instrument operational amplifier, the positive power supply terminal of the first instrument operational amplifier is connected to the second power supply voltage, the negative power supply terminal of the first instrument operational amplifier is connected to the third power supply voltage, the feedback terminal of the first instrument operational amplifier is grounded, the output terminal of the first instrument operational amplifier outputs the first temperature difference signal, and one end of the first capacitor is grounded and the other end is connected to the output terminal of the first instrument operational amplifier.

[0016] Optionally, the second gain amplification module includes a second instrumentation operational amplifier, a tenth resistor and a second capacitor, the non-inverting input terminal of the second instrumentation operational amplifier is connected to the drive signal, the inverting input terminal of the second instrumentation operational amplifier is connected to the second gain reference signal, the tenth resistor is connected in series between the first gain resistor terminal of the second instrumentation operational amplifier and the second gain resistor terminal of the second instrumentation operational amplifier, the positive power supply terminal of the second instrumentation operational amplifier is connected to the second power supply voltage, the negative power supply terminal of the second instrumentation operational amplifier is connected to the third power supply voltage, the feedback terminal of the second instrumentation operational amplifier is grounded, the output terminal of the second instrumentation operational amplifier outputs the second temperature difference signal, and one end of the second capacitor is grounded and the other end is connected to the output terminal of the second instrumentation operational amplifier.

[0017] Optionally, the temperature difference signal output switching module includes a double-pole double-throw analog switch, an eleventh resistor and a twelfth resistor, the positive power supply terminal of the double-pole double-throw analog switch is connected to the second power supply voltage, the negative power supply terminal of the double-pole double-throw analog switch is grounded, the ground terminal of the double-pole double-throw analog switch is grounded, the control terminal of the double-pole double-throw analog switch is connected to the access status signal, the first input terminal of the double-pole double-throw analog switch is connected to the first temperature difference signal, the first output terminal of the double-pole double-throw analog switch is output to the outside after being connected in series with the eleventh resistor, the second input terminal of the double-pole double-throw analog switch is connected to the second temperature difference signal, and the second output terminal of the double-pole double-throw analog switch is output to the outside after being connected in series with the twelfth resistor.

[0018] Optionally, the resistance values ​​of the first resistor, the second resistor, the fourth resistor, the sixth resistor and the seventh resistor are equal, and the resistance value of one of the first thermal resistor and the second thermal resistor is greater than the resistance value of the first resistor, and the resistance value of the other is less than the resistance value of the first resistor, the resistance value of the third resistor is equal to the lower limit of the resistance value of the first thermal resistor, and the resistance value of the fifth resistor is equal to the lower limit of the resistance value of the second thermal resistor.

[0019] Optionally, the first thermal resistor includes one of PT100 and PT1000, and the second thermal resistor includes the other of PT100 and PT1000.

[0020] Optionally, the sensor adaptive switching circuit further includes an analog-to-digital converter signal acquisition port, and the analog-to-digital converter signal acquisition port is connected to the output end of the temperature difference signal output switching module.

[0021] A temperature transmitter comprises the sensor adaptive switching circuit and the post-processing circuit described in any one of the above items. When detecting temperature, the sensor can freely select one of the first thermal resistor and the second thermal resistor to be connected. When the first thermal resistor is connected, the temperature difference signal output switching module selects the temperature difference signal corresponding to the first thermal resistor to output to the post-processing circuit; when the second thermal resistor is connected, the temperature difference signal output switching module selects the temperature difference signal corresponding to the second thermal resistor to output to the post-processing circuit.

[0022] As described above, the sensor adaptive switching circuit and temperature transmitter of the present invention have at least the following beneficial effects:

[0023] The access status of the sensor is detected in combination with the sensor driving module and the sensor status detection module. The sensor's acquisition signal is amplified with different gains through the first gain amplification module and the second gain amplification module to match the analog-to-digital conversion processing range of the post-processing circuit. Then, through the temperature difference signal output switching module, one of the first gain amplification module and the second gain amplification module that matches the sensor is selected according to the access status of the sensor to amplify and output the sensor's acquisition signal, thereby realizing adaptive switching and transmission of two different types of sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Shown is a structural block diagram of the sensor adaptive switching circuit in the present invention.

[0025] Figure 2 Shown is a circuit diagram of the sensor adaptive switching circuit in the present invention. DETAILED DESCRIPTION

[0026] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0027] It should be noted that the diagrams provided in the present embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, so the diagrams only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in actual implementation can be changed at will, and the component layout type may also be more complicated. The structure, proportion, size, etc. shown in the drawings attached to this specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions that the present invention can be implemented, so they have no technical substantive significance. Any modification of the structure, change of the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effect and purpose that can be achieved by the present invention.

[0028] First, if Figure 1 As shown, the present invention provides a sensor adaptive switching circuit, which includes:

[0029] The sensor driving module is connected to the sensor and provides the sensor with a driving signal V0, a ​​first gain reference signal V1 and a second gain reference signal V2;

[0030] The sensor state detection module, whose input terminal is connected to the sensor driving module, detects the driving signal V0, obtains and outputs the access state signal V3;

[0031] A first gain amplification module, whose input terminal is connected to the sensor driving module, performs differential amplification on the driving signal V0 and the first gain reference signal V1 to obtain and output a first temperature difference signal V4;

[0032] A second gain amplification module, whose input terminal is connected to the sensor driving module, performs differential amplification on the driving signal V0 and the second gain reference signal V2 to obtain and output a second temperature difference signal V5;

[0033] The temperature difference signal output switching module has its input ends connected to the sensor state detection module, the first gain amplification module and the second gain amplification module respectively, and under the control of the access state signal V3, selects and outputs one of the first temperature difference signal V4 and the second temperature difference signal V5;

[0034] Among them, the sensor includes a first thermal resistor and a second thermal resistor, and the access status signal reflects the access status of the sensor. The access status of the sensor includes the access of the first thermal resistor and the access of the second thermal resistor. When the access status of the sensor is the access of the first thermal resistor, the temperature difference signal output switching module selects the temperature difference signal corresponding to the first thermal resistor (one of the first temperature difference signal V4 and the second temperature difference signal V5) for external output; when the access status of the sensor is the access of the second thermal resistor, the temperature difference signal output switching module selects the temperature difference signal corresponding to the second thermal resistor (one of the first temperature difference signal V4 and the second temperature difference signal V5) for external output.

[0035] In detail, Figure 2 As shown, the sensor driving module includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a fifth resistor R5; the first power supply voltage VCC1 is connected to the ground GND after passing through the first resistor R1 and the sensor PTR connected in series in sequence, and the common end of the first resistor R1 and the sensor PTR outputs a driving signal V0; the first power supply voltage VCC1 is also connected to the ground GND after passing through the second resistor R2 and the third resistor R3 connected in series in sequence, and the common end of the second resistor R2 and the third resistor R3 outputs a first gain reference signal V1; the first power supply voltage VCC1 is also connected to the ground GND after passing through the fourth resistor R4 and the fifth resistor R5 connected in series in sequence, and the common end of the fourth resistor R4 and the fifth resistor R5 outputs a second gain reference signal V2.

[0036] In detail, Figure 2 As shown, the sensor state detection module includes an operational amplifier U1, a sixth resistor R6, a seventh resistor R7 and an eighth resistor R8. The first power supply voltage VCC1 is connected to the ground GND after passing through the sixth resistor R6 and the seventh resistor R7 connected in series in sequence. The inverting input terminal of the operational amplifier U1 is connected to the common end of the sixth resistor R6 and the seventh resistor R7. The non-inverting input terminal of the operational amplifier U1 is connected to the driving signal V0. The non-inverting input terminal of the operational amplifier U1 is also connected to the output terminal of the operational amplifier U1 after passing through the eighth resistor R8 connected in series. The output terminal of the operational amplifier U1 outputs the access state signal V3.

[0037] In detail, Figure 2As shown, the first gain amplification module includes a first instrument operational amplifier U2, a ninth resistor R9 and a first capacitor C1, a non-inverting input terminal 21 of the first instrument operational amplifier U2 is connected to a driving signal V0, an inverting input terminal 22 of the first instrument operational amplifier U2 is connected to a first gain reference signal V1, a ninth resistor R9 is connected in series between a first gain resistor terminal 23 of the first instrument operational amplifier U2 and a second gain resistor terminal 24 of the first instrument operational amplifier U2, a positive power supply terminal 25 of the first instrument operational amplifier U2 is connected to a second power supply voltage VCC2, a negative power supply terminal 26 of the first instrument operational amplifier U2 is connected to a third power supply voltage VCC3, a feedback terminal 27 of the first instrument operational amplifier U2 is grounded GND, an output terminal 28 of the first instrument operational amplifier U2 outputs a first temperature difference signal V4, one end of the first capacitor C1 is grounded GND, and the other end is connected to the output terminal 28 of the first instrument operational amplifier U2.

[0038] In detail, Figure 2 As shown, the second gain amplification module includes a second instrumentation operational amplifier U3, a tenth resistor R10 and a second capacitor C2, a non-inverting input terminal 31 of the second instrumentation operational amplifier U3 is connected to a driving signal V0, an inverting input terminal 32 of the second instrumentation operational amplifier U3 is connected to a second gain reference signal V2, a tenth resistor R10 is connected in series between a first gain resistor terminal 33 of the second instrumentation operational amplifier U3 and a second gain resistor terminal 34 of the second instrumentation operational amplifier U3, a positive power supply terminal 35 of the second instrumentation operational amplifier U3 is connected to a second power supply voltage VCC2, a negative power supply terminal 36 of the second instrumentation operational amplifier U3 is connected to a third power supply voltage VCC3, a feedback terminal 37 of the second instrumentation operational amplifier U3 is grounded GND, an output terminal 38 of the second instrumentation operational amplifier U3 outputs a second temperature difference signal V5, one end of the second capacitor C2 is grounded GND, and the other end is connected to the output terminal 38 of the second instrumentation operational amplifier U3.

[0039] In detail, Figure 2 As shown, the temperature difference signal output switching module includes a double-pole double-throw analog switch U4, an eleventh resistor R11 and a twelfth resistor R12, the positive power supply terminal 41 of the double-pole double-throw analog switch U4 is connected to the second power supply voltage VCC2, the negative power supply terminal 42 of the double-pole double-throw analog switch U4 is grounded GND, the ground terminal 43 of the double-pole double-throw analog switch U4 is grounded GND, the control terminal 44 of the double-pole double-throw analog switch U4 is connected to the access state signal V3, the first input terminal 45 of the double-pole double-throw analog switch U4 is connected to the first temperature difference signal V4, the first output terminal 46 of the double-pole double-throw analog switch U4 is output to the outside after being connected in series with the eleventh resistor R11, the second input terminal 47 of the double-pole double-throw analog switch U4 is connected to the second temperature difference signal V5, and the second output terminal 48 of the double-pole double-throw analog switch U4 is output to the outside after being connected in series with the twelfth resistor R12.

[0040] Wherein, the sensor PTR includes a first thermal resistor and a second thermal resistor, the first thermal resistor includes one of PT100 and PT1000, and the second thermal resistor includes the other of PT100 and PT1000, that is, when the first thermal resistor is PT100, the second thermal resistor is PT1000, and when the first thermal resistor is PT1000, the second thermal resistor is PT100; the resistance values ​​of the first resistor R1, the second resistor R2, the fourth resistor R4, the sixth resistor R6 and the seventh resistor R7 are equal, and the resistance value of one of the first thermal resistor and the second thermal resistor (that is, PT1000) is greater than the resistance value of the first resistor R1, the second resistor R2, the fourth resistor R4, the sixth resistor R6 and the seventh resistor R7 are equal, and the resistance value of one of the first thermal resistor and the second thermal resistor (that is, PT1000) is greater than the resistance value of the first resistor R1. The resistance value of resistor R1 and the other resistance value (i.e. PT100) are smaller than the resistance value of the first resistor R1, the resistance value of the third resistor R3 is equal to the lower limit of the resistance value of the first thermal resistor, and the resistance value of the fifth resistor R5 is equal to the lower limit of the resistance value of the second thermal resistor; the sensor PTR includes a first thermal resistor and a second thermal resistor, the first thermal resistor includes one of PT100 and PT1000, and the second thermal resistor includes the other of PT100 and PT1000, that is, when the first thermal resistor is PT100, the second thermal resistor is PT1000, and when the first thermal resistor is PT1000, the second thermal resistor is PT100.

[0041] In more detail, Figure 2 As shown, the working principle of the entire sensor adaptive switching circuit is as follows:

[0042] 1) In the sensor driving module, the sensor PTR is driven by a bridge method. The first resistor R1 and the sensor PTR constitute a first voltage dividing branch, which divides the first power supply voltage VCC1 to obtain a driving signal V0. When the resistance of the connected sensor is greater than the resistance of the first resistor R1, the driving signal V0 is greater than VCC / 2. When the resistance of the connected sensor is less than the resistance of the first resistor R1, the driving signal V0 is less than VCC / 2; the second resistor R2 and the third resistor R3 constitute a second voltage dividing branch, which divides the first power supply voltage VCC1 to obtain a first gain reference signal V1; the fourth resistor R4 and the fifth resistor R5 constitute a third voltage dividing branch, which divides the first power supply voltage VCC1 to obtain a second gain reference signal V2.

[0043] 2) In the sensor state detection module, the voltage divider network formed by the sixth resistor R6 and the seventh resistor R7 divides the first power supply voltage VCC1, the voltage of the inverting input terminal of the operational amplifier U1 is equal to VCC / 2, and the non-inverting input terminal of the operational amplifier U1 drives the signal V0. When the drive signal V0 is greater than VCC / 2, the access state signal V3 output by the operational amplifier U1 is high level, which indicates that the resistance of the connected sensor is greater than the resistance of the first resistor R1, that is, the sensor connected to the circuit is PT1000; when the drive signal V0 is less than VCC / 2, the access state signal V3 output by the operational amplifier U1 is low level, which indicates that the resistance of the connected sensor is less than the resistance of the first resistor R1, that is, the sensor connected to the circuit is PT1000.

[0044] 3) Since the sensor can be connected to two types (PT100 or PT1000), the range of the driving signal V0 obtained by sensors of different types is different. In order to convert the driving signal V0 into a signal that can be effectively recognized by the analog-to-digital converter in the post-processing circuit, it is necessary to design a gain amplifier module for each sensor of different types. The designed first gain amplifier module and the second gain amplifier module have the same structure, and the resistance values ​​of the gain resistors (the ninth resistor R9 and the tenth resistor R10) are different. The gain amplification factor is related to the resistance value of the gain resistor. By adjusting the resistance value of the gain resistor, the driving signal V0 can be converted and matched to the acquisition detection range of the analog-to-digital converter (such as 0-3.3V), and the first temperature difference signal V4 and the second temperature difference signal V5 are obtained;

[0045] 4) In the temperature difference signal output switching module, the first temperature difference signal V4 and the second temperature difference signal V5 are selected and outputted through the double-pole double-throw analog switch U4. When the access status signal V3 is at a high level, the first switch in the double-pole double-throw analog switch U4 is turned off and the second switch is turned on, that is, the first output terminal 46 is closed and the second output terminal 48 is opened, and the second gain amplifier module corresponding to PT1000 is selected for amplification and output; when the access status signal V3 is at a low level, the first switch in the double-pole double-throw analog switch U4 is turned on and the second switch is turned off, that is, the first output terminal 46 is opened and the second output terminal 48 is closed, and the first gain amplifier module corresponding to PT100 is selected for amplification and output.

[0046] It should be noted that the above embodiments only use PT100 and PT1000 as examples, and other types of thermal resistors may also be included, which are not limited here; in the temperature range of -50 to 150°C, the resistance value of PT100 varies in the range of 80.31 to 157.33Ω, and the resistance value of PT1000 varies in the range of 803.063 to 1573.251Ω.

[0047] Correspondingly, in an optional embodiment of the present invention, the resistance values ​​of the first resistor R1, the second resistor R2, the fourth resistor R4, the sixth resistor R6 and the seventh resistor R7 are all 500Ω, the first power supply voltage VCC1 is 3.3V, when the sensor PTR is PT100 (i.e. PT100 is connected to the circuit), the driving signal V0 obtained by the voltage division on the sensor PTR is 0.453~0.780V; when the sensor PTR is PT1000 (i.e. PT1000 is connected to the circuit), the driving signal V0 obtained by the voltage division on the sensor PTR is 2.0626~2.5223V. At this time, the ranges of the driving signals V0 corresponding to PT100 and PT1000 are inconsistent. By detecting the voltage value at this time and comparing it with the voltage division 1.65V of the seventh resistor R7, when PT100 is connected, the operational amplifier U1 outputs a low level, and when PT1000 is connected, the operational amplifier U1 outputs a high level. The detection range of the analog-to-digital converter of the post-processing circuit is 0-3.3V. In order to improve the resolution of the temperature signal of the analog-to-digital converter, when the temperature changes from -50 to 150°C, the output signals of the first gain amplifier module and the second gain amplifier module (i.e., the first temperature difference signal V4 and the second temperature difference signal V5) should be as close as possible to 0-3.3V. The first instrument operational amplifier U2 and the second instrument operational amplifier U3 both use instrument operational amplifier INA128, and their gain is Among them, R g The gain resistors (the ninth resistor R9 and the tenth resistor R10) are calculated according to the acquisition range of the corresponding driving signal V0 and the target range of 0 to 3.3 V. The resistance values ​​of the ninth resistor R9 and the tenth resistor R10 are obtained to be 5.48 KΩ and 8.739 KΩ, respectively.

[0048] Optionally, the sensor adaptive switching circuit also includes an analog-to-digital converter signal acquisition port, which is connected to the output end of the temperature difference signal output switching module, and is connected to the analog-to-digital converter of the post-processing circuit through the analog-to-digital converter signal acquisition port, and one of the first temperature difference signal V4 and the second temperature difference signal V5 is input into the analog-to-digital converter for analog-to-digital conversion. The signal after analog-to-digital conversion is then subsequently amplified or subjected to voltage-current conversion and other processing.

[0049] Secondly, based on the above-mentioned sensor adaptive switching circuit, the present invention also provides a temperature transmitter, which includes the above-mentioned sensor adaptive switching circuit and a post-processing circuit. When detecting the temperature, the sensor can freely select one of the first thermal resistor and the second thermal resistor to be connected. When the first thermal resistor is connected, the temperature difference signal output switching module selects the temperature difference signal corresponding to the first thermal resistor to output to the post-processing circuit; when the second thermal resistor is connected, the temperature difference signal output switching module selects the temperature difference signal corresponding to the second thermal resistor to output to the post-processing circuit. Through the above-mentioned sensor adaptive switching circuit, the signal switching and transmission of two different types of sensors can be freely realized, so that one temperature transmitter can adapt to two different types of (temperature) sensors at the same time.

[0050] In summary, the sensor adaptive switching circuit and temperature transmitter provided by the present invention, in combination with the sensor driving module and the sensor state detection module, detect the access state of the sensor, amplify the sensor's acquisition signal with different gains through the first gain amplification module and the second gain amplification module to match the analog-to-digital conversion processing range of the post-processing circuit, and then through the temperature difference signal output switching module, select one of the first gain amplification module and the second gain amplification module that matches the sensor according to the access state of the sensor to amplify and output the sensor's acquisition signal, thereby realizing adaptive switching and transmission of two different types of sensors.

[0051] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A sensor adaptive switching circuit, characterized in that: include: A sensor driving module, connected to the sensor, providing a driving signal, a first gain reference signal and a second gain reference signal to the sensor; A sensor state detection module, whose input end is connected to the sensor driving module, detects the driving signal, obtains and outputs an access state signal; A first gain amplification module, whose input end is connected to the sensor driving module, performs differential amplification on the driving signal and the first gain reference signal to obtain and output a first temperature difference signal; A second gain amplification module, whose input end is connected to the sensor driving module, performs differential amplification on the driving signal and the second gain reference signal to obtain and output a second temperature difference signal; a temperature difference signal output switching module, whose input ends are respectively connected to the sensor state detection module, the first gain amplification module and the second gain amplification module, and under the control of the access state signal, selects and outputs one of the first temperature difference signal and the second temperature difference signal; Wherein, the sensor includes a first thermal resistor and a second thermal resistor, the access status signal reflects the access status of the sensor, the access status of the sensor includes the first thermal resistor being connected and the second thermal resistor being connected, when the access status of the sensor is that the first thermal resistor is connected, the temperature difference signal output switching module selects the temperature difference signal corresponding to the first thermal resistor to output to the post-processing circuit; when the access status of the sensor is that the second thermal resistor is connected, the temperature difference signal output switching module selects the temperature difference signal corresponding to the second thermal resistor to output to the post-processing circuit.

2. The sensor adaptive switching circuit according to claim 1, characterized in that: The sensor driving module comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor; a first power supply voltage is connected to ground after passing through the first resistor and the sensor connected in series in sequence, and a common end of the first resistor and the sensor outputs the driving signal; The first power supply voltage is also connected in series with the second resistor and the third resistor and then grounded, and the common end of the second resistor and the third resistor outputs the first gain reference signal; the first power supply voltage is also connected in series with the fourth resistor and the fifth resistor and then grounded, and the common end of the fourth resistor and the fifth resistor outputs the second gain reference signal.

3. The sensor adaptive switching circuit according to claim 2, characterized in that: The sensor state detection module includes an operational amplifier, a sixth resistor, a seventh resistor and an eighth resistor. The first power supply voltage is connected to ground after being connected in series with the sixth resistor and the seventh resistor in sequence. The inverting input terminal of the operational amplifier is connected to the common end of the sixth resistor and the seventh resistor. The non-inverting input terminal of the operational amplifier is connected to the drive signal. The non-inverting input terminal of the operational amplifier is also connected to the output terminal of the operational amplifier after being connected in series with the eighth resistor. The output terminal of the operational amplifier outputs the access status signal.

4. The sensor adaptive switching circuit according to claim 3, characterized in that: The first gain amplification module includes a first instrument operational amplifier, a ninth resistor and a first capacitor, the non-inverting input terminal of the first instrument operational amplifier is connected to the driving signal, the inverting input terminal of the first instrument operational amplifier is connected to the first gain reference signal, the ninth resistor is connected in series between the first gain resistor terminal of the first instrument operational amplifier and the second gain resistor terminal of the first instrument operational amplifier, the positive power supply terminal of the first instrument operational amplifier is connected to the second power supply voltage, the negative power supply terminal of the first instrument operational amplifier is connected to the third power supply voltage, the feedback terminal of the first instrument operational amplifier is grounded, the output terminal of the first instrument operational amplifier outputs the first temperature difference signal, and one end of the first capacitor is grounded and the other end is connected to the output terminal of the first instrument operational amplifier.

5. The sensor adaptive switching circuit according to claim 4, characterized in that: The second gain amplification module includes a second instrumentation operational amplifier, a tenth resistor and a second capacitor. The non-inverting input terminal of the second instrumentation operational amplifier is connected to the driving signal, the inverting input terminal of the second instrumentation operational amplifier is connected to the second gain reference signal, the tenth resistor is connected in series between the first gain resistor terminal of the second instrumentation operational amplifier and the second gain resistor terminal of the second instrumentation operational amplifier, the positive power supply terminal of the second instrumentation operational amplifier is connected to the second power supply voltage, the negative power supply terminal of the second instrumentation operational amplifier is connected to the third power supply voltage, the feedback terminal of the second instrumentation operational amplifier is grounded, the output terminal of the second instrumentation operational amplifier outputs the second temperature difference signal, and one end of the second capacitor is grounded and the other end is connected to the output terminal of the second instrumentation operational amplifier.

6. The sensor adaptive switching circuit according to claim 5, characterized in that: The temperature difference signal output switching module includes a double-pole double-throw analog switch, an eleventh resistor and a twelfth resistor, the positive power supply terminal of the double-pole double-throw analog switch is connected to the second power supply voltage, the negative power supply terminal of the double-pole double-throw analog switch is grounded, the ground terminal of the double-pole double-throw analog switch is grounded, the control terminal of the double-pole double-throw analog switch is connected to the access status signal, the first input terminal of the double-pole double-throw analog switch is connected to the first temperature difference signal, the first output terminal of the double-pole double-throw analog switch is output to the outside after being connected in series with the eleventh resistor, the second input terminal of the double-pole double-throw analog switch is connected to the second temperature difference signal, and the second output terminal of the double-pole double-throw analog switch is output to the outside after being connected in series with the twelfth resistor.

7. The sensor adaptive switching circuit according to claim 6, characterized in that: The resistance values ​​of the first resistor, the second resistor, the fourth resistor, the sixth resistor and the seventh resistor are equal, and the resistance value of one of the first thermal resistor and the second thermal resistor is greater than the resistance value of the first resistor, and the resistance value of the other is less than the resistance value of the first resistor, the resistance value of the third resistor is equal to the lower limit of the resistance value of the first thermal resistor, and the resistance value of the fifth resistor is equal to the lower limit of the resistance value of the second thermal resistor.

8. The sensor adaptive switching circuit according to claim 7, characterized in that: The first thermal resistor includes one of PT100 and PT1000, and the second thermal resistor includes the other of PT100 and PT1000.

9. The sensor adaptive switching circuit according to claim 8, characterized in that: The sensor adaptive switching circuit also includes an analog-to-digital converter signal acquisition port, and the analog-to-digital converter signal acquisition port is connected to the output end of the temperature difference signal output switching module.

10. A temperature transmitter, characterized in that: The invention comprises a sensor adaptive switching circuit and a post-processing circuit as described in any one of claims 1 to 9. When detecting temperature, the sensor can freely select one of the first thermal resistor and the second thermal resistor to be connected. When the first thermal resistor is connected, the temperature difference signal output switching module selects the temperature difference signal corresponding to the first thermal resistor to output to the post-processing circuit; when the second thermal resistor is connected, the temperature difference signal output switching module selects the temperature difference signal corresponding to the second thermal resistor to output to the post-processing circuit.

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