CN221350320U - Temperature acquisition circuit and transmitter - Google Patents
Temperature acquisition circuit and transmitter Download PDFInfo
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- CN221350320U CN221350320U CN202323389084.6U CN202323389084U CN221350320U CN 221350320 U CN221350320 U CN 221350320U CN 202323389084 U CN202323389084 U CN 202323389084U CN 221350320 U CN221350320 U CN 221350320U
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- 239000003990 capacitor Substances 0.000 claims abstract description 45
- 230000001105 regulatory effect Effects 0.000 claims description 7
- 238000009434 installation Methods 0.000 claims description 3
- 238000000034 method Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
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Abstract
The utility model provides a temperature acquisition circuit and a transmitter, wherein the temperature acquisition circuit comprises a processor, a thermal resistor and an adjusting resistor, the processor is provided with a constant current source, the H end of the thermal resistor is grounded after passing through a seventh resistor and a second capacitor, the L end of the thermal resistor is grounded after passing through an eighth resistor and a third capacitor, and the G end of the thermal resistor is grounded after passing through a sixth resistor and a fourteenth capacitor; a ninth point capacitor is connected between the common end of the second capacitor and the seventh resistor and the common end of the eighth resistor and the third capacitor; the adjusting resistor is connected with the G end of the thermal resistor, and the other end of the adjusting resistor is grounded. And the constant current source is connected into the processor, the constant current flows through the thermal resistor and the adjusting resistor, and the voltage generated by the adjusting resistor is used as the reference voltage of the ADC in the processor. Whether the thermal resistor is PT100 or PT1000 or other common thermal resistors, the reference voltage is only related to the adjusting resistor, and different resistors are not required to be matched according to different acquisition elements.
Description
Technical Field
The utility model relates to the field of temperature acquisition, in particular to a temperature acquisition circuit and a transmitter.
Background
The existing temperature acquisition commonly uses a voltage division method to realize the resistance value of the thermal resistor, PT100 and PT1000 do not coexist, and the voltage division resistor needs to be replaced, for example, CN 115356543A-thermal resistor measuring circuits, methods, data processing equipment and remote IO devices, the voltage division method of the resistor is adopted, and PT100 and PT1000 need to be divided by different resistors; for another example, CN216770824U, a measurement and fault diagnosis circuit for a thermal resistance temperature sensing element, the same PT100 and PT1000 need different resistors to be paired.
Disclosure of utility model
In order to solve the problems, the utility model aims to provide a temperature acquisition circuit and a transmitter, which solve the problem that different thermal resistors need to be matched with different resistors to realize temperature acquisition.
The utility model is realized by the following technical scheme:
A temperature acquisition circuit comprising: a processor having a constant current source; the H end of the thermal resistor is grounded through a seventh resistor and a second capacitor, the L end of the thermal resistor is grounded through an eighth resistor and a third capacitor, and the G end of the thermal resistor is grounded through a sixth resistor and a fourteenth capacitor; a ninth point capacitor is connected between the common ends of the second capacitor and the seventh resistor and the common ends of the eighth resistor and the third capacitor; the adjusting resistor is connected with the G end of the thermal resistor, and the other end of the adjusting resistor is grounded; and both ends of the ninth capacitor and the common end of the sixth resistor and the fourteenth capacitor are connected with the processor.
Further, the resistance value of the thermal resistor= (ad value R4)/8388607; wherein R4 is the resistance of the adjusting resistor, and AD value=ad 1-2×ad2, AD1 is equal to the AD value of the differential input at two ends of the ninth capacitor, and AD1 is equal to the AD value of the differential input at the common end of the sixth resistor and the fourteenth capacitor and the common end of the eighth resistor and the third capacitor.
Further, the resistance values of the seventh resistor, the eighth resistor and the sixth resistor are the same.
Further, the temperature drift coefficient of the regulating resistor is 10PPM.
Further, the resistance value of the adjusting resistor is 4K-5K.
Further, the processor employs SD93F302-EPT.
Further, a thermocouple installation position is also arranged, the thermocouples are connected in parallel at one ends of the seventh resistor and the eighth resistor far away from the ninth capacitor, and the common end of the thermocouples and the eighth resistor is connected with the 4 pins of the processor through the ninth resistor; wherein, one of the thermocouple and the thermal resistor is connected into a circuit.
A transmitter comprises the temperature acquisition circuit.
Compared with the prior art, the technical scheme of the utility model has the following beneficial effects:
(1) The acquisition circuit is connected to a constant current source generated in the processor, the constant current flows through a thermal resistor and an adjusting resistor, and the voltage generated by the adjusting resistor is used as the reference voltage of an ADC in the processor. Whether the thermal resistor is PT100 or PT1000 or other common thermal resistors, the reference voltage is only related to the adjusting resistor due to the adoption of the constant current source, and different resistors are not required to be matched according to the different collecting elements.
(2) The acquisition circuit is suitable for being used as a temperature acquisition element by using a thermal resistor or a thermocouple, and has wide application range.
(3) When the thermal resistor is used as the acquisition element, the acquisition circuit only needs to ensure that the adjusting resistor has better low-temperature drift performance, and when the thermocouple is used as the acquisition element, only needs to meet the acquisition precision of the ADC carried by the processor, so that the acquisition circuit is less affected by temperature, has high precision and fully utilizes the resources in the processor.
Drawings
FIG. 1 is a schematic diagram of an acquisition circuit provided by an embodiment of the present utility model;
fig. 2 is a schematic diagram of a processor according to an embodiment of the present utility model.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments of the present utility model. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
Referring to fig. 1 and 2, a temperature acquisition circuit includes a processor U1 having a constant current source and an ADC, a thermal resistor TR and a regulating resistor R4, wherein an H end of the thermal resistor TR is grounded through a seventh resistor R7 and a second capacitor C2, and an L end of the thermal resistor TR is grounded through an eighth resistor R8 and a third capacitor C3. The G end of the thermal resistor TR is grounded through the sixth resistor R6 and the fourteenth capacitor C14. A ninth point capacitor C9 is connected between the common terminal of the second capacitor C2 and the seventh resistor R7 and the common terminal of the eighth resistor R8 and the third capacitor C3. The adjusting resistor R4 is connected with the G end of the thermal resistor, and the other end of the adjusting resistor R4 is grounded. The resistor R7 and the capacitor C2, the resistor R8 and the capacitor C3, and the resistor R6 and the capacitor C14 all form an RC filter circuit.
When the three-wire heating resistor TR is connected, the operational amplifier in the processor is utilized to generate constant current, the constant current is output through the ACM pin, the constant current flows through the heating resistor TR and the regulating resistor R4, and the voltage generated by the regulating resistor R4 is used as the reference voltage of the ADC in the processor. Whether the thermal resistor TR is PT100 or PT1000 or other common thermal resistors, because a constant current source is adopted, the reference voltage is only related to the regulating resistor R4, and different resistors are not required to be matched according to different acquisition elements.
Specifically, the resistance value of the thermal resistor= (ad value R4)/8388607; wherein R4 is the resistance of the adjusting resistor, and AD value=ad1-2×ad2, AD1 is equal to the AD value of the differential input between the two ends (AI 4, AI 5) of the ninth capacitor C9, and AD2 is equal to the AD value of the differential input between the common end (AI 5) of the sixth resistor R6 and the fourteenth capacitor C14 and the common end (vref+) of the eighth resistor R8 and the third capacitor C3. The resistance of the thermal resistor TR is only related to the resistance of the adjusting resistor except for the influence of temperature change, when the adjusting resistor R4 adopts a resistor with a low-temperature drift coefficient, the influence of the temperature change on the resistance of the adjusting resistor R4 is ignored, and the resistance of the thermal resistor TR is enabled to follow the temperature change, so that the acquisition precision is improved. Only the resistor R4 is required to be adjusted to be a resistor with a low-temperature drift coefficient, so that the acquisition circuit meets the precision requirement, and the cost is reduced.
Both ends of the ninth capacitor C9 and the common ends of the sixth resistor R6 and the fourteenth capacitor C14 are connected with the processor U1 and connected to an analog input pin of the processor, so that AD values of the endpoints are acquired through an ADC (analog to digital) carried by the processor U1.
In this embodiment, the resistance values of the seventh resistor, the eighth resistor and the sixth resistor are the same, so that the circuit is simplified, the temperature drift coefficient of the resistor is adjusted to 10PPM, the acquisition precision is improved, the resistance value of the resistor R4 is adjusted to 4K-5K, for example, RT0603CRB074K7 can be adopted.
The embodiment is further provided with a thermocouple installation position, a thermocouple TC is connected in parallel to one end, far away from a ninth capacitor C9, of a seventh resistor R7 and an eighth resistor R8, the common end of the thermocouple TC and the eighth resistor R8 is connected with a 4 pin of a processor U1 through the ninth resistor R9, and the processor U1 adopts SD93F302-EPT. When the circuit adopts the thermocouple as the temperature acquisition device, the ACM pin of the processor U1 outputs fixed voltage, mv signals of the thermocouple are directly acquired, ADC reference voltage in the processor U1 is switched to AVDDR, and the temperature drift coefficient of the voltage is 20PPM. When the thermocouple is used as a temperature acquisition component, the acquisition precision is only related to the precision of the ADC inside the processor U1.
It should be noted that in the present collecting circuit, only one of the thermal resistor TR and the thermocouple TC can be connected, and both can not be connected to the circuit at the same time to collect the temperature.
The embodiment provides a transmitter, which comprises the temperature acquisition circuit.
The temperature acquisition circuit is suitable for a thermal resistor or a thermocouple as a temperature acquisition element, and has wide application range; meanwhile, the adjusting resistor does not need to be replaced due to different acquisition elements, so that the circuit is simpler and convenient to use; when the thermal resistor is used as a collecting element, the adjusting resistor is only required to be guaranteed to have good low-temperature drift performance, and when the thermocouple is used as the collecting element, the collecting precision of the ADC carried by the processor is only required to meet the requirement, so that the collecting circuit is less affected by temperature, high in precision and fully utilizes resources in the processor.
While the foregoing description illustrates and describes the preferred embodiments of the present utility model, it is to be understood that the utility model is not limited to the forms disclosed herein, but is not to be construed as limited to other embodiments, but is capable of use in various other combinations, modifications and environments and is capable of changes or modifications within the scope of the inventive concept, either as described above or as a matter of skill or knowledge in the relevant art. And that modifications and variations which do not depart from the spirit and scope of the utility model are intended to be within the scope of the appended claims.
Claims (8)
1. A temperature acquisition circuit, comprising:
a processor having a constant current source;
The H end of the thermal resistor is grounded through a seventh resistor and a second capacitor, the L end of the thermal resistor is grounded through an eighth resistor and a third capacitor, and the G end of the thermal resistor is grounded through a sixth resistor and a fourteenth capacitor; a ninth capacitor is connected between the common ends of the second capacitor and the seventh resistor and the common ends of the eighth resistor and the third capacitor;
The adjusting resistor is connected with the G end of the thermal resistor, and the other end of the adjusting resistor is grounded;
both ends of the ninth capacitor, and the common end of the sixth resistor and the fourteenth capacitor are connected with the analog input pin of the processor.
2. A temperature acquisition circuit according to claim 1, wherein the resistance of the thermal resistor = (ad value R4)/8388607; wherein R4 is the resistance of the adjusting resistor, and AD value=ad 1-2×ad2, AD1 is equal to the AD value of the differential input at two ends of the ninth capacitor, and AD1 is equal to the AD value of the differential input at the common end of the sixth resistor and the fourteenth capacitor and the common end of the eighth resistor and the third capacitor.
3. The temperature acquisition circuit according to claim 1, wherein the seventh resistor, the eighth resistor and the sixth resistor have the same resistance.
4. A temperature acquisition circuit according to claim 1, wherein the temperature drift coefficient of the regulating resistor is 10PPM.
5. A temperature acquisition circuit according to claim 1, wherein the resistance of the regulating resistor is 4K-5K.
6. A temperature acquisition circuit according to claim 1, wherein the processor employs SD93F302-EPT.
7. The temperature acquisition circuit according to claim 6, further comprising a thermocouple installation site, wherein the thermocouple is connected in parallel to one end of the seventh resistor and the eighth resistor far away from the ninth capacitor, and the common end of the thermocouple and the eighth resistor is connected with the 4 pins of the processor through the ninth resistor;
wherein, one of the thermocouple and the thermal resistor is connected into a circuit.
8. A transmitter comprising the temperature acquisition circuit of any one of claims 1 to 7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202323389084.6U CN221350320U (en) | 2023-12-13 | 2023-12-13 | Temperature acquisition circuit and transmitter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202323389084.6U CN221350320U (en) | 2023-12-13 | 2023-12-13 | Temperature acquisition circuit and transmitter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN221350320U true CN221350320U (en) | 2024-07-16 |
Family
ID=91834183
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202323389084.6U Active CN221350320U (en) | 2023-12-13 | 2023-12-13 | Temperature acquisition circuit and transmitter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN221350320U (en) |
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2023
- 2023-12-13 CN CN202323389084.6U patent/CN221350320U/en active Active
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