CN205843836U - The platinum resistance temperature measuring circuit that a kind of constant-current source drives - Google Patents
The platinum resistance temperature measuring circuit that a kind of constant-current source drives Download PDFInfo
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- CN205843836U CN205843836U CN201620802699.8U CN201620802699U CN205843836U CN 205843836 U CN205843836 U CN 205843836U CN 201620802699 U CN201620802699 U CN 201620802699U CN 205843836 U CN205843836 U CN 205843836U
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Abstract
This utility model belongs to industrial processes detection field, is specifically related to the platinum resistance temperature measuring circuit that a kind of constant-current source drives.Measuring circuit is made up of constant-current source circuit, four-wire system platinum resistance PT1000,1000 Ω precision resistances, signal conditioning circuit, A/D sample circuit, electric power system and the single-chip microcomputer of built-in difference amplifier；The constant current of the 0.4mA that constant-current source circuit provides is added to platinum resistance PT1000 and the two ends of 1000 Ω precision resistances of four-wire system, obtains the voltage signal corresponding with variations in temperature when the temperature varies；Extract platinum sensor and the voltage signal at precision resistance two ends respectively by the difference amplifier that two amplifications are identical, then by the inside difference amplifier of AD7712 the variable quantity of voltage signal be amplified and carry out analog digital conversion.This utility model circuit stability is reliable, can realize high-resolution hydrocode.
Description
Technical field
This utility model relates to industrial processes detection field, particularly relates to the platinum resistance temperature that a kind of constant-current source drives
Degree measuring circuit.
Background technology
In modern society, during temperature survey is widely used in industrial and agricultural production, scientific experiments and daily life.Currently
Although the digital temperature sensor such as widely used AD590, DS18B20 is simple and convenient in thermometry, but it can not meet
The requirement of high precision measuring temperature.The main gage system of platinum resistor temperature measuring sensor has two-wire system, three-wire system and four-wire system three kinds.Two
Although line system distribution is simple, but it has brought the error of lead resistance into.Three-wire system and four-wire system Resistance error of lead are less, especially
It is four-wire system, owing to its circuit loop and voltage measurement circuit are separate so that it is have higher precision.
In platinum resistor temperature measuring, conventional circuit connecting method has bridge method and Method of constant flow source.Owing to bridge method also exists
Non-linear, the method wants to reach the highest precision to be needed to carry out extremely complex process；And constant-current source size is not the most by outward
The impact of boundary's environmental change, its anti-interference degree is higher than bridge method.But when constant-current source electric current is excessive, the devices such as resistance can be caused
Part generates heat, and is produced from heat effect, causes error；When constant-current source electric current is too small, signal to noise ratio is difficult to ensure that again.
In order to solve the problems referred to above, this utility model provides the platinum resistance temperature measuring circuit that a kind of constant-current source drives.
Use 0.4mA constant current, simultaneously drive the temp measuring system of four-wire system platinum resistance and precision resistance, to solve in high precision measuring temperature
Lead resistance and self-heating effect the two difficult point.
Utility model content
This utility model be the technical scheme is that
Measuring circuit by constant-current source circuit, four-wire system platinum resistance PT1000,1000 Ω precision resistances, signal conditioning circuit,
The A/D sample circuit of built-in difference amplifier, electric power system and single-chip microcomputer are constituted.
(1) core devices of constant-current source circuit is REF200 chip
The 4 of REF200 chip, 7,8 feet be connected, 1,2,5 feet are connected, and 6 feet connect+4V voltage.Under this connected mode
The 3 foot output electric currents of REF200 are constant 0.4mA.The electric current of the 3 foot outputs of REF200 is added to the 1000 Ω essences being in series
Cipher telegram resistance and four-wire system platinum resistance PT1000 two ends, obtain two voltage signal U at precision resistance and platinum resistance two ends respectively1With
U2。
(2) signal conditioning circuit is made up of the resistance of 2 OP07 amplifiers and 4 10K
2 OP07 amplifiers are respectively to precision resistance voltage signal U1With platinum resistance voltage signal U2It is amplified, U1Amplify
After signal VINNIt is input to the reverse input end of A/D sampling A/D chip AD7712 passage 1, U2Amplification after signal VINPIt is input to
The positive input of A/D sampling A/D chip AD7712 passage 1.
(3) the A/D sample circuit of built-in difference amplifier is made up of the low-power consumption modulus conversion chip AD7712 of 24
By the inside difference amplifier of the AD7712 variable quantity V to voltage signalINP-VINNIt is amplified and carries out modulus
Conversion, and the digital signal after conversion is input to single-chip microcomputer by serial ports.
(4) electric power system is made up of mu balanced circuit, provides+4VDC to provide regulated power supply for constant-current source circuit, adjusts for signal
Reason circuit, A/D sample circuit and single-chip microcomputer provide+5VDC and-5VDC regulated power supply.
(5) Single-chip Controlling A/D is sampled and accepts the digital signal after A/D changes by serial ports.
Work process is: the constant current of the 0.4mA that REF200 provides is added to platinum resistance PT1000 and 1000 of four-wire system
The two ends of Ω precision resistance.When the temperature varies, the resistance of PT1000 changes, and the resistance of precision resistance keeps not
Become, owing to adding invariable electric current at its two ends, it is possible to obtain the voltage signal corresponding with variations in temperature.Then lead to
Cross two identical difference amplifiers of amplification and extract platinum sensor and the voltage signal at precision resistance two ends respectively, will
It inputs two inputs of the built-in difference amplifier of AD7712 respectively, and the input signal of such difference amplifier is and temperature
Change the variable quantity of corresponding voltage signal.By the inside difference amplifier of AD7712, the variable quantity of voltage signal is carried out
Amplify and carry out analog digital conversion, and the digital signal after conversion is input to single-chip microcomputer by serial ports.Last use in single-chip microcomputer
The non-linear of platinum resistance is compensated by method of least square, in temperature-measuring range, it is carried out algorithm matching.
Advantageous Effects of the present utility model is: circuit stability is reliable, and its random error and systematic error are respectively less than 0.1
DEG C, high-resolution hydrocode can be realized.
Accompanying drawing explanation
Fig. 1 is temperature measuring circuit schematic diagram.
Fig. 2 is constant-current source circuit schematic diagram.
Fig. 3 is signal conditioning circuit schematic diagram.
Detailed description of the invention
Below in conjunction with the accompanying drawings the detailed description of the invention of this utility model device is described further.
Constant-current source part is positioned at the prime of circuit, and its stability and precision have influence on the precision of whole system.REF200
Inside is made up of current source and a mirror current source of two 100 μ A, and this three part is separate, has the strongest resisting and does
Disturb ability.This chip temperature coefficient, less than ± 25ppm/ DEG C, has the lowest temperature drift, and the value of its output electric current is become by ambient temperature
The impact changed is the least.As in figure 2 it is shown, the 4 of REF200 chip, 7,8 feet be connected, 1,2,5 feet are connected, and 6 feet connect+4V voltage.
According to REF200 institute making alive with the characteristic of its output electric current, it is known that when this chip institute making alive is in the range of 2.5V～0V,
The precision and stability of its output electric current is the highest.The output electric current of the REF200 of this circuit connecting mode is constant 0.4mA,
Electric current is flowed out by pin 3.The electric current of 3 feet outputs is added to the precision resistance of 1000 Ω and the temperature sensor PT100 0 being in series
Two ends, can obtain two voltage signal U1 and U2 at precision resistance and sensor two ends respectively, due to the accurate electricity of 1000 Ω
Represented by resistance is resistance when 0 DEG C, so the difference of the two voltage signal precisely PT1000 sensor is compared produced with 0 DEG C
Raw voltage variety.Digital signal after A/D conversion is input to single-chip microcomputer by serial ports, finally with a young waiter in a wineshop or an inn in single-chip microcomputer
The non-linear of platinum resistance is compensated by multiplication, in temperature-measuring range, it is carried out algorithm matching.
Above-described is only preferred implementation of the present utility model, and this utility model is not limited to above example.Can
To understand, those skilled in the art directly derive or associate on the premise of without departing from spirit of the present utility model and design
Oher improvements and changes, within being all considered as being included in protection domain of the present utility model.
Claims (1)
1. the platinum resistance temperature measuring circuit that a constant-current source drives, it is characterised in that measuring circuit is by constant-current source circuit, four lines
Platinum resistance PT1000 processed, 1000 Ω precision resistances, signal conditioning circuit, the A/D sample circuit of built-in difference amplifier, power supply system
System and single-chip microcomputer are constituted；The core devices of constant-current source circuit is REF200 chip, the 4 of REF200 chip, 7,8 feet be connected, 1,
2,5 feet are connected, and 6 feet connect+4V voltage；Under this connected mode, the 3 foot output electric currents of REF200 are constant 0.4mA；Will
The electric current of the 3 foot outputs of REF200 is added to 1000 Ω precision resistances and the four-wire system platinum resistance PT1000 two ends being in series, respectively
Two voltage signal U are obtained at precision resistance and platinum resistance two ends1And U2；Signal conditioning circuit is by 2 OP07 amplifiers and 4
The resistance of 10K Ω is constituted, and 2 OP07 amplifiers are respectively to precision resistance voltage signal U1With platinum resistance voltage signal U2Put
Greatly, U1Signal V after amplificationINNThe reverse input end of input A/D sampling A/D chip AD7712 passage 1, U2Amplification after signal VINP
The positive input of input A/D sampling A/D chip AD7712 passage 1；Low by 24 of the A/D sample circuit of built-in difference amplifier
Power consumption modulus conversion chip AD7712 is constituted, by the inside difference amplifier of the AD7712 variable quantity V to voltage signalINP-
VINNIt is amplified and carries out analog digital conversion, and the digital signal after conversion is input to single-chip microcomputer by serial ports；Electric power system by
Mu balanced circuit is constituted, and provides+4VDC to provide regulated power supply, for signal conditioning circuit, A/D sample circuit and list for constant-current source circuit
Sheet machine provides+5VDC and-5VDC regulated power supply；Single-chip Controlling A/D is sampled, and accepts the numeral letter after A/D changes by serial ports
Number and be converted to temperature signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620802699.8U CN205843836U (en) | 2016-07-27 | 2016-07-27 | The platinum resistance temperature measuring circuit that a kind of constant-current source drives |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620802699.8U CN205843836U (en) | 2016-07-27 | 2016-07-27 | The platinum resistance temperature measuring circuit that a kind of constant-current source drives |
Publications (1)
| Publication Number | Publication Date |
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| CN205843836U true CN205843836U (en) | 2016-12-28 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201620802699.8U Expired - Fee Related CN205843836U (en) | 2016-07-27 | 2016-07-27 | The platinum resistance temperature measuring circuit that a kind of constant-current source drives |
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| CN (1) | CN205843836U (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107560762A (en) * | 2017-09-06 | 2018-01-09 | 阳光电源股份有限公司 | A kind of PT100 resistance temperature measurements method and system |
| CN111406203A (en) * | 2017-12-15 | 2020-07-10 | 恩德莱斯+豪瑟尔韦泽尔有限商业两合公司 | Monitoring the state of a temperature sensor |
| CN111464143A (en) * | 2020-04-03 | 2020-07-28 | 南京中岭艾恩环保科技有限公司 | Circuit for conditioning electric signals of electrostatic sensor |
| CN112649106A (en) * | 2020-12-24 | 2021-04-13 | 西安翔腾微电子科技有限公司 | Novel single-chip platinum resistor signal conditioning circuit and conditioning method |
-
2016
- 2016-07-27 CN CN201620802699.8U patent/CN205843836U/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107560762A (en) * | 2017-09-06 | 2018-01-09 | 阳光电源股份有限公司 | A kind of PT100 resistance temperature measurements method and system |
| CN111406203A (en) * | 2017-12-15 | 2020-07-10 | 恩德莱斯+豪瑟尔韦泽尔有限商业两合公司 | Monitoring the state of a temperature sensor |
| CN111406203B (en) * | 2017-12-15 | 2022-06-21 | 恩德莱斯+豪瑟尔韦泽尔有限商业两合公司 | Monitoring the state of a temperature sensor |
| US11506544B2 (en) | 2017-12-15 | 2022-11-22 | Endress+Hauser Wetzer Gmbh+Co. Kg | Monitoring the state of a temperature sensor |
| CN111464143A (en) * | 2020-04-03 | 2020-07-28 | 南京中岭艾恩环保科技有限公司 | Circuit for conditioning electric signals of electrostatic sensor |
| CN112649106A (en) * | 2020-12-24 | 2021-04-13 | 西安翔腾微电子科技有限公司 | Novel single-chip platinum resistor signal conditioning circuit and conditioning method |
| CN112649106B (en) * | 2020-12-24 | 2023-08-04 | 西安翔腾微电子科技有限公司 | Single-chip platinum resistor signal conditioning circuit and conditioning method |
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| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20161228 Termination date: 20170727 |
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| CF01 | Termination of patent right due to non-payment of annual fee |