CN110940435A - 0 ~ 5V output Pt100 temperature signal conditioning circuit - Google Patents
0 ~ 5V output Pt100 temperature signal conditioning circuit Download PDFInfo
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- CN110940435A CN110940435A CN201911201995.7A CN201911201995A CN110940435A CN 110940435 A CN110940435 A CN 110940435A CN 201911201995 A CN201911201995 A CN 201911201995A CN 110940435 A CN110940435 A CN 110940435A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
- G01K7/18—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer
- G01K7/20—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer in a specially-adapted circuit, e.g. bridge circuit
- G01K7/21—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer in a specially-adapted circuit, e.g. bridge circuit for modifying the output characteristic, e.g. linearising
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
- G01K7/18—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer
- G01K7/20—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer in a specially-adapted circuit, e.g. bridge circuit
- G01K7/203—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer in a specially-adapted circuit, e.g. bridge circuit in an oscillator circuit
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
- G01K7/18—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer
- G01K7/20—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer in a specially-adapted circuit, e.g. bridge circuit
- G01K7/206—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer in a specially-adapted circuit, e.g. bridge circuit in a potentiometer circuit
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Abstract
The invention discloses a circuit structure which converts a resistance signal in a temperature range of-60-200 ℃ into 0V-5V DC to be output on the basis of a Pt100 platinum resistance temperature sensor and has a power supply voltage of (28 +/-3) V DC, and belongs to the field of signal conditioning circuits of platinum resistance temperature sensors. Under the condition of single power supply, the full operational amplifier constructs a cross current source circuit, a precise zero setting and voltage stabilizing circuit, improves the load capacity of output signals, realizes the output of 0V-5V DC voltage, and has compact circuit structure.
Description
Technical Field
The invention discloses a circuit structure which converts a resistance signal in a temperature range of-60-200 ℃ into 0V-5V DC to be output on the basis of a Pt100 platinum resistance temperature sensor and has a power supply voltage of (28 +/-3) V DC, and belongs to the field of signal conditioning circuits of platinum resistance temperature sensors.
Background
The temperature sensor is always an important sensor in the airborne sensor parameter measurement category, and no matter a fixed wing or a non-fixed wing, the temperature sensor directly provides an application in the past to provide a temperature resistance signal, the application needs airborne equipment to provide power supply of a cross current source, and the airborne power supply is generally direct-current voltage. Therefore, in recent years, there is an increasing demand for products that supply dc power and output a temperature-voltage signal. In the current market, the temperature transmitter which is applied mostly outputs 4 mA-20 mA DC, the equipment at the temperature acquisition end also needs to convert a direct current signal into response voltage through a precise standard resistor, and an initial voltage to ground caused by the division of 4mA initial current always exists. In the civil market, there are also temperature sensors providing dc power supply and dc output, but the initial output voltage is usually 0.5VDC or 1VDC, and actually, an output resistor is added on the basis of a transducer to perform current-to-voltage conversion, so that the output load capacity is limited, the temperature measurement is affected along with the change of the output load, and the size is large. Aiming at the airborne application characteristics, a voltage output type temperature signal conditioning circuit modified on the basis of a transmitter is eliminated, the airborne power supply and signal conditioning requirements and volume requirements are met, the signal loading capacity is improved, and the temperature signal conditioning circuit structure is designed, so that the airborne temperature signal conditioning circuit has important engineering application significance.
The prior art comprises: operational amplifier, resistance, electric capacity, voltage regulation chip, zener diode.
The effect of the prior art is as follows: the traditional temperature transmitter circuit outputs 4 mA-20 mA DC, which has the greatest advantage of being convenient for transmitting temperature signals in a long distance, but the current signals are generally converted into voltage signals when the temperature signals are processed, so the resistance temperature characteristic of a current-to-voltage conversion resistor, and the resistance precision, the output voltage range and the resistance temperature characteristic of an equivalent current-to-voltage conversion resistor formed by the conversion resistor and a load resistor influence the temperature measurement precision. And the output voltage is reduced to 0V, so that power is supplied by a positive power supply and a negative power supply, and the requirement on the external environment is higher and an electrical interface is increased.
Correlation documents or inventions
A temperature transmitter circuit structure, patent No.: CN207095717U
Patent No. 2: CN105784168A
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention aims at the airborne application characteristics, constructs a cross current source circuit, a precise zero setting and voltage stabilizing circuit by full operational amplifier under the condition of single power supply, improves the load carrying capacity of output signals, realizes the output of 0V-5V DC voltage, and has a compact circuit structure.
The specific technical scheme of the invention is that
Aiming at the defects of the prior art, the invention provides a 0-5V output Pt100 temperature signal conditioning circuit, which comprises a power circuit, a constant current source circuit and a collection zero setting circuit;
the power supply circuit is used for conditioning an input signal voltage Vi into a conditioning power supply output end of 12V through a three-terminal voltage-stabilizing chip U1 in cooperation with voltage stabilization of a voltage-stabilizing tube and filtering of an input and output capacitor so as to meet the condition that the conditioning power supply output end is more than 2 times of 5V of output voltage, and meanwhile, the conditioning output of the three-terminal voltage-stabilizing chip U1 is converted into 2.5V of reference voltage through a U2 precision reference voltage source chip U2 for zero setting;
the constant current source circuit is realized by constructing a positive and negative feedback resistor network through introducing a 2.5V reference voltage and through a 1/4 operational amplifier of an operational amplifier chip U3, and the resistor R8 and the resistor R9 realize coarse and fine adjustment of a constant current value;
the acquisition zero setting circuit is used for realizing a first-stage differential operational amplifier circuit and a second-quarter subtraction circuit through an amplifying circuit and a zero setting circuit which are formed by 2/4 operational amplifiers and 3/4 operational amplifiers in an operational amplifier chip U3; the amplification factor of the first-stage differential operational amplifier circuit is 4.5 times, and the differential input end parallel resistor R10 is used for realizing 12V output and prompting an open-circuit fault when the Pt100 platinum resistor has the open-circuit fault; the second-stage subtraction circuit is used for carrying out subtraction operation on the zeroing voltage formed by the temperature voltage signal in-phase proportional amplification circuit and the reverse-end precision reference voltage, and the amplification proportion is 5.4 times; and the two-stage operational amplifier circuits are provided with filter capacitors in feedback loops.
Preferably, the power supply circuit comprises an input signal voltage Vi, a conditioning power supply output end, a reference voltage output end, a diode D1, a diode D2, a resistor R1, a resistor R2, a resistor R24, a resistor R25, a resistor R26, a three-terminal voltage-stabilizing chip U1, a precision reference voltage source chip U2, a capacitor C1 and a capacitor C2;
one end of the resistor R24 is connected to the input signal voltage Vi; the other end of the R24 is simultaneously connected with the cathode of the diode D1, the cathode of the diode D2, one end of the capacitor C1 and the first pin of the three-terminal voltage stabilizing chip U1; the second pin of the three-terminal voltage-stabilizing chip U1 is simultaneously connected with one end of the resistor R1 and one end of the resistor R2; a third pin of the three-terminal voltage-stabilizing chip U1 is simultaneously connected with the other end of the resistor R2, the output end of the conditioning power supply, one end of the capacitor C2 and one end of the resistor R25; the other end of the resistor R25 is connected with the resistor R26 and a first pin of the precision reference voltage source chip U2; a second pin of the precision reference voltage source chip U2 is connected with a reference voltage output end; the anode of the diode D1, the anode of the diode D2, the other end of the capacitor C1, the other end of the resistor R1, the other end of the capacitor C2, the other end of the resistor R26 and a third pin of the precision reference voltage source chip U2 are grounded;
the output end of the conditioning power supply is +12V, the output end of the reference voltage is +2.5V, the specification of a diode D1 and a diode D2 is 1N5246B, the resistance value of a resistor R1 is 2K omega, the resistance value of a resistor R2 is 240 omega, the resistance value of a resistor R24 is 1K omega, the resistance value of a resistor R25 is 5K omega, the resistance value of a resistor R26 is 24K omega, the specification of a three-end voltage stabilizing chip U1 is LM117H, the specification of a precision reference voltage source chip U2 is AD580UH, the capacitance of a capacitor C1 is 0.1 muF, and the capacitance of a capacitor C2 is 1 muF.
Preferably, the constant current source circuit comprises a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a capacitor C3, a capacitor C4, an operational amplifier chip U3, a positive temperature indicator Ti + and a negative temperature indicator Ti-;
one end of the resistor R3 is connected with the output end of the precision reference voltage source chip U2, and the other end is connected with one end of the resistor R4; the other end of the resistor R4 is simultaneously connected with a third pin of the operational amplifier chip U3 and one end of the resistor R7; the other end of the resistor R7 is simultaneously connected with one end of a resistor R8, one end of a resistor R9, positive temperature indication Ti + and one end of a capacitor C4; the other end of the resistor R8 is simultaneously connected with the other end of the resistor R9, a first pin of the operational amplifier chip U3 and one end of the resistor R6; the other end of the resistor R6 is simultaneously connected with a second pin of the operational amplifier chip U3 and one end of the resistor R5; a fourth pin of the operational amplifier chip U3 is simultaneously connected with the output end of the conditioning power supply and one end of the capacitor C3; the other end of the resistor R5, the eleventh pin of the operational amplifier chip U3 and the other end of the capacitor C3 are grounded; the other end of the capacitor C4 is connected with a negative temperature indicator Ti < - > and is grounded;
the resistance of the resistor R3 is 1.54K omega, the resistance of the resistor R4 is 221K omega, the resistance of the resistor R5 is 221K omega, the resistance of the resistor R6 is 221K omega, the resistance of the resistor R7 is 221K omega, the resistance of the resistor R8 is 1K omega, the resistance of the resistor R9 is 2.2M omega, the capacitance of the capacitor C3 is 0.1 muF, the capacitance of the capacitor C4 is 1 muF, and the specification of the operational amplifier chip U3 is OPA4703 UA.
Preferably, the acquisition zero-setting circuit comprises a resistor R28, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a varistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R27, a capacitor C5, a capacitor C6, an operational amplifier chip U3, a temperature measurement element output port To +, a temperature measurement element output port To-and an output port Vo;
one end of the resistor R28 is connected with the positive temperature indicator Ti +, and the other end is simultaneously connected with one end of the network interface To-, the resistor R10 and one end of the resistor R11; the other end of the resistor R10 is simultaneously connected with the network interface To + and one end of the resistor R12; the other end of the resistor R11 is simultaneously connected with one end of the capacitor C5, one end of the resistor R14 and the sixth pin of the operational amplifier chip U3; the other end of the resistor R12 is simultaneously connected with one end of the resistor R13 and the fifth pin of the operational amplifier chip U3; the other end of the resistor R13 is connected with an eleventh pin of the operational amplifier chip U3; the other end of the capacitor C5 is simultaneously connected with the other end of the resistor R14, a seventh pin of the operational amplifier chip U3 and one end of the resistor R16; the other end of the resistor R16 is simultaneously connected with the tenth pin of the operational amplifier chip U3 and one end of the resistor R27; the other end of the resistor R27 is connected with an eleventh pin of the operational amplifier chip U3; an eighth pin of the operational amplifier chip U3 is simultaneously connected with one end of the resistor R21, one end of the resistor R22 and one end of the capacitor C6; the other end of the resistor R22 is simultaneously connected with one ends of the output ports Vo and R23; the other end of R23 is grounded; the other end of the resistor R21 is connected with the other end of the resistor R20; the other end of the capacitor C6 is simultaneously connected with one end of the resistor R19, one end of the resistor R20 and the ninth pin of the operational amplifier chip U3; the other end of the resistor R19 is simultaneously connected with one end of the resistor R18 and a second pin of the rheostat R15; the other end of the resistor R18 is connected with a reference voltage output end; a first pin of the rheostat R15 is connected with one end of the resistor R17; the other end of the resistor R17 is grounded;
the resistance value of the resistor R28 is 0 Ω, the resistance value of the resistor R10 is 680K Ω, the resistance value of the resistor R11 is 221K Ω, the resistance value of the resistor R12 is 221K Ω, the resistance value of the resistor R13 is 1M Ω, the resistance value of the resistor R14 is 1M Ω, the maximum resistance value of the varistor R15 is 1K Ω, the resistance value of the resistor R16 is 6.81K Ω, the resistance value of the resistor R17 is 16.5K Ω, the resistance value of the resistor R18 is 24K Ω, the resistance value of the resistor R19 is 1M Ω, the resistance value of the resistor R20 is 2.2M Ω, the resistance value of the resistor R21 is 2.2M Ω, the resistance value of the resistor R22 is 240 Ω, the resistance value of the resistor R23 is 1K Ω, the resistance value of the resistor R27 is 1M Ω, the capacitance value of the capacitor C5 is 33nF, and the capacitance value of the capacitor C6 is 0..
The preferred 0-5V output Pt100 temperature signal conditioning circuit further comprises a voltage follower circuit; the voltage follower circuit comprises an operational amplifier chip U3 and an output port Vo 2; a twelfth pin of the operational amplifier chip U3 is connected with the output port Vo; the fourteenth pin of the operational amplifier chip U3 is connected to the output port Vo2 and the thirteenth pin of the operational amplifier chip U3.
The invention can bring the following beneficial effects:
1) the conditioning circuit realizes the power supply of a single power supply and achieves the direct current output of 0V-5 VDC, and the initial voltage to ground introduced by the lower limit current of the output of the transmitter is eliminated.
2) The single operational amplifier realizes the construction of a constant current, proportional amplification and zero setting circuit, is convenient for the integration and volume miniaturization of circuit devices, and avoids noise errors introduced by current amplification devices such as triodes and the like.
3) The platinum resistor input end is disconnected and is connected with the resistor, so that 12V prompt of disconnection output is realized, and error signals are prevented from being introduced by an input suspension.
4) The circuit amplification factor is divided equally by the two-stage operational amplifier, so that the constant current power supply of the platinum resistor can be reduced, and the power consumption and the influence brought by the self-heating effect of the platinum resistor are reduced besides the amplification factor is improved.
5) The platinum resistor input end realizes the industrial field application of two connection methods of a three-wire system and a four-wire system through a short-circuit resistor.
6) The power supply voltage conditioning end further improves the voltage stabilizing effect and the anti-fluctuation capability through serially connecting a resistor and parallelly connecting a voltage stabilizing diode.
7) And low-amplitude precision reference voltage is introduced to realize the precision adjustment of the constant current source output and the zero position of the zero setting subtraction circuit.
8) And filter capacitors are added at the input end of the platinum resistor and a feedback loop of the operational amplifier for filtering and preventing the operational amplifier from self-oscillation.
9) The operational amplifier type is generally a double operational amplifier or a four operational amplifier, and the output signal end can select the voltage follower to output according to the requirement, so that the output driving capability is improved. The amplification ratio and the zero setting value can be adjusted to expand the temperature measuring range of the circuit to a section needing to be measured.
Drawings
FIG. 1 is an overall circuit diagram of the present invention;
FIG. 2 is a circuit diagram of a power circuit;
FIG. 3 is a circuit diagram of a constant current source circuit;
FIG. 4 is a circuit diagram of an acquisition zeroing circuit;
fig. 5 is a circuit diagram of a voltage follower circuit.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings.
In one embodiment of the invention, the 0-5V output Pt100 temperature signal conditioning circuit shown in FIG. 1 comprises a power supply circuit, a constant current source circuit and a collecting and zeroing circuit;
the power supply circuit is used for conditioning an input signal voltage Vi into a 12V conditioning power supply output end through the three-terminal voltage-stabilizing chip U1 in cooperation with voltage stabilization of a voltage-stabilizing tube and filtering of an input and output capacitor so as to meet the condition that the conditioning power supply output end is more than 2 times of 5V of output voltage, and meanwhile, the conditioning output of the three-terminal voltage-stabilizing chip U1 is converted into 2.5V reference voltage through the U2 precision reference voltage source chip U2 for zero setting;
the constant current source circuit is realized by constructing a positive and negative feedback resistor network through introducing a 2.5V reference voltage and through a 1/4 operational amplifier of an operational amplifier chip U3, and realizing coarse and fine adjustment of a constant current value by a resistor R8 and a resistor R9;
the acquisition zero setting circuit is used for realizing a first-stage differential operational amplifier circuit and a second-quarter subtraction circuit through an amplifying circuit and a zero setting circuit which are formed by 2/4 operational amplifiers and 3/4 operational amplifiers in an operational amplifier chip U3; the amplification factor of the first-stage differential operational amplifier circuit is 4.5 times, and the differential input end parallel resistor R10 is used for realizing 12V output and prompting an open-circuit fault when the Pt100 platinum resistor has the open-circuit fault; the second-stage subtraction circuit is used for carrying out subtraction operation on the zeroing voltage formed by the temperature voltage signal in-phase proportional amplification circuit and the reverse-end precision reference voltage, and the amplification proportion is 5.4 times; the two-stage operational amplifier circuit is provided with a filter capacitor in a feedback loop.
In one embodiment, the power supply circuit comprises an input signal voltage Vi, a conditioning power supply output terminal, a reference voltage output terminal, a diode D1, a diode D2, a resistor R1, a resistor R2, a resistor R24, a resistor R25, a resistor R26, a three-terminal voltage-stabilizing chip U1, a precision reference voltage source chip U2, a capacitor C1 and a capacitor C2;
one end of the resistor R24 is connected to the input signal voltage Vi; the other end of the R24 is simultaneously connected with the cathode of the diode D1, the cathode of the diode D2, one end of the capacitor C1 and the first pin of the three-terminal voltage stabilizing chip U1; the second pin of the three-terminal voltage-stabilizing chip U1 is simultaneously connected with one end of the resistor R1 and one end of the resistor R2; a third pin of the three-terminal voltage-stabilizing chip U1 is simultaneously connected with the other end of the resistor R2, the output end of the conditioning power supply, one end of the capacitor C2 and one end of the resistor R25; the other end of the resistor R25 is connected with the resistor R26 and a first pin of the precision reference voltage source chip U2; a second pin of the precision reference voltage source chip U2 is connected with a reference voltage output end; the anode of the diode D1, the anode of the diode D2, the other end of the capacitor C1, the other end of the resistor R1, the other end of the capacitor C2, the other end of the resistor R26 and a third pin of the precision reference voltage source chip U2 are grounded;
the output end of the conditioning power supply is +12V, the output end of the reference voltage is +2.5V, the specification of the diode D1 and the diode D2 is 1N5246B, the resistance value of the resistor R1 is 2K omega, the resistance value of the resistor R2 is 240 omega, the resistance value of the resistor R24 is 1K omega, the resistance value of the resistor R25 is 5K omega, the resistance value of the resistor R26 is 24K omega, the specification of the three-terminal voltage stabilizing chip U1 is LM117H, the specification of the precision reference voltage source chip U2 is AD580UH, the capacitance of the capacitor C1 is 0.1 muF, and the capacitance of the capacitor C2 is 1 muF.
In one embodiment, the constant current source circuit comprises a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a capacitor C3, a capacitor C4, an operational amplifier chip U3, a positive temperature indicator Ti + and a negative temperature indicator Ti-;
one end of the resistor R3 is connected with the output end of the precision reference voltage source chip U2, and the other end is connected with one end of the resistor R4; the other end of the resistor R4 is simultaneously connected with a third pin of the operational amplifier chip U3 and one end of the resistor R7; the other end of the resistor R7 is simultaneously connected with one end of a resistor R8, one end of a resistor R9, positive temperature indication Ti + and one end of a capacitor C4; the other end of the resistor R8 is simultaneously connected with the other end of the resistor R9, a first pin of the operational amplifier chip U3 and one end of the resistor R6; the other end of the resistor R6 is simultaneously connected with a second pin of the operational amplifier chip U3 and one end of the resistor R5; a fourth pin of the operational amplifier chip U3 is simultaneously connected with the output end of the conditioning power supply and one end of the capacitor C3; the other end of the resistor R5, the eleventh pin of the operational amplifier chip U3 and the other end of the capacitor C3 are grounded; the other end of the capacitor C4 is connected with a negative temperature indicator Ti-and is grounded;
the resistance of the resistor R3 is 1.54K omega, the resistance of the resistor R4 is 221K omega, the resistance of the resistor R5 is 221K omega, the resistance of the resistor R6 is 221K omega, the resistance of the resistor R7 is 221K omega, the resistance of the resistor R8 is 1K omega, the resistance of the resistor R9 is 2.2M omega, the capacitance of the capacitor C3 is 0.1 muF, the capacitance of the capacitor C4 is 1 muF, and the specification of the operational amplifier chip U3 is OPA4703 UA.
In one embodiment, the collecting and zero-adjusting circuit comprises a resistor R28, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a rheostat R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R27, a capacitor C5, a capacitor C6, an operational amplifier chip U3, a temperature measuring element output port To +, a temperature measuring element output port To-and an output port Vo;
one end of the resistor R28 is connected with the positive temperature indicator Ti +, and the other end is simultaneously connected with one end of the network interface To-, the resistor R10 and one end of the resistor R11; the other end of the resistor R10 is simultaneously connected with the network interface To + and one end of the resistor R12; the other end of the resistor R11 is simultaneously connected with one end of the capacitor C5, one end of the resistor R14 and the sixth pin of the operational amplifier chip U3; the other end of the resistor R12 is simultaneously connected with one end of the resistor R13 and the fifth pin of the operational amplifier chip U3; the other end of the resistor R13 is connected with an eleventh pin of the operational amplifier chip U3; the other end of the capacitor C5 is simultaneously connected with the other end of the resistor R14, a seventh pin of the operational amplifier chip U3 and one end of the resistor R16; the other end of the resistor R16 is simultaneously connected with the tenth pin of the operational amplifier chip U3 and one end of the resistor R27; the other end of the resistor R27 is connected with an eleventh pin of the operational amplifier chip U3; an eighth pin of the operational amplifier chip U3 is simultaneously connected with one end of the resistor R21, one end of the resistor R22 and one end of the capacitor C6; the other end of the resistor R22 is simultaneously connected with one ends of the output ports Vo and R23; the other end of R23 is grounded; the other end of the resistor R21 is connected with the other end of the resistor R20; the other end of the capacitor C6 is simultaneously connected with one end of the resistor R19, one end of the resistor R20 and the ninth pin of the operational amplifier chip U3; the other end of the resistor R19 is simultaneously connected with one end of the resistor R18 and a second pin of the rheostat R15; the other end of the resistor R18 is connected with a reference voltage output end; a first pin of the rheostat R15 is connected with one end of the resistor R17; the other end of the resistor R17 is grounded;
the resistance value of the resistor R28 is 0 Ω, the resistance value of the resistor R10 is 680K Ω, the resistance value of the resistor R11 is 221K Ω, the resistance value of the resistor R12 is 221K Ω, the resistance value of the resistor R13 is 1M Ω, the resistance value of the resistor R14 is 1M Ω, the maximum resistance value of the varistor R15 is 1K Ω, the resistance value of the resistor R16 is 6.81K Ω, the resistance value of the resistor R17 is 16.5K Ω, the resistance value of the resistor R18 is 24K Ω, the resistance value of the resistor R19 is 1M Ω, the resistance value of the resistor R20 is 2.2M Ω, the resistance value of the resistor R21 is 2.2M Ω, the resistance value of the resistor R22 is 240 Ω, the resistance value of the resistor R23 is 1K Ω, the resistance value of the resistor R27 is 1M Ω, the capacitance value of the capacitor C5 is 33nF, and the capacitance value of the capacitor C6 is 0..
In one embodiment, the 0-5V output Pt100 temperature signal conditioning circuit further comprises a voltage follower circuit; the voltage follower circuit comprises an operational amplifier chip U3 and an output port Vo 2; a twelfth pin of the operational amplifier chip U3 is connected with the output port Vo; the fourteenth pin of the operational amplifier chip U3 is connected to the output port Vo2 and the thirteenth pin of the operational amplifier chip U3.
Overall description:
the three-terminal voltage-stabilizing chip U1, the resistor R1 and the resistor R2 form a 12V voltage-stabilizing output, the capacitor C1 and the capacitor C2 are used for power supply filtering, and the resistor R24, the diode D1 and the diode D2 which are used for voltage stabilization are used for current limiting of power supply input and further improving the voltage-stabilizing performance. The resistor R25, the resistor R26 and the precision reference voltage source chip U2 form 2.5V precision reference voltage output.
The resistors R3 to R9 and the operational amplifier chip U3 form a constant current source circuit, wherein the resistance values and the precision of the mass resistors R4 to R7 of the constant current source are consistent. The resistor R8 and the resistor R9 are constant current value adjusting resistors output by the constant current source circuit, and play roles in coarse adjustment and fine adjustment. The operational amplifier model selects rail-to-rail output and low-noise operational amplifier.
The resistor R28 is a short-circuit resistor, and application conversion from a four-wire system to a three-wire system is realized. The resistors R11 to R14 and the operational amplifier chip U3 form a differential proportional amplifier circuit, the resistor R11 is equal to the resistor R12, the resistor R13 is equal to the resistor R14, and the amplification factor is the resistor R14/the resistor R11. The resistors R15 to R23 and the operational amplifier chip U3 form a subtraction circuit, wherein the rheostat R15 is adjustable, and can be replaced by a fixed-value resistor in a stable production process to further reduce the volume of the conditioning circuit board. The resistor R16 and the resistor R27 are used for secondarily adjusting the temperature signal voltage, and the amplification factor of the subtraction circuit is 1+ (resistor R20+ resistor R21)/(resistor R19+ (resistor R18// (resistor R15+ resistor R17))). The resistor R22 and the resistor R23 are used for adjusting output voltage, and the capacitor C5 and the capacitor C6 are used for filtering high-frequency interference.
Claims (5)
1. A0-5V output Pt100 temperature signal conditioning circuit is characterized by comprising a power supply circuit, a constant current source circuit and an acquisition zero setting circuit;
the power supply circuit is used for conditioning an input signal voltage Vi into a conditioning power supply output end of 12V through a three-terminal voltage-stabilizing chip U1 in cooperation with voltage stabilization of a voltage-stabilizing tube and filtering of an input and output capacitor so as to meet the condition that the conditioning power supply output end is more than 2 times of 5V of output voltage, and meanwhile, the conditioning output of the three-terminal voltage-stabilizing chip U1 is converted into 2.5V of reference voltage through a U2 precision reference voltage source chip U2 for zero setting;
the constant current source circuit is realized by constructing a positive and negative feedback resistor network through introducing a 2.5V reference voltage and through a 1/4 operational amplifier of an operational amplifier chip U3, and the resistor R8 and the resistor R9 realize coarse and fine adjustment of a constant current value;
the acquisition zero setting circuit is used for realizing a first-stage differential operational amplifier circuit and a second-quarter subtraction circuit through an amplifying circuit and a zero setting circuit which are formed by 2/4 operational amplifiers and 3/4 operational amplifiers in an operational amplifier chip U3; the amplification factor of the first-stage differential operational amplifier circuit is 4.5 times, and the differential input end parallel resistor R10 is used for realizing 12V output and prompting an open-circuit fault when the Pt100 platinum resistor has the open-circuit fault; the second-stage subtraction circuit is used for carrying out subtraction operation on the zeroing voltage formed by the temperature voltage signal in-phase proportional amplification circuit and the reverse-end precision reference voltage, and the amplification proportion is 5.4 times; and the two-stage operational amplifier circuits are provided with filter capacitors in feedback loops.
2. The 0-5V output Pt100 temperature signal conditioning circuit according to claim 1, characterized in that the power supply circuit comprises an input signal voltage Vi, a conditioning power supply output end, a reference voltage output end, a diode D1, a diode D2, a resistor R1, a resistor R2, a resistor R24, a resistor R25, a resistor R26, a three-terminal voltage-stabilizing chip U1, a precision reference voltage source chip U2, a capacitor C1 and a capacitor C2;
one end of the resistor R24 is connected to the input signal voltage Vi; the other end of the R24 is simultaneously connected with the cathode of the diode D1, the cathode of the diode D2, one end of the capacitor C1 and the first pin of the three-terminal voltage stabilizing chip U1; the second pin of the three-terminal voltage-stabilizing chip U1 is simultaneously connected with one end of the resistor R1 and one end of the resistor R2; a third pin of the three-terminal voltage-stabilizing chip U1 is simultaneously connected with the other end of the resistor R2, the output end of the conditioning power supply, one end of the capacitor C2 and one end of the resistor R25; the other end of the resistor R25 is connected with the resistor R26 and a first pin of the precision reference voltage source chip U2; a second pin of the precision reference voltage source chip U2 is connected with a reference voltage output end; the anode of the diode D1, the anode of the diode D2, the other end of the capacitor C1, the other end of the resistor R1, the other end of the capacitor C2, the other end of the resistor R26 and a third pin of the precision reference voltage source chip U2 are grounded;
the output end of the conditioning power supply is +12V, the output end of the reference voltage is +2.5V, the specification of a diode D1 and a diode D2 is 1N5246B, the resistance value of a resistor R1 is 2K omega, the resistance value of a resistor R2 is 240 omega, the resistance value of a resistor R24 is 1K omega, the resistance value of a resistor R25 is 5K omega, the resistance value of a resistor R26 is 24K omega, the specification of a three-end voltage stabilizing chip U1 is LM117H, the specification of a precision reference voltage source chip U2 is AD580UH, the capacitance of a capacitor C1 is 0.1 muF, and the capacitance of a capacitor C2 is 1 muF.
3. The 0-5V output Pt100 temperature signal conditioning circuit according to claim 2, characterized in that the constant current source circuit comprises a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a capacitor C3, a capacitor C4, an operational amplifier chip U3, a positive temperature indication Ti + and a negative temperature indication Ti-;
one end of the resistor R3 is connected with the output end of the precision reference voltage source chip U2, and the other end is connected with one end of the resistor R4; the other end of the resistor R4 is simultaneously connected with a third pin of the operational amplifier chip U3 and one end of the resistor R7; the other end of the resistor R7 is simultaneously connected with one end of a resistor R8, one end of a resistor R9, positive temperature indication Ti + and one end of a capacitor C4; the other end of the resistor R8 is simultaneously connected with the other end of the resistor R9, a first pin of the operational amplifier chip U3 and one end of the resistor R6; the other end of the resistor R6 is simultaneously connected with a second pin of the operational amplifier chip U3 and one end of the resistor R5; a fourth pin of the operational amplifier chip U3 is simultaneously connected with the output end of the conditioning power supply and one end of the capacitor C3; the other end of the resistor R5, the eleventh pin of the operational amplifier chip U3 and the other end of the capacitor C3 are grounded; the other end of the capacitor C4 is connected with a negative temperature indicator Ti < - > and is grounded;
the resistance of the resistor R3 is 1.54K omega, the resistance of the resistor R4 is 221K omega, the resistance of the resistor R5 is 221K omega, the resistance of the resistor R6 is 221K omega, the resistance of the resistor R7 is 221K omega, the resistance of the resistor R8 is 1K omega, the resistance of the resistor R9 is 2.2M omega, the capacitance of the capacitor C3 is 0.1 muF, the capacitance of the capacitor C4 is 1 muF, and the specification of the operational amplifier chip U3 is OPA4703 UA.
4. The 0-5V output Pt100 temperature signal conditioning circuit according To claim 3, characterized in that the acquisition zeroing circuit comprises a resistor R28, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a rheostat R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R27, a capacitor C5, a capacitor C6, an operational amplifier chip U3, a temperature measuring element output port To +, a temperature measuring element output port To-and an output port Vo;
one end of the resistor R28 is connected with the positive temperature indicator Ti +, and the other end is simultaneously connected with one end of the network interface To-, the resistor R10 and one end of the resistor R11; the other end of the resistor R10 is simultaneously connected with the network interface To + and one end of the resistor R12; the other end of the resistor R11 is simultaneously connected with one end of the capacitor C5, one end of the resistor R14 and the sixth pin of the operational amplifier chip U3; the other end of the resistor R12 is simultaneously connected with one end of the resistor R13 and the fifth pin of the operational amplifier chip U3; the other end of the resistor R13 is connected with an eleventh pin of the operational amplifier chip U3; the other end of the capacitor C5 is simultaneously connected with the other end of the resistor R14, a seventh pin of the operational amplifier chip U3 and one end of the resistor R16; the other end of the resistor R16 is simultaneously connected with the tenth pin of the operational amplifier chip U3 and one end of the resistor R27; the other end of the resistor R27 is connected with an eleventh pin of the operational amplifier chip U3; an eighth pin of the operational amplifier chip U3 is simultaneously connected with one end of the resistor R21, one end of the resistor R22 and one end of the capacitor C6; the other end of the resistor R22 is simultaneously connected with one ends of the output ports Vo and R23; the other end of R23 is grounded; the other end of the resistor R21 is connected with the other end of the resistor R20; the other end of the capacitor C6 is simultaneously connected with one end of the resistor R19, one end of the resistor R20 and the ninth pin of the operational amplifier chip U3; the other end of the resistor R19 is simultaneously connected with one end of the resistor R18 and a second pin of the rheostat R15; the other end of the resistor R18 is connected with a reference voltage output end; a first pin of the rheostat R15 is connected with one end of the resistor R17; the other end of the resistor R17 is grounded;
the resistance value of the resistor R28 is 0 Ω, the resistance value of the resistor R10 is 680K Ω, the resistance value of the resistor R11 is 221K Ω, the resistance value of the resistor R12 is 221K Ω, the resistance value of the resistor R13 is 1M Ω, the resistance value of the resistor R14 is 1M Ω, the maximum resistance value of the varistor R15 is 1K Ω, the resistance value of the resistor R16 is 6.81K Ω, the resistance value of the resistor R17 is 16.5K Ω, the resistance value of the resistor R18 is 24K Ω, the resistance value of the resistor R19 is 1M Ω, the resistance value of the resistor R20 is 2.2M Ω, the resistance value of the resistor R21 is 2.2M Ω, the resistance value of the resistor R22 is 240 Ω, the resistance value of the resistor R23 is 1K Ω, the resistance value of the resistor R27 is 1M Ω, the capacitance value of the capacitor C5 is 33nF, and the capacitance value of the capacitor C6 is 0..
5. The 0-5V output Pt100 temperature signal conditioning circuit of claim 4, wherein the 0-5V output Pt100 temperature signal conditioning circuit further comprises a voltage follower circuit; the voltage follower circuit comprises an operational amplifier chip U3 and an output port Vo 2; a twelfth pin of the operational amplifier chip U3 is connected with the output port Vo; the fourteenth pin of the operational amplifier chip U3 is connected to the output port Vo2 and the thirteenth pin of the operational amplifier chip U3.
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| CN201911201995.7A CN110940435A (en) | 2019-11-29 | 2019-11-29 | 0 ~ 5V output Pt100 temperature signal conditioning circuit |
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| CN201911201995.7A CN110940435A (en) | 2019-11-29 | 2019-11-29 | 0 ~ 5V output Pt100 temperature signal conditioning circuit |
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| US20040081224A1 (en) * | 2002-10-24 | 2004-04-29 | Mitsubishi Denki Kabushiki Kaisha | Device for measuring temperature of semiconductor integrated circuit |
| CN102426066A (en) * | 2011-09-26 | 2012-04-25 | 天津成科自动化工程技术有限公司 | Switching detection circuit using multi-channel PT100 thermistors as temperature sensor |
| CN203258881U (en) * | 2013-03-15 | 2013-10-30 | 华中科技大学文华学院 | Solar water heater |
| CN205940790U (en) * | 2016-08-01 | 2017-02-08 | 湖南省耐为数控技术有限公司 | A circuit for motor temperature precision measurement |
| CN207231661U (en) * | 2017-10-17 | 2018-04-13 | 四川华信智创科技有限公司 | The voltage conversion transmission circuit of temperature sensor is done using platinum resistance |
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2019
- 2019-11-29 CN CN201911201995.7A patent/CN110940435A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040081224A1 (en) * | 2002-10-24 | 2004-04-29 | Mitsubishi Denki Kabushiki Kaisha | Device for measuring temperature of semiconductor integrated circuit |
| CN102426066A (en) * | 2011-09-26 | 2012-04-25 | 天津成科自动化工程技术有限公司 | Switching detection circuit using multi-channel PT100 thermistors as temperature sensor |
| CN203258881U (en) * | 2013-03-15 | 2013-10-30 | 华中科技大学文华学院 | Solar water heater |
| CN205940790U (en) * | 2016-08-01 | 2017-02-08 | 湖南省耐为数控技术有限公司 | A circuit for motor temperature precision measurement |
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