CN211317573U - Temperature data acquisition circuit with isolation function - Google Patents
Temperature data acquisition circuit with isolation function Download PDFInfo
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- CN211317573U CN211317573U CN201922101244.XU CN201922101244U CN211317573U CN 211317573 U CN211317573 U CN 211317573U CN 201922101244 U CN201922101244 U CN 201922101244U CN 211317573 U CN211317573 U CN 211317573U
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Abstract
The utility model discloses a temperature data acquisition circuit with isolation function, which comprises a temperature data acquisition circuit, a resistance voltage division circuit, a first operational amplifier processing circuit, an optical coupling isolation circuit, a second operational amplifier processing circuit and an MCU conversion control circuit which are connected in sequence; the temperature data acquisition circuit measures temperature data and converts the temperature data into a direct current voltage signal; the resistance voltage division circuit is used for carrying out voltage division processing on the direct-current voltage signal; the first operational amplifier processing circuit performs voltage stabilization and amplification on the direct current voltage subjected to voltage division processing; the optical coupling isolation circuit feeds the acquired voltage back to the second operational amplifier processing circuit in an isolation mode; the second operational amplifier processing circuit performs voltage stabilization amplification processing on the voltage fed back by the optical coupling isolation circuit; the MCU conversion control circuit acquires, calculates and converts the voltage of the second operational amplifier processing circuit into corresponding temperature. The utility model discloses measure that the linearity is good, measurement accuracy is high, the circuit is simple, the interference killing feature is strong, low cost, application prospect are extensive.
Description
Technical Field
The utility model relates to a switching power supply technical field, specifically speaking relates to a temperature data acquisition circuit with isolation function.
Background
In a temperature environment acquisition terminal function system, analog acquisition of temperature and humidity is often used, and in order to reduce the influence of environmental noise on a test circuit and ensure the accuracy of a measurement result, a tested circuit and the test circuit are often electrically isolated. The temperature data acquisition circuit in the prior art generally comprises a temperature acquisition converter and an MCU (micro control unit), and the circuit is simple but not electrically isolated from other circuits, and can influence the performances of other parts of the terminal when certain interference is introduced into the periphery. Therefore, isolation must be used, which requires a photo coupler, and a general photo coupler has a nonlinear current transfer characteristic, which is not problematic for the transfer of digital quantity and switching quantity, but has poor transfer accuracy for analog quantity.
Disclosure of Invention
An object of the utility model is to provide a temperature data acquisition circuit, especially a temperature data acquisition circuit with isolation function to current temperature data acquisition circuit's not enough.
In order to achieve the above purpose, the utility model discloses the technical scheme who takes includes:
a temperature data acquisition circuit with an isolation function comprises a temperature data acquisition circuit, a resistance voltage division circuit, a first operational amplifier processing circuit, an optical coupling isolation circuit, a second operational amplifier processing circuit and an MCU conversion control circuit which are connected in sequence;
the temperature data acquisition circuit is used for measuring temperature data in a measured environment and converting the measured temperature data into a direct-current voltage signal; the resistance voltage division circuit is used for carrying out voltage division processing on the direct-current voltage signal measured by the temperature data acquisition circuit; the first operational amplifier processing circuit is used for performing voltage stabilization and amplification processing on the direct-current voltage subjected to voltage division processing; the optical coupling isolation circuit is used for feeding back the acquired voltage to the second operational amplifier processing circuit in an isolation mode; the second operational amplifier processing circuit is used for carrying out voltage stabilization and amplification processing on the voltage fed back by the optical coupling isolation circuit; the MCU conversion control circuit is used for acquiring and converting the voltage of the second operational amplifier processing circuit into corresponding temperature.
Furthermore, the temperature DATA acquisition circuit comprises a temperature DATA acquisition sensor U1, wherein a 2-pin end of the temperature DATA acquisition sensor U1 is connected with a VCC1 power supply end, a 3-pin end of the temperature DATA acquisition sensor U1 is connected with a GND ground end for power supply, and a 4-pin end DATA end and a 1-pin end SCK end of the temperature DATA acquisition sensor U1 are respectively connected with the resistance voltage division circuit.
Further, the resistance voltage dividing circuit comprises a resistor R1 and a resistor R2 which are connected, one end of the resistor R1 is connected to the DATA end of the 4-pin end of the temperature DATA acquisition sensor U1, one end of the resistor R2 is connected to the SCK end of the 1-pin end of the temperature DATA acquisition sensor U1, a common end of the resistor R1 and the resistor R2 is connected to the first operational amplifier processing circuit, and the resistor R1 and the resistor R2 are used for dividing the voltage signal measured by the temperature DATA acquisition circuit.
Further, the first operational amplifier processing circuit comprises an operational amplifier U2 and a capacitor C1 which are connected in parallel, a pin 5 and a pin 2 of the operational amplifier U2 are respectively connected with a VCC power supply end and a GND ground end of a power supply, a pin 1 of a same-direction input end of the operational amplifier U2 is connected with a ground end of the power supply, a pin 3 of a reverse input end of the operational amplifier U2 is connected with a common end of a resistor R1 and a resistor R2, and a pin 4 of an output end of the operational amplifier U2 is connected with an external resistor R3 and the optical coupling isolation circuit.
Further, the optical coupler isolation circuit comprises an optical coupler U3, and the optical coupler U3 comprises a light emitting diode LED, a photodiode PD1 and a photodiode PD 2;
a pin 1 at the negative end of the light-emitting diode LED is connected with the other end of the resistor R3, and a pin 2 at the positive end of the light-emitting diode LED is connected with a VCC power supply end;
a negative end pin 3 of the photodiode PD1 is connected with a reverse input end pin 3 of the first operational amplifier processing circuit, and a positive end pin 4 of the photodiode PD1 is connected with a pin 1 end SCK end in the temperature data acquisition circuit;
and the positive terminal 5 pin and the negative terminal 6 pin of the photodiode PD2 are respectively connected with the second operational amplifier processing circuit.
Further, the second operational amplifier processing circuit comprises an operational amplifier U4, a resistor R4 and a capacitor C2 which are connected in parallel;
a pin 5 of the operational amplifier U4 is connected with the MCU conversion control circuit, and a pin 2 of the operational amplifier U4 is connected with a GND2 pin;
the inverting input end 3 pin of the operational amplifier U4 is respectively connected with the negative end 6 pin of the photodiode PD2, the common end of the resistor R4 and the capacitor C2, the equidirectional input end 1 pin of the operational amplifier U4 is respectively connected with the positive end 5 pin of the photodiode PD2 and the GND2 pin, and the output end 4 pin of the operational amplifier processing circuit is respectively connected with the resistor R4, the capacitor C2 and the MCU conversion control circuit.
Further, the MCU conversion control circuit comprises a single chip microcomputer U5, a VCC2 end of the single chip microcomputer U5 is connected with a VCC2 power supply end of secondary side power supply, a GND2 end is connected with a GND2 ground end of the single chip microcomputer U5, and an AD1 port in the MCU conversion control circuit is connected with the 4 pins of the output end of the operational amplifier processing circuit.
Preferably, the model of the temperature data acquisition sensor U1 is SHT 75.
Preferably, the models of the operational amplifier U4 and the operational amplifier U2 are LMV321 chips.
The utility model discloses a following technological effect has:
the utility model provides a temperature data acquisition circuit with isolation function, the temperature analog volume that gathers when temperature sensor is through fortune after enlargiing lug connection to opto-coupler isolation, through fortune after enlargiing convey AD sense terminal, then can calculate initial measured ambient temperature value through corresponding proportional formula, the utility model discloses measure that the linearity is good, measurement accuracy is high, the circuit is simple, can resist and hit multiple external factor interference, interference killing feature is strong, low cost, application prospect are extensive, and high pressure resistant reaches the purpose of the temperature data acquisition of isolation moreover.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention;
the reference numerals in the figures denote: 1. a temperature data acquisition circuit; 2. a resistance voltage-dividing circuit; 3. a first operational amplifier processing circuit; 4. an opto-coupler isolation circuit; 5. a second operational amplifier processing circuit; 6. and the MCU conversion control circuit.
Detailed Description
The invention will be described in further detail with reference to the accompanying drawings:
with reference to fig. 1, the utility model provides a temperature data acquisition circuit 1 with isolation function, including temperature data acquisition circuit 1, resistance bleeder circuit 2, first operational amplifier processing circuit 3, opto-coupler isolation circuit 4, second operational amplifier processing circuit 5 and MCU conversion control circuit 6 that connect gradually;
the temperature data acquisition circuit 1 is used for measuring temperature data in a measured environment and converting the measured temperature data into corresponding direct-current voltage signals; the resistance voltage division circuit 2 is used for carrying out voltage division processing on the direct-current voltage signal measured by the temperature data acquisition circuit 1; the first operational amplifier processing circuit 3 is used for performing voltage stabilization and amplification processing on the direct-current voltage subjected to voltage division processing; the optical coupling isolation circuit 4 is used for feeding back the acquired voltage to the second operational amplifier processing circuit 5 in an isolation mode; the second operational amplifier processing circuit 5 is used for performing voltage stabilization and amplification processing on the voltage fed back by the optical coupling isolation circuit 4; the MCU control circuit is used for collecting and converting the voltage processed by the second operational amplifier processing circuit 5 into corresponding temperature by using an AD1 analog port of the singlechip.
The temperature DATA acquisition circuit 1 comprises a temperature DATA acquisition sensor U1, a 2-pin end of the temperature DATA acquisition sensor U1 is connected with a VCC1 power supply end, a 3-pin end of the temperature DATA acquisition sensor U1 is connected with a GND ground end for power supply, a 4-pin DATA end and a 1-pin SCK end of the temperature DATA acquisition sensor U1 are respectively connected with the resistance voltage division circuit 2, the DATA is a bidirectional serial DATA line, and the SCK end is used for inputting a serial clock. The model of the temperature data acquisition sensor U1 is SHT 75.
The resistance voltage dividing circuit 2 comprises a resistor R1 and a resistor R2 which are connected, one end of the resistor R1 is connected with a 4-pin DATA end of a temperature DATA acquisition sensor U1 of the temperature DATA acquisition circuit 1, one end of the resistor R2 is connected with a 1-pin SCK end of a temperature DATA acquisition sensor U1 of the temperature DATA acquisition circuit 1, a common end of the resistor R1 and the resistor R2 is connected with the first operational amplifier processing circuit 3, and the resistor R1 and the resistor R2 are used for dividing voltage signals measured by the temperature DATA acquisition circuit 1 to enable the voltage to be lower than 5V.
The first operational amplifier processing circuit 3 comprises an operational amplifier U2 and a capacitor C1 which are connected in parallel, wherein a pin 5 and a pin 2 of the operational amplifier U2 are respectively connected with a VCC power supply end and a GND ground end of a power supply, a pin 1 of a homodromous input end of the operational amplifier U2 is connected with a ground end of the power supply, a pin 3 of a reverse input end of the operational amplifier U2 is connected with a common end of a resistor R1 and a resistor R2 in a resistor voltage division circuit 2, a pin 4 of an output end of the operational amplifier U2 is connected with an external resistor R3 and an optical coupling isolation circuit 4, and the operational amplifier U2 is used for measuring the voltage divided by the resistor voltage division circuit 2 and forming a negative feedback signal. The capacitor C1 is used to improve the stability of the circuit.
The optical coupling isolation circuit 4 comprises an optical coupling U3, the optical coupling U3 comprises a light emitting diode LED, a photodiode PD1 and a photodiode PD2, the other end of a negative end 1 pin of the light emitting diode LED of the optical coupling U3 is connected with a resistor R3, a positive end 2 pin of the light emitting diode LED is connected with a VCC power supply end, a negative end 3 pin of a photodiode PD1 is connected with a reverse input end 3 pin of a first operational amplifier processing circuit 3, a positive end 4 pin of the photodiode PD1 is connected with a pin 1 end SCK end in a temperature data acquisition circuit 1, a positive end 5 pin and a negative end 6 pin of the photodiode PD2 are respectively connected with a second operational amplifier processing circuit 5, the light emitting diode LED in the optical coupling isolation circuit 4, the photodiode PD1 and the first operational amplifier processing circuit 3 form an input part of a measuring circuitWhen the collected voltage changes, the current I of the light emitting diode LED is under the action of the first operational amplifier processing circuit 3FWith the adjustment, the physical structure of the optical coupling isolation circuit 4 determines that the photodiode PD1 is linearly proportional to the light emitting diode LED, so the current I flowing through the photodiode PD1PD1Photodiode PD2 is in strict proportion to photodiode PD1 as input voltage changes, and I is the samePD2Following the input voltage variation, an isolated feedback is formed.
The model of the optocoupler U3 is HCNR201, the optocoupler U3 is composed of a high-performance light emitting diode LED and photodiodes PD1 and PD2 which have a strict proportional relation, and the principle diagram of the optocoupler isolation chip HCNR201 is shown in figure 1. The light emitted by the LED is received by PD1, PD2, wherein PD2 is used to generate an output current; the PD1 is used for feedback to compensate the on-current of the LED and improve the linearity and temperature characteristics between the input and output circuits. The structure ensures high stability and high linearity of the linear optical coupler.
The second operational amplifier processing circuit 5 comprises an operational amplifier U4, a resistor R4 and a capacitor C2 which are connected in parallel, wherein a pin 5 of the operational amplifier U4 is connected with the MCU conversion control circuit 6, and a pin 2 of the operational amplifier U4 is connected with a pin GND 2; the inverting input end pin 3 of the operational amplifier U4 is respectively connected with the negative end pin 6 of the photodiode PD2, the common end of the resistor R4 and the capacitor C2, the same-direction input end pin 1 of the operational amplifier U4 is respectively connected with the positive end pin 5 of the photodiode PD2 and the GND2, and the output end pin 4 of the operational amplifier processing circuit is respectively connected with the resistor R4, the capacitor C2 and the MCU conversion control circuit 6.
The second operational amplifier processing circuit 5 is used for converting the I photodiode PD2 into an output voltage, and finally, a precise linear relation between the output voltage and the input temperature acquisition voltage is realized. The capacitor C2 has the compensation function, and is used for improving the stability of the circuit, reducing the output ripple noise of the circuit and limiting the working bandwidth in the circuit to be about 10 KHz.
As an embodiment, the operational amplifier U2 and the operational amplifier U4 of the first operational amplifier processing circuit 3 and the second operational amplifier processing circuit 5 both use LMV321 chips.
The MCU conversion control circuit 6 comprises a single chip microcomputer U5, a VCC2 end in the MCU conversion control circuit 6 is connected with a VCC2 power supply end of secondary side power supply, a GND2 end and a GND2 ground end of the single chip microcomputer U5, an AD1 port in the MCU conversion control circuit 6 is connected with an output end 4 pin of the operational amplifier processing circuit, and the MCU conversion control circuit 6 is used for collecting, operating and converting voltage processed by the operational amplifier processing circuit into corresponding temperature by using an AD1 analog port of the single chip microcomputer.
After the acquired temperature data signals are subjected to voltage division through the resistance voltage division circuit 2, the divided signals are connected with the operational amplifier U2, then the output end of the operational amplifier is connected with the optical coupling isolation chip HCNR201, and the output end of the operational amplifier is connected with the AD1 port of the MCU after the operational amplifier outputs U4, so that the analog voltage value is measured, and the temperature value of the detected environment is calculated.
When the temperature changes along with the measured temperature, the current I of the LEDFThe physical characteristics of the optical coupler determine that the PD1 is in linear proportion with the LED along with the change and adjustment of the collected temperature data, the linearity is as high as 0.02%, and therefore the current I flowing through the PD1PD1The current IPD2 of the PD2 changes along with the change of the temperature and the current I on the PD2 is changed through the operational amplifier U4 and the resistor R4 according to the change of the temperature and the change of the PD2 and the PD1 in strict direct proportion relationPD2And converting the analog quantity into required output analog quantity, and finally converting the output analog quantity through a control circuit of the MCU, so that the detected temperature and the measured environment temperature are acquired in an isolated manner.
And the operational amplifier U2 and the operational amplifier U4 both adopt LMV321 chips, so that the precision is high. A compensation capacitor C2 is connected between the inverting input end and the output end of the operational amplifier U4 and is used for improving the stability of the circuit, reducing the output noise of the circuit and limiting the working bandwidth of the circuit.
The above description is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can change or replace the present invention without creative efforts within the technical scope of the present invention.
Claims (9)
1. A temperature data acquisition circuit with an isolation function is characterized by comprising a temperature data acquisition circuit (1), a resistance voltage division circuit (2), a first operational amplifier processing circuit (3), an optical coupling isolation circuit (4), a second operational amplifier processing circuit (5) and an MCU conversion control circuit (6) which are sequentially connected;
the temperature data acquisition circuit (1) is used for measuring temperature data in a measured environment and converting the measured temperature data into a direct-current voltage signal; the resistance voltage dividing circuit (2) is used for dividing the direct-current voltage signal measured by the temperature data acquisition circuit (1); the first operational amplifier processing circuit (3) is used for performing voltage stabilization and amplification processing on the direct-current voltage subjected to voltage division processing; the optical coupling isolation circuit (4) is used for feeding back the collected voltage to the second operational amplifier processing circuit (5) in an isolation mode; the second operational amplifier processing circuit (5) is used for performing voltage stabilization and amplification processing on the voltage fed back by the optical coupling isolation circuit (4); the MCU conversion control circuit (6) is used for collecting and operating the voltage of the second operational amplifier processing circuit (5) and converting the voltage into corresponding temperature.
2. The temperature DATA acquisition circuit with isolation function according to claim 1, wherein the temperature DATA acquisition circuit (1) comprises a temperature DATA acquisition sensor U1, a 2-pin terminal of the temperature DATA acquisition sensor U1 is connected to a VCC1 power supply terminal, a 3-pin terminal of the temperature DATA acquisition sensor U1 is connected to a GND ground terminal for power supply, and a 4-pin terminal DATA terminal and a 1-pin terminal SCK terminal of the temperature DATA acquisition sensor U1 are respectively connected to the resistance voltage division circuit (2).
3. The temperature DATA acquisition circuit with isolation function according to claim 2, wherein the resistance voltage divider circuit (2) comprises a resistor R1 and a resistor R2 connected to each other, one end of the resistor R1 is connected to the DATA terminal of the 4-pin terminal of the temperature DATA acquisition sensor U1, one end of the resistor R2 is connected to the SCK terminal of the 1-pin terminal of the temperature DATA acquisition sensor U1, the common terminal of the resistor R1 and the resistor R2 is connected to the first operational amplifier processing circuit (3), and the resistor R1 and the resistor R2 are used for dividing the voltage signal measured by the temperature DATA acquisition circuit (1).
4. The temperature data acquisition circuit with isolation function according to claim 3, wherein the first operational amplifier processing circuit (3) comprises an operational amplifier U2 and a capacitor C1 connected in parallel, a pin 5 and a pin 2 of the operational amplifier U2 are respectively connected to a VCC power supply terminal and a GND ground terminal of a power supply, a pin 1 of a homodromous input terminal of the operational amplifier U2 is connected to a ground terminal of the power supply, a pin 3 of an inverting input terminal of the operational amplifier U2 is connected to a common terminal of the resistor R1 and the resistor R2, and a pin 4 of an output terminal of the operational amplifier U2 is connected to the optical coupling isolation circuit (4) through an external resistor R3.
5. The temperature data acquisition circuit with isolation function according to claim 4, wherein the optical coupling isolation circuit (4) comprises an optical coupler U3, the optical coupler U3 comprises a light emitting diode LED, a photodiode PD1 and a photodiode PD 2;
a pin 1 at the negative end of the light-emitting diode LED is connected with the other end of the resistor R3, and a pin 2 at the positive end of the light-emitting diode LED is connected with a VCC power supply end;
a negative end pin 3 of the photodiode PD1 is connected with a reverse input end pin 3 of the first operational amplifier processing circuit (3), and a positive end pin 4 of the photodiode PD1 is connected with a pin 1 end SCK end in the temperature data acquisition circuit (1);
and the positive terminal 5 pin and the negative terminal 6 pin of the photodiode PD2 are respectively connected with the second operational amplifier processing circuit (5).
6. The temperature data acquisition circuit with isolation function according to claim 5, wherein the second operational amplifier processing circuit (5) comprises an operational amplifier U4, a resistor R4 and a capacitor C2 connected in parallel;
a pin 5 of the operational amplifier U4 is connected with the MCU conversion control circuit (6), and a pin 2 of the operational amplifier U4 is connected with a GND2 pin;
the inverting input end pin 3 of the operational amplifier U4 is respectively connected with the negative end pin 6 of the photodiode PD2, the common end of the resistor R4 and the capacitor C2, the equidirectional input end pin 1 of the operational amplifier U4 is respectively connected with the positive end pin 5 and the GND2 of the photodiode PD2, and the output end pin 4 of the operational amplifier processing circuit is respectively connected with the resistor R4, the capacitor C2 and the MCU conversion control circuit (6).
7. The temperature data acquisition circuit with the isolation function according to claim 6, wherein the MCU conversion control circuit (6) comprises a single chip microcomputer U5, a VCC2 terminal of the single chip microcomputer U5 is connected with a VCC2 power supply terminal of secondary side power supply, a GND2 terminal is connected with a GND2 ground terminal of the single chip microcomputer U5, and an AD1 port in the MCU conversion control circuit (6) is connected with the output terminal 4 pin of the operational amplifier processing circuit.
8. The isolated temperature data acquisition circuit of claim 2, wherein the temperature data acquisition sensor is a type SHT75, U1.
9. The isolated temperature data acquisition circuit of claim 6, wherein the operational amplifier U4 and the operational amplifier U2 are both LMV321 chips.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922101244.XU CN211317573U (en) | 2019-11-28 | 2019-11-28 | Temperature data acquisition circuit with isolation function |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922101244.XU CN211317573U (en) | 2019-11-28 | 2019-11-28 | Temperature data acquisition circuit with isolation function |
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| CN211317573U true CN211317573U (en) | 2020-08-21 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117589323A (en) * | 2024-01-19 | 2024-02-23 | 常州通宝光电股份有限公司 | High-voltage isolation area temperature acquisition circuit |
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2019
- 2019-11-28 CN CN201922101244.XU patent/CN211317573U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117589323A (en) * | 2024-01-19 | 2024-02-23 | 常州通宝光电股份有限公司 | High-voltage isolation area temperature acquisition circuit |
| CN117589323B (en) * | 2024-01-19 | 2024-03-26 | 常州通宝光电股份有限公司 | High-voltage isolation area temperature acquisition circuit |
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