CN220105580U - Constant current source circuit of carbon resistance temperature sensor for low-temperature measurement - Google Patents
Constant current source circuit of carbon resistance temperature sensor for low-temperature measurement Download PDFInfo
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- CN220105580U CN220105580U CN202321450914.9U CN202321450914U CN220105580U CN 220105580 U CN220105580 U CN 220105580U CN 202321450914 U CN202321450914 U CN 202321450914U CN 220105580 U CN220105580 U CN 220105580U
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 20
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 20
- 238000009529 body temperature measurement Methods 0.000 title claims abstract description 15
- 239000003990 capacitor Substances 0.000 claims abstract description 143
- 230000000087 stabilizing effect Effects 0.000 claims description 89
- 238000006243 chemical reaction Methods 0.000 claims description 49
- 230000005284 excitation Effects 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 7
- 238000005259 measurement Methods 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- 229910052734 helium Inorganic materials 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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Abstract
A constant current source circuit of a carbon resistance temperature sensor for low-temperature measurement belongs to the technical field of contact low-temperature measurement and solves the problem of inaccurate low-temperature measurement caused by joule heat generated by the carbon resistance temperature sensor; comprising the following steps: the first operational amplifier U8, the second operational amplifier U9, the capacitor C123, the capacitor C124, the resistor R23 and the power supply circuit; the constant current source circuit outputs excitation current by adopting the first operational amplifier U8, and the second operational amplifier U9 collects the output excitation current in real time for feedback adjustment, so that the stability and reliability of the output excitation current are ensured; the first operational amplifier U8 adopts an operational amplifier with a high common mode rejection ratio, so that the anti-interference performance of low-temperature measurement is improved, and the precision is higher; the power supply circuit adopts a chopper type 220-12/AC-DC module, and an FC-LX1D filter is arranged in front of the chopper type 220-12/AC-DC module, so that the noise of the power supply circuit is reduced, and the power supply circuit is suitable for occasions sensitive to the noise.
Description
Technical Field
The utility model belongs to the technical field of contact type low-temperature measurement, and relates to a constant current source circuit of a carbon resistance temperature sensor for low-temperature measurement.
Background
Carbon resistance temperature sensors are often used to measure the temperature of liquid helium (5 to 80K) due to their extremely high sensitivity. The carbon resistance temperature sensor requires an external power supply to be driven to operate. Since the carbon resistance temperature sensor has a resistance value of several kiloohms at low temperature, when the current is larger, the self-heating power of the carbon resistance temperature sensor is higher, joule heat is generated, and when the joule heat is too large, a larger measurement error is brought, and even the measurement error is caused in serious cases, so that the carbon resistance temperature sensor needs to be driven by small current. It is therefore desirable to design a stable and reliable constant current source to limit joule heating generated by the carbon resistance temperature sensor.
Disclosure of Invention
The utility model aims to design a stable and reliable constant current source so as to solve the problem of inaccurate low-temperature measurement caused by joule heat generated by a carbon resistance temperature sensor.
The utility model solves the technical problems through the following technical scheme:
a carbon resistance temperature sensor constant current source circuit for cryogenic measurement, comprising: the first operational amplifier U8, the second operational amplifier U9, the capacitor C123, the capacitor C124, the resistor R23 and the power supply circuit; 1 of the first operational amplifier U8 # Pin is grounded, 4 of the first operational amplifier U8 # Pin is connected with reference voltage, 8 of first operational amplifier U8 # Pin and 5 of first operational amplifier U8 # Pins are connected with a power supply circuit, one end of a capacitor C123 is connected with 8 of a first operational amplifier U8 # The other end of the capacitor C123 is grounded, and one end of the capacitor C124 is connected with 5 of the first operational amplifier U8 # Pin is connected, the other end of the capacitor C124 is grounded, 7 of the first operational amplifier U8 # The pin is connected with one end of a resistor R23, and the other end of the resistor R23 is connected with 3 of a second operational amplifier U9 # Pin connection, 4 of second operational amplifier U9 # Pin and 7 of second operational amplifier U9 # Pins are connected with a power supply circuit, 6 of a second operational amplifier U9 # Pin 6 with first op amp U8 # Pin connection, 2 of second operational amplifier U9 # Pin 6 with second operational amplifier U9 # The pins are connected; resistor R23 and 3 of second operational amplifier U9 # The common point of connection of the pins is used as the output end of the constant current source circuit.
Further, the model of the first operational amplifier U8 is AD8221, and the model of the second operational amplifier U9 is AD8638.
Further, the power supply circuit includes: a first voltage conversion circuit, a second voltage conversion circuit, a third voltage conversion circuit; the input end of the first voltage conversion circuit is connected with a 220V alternating current power supply, and the output end of the first voltage conversion circuit is respectively connected with the second voltage conversion circuit and the third voltage conversion circuit; 8 of the first operational amplifier U8 # The pin is connected with the output end of the second voltage conversion circuit, 5 of the first operational amplifier U8 # The pin is connected with the output end of the third voltage conversion circuit; 7 of the second operational amplifier U9 # The pin is connected with the output end of the second voltage conversion circuit and 4 of the second operational amplifier U9 # The pin is connected with the output end of the third voltage conversion circuit.
Further, the first voltage conversion circuit includes: step-down chopper module V1, filter V2, fuse F1, electrolytic capacitor CE2, capacitor C54, capacitor C55, zener diode TVS9, zener diode TVS10; 3 of the filter V2 # Pin is connected with the live wire of 220V alternating current power supply, 2 of filter V2 # The pin is connected with the zero line of 220V alternating current power supply, 1 of the filter V2 # Pin is grounded, 4 of the filter V2 # Pin and 3 of step-down chopper module V1 # Pin connection, 5 of filter V2 # Pin and step-down chopper module V1 2 # Pin connection, 1 of filter V2 # The pin is grounded, and the cathode of the electrolytic capacitor CE1 is connected with 4 of the buck chopper module V1 # Pin, positive electrode of electrolytic capacitor CE1 is connected with 6 of step-down chopper module V1 # Pin, cathode of electrolytic capacitor CE2 is connected with 6 of step-down chopper module V1 # Pin, positive electrode of electrolytic capacitor CE2 is connected with 8 of step-down chopper module V1 # Pin, two ends of capacitor C54 are respectively connected with 4 of step-down chopper module V1 # 6 of pin and step-down chopper module V1 # Pin, two ends of capacitor C55 are respectively connected with 6 of step-down chopper module V1 # Pin and step-down chopper V1 8 # Pin, step-down chopper module V1 6 # The pin is grounded, one end of the voltage stabilizing diode TVS9 and 4 of the step-down chopper module V1 # Pin connection, another voltage stabilizing diode TVS9One end of the voltage stabilizing diode TVS10 is grounded and the other end of the voltage reducing chopper module V1 is grounded # The other end of the voltage stabilizing diode TVS10 is grounded, and the pin is connected with 8 of the step-down chopper module V1 # The pin is used as the output end of the +12V power supply and is connected with the input end of the second voltage conversion circuit, and the 4 of the buck chopper module V1 # The pin is used as the output end of the-12V power supply and is connected with the input end of the third voltage conversion circuit.
Further, the step-down chopper module V1 adopts a chopper type 220-12/AC-DC module, and the filter V2 adopts an FC-LX1D filter.
Further, the second voltage conversion circuit includes: the first linear voltage stabilizing chip V3, the capacitor C56, the capacitor C57, the capacitor C58, the capacitor C59, the capacitor C60, the capacitor C61, the resistor R30 and the resistor R31; 13 of the first linear voltage stabilizing chip V3 # Pins, 15 # Pins, 16 # The pins are connected together and then connected with the output end of the +12V power supply of the first voltage conversion circuit, one end of the capacitor C58 is connected with 13 of the first linear voltage stabilizing chip V3 # The other end of the pin and the capacitor C58 is grounded, and one end of the capacitor C59 is connected with 13 of the first linear voltage stabilizing chip V3 # The other end of the pin and the capacitor C59 is grounded, one end of the capacitor C60 and one end of the capacitor C61 are connected together and then connected with 14 of the first linear voltage stabilizing chip V3 # The other ends of the pin, the capacitor C60 and the capacitor C61 are grounded, and after the resistor R30 and the resistor R31 are connected in series, the non-series end of the resistor R30 and 1 of the first linear voltage stabilizing chip V3 # Pin connection, non-series grounding of the resistor R31, and 3 of the first linear voltage stabilizing chip V3 connected with the series common point of the resistor R30 and the resistor R31 # Pin, one of the parallel common terminals of the capacitor C56 and the capacitor C57 is connected in parallel with 1 of the first linear voltage stabilizing chip V3 # Pin, another parallel common ground, 1 of first linear voltage stabilizing chip V3 # Pins and 20 # Pins are connected together, 6 of the first linear voltage stabilizing chip V3 # Pins, 7 # Pin and 10 # Pin grounding, 1 of first linear voltage stabilizing chip V3 # The pin is used as the +5V power supply output end of the first linear voltage stabilizing chip V3.
Further, the model of the first linear voltage stabilizing chip V3 is TPS7a4701.
Further, the third voltage conversion circuit includes: the second linear voltage stabilizing chip V4, a capacitor C62, a capacitor C63, a capacitor C64, a capacitor C65, a capacitor C66, a capacitor C67, a capacitor C68, a resistor R32 and a resistor R33; 13 of the second linear voltage stabilizing chip V4 # Pins, 15 # Pins, 16 # The pins are connected together and then connected with the output end of the-12V power supply of the first voltage conversion circuit, one end of the capacitor C65 is connected with 13 of the second linear voltage stabilizing chip V4 # The other end of the pin and the capacitor C65 is grounded, and one end of the capacitor C66 is connected with 13 of the second linear voltage stabilizing chip V4 # The other end of the pin and the capacitor C66 is grounded, and one of the parallel common terminals after the capacitor C67 and the capacitor C68 are connected in parallel is connected with 14 of the second linear voltage stabilizing chip V4 # The pin and the other parallel common ground are grounded, and two ends of the capacitor C64 are respectively connected with 20 of the second linear voltage stabilizing chip V4 # Pin and 3 # The pin is connected, after the resistor R32 is connected in series with the resistor R33, the non-series end of the resistor R32 is connected with 20 of the second linear voltage stabilizing chip V4 # Pin connection, non-series connection end of resistor R33 and 7 of second linear voltage stabilizing chip V4 # Pin and 21 # Pin connection, resistor R32 and resistor R33 are connected in series and commonly connected with 3 of second linear voltage stabilizing chip V4 # Pin, one of the parallel common terminals of capacitor C62 and capacitor C63 is connected in parallel with 20 of the second linear voltage stabilizing chip V4 # Pin, another parallel common ground, 20 of the second linear voltage stabilizing chip V4 # Pin and 1 # Pins are connected together, 20 of the second linear voltage stabilizing chip V4 # The pin is used as the-5V power supply output end of the second linear voltage stabilizing chip V4.
Further, the model of the second linear voltage stabilizing chip V4 is TPS7a3301.
The utility model has the advantages that:
(1) The constant current source circuit outputs exciting current by adopting the first operational amplifier U8, and the exciting current output by adopting the second operational amplifier U9 is collected in real time for feedback adjustment, so that the stability and reliability of the output exciting current are ensured;
(2) The first operational amplifier U8 adopts an operational amplifier with a high common mode rejection ratio, so that the anti-interference performance of low-temperature measurement is improved, and the precision is higher;
(3) The power supply circuit adopts the chopper type 220-12/AC-DC module, and the FC-LX1D filter is arranged in front of the chopper type 220-12/AC-DC module, so that the noise of the power supply circuit is reduced, and the power supply circuit is suitable for occasions sensitive to the noise.
Drawings
FIG. 1 is a schematic diagram of a carbon resistance temperature sensor constant current source circuit for cryogenic measurement according to an embodiment of the utility model;
FIG. 2 is a schematic diagram of a first voltage conversion circuit of a carbon resistance temperature sensor constant current source circuit for cryogenic measurement according to an embodiment of the utility model;
FIG. 3 is a schematic diagram of a second voltage conversion circuit of a carbon resistance temperature sensor constant current source circuit for cryogenic measurement according to an embodiment of the utility model;
fig. 4 is a schematic diagram of a third voltage conversion circuit of a carbon resistance temperature sensor constant current source circuit for low temperature measurement according to an embodiment of the present utility model.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions in the embodiments of the present utility model will be clearly and completely described in the following in conjunction with the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
The technical scheme of the utility model is further described below with reference to the attached drawings and specific embodiments:
example 1
As shown in fig. 1, the constant current source circuit of the carbon resistance temperature sensor for low temperature measurement of the present embodiment includes: the first operational amplifier U8, the second operational amplifier U9, the capacitor C123, the capacitor C124 and the resistor R23; 1 of the first operational amplifier U8 # The pins are grounded, the first4 of an operational amplifier U8 # Pin is connected with reference voltage VDD_R, 8 of first operational amplifier U8 # The pin is connected with a +5V power supply, 5 of the first operational amplifier U8 # The pin is connected with a-5V power supply, one end of a capacitor C123 is connected with 8 of a first operational amplifier U8 # The other end of the capacitor C123 is grounded, and one end of the capacitor C124 is connected with 5 of the first operational amplifier U8 # Pin is connected, the other end of the capacitor C124 is grounded, 7 of the first operational amplifier U8 # The pin is connected with one end of a resistor R23, and the other end of the resistor R23 is connected with 3 of a second operational amplifier U9 # Pin connection, 4 of second operational amplifier U9 # The pin is connected with a-5V power supply, 7 of a second operational amplifier U9 # Pin is connected with +5V power supply, 6 of second operational amplifier U9 # Pin 6 with first op amp U8 # Pin connection, 2 of second operational amplifier U9 # Pin 6 with second operational amplifier U9 # The pins are connected; resistor R23 and 3 of second operational amplifier U9 # The common point of connection of the pins is used as the output end of the constant current source circuit.
The model of the first operational amplifier U8 is AD8221, the AD8221 is a programmable high-performance instrument amplifier with excellent common mode rejection performance, a sensor interface circuit is formed by an operational amplifier with high common mode rejection ratio, and the anti-interference performance of a low-temperature measurement system can be improved when the high-precision temperature measurement circuit is designed; the AD8221 has the advantages of low noise, programmable gain setting and the like, and is very suitable for the fields with higher requirements on direct current characteristics, such as bridge circuit signal measurement and the like.
The model of the second operational amplifier U9 is AD8638, the AD8638 is a wide bandwidth and automatic zero setting amplifier, and the second operational amplifier has low offset voltage, low offset drift, low noise, low cost and high precision.
Working principle of constant current source circuit:
for example, the input reference voltage vdd_r is 2.5V, the output end of the first operational amplifier U8 obtains a voltage of 2.5V, the resistance value of the designed R23 is 250kΩ, and then the output of the constant current source circuit is 10 μa, so that the constant current source circuit provides a stable excitation of 10 μa for the carbon resistance temperature sensor; the second operational amplifier U9 is used for collecting the output value of the constant current source circuit in real time, and sending the output value of the constant current source circuit into the first operational amplifier U8 for feedback adjustment, so that the output value of the constant current source circuit is stabilized at 10 mu A.
As shown in fig. 2 to 4, a power supply circuit for a constant current source circuit includes: the first voltage conversion circuit is used for converting 220V alternating current input into +/-12V direct current, the second voltage conversion circuit is used for converting +12V direct current into +5V direct current, and the third voltage conversion circuit is used for converting-12V direct current into-5V direct current.
As shown in fig. 2, a schematic circuit diagram of the first voltage conversion circuit includes: step-down chopper module V1, filter V2, fuse F1, electrolytic capacitor CE2, capacitor C54, capacitor C55, zener diode TVS9, zener diode TVS10; the step-down chopper module V1 adopts a chopper type 220-12/AC-DC module, the filter V2 adopts an FC-LX1D filter, and the FC-LX1D filter is suitable for occasions sensitive to noise.
3 of the filter V2 # Pin is connected with the live wire of 220V alternating current power supply, 2 of filter V2 # The pin is connected with the zero line of 220V alternating current power supply, 1 of the filter V2 # Pin is grounded, 4 of the filter V2 # Pin and 3 of step-down chopper module V1 # Pin connection, 5 of filter V2 # Pin and step-down chopper module V1 2 # Pin connection, 1 of filter V2 # The pin is grounded, and the cathode of the electrolytic capacitor CE1 is connected with 4 of the buck chopper module V1 # Pin, positive electrode of electrolytic capacitor CE1 is connected with 6 of step-down chopper module V1 # Pin, cathode of electrolytic capacitor CE2 is connected with 6 of step-down chopper module V1 # Pin, positive electrode of electrolytic capacitor CE2 is connected with 8 of step-down chopper module V1 # Pin, two ends of capacitor C54 are respectively connected with 4 of step-down chopper module V1 # 6 of pin and step-down chopper module V1 # Pin, two ends of capacitor C55 are respectively connected with 6 of step-down chopper module V1 # Pin and step-down chopper V1 8 # Pin, step-down chopper module V1 6 # Pin is grounded, one end of the voltage stabilizing diode TVS94 with step-down chopper module V1 # The other end of the voltage stabilizing diode TVS9 is grounded, and one end of the voltage stabilizing diode TVS10 is connected with 8 of the step-down chopper module V1 # The other end of the voltage stabilizing diode TVS10 is grounded, and the pin is connected with 8 of the step-down chopper module V1 # The pin is used as the output end of the +12V power supply and is connected with the input end of the second voltage conversion circuit, and the 4 of the buck chopper module V1 # The pin is used as the output end of the-12V power supply and is connected with the input end of the third voltage conversion circuit. The external 220V alternating current is connected to the FC-LX1D filter through the fuse, and is connected to the step-down chopper module V1 after being filtered, so that the 220V alternating current is converted into +/-12V power supply and output.
As shown in fig. 3, a schematic circuit diagram of the second voltage conversion circuit includes: the first linear voltage stabilizing chip V3, the capacitor C56, the capacitor C57, the capacitor C58, the capacitor C59, the capacitor C60, the capacitor C61, the resistor R30 and the resistor R31; the model of the first linear voltage stabilizing chip V3 is TPS7A4701, TPS7A4701 is an ultra-low noise (4 mu V RMS) LDO, can provide a 1A load and a positive output voltage, and an external feedback resistor configures the output voltage of TPS7A4701.
13 of the first linear voltage stabilizing chip V3 # Pins, 15 # Pins, 16 # The pins are connected together and then connected with the output end of the +12V power supply of the first voltage conversion circuit, one end of the capacitor C58 is connected with 13 of the first linear voltage stabilizing chip V3 # The other end of the pin and the capacitor C58 is grounded, and one end of the capacitor C59 is connected with 13 of the first linear voltage stabilizing chip V3 # The other end of the pin and the capacitor C59 is grounded, one end of the capacitor C60 and one end of the capacitor C61 are connected together and then connected with 14 of the first linear voltage stabilizing chip V3 # The other ends of the pin, the capacitor C60 and the capacitor C61 are grounded, and after the resistor R30 and the resistor R31 are connected in series, the non-series end of the resistor R30 and 1 of the first linear voltage stabilizing chip V3 # Pin connection, non-series grounding of the resistor R31, and 3 of the first linear voltage stabilizing chip V3 connected with the series common point of the resistor R30 and the resistor R31 # Pin, one of the parallel common terminals of the capacitor C56 and the capacitor C57 is connected in parallel with 1 of the first linear voltage stabilizing chip V3 # The pin and the other parallel common ground are grounded, the first1 of a Linear Voltage-stabilizing chip V3 # Pins and 20 # Pins are connected together, 6 of the first linear voltage stabilizing chip V3 # Pins, 7 # Pin and 10 # Pin grounding, 1 of first linear voltage stabilizing chip V3 # The pin is used as the +5V power supply output end of the first linear voltage stabilizing chip V3.
As shown in fig. 4, a schematic circuit diagram of a third voltage conversion circuit includes: the second linear voltage stabilizing chip V4, a capacitor C62, a capacitor C63, a capacitor C64, a capacitor C65, a capacitor C66, a capacitor C67, a capacitor C68, a resistor R32 and a resistor R33; the second linear voltage stabilizing chip V4 is in the type of TPS7A3301, and the TPS7A3301 linear voltage stabilizer is an ultra-low noise (16 mu VRMS,72 dPSRR) linear voltage stabilizer supporting the maximum input voltage of 36V and can supply power for the highest 1A load.
13 of the second linear voltage stabilizing chip V4 # Pins, 15 # Pins, 16 # The pins are connected together and then connected with the output end of the-12V power supply of the first voltage conversion circuit, one end of the capacitor C65 is connected with 13 of the second linear voltage stabilizing chip V4 # The other end of the pin and the capacitor C65 is grounded, and one end of the capacitor C66 is connected with 13 of the second linear voltage stabilizing chip V4 # The other end of the pin and the capacitor C66 is grounded, and one of the parallel common terminals after the capacitor C67 and the capacitor C68 are connected in parallel is connected with 14 of the second linear voltage stabilizing chip V4 # The pin and the other parallel common ground are grounded, and two ends of the capacitor C64 are respectively connected with 20 of the second linear voltage stabilizing chip V4 # Pin and 3 # The pin is connected, after the resistor R32 is connected in series with the resistor R33, the non-series end of the resistor R32 is connected with 20 of the second linear voltage stabilizing chip V4 # Pin connection, non-series connection end of resistor R33 and 7 of second linear voltage stabilizing chip V4 # Pin and 21 # Pin connection, resistor R32 and resistor R33 are connected in series and commonly connected with 3 of second linear voltage stabilizing chip V4 # Pin, one of the parallel common terminals of capacitor C62 and capacitor C63 is connected in parallel with 20 of the second linear voltage stabilizing chip V4 # Pin, another parallel common ground, 20 of the second linear voltage stabilizing chip V4 # Pin and 1 # Pins are connected together, 20 of the second linear voltage stabilizing chip V4 # Pin as second linear voltage stabilizing chipV4-5V power supply output end.
The above embodiments are only for illustrating the technical solution of the present utility model, and are not limiting; although the utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present utility model.
Claims (9)
1. A carbon resistance temperature sensor constant current source circuit for low temperature measurement, comprising: the first operational amplifier U8, the second operational amplifier U9, the capacitor C123, the capacitor C124, the resistor R23 and the power supply circuit; 1 of the first operational amplifier U8 # Pin is grounded, 4 of the first operational amplifier U8 # Pin is connected with reference voltage, 8 of first operational amplifier U8 # Pin and 5 of first operational amplifier U8 # Pins are connected with a power supply circuit, one end of a capacitor C123 is connected with 8 of a first operational amplifier U8 # The other end of the capacitor C123 is grounded, and one end of the capacitor C124 is connected with 5 of the first operational amplifier U8 # Pin is connected, the other end of the capacitor C124 is grounded, 7 of the first operational amplifier U8 # The pin is connected with one end of a resistor R23, and the other end of the resistor R23 is connected with 3 of a second operational amplifier U9 # Pin connection, 4 of second operational amplifier U9 # Pin and 7 of second operational amplifier U9 # Pins are connected with a power supply circuit, 6 of a second operational amplifier U9 # Pin 6 with first op amp U8 # Pin connection, 2 of second operational amplifier U9 # Pin 6 with second operational amplifier U9 # The pins are connected; resistor R23 and 3 of second operational amplifier U9 # The common point of connection of the pins is used as the output end of the constant current source circuit.
2. The constant current source circuit according to claim 1, wherein the first operational amplifier U8 has a model AD8221 and the second operational amplifier U9 has a model AD8638.
3. The constant current source circuit according to claim 1, wherein the power supply circuit includes: a first voltage conversion circuit, a second voltage conversion circuit, a third voltage conversion circuit; the input end of the first voltage conversion circuit is connected with a 220V alternating current power supply, and the output end of the first voltage conversion circuit is respectively connected with the second voltage conversion circuit and the third voltage conversion circuit; 8 of the first operational amplifier U8 # The pin is connected with the output end of the second voltage conversion circuit, 5 of the first operational amplifier U8 # The pin is connected with the output end of the third voltage conversion circuit; 7 of the second operational amplifier U9 # The pin is connected with the output end of the second voltage conversion circuit and 4 of the second operational amplifier U9 # The pin is connected with the output end of the third voltage conversion circuit.
4. The constant current source circuit according to claim 3, wherein the first voltage conversion circuit includes: step-down chopper module V1, filter V2, fuse F1, electrolytic capacitor CE2, capacitor C54, capacitor C55, zener diode TVS9, zener diode TVS10; 3 of the filter V2 # Pin is connected with the live wire of 220V alternating current power supply, 2 of filter V2 # The pin is connected with the zero line of 220V alternating current power supply, 1 of the filter V2 # Pin is grounded, 4 of the filter V2 # Pin and 3 of step-down chopper module V1 # Pin connection, 5 of filter V2 # Pin and step-down chopper module V1 2 # Pin connection, 1 of filter V2 # The pin is grounded, and the cathode of the electrolytic capacitor CE1 is connected with 4 of the buck chopper module V1 # Pin, positive electrode of electrolytic capacitor CE1 is connected with 6 of step-down chopper module V1 # Pin, cathode of electrolytic capacitor CE2 is connected with 6 of step-down chopper module V1 # Pin, positive electrode of electrolytic capacitor CE2 is connected with 8 of step-down chopper module V1 # Pin, two ends of capacitor C54 are respectively connected with 4 of step-down chopper module V1 # 6 of pin and step-down chopper module V1 # Pin, two ends of capacitor C55 are respectively connected with 6 of step-down chopper module V1 # Pin and step-down chopper V1 8 # Pin, step-down chopper module V1 6 # The pin is grounded, one end of the voltage stabilizing diode TVS9 and 4 of the step-down chopper module V1 # The other end of the voltage stabilizing diode TVS9 is grounded, and one end of the voltage stabilizing diode TVS10 is connected with 8 of the step-down chopper module V1 # The other end of the voltage stabilizing diode TVS10 is grounded, and the pin is connected with 8 of the step-down chopper module V1 # The pin is used as the output end of the +12V power supply and is connected with the input end of the second voltage conversion circuit, and the 4 of the buck chopper module V1 # The pin is used as the output end of the-12V power supply and is connected with the input end of the third voltage conversion circuit.
5. The constant current source circuit according to claim 4, wherein the step-down chopper module V1 is a chopper 220-12/AC-DC module, and the filter V2 is an FC-LX1D filter.
6. The constant current source circuit according to claim 4, wherein the second voltage conversion circuit includes: the first linear voltage stabilizing chip V3, the capacitor C56, the capacitor C57, the capacitor C58, the capacitor C59, the capacitor C60, the capacitor C61, the resistor R30 and the resistor R31; 13 of the first linear voltage stabilizing chip V3 # Pins, 15 # Pins, 16 # The pins are connected together and then connected with the output end of the +12V power supply of the first voltage conversion circuit, one end of the capacitor C58 is connected with 13 of the first linear voltage stabilizing chip V3 # The other end of the pin and the capacitor C58 is grounded, and one end of the capacitor C59 is connected with 13 of the first linear voltage stabilizing chip V3 # The other end of the pin and the capacitor C59 is grounded, one end of the capacitor C60 and one end of the capacitor C61 are connected together and then connected with 14 of the first linear voltage stabilizing chip V3 # The other ends of the pin, the capacitor C60 and the capacitor C61 are grounded, and after the resistor R30 and the resistor R31 are connected in series, the non-series end of the resistor R30 and 1 of the first linear voltage stabilizing chip V3 # Pin connection, non-series grounding of the resistor R31, and 3 of the first linear voltage stabilizing chip V3 connected with the series common point of the resistor R30 and the resistor R31 # Pin, one of the parallel common terminals of the capacitor C56 and the capacitor C57 is connected in parallel with 1 of the first linear voltage stabilizing chip V3 # Pin, anotherA common ground connected in parallel, 1 of the first linear voltage stabilizing chip V3 # Pins and 20 # Pins are connected together, 6 of the first linear voltage stabilizing chip V3 # Pins, 7 # Pin and 10 # Pin grounding, 1 of first linear voltage stabilizing chip V3 # The pin is used as the +5V power supply output end of the first linear voltage stabilizing chip V3.
7. The constant current source circuit according to claim 6, wherein the first linear voltage regulator chip V3 has a type TPS7a4701.
8. The constant current source circuit according to claim 4, wherein the third voltage conversion circuit includes: the second linear voltage stabilizing chip V4, a capacitor C62, a capacitor C63, a capacitor C64, a capacitor C65, a capacitor C66, a capacitor C67, a capacitor C68, a resistor R32 and a resistor R33; 13 of the second linear voltage stabilizing chip V4 # Pins, 15 # Pins, 16 # The pins are connected together and then connected with the output end of the-12V power supply of the first voltage conversion circuit, one end of the capacitor C65 is connected with 13 of the second linear voltage stabilizing chip V4 # The other end of the pin and the capacitor C65 is grounded, and one end of the capacitor C66 is connected with 13 of the second linear voltage stabilizing chip V4 # The other end of the pin and the capacitor C66 is grounded, and one of the parallel common terminals after the capacitor C67 and the capacitor C68 are connected in parallel is connected with 14 of the second linear voltage stabilizing chip V4 # The pin and the other parallel common ground are grounded, and two ends of the capacitor C64 are respectively connected with 20 of the second linear voltage stabilizing chip V4 # Pin and 3 # The pin is connected, after the resistor R32 is connected in series with the resistor R33, the non-series end of the resistor R32 is connected with 20 of the second linear voltage stabilizing chip V4 # Pin connection, non-series connection end of resistor R33 and 7 of second linear voltage stabilizing chip V4 # Pin and 21 # Pin connection, resistor R32 and resistor R33 are connected in series and commonly connected with 3 of second linear voltage stabilizing chip V4 # Pin, one of the parallel common terminals of capacitor C62 and capacitor C63 is connected in parallel with 20 of the second linear voltage stabilizing chip V4 # Pin, another parallel common ground, 20 of the second linear voltage stabilizing chip V4 # Pin and 1 # Pins are connected together20 of the second Linear Voltage-stabilizing chip V4 # The pin is used as the-5V power supply output end of the second linear voltage stabilizing chip V4.
9. The constant current source circuit according to claim 8, wherein the second linear voltage regulator chip V4 has a type TPS7a3301.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321450914.9U CN220105580U (en) | 2023-06-07 | 2023-06-07 | Constant current source circuit of carbon resistance temperature sensor for low-temperature measurement |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321450914.9U CN220105580U (en) | 2023-06-07 | 2023-06-07 | Constant current source circuit of carbon resistance temperature sensor for low-temperature measurement |
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| CN220105580U true CN220105580U (en) | 2023-11-28 |
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