CN220105580U - A carbon resistance temperature sensor constant current source circuit for low temperature measurement - Google Patents

A carbon resistance temperature sensor constant current source circuit for low temperature measurement Download PDF

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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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capacitor
operational amplifier
resistor
voltage stabilizing
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王铭翔
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Hefei Institute Of Technology Innovation Engineering
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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

一种用于低温测量的碳电阻温度传感器恒流源电路A carbon resistance temperature sensor constant current source circuit for low temperature measurement

技术领域Technical field

本实用新型属于接触式低温测量技术领域,涉及一种用于低温测量的碳电阻温度传感器恒流源电路。The utility model belongs to the technical field of contact low-temperature measurement and relates to a carbon resistance temperature sensor constant current source circuit used for low-temperature measurement.

背景技术Background technique

碳电阻温度传感器由于其具有极高的灵敏度,常被用于测量液氦的温度(5至80K)。碳电阻温度传感器需要外加电源才能被驱动工作。由于碳电阻温度传感器,在低温时,其自身阻值达几千欧,当电流越大,其自身发热功率将很高,将产生焦耳热,当焦耳热过大时会带来较大的测量误差,严重情况下甚至会引起测量错误,所以碳电阻温度传感器需要采用小电流驱动。因此需要设计一种稳定可靠的恒流源来限制碳电阻温度传感器产生的焦耳热。Carbon resistance temperature sensors are often used to measure the temperature of liquid helium (5 to 80K) due to their extremely high sensitivity. Carbon resistance temperature sensors require an external power source to be driven. Because the carbon resistance temperature sensor has a resistance of several thousand ohms at low temperatures, when the current is larger, its own heating power will be very high and Joule heat will be generated. When Joule heat is too large, it will cause larger measurement errors. Errors may even cause measurement errors in severe cases, so the carbon resistance temperature sensor needs to be driven by a small current. Therefore, it is necessary to design a stable and reliable constant current source to limit the Joule heat generated by the carbon resistance temperature sensor.

实用新型内容Utility model content

本实用新型的目的如何设计一种稳定可靠的恒流源,以解决因碳电阻温度传感器产生的焦耳热而导致的低温测量不准确的问题。The purpose of this utility model is how to design a stable and reliable constant current source to solve the problem of inaccurate low temperature measurement caused by the Joule heat generated by the carbon resistance temperature sensor.

本实用新型是通过以下技术方案解决上述技术问题的:The utility model solves the above technical problems through the following technical solutions:

一种用于低温测量的碳电阻温度传感器恒流源电路,包括:第一运算放大器U8、第二运算放大器U9、电容C123、电容C124、电阻R23、供电电路;所述第一运算放大器U8的1#引脚接地,第一运算放大器U8的4#引脚接参考电压,第一运算放大器U8的8#引脚及第一运算放大器U8的5#引脚均接供电电路,电容C123的一端与第一运算放大器U8的8#引脚连接,电容C123的另一端接地,电容C124的一端与第一运算放大器U8的5#引脚连接,电容C124的另一端接地,第一运算放大器U8的7#引脚与电阻R23的一端连接,电阻R23的另一端与第二运算放大器U9的3#引脚连接,第二运算放大器U9的4#引脚及第二运算放大器U9的7#引脚均接供电电路,第二运算放大器U9的6#引脚与第一运算放大器U8的6#引脚连接,第二运算放大器U9的2#引脚与第二运算放大器U9的6#引脚连接;电阻R23与第二运算放大器U9的3#引脚的连接公共点作为恒流源电路的输出端。A carbon resistance temperature sensor constant current source circuit for low temperature measurement, including: a first operational amplifier U8, a second operational amplifier U9, a capacitor C123, a capacitor C124, a resistor R23, and a power supply circuit; the first operational amplifier U8 The 1 # pin is connected to ground, the 4 # pin of the first operational amplifier U8 is connected to the reference voltage, the 8 # pin of the first operational amplifier U8 and the 5 # pin of the first operational amplifier U8 are both connected to the power supply circuit, and one end of the capacitor C123 Connect to the 8 # pin of the first operational amplifier U8, the other end of the capacitor C123 is connected to the ground, one end of the capacitor C124 is connected to the 5 # pin of the first operational amplifier U8, the other end of the capacitor C124 is connected to the ground, the first operational amplifier U8 The 7 # pin is connected to one end of the resistor R23, the other end of the resistor R23 is connected to the 3 # pin of the second operational amplifier U9, the 4 # pin of the second operational amplifier U9 and the 7 # pin of the second operational amplifier U9 Both are connected to the power supply circuit, the 6 # pin of the second operational amplifier U9 is connected to the 6 # pin of the first operational amplifier U8, the 2 # pin of the second operational amplifier U9 is connected to the 6 # pin of the second operational amplifier U9 ; The common connection point between the resistor R23 and the 3 # pin of the second operational amplifier U9 is used as the output end of the constant current source circuit.

进一步地,所述第一运算放大器U8的型号为AD8221,所述第二运算放大器U9的型号为AD8638。Further, the model of the first operational amplifier U8 is AD8221, and the model of the second operational amplifier U9 is AD8638.

进一步地,所述供电电路包括:第一电压转换电路、第二电压转换电路、第三电压转换电路;所述第一电压转换电路的输入端接220V交流电源,第一电压转换电路的输出端分别接第二电压转换电路和第三电压转换电路;所述第一运算放大器U8的8#引脚接第二电压转换电路的输出端,第一运算放大器U8的5#引脚接第三电压转换电路的输出端;所述第二运算放大器U9的7#引脚接第二电压转换电路的输出端、第二运算放大器U9的4#引脚接第三电压转换电路的输出端。Further, the power supply circuit includes: a first voltage conversion circuit, a second voltage conversion circuit, and a third voltage conversion circuit; the input terminal of the first voltage conversion circuit is connected to the 220V AC power supply, and the output terminal of the first voltage conversion circuit is connected to the 220V AC power supply. Connect the second voltage conversion circuit and the third voltage conversion circuit respectively; the 8 # pin of the first operational amplifier U8 is connected to the output end of the second voltage conversion circuit, and the 5 # pin of the first operational amplifier U8 is connected to the third voltage The output end of the conversion circuit; the 7 # pin of the second operational amplifier U9 is connected to the output end of the second voltage conversion circuit, and the 4 # pin of the second operational amplifier U9 is connected to the output end of the third voltage conversion circuit.

进一步地,所述第一电压转换电路包括:降压斩波模块V1、滤波器V2、保险丝F1、电解电容CE1、电解电容CE2、电容C54、电容C55、稳压二极管TVS9、稳压二极管TVS10;所述滤波器V2的3#引脚接220V交流电源的火线,滤波器V2的2#引脚接220V交流电源的零线,滤波器V2的1#引脚接地,滤波器V2的4#引脚与降压斩波模块V1的3#引脚连接,滤波器V2的5#引脚与降压斩波模块V1的2#引脚连接,滤波器V2的1#引脚接地,电解电容CE1的负极接降压斩波模块V1的4#引脚,电解电容CE1的正极接降压斩波模块V1的6#引脚,电解电容CE2的负极接降压斩波模块V1的6#引脚,电解电容CE2的正极接降压斩波模块V1的8#引脚,电容C54的两端分别与降压斩波模块V1的4#引脚与降压斩波模块V1的6#引脚,电容C55的两端分别与降压斩波模块V1的6#引脚与降压斩波模块V1的8#引脚,降压斩波模块V1的6#引脚接地,稳压二极管TVS9的一端与降压斩波模块V1的4#引脚连接,稳压二极管TVS9的另一端接地,稳压二极管TVS10的一端与降压斩波模块V1的8#引脚连接,稳压二极管TVS10的另一端接地,降压斩波模块V1的8#引脚作为+12V电源的输出端与第二电压转换电路的输入端连接,降压斩波模块V1的4#引脚作为-12V电源的输出端与第三电压转换电路的输入端连接。Further, the first voltage conversion circuit includes: step-down chopper module V1, filter V2, fuse F1, electrolytic capacitor CE1, electrolytic capacitor CE2, capacitor C54, capacitor C55, voltage stabilizing diode TVS9, voltage stabilizing diode TVS10; The 3 # pin of the filter V2 is connected to the live wire of the 220V AC power supply, the 2 # pin of the filter V2 is connected to the neutral wire of the 220V AC power supply, the 1 # pin of the filter V2 is connected to ground, and the 4 # pin of the filter V2 is connected to the ground. The pin is connected to the 3 # pin of the step-down chopper module V1, the 5 # pin of the filter V2 is connected to the 2 # pin of the step-down chopper module V1, the 1 # pin of the filter V2 is connected to the ground, and the electrolytic capacitor CE1 The negative pole of the electrolytic capacitor CE1 is connected to the 4 # pin of the step-down chopper module V1, the positive pole of the electrolytic capacitor CE1 is connected to the 6 # pin of the step-down chopper module V1, and the negative pole of the electrolytic capacitor CE2 is connected to the 6 # pin of the step-down chopper module V1. , the positive electrode of the electrolytic capacitor CE2 is connected to the 8 # pin of the step-down chopper module V1, and the two ends of the capacitor C54 are connected to the 4 # pin of the step-down chopper module V1 and the 6 # pin of the step-down chopper module V1 respectively. The two ends of the capacitor C55 are connected to the 6 # pin of the step-down chopper module V1 and the 8 # pin of the step-down chopper module V1 respectively. The 6 # pin of the step-down chopper module V1 is connected to ground, and one end of the zener diode TVS9 Connect to the 4 # pin of the step-down chopper module V1, the other end of the zener diode TVS9 is connected to ground, one end of the zener diode TVS10 is connected to the 8 # pin of the step-down chopper module V1, and the other end of the zener diode TVS10 Grounded, the 8 # pin of the step-down chopper module V1 serves as the output end of the +12V power supply and is connected to the input end of the second voltage conversion circuit, and the 4 # pin of the step-down chopper module V1 serves as the output end of the -12V power supply and is connected to the ground. The input terminal of the third voltage conversion circuit is connected.

进一步地,所述降压斩波模块V1采用斩波式220-12/AC-DC模块,所述滤波器V2采用FC-LX1D滤波器。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.

进一步地,所述第二电压转换电路包括:第一线性稳压芯片V3、电容C56、电容C57、电容C58、电容C59、电容C60、电容C61,电阻R30、电阻R31;所述第一线性稳压芯片V3的13#引脚、15#引脚、16#引脚连接在一起后再接第一电压转换电路的+12V电源的输出端,电容C58的一端接第一线性稳压芯片V3的13#引脚、电容C58的另一端接地,电容C59的一端接第一线性稳压芯片V3的13#引脚、电容C59的另一端接地,电容C60与电容C61的一端连接在一起后再接第一线性稳压芯片V3的14#引脚、电容C60与电容C61的另一端均接地,电阻R30与电阻R31串联后电阻R30的非串联端与第一线性稳压芯片V3的1#引脚连接、电阻R31的非串联端接地、电阻R30与电阻R31串联公共点接第一线性稳压芯片V3的3#引脚,电容C56与电容C57并联后的其中一个并联公共端接第一线性稳压芯片V3的1#引脚、另一个并联公共端接地,第一线性稳压芯片V3的1#引脚与20#引脚连接在一起,第一线性稳压芯片V3的6#引脚、7#引脚和10#引脚接地,第一线性稳压芯片V3的1#引脚作为第一线性稳压芯片V3的+5V电源输出端。Further, the second voltage conversion circuit includes: a first linear voltage stabilizing chip V3, a capacitor C56, a capacitor C57, a capacitor C58, a capacitor C59, a capacitor C60, a capacitor C61, a resistor R30 and a resistor R31; Pins 13 # , 15 # , and 16 # of the pressure chip V3 are connected together and then connected to the output end of the +12V power supply of the first voltage conversion circuit. One end of the capacitor C58 is connected to the first linear voltage regulator chip V3. The 13 # pin and the other end of the capacitor C58 are connected to the ground. One end of the capacitor C59 is connected to the 13 # pin of the first linear voltage regulator chip V3. The other end of the capacitor C59 is connected to the ground. One end of the capacitor C60 and the capacitor C61 are connected together and then connected. The 14 # pin of the first linear voltage stabilizing chip V3, the other ends of the capacitor C60 and the capacitor C61 are all connected to ground. After the resistor R30 and the resistor R31 are connected in series, the non-series end of the resistor R30 is connected to the 1 # pin of the first linear voltage stabilizing chip V3. Connection, the non-series end of resistor R31 is grounded, the common point of resistor R30 and resistor R31 in series is connected to the # 3 pin of the first linear regulator chip V3, and one of the parallel common terminals of capacitor C56 and capacitor C57 connected in parallel is connected to the first linear regulator chip. The 1 # pin of the pressure chip V3 and the other parallel common terminal are connected to the ground. The 1 # pin and the 20 # pin of the first linear voltage regulator chip V3 are connected together. The 6 # pin of the first linear voltage regulator chip V3, The 7 # pin and the 10 # pin are grounded, and the 1 # pin of the first linear voltage stabilizing chip V3 serves as the +5V power output terminal of the first linear voltage stabilizing chip V3.

进一步地,所述第一线性稳压芯片V3的型号为TPS7A4701。Further, the model of the first linear voltage regulator chip V3 is TPS7A4701.

进一步地,所述第三电压转换电路包括:第二线性稳压芯片V4、电容C62、电容C63、电容C64、电容C65、电容C66、电容C67、电容C68,电阻R32、电阻R33;所述第二线性稳压芯片V4的13#引脚、15#引脚、16#引脚连接在一起后再接第一电压转换电路的-12V电源的输出端,电容C65的一端接第二线性稳压芯片V4的13#引脚、电容C65的另一端接地,电容C66的一端接第二线性稳压芯片V4的13#引脚、电容C66的另一端接地,电容C67与电容C68并联后的其中一个并联公共端接第二线性稳压芯片V4的14#引脚、另一个并联公共端接地,电容C64的两端分别与第二线性稳压芯片V4的20#引脚以及3#引脚连接,电阻R32与电阻R33串联后电阻R32的非串联端与第二线性稳压芯片V4的20#引脚连接、电阻R33的非串联端与第二线性稳压芯片V4的7#引脚以及21#引脚连接、电阻R32与电阻R33串联公共点接第二线性稳压芯片V4的3#引脚,电容C62与电容C63并联后的其中一个并联公共端接第二线性稳压芯片V4的20#引脚、另一个并联公共端接地,第二线性稳压芯片V4的20#引脚与1#引脚连接在一起,第二线性稳压芯片V4的20#引脚作为第二线性稳压芯片V4的-5V电源输出端。Further, the third voltage conversion circuit includes: a 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 13 # pin, 15 # pin, and 16 # pin of the two linear voltage regulator chips V4 are connected together and then connected to the output end of the -12V power supply of the first voltage conversion circuit. One end of the capacitor C65 is connected to the second linear voltage regulator The 13 # pin of the chip V4 and the other end of the capacitor C65 are connected to the ground. One end of the capacitor C66 is connected to the 13 # pin of the second linear voltage regulator chip V4. The other end of the capacitor C66 is connected to the ground. One of the capacitor C67 and the capacitor C68 is connected in parallel. The parallel common terminal is connected to the 14 # pin of the second linear voltage regulator chip V4, and the other parallel common terminal is connected to ground. The two ends of the capacitor C64 are connected to the 20 # pin and 3 # pin of the second linear voltage regulator chip V4 respectively. After the resistor R32 and the resistor R33 are connected in series, the non-series end of the resistor R32 is connected to the 20 # pin of the second linear voltage stabilizing chip V4, and the non-series connection end of the resistor R33 is connected to the 7 # pin and 21 # of the second linear voltage stabilizing chip V4. Pin connection, the common point of resistor R32 and resistor R33 in series is connected to pin 3 of the second linear voltage regulator chip V4, and one of the parallel common terminals of capacitor C62 and capacitor C63 connected in parallel is connected to pin 20 of the second linear voltage regulator chip V4. pin, the other parallel common terminal is grounded, the 20 # pin of the second linear voltage stabilizing chip V4 is connected to the 1 # pin, and the 20 # pin of the second linear voltage stabilizing chip V4 is used as the second linear voltage stabilizing chip -5V power output of V4.

进一步地,所述第二线性稳压芯片V4的型号为TPS7A3301。Further, the model of the second linear voltage regulator chip V4 is TPS7A3301.

本实用新型的优点在于:The advantages of this utility model are:

(1)本实用新型的恒流源电路输采用第一运算放大器U8输出激励电流,采用第二运算放大器U9实时采集输出的激励电流进行反馈调节,保证了输出的激励电流的稳定可靠;(1) The constant current source circuit of the present invention uses the first operational amplifier U8 to output the excitation current, and uses the second operational amplifier U9 to collect the output excitation current in real time for feedback adjustment, ensuring the stability and reliability of the output excitation current;

(2)第一运算放大器U8采用高共模抑制比的运放,提高了低温测量的抗干扰性能,精度更高;(2) The first operational amplifier U8 uses an operational amplifier with a high common-mode rejection ratio, which improves the anti-interference performance of low-temperature measurements and results in higher accuracy;

(3)供电电路采用斩波式220-12/AC-DC模块,并在斩波式220-12/AC-DC模块前设置FC-LX1D滤波器,减小了供电电路的噪声,适用于对噪声比较敏感的场合。(3) The power supply circuit adopts the chopper-type 220-12/AC-DC module, and sets the FC-LX1D filter in front of the chopper-type 220-12/AC-DC module, which reduces the noise of the power supply circuit and is suitable for Noise sensitive situations.

附图说明Description of the drawings

图1是本实用新型实施例的用于低温测量的碳电阻温度传感器恒流源电路的原理图;Figure 1 is a schematic diagram of a carbon resistance temperature sensor constant current source circuit for low temperature measurement according to an embodiment of the present invention;

图2是本实用新型实施例的用于低温测量的碳电阻温度传感器恒流源电路的第一电压转换电路的原理图;Figure 2 is a schematic diagram of the first voltage conversion circuit of the constant current source circuit of the carbon resistance temperature sensor used for low-temperature measurement according to the embodiment of the present invention;

图3是本实用新型实施例的用于低温测量的碳电阻温度传感器恒流源电路的第二电压转换电路的原理图;Figure 3 is a schematic diagram of the second voltage conversion circuit of the carbon resistance temperature sensor constant current source circuit used for low-temperature measurement according to the embodiment of the present invention;

图4是本实用新型实施例的用于低温测量的碳电阻温度传感器恒流源电路的第三电压转换电路的原理图。Figure 4 is a schematic diagram of the third voltage conversion circuit of the carbon resistance temperature sensor constant current source circuit used for low-temperature measurement according to the embodiment of the present invention.

具体实施方式Detailed ways

为使本实用新型实施例的目的、技术方案和优点更加清楚,下面将结合本实用新型实施例,对本实用新型实施例中的技术方案进行清楚、完整地描述,显然,所描述的实施例是本实用新型一部分实施例,而不是全部的实施例。基于本实用新型中的实施例,本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例,都属于本实用新型保护的范围。In order to make the purpose, technical solutions and advantages of the embodiments of the present utility model more clear, the technical solutions in the embodiments of the present utility model will be clearly and completely described below in conjunction with the embodiments of the present utility model. Obviously, the described embodiments are Some embodiments of the present invention are not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present utility model.

下面结合说明书附图以及具体的实施例对本实用新型的技术方案作进一步描述:The technical solution of the present utility model will be further described below in conjunction with the accompanying drawings and specific embodiments of the description:

实施例一Embodiment 1

如图1所示,本实施例的用于低温测量的碳电阻温度传感器恒流源电路包括:第一运算放大器U8、第二运算放大器U9、电容C123、电容C124、电阻R23;所述第一运算放大器U8的1#引脚接地,第一运算放大器U8的4#引脚接参考电压VDD_R,第一运算放大器U8的8#引脚接+5V电源,第一运算放大器U8的5#引脚接-5V电源,电容C123的一端与第一运算放大器U8的8#引脚连接,电容C123的另一端接地,电容C124的一端与第一运算放大器U8的5#引脚连接,电容C124的另一端接地,第一运算放大器U8的7#引脚与电阻R23的一端连接,电阻R23的另一端与第二运算放大器U9的3#引脚连接,第二运算放大器U9的4#引脚接-5V电源,第二运算放大器U9的7#引脚接+5V电源,第二运算放大器U9的6#引脚与第一运算放大器U8的6#引脚连接,第二运算放大器U9的2#引脚与第二运算放大器U9的6#引脚连接;电阻R23与第二运算放大器U9的3#引脚的连接公共点作为恒流源电路的输出端。As shown in Figure 1, the carbon resistance temperature sensor constant current source circuit for low-temperature measurement in this embodiment includes: a first operational amplifier U8, a second operational amplifier U9, a capacitor C123, a capacitor C124, and a resistor R23; the first The 1 # pin of the operational amplifier U8 is connected to ground, the 4 # pin of the first operational amplifier U8 is connected to the reference voltage VDD_R, the 8 # pin of the first operational amplifier U8 is connected to the +5V power supply, and the 5 # pin of the first operational amplifier U8 Connect to the -5V power supply, one end of the capacitor C123 is connected to the 8 # pin of the first operational amplifier U8, the other end of the capacitor C123 is connected to ground, one end of the capacitor C124 is connected to the 5 # pin of the first operational amplifier U8, and the other end of the capacitor C124 is connected to the -5V power supply. One end is connected to ground, the 7 # pin of the first operational amplifier U8 is connected to one end of the resistor R23, the other end of the resistor R23 is connected to the 3 # pin of the second operational amplifier U9, and the 4 # pin of the second operational amplifier U9 is connected to - 5V power supply, the 7 # pin of the second operational amplifier U9 is connected to the +5V power supply, the 6 # pin of the second operational amplifier U9 is connected to the 6 # pin of the first operational amplifier U8, and the 2 # pin of the second operational amplifier U9 pin is connected to the 6 # pin of the second operational amplifier U9; the common point of the connection between the resistor R23 and the 3 # pin of the second operational amplifier U9 is used as the output end of the constant current source circuit.

所述第一运算放大器U8的型号为AD8221,AD8221是一款具有优异共模抑制性能的可编程高性能仪用放大器,由高共模抑制比的运放来构成传感器接口电路,在高精度温度测量电路设计时,能提高低温测量系统的抗干扰性能;AD8221具有噪声低,增益可以编程设置等优点,非常适合桥式电路信号测量等对直流特性要求比较高的领域。The model of the first operational amplifier U8 is AD8221. AD8221 is a programmable high-performance instrument amplifier with excellent common-mode rejection performance. The sensor interface circuit is composed of an operational amplifier with a high common-mode rejection ratio. When designing the measurement circuit, the anti-interference performance of the low-temperature measurement system can be improved; the AD8221 has the advantages of low noise and programmable gain, making it very suitable for bridge circuit signal measurement and other fields that require high DC characteristics.

所述第二运算放大器U9的型号为AD8638,AD8638是一款宽带宽,自动调零的放大器,具有低失调电压、低失调漂移、低噪声,兼顾低成本的同时具有高精度。The model of the second operational amplifier U9 is AD8638. AD8638 is a wide-bandwidth, automatic zero-adjusting amplifier with low offset voltage, low offset drift, low noise, low cost and high precision.

恒流源电路的工作原理:The working principle of constant current source circuit:

例如,输入参考电压VDD_R为2.5V,第一运算放大器U8的输出端得到2.5V的电压,设计R23的阻值为250KΩ,那么恒流源电路的输出为10μA,这样恒流源电路就为碳电阻温度传感器提供了一个稳定的10μA的激励;第二运算放大器U9的作用是实时采集恒流源电路的输出值,送入第一运算放大器U8进行反馈调节,将恒流源电路的输出值稳定在10μA。For example, the input reference voltage VDD_R is 2.5V, the output terminal of the first operational amplifier U8 gets a voltage of 2.5V, and the designed resistance value of R23 is 250KΩ, then the output of the constant current source circuit is 10μA, so the constant current source circuit is carbon The resistance temperature sensor provides a stable 10μA excitation; the function of the second operational amplifier U9 is to collect the output value of the constant current source circuit in real time and send it to the first operational amplifier U8 for feedback adjustment to stabilize the output value of the constant current source circuit. at 10µA.

如图2-4所示,为恒流源电路的供电电路,包括:第一电压转换电路、第二电压转换电路、第三电压转换电路,第一电压转换电路的作用是将220V交流电输入转为±12V直流电,第二电压转换电路的作用是将+12V直流电转换为+5V直流电,第三电压转换电路的作用是将-12V直流电转换为-5V直流电。As shown in Figure 2-4, it is the power supply circuit of the constant current source circuit, including: a first voltage conversion circuit, a second voltage conversion circuit, and a third voltage conversion circuit. The function of the first voltage conversion circuit is to convert the 220V AC input into It is ±12V DC. The function of the second voltage conversion circuit is to convert +12V DC into +5V DC. The function of the third voltage conversion circuit is to convert -12V DC into -5V DC.

如图2所示,为第一电压转换电路的电路原理图,包括:降压斩波模块V1、滤波器V2、保险丝F1、电解电容CE1、电解电容CE2、电容C54、电容C55、稳压二极管TVS9、稳压二极管TVS10;所述降压斩波模块V1采用斩波式220-12/AC-DC模块,所述滤波器V2采用FC-LX1D滤波器,FC-LX1D滤波器适用于对噪声比较敏感的场合。As shown in Figure 2, it is the circuit schematic diagram of the first voltage conversion circuit, including: step-down chopper module V1, filter V2, fuse F1, electrolytic capacitor CE1, electrolytic capacitor CE2, capacitor C54, capacitor C55, and zener diode TVS9, Zener diode TVS10; the step-down chopper module V1 adopts the chopper type 220-12/AC-DC module, the filter V2 adopts the FC-LX1D filter, and the FC-LX1D filter is suitable for noise comparison Sensitive occasions.

所述滤波器V2的3#引脚接220V交流电源的火线,滤波器V2的2#引脚接220V交流电源的零线,滤波器V2的1#引脚接地,滤波器V2的4#引脚与降压斩波模块V1的3#引脚连接,滤波器V2的5#引脚与降压斩波模块V1的2#引脚连接,滤波器V2的1#引脚接地,电解电容CE1的负极接降压斩波模块V1的4#引脚,电解电容CE1的正极接降压斩波模块V1的6#引脚,电解电容CE2的负极接降压斩波模块V1的6#引脚,电解电容CE2的正极接降压斩波模块V1的8#引脚,电容C54的两端分别与降压斩波模块V1的4#引脚与降压斩波模块V1的6#引脚,电容C55的两端分别与降压斩波模块V1的6#引脚与降压斩波模块V1的8#引脚,降压斩波模块V1的6#引脚接地,稳压二极管TVS9的一端与降压斩波模块V1的4#引脚连接,稳压二极管TVS9的另一端接地,稳压二极管TVS10的一端与降压斩波模块V1的8#引脚连接,稳压二极管TVS10的另一端接地,降压斩波模块V1的8#引脚作为+12V电源的输出端与第二电压转换电路的输入端连接,降压斩波模块V1的4#引脚作为-12V电源的输出端与第三电压转换电路的输入端连接。外接220V交流电首先经保险丝连接至FC-LX1D滤波器,经过滤波后接至降压斩波模块V1,将220V交流电转换为±12V电源输出。The 3 # pin of the filter V2 is connected to the live wire of the 220V AC power supply, the 2 # pin of the filter V2 is connected to the neutral wire of the 220V AC power supply, the 1 # pin of the filter V2 is connected to ground, and the 4 # pin of the filter V2 is connected to the ground. The pin is connected to the 3 # pin of the step-down chopper module V1, the 5 # pin of the filter V2 is connected to the 2 # pin of the step-down chopper module V1, the 1 # pin of the filter V2 is connected to the ground, and the electrolytic capacitor CE1 The negative pole of the electrolytic capacitor CE1 is connected to the 4 # pin of the step-down chopper module V1, the positive pole of the electrolytic capacitor CE1 is connected to the 6 # pin of the step-down chopper module V1, and the negative pole of the electrolytic capacitor CE2 is connected to the 6 # pin of the step-down chopper module V1. , the positive electrode of the electrolytic capacitor CE2 is connected to the 8 # pin of the step-down chopper module V1, and the two ends of the capacitor C54 are connected to the 4 # pin of the step-down chopper module V1 and the 6 # pin of the step-down chopper module V1 respectively. The two ends of the capacitor C55 are connected to the 6 # pin of the step-down chopper module V1 and the 8 # pin of the step-down chopper module V1 respectively. The 6 # pin of the step-down chopper module V1 is connected to ground, and one end of the zener diode TVS9 Connect to the 4 # pin of the step-down chopper module V1, the other end of the zener diode TVS9 is connected to ground, one end of the zener diode TVS10 is connected to the 8 # pin of the step-down chopper module V1, and the other end of the zener diode TVS10 Grounded, the 8 # pin of the step-down chopper module V1 serves as the output end of the +12V power supply and is connected to the input end of the second voltage conversion circuit, and the 4 # pin of the step-down chopper module V1 serves as the output end of the -12V power supply and is connected to the ground. The input terminal of the third voltage conversion circuit is connected. The external 220V AC power is first connected to the FC-LX1D filter through a fuse. After filtering, it is connected to the step-down chopper module V1 to convert the 220V AC power into ±12V power output.

如图3所示,为第二电压转换电路的电路原理图,包括:第一线性稳压芯片V3、电容C56、电容C57、电容C58、电容C59、电容C60、电容C61,电阻R30、电阻R31;所述第一线性稳压芯片V3的型号为TPS7A4701,TPS7A4701是一款超低噪声(4μV RMS)LDO,能够提供1A负载并提供正输出电压,外部反馈电阻器配置TPS7A4701的输出电压,此稳压芯片适用于高精度测量电路。As shown in Figure 3, it is the circuit schematic diagram of the second voltage conversion circuit, including: first linear voltage stabilizing chip V3, capacitor C56, capacitor C57, capacitor C58, capacitor C59, capacitor C60, capacitor C61, resistor R30, resistor R31 ; The model of the first linear voltage regulator chip V3 is TPS7A4701. TPS7A4701 is an ultra-low noise (4μV RMS) LDO that can provide 1A load and provide positive output voltage. The external feedback resistor configures the output voltage of TPS7A4701. This stabilizer Pressure chips are suitable for high-precision measurement circuits.

所述第一线性稳压芯片V3的13#引脚、15#引脚、16#引脚连接在一起后再接第一电压转换电路的+12V电源的输出端,电容C58的一端接第一线性稳压芯片V3的13#引脚、电容C58的另一端接地,电容C59的一端接第一线性稳压芯片V3的13#引脚、电容C59的另一端接地,电容C60与电容C61的一端连接在一起后再接第一线性稳压芯片V3的14#引脚、电容C60与电容C61的另一端均接地,电阻R30与电阻R31串联后电阻R30的非串联端与第一线性稳压芯片V3的1#引脚连接、电阻R31的非串联端接地、电阻R30与电阻R31串联公共点接第一线性稳压芯片V3的3#引脚,电容C56与电容C57并联后的其中一个并联公共端接第一线性稳压芯片V3的1#引脚、另一个并联公共端接地,第一线性稳压芯片V3的1#引脚与20#引脚连接在一起,第一线性稳压芯片V3的6#引脚、7#引脚和10#引脚接地,第一线性稳压芯片V3的1#引脚作为第一线性稳压芯片V3的+5V电源输出端。The 13 # pin, 15 # pin, and 16 # pin of the first linear voltage stabilizing chip V3 are connected together and then connected to the output end of the +12V power supply of the first voltage conversion circuit, and one end of the capacitor C58 is connected to the first The 13 # pin of the linear voltage stabilizing chip V3 and the other end of the capacitor C58 are connected to the ground. One end of the capacitor C59 is connected to the 13 # pin of the first linear voltage stabilizing chip V3. The other end of the capacitor C59 is connected to the ground. One end of the capacitor C60 and the capacitor C61 After connecting together, connect the 14 # pin of the first linear voltage stabilizing chip V3, the other ends of the capacitor C60 and the capacitor C61 are grounded, the resistor R30 and the resistor R31 are connected in series, and then the non-series end of the resistor R30 is connected to the first linear voltage stabilizing chip The 1 # pin of V3 is connected, the non-series end of the resistor R31 is connected to the ground, the common point of the resistor R30 and the resistor R31 is connected in series to the 3 # pin of the first linear voltage regulator chip V3, one of the parallel common points of the capacitor C56 and the capacitor C57 is connected in parallel. Terminate the 1 # pin of the first linear voltage stabilizing chip V3, and the other parallel common terminal is connected to ground. The 1 # pin and the 20 # pin of the first linear voltage stabilizing chip V3 are connected together. The first linear voltage stabilizing chip V3 The 6 # pin, 7 # pin and 10 # pin are grounded, and the 1 # pin of the first linear voltage stabilizing chip V3 is used as the +5V power output end of the first linear voltage stabilizing chip V3.

如图4所示,为第三电压转换电路的电路原理图,包括:第二线性稳压芯片V4、电容C62、电容C63、电容C64、电容C65、电容C66、电容C67、电容C68,电阻R32、电阻R33;所述第二线性稳压芯片V4的型号为TPS7A3301,TPS7A3301线性稳压器是一个支持最大输入电压-36V的超低噪声(16μVRMS,72dBPSRR)线性稳压器,能够为最高1A负载供电。As shown in Figure 4, it is the circuit schematic diagram of the third voltage conversion circuit, including: the second linear voltage regulator chip V4, capacitor C62, capacitor C63, capacitor C64, capacitor C65, capacitor C66, capacitor C67, capacitor C68, resistor R32 , resistor R33; the model of the second linear voltage regulator chip V4 is TPS7A3301. The TPS7A3301 linear voltage regulator is an ultra-low noise (16μVRMS, 72dBPSRR) linear voltage regulator that supports a maximum input voltage of -36V and can provide a load of up to 1A. powered by.

所述第二线性稳压芯片V4的13#引脚、15#引脚、16#引脚连接在一起后再接第一电压转换电路的-12V电源的输出端,电容C65的一端接第二线性稳压芯片V4的13#引脚、电容C65的另一端接地,电容C66的一端接第二线性稳压芯片V4的13#引脚、电容C66的另一端接地,电容C67与电容C68并联后的其中一个并联公共端接第二线性稳压芯片V4的14#引脚、另一个并联公共端接地,电容C64的两端分别与第二线性稳压芯片V4的20#引脚以及3#引脚连接,电阻R32与电阻R33串联后电阻R32的非串联端与第二线性稳压芯片V4的20#引脚连接、电阻R33的非串联端与第二线性稳压芯片V4的7#引脚以及21#引脚连接、电阻R32与电阻R33串联公共点接第二线性稳压芯片V4的3#引脚,电容C62与电容C63并联后的其中一个并联公共端接第二线性稳压芯片V4的20#引脚、另一个并联公共端接地,第二线性稳压芯片V4的20#引脚与1#引脚连接在一起,第二线性稳压芯片V4的20#引脚作为第二线性稳压芯片V4的-5V电源输出端。The 13 # pin, 15 # pin, and 16 # pin of the second linear voltage stabilizing chip V4 are connected together and then connected to the output end of the -12V power supply of the first voltage conversion circuit, and one end of the capacitor C65 is connected to the second The 13 # pin of the linear voltage regulator chip V4 and the other end of the capacitor C65 are connected to the ground. One end of the capacitor C66 is connected to the 13 # pin of the second linear voltage regulator chip V4. The other end of the capacitor C66 is connected to the ground. After the capacitor C67 is connected in parallel with the capacitor C68 One of the parallel common terminals is connected to the 14 # pin of the second linear voltage stabilizing chip V4, the other parallel common terminal is connected to ground, and the two ends of the capacitor C64 are respectively connected to the 20 # pin and the 3 # pin of the second linear voltage stabilizing chip V4. Pin connection, after resistor R32 and resistor R33 are connected in series, the non-series end of resistor R32 is connected to the 20 # pin of the second linear voltage stabilizing chip V4, and the non-series connection end of the resistor R33 is connected to the 7 # pin of the second linear voltage stabilizing chip V4. And 21 # pin connection, resistor R32 and resistor R33 are connected in series and the common point is connected to the 3 # pin of the second linear voltage stabilizing chip V4. One of the parallel common terminals after the capacitor C62 and capacitor C63 are connected in parallel is connected to the second linear voltage stabilizing chip V4. The 20 # pin and the other parallel common terminal are connected to the ground. The 20 # pin of the second linear voltage stabilizing chip V4 is connected to the 1 # pin. The 20 # pin of the second linear voltage stabilizing chip V4 is used as the second linear The -5V power output terminal of the voltage stabilizing chip V4.

以上实施例仅用以说明本实用新型的技术方案,而非对其限制;尽管参照前述实施例对本实用新型进行了详细的说明,本领域的普通技术人员应当理解:其依然可以对前述各实施例所记载的技术方案进行修改,或者对其中部分技术特征进行等同替换;而这些修改或者替换,并不使相应技术方案的本质脱离本实用新型各实施例技术方案的精神和范围。The above embodiments are only used to illustrate the technical solution of the present invention, but not to limit it; although the present utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still implement the foregoing implementations. The technical solutions described in the examples are modified, or some of the technical features are equivalently replaced; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of each embodiment of the present invention.

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.
CN202321450914.9U 2023-06-07 2023-06-07 A carbon resistance temperature sensor constant current source circuit for low temperature measurement Active CN220105580U (en)

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CN202321450914.9U CN220105580U (en) 2023-06-07 2023-06-07 A carbon resistance temperature sensor constant current source circuit for low temperature measurement

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CN202321450914.9U CN220105580U (en) 2023-06-07 2023-06-07 A carbon resistance temperature sensor constant current source circuit for low temperature measurement

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