阅读说明：本技术 一种高精度测温控温电路 (High-precision temperature measuring and controlling circuit ) 是由 李永富 郭进 刘俊良 费宬 康佳龙 刘兆军 赵显� 于 2019-09-24 设计创作，主要内容包括：本发明公开了一种高精度测温控温电路。该电路具体包括测温电路、单片机和控温电路,测温电路中又包括单臂电桥测温电路、仪表放大电路和模数转换电路,控温电路中又包括数模转换电路、同相放大电路、低压差线性稳压电路、H桥控制电路。该电路通过测温电路能够准确测量和采集温度值,然后通过控温电路又可以实现对半导体制冷片进行高精度的温控控制,实现了在测温控温方面降低噪声、减少功耗、提高效率的目的。(The invention discloses a high-precision temperature measuring and controlling circuit. The circuit specifically comprises a temperature measuring circuit, a single chip microcomputer and a temperature control circuit, wherein the temperature measuring circuit further comprises a single-arm bridge temperature measuring circuit, an instrument amplifying circuit and an analog-to-digital conversion circuit, and the temperature control circuit further comprises a digital-to-analog conversion circuit, an in-phase amplifying circuit, a low-dropout linear voltage stabilizing circuit and an H-bridge control circuit. The circuit can accurately measure and collect temperature values through the temperature measuring circuit, and then can realize high-precision temperature control of the semiconductor refrigeration sheet through the temperature control circuit, so that the aims of reducing noise, reducing power consumption and improving efficiency in the aspects of temperature measurement and temperature control are fulfilled.)

1. A high-precision temperature measurement and control circuit is characterized by comprising a temperature measurement circuit, a single chip microcomputer and a temperature control circuit, wherein the temperature measurement circuit also comprises a single-arm bridge temperature measurement circuit, an instrument amplification circuit and an analog-to-digital conversion circuit; in the temperature measuring circuit, a single-arm bridge temperature measuring circuit senses temperature change and converts the temperature change into a voltage signal, the voltage signal is input into an instrument amplifying circuit to be amplified, the amplified analog voltage signal is converted into a digital voltage signal through an analog-to-digital conversion circuit and then input into a single chip microcomputer, and the single chip microcomputer obtains accurately measured temperature measuring data; in the temperature control circuit, the single chip microcomputer outputs temperature control data to the digital-to-analog conversion circuit, the digital-to-analog conversion circuit converts the temperature control data into analog temperature control voltage, the analog temperature control voltage is amplified by the in-phase amplification circuit and then output to the H bridge control circuit through the low-voltage-difference linear voltage stabilizing circuit to obtain high-precision temperature control voltage, and the H bridge control circuit supplies power and controls temperature to the thermoelectric cooler accurately.

2. The high-precision temperature measuring and controlling circuit according to claim 1, wherein the single-arm bridge temperature measuring circuit comprises a first bias resistor, a second bias resistor, a third bias resistor, a fourth bias resistor, a fifth bias resistor and a platinum resistor for sensing temperature change; the first bias resistor, the second bias resistor and the fourth bias resistor are sequentially connected in series between a reference voltage and a grounding terminal, and the third bias resistor, the platinum resistor and the fifth bias resistor are also connected in series between the reference voltage and the grounding terminal.

3. The high-precision temperature measuring and controlling circuit according to claim 2, wherein the meter amplifying circuit comprises a chip AD623, a connection point of the platinum resistor and the third bias resistor is connected to a positive input end of the chip AD623, and a connection point of the first bias resistor and the second bias resistor is connected to a negative input end of the chip AD 623.

4. The high-precision temperature measurement and control circuit according to claim 3, wherein a voltage output end of the chip AD623 is connected to a forward input end of an analog-to-digital conversion chip ADS8320 in the analog-to-digital conversion circuit through a series resistor, and an output end of the analog-to-digital conversion chip ADS8320 is connected to the single chip microcomputer.

5. The high-precision temperature measurement and control circuit according to claim 1, wherein the digital-to-analog conversion circuit comprises a digital-to-analog conversion chip MAX5136, the single chip microcomputer is a control chip STM32F031G6U6, an interconnection interface between the digital-to-analog conversion chip MAX5136 and the control chip STM32F031G6U6 comprises a chip selection end, a clock end and a data end, the control chip STM32F031G6U6 transmits temperature control data to the chip MAX5136 through the interconnection interface, and the temperature control data is converted into analog temperature control voltage output through the chip MAX 5136.

6. The high-precision temperature measuring and controlling circuit according to claim 5, wherein the in-phase amplifying circuit comprises an operational amplifier chip LT6015, the analog temperature control voltage from the digital-to-analog converting chip MAX5136 is inputted to a forward input terminal of the operational amplifier chip LT6015, a reverse input terminal of the chip LT6015 is connected to an output terminal of the chip LT6015 through a series feedback capacitor, an output terminal of the chip LT6015 is further connected to an output resistor, the other end of the output resistor is connected to a reverse input terminal of the chip LT6015 through a feedback resistor, and the reverse input terminal of the chip LT6015 is further connected to a ground resistor and grounded.

7. The circuit of claim 6, wherein the low dropout linear regulator circuit comprises a chip LT3083, and an output voltage of an output terminal of the chip LT6015 passing through an output resistor is input to a setting terminal of the chip LT3083, thereby realizing voltage setting of the low dropout linear regulator circuit.

8. The high-precision temperature measuring and controlling circuit according to claim 7, wherein the DC-DC converting circuit comprises a chip LT8643S, the input terminal and the output terminal of the chip LT3083 are further fed back to the switching power supply chip LT8643S through a control transistor, the feedback terminal of the switching power supply chip LT8643S is electrically connected to the collector of the control transistor, the output terminal of the switching power supply chip LT8643S is electrically connected to the emitter of the control transistor after being connected to an inductor, the emitter of the control transistor is connected to the input terminal of the chip LT3083, and the base of the control transistor is electrically connected to the output terminal of the chip LT3083 after being connected to a current limiting resistor in series.

9. The high-precision temperature measurement and control circuit according to claim 7 or 8, wherein the H bridge control circuit comprises 4 NMOS transistors and 2 PMOS transistors, wherein the source electrodes of the first PMOS transistor and the second PMOS transistor are electrically connected with the output voltage of the chip LT3083, the drain electrodes of the first NMOS transistor and the second NMOS transistor are also electrically connected with the output voltage of the chip LT3083, the drain electrode of the first PMOS transistor, the source electrode of the first NMOS transistor and the drain electrode of the third NMOS transistor are electrically connected with the first input end of the semiconductor chilling plate, the drain electrode of the second PMOS transistor, the source electrode of the second NMOS transistor and the drain electrode of the fourth NMOS transistor are electrically connected with the second input end of the semiconductor chilling plate, and the source electrode of the third NMOS transistor and the source electrode of the fourth NMOS transistor are both grounded; the grid electrodes of a second PMOS tube, a first NMOS tube and a fourth NMOS tube in the H-bridge control circuit are electrically connected with one control pin of the single chip microcomputer, and the grid electrodes of the first PMOS tube, the second NMOS tube and the third NMOS tube are electrically connected with the other control pin of the single chip microcomputer.

Technical Field

The invention relates to the technical field of refrigeration and temperature control, in particular to a high-precision temperature measuring and controlling circuit.

Background

The semiconductor refrigerating chip (TEC) is a solid refrigerating mode, and directly transfers heat to realize heat transfer from a refrigerating surface to a radiating surface by means of holes and electrons in motion, so that refrigeration is realized. Compared with the traditional refrigerating system, the TEC has the advantages of no need of refrigerant, no noise, no pollution, high reliability, long service life and the like. Due to the fact that thermal inertia of the TEC is small, rapid cooling or heating can be achieved.

Disclosure of Invention

The invention mainly solves the technical problem of providing a high-precision temperature measuring and controlling circuit, and solves the problems of large power consumption, large noise, low efficiency and low precision in the existing temperature control technology based on a semiconductor refrigeration chip.

In order to solve the technical problems, the invention adopts a technical scheme that a high-precision temperature measurement and control circuit is provided, and the high-precision temperature measurement and control circuit comprises a temperature measurement circuit, a single chip microcomputer and a temperature control circuit, wherein the temperature measurement circuit also comprises a single-arm bridge temperature measurement circuit, an instrument amplification circuit and an analog-to-digital conversion circuit, and the temperature control circuit also comprises a digital-to-analog conversion circuit, an in-phase amplification circuit, a low-dropout linear voltage stabilizing circuit and an H-bridge control circuit; in the temperature measuring circuit, a single-arm bridge temperature measuring circuit senses temperature change and converts the temperature change into a voltage signal, the voltage signal is input into an instrument amplifying circuit to be amplified, the amplified analog voltage signal is converted into a digital voltage signal through an analog-to-digital conversion circuit and then input into a single chip microcomputer, and the single chip microcomputer obtains accurately measured temperature measuring data; in the temperature control circuit, the single chip microcomputer outputs temperature control data to the digital-to-analog conversion circuit, the digital-to-analog conversion circuit converts the temperature control data into analog temperature control voltage, the analog temperature control voltage is amplified by the in-phase amplification circuit and then output to the H bridge control circuit through the low-voltage-difference linear voltage stabilizing circuit to obtain high-precision temperature control voltage, and the H bridge control circuit supplies power and controls temperature to the thermoelectric cooler accurately.

In another embodiment of the high-precision temperature measuring and controlling circuit, the single-arm bridge temperature measuring circuit comprises a first bias resistor, a second bias resistor, a third bias resistor, a fourth bias resistor, a fifth bias resistor and a platinum resistor for sensing temperature change; the first bias resistor, the second bias resistor and the fourth bias resistor are sequentially connected in series between a reference voltage and a grounding terminal, and the third bias resistor, the platinum resistor and the fifth bias resistor are also connected in series between the reference voltage and the grounding terminal.

In another embodiment of the high-precision temperature measurement and control circuit, the instrument amplification circuit comprises a chip AD623, a connection point of the platinum resistor and the third bias resistor is connected to the positive input end of the chip AD623, and a connection point of the first bias resistor and the second bias resistor is connected to the negative input end of the chip AD 623.

In another embodiment of the high-precision temperature measurement and control circuit, a voltage output end of the chip AD623 is connected to a forward input end of an analog-to-digital conversion chip ADs8320 in the analog-to-digital conversion circuit through a series resistor, and an output end of the analog-to-digital conversion chip ADs8320 is connected to a single chip microcomputer.

In another embodiment of the high-precision temperature measurement and control circuit, the digital-to-analog conversion circuit includes a digital-to-analog conversion chip MAX5136, the single chip microcomputer is a control chip STM32F031G6U6, an interconnection interface between the digital-to-analog conversion chip MAX5136 and the control chip STM32F031G6U6 includes a chip selection end, a clock end and a data end, the control chip STM32F031G6U6 transmits temperature control data to the chip MAX5136 through the interconnection interface, and the temperature control data is converted into analog temperature control voltage through the chip MAX5136 and output.

In another embodiment of the high-precision temperature measurement and control circuit of the invention, the in-phase amplifier circuit comprises an operational amplifier chip LT6015, the analog temperature control voltage from the digital-to-analog conversion chip MAX5136 is input to the forward input end of the operational amplifier chip LT6015, the reverse input end of the chip LT6015 is connected to the output end of the chip LT6015 through a series feedback capacitor, the output end of the chip LT6015 is further connected to an output resistor, the other end of the output resistor is connected to the reverse input end of the chip LT6015 through a feedback resistor, and the reverse input end of the chip LT6015 is connected to a ground resistor and grounded.

In another embodiment of the high-precision temperature measuring and controlling circuit of the invention, the low dropout linear regulator circuit comprises a chip LT3083, and an output voltage of an output end of the chip LT6015 passing through an output resistor is input to a setting end of the chip LT3083, thereby realizing voltage setting of the low dropout linear regulator circuit.

In another embodiment of the high-precision temperature measurement and control circuit, the DC-DC conversion circuit comprises a chip LT8643S, the input end and the output end of the chip LT3083 are further fed back to a switching power supply chip LT8643S through a control triode, the feedback end of the switching power supply chip LT8643S is electrically connected with the collector electrode of the control triode, the output end of the switching power supply chip LT8643S is connected with the emitter electrode of the control triode after being connected with an inductor, the emitter electrode of the control triode is electrically connected with the input end of the chip LT3083, and the base electrode of the control triode is electrically connected with the output end of the chip LT3083 after being connected with a current-limiting resistor in series.

In another embodiment of the high-precision temperature measurement and control circuit, the H-bridge control circuit comprises 4 NMOS transistors and 2 PMOS transistors, wherein the source electrodes of the first PMOS transistor and the second PMOS transistor are electrically connected with the output voltage of the chip LT3083, the drain electrodes of the first NMOS transistor and the second NMOS transistor are also electrically connected with the output voltage of the chip LT3083, the drain electrode of the first PMOS transistor, the source electrode of the first NMOS transistor and the drain electrode of the third NMOS transistor are electrically connected with the first input end of the semiconductor chilling plate, the drain electrode of the second PMOS transistor, the source electrode of the second NMOS transistor and the drain electrode of the fourth NMOS transistor are electrically connected with the second input end of the chilling semiconductor plate, and the source electrode of the third NMOS transistor and the source electrode of the fourth NMOS transistor are both grounded; the grid electrodes of a second PMOS tube, a first NMOS tube and a fourth NMOS tube in the H-bridge control circuit are electrically connected with one control pin of the single chip microcomputer, and the grid electrodes of the first PMOS tube, the second NMOS tube and the third NMOS tube are electrically connected with the other control pin of the single chip microcomputer.

The invention has the beneficial effects that: the invention discloses a high-precision temperature measuring and controlling circuit which specifically comprises a temperature measuring circuit, a single chip microcomputer and a temperature controlling circuit, wherein the temperature measuring circuit also comprises a single-arm bridge temperature measuring circuit, an instrument amplifying circuit and an analog-to-digital conversion circuit, and the temperature controlling circuit also comprises a digital-to-analog conversion circuit, an in-phase amplifying circuit, a low-dropout linear voltage stabilizing circuit and an H-bridge control circuit. The circuit can accurately measure and collect temperature values through the temperature measuring circuit, and then can realize high-precision temperature control of the semiconductor refrigeration sheet through the temperature control circuit, so that the aims of reducing noise, reducing power consumption and improving efficiency in the aspects of temperature measurement and temperature control are fulfilled.

Drawings

FIG. 1 is a block diagram of an embodiment of a high-precision temperature measurement and control circuit according to the present invention;

FIG. 2 is a circuit diagram of a one-arm bridge thermometric circuit, a meter amplifying circuit and an analog-digital conversion circuit in another embodiment of the high-precision thermometric and temperature control circuit according to the invention;

FIG. 3 is a circuit diagram of a single chip microcomputer in another embodiment of the high-precision temperature measurement and control circuit according to the present invention;

FIG. 4 is a digital-to-analog conversion circuit diagram in another embodiment of the high-precision temperature measurement and control circuit according to the present invention;

FIG. 5 is a circuit diagram of an in-phase amplifier circuit in another embodiment of the high-precision temperature measurement and control circuit according to the present invention;

FIG. 6 is a diagram of a low dropout linear voltage regulator circuit according to another embodiment of the present invention;

FIG. 7 is a circuit diagram of a switching power supply in another embodiment of the high-precision temperature measurement and control circuit according to the present invention;

FIG. 8 is a circuit diagram of an H-bridge control circuit in another embodiment of the high-precision temperature measurement and control circuit according to the present invention;

FIG. 9 is a diagram of a power conversion circuit in another embodiment of the high accuracy temperature measurement and control circuit according to the present invention;

FIG. 10 is a diagram of a power conversion circuit in another embodiment of the high accuracy temperature measurement and control circuit according to the present invention;

FIG. 11 is a diagram of a power conversion circuit in another embodiment of the high accuracy temperature measurement and control circuit according to the present invention;

FIG. 12 is a circuit diagram of a reference voltage generation circuit in another embodiment of the high-precision temperature measurement and control circuit according to the invention.

Detailed Description

In order to facilitate an understanding of the invention, the invention is described in more detail below with reference to the accompanying drawings and specific examples. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It is to be noted that, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Fig. 1 shows a block diagram of an embodiment of the high-precision temperature measuring and controlling circuit of the present invention. In fig. 1, the temperature measuring circuit generally includes a temperature measuring circuit, a single chip, and a temperature control circuit, the temperature measuring circuit includes a single-arm bridge temperature measuring circuit, an instrument amplifier circuit, and an analog-to-digital conversion circuit, and the temperature control circuit includes a digital-to-analog conversion circuit, an in-phase amplifier circuit, a low-dropout linear voltage regulator circuit, and an H-bridge control circuit, wherein the low-dropout linear voltage regulator circuit is powered by a DC-DC power conversion circuit. Furthermore, in the temperature measuring circuit, the temperature change is sensed into a voltage change signal through the single-arm bridge temperature measuring circuit, then the voltage change signal is input into the instrument amplifying circuit to be amplified, the amplified analog voltage signal is converted into a digital voltage signal through the analog-to-digital conversion circuit and then the digital voltage signal is input into the single chip microcomputer, and the single chip microcomputer obtains accurately measured temperature measuring data. In the temperature control circuit, the single chip microcomputer outputs temperature control data to the digital-to-analog conversion circuit, the digital-to-analog conversion circuit converts the temperature control data into analog temperature control voltage, the analog temperature control voltage is amplified by the in-phase amplification circuit and then output to the H-bridge control circuit through the low-voltage-difference linear voltage stabilizing circuit to obtain high-precision temperature control voltage, and the H-bridge control circuit supplies power to the thermoelectric refrigerator (including the semiconductor refrigerating piece) accurately, so that high-precision temperature control of the semiconductor refrigerating piece is achieved.

Further preferably, as shown in fig. 2, the one-arm bridge thermometric circuit includes a first bias resistor R1, a second bias resistor R2, a third bias resistor R3, a fourth bias resistor R22, a fifth bias resistor R23, and a platinum resistor P2 for sensing temperature change. It can be seen that the first bias resistor R1, the second bias resistor R2 and the fourth bias resistor R22 are sequentially and serially connected between the reference voltage vref1.2 (the reference voltage is dc 1.2V) and the ground terminal GND, and another serial branch is also connected between the reference voltage vref1.2 and the ground terminal GND in parallel, that is, the third bias resistor R3, the platinum resistor P2 and the fifth bias resistor R23 are also serially connected between the reference voltage vref1.2 and the ground terminal GND.

Further, the instrument amplifying circuit comprises a chip AD623, the connection point of a platinum resistor P2 and a third bias resistor R3 is connected to the positive input end IN + of the chip AD623, the connection point of a first bias resistor R1 and a second bias resistor R2 is connected to the negative input end IN-of the chip AD623, a capacitor C3 is arranged between the positive input end IN + and the negative input end IN-, the capacitor C3 is used for improving common mode rejection and removing common mode interference signals, the positive input end IN + is connected with a bypass grounding capacitor C2, and the negative input end IN-is connected with a bypass grounding capacitor C1.

Preferably, the temperature measuring element is a platinum resistor, because the platinum resistor has the characteristics of wide measuring range, high precision, stable performance and the like. When the temperature is reduced, the resistance of the platinum resistor is reduced, the voltage at the connection point of the platinum resistor P2 and the third bias resistor R3 is reduced, the voltage at the connection point of the first bias resistor R1 and the second bias resistor R2 is unchanged, so that the voltage difference between the two connection points is changed, the two connection points are respectively connected with the positive input end and the negative input end of the chip AD623, and the voltage is adjusted and amplified by the instrument amplifier and then input to the analog-to-digital conversion chip ADS 8320. Since the input voltage range of the chip ADS8320 is 0-2.5V, the amplification range of the chip AD623 is 0-2.5V.

Further, a voltage output end OUT of the chip AD623 is connected to a forward input end of an analog-to-digital conversion chip ADs8320 in the analog-to-digital conversion circuit through a series resistor R50, a reference voltage end VREF of the analog-to-digital conversion chip ADs8320 is connected to a voltage VREF _2.5 (direct current 2.5V), and an output end OUT of the analog-to-digital conversion chip ADs8320 is connected to the single chip microcomputer.

Further, as shown in fig. 3, the single chip is a control chip STM32F031G6U6, and as can be seen from fig. 2, an interconnection interface between the chip and the chip ADS8320 in fig. 2 includes a chip select terminal CS, a clock terminal DCLK, and a data terminal OUT-1, and temperature measurement data (16-bit digital signals) can be input into the control chip STM32F031G6U6 through the three ports of the interface. The control chip STM32F031G6U6 can obtain a temperature control data (also 16-bit digital signal) through PID algorithm by further temperature measuring data, and then the temperature control data is input into the digital-to-analog conversion circuit to be converted into an analog temperature control voltage signal.

Here, the PID algorithm is a closed-loop control algorithm that performs correction based on output feedback of a control target, and corrects the deviation according to a rated value or a standard value when the deviation between the actual value and the planned value is measured. PID is an abbreviation for proportional (contribution), Integral (Integral), Differential (Differential coefficient). The deviation of the controlled object can be effectively corrected by the combination of the three algorithms, so that the controlled object reaches a stable state.

Preferably, the calculation method of the temperature control data DA _ Add calculated by the PID algorithm is as follows:

DA_Add＝P×(Temperature_Err-Temperature_Err_His1)

+I×Temperature_Err+D×(Temperature_Err-2*Temperature_Err_His1+Temperature_Err_His2)；

wherein, the Temperature _ Err is a Temperature error between the current measured Temperature and the target Temperature, and the Temperature _ Err _ His1 is an adjacent Temperature error acquired last time. Temperature _ Err _ His2 is the Temperature error of the previous acquisition that was adjacent, i.e., the Temperature error of the previous acquisition that was adjacent before Temperature _ Err _ His 1. After debugging, an optimal P, I, D coefficient can be obtained, the PID coefficient is substituted into a formula, DA _ Add can be obtained when the temperature changes, and the value of the DA _ Add is transmitted to a subsequent digital-to-analog conversion chip.

Preferably, as shown in fig. 4, the digital-to-analog conversion circuit includes a digital-to-analog conversion chip MAX5136, and as shown in fig. 3, an interconnection interface between the chip MAX5136 and the control chip STM32F031G6U6 in fig. 3 includes a chip select terminal/CS, a clock terminal SCLK and a data terminal DIN, the control chip STM32F031G6U6 transmits temperature control data to the chip MAX5136 through the interconnection interface, and the temperature control data is converted into an analog temperature control voltage through the chip MAX5136 and output.

Further, as shown in fig. 5, the non-inverting amplifier circuit includes an operational amplifier chip LT6015, the analog temperature control voltage DAC _ O _0 from the chip MAX5136 is input to a forward input terminal of the chip LT6015, an inverting input terminal of the chip LT6015 is connected to an output terminal of the chip LT6015 through a series feedback capacitor C35, an output terminal of the chip LT6015 is further connected to an output resistor R15, the other end of the output resistor 15 is connected to the inverting input terminal of the chip LT6015 through a feedback resistor R7, and the inverting input terminal of the chip LT6015 is further connected to a ground resistor R8 and grounded. The feedback capacitor and the output resistor are arranged to prevent the self-excitation effect of the operational amplifier.

Further, as shown in fig. 6, the low dropout linear regulator includes a chip LT3083, and as can be seen from fig. 5, an output voltage VO _0 of an output terminal of the chip LT6015 passing through an output resistor is input to a SET terminal SET of the chip LT3083, so that voltage setting of the low dropout linear regulator can be realized.

Preferably, in order to achieve more accurate control voltage output, the input end and the output end of the chip LT3083 are further fed back to the switching power supply chip through the control transistor. As shown in fig. 7, the feedback terminal FB of the switching power chip LT8643S is electrically connected to the collector of the control transistor Q1, the output terminal SW of the switching power chip LT8643S is electrically connected to the emitter of the control transistor Q1 after being connected to the inductor L1, the emitter of the control transistor Q1 is electrically connected to the input terminal of the chip LT3083 in fig. 6 (VPTEC is shown in fig. 6 and 7 as a common connection point), and the base of the control transistor Q1 is electrically connected to the output terminal of the chip LT3083 in fig. 6 after being connected in series to a current limiting resistor R12 (VTEC is shown in fig. 6 and 7 as a common connection point).

According to the characteristics of the triode, when the voltages of the base and the emitter are less than or equal to the turn-on voltage, no current passes through the collector. As shown in fig. 6, the voltage of VTEC is determined by the voltage of the SET pin of the chip 3083, VPTEC provides the input voltage to the chip 3083, as shown in fig. 7, the voltage of VPTEC is always higher than VTEC by one turn-on voltage (the turn-on voltages of different transistors may be different, the turn-on voltage of the invention is 0.7V with 2N3906, so there is a voltage difference problem of 0.7V). When the voltage of the FB pin rises, the chip LT8643 can enable the output VPTEC to become smaller, when the difference value between the VPTEC and the VTEC is reduced to be only the starting voltage of the triode, no current passes through the collector, the VPTEC does not change any more, and therefore the VPTEC is always higher than the VTEC by one starting voltage.

This design makes the output of the switching power supply chip LT8643S follow the change of the output of the chip LT3083, and makes it possible to make the output voltage of the chip LT3083 always lower than the input voltage by 0.7V. The design adopts the method that the switching power supply follows the output of the low dropout linear regulator (LDO) chip, so that the energy waste of the LDO chip is reduced to the greatest extent, and the working efficiency of the circuit is improved. Compared with the traditional TEC control chip, the design can enable the power supply of the TEC to be started from 0V, and the temperature control effect is more accurate. Preferably, two LT3083 are used for parallel connection to realize large-current output.

Here, in order to eliminate noise generated by the switching power chip LT8643S as much as possible, the voltage output by the switching power chip LT8643S is supplied to an H-bridge control circuit driving a semiconductor cooler (TEC) through a low dropout linear regulator (LDO) chip with a high Power Supply Rejection Ratio (PSRR), i.e., the chip LT 3083. And the control signal output by the singlechip control chip controls six control ends of the H-bridge control circuit and controls two ends of the TEC to refrigerate or heat. Preferably, the switching power supply chip generates strong radiation noise, so that the switching power supply and the LDO are placed in an electromagnetic isolation environment, and the linear refrigeration control circuit has high power supply efficiency while keeping low noise.

Further, as shown in fig. 8, the H-bridge control circuit includes 4 NMOS transistors and 2 PMOS transistors, wherein the sources of the first PMOS transistor Q1 and the second PMOS transistor Q2 are both electrically connected to the output voltage VTEC of the chip LT3083, the drains of the first NMOS transistor Q3 and the second NMOS transistor Q4 are also both electrically connected to the output voltage VTEC of the chip LT3083, the drain of the first PMOS transistor Q1, the source of the first NMOS transistor Q3, and the drain of the third NMOS transistor Q5 are all electrically connected to the first input terminal of the semiconductor chilling plate TEC, the drain of the second PMOS transistor Q2, the source of the second NMOS transistor Q4, and the drain of the fourth NMOS transistor Q6 are all electrically connected to the second input terminal of the semiconductor chilling plate TEC, and the source of the third NMOS transistor Q5 and the source of the fourth NMOS transistor Q6 are all grounded. Further, the H-bridge control circuit is controlled by the single chip STM32F031G6U6 shown in fig. 3, wherein pin 9 (High) is connected to the gates of the second PMOS transistor Q2, the first NMOS transistor Q3 and the fourth NMOS transistor Q6 in the H-bridge circuit, and pin 13 (Low) is connected to the gates of the first PMOS transistor Q1, the second NMOS transistor Q4 and the third NMOS transistor Q5.

Here, when the gate of the first PMOS transistor Q1 is set to low level 0V and the source voltage is also 0V, the first PMOS transistor Q1 cannot be turned on. The source of the first NMOS transistor Q3 is connected in parallel with the drain of the first PMOS transistor Q1, and the gate of the first NMOS transistor Q3 is connected to the opposite potential of the gate of the first PMOS transistor Q1. At this time, even if the H-bridge supply voltage is too low to turn on the first PMOS transistor Q1, the first NMOS transistor Q3 may still be turned on, so that current flows from the source of Q3 of the first NMOS transistor to supply power to the TEC. This design allows the H-bridge circuit to operate from 0V.

Further, as shown in fig. 9, the DC-DC conversion circuit includes a chip TPS54061, which can convert an input high DC voltage VCC1 (e.g. 12V DC voltage) into a low DC voltage VCC2 (e.g. 5V DC voltage) for output. Then, V3p3 (for example, DC 5V to 3.3V) as shown in fig. 1 can be further obtained by DC-DC conversion from VCC2, and as shown in fig. 10, the DC-DC conversion chip used here is MIC 5207. While VCC3 in fig. 6 can also be converted from VCC1 (for example, from direct current 12V to 10V), as shown in fig. 11, the DC-DC conversion chip used here is ADP7142 AUJZ.

Still further, for vref1.2 and vref2.5 in fig. 2, the vref1.2 is obtained by connecting a voltage V3p3 in series with a resistor R23 to a voltage reference chip TL4051a12, and a connection point between the resistor R23 and the voltage reference chip TL4051a12 is the reference voltage vref1.2, as shown in fig. 11. Similarly, in fig. 11, vref2.5 is obtained by connecting a voltage V3p3 in series with a resistor R18 and then to a voltage reference chip TL4050a25, and the connection point of the resistor R18 and the voltage reference chip TL4050a25 is the reference voltage vref2.5. The voltage conversion circuits can improve the power conversion efficiency, reduce the power consumption and ensure higher voltage accuracy and stability.

Therefore, the high-precision temperature measurement and control circuit comprises a temperature measurement circuit, a single chip microcomputer and a temperature control circuit, wherein the temperature measurement circuit also comprises a single-arm bridge temperature measurement circuit, an instrument amplification circuit and an analog-to-digital conversion circuit, and the temperature control circuit also comprises a digital-to-analog conversion circuit, an in-phase amplification circuit, a low-dropout linear voltage stabilizing circuit and an H-bridge control circuit. The circuit can accurately measure and collect temperature values through the temperature measuring circuit, and then can realize high-precision temperature control of the semiconductor refrigeration sheet through the temperature control circuit, so that the aims of reducing noise, reducing power consumption and improving efficiency in the aspects of temperature measurement and temperature control are fulfilled.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structural changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to other related technical fields, are included in the scope of the present invention.