Temperature control circuit for semiconductor refrigerator

Abstract

The present application belongs to the technical field of temperature control circuit, and particularly relates to a temperature control circuit for a semiconductor refrigerator. The temperature control circuit for the semiconductor refrigerator comprises a logic control circuit, a voltage regulating circuit and a current limiting output circuit; the logic control circuit, the voltage regulating circuit and the current limiting output circuit are electrically connected in sequence; the logic control circuit is used for temperature switching; the voltage regulating circuit is used for regulating output voltage; and the current limiting output circuit is used for current limiting of the temperature control circuit. The present application has the characteristics that the TEC circuit can be kept in a steady state, the TEC works in a small power state, and the signal-to-noise ratio of the detector can be improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of temperature control circuits, and particularly relates to a temperature control circuit for a semiconductor refrigerator. BACKGROUND

[0002] A semiconductor refrigerator (TEC) is made by using the Peltier effect of semiconductor materials. With the wide application of TEC semiconductor chips, especially in the aspect of refrigeration, TECs have the advantages of small size, high efficiency, safety and stability, and are widely used in many fields.

[0003] For a four-stage refrigeration TEC, the parameter range of the four-stage refrigeration TEC is a maximum voltage of 8.3 V and a maximum current of 0.5 A. The chips of Texas Instruments TI and Analog Devices ADI are both low-voltage chips within 5 V, and cannot make the TEC work in a full-power state. Since the signal-to-noise ratio is higher when the temperature of the detector is lower, the signal-to-noise ratio cannot reach the desired value when the TEC does not work in a full-power state. At the same time, considering that the detector is relatively expensive, the TEC circuit usually has a voltage and current limiting protection function. In addition, when the TEC is in a full-power working state, the detector will be disturbed, and the noise will become larger.

[0004] Therefore, it is necessary to design a temperature control circuit for a semiconductor refrigerator, which can keep the TEC circuit in a steady state, make the TEC work in a small power state, and improve the signal-to-noise ratio of the detector.

[0005] For example, a TEC temperature control circuit described in Chinese patent document No. CN201810449465.3 includes a single-chip microcomputer, a temperature detection unit, an H-bridge circuit and a TEC unit. The temperature detection unit is connected with the single-chip microcomputer. The H-bridge circuit includes two half-bridge drive chips, and the two half-bridge drive chips are respectively connected with the single-chip microcomputer and the TEC unit. Although the single-chip microcomputer and the half-bridge drive chip are used to build the TEC temperature control circuit, the voltage and current limits of the half-bridge drive chip are greatly improved, ensuring that the TEC temperature control circuit can be applied to a high-power TEC. Since the half-bridge drive chip already has current sampling and overcurrent protection functions, it is not necessary to additionally design a current sampling and overcurrent protection circuit, which greatly reduces the complexity of the H-bridge circuit and improves the system stability. However, the TEC temperature control circuit has the disadvantages that it only applies to a high-power TEC chip, and the detector is disturbed and the noise becomes larger. In addition, the TEC temperature control circuit cannot realize automatic gear shifting. SUMMARY

[0006] The present application is to overcome the prior art, the existing TEC temperature control circuit when the TEC is in full power state, will produce interference to the detector, noise becomes large, resulting in low temperature control precision problem, provides a kind of TEC circuit can be kept in steady state, make TEC be in smaller power state and work, and can improve the signal-to-noise ratio of detector for semiconductor refrigerator temperature control circuit.

[0007] In order to achieve the above-mentioned application purposes, the present application adopts the following technical solutions:

[0008] The temperature control circuit for semiconductor refrigerator includes logic control circuit, voltage regulating circuit and current limiting output circuit;The logic control circuit, voltage regulating circuit and current limiting output circuit are electrically connected in sequence;

[0009] The logic control circuit is used for temperature switching.

[0010] The voltage regulating circuit is used for adjusting output voltage.

[0011] The current limiting output circuit is used for current limiting of temperature control circuit.

[0012] As preferred, the voltage regulating circuit includes operation controller U1, operational amplifier U2, thermistor R29, resistance R2, resistance R3, resistance R6, resistance R7, resistance R8, resistance R9, resistance R10, capacitor C6, capacitor C5, capacitor C4, diode D1, inductor coil L1 and PID regulator;The model of operational amplifier U2 is LTC2053;The model of operation controller U1 is LM2678S-ADJ;Resistance R2 is electrically connected with thermistor R29 and the 2nd pin of operational amplifier U2 respectively;Thermistor R29 is grounded;The 1st pin and the 4th pin of operational amplifier U2 are both grounded;The 8th pin of operational amplifier U2 is connected with 5V power supply;The 5th pin of operational amplifier U2 is electrically connected with resistance R9;Resistance R9 is electrically connected with capacitor C6 and resistance R10 respectively, and capacitor C6 is grounded;The 6th pin of operational amplifier U2 is electrically connected with resistance R6, resistance R10 and capacitor C5 respectively;The 7th pin of operational amplifier U2 is electrically connected with resistance R6, capacitor C5 and PID regulator respectively;The 3rd pin and the 6th pin of operation controller U1 are electrically connected;The 2nd pin of operation controller U1 is electrically connected with inductor coil L1 and the negative electrode of diode D1 respectively;The positive electrode of diode D1 is grounded and electrically connected with capacitor C4;Capacitor C4 is electrically connected with inductor coil L1 and resistance R3 respectively;Resistance R3 is electrically connected with resistance R7 and resistance R8 respectively;Resistance R7 is electrically connected with PID regulator.

[0013] As preferred, the PID regulator comprises resistance R1, resistance R4, resistance R5, capacitor C1, capacitor C2, capacitor C3 and operational amplifier U3; the model of the operational amplifier U3 is AD8605ARTZ; the resistance R4 is electrically connected with the 7th pin of the operational amplifier U2, resistance R6 and capacitor C5 respectively; the resistance R5 is electrically connected with the resistance R4 and capacitor C3 respectively; the 4th pin of the operational amplifier U3 is electrically connected with the resistance R5, capacitor C3, resistance R1 and capacitor C1 respectively; the 2nd pin of the operational amplifier U3 is connected with 5V power supply; the 5th pin of the operational amplifier U3 is grounded; the 1st pin of the operational amplifier U3 is electrically connected with capacitor C1, capacitor C2 and resistance R7 respectively.

[0014] As preferred, the current limiting output circuit comprises a shottky follower and a current limiting circuit; the shottky follower is electrically connected with the current limiting circuit.

[0015] As preferred, the shottky follower comprises resistance R14, triode Q2, resistance R11 and diode D2; the collector of the triode Q2 is electrically connected with the resistance R14; the emitter of the triode Q2 is electrically connected with the resistance R11; the resistance R11 is electrically connected with the positive pole of the diode D2 and the current limiting circuit respectively; the negative pole of the diode D2 is electrically connected with the resistance R14 and the base of the triode Q2 respectively.

[0016] As preferred, the current limiting circuit comprises resistance R13, resistance R16, triode Q3, resistance R12, capacitor C7, diode D3, MOS tube Q1 and resistance R15; the resistance R13 is electrically connected with the resistance R11, positive pole of the diode D2, capacitor C7, resistance R12 and emitter of the triode Q3 respectively; the resistance R16 is electrically connected with the resistance R13, capacitor C7, collector of the triode Q3, positive pole of the diode D3 and resistance R15 respectively; the resistance R16 is grounded; the resistance R12 is electrically connected with the base of the triode Q3, negative pole of the diode D3 and source of the MOS tube Q1 respectively; the resistance R15 is electrically connected with the gate of the triode Q3; the drain of the triode Q3 is electrically connected with the semiconductor refrigerator TEC.

[0017] As preferred, the logic control circuit comprises a comparator U5, an AND gate chip U4, a soft start circuit, a diode D4, a diode D5, a resistor R18, a resistor R27, a resistor R28, a capacitor C9, an OR gate chip U6, an OR gate chip U7, an electronic switch U8, a first temperature circuit, a second temperature circuit, a third temperature circuit and a fourth temperature circuit; the model of the comparator U5 is AD8605ARTZ; the model of the AND gate chip U4 is SN74LVC1G08; the models of the OR gate chip U6 and the OR gate chip U7 are both 74AUP1G79; the 2nd pin of the comparator U5 is connected with a 5V power supply; the 5th pin of the comparator U5 is grounded and electrically connected with the 3rd pin of the AND gate chip U4; the 5th pin of the AND gate chip U4 is connected with a 5V power supply; the 4th pin of the AND gate chip U4 is electrically connected with the anode of the diode D4; the 1st pin of the comparator U5 is electrically connected with the soft start circuit; the anode of the diode D5 is electrically connected with the soft start circuit; the cathode of the diode D5 is electrically connected with the resistor R18, the cathode of the diode D4 and the 1st pin of the OR gate chip U6 respectively; the 2nd pin of the OR gate chip U6 is electrically connected with the 4th pin of the OR gate chip U6 and the 1st pin of the OR gate chip U7 respectively; the 3rd pin of the OR gate chip U6 is electrically connected with the 3rd pin of the OR gate chip U7; the 2nd pin of the OR gate chip U7 is electrically connected with the 4th pin of the OR gate chip U7;

[0018] The model of the electronic switch U8 is ADG659YRUZ; the 16th pin of the electronic switch U8 is electrically connected with a 5V power supply and a capacitor C9 respectively; the capacitor C9 is grounded; the 10th pin of the electronic switch U8 is electrically connected with a resistor R28; the 9th pin of the electronic switch U8 is electrically connected with a resistor R27; the resistor R28 is grounded; the resistor R27 is grounded; the 6th pin, the 7th pin and the 8th pin of the electronic switch U8 are all grounded; the 1st pin of the electronic switch U8 is electrically connected with the first temperature circuit; the 2nd pin of the electronic switch U8 is electrically connected with the second temperature circuit; the 4th pin of the electronic switch U8 is electrically connected with the third temperature circuit; the 5th pin of the electronic switch U8 is electrically connected with the fourth temperature circuit.

[0019] As preferred, the soft start circuit comprises a resistor R17, a capacitor C8 and a MOS tube Q4; the resistor R17 is electrically connected with the 1st pin of the comparator U5, the drain of the MOS tube Q4 and the anode of the diode D5 respectively; the gate of the MOS tube Q4 is electrically connected with the resistor R17 and the capacitor C8 respectively; the capacitor C8 is grounded and electrically connected with the source of the MOS tube Q4.

[0020] As preferred, the first temperature circuit comprises a resistor R19 and a resistor R23; the resistor R19 is electrically connected with the resistor R23 and the 1st pin of the electronic switch U8 respectively;

[0021] The two-gear temperature circuit comprises resistors R20 and R24; the resistor R20 is electrically connected with the resistor R24 and the second pin of the electronic switch U8 respectively;

[0022] The three-gear temperature circuit comprises resistors R21 and R25; the resistor R21 is electrically connected with the resistor R25 and the fourth pin of the electronic switch U8 respectively;

[0023] The four-gear temperature circuit comprises resistors R22 and R26; the resistor R22 is electrically connected with the resistor R26 and the fifth pin of the electronic switch U8 respectively.

[0024] Compared with the prior art, the present application has the following advantages: (1) compared with the MAX1968 and LTC1923 special TEC chips, the voltage and current range of the present application is wider than that of the MAX1968, and the cost is lower than that of the LTC1923, the devices are ordinary materials, and the selection can be better replaced; (2) the temperature control precision of the present application is high, the power can be 50-60W, and can be applied to high-power loads, and the PID regulator is fed back to accelerate the balance; (3) the temperature automatic gear shifting of the present application can greatly improve the signal-to-noise ratio of the detector; (4) the present application adopts hardware feedback, and does not need software algorithm; (5) the output limiting voltage and the output voltage in the present application can be changed, which can be applied to other TECs, and is convenient for debugging. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a circuit diagram of a voltage regulating circuit in the temperature control circuit for the semiconductor refrigerator of the present application;

[0026] Figure 2 It is a circuit diagram of a current limiting output circuit in the temperature control circuit for the semiconductor refrigerator of the present application;

[0027] Figure 3 It is a circuit diagram of a logic control circuit in the temperature control circuit for the semiconductor refrigerator of the present application;

[0028] Figure 4 It is a principle block diagram of temperature switching of the temperature control circuit for the semiconductor refrigerator of the present application;

[0029] Figure 5 It is a principle block diagram of the temperature control circuit for the semiconductor refrigerator of the present application. DETAILED DESCRIPTION

[0030] In order to more clearly illustrate the embodiments of the present application, the specific implementation of the present application will be described below with reference to the drawings. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings and other embodiments can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0031] Example:

[0032] This invention discloses a temperature control circuit for a semiconductor cooler, comprising a logic control circuit, a voltage regulation circuit, and a current limiting output circuit; the logic control circuit, the voltage regulation circuit, and the current limiting output circuit are electrically connected in sequence.

[0033] The logic control circuit is used for temperature switching;

[0034] The voltage regulation circuit is used to regulate the output voltage;

[0035] The current-limiting output circuit is used to limit the current of the temperature control circuit.

[0036] like Figure 1 As shown, the voltage regulation circuit includes an operational controller U1, an operational amplifier U2, a thermistor R29, resistors R2, R3, R6, R7, R8, R9, and R10, capacitors C6, C5, and C4, a diode D1, an inductor L1, and a PID controller; the operational amplifier U2 is an LTC2053; the operational controller U1 is an LM2678S-ADJ; resistor R2 is electrically connected to the thermistor R29 and pin 2 of the operational amplifier U2; the thermistor R29 is grounded; pins 1 and 4 of the operational amplifier U2 are both grounded; pin 8 of the operational amplifier U2 is connected to a 5V power supply; the operational amplifier U2's... Pin 5 is electrically connected to resistor R9; resistor R9 is electrically connected to capacitor C6 and resistor R10 respectively, and capacitor C6 is grounded; pin 6 of operational amplifier U2 is electrically connected to resistor R6, resistor R10 and capacitor C5 respectively; pin 7 of operational amplifier U2 is electrically connected to resistor R6, capacitor C5 and PID controller respectively; pins 3 and 6 of operational controller U1 are electrically connected; pin 2 of operational controller U1 is electrically connected to inductor L1 and the negative terminal of diode D1 respectively; the positive terminal of diode D1 is grounded and electrically connected to capacitor C4; capacitor C4 is electrically connected to inductor L1 and resistor R3 respectively; resistor R3 is electrically connected to resistor R7 and resistor R8 respectively; resistor R7 is electrically connected to PID controller.

[0037] The PID regulator comprises resistors R1, R4, R5, capacitors C1, C2, C3 and an operational amplifier U3; the model of the operational amplifier U3 is AD8605ARTZ; the resistor R4 is electrically connected with the 7th pin of the operational amplifier U2, the resistor R6 and the capacitor C5 respectively; the resistor R5 is electrically connected with the resistor R4 and the capacitor C3 respectively; the 4th pin of the operational amplifier U3 is electrically connected with the resistor R5, the capacitor C3, the resistor R1 and the capacitor C1 respectively; the 2nd pin of the operational amplifier U3 is connected with a 5V power supply; the 5th pin of the operational amplifier U3 is grounded; and the 1st pin of the operational amplifier U3 is electrically connected with the capacitor C1, the capacitor C2 and the resistor R7 respectively.

[0038] In the voltage regulating circuit, the resistors R6 and R10 are gain adjustment; the components R4, R5, C3, R1, C2, C1 and U3 constitute a PID regulator; the U3 output participates in the voltage output adjustment of U1, and VO=R3*(VFB / R3+VFB / R8+(VFB-V1) / R7); the voltage range of VI is 0 to 5V; the lowest output of the chip is 1.2V; and the highest output of the chip is 12V.

[0039] As shown in Figure 2 , the current limiting output circuit comprises a transistor follower and a current limiting circuit; and the transistor follower is electrically connected with the current limiting circuit.

[0040] The transistor follower comprises a resistor R14, a transistor Q2, a resistor R11 and a diode D2; the collector of the transistor Q2 is electrically connected with the resistor R14; the emitter of the transistor Q2 is electrically connected with the resistor R11; the resistor R11 is electrically connected with the positive electrode of the diode D2 and the current limiting circuit respectively; and the negative electrode of the diode D2 is electrically connected with the resistor R14 and the base of the transistor Q2 respectively.

[0041] The current limiting circuit comprises a resistor R13, a resistor R16, a transistor Q3, a resistor R12, a capacitor C7, a diode D3, a MOS transistor Q1 and a resistor R15; the resistor R13 is electrically connected with the resistor R11, the positive electrode of the diode D2, the capacitor C7, the resistor R12 and the emitter of the transistor Q3 respectively; the resistor R16 is electrically connected with the resistor R13, the capacitor C7, the collector of the transistor Q3, the positive electrode of the diode D3 and the resistor R15 respectively; the resistor R16 is grounded; the resistor R12 is electrically connected with the base of the transistor Q3, the negative electrode of the diode D3 and the source of the MOS transistor Q1 respectively; the resistor R15 is electrically connected with the gate of the transistor Q3; and the drain of the transistor Q3 is electrically connected with the semiconductor refrigerator TEC.

[0042] In the current limiting circuit, the capacitor C7 is used for slow start, and the current limiting formula is 0.7 / R12.

[0043] As shown in Figure 3As shown, the logic control circuit includes a comparator U5, an AND gate chip U4, a soft start circuit, a diode D4, a diode D5, a resistor R18, a resistor R27, a resistor R28, a capacitor C9, an OR gate chip U6, an OR gate chip U7, an electronic switch U8, a first temperature circuit, a second temperature circuit, a third temperature circuit and a fourth temperature circuit; the model of the comparator U5 is AD8605ARTZ; the model of the AND gate chip U4 is SN74LVC1G08; the models of the OR gate chip U6 and the OR gate chip U7 are both 74AUP1G79; the 2nd pin of the comparator U5 is connected with a 5V power supply; the 5th pin of the comparator U5 is grounded and electrically connected with the 3rd pin of the AND gate chip U4; the 5th pin of the AND gate chip U4 is connected with a 5V power supply; the 4th pin of the AND gate chip U4 is electrically connected with the anode of the diode D4; the 1st pin of the comparator U5 is electrically connected with the soft start circuit; the anode of the diode D5 is electrically connected with the soft start circuit; the cathode of the diode D5 is electrically connected with the resistor R18, the cathode of the diode D4 and the 1st pin of the OR gate chip U6 respectively; the 2nd pin of the OR gate chip U6 is electrically connected with the 4th pin of the OR gate chip U6 and the 1st pin of the OR gate chip U7 respectively; the 3rd pin of the OR gate chip U6 is electrically connected with the 3rd pin of the OR gate chip U7; the 2nd pin of the OR gate chip U7 is electrically connected with the 4th pin of the OR gate chip U7;

[0044] The model of the electronic switch U8 is ADG659YRUZ; the 16th pin of the electronic switch U8 is electrically connected with a 5V power supply and a capacitor C9 respectively; the capacitor C9 is grounded; the 10th pin of the electronic switch U8 is electrically connected with a resistor R28; the 9th pin of the electronic switch U8 is electrically connected with a resistor R27; the resistor R28 is grounded; the resistor R27 is grounded; the 6th pin, the 7th pin and the 8th pin of the electronic switch U8 are all grounded; the 1st pin of the electronic switch U8 is electrically connected with the first temperature circuit; the 2nd pin of the electronic switch U8 is electrically connected with the second temperature circuit; the 4th pin of the electronic switch U8 is electrically connected with the third temperature circuit; the 5th pin of the electronic switch U8 is electrically connected with the fourth temperature circuit.

[0045] The soft start circuit includes a resistor R17, a capacitor C8 and a MOS tube Q4; the resistor R17 is electrically connected with the 1st pin of the comparator U5, the drain of the MOS tube Q4 and the anode of the diode D5 respectively; the gate of the MOS tube Q4 is electrically connected with the resistor R17 and the capacitor C8 respectively; the capacitor C8 is grounded and electrically connected with the source of the MOS tube Q4.

[0046] The first temperature circuit includes a resistor R19 and a resistor R23; the resistor R19 is electrically connected with the resistor R23 and the 1st pin of the electronic switch U8 respectively;

[0047] The second temperature circuit includes a resistor R20 and a resistor R24; the resistor R20 is electrically connected with the resistor R24 and the 2nd pin of the electronic switch U8 respectively;

[0048] The third temperature circuit comprises resistors R21 and R25; the resistor R21 is electrically connected with the resistor R25 and the fourth pin of the electronic switch U8 respectively;

[0049] The fourth temperature circuit comprises resistors R22 and R26; the resistor R22 is electrically connected with the resistor R26 and the fifth pin of the electronic switch U8 respectively.

[0050] The component U8 is a four-to-one electronic switch, corresponding to the S1, S2, S3 and S4 four-grade temperature. The U5 is a comparator, outputting a high level when the temperature does not reach. The components R17, C8 and Q4 constitute a slow start circuit, used for resetting, and the gate chip U4 is an AND gate. The U4 and U5 output control the U6, and the U6 and U7 are D flip-flops, used as a counter. When a pulse is received, the counter counts once, and different temperatures are selected according to different counts. The temperature is divided into 00, 01, 10 and 11 four grades. When the output is 11, i.e. the U4 outputs a high level, the counting stops.

[0051] As shown in Figure 4 and Figure 5 , the working principle of the circuit of the present application is as follows:

[0052] After power-on, the electronic switch U8 defaults to the first grade working, and the set temperature is -90 degrees. The TEC starts working, and the voltage value of the thermistor and the set temperature value are used for error amplification. The PID output and the operation control LM2678 adjust the output voltage. The power supply of R7, R3, R8 and the operational amplifier U3 needs to be calculated. The four parameters determine the maximum and minimum voltage of the TEC power supply. The TEC starts working at full power of 12V output. The maximum power of the circuit is 60W, and two-stage current limiting is added in the rear stage, so as to ensure that the TEC will not overvoltage and overcurrent.

[0053] If the set temperature is not reached after 10S, the logic control circuit is switched to -80 degrees. If the set temperature is not reached in the rear, it is switched to -70 and -60 degrees in turn, until the temperature is switched to the fourth grade, and the temperature switching stops. As shown in Figure 4 , the DCDC direct current converter will interfere with the detector when working at full power. Only the front stage is balanced, and the signal-to-noise ratio of the detector can be improved.

[0054] Compared with the MAX1968 and LTC1923 special TEC chips, the voltage and current of the application are wider than the range of MAX1968, and the cost is lower than LTC1923, the device is a common material, and it is better to replace the selection; The temperature control precision of the application is high, the power can reach 50-60W, can be applied to high-power load, feedback with PID regulator, accelerate balance; The application automatically shifts gears, which can greatly improve the signal-to-noise ratio of the detector; The application uses hardware feedback, without software algorithm; The output voltage and output voltage in the application can be changed, which can be applied to other TECs, and is convenient for debugging.

[0055] The above only describes the preferred embodiments and principles of the application in detail, and for ordinary skilled persons in the art, according to the idea provided by the application, there will be changes in the specific implementation mode, and these changes should be regarded as the protection scope of the application.

Claims

1. A temperature control circuit for a semiconductor refrigerator, characterized in that, It includes a logic control circuit, a voltage regulation circuit, and a current limiting output circuit; the logic control circuit, the voltage regulation circuit, and the current limiting output circuit are electrically connected in sequence. The logic control circuit is used for temperature switching; The voltage regulation circuit is used to regulate the output voltage; The current-limiting output circuit is used to limit the current of the temperature control circuit; The logic control circuit includes comparator U5, AND gate chip U4, soft-start circuit, diode D4, diode D5, resistor R18, resistor R27, resistor R28, capacitor C9, OR gate chip U6, OR gate chip U7, electronic switch U8, first-level temperature circuit, second-level temperature circuit, third-level temperature circuit, and fourth-level temperature circuit; the comparator U5 is model AD8605ARTZ; the AND gate chip U4 is model SN74LVC1G08; the OR gate chips U6 and U7 are both model 74AUP1G79; pin 2 of comparator U5 is connected to a 5V power supply; pin 5 of comparator U5 is grounded and connected to the AND gate chip... Pin 3 of chip U4 is electrically connected; pin 5 of AND gate chip U4 is connected to a 5V power supply; pin 4 of AND gate chip U4 is electrically connected to the positive terminal of diode D4; pin 1 of comparator U5 is electrically connected to the soft-start circuit; the positive terminal of diode D5 is electrically connected to the soft-start circuit; the negative terminal of diode D5 is electrically connected to resistor R18, the negative terminal of diode D4, and pin 1 of OR gate chip U6; pin 2 of OR gate chip U6 is electrically connected to pin 4 of OR gate chip U6 and pin 1 of OR gate chip U7; pin 3 of OR gate chip U6 is electrically connected to pin 3 of OR gate chip U7; pin 2 of OR gate chip U7 is electrically connected to pin 4 of OR gate chip U7. The electronic switch U8 is model ADG659YRUZ; pin 16 of the electronic switch U8 is electrically connected to the 5V power supply and capacitor C9; capacitor C9 is grounded; pin 10 of the electronic switch U8 is electrically connected to resistor R28; pin 9 of the electronic switch U8 is electrically connected to resistor R27; resistor R28 is grounded; resistor R27 is grounded; pins 6, 7, and 8 of the electronic switch U8 are all grounded; pin 1 of the electronic switch U8 is electrically connected to the first-level temperature circuit; pin 2 of the electronic switch U8 is electrically connected to the second-level temperature circuit; pin 4 of the electronic switch U8 is electrically connected to the third-level temperature circuit; pin 5 of the electronic switch U8 is electrically connected to the fourth-level temperature circuit.

2. The temperature control circuit for a semiconductor cooler according to claim 1, characterized in that, The voltage regulation circuit includes an operational controller U1, an operational amplifier U2, a thermistor R29, resistors R2, R3, R6, R7, R8, R9, and R10, capacitors C6, C5, and C4, a diode D1, an inductor L1, and a PID controller. The operational amplifier U2 is an LTC2053; the operational controller U1 is an LM2678S-ADJ; resistor R2 is electrically connected to the thermistor R29 and pin 2 of the operational amplifier U2; the thermistor R29 is grounded; pins 1 and 4 of the operational amplifier U2 are grounded; pin 8 of the operational amplifier U2 is connected to a 5V power supply; pin 5 of the operational amplifier U2... The pin is electrically connected to resistor R9; resistor R9 is electrically connected to capacitor C6 and resistor R10 respectively, and capacitor C6 is grounded; pin 6 of operational amplifier U2 is electrically connected to resistor R6, resistor R10 and capacitor C5 respectively; pin 7 of operational amplifier U2 is electrically connected to resistor R6, capacitor C5 and PID controller respectively; pins 3 and 6 of operational controller U1 are electrically connected; pin 2 of operational controller U1 is electrically connected to inductor L1 and the negative terminal of diode D1 respectively; the positive terminal of diode D1 is grounded and electrically connected to capacitor C4; capacitor C4 is electrically connected to inductor L1 and resistor R3 respectively; resistor R3 is electrically connected to resistor R7 and resistor R8 respectively; resistor R7 is electrically connected to PID controller.

3. The temperature control circuit for a semiconductor refrigerator according to claim 2, characterized in that, The PID controller includes resistors R1, R4, and R5, capacitors C1, C2, and C3, and operational amplifier U3. Operational amplifier U3 is model AD8605ARTZ. Resistor R4 is electrically connected to pin 7 of operational amplifier U2, resistor R6, and capacitor C5. Resistor R5 is electrically connected to resistor R4 and capacitor C3. Pin 4 of operational amplifier U3 is electrically connected to resistor R5, capacitor C3, resistor R1, and capacitor C1. Pin 2 of operational amplifier U3 is connected to a 5V power supply. Pin 5 of operational amplifier U3 is grounded. Pin 1 of operational amplifier U3 is electrically connected to capacitors C1 and C2, and resistor R7.

4. The temperature control circuit for a semiconductor refrigerator according to claim 1, characterized in that, The current-limiting output circuit includes an emitter follower and a current-limiting circuit; the emitter follower is electrically connected to the current-limiting circuit.

5. The temperature control circuit for a semiconductor refrigerator according to claim 4, characterized in that, The emitter follower includes a resistor R14, a transistor Q2, a resistor R11, and a diode D2; the collector of transistor Q2 is electrically connected to resistor R14; the emitter of transistor Q2 is electrically connected to resistor R11; resistor R11 is electrically connected to the anode of diode D2 and the current limiting circuit, respectively; the cathode of diode D2 is electrically connected to resistor R14 and the base of transistor Q2, respectively.

6. The temperature control circuit for a semiconductor refrigerator according to claim 5, characterized in that, The current limiting circuit includes resistors R13 and R16, transistor Q3, resistor R12, capacitor C7, diode D3, MOSFET Q1, and resistor R15. Resistor R13 is electrically connected to resistor R11, the anode of diode D2, capacitor C7, resistor R12, and the emitter of transistor Q3. Resistor R16 is electrically connected to resistor R13, capacitor C7, the collector of transistor Q3, the anode of diode D3, and resistor R15. Resistor R16 is grounded. Resistor R12 is electrically connected to the base of transistor Q3, the cathode of diode D3, and the source of MOSFET Q1. Resistor R15 is electrically connected to the gate of transistor Q3. The drain of transistor Q3 is electrically connected to the thermoelectric cooler TEC.

7. The temperature control circuit for a semiconductor refrigerator according to claim 1, characterized in that, The soft-start circuit includes a resistor R17, a capacitor C8, and a MOSFET Q4; the resistor R17 is electrically connected to the first pin of the comparator U5, the drain of the MOSFET Q4, and the positive terminal of the diode D5; the gate of the MOSFET Q4 is electrically connected to the resistor R17 and the capacitor C8; the capacitor C8 is grounded and electrically connected to the source of the MOSFET Q4.

8. The temperature control circuit for a semiconductor cooler according to claim 1, characterized in that, The first-level temperature circuit includes resistor R19 and resistor R23; resistor R19 is electrically connected to resistor R23 and pin 1 of electronic switch U8 respectively. The two-stage temperature circuit includes resistors R20 and R24; resistor R20 is electrically connected to resistor R24 ​​and pin 2 of electronic switch U8, respectively. The three-level temperature circuit includes resistors R21 and R25; resistor R21 is electrically connected to resistor R25 and pin 4 of electronic switch U8, respectively. The four-level temperature circuit includes resistors R22 and R26; resistor R22 is electrically connected to resistor R26 and pin 5 of electronic switch U8.

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