Temperature control circuit

Abstract

The utility model relates to the technical field of temperature protection, and discloses a temperature control circuit with hysteresis function and high reliability, which comprises a signal control circuit (100) and a drive circuit (200), the signal control circuit (100) at least comprises an NTC detection module (110), an amplification module (120), a comparison module (140) and a hysteresis circuit (150), the hysteresis circuit (150) is used for changing the voltage value of a reference signal, and the hysteresis circuit (150) is used for controlling the NTC detection module (110), the amplification module (120), the comparison module (140) and the hysteresis circuit (150). And the level state of the control signal output by the comparison module (140) is adjusted.

Description

Technical Field

[0001] This utility model relates to the field of temperature protection technology, and more specifically, to a temperature control circuit. Background Technology

[0002] NTC protection is a commonly used protection module in fan control circuits. Currently, in existing protection circuits, when the temperature exceeds the over-temperature detection point, the resistance of the thermistor decreases, and the voltage input to the comparator circuit is higher than the reference voltage, thus controlling the fan to stop; when the temperature drops below the over-temperature detection point, the resistance of the thermistor increases, and the voltage input to the comparator circuit is lower than the reference voltage, thus controlling the fan to start.

[0003] During the above process, when the temperature hovers near the over-temperature detection point, it will cause frequent switching between over-temperature operation and normal operation, resulting in the fan frequently turning on or the power supply being turned off repeatedly, which will affect the user experience. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a temperature control circuit with hysteresis function and high reliability, which addresses the shortcomings of the prior art, such as frequent switching between over-temperature operation and normal operation when the temperature hovers near the over-temperature detection point, causing the fan to start frequently or the power supply to be cut off back and forth.

[0005] The technical solution adopted by this utility model to solve its technical problem is: to construct a temperature control circuit, which has the following features:

[0006] A signal control circuit, which is disposed within the temperature control circuit, is used to acquire the temperature signal of the load and output a control signal according to the current temperature signal.

[0007] The drive circuit has its power input terminal connected to the power supply terminal to receive the drive voltage.

[0008] The signal input terminal of the driving circuit is connected to the output terminal of the signal control circuit, and is used to receive the control signal, which is used to control the on / off state of the driving circuit; wherein,

[0009] The signal control circuit includes at least an NTC detection module, an amplification module, a comparison module, and a hysteresis circuit.

[0010] The NTC detection module is used to detect the temperature signal of the load.

[0011] The input terminal of the amplification module is connected to the output terminal of the NTC detection module, and is used to receive the temperature signal.

[0012] One input terminal of the comparison module is connected to the reference voltage terminal for receiving the reference signal.

[0013] The other input terminal of the comparison module is connected to the output terminal of the amplification module, and is used to receive the temperature signal amplified by the amplification module.

[0014] The output terminal of the comparison module is connected to the signal input terminal of the drive circuit.

[0015] The first terminal of the hysteresis circuit is connected to the output terminal of the comparator module.

[0016] The second terminal of the hysteresis circuit is connected to the reference voltage terminal.

[0017] The third terminal of the hysteresis circuit is connected to one input terminal of the comparison module.

[0018] The hysteresis circuit is used to change the voltage value of the reference signal to adjust the level of the control signal output by the comparison module.

[0019] In some embodiments, the hysteresis circuit includes a first MOSFET and an eighth resistor.

[0020] The gate of the first MOS transistor is connected to the output terminal of the comparator module.

[0021] The drain of the first MOSFET is connected to the reference voltage terminal.

[0022] The source of the first MOS transistor is connected to one end of the eighth resistor.

[0023] The other end of the eighth resistor is connected to one input terminal of the comparison module.

[0024] In some implementations, a voltage divider module is also included, with a first terminal connected to the reference voltage terminal.

[0025] The second terminal of the voltage divider module is connected to one input terminal of the comparator module.

[0026] The third terminal of the voltage divider module is connected to the common terminal.

[0027] In some embodiments, the voltage divider module includes a sixth resistor and a seventh resistor connected in series.

[0028] One end of the sixth resistor is coupled to the reference voltage terminal.

[0029] The other end of the sixth resistor and one end of the seventh resistor are connected to an input terminal of the comparison module.

[0030] The other end of the seventh resistor is connected to the common terminal.

[0031] In some embodiments, the NTC detection module includes a first resistor and a thermistor connected in series.

[0032] One end of the first resistor and one end of the thermistor are connected to an input terminal of the amplification module.

[0033] The other end of the first resistor is connected to the 12V power supply.

[0034] The other end of the thermistor is connected to the other input terminal and the common terminal of the amplification module, respectively.

[0035] In some embodiments, the amplification module includes at least one amplifier.

[0036] The non-inverting input of the amplifier is connected to one end of the first resistor and one end of the thermistor via a second resistor.

[0037] The inverting input of the amplifier is connected to the other end of the thermistor via a third resistor.

[0038] The output of the amplifier is connected to the other input of the comparator module.

[0039] In some implementations, the comparison module includes at least a comparator.

[0040] The non-inverting input of the comparator is connected to the connection terminals of the sixth and seventh resistors.

[0041] The non-inverting input of the comparator is also connected to the other end of the eighth resistor.

[0042] The inverting input of the comparator is connected to the output of the amplifier via a fifth resistor.

[0043] The output of the comparator is connected to the signal input of the drive circuit.

[0044] In some embodiments, the driving circuit includes at least a second MOSFET and a third MOSFET.

[0045] The gate of the second MOSFET is connected to the output of the comparator via the first diode and the tenth resistor.

[0046] The drain of the second MOSFET is connected to the +12V power supply terminal through the twelfth resistor.

[0047] The gate of the third MOS transistor is connected to the drain of the second MOS transistor.

[0048] The source of the third MOSFET is connected to the +12V power supply terminal.

[0049] The drain of the third MOS transistor is connected to one end of the load.

[0050] The source of the second MOS transistor and the other end of the load are respectively connected to the common terminal.

[0051] The temperature control circuit described in this invention includes a signal control circuit and a drive circuit. The signal control circuit includes at least an NTC detection module, an amplification module, a comparison module, and a hysteresis circuit. The hysteresis circuit is used to change the voltage value of the reference signal to adjust the level of the control signal output by the comparison module. Compared with existing technologies, by adjusting or changing the voltage value of the reference signal through the hysteresis circuit, the temperature value can be lowered to a second temperature state before the corresponding control signal is output. This effectively avoids frequent triggering between normal and abnormal states due to abnormal temperature rise, thereby reducing the on / off frequency of the load (corresponding to the fan), extending the fan's on / off life, and improving the user experience. Attached Figure Description

[0052] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0053] Figure 1 This is a circuit diagram of an embodiment of the temperature control circuit provided by this utility model. Detailed Implementation

[0054] To provide a clearer understanding of the technical features, objectives, and effects of this utility model, the specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0055] like Figure 1 As shown, in the first embodiment of the temperature control circuit of this utility model, the temperature control circuit 10 includes a signal control circuit 100 and a drive circuit 200.

[0056] The signal control circuit 100 has the functions of signal acquisition / amplification / comparison and output control signal. It is used to acquire the temperature signal of the load / electrical equipment, convert it into a voltage signal, amplify / compare it, and then output a control signal (high level or low level) according to the current comparison result.

[0057] The drive circuit 200 is used to receive the control signal output by the signal control circuit 100, and control the on / off state of the load according to the level state (high level or low level) of the input control signal;

[0058] The signal control circuit 100 includes an NTC detection module 110, an amplification module 120, a voltage divider module 130, a comparison module 140, and a hysteresis circuit 150.

[0059] The NTC detection module 110 is used to detect the temperature signal of the load / electrical equipment.

[0060] The temperature signal may include a first temperature state and a second temperature state, where the temperature value of the first temperature state is approximately 60°C and the temperature value of the second temperature state is approximately 40°C.

[0061] The amplification module 120 is used to receive the temperature signal input from the NTC detection module 110, convert it into a voltage signal, amplify it, and output it to the comparison module 140.

[0062] The voltage divider module 130 is used to receive a 12V voltage signal and process the input voltage signal to form a reference voltage.

[0063] The comparison module 140 has the function of signal comparison. One of its input terminals is used to receive the reference voltage, and the other terminal is used to receive the voltage signal input from the amplification module 120. It compares the voltage signal with the reference voltage and then outputs a control signal (high level or low level) according to the comparison result.

[0064] The hysteresis circuit 150 is used to receive a 12V voltage signal, divide it, and then input it to an input terminal of the comparison module 140 to change the voltage value of the reference voltage at an input terminal of the comparison module 140.

[0065] Specifically, the signal control circuit 100 is set in the temperature control circuit to acquire the temperature signal of the load / electrical equipment, amplify and compare the acquired temperature signal, compare the current temperature signal with the reference signal, and output a control signal (high level or low level) according to the current comparison result.

[0066] Furthermore, the power input terminal of the drive circuit 200 is connected to the power supply terminal (corresponding to +12V) to receive the drive voltage.

[0067] The signal input terminal of the drive circuit 200 is connected to the output terminal of the signal control circuit 100, and is used to receive the control signal input from the signal control circuit 100. This control signal is used to control the on / off state of the drive circuit 200; wherein,

[0068] The signal control circuit 100 includes at least an NTC detection module 110, an amplification module 120, a comparison module 140, and a hysteresis circuit 150.

[0069] NTC detection module 110 is used to detect the temperature signal of the load / electrical equipment and output the temperature signal to amplification module 120;

[0070] The input terminal of the amplification module 120 is connected to the output terminal of the NTC detection module 110 to receive the temperature signal, convert the temperature signal into a voltage signal, amplify it, and output it to the comparison module 140.

[0071] One input terminal of the comparator module 140 is connected to the reference voltage terminal (corresponding to 12V) to receive the reference signal formed after voltage division.

[0072] Another input terminal of the comparison module 140 is connected to the output terminal of the amplification module 120, which is used to receive the temperature signal (which is a voltage signal at this time) amplified by the amplification module 120, compare the temperature signal with the reference signal, and then output a control signal according to the comparison result;

[0073] The output terminal of the comparison module 140 is connected to the signal input terminal of the drive circuit 200, and the control signal is input to the drive circuit 200 to control its on / off state.

[0074] The first terminal of the hysteresis circuit 150 is connected to the output terminal of the comparator module 140, and is used to receive the level signal output by the comparator module 140.

[0075] The second terminal of the hysteresis circuit 150 is connected to the reference voltage terminal (corresponding to 12V).

[0076] The third terminal of the hysteresis circuit 150 is connected to one input terminal of the comparator module 140.

[0077] When the input level signal is high, the hysteresis circuit 150 is turned on, thereby applying the voltage output from the reference voltage terminal (corresponding to 12V) to one input terminal of the comparator module 140 through the hysteresis circuit 150. This causes the voltage at one input terminal of the comparator module 140 to increase, i.e., the reference voltage increases, thereby changing the voltage value at one input terminal of the reference signal input to the comparator module 140, so as to adjust the level state of the control signal output by the comparator module 140.

[0078] Using this technical solution, by adjusting or changing the voltage value of the reference signal through the hysteresis circuit 150, the control signal can be output when the temperature value drops to the second temperature state. This effectively avoids frequent triggering between normal and abnormal states due to abnormal temperature rise, thereby reducing the on / off frequency of the load (corresponding to the fan), which helps to extend the on / off life of the fan and improve the user experience.

[0079] In some implementations, to pull up the reference voltage, a first MOSFET Q1 and an eighth resistor R8 can be provided in the hysteresis circuit 150, wherein the first MOSFET Q1 is selected as an N-channel MOSFET, which has the function of a switch;

[0080] Specifically, the gate of the first MOSFET Q1 is connected to the output terminal of the comparator module 140 to receive the level signal output by the comparator module 140.

[0081] The drain of the first MOSFET Q1 is connected to the reference voltage terminal (corresponding to 12V) to receive a 12V voltage signal.

[0082] The source of the first MOSFET Q1 is connected to one end of the eighth resistor R8.

[0083] The other end of the eighth resistor R8 is connected to one input terminal of the comparator module 140.

[0084] When the output signal of the comparator module 140 is low, the first MOSFET Q1 is in the off state, and the reference signal (or reference voltage) at one input terminal of the comparator module 140 remains unchanged.

[0085] When the output signal of the comparator module 140 is high, the first MOSFET Q1 is turned on, and the reference signal (or reference voltage) at one input terminal of the comparator module 140 is pulled high.

[0086] In some implementations, to ensure the reliability of the input reference voltage, a voltage divider module 130 can be included in the temperature control circuit. The first terminal of the voltage divider module 130 is connected to the reference voltage terminal (corresponding to 12V) to receive the 12V voltage signal and perform voltage division on the 12V voltage.

[0087] The second terminal of the voltage divider module 130 is connected to one input terminal of the comparator module 140, and is used to receive the reference voltage after voltage division.

[0088] The third terminal of the voltage divider module 130 is connected to the common terminal.

[0089] The voltage divider module 130 includes a sixth resistor R6 and a seventh resistor R7 connected in series.

[0090] One end of the sixth resistor R6 is coupled to the reference voltage terminal (corresponding to 12V).

[0091] The other end of the sixth resistor R6 and one end of the seventh resistor R7 are connected to one input terminal of the comparator module 140. The input 12V voltage is divided by the sixth resistor R6 and the seventh resistor R7, and the resulting reference voltage is then input to one input terminal of the comparator module 140.

[0092] The other end of the seventh resistor R7 is connected to the common terminal.

[0093] In some embodiments, the NTC detection module 110 includes a first resistor R1 and a thermistor RT1 connected in series.

[0094] One end of the first resistor R1 and one end of the thermistor RT1 are connected to an input terminal of the amplifier module 120.

[0095] The other end of the first resistor R1 is connected to the 12V power supply terminal (corresponding to 12V).

[0096] The other end of the thermistor RT1 is connected to the other input terminal and the common terminal of the amplifier module 120.

[0097] In some implementations, to amplify the input temperature signal, an amplifier U1A can be provided in the amplification module 120, which has the function of signal amplification.

[0098] Specifically, the non-inverting input (corresponding to pin 5) of amplifier U1A is connected to one end of the first resistor R1 and one end of the thermistor RT1 through the second resistor R2.

[0099] The inverting input of amplifier U1A (corresponding to pin 6) is connected to the other end of the thermistor RT1 through the third resistor R3.

[0100] The inverting input (pin 6) of amplifier U1A is connected to the output (pin 7) of amplifier U1A through the fourth resistor R4. The resistance of the fourth resistor R4 is 150K, which means the amplification factor is 150 times.

[0101] The output terminal of amplifier U1A (corresponding to pin 7) is connected to the other input terminal of comparator module 140.

[0102] In some implementations, to ensure the stability of the output control signal, a comparator U1B can be provided in the comparison module 140, which has the function of comparing signals and outputting control signals based on the comparison result.

[0103] Specifically, the non-inverting input (corresponding to pin 3) of comparator U1B is connected to the connection terminals of the sixth resistor R6 and the seventh resistor R7 to receive the reference voltage after voltage division.

[0104] The non-inverting input (corresponding to pin 3) of comparator U1B is also connected to the other end of the eighth resistor R8, which is used to receive another voltage signal input from the output terminal (corresponding to pin 1) of comparator U1B when the first MOSFET Q1 is controlled to be turned on. This voltage signal is superimposed on the reference voltage and applied to the non-inverting input (corresponding to pin 3) of comparator U1B, thereby raising the voltage value of the reference signal.

[0105] The inverting input (pin 2) of comparator U1B is connected to the output (pin 7) of amplifier U1A via resistor R5, and is used to receive the voltage signal after the temperature signal is amplified.

[0106] The inverting input (pin 2) of comparator U1B is also connected to the output (pin 1) of comparator U1B via a second capacitor C2 and a ninth resistor R9 connected in series.

[0107] The output terminal of comparator U1B (corresponding to pin 1) is connected to the signal input terminal of driver circuit 200.

[0108] Comparator U1B compares the input voltage signal with a reference signal. When the voltage signal at the inverting input (corresponding to pin 2) is higher than the reference signal at the non-inverting input (corresponding to pin 3), comparator U1B outputs a low-level control signal.

[0109] When the voltage signal at the inverting input (corresponding to pin 2) is lower than the reference signal at the non-inverting input (corresponding to pin 3), the comparator U1B outputs a high-level control signal.

[0110] In some embodiments, the driving circuit 200 includes at least a second MOSFET Q2 and a third MOSFET Q3, wherein the second MOSFET Q2 is selected as an N-channel MOSFET and the third MOSFET Q3 is selected as a P-channel MOSFET, both of which have the function of switching;

[0111] Specifically, the gate of the second MOSFET Q2 is connected to one end of the tenth resistor R10, the other end of the tenth resistor R10 is connected to the cathode of the first diode D1, and the anode of the first diode D1 is connected to the output terminal (corresponding to pin 1) of the comparator U1B.

[0112] The drain of the second MOSFET Q2 is connected to the +12V power supply terminal (corresponding to +12V) through the twelfth resistor R12.

[0113] The gate of the third MOSFET Q3 is connected to the drain of the second MOSFET Q2.

[0114] The source of the third MOSFET Q3 is connected to the +12V power supply terminal (corresponding to +12V).

[0115] The drain of the third MOSFET Q3 is connected to one end of the load (corresponding to pin 1 of FAN1).

[0116] The source of the second MOSFET Q2 and the other end of the load (corresponding to pin 2 of FAN1) are connected to the common terminal respectively.

[0117] Specifically, the "12V" voltage is divided by the first resistor R1 and the thermistor RT1, and then the divided voltage is input to pins 5 and 6 of amplifier U1A through the second resistor R2 and the third resistor R3 respectively for amplification. After being amplified by the fourth resistor R4, it is output from pin 7 of amplifier U1A to comparator U1B.

[0118] The amplified voltage signal is output from pin 7 of amplifier U1A, sent to pin 2 of comparator U1B via the fifth resistor R5, and compared with the reference signal at pin 3 of comparator U1B.

[0119] Since the voltage signal at pin 3 of comparator U1B is divided by resistors R6 and R7 to process the "12V" voltage, the voltage at pin 3 of comparator U1B is 6V (reference signal) at this time.

[0120] When the voltage at pin 2 of comparator U1B is lower than 6V, pin 1 of comparator U1B will output a high level.

[0121] When the voltage at pin 2 of comparator U1B is higher than 6V, pin 1 of comparator U1B will output a low level.

[0122] Due to the characteristic that the resistance of an NTC decreases with increasing temperature, when the temperature of the temperature control circuit reaches 60℃, and the thermistor RT1 = 2.6K, the voltage across amplifier U1A is: 12V * RT1 / (first resistor R1 + thermistor RT1) = 12 * 2.6 / (100 + 2.6) = 0.04V. Therefore, the voltage at pin 7 of amplifier U1A is 0.04 * 150 = 6V.

[0123] Therefore, when the temperature of the first temperature signal is greater than 60℃, the voltage at pin 7 of amplifier U1A will be less than 6V.

[0124] The voltage at pin 2 of comparator U1B is lower than the voltage at pin 3 of comparator U1B. Therefore, pin 1 of comparator U1B outputs a high-level control signal, which is sent to the gate of the second MOSFET Q2 through the first diode D1 and the tenth resistor R10.

[0125] When pin 1 of comparator U1B is high, the high-level control signal passes through the first diode D1, the tenth resistor R10, the eleventh resistor R11, the second MOSFET Q2, the twelfth resistor R12, the third MOSFET Q3, and the second diode D2 to control the fan FAN1 to rotate.

[0126] The temperature of the temperature control circuit drops accordingly. When the temperature drops below 60℃, the fan FAN1 will stop rotating. That is, the fan FAN1 turns on / off for a very short time, which will cause the fan to frequently turn on and off and cause damage.

[0127] The drive signal for the first MOSFET Q1 comes from the output level of pin 1 of comparator U1B. When pin 1 of comparator U1B is high, the fan starts working, the gate voltage of the first MOSFET Q1 is high, and it is controlled to conduct.

[0128] At this point, decreasing the upper bias voltage divider resistor at pin 3 of comparator U1B, relative to increasing the lower bias voltage divider resistor, causes the voltage at pin 3 of comparator U1B to increase, meaning the reference voltage increases.

[0129] When the temperature of the second temperature signal drops to around 40°C, the voltage at pin 2 of comparator U1B is higher than the voltage at pin 3 of comparator U1B, and then fan FAN1 stops rotating.

[0130] When the first MOSFET Q1 is turned off, the reference 3 of comparator U1B returns to its original setting.

[0131] That is, when the temperature rises again (greater than the first temperature signal) and triggers the operation of fan FAN1, the first MOSFET Q1 is turned on again, and the hysteresis circuit plays a role again. When the temperature value drops from the first temperature to the second temperature, fan FAN1 will be triggered, thereby reducing the frequency of fan FAN1 on / off, which can extend the on / off life of fan FAN1 and improve the performance of the product.

[0132] When the temperature reaches 60℃, fan FAN1 starts to rotate;

[0133] When the temperature drops to 40℃, the fan FAN1 stops rotating, effectively protecting the product from overheating damage and solving the problem of shortened product lifespan caused by frequent on / off switching of the fan FAN1.

[0134] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A temperature control circuit, characterized in that, have: A signal control circuit, which is disposed within the temperature control circuit, is used to acquire the temperature signal of the load and output a control signal according to the current temperature signal. The drive circuit has its power input terminal connected to the power supply terminal to receive the drive voltage. The signal input terminal of the driving circuit is connected to the output terminal of the signal control circuit, and is used to receive the control signal, which is used to control the on / off state of the driving circuit; wherein, The signal control circuit includes at least an NTC detection module, an amplification module, a comparison module, and a hysteresis circuit. The NTC detection module is used to detect the temperature signal of the load. The input terminal of the amplification module is connected to the output terminal of the NTC detection module, and is used to receive the temperature signal. One input terminal of the comparison module is connected to the reference voltage terminal for receiving the reference signal. The other input terminal of the comparison module is connected to the output terminal of the amplification module, and is used to receive the temperature signal amplified by the amplification module. The output terminal of the comparison module is connected to the signal input terminal of the drive circuit. The first terminal of the hysteresis circuit is connected to the output terminal of the comparator module. The second terminal of the hysteresis circuit is connected to the reference voltage terminal. The third terminal of the hysteresis circuit is connected to one input terminal of the comparison module. The hysteresis circuit is used to change the voltage value of the reference signal to adjust the level of the control signal output by the comparison module.

2. The temperature control circuit according to claim 1, characterized in that, The hysteresis circuit includes a first MOSFET and an eighth resistor. The gate of the first MOS transistor is connected to the output terminal of the comparator module. The drain of the first MOSFET is connected to the reference voltage terminal. The source of the first MOS transistor is connected to one end of the eighth resistor. The other end of the eighth resistor is connected to one input terminal of the comparison module.

3. The temperature control circuit according to claim 2, characterized in that, It also includes a voltage divider module, the first terminal of which is connected to the reference voltage terminal. The second terminal of the voltage divider module is connected to one input terminal of the comparator module. The third terminal of the voltage divider module is connected to the common terminal.

4. The temperature control circuit according to claim 3, characterized in that, The voltage divider module includes a sixth resistor and a seventh resistor connected in series. One end of the sixth resistor is coupled to the reference voltage terminal. The other end of the sixth resistor and one end of the seventh resistor are connected to an input terminal of the comparison module. The other end of the seventh resistor is connected to the common terminal.

5. The temperature control circuit according to claim 4, characterized in that, The NTC detection module includes a first resistor and a thermistor connected in series. One end of the first resistor and one end of the thermistor are connected to an input terminal of the amplification module. The other end of the first resistor is connected to the 12V power supply. The other end of the thermistor is connected to the other input terminal and the common terminal of the amplification module, respectively.

6. The temperature control circuit according to claim 5, characterized in that, The amplification module includes at least one amplifier. The non-inverting input of the amplifier is connected to one end of the first resistor and one end of the thermistor via a second resistor. The inverting input of the amplifier is connected to the other end of the thermistor via a third resistor. The output of the amplifier is connected to the other input of the comparator module.

7. The temperature control circuit according to claim 6, characterized in that, The comparison module includes at least a comparator. The non-inverting input of the comparator is connected to the connection terminals of the sixth and seventh resistors. The non-inverting input of the comparator is also connected to the other end of the eighth resistor. The inverting input of the comparator is connected to the output of the amplifier via a fifth resistor. The output of the comparator is connected to the signal input of the drive circuit.

8. The temperature control circuit according to claim 7, characterized in that, The driving circuit includes at least a second MOSFET and a third MOSFET. The gate of the second MOSFET is connected to the output of the comparator via the first diode and the tenth resistor. The drain of the second MOSFET is connected to the +12V power supply terminal through the twelfth resistor. The gate of the third MOS transistor is connected to the drain of the second MOS transistor. The source of the third MOSFET is connected to the +12V power supply terminal. The drain of the third MOS transistor is connected to one end of the load. The source of the second MOS transistor and the other end of the load are respectively connected to the common terminal.

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