Fan control circuit

Abstract

This application provides a fan control circuit, comprising: a power supply control module connected to the fan's power supply terminal, used to provide power voltage to the fan in response to a power supply signal; and a fan control module connected to the fan's control terminal, used to input control signals to the fan in response to a drive signal. The power supply control module includes an isolating switch unit and a current-limiting switch unit. The isolating switch unit controls the current-limiting switch unit to conduct in response to the power supply signal, and the current-limiting switch unit disconnects when the current exceeds a set threshold. This application isolates the high-voltage power circuit from the low-voltage control circuit, improving the safety of the fan control circuit. Furthermore, it can automatically disconnect the circuit in case of a short circuit or overload fault in the fan's internal circuitry, thereby helping to prevent damage to the fan control circuit.

Description

Technical Field

[0001] This application relates to the field of heat dissipation technology, specifically to a fan control circuit. Background Technology

[0002] Currently, there are many conversion stages in the power system (such as DC-DC voltage conversion and DC-AC voltage conversion). During the conversion stages, most of the electrical energy loss is dissipated in the form of heat, which leads to the phenomenon of rising power system temperature. The rise in temperature affects system stability and component lifespan. Therefore, it is usually necessary to use fans to form convection heat dissipation to transfer the dissipated heat outside the system.

[0003] In related technologies, due to the limitations of high and low voltage, it is often necessary to isolate and control fans in some scenarios with high safety requirements. However, currently, relays are usually used to isolate and control the power supply of fans, but relays usually cannot provide timely protection when the fan current is short-circuited. Utility Model Content

[0004] This application provides a fan control circuit designed to solve the above-mentioned technical problems.

[0005] In a first aspect, this application provides a fan control circuit, including:

[0006] The power supply control module is connected to the power supply terminal of the fan and is used to provide power voltage to the fan in response to the power supply signal.

[0007] The fan control module is connected to the control terminal of the fan and is used to input control signals to the fan in response to the drive signal.

[0008] The power supply control module includes an isolating switch unit and a current limiting switch unit. The isolating switch unit responds to the power supply signal to control the current limiting switch unit to turn on, and the current limiting switch unit turns off when the current of the current limiting switch unit exceeds a set threshold.

[0009] In some embodiments, the disconnecting switch unit includes a first resistor, a second resistor, and a first optocoupler;

[0010] The first end of the first resistor is connected to the first power supply voltage, and the second end of the first resistor is connected to the positive terminal of the first optocoupler.

[0011] The first end of the second resistor is connected to the second power supply voltage, and the second end of the second resistor is connected to the collector of the first optocoupler.

[0012] The negative terminal of the first optocoupler is connected to the power supply signal, and the emitter of the first optocoupler is connected to the current limiting switch unit.

[0013] In some embodiments, the current limiting switch unit includes a current limiting protection switch and a current limiting resistor. The current limiting protection switch has an enable terminal, an input terminal, an output terminal, a current limiting terminal, and a ground terminal.

[0014] The enable terminal of the current limiting protection switch is connected to the emitter of the first optocoupler, the input terminal of the current limiting protection switch is connected to the second power supply voltage, the output terminal of the current limiting protection switch is connected to the power supply terminal of the fan, and the ground terminal of the current limiting protection switch is grounded.

[0015] The first end of the current-limiting resistor is connected to the current-limiting terminal of the current-limiting protection switch, and the second end of the current-limiting resistor is grounded.

[0016] In some embodiments, the current limiting switch unit further includes a first Zener diode, a first capacitor, and a third resistor;

[0017] The negative terminal of the first Zener diode is connected to the enable terminal of the current limiting protection switch, and the positive terminal of the first Zener diode is grounded.

[0018] The first terminal of the first capacitor is connected to the enable terminal of the current limiting protection switch, and the second terminal of the first capacitor is grounded.

[0019] The first end of the third resistor is connected to the enable terminal of the current limiting protection switch, and the second end of the third resistor is grounded.

[0020] In some embodiments, the current limiting switch unit further includes a second capacitor, a third capacitor, and a fourth capacitor;

[0021] The first terminal of the second capacitor is connected to the input terminal of the current limiting protection switch, and the second terminal of the second capacitor is grounded.

[0022] The first terminal of the third capacitor is connected to the input terminal of the current limiting protection switch, and the second terminal of the fourth capacitor is grounded.

[0023] The first terminal of the fourth capacitor is connected to the input terminal of the current limiting protection switch, and the second terminal of the fourth capacitor is grounded.

[0024] In some embodiments, the current limiting switch unit further includes a fifth capacitor, and the current limiting protection switch also has a start terminal;

[0025] The first terminal of the fifth capacitor is connected to the start terminal of the current limiting protection switch, and the second terminal of the fifth capacitor is grounded.

[0026] In some embodiments, the current limiting switch unit further includes a sixth capacitor, a seventh capacitor, and a first diode;

[0027] The first terminal of the sixth capacitor is connected to the output terminal of the current limiting protection switch, and the second terminal of the sixth capacitor is grounded.

[0028] The first terminal of the seventh capacitor is connected to the output terminal of the current limiting protection switch, and the second terminal of the seventh capacitor is grounded.

[0029] The negative terminal of the first diode is connected to the output terminal of the current limiting protection switch, and the positive terminal of the first diode is grounded.

[0030] In some embodiments, the fan control module includes a second optocoupler;

[0031] The positive terminal of the second optocoupler is connected to the first power supply voltage, and the negative terminal of the second optocoupler is connected to the drive signal.

[0032] The collector of the second optocoupler is connected to the second power supply voltage, the emitter of the second optocoupler is grounded, and the output terminal of the second optocoupler is connected to the control terminal of the fan.

[0033] In some embodiments, the fan control module further includes a first transistor, a fourth resistor, and a second Zener diode;

[0034] The first end of the fourth resistor is connected to the second power supply voltage, and the second end of the fourth resistor is connected to the collector of the first transistor.

[0035] The negative terminal of the second Zener diode is connected to the collector of the first transistor, and the positive terminal of the second Zener diode is grounded.

[0036] The base of the first transistor is connected to the output terminal of the second optocoupler, and the emitter of the first transistor is grounded.

[0037] In some embodiments, the fan control module further includes a fifth resistor, a sixth resistor, and an eighth capacitor;

[0038] The first terminal of the fifth resistor is connected to the base of the first transistor, and the second terminal of the fifth resistor is grounded.

[0039] The first end of the sixth resistor is connected to the collector of the first transistor, the second end of the sixth resistor is connected to the first end of the eighth capacitor, and the second end of the eighth capacitor is grounded.

[0040] In this embodiment, the isolating switch unit can output an enable signal for the voltage domain corresponding to the second supply voltage based on the first supply voltage and the supply signal. This enables the isolating switch unit to control the current limiting switch unit to conduct in response to the supply signal. Simultaneously, the current limiting switch unit is connected to the second supply voltage. Therefore, after the current limiting switch unit is turned on, it can output the power supply voltage corresponding to the voltage domain of the second supply voltage. In this way, the isolating switch unit achieves isolation between the voltage domain corresponding to the first supply voltage and the voltage domain corresponding to the second supply voltage. This not only ensures stable control of the power supply voltage but also isolates the power circuit in the high-voltage domain from the control circuit in the low-voltage domain, improving the safety of the fan control circuit. Furthermore, when the current of the current limiting switch unit exceeds a set threshold, the current limiting switch unit can automatically disconnect. Therefore, in the event of a short circuit or overload fault in the internal circuit of the fan, the circuit is automatically cut off, thereby preventing damage to the isolating switch unit, the current limiting switch unit, and the power supply corresponding to the second supply voltage. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0042] Figure 1 A schematic diagram of a fan control circuit in an embodiment of this application is shown;

[0043] Figure 2 Another schematic diagram of the fan control circuit in an embodiment of this application is shown;

[0044] Figure 3 Another schematic diagram of the fan control circuit in an embodiment of this application is shown;

[0045] Figure 4 Another schematic diagram of the fan control circuit in an embodiment of this application is shown;

[0046] Figure 5 Another schematic diagram of the fan control circuit in an embodiment of this application is shown;

[0047] Figure 6 Another schematic diagram of the fan control circuit in an embodiment of this application is shown;

[0048] Figure 7 Another schematic diagram of the fan control circuit in an embodiment of this application is shown;

[0049] Figure 8 Another schematic diagram of the fan control circuit in an embodiment of this application is shown;

[0050] Figure 9 Another schematic diagram of the fan control circuit in an embodiment of this application is shown;

[0051] Figure 10 Another schematic diagram of the fan control circuit in an embodiment of this application is shown;

[0052] Among them, there are 100 fan control circuits, 200 fans, 10 power supply control modules, 11 isolating switch units, 12 current limiting switch units, and 20 fan control modules;

[0053] Power supply signal POWER, power supply voltage FAN_POWER, drive signal PWM, control signal FAN_POWER, first power supply voltage VDD1, second power supply voltage VDD2;

[0054] First optocoupler O1, first resistor R1, second resistor R2, third resistor R3, fourth resistor R4, fifth resistor R5, sixth resistor R6, seventh resistor R7, eighth resistor R8, current limiting protection switch S0, current limiting resistor R0, first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4, fifth capacitor C5, sixth capacitor C6, seventh capacitor C7, eighth capacitor C8, ninth capacitor C9, tenth capacitor C10, first Zener diode Z1, second Zener diode Z2, first diode D1, first transistor Q1, second optocoupler O2. Detailed Implementation

[0055] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0056] In the description of this utility model, the term "exemplary" is used to mean "serving as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to implement and use this utility model. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this utility model can be implemented without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid obscuring the description of this utility model with unnecessary detail. Therefore, this utility model is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0057] This application provides a fan control circuit, which will be described in detail below.

[0058] First, refer to Figure 1 , Figure 1 A schematic diagram of a fan control circuit 100 in an embodiment of this application is shown, wherein the fan control circuit 100 includes a power supply control module 10 and a fan control module 20.

[0059] Specifically, the power supply control module 10 is connected to the power supply terminal of the fan 200. The power supply control module 10 can also be connected to a main control unit (e.g., a microcontroller). The main control unit can send a power supply signal POWER to the power supply control module 10, thus the power supply control module 10 can provide a power supply voltage FAN_POWER to the fan 200 in response to the POWER signal. For example, taking the power supply control module 10 outputting the power supply voltage FAN_POWER upon receiving a high-level signal as an example, the power supply control module 10 can include a high-level on switch (e.g., a PMOS transistor). The main control unit can send a 3.3V high-level signal to the power supply control module 10, and the power supply control module 10 can provide a 12V power supply voltage FAN_POWER to the fan 200 in response to the high-level signal. For example, taking the power supply control module 10 outputting power supply voltage FAN_POWER upon receiving a low-level signal as an example, the power supply control module 10 may include a low-level conducting switch (e.g., an NMOS transistor), and the main control unit may send a low-level signal to the power supply control module 10. In response to the low-level signal, the power supply control module 10 may provide a 12V power supply voltage FAN_POWER to the fan 200.

[0060] In some embodiments of this application, the power supply signal POWER is a low-voltage signal, and the power supply voltage FAN_POWER is a high-voltage signal. For example, the power supply signal POWER is a 3.3V voltage signal, and the power supply voltage FAN_POWER is a 12V voltage signal, so that the fan control circuit 100 can use the 3.3V voltage signal POWER to output the 12V voltage signal FAN_POWER, thereby helping to reduce the power consumption of the fan control circuit 100.

[0061] The fan control module 20 is connected to the control terminal of the fan 200. The fan control module 20 can be connected to the main control unit (e.g., a microcontroller). The main control unit can send a drive signal PWM (e.g., a PWM signal) to the fan control module 20. Therefore, the power supply control module 10 can respond to the drive signal PWM and provide a control signal FAN_POWER (e.g., a PWM signal) to the fan 200, so that the fan 200 ultimately operates under the power supply voltage FAN_POWER and the control signal FAN_POWER, and dissipates heat from the target device (e.g., the transformer winding of a power system, a DC-DC converter, or an inverter).

[0062] In some embodiments of this application, the drive signal PWM is a low-voltage domain signal, and the control signal FAN_POWER is a high-voltage domain signal. For example, the drive signal PWM is a 3.3V voltage domain signal, while the control signal FAN_POWER is a 12V voltage domain signal, so that the fan control circuit 100 can use the 3.3V voltage domain drive signal PWM to output the 12V voltage domain control signal FAN_POWER, thereby reducing the power consumption of the fan control circuit 100.

[0063] In the embodiments of this application, see Figure 1 The power supply control module 10 includes an isolating switch unit 11 and a current limiting switch unit 12. The isolating switch unit 11 is connected to a first power supply voltage VDD1 (e.g., 3.3V) and a second power supply voltage VDD2 (e.g., 12V). The isolating switch unit 11 can output an enable signal for the voltage domain corresponding to the second power supply voltage VDD2 based on the first power supply voltage VDD1 and the power supply signal POWER. This enables the isolating switch unit 11 to control the current limiting switch unit 12 to turn on in response to the power supply signal POWER. Since the current limiting switch unit 12 is connected to the second power supply voltage VDD2, it can output the power supply voltage FAN_POWER corresponding to the voltage domain of the second power supply voltage VDD2 after it is turned on. In this way, the isolating switch unit 11 realizes the isolation between the voltage domain corresponding to the first power supply voltage VDD1 and the voltage domain corresponding to the second power supply voltage VDD2. This not only ensures the stable control of the power supply voltage FAN_POWER, but also isolates the power circuit in the high voltage domain from the control circuit in the low voltage domain, thereby improving the safety of the fan control circuit 100. Meanwhile, when the current of the current limiting switch unit 12 exceeds the set threshold, the current limiting switch unit 12 can automatically disconnect. Therefore, when a short circuit or overload fault occurs in the internal circuit of the fan 200, the circuit is automatically cut off, thereby avoiding damage to the isolation switch unit 11, the current limiting switch unit 12, and the power supply corresponding to the second power supply voltage VDD2.

[0064] In some embodiments of this application, see Figure 2 , Figure 2Another schematic diagram of the fan control circuit 100 in an embodiment of this application is shown, wherein the isolating switch unit 11 includes a first resistor R1, a second resistor R2, and a first optocoupler O1; the first end of the first resistor R1 is connected to a first power supply voltage VDD1, and the second end of the first resistor R1 is connected to the positive terminal of the first optocoupler O1; the first end of the second resistor R2 is connected to a second power supply voltage VDD2, and the second end of the second resistor R2 is connected to the collector of the first optocoupler O1; the negative terminal of the first optocoupler O1 is connected to the power supply signal POWER, and the emitter of the first optocoupler O1 is connected to the current limiting switch unit.

[0065] It should be noted that the first resistor R1 is the current-limiting resistor R0 of the positive terminal of the first optocoupler O1, and the second resistor R2 is the current-limiting resistor R0 of the collector of the first optocoupler O1. This is to limit the current input to the first optocoupler O1 through the first resistor R1 and the second resistor R2, preventing damage to the first optocoupler O1 due to excessive current. Simultaneously, when the power supply signal POWER is low, the photodiode connected between the positive and negative terminals of the first optocoupler O1 emits light, and the photodetector connected between the collector and emitter of the first optocoupler O1 conducts light. Therefore, the emitter of the first optocoupler O1 can output the power supply voltage FAN_POWER for the fan 200. Conversely, when the power supply signal POWER is high, the photodiode connected between the positive and negative terminals of the first optocoupler O1 stops emitting light, and the photodetector connected between the collector and emitter of the first optocoupler O1 is cut off. Therefore, the emitter of the first optocoupler O1 stops outputting the power supply voltage FAN_POWER.

[0066] As can be seen, since the first optocoupler O1 not only isolates the first power supply voltage VDD1 and the second power supply voltage VDD2, but also outputs the power supply voltage FAN_POWER in the voltage domain corresponding to the second power supply voltage VDD2, it realizes the isolation between the power supply signal POWER input and the power supply voltage FAN_POWER output, so as to improve the safety of the fan control circuit 100.

[0067] In some embodiments of this application, see Figure 3 , Figure 3Another schematic diagram of the fan control circuit 100 in this embodiment is shown, wherein the current limiting switch unit 12 includes a current limiting protection switch S0 and a current limiting resistor R0. The current limiting protection switch S0 has an enable terminal EN, an input terminal VIN, an output terminal SOURCE, a current limiting terminal ILIMIT, and a ground terminal GND. The enable terminal EN of the current limiting protection switch S0 is connected to the emitter of the first optocoupler O1. The input terminal VIN of the current limiting protection switch S0 is connected to the second power supply voltage VDD2. The output terminal SOURCE of the current limiting protection switch S0 is connected to the power supply terminal of the fan 200. The ground terminal GND of the current limiting protection switch S0 is grounded. The first end of the current limiting resistor R0 is connected to the current limiting terminal ILIMIT of the current limiting protection switch S0, and the second end of the current limiting resistor R0 is grounded.

[0068] It should be noted that after the power supply signal POWER is low and the emitter of the first optocoupler O1 outputs a voltage signal, the enable terminal EN of the current limiting protection switch S0 receives the voltage signal and opens the path between its input terminal VIN and output terminal SOURCE. Therefore, the output terminal SOURCE of the current limiting protection switch S0 can output the power supply voltage FAN_POWER corresponding to the voltage domain of the second power supply voltage VDD2. At the same time, the current limiting resistor R0 connected to the current limiting terminal ILIMIT of the current limiting protection switch S0 will generate a current corresponding to the set threshold value. If the current at the output terminal SOURCE of the current limiting protection switch S0 exceeds the current flowing through the current limiting resistor R0, the current limiting protection switch S0 will automatically turn off the path between the input terminal VIN and the output terminal SOURCE, so that the current limiting protection switch S0 stops outputting the power supply voltage FAN_POWER and realizes current limiting protection.

[0069] In some embodiments of this application, see Figure 4 , Figure 4 The diagram shows another schematic of the fan control circuit 100 in an embodiment of this application, wherein the current limiting switch unit 12 further includes a first Zener diode Z1, a first capacitor C1, and a third resistor R3; the cathode of the first Zener diode Z1 is connected to the enable terminal EN of the current limiting protection switch S0, and the anode of the first Zener diode Z1 is grounded; the first terminal of the first capacitor C1 is connected to the enable terminal EN of the current limiting protection switch S0, and the second terminal of the first capacitor C1 is grounded; the first terminal of the third resistor R3 is connected to the enable terminal EN of the current limiting protection switch S0, and the second terminal of the third resistor R3 is grounded.

[0070] Specifically, the first Zener diode Z1 and the third resistor R3 form an overvoltage clamping circuit for the enable terminal EN of the current limiting protection switch S0, preventing damage caused by excessively high voltage at the enable terminal EN of the current limiting protection switch S0; the first capacitor C1 forms a filter capacitor for the enable terminal EN of the current limiting protection switch S0, preventing the current limiting protection switch S0 from being falsely triggered by pulse voltage and outputting the power supply voltage FAN_POWER.

[0071] In some embodiments of this application, see Figure 5 , Figure 5 This illustration shows another schematic diagram of the fan control circuit 100 in an embodiment of this application. The current limiting switch unit 12 further includes a second capacitor C2, a third capacitor C3, and a fourth capacitor C4. The first terminal of the second capacitor C2 is connected to the input terminal VIN of the current limiting protection switch S0, and the second terminal of the second capacitor C2 is grounded. The first terminal of the third capacitor C3 is connected to the input terminal VIN of the current limiting protection switch S0, and the second terminal of the fourth capacitor C4 is grounded. Specifically, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 form a filter and energy storage capacitor for the input terminal VIN of the current limiting protection switch S0. The second capacitor C2, the third capacitor C3, and the fourth capacitor C4 can filter the second power supply voltage VDD2 of the input current limiting protection switch S0, so that the current limiting protection switch S0 outputs a high-quality power supply voltage FAN_POWER with smaller voltage ripple.

[0072] In some embodiments of this application, see Figure 6 , Figure 6 Another schematic diagram of the fan control circuit 100 in an embodiment of this application is shown, wherein the current limiting switch unit 12 further includes a fifth capacitor C5, and the current limiting protection switch S0 also has a start terminal DV / DT; the first terminal of the fifth capacitor C5 is connected to the start terminal DV / DT of the current limiting protection switch S0, and the second terminal of the fifth capacitor C5 is grounded.

[0073] It should be noted that after the current limiting switch unit 12 starts up, the fifth capacitor C5 will be fully charged before the current limiting switch unit 12 will output the power supply voltage FAN_POWER. Based on the charging time constant of the capacitor, it can be known that the time for the fifth capacitor C5 to be fully charged can realize the delay start current limiting protection switch S0, thereby avoiding excessive current surges in the fan control circuit 100 during startup, thus protecting the electronic components in the fan control circuit 100 from damage.

[0074] In some embodiments of this application, see Figure 7 , Figure 7The diagram shows another schematic of the fan control circuit 100 in an embodiment of this application, wherein the current limiting switch unit 12 further includes a sixth capacitor C6, a seventh capacitor C7, and a first diode D1; the first terminal of the sixth capacitor C6 is connected to the output terminal SOURCE of the current limiting protection switch S0, and the second terminal of the sixth capacitor C6 is grounded; the first terminal of the seventh capacitor C7 is connected to the output terminal SOURCE of the current limiting protection switch S0, and the second terminal of the seventh capacitor C7 is grounded; the cathode of the first diode D1 is connected to the output terminal SOURCE of the current limiting protection switch S0, and the anode of the first diode D1 is grounded.

[0075] It should be noted that the sixth capacitor C6 and the seventh capacitor C7 are filter and energy storage capacitors for the output terminal SOURCE of the current limiting protection switch S0. They can filter the power supply voltage FAN_POWER output from the input current limiting protection switch S0 to produce a high-quality power supply voltage FAN_POWER with smaller voltage ripple. The first diode D1 is the freewheeling diode for the output terminal SOURCE of the current limiting protection switch S0, which helps to prevent the reverse electromotive force after the fan 200 is turned off from damaging the circuit.

[0076] In some embodiments of this application, see Figure 8 , Figure 8 Another schematic diagram of the fan control circuit 100 in this embodiment is shown, wherein the fan control module 20 includes a second optocoupler O2; the positive terminal ANODE of the second optocoupler O2 is connected to the first power supply voltage VDD1, the negative terminal CATHODE of the second optocoupler O2 is connected to the drive signal PWM; the collector VCC of the second optocoupler O2 is connected to the second power supply voltage VDD2, the emitter VEE of the second optocoupler O2 is grounded, and the output terminal VOUT of the second optocoupler O2 is connected to the control terminal of the fan 200.

[0077] Specifically, when the drive signal PWM is low, the photodiode connected between the positive terminal ANODE and the negative terminal CATHODE of the second optocoupler O2 emits light, and the photodetector connected between the collector VCC and the emitter VEE of the second optocoupler O2 is turned on by the light. Therefore, the output terminal VOUT of the second optocoupler O2 can output a high-level signal. Conversely, when the drive signal PWM is high, the photodiode connected between the positive terminal ANODE and the negative terminal CATHODE of the second optocoupler O2 stops emitting light, and the photodetector connected between the collector VCC and the emitter VEE of the second optocoupler O2 is turned off. Therefore, the output terminal VOUT of the second optocoupler O2 can output a low-level signal. It can be seen that the second optocoupler O2 isolates the drive signal PWM from the control signal FAN_POWER, thereby improving the safety of the fan control circuit 100.

[0078] In some embodiments of this application, see further reference. Figure 8The fan control module 20 also includes a first transistor Q1, a fourth resistor R4, and a second Zener diode Z2; the first terminal of the fourth resistor R4 is connected to the second power supply voltage VDD2, and the second terminal of the fourth resistor R4 is connected to the collector of the first transistor Q1; the negative terminal CATHODE of the second Zener diode Z2 is connected to the collector of the first transistor Q1, and the positive terminal of the second Zener diode Z2 is grounded; the base of the first transistor Q1 is connected to the output terminal VOUT of the second optocoupler O2, and the emitter of the first transistor Q1 is grounded.

[0079] It should be noted that the fourth resistor R4 and the second Zener diode Z2 form a limiting circuit. This limiting circuit can control the voltage of the control signal FAN_POWER within the required voltage range, ensuring that the voltage of the control signal FAN_POWER meets the fan control requirements. Simultaneously, when the drive signal PWM is low, the output terminal VOUT of the second optocoupler O2 outputs a high-level signal, the first transistor Q1 is turned on, and the collector voltage of the first transistor Q1 is pulled down to ground. At this time, the control signal FAN_POWER is low. Conversely, when the drive signal PWM is high, the output terminal VOUT of the second optocoupler O2 can output a low-level signal, the first transistor Q1 is turned off, and the collector voltage of the first transistor Q1 is pulled up to the second supply voltage VDD2. At this time, the control signal FAN_POWER is high. The fan speed 200 can be controlled by switching between high and low levels of the control signal FAN_POWER and adjusting the signal duty cycle.

[0080] In some embodiments of this application, see Figure 9 , Figure 9 Another schematic diagram of the fan control circuit 100 in an embodiment of this application is shown, wherein the fan control module 20 further includes a fifth resistor R5, a sixth resistor R6, and an eighth capacitor C8; the first end of the fifth resistor R5 is connected to the base of the first transistor Q1, and the second end of the fifth resistor R5 is grounded; the first end of the sixth resistor R6 is connected to the collector of the first transistor Q1, and the second end of the sixth resistor R6 is connected to the first end of the eighth capacitor C8, and the second end of the eighth capacitor C8 is grounded.

[0081] It should be noted that the fifth resistor R5 can provide a bias voltage to the base of the first transistor Q1, ensuring the stability and reliability of the first transistor Q1 under different operating conditions. At the same time, since the switching frequency of the first transistor Q1 is relatively high, the sixth resistor R6 and the eighth capacitor C8 connected to the collector of the first transistor Q1 can control the output spike and rising edge of the signal FAN_POWER to adjust, thereby helping to reduce electromagnetic interference caused by voltage surges.

[0082] It is worth noting that the above description of the fan control circuit 100 is intended to clearly illustrate the implementation and verification process of this application. Those skilled in the art can also make equivalent modifications under the guidance of this application; for example, refer to... Figure 9 Furthermore, a base current-limiting resistor R0R8 can be set between the output terminal of the second optocoupler O2 and the base of the first transistor Q1, and a ninth capacitor C9 and a tenth capacitor C10 can be set to filter the second supply voltage VDD2. For example, in... Figure 8 In addition, in point 9, the second optocoupler O2 is a drive optocoupler that can meet the requirements of high-speed driving, but it is not limited to this. See also... Figure 10 , Figure 10 Another schematic diagram of the fan control circuit 100 in this embodiment is shown. In this embodiment, the second optocoupler O2 can also be a logic optocoupler that meets the requirements of high-speed driving. When the driving signal PWM is high, the second optocoupler O2 is turned off, and the pull-up resistor inside the second optocoupler O2 pulls the control signal FAN_POWER to a high level. Conversely, when the driving signal PWM is low, the second optocoupler O2 is turned on, and the transistor inside the second optocoupler O2 is turned on, pulling the control signal FAN_POWER to a low level, thereby realizing the high and low level output of the control signal FAN_POWER.

[0083] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the detailed descriptions of other embodiments above, which will not be repeated here.

[0084] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0085] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0086] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the utility model, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the present application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0087] The above provides a detailed description of a fan control circuit 100 provided in the embodiments of this application. Specific examples have been used to illustrate the principle and implementation of this utility model. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A fan control circuit, characterized in that, include: A power supply control module is connected to the power supply terminal of the fan, and the power supply control module is used to provide power voltage to the fan in response to a power supply signal; A fan control module is connected to the control terminal of the fan and is used to input a control signal to the fan in response to a drive signal. The power supply control module includes an isolating switch unit and a current limiting switch unit. The isolating switch unit controls the current limiting switch unit to turn on in response to the power supply signal, and the current limiting switch unit turns off when the current of the current limiting switch unit exceeds a set threshold.

2. The fan control circuit as described in claim 1, characterized in that, The isolating switch unit includes a first resistor, a second resistor, and a first optocoupler; The first end of the first resistor is connected to the first power supply voltage, and the second end of the first resistor is connected to the positive terminal of the first optocoupler. The first end of the second resistor is connected to the second power supply voltage, and the second end of the second resistor is connected to the collector of the first optocoupler; The negative terminal of the first optocoupler is connected to the power supply signal, and the emitter of the first optocoupler is connected to the current limiting switch unit.

3. The fan control circuit as described in claim 2, characterized in that, The current limiting switch unit includes a current limiting protection switch and a current limiting resistor. The current limiting protection switch has an enable terminal, an input terminal, an output terminal, a current limiting terminal, and a ground terminal. The enable terminal of the current limiting protection switch is connected to the emitter of the first optocoupler, the input terminal of the current limiting protection switch is connected to the second power supply voltage, the output terminal of the current limiting protection switch is connected to the power supply terminal of the fan, and the ground terminal of the current limiting protection switch is grounded. The first end of the current-limiting resistor is connected to the current-limiting terminal of the current-limiting protection switch, and the second end of the current-limiting resistor is grounded.

4. The fan control circuit as described in claim 3, characterized in that, The current limiting switch unit also includes a first Zener diode, a first capacitor, and a third resistor; The negative terminal of the first Zener diode is connected to the enable terminal of the current limiting protection switch, and the positive terminal of the first Zener diode is grounded. The first terminal of the first capacitor is connected to the enable terminal of the current limiting protection switch, and the second terminal of the first capacitor is grounded. The first end of the third resistor is connected to the enable terminal of the current limiting protection switch, and the second end of the third resistor is grounded.

5. The fan control circuit as described in claim 3, characterized in that, The current limiting switch unit also includes a second capacitor, a third capacitor, and a fourth capacitor; The first terminal of the second capacitor is connected to the input terminal of the current limiting protection switch, and the second terminal of the second capacitor is grounded. The first terminal of the third capacitor is connected to the input terminal of the current limiting protection switch, and the second terminal of the fourth capacitor is grounded. The first terminal of the fourth capacitor is connected to the input terminal of the current limiting protection switch, and the second terminal of the fourth capacitor is grounded.

6. The fan control circuit as described in claim 3, characterized in that, The current limiting switch unit also includes a fifth capacitor, and the current limiting protection switch also has a start terminal; The first terminal of the fifth capacitor is connected to the start terminal of the current limiting protection switch, and the second terminal of the fifth capacitor is grounded.

7. The fan control circuit as described in claim 3, characterized in that, The current limiting switch unit also includes a sixth capacitor, a seventh capacitor, and a first diode; The first terminal of the sixth capacitor is connected to the output terminal of the current limiting protection switch, and the second terminal of the sixth capacitor is grounded. The first terminal of the seventh capacitor is connected to the output terminal of the current limiting protection switch, and the second terminal of the seventh capacitor is grounded. The negative terminal of the first diode is connected to the output terminal of the current limiting protection switch, and the positive terminal of the first diode is grounded.

8. The fan control circuit as described in claim 1, characterized in that, The fan control module includes a second optocoupler; The positive terminal of the second optocoupler is connected to the first power supply voltage, and the negative terminal of the second optocoupler is connected to the drive signal; The collector of the second optocoupler is connected to the second power supply voltage, the emitter of the second optocoupler is grounded, and the output terminal of the second optocoupler is connected to the control terminal of the fan.

9. The fan control circuit as described in claim 8, characterized in that, The fan control module also includes a first transistor, a fourth resistor, and a second Zener diode; The first end of the fourth resistor is connected to the second power supply voltage, and the second end of the fourth resistor is connected to the collector of the first transistor. The negative terminal of the second Zener diode is connected to the collector of the first transistor, and the positive terminal of the second Zener diode is grounded. The base of the first transistor is connected to the output terminal of the second optocoupler, and the emitter of the first transistor is grounded.

10. The fan control circuit as described in claim 9, characterized in that, The fan control module also includes a fifth resistor, a sixth resistor, and an eighth capacitor; The first end of the fifth resistor is connected to the base of the first transistor, and the second end of the fifth resistor is grounded. The first end of the sixth resistor is connected to the collector of the first transistor, the second end of the sixth resistor is connected to the first end of the eighth capacitor, and the second end of the eighth capacitor is grounded.

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