Control circuit for controlling rotating speed of vehicle-mounted cooling fan

Abstract

The utility model relates to a vehicle-mounted cooling fan rotating speed control circuit which comprises a control module, a voltage-stabilizing power supply module and a rotating speed adjusting module, the power input end of the voltage-stabilizing power supply module is connected with a power source, and the power output end of the voltage-stabilizing power supply module is connected with a fan. A reference voltage signal output end of the control module is connected with an enable signal input end of the voltage-stabilizing power supply module, an adjusting voltage signal output end of the control module is connected with an enable signal input end of the rotating speed adjusting module, and a signal output end of the rotating speed adjusting module is connected with a feedback signal input end of the voltage-stabilizing power supply module. The control module changes the resistance value of the rotating speed adjusting module so that the voltage-stabilizing power supply module can output the corresponding power supply voltage, and then the rotating speed of the fan is adjusted. The two-wire fan with lower cost can be used, the problem of high cost of a three-wire or four-wire fan is avoided, and the electronic equipment can be quickly cooled in a high-temperature environment.

Description

Technical Field

[0001] The present application relates to the field of vehicle-mounted cooling fan speed control circuits, and in particular to a vehicle-mounted cooling fan speed control circuit. Background Art

[0002] As the integration of automotive electronic devices increases, the heat generated increases, and the heat dissipation faced by each integrated device becomes increasingly challenging. Conventional SOC cooling can no longer meet the extreme operating requirements of automotive manufacturers. Consequently, more and more automotive electronic devices are incorporating cooling fans to rapidly dissipate heat and meet these extreme operating temperature requirements. Because three-wire and four-wire fans feature PWM speed control, eliminating the need for additional regulation circuitry, these fans are relatively expensive, leading most customers to use two-wire fans. However, these second-stage fans lack the corresponding PWM speed control, resulting in inadequate cooling for the automotive electronics. Utility Model Content

[0003] In order to solve the problem that customers choose a two-stage fan due to cost but the two-stage fan lacks the corresponding PWM speed adjustment function, resulting in the inability to dissipate heat for vehicle-mounted electronic equipment in a timely manner, the present application provides a vehicle-mounted control cooling fan speed control circuit.

[0004] The present application provides a vehicle-mounted cooling fan speed control circuit that adopts the following technical solution:

[0005] A vehicle-mounted cooling fan speed control circuit includes a control module, a temperature detection module, a voltage-stabilized power supply module and a speed regulation module. The power input end of the voltage-stabilized power supply module is connected to the power supply, and the power output end of the voltage-stabilized power supply module is connected to the fan. The temperature detection module is used to obtain the device temperature of the vehicle-mounted electronic equipment. The temperature signal output end of the temperature detection module is connected to the temperature signal input end of the control module. The reference voltage signal output end of the control module is connected to the enable signal input end of the voltage-stabilized power supply module. The adjustment voltage signal output end of the control module is connected to the enable signal input end of the speed regulation module. The signal output end of the speed regulation module is connected to the feedback signal input end of the voltage-stabilized power supply module. When the temperature detection module detects that the device temperature exceeds a preset threshold, the control module changes the resistance value of the speed regulation module so that the voltage-stabilized power supply module outputs the corresponding supply voltage, thereby regulating the speed of the fan.

[0006] The above technical solution effectively solves the problem of two-wire fans lacking PWM speed control, which prevents them from providing timely cooling for onboard electronic devices. Its operating principle is that a temperature detection module acquires real-time temperature signals from onboard electronic devices. When the device temperature exceeds a preset threshold, the temperature detection module transmits the temperature signal to a control module. Based on the received temperature signal, the control module generates a reference voltage and a regulated voltage signal, which are sent to the voltage-stabilized power supply module and the speed regulation module, respectively. The speed regulation module adjusts the feedback signal by varying its resistance, thereby affecting the output voltage of the voltage-stabilized power supply module. The voltage-stabilized power supply module adjusts the supply voltage based on the feedback signal and ultimately controls the fan speed, enabling flexible fan speed adjustment under varying temperature conditions to effectively dissipate heat for onboard electronic devices. This system not only utilizes lower-cost two-wire fans, avoiding the high costs of three- or four-wire fans, but also ensures rapid cooling of electronic devices in high-temperature environments, thereby improving their reliability and service life.

[0007] Preferably, the voltage-stabilized power supply module includes an LDO chip, a VIN pin of the LDO chip is connected to a power supply, a VOUT pin of the LDO chip is connected to a fan, and the speed regulation module is connected between the VOUT pin of the LDO chip and the FB pin of the LDO chip.

[0008] By adopting this technical solution, the LDO chip can achieve a regulated power supply. The LDO chip can provide a stable voltage output to the fan at the power input, ensuring a stable voltage without fluctuations during fan operation, thereby improving the fan's operating stability. In addition, the speed regulation module is connected between the VOUT and FB pins of the LDO chip, enabling precise feedback regulation of the output voltage, effectively improving the fan's speed control accuracy.

[0009] Preferably, the speed regulation module includes a plurality of voltage dividing units and a resistor Ru arranged in parallel, the first end of the resistor Ru is connected to the VOUT pin of the LDO chip, the second end of the resistor Ru is connected to the first end of the voltage dividing unit, the second end of the voltage dividing unit is grounded, and the third end of the voltage dividing unit is connected to the adjustment voltage signal output end of the control module.

[0010] By adopting the above technical solution, the fan speed can be adjusted through multiple parallel-connected voltage divider units and resistor Ru. Resistor Ru is connected to the VOUT pin of the LDO chip and the voltage divider unit, and the third end of the voltage divider unit is connected to the regulated voltage signal output terminal of the control module. This structure can effectively adjust the voltage, thereby achieving precise control of the fan speed and improving the fan's heat dissipation effect.

[0011] Preferably, the voltage dividing unit includes at least a resistor Rd and a switch conduction element, the first end of the resistor Rd is connected to the second end of the resistor Ru, the second end of the resistor Rd is connected to the first conduction end of the switch conduction element, the second conduction end of the switch conduction element is grounded, the controlled end of the switch conduction element is connected to the regulated voltage signal output end of the control module, and the common node between the first end of the resistor Rd and the resistor Ru is connected to the FB pin of the LDO chip.

[0012] By adopting this technical solution, the resistor Rd in the voltage divider unit and the switch conduction element cooperate to achieve precise voltage distribution and regulation. The control module's regulated voltage signal controls the conduction state of resistor Rd through the switch conduction element, adjusting the resistance value and thus the voltage fed back to the FB pin of the LDO chip. This design enables rapid response to temperature changes, adjusting fan speed, and improving the responsiveness and accuracy of the fan speed control system.

[0013] Preferably, the switch conduction element is a MOS tube.

[0014] By adopting the above technical solution, the MOS tube can be used as a switch conduction element. Relying on the low on-resistance and high switching speed of the MOS tube, the on-off state of the resistor Rd can be quickly switched, thereby achieving fast and accurate control of the voltage division and improving the efficiency and control accuracy of the fan speed regulation.

[0015] Preferably, the MOS transistor is an NMOS transistor.

[0016] By adopting the above technical solution, NMOS tubes can be used as switch conduction elements. NMOS tubes have lower conduction voltage and efficient current control capability, which can reduce power consumption in the circuit and improve switching speed and reliability, thereby improving the efficiency and accuracy of fan speed control.

[0017] Preferably, the control module includes a SOC chip, and the SOC chip is provided with multiple GPIO ports, one of which serves as the reference voltage signal output end of the control module and is connected to the EN pin of the LDO chip, and the other GPIO ports serve as the adjustment voltage signal output end of the control module and are connected to the controlled end of the switch conduction element.

[0018] By adopting the above technical solution, the enable pin of the LDO chip can be controlled through the GPIO port of the SOC chip to achieve on-off control of the fan power supply. In addition, other GPIO ports can output regulated voltage signals to control the on-off state of the switch conductive element, thereby achieving precise adjustment of the fan speed, ensuring that the heat dissipation demand can respond to the temperature changes of the equipment in real time, and further improving the intelligence and automation level of the system.

[0019] Preferably, the SOC chip is provided with a core temperature self-detection unit.

[0020] By adopting the above technical solution, the internal temperature of the chip can be monitored in real time through the core temperature self-test unit integrated in the SOC chip, ensuring a rapid response when the chip temperature rises, adjusting the fan speed or other cooling measures, thereby improving the overall reliability and cooling efficiency of the system and preventing performance degradation or damage to the equipment due to overheating.

[0021] Preferably, a capacitor is connected between the VOUT pin of the LDO chip and the ground.

[0022] By adopting the above technical solution, a capacitor can be connected between the VOUT pin of the LDO chip and the ground. The capacitor can play a filtering role, reduce voltage fluctuations in the power supply output, and ensure that the fan operates under a stable power supply voltage, thereby improving the fan's service life and system stability.

[0023] Preferably, the temperature detection module includes at least one thermistor.

[0024] By adopting the above technical solution, the temperature of on-board electronic equipment can be monitored in real time through the thermistor in the temperature detection module. The resistance of the thermistor changes with the temperature, and the temperature signal can be accurately transmitted to the control module, thereby achieving precise control of the fan speed, avoiding overheating of the equipment, and improving the heat dissipation performance and safety of the system.

[0025] In summary, this application includes at least one of the following beneficial technical effects:

[0026] 1. This effectively addresses the issue of two-wire fans lacking PWM speed control, preventing them from providing timely cooling for onboard electronic devices. Its operating principle is that a temperature detection module acquires real-time temperature signals from onboard electronic devices. When the device temperature exceeds a preset threshold, the temperature detection module transmits the temperature signal to the control module. Based on the received temperature signal, the control module generates a reference voltage and a regulated voltage signal, which are sent to the voltage-stabilized power supply module and the speed control module, respectively. The speed control module adjusts the feedback signal by varying its resistance, thereby affecting the output voltage of the voltage-stabilized power supply module. The voltage-stabilized power supply module adjusts the supply voltage based on the feedback signal, ultimately controlling the fan speed. This allows the fan to flexibly adjust its speed under varying temperature conditions, effectively cooling the onboard electronic devices. This approach not only enables the use of lower-cost two-wire fans, avoiding the high costs of three- or four-wire fans, but also ensures rapid cooling of electronic devices in high-temperature environments, thereby improving their reliability and service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of a vehicle-mounted cooling fan speed control circuit according to an embodiment of the present application.

[0028] Figure 2 This is a partial circuit structure diagram of a vehicle-mounted cooling fan speed control circuit according to an embodiment of the present application.

[0029] Description of reference numerals:

[0030] 1. Control module; 2. Temperature detection module; 3. Voltage stabilization power supply module; 4. Speed ​​regulation module. DETAILED DESCRIPTION

[0031] The following is combined with Figure 1-2 This application is described in further detail.

[0032] like Figure 1 As shown, a vehicle-mounted cooling fan speed control circuit includes a control module 1, a temperature detection module 2, a voltage-stabilized power supply module 3 and a speed regulation module 4. The power input end of the voltage-stabilized power supply module 3 is connected to the power supply, and the power output end of the voltage-stabilized power supply module 3 is connected to the fan. The temperature detection module 2 is used to obtain the device temperature of the vehicle-mounted electronic equipment, the temperature signal output end of the temperature detection module 2 is connected to the temperature signal input end of the control module 1, the reference voltage signal output end of the control module 1 is connected to the enable signal input end of the voltage-stabilized power supply module 3, the adjustment voltage signal output end of the control module 1 is connected to the enable signal input end of the speed regulation module 4, and the signal output end of the speed regulation module 4 is connected to the feedback signal input end of the voltage-stabilized power supply module 3. When the temperature detection module 2 detects that the device temperature exceeds a preset threshold, the control module 1 changes the resistance value of the speed regulation module 4 so that the voltage-stabilized power supply module 3 outputs the corresponding supply voltage, thereby adjusting the speed of the fan.

[0033] In this embodiment, the vehicle-mounted cooling fan speed control circuit achieves precise fan speed regulation through the coordinated operation of a series of modules. Temperature detection module 2 is used to obtain the device temperature of the vehicle-mounted electronic device in real time. When the device temperature exceeds a preset threshold, temperature detection module 2 transmits the temperature signal to control module 1, which generates a reference voltage signal and an adjustment voltage signal based on the received temperature signal. The reference voltage signal is output to voltage-stabilized power supply module 3, which determines whether to power the fan based on the signal's status. The adjustment voltage signal acts on speed regulation module 4, which modulates the feedback signal by adjusting its internal resistance, thereby affecting the output voltage of voltage-stabilized power supply module 3 and achieving precise fan speed control. Through the coordinated operation of control module 1, the entire circuit can adjust the fan speed in real time according to the temperature of the vehicle-mounted electronic device. When the device temperature rises, timely heat dissipation is provided to prevent overheating, effectively improving the device's operational stability and service life. This design not only ensures the system's intelligent heat dissipation function, but also takes into account the need for low-cost fans, avoiding the economic burden of using high-cost fans.

[0034] Specifically, this effectively solves the problem of two-wire fans lacking PWM speed regulation, thus failing to dissipate heat for onboard electronic devices in a timely manner. Its operating principle is to use temperature detection module 2 to obtain temperature signals from onboard electronic devices in real time. When the device temperature exceeds a preset threshold, temperature detection module 2 transmits the temperature signal to control module 1. Based on the received temperature signal, control module 1 generates a reference voltage and an adjustment voltage signal, which are sent to voltage-stabilized power supply module 3 and speed regulation module 4, respectively. Speed ​​regulation module 4 adjusts the feedback signal by varying its resistance, thereby affecting the output voltage of voltage-stabilized power supply module 3. Voltage-stabilized power supply module 3 adjusts the supply voltage based on changes in the feedback signal, ultimately controlling the fan speed. This allows the fan to flexibly adjust its speed under varying temperature conditions, effectively dissipating heat for onboard electronic devices. In this way, the system not only utilizes lower-cost two-wire fans, avoiding the high costs of three-wire or four-wire fans, but also ensures rapid cooling of electronic devices in high-temperature environments, thereby improving their reliability and service life.

[0035] Further, such as Figure 2 As shown, the voltage-stabilized power supply module 3 includes an LDO chip, the VIN pin of the LDO chip is connected to the power supply, the VOUT pin of the LDO chip is connected to the fan, and the speed regulation module 4 is connected between the VOUT pin of the LDO chip and the FB pin of the LDO chip.

[0036] In this embodiment, a voltage-regulated power supply is achieved through an LDO chip. The LDO chip can provide a stable voltage output to the fan at the power input terminal, ensuring that the voltage is stable and does not fluctuate during fan operation, thereby improving the fan's operating stability. The VIN pin of the LDO chip is connected to the power supply, the VOUT pin is connected to the fan, and the FB pin is connected to the speed regulation module 4. By adjusting the feedback voltage signal, the output voltage of the LDO chip is controlled, thereby adjusting the fan's speed. Through this design, not only can the stable operation of the fan under different operating conditions be guaranteed, but also the voltage and speed can be dynamically adjusted according to changes in system temperature, achieving effective heat dissipation control.

[0037] Specifically, an LDO chip can be used to achieve a regulated power supply. The LDO chip can provide a stable voltage output to the fan at the power input terminal, ensuring a stable voltage without fluctuations during fan operation, thereby improving the fan's operating stability. In addition, the speed regulation module 4 is connected between the VOUT and FB pins of the LDO chip, which can provide precise feedback regulation of the output voltage, thereby effectively improving the fan's speed control accuracy.

[0038] Further, such as Figure 2 As shown, the speed regulation module 4 includes a plurality of voltage dividing units and a resistor Ru arranged in parallel, the first end of the resistor Ru is connected to the VOUT pin of the LDO chip, the second end of the resistor Ru is connected to the first end of the voltage dividing unit, the second end of the voltage dividing unit is grounded, and the third end of the voltage dividing unit is connected to the adjustment voltage signal output end of the control module 1.

[0039] In this embodiment, fan speed is regulated via multiple voltage divider units and a resistor Ru arranged in parallel. The first end of resistor Ru is connected to the VOUT pin of the LDO chip, the second end is connected to the first end of the voltage divider unit, and the third end of the voltage divider unit is connected to the regulated voltage signal output terminal of control module 1. This structure controls the voltage variation of the voltage divider unit via the regulated voltage signal output by control module 1, thereby regulating the feedback signal, thereby affecting the output voltage of the voltage-stabilized power supply module 3 and finely adjusting the fan speed. This design not only flexibly adapts to fan speed requirements under different temperature conditions but also improves heat dissipation.

[0040] Specifically, the fan speed can be adjusted by using multiple voltage divider units and resistors Ru arranged in parallel. Resistor Ru is connected to the VOUT pin of the LDO chip and the voltage divider unit, and the third end of the voltage divider unit is connected to the regulated voltage signal output terminal of the control module 1. This structure can effectively adjust the voltage, thereby finely controlling the fan speed and improving the fan's heat dissipation effect.

[0041] Preferably, the speed control strategy of this circuit is that when the module enters the fan rotation mode, the system turns on the fan for cooling; when the SOC enters the fan rotation mode, the system periodically reads the internal temperature of the SOC; the SOC controls the fan speed to cool down according to the fan control curve; the SOC can control the fan speed control curve according to experimental data; this circuit is designed with three adjustable gears, and the user can increase the gear adjustment according to actual needs;

[0042] like Figure 2 As shown in the figure, the speed control state of the designed gear adjustment circuit is as follows:

[0043] In the above circuit, the SOC passes the core temperature self-test and, when the fan must be turned on, sets GPIO1 high to enable the LDO power supply.

[0044] When the fan level is 1, the SOC can set GPIO1 and GPIO2 high at the same time. GPIO3 and GPIO4 are closed.

[0045] When the fan level is 2, the SOC can set GPIO1, GPIO2, and GPIO3 high at the same time, and GPIO4 is closed.

[0046] When the fan gear is 3, the SOC can set GPIO1, GPIO2, GPIO3, and GPIO4 high at the same time.

[0047] The above and so on, when multi-level speed adjustment is required, GPIO control circuits can be added accordingly.

[0048] When it is not needed, GPIO1 can be turned off.

[0049] Further, such as Figure 2 As shown, the voltage dividing unit includes at least a resistor Rd and a switch conduction element, the first end of the resistor Rd is connected to the second end of the resistor Ru, the second end of the resistor Rd is connected to the first conduction end of the switch conduction element, the second conduction end of the switch conduction element is grounded, the controlled end of the switch conduction element is connected to the regulated voltage signal output end of the control module 1, and the common node between the first end of the resistor Rd and the resistor Ru is connected to the FB pin of the LDO chip.

[0050] In this embodiment, accurate distribution and regulation of voltage are achieved through the cooperation of the resistor Rd and the switch conduction element in the voltage divider unit. The first end of the resistor Rd is connected to the second end of the resistor Ru, and the second end is connected to the first conduction end of the switch conduction element, and the second conduction end of the switch conduction element is grounded. The regulating voltage signal of the control module 1 adjusts the conduction state of the resistor Rd by controlling the on-off of the switch conduction element, controls the size of the feedback signal, and ultimately affects the output voltage of the LDO chip. This design can respond quickly when the temperature of the device changes, adjust the fan speed in time, and improve the temperature control capability and regulation accuracy of the system. As mentioned above, there will be three gear adjustments, and naturally there will be three resistors Rd. Figure 2 Indicated as Rd1, Rd2 and Rd3.

[0051] Specifically, the voltage can be precisely distributed and regulated through the coordination of resistor Rd and the switch element in the voltage divider. The regulated voltage signal from control module 1 controls the conduction state of resistor Rd via the switch element, adjusting the resistance value and thereby controlling the voltage fed back to the FB pin of the LDO chip. This design enables rapid response to temperature changes, adjusting fan speed, and improving the response speed and accuracy of the fan speed regulation system.

[0052] Further, such as Figure 2 As shown, the switch conduction element is a MOS tube.

[0053] In this embodiment, a MOS transistor is used as the switching element. Leveraging its low on-resistance and high switching speed, the MOS transistor can quickly switch the resistor Rd between on and off states, enabling faster and more accurate voltage distribution and rapid fan speed regulation. The use of the MOS transistor not only improves the circuit's response speed and regulation accuracy, but also reduces power consumption while improving the overall efficiency of the fan speed control system.

[0054] Further, such as Figure 2 As shown, the MOS tube is an NMOS tube.

[0055] In this embodiment, an NMOS transistor is used as the switching element. NMOS transistors have a low on-state voltage, enabling efficient current flow control while also reducing power consumption. The fast response and low loss characteristics of NMOS transistors make them ideal switching elements in fan speed regulation circuits. This design further improves the efficiency and accuracy of fan regulation, ensuring that the fan can quickly adjust its speed when the temperature changes, maintaining stable operation of the vehicle's electronic equipment.

[0056] Further, such as Figure 2As shown, the control module 1 includes a SOC chip, and a plurality of GPIO ports are provided on the SOC chip, wherein one of the GPIO ports serves as the reference voltage signal output end of the control module 1 and is connected to the EN pin of the LDO chip, and the other GPIO ports serve as the adjustment voltage signal output end of the control module 1 and are connected to the controlled end of the switch conduction element.

[0057] In this embodiment, the GPIO port of the SOC chip is used to control the EN pin of the LDO chip to control the fan's power supply. When the temperature detection module 2 detects that the device temperature exceeds a threshold, the SOC chip outputs a reference voltage signal through the GPIO port, activating the EN pin of the LDO chip and turning on the fan power supply. Furthermore, the SOC chip's other GPIO ports are used to output regulated voltage signals to control the switch-on elements in the speed adjustment module 4, achieving precise adjustment of the fan's speed. This design ensures that the fan can automatically adjust its speed based on changes in device temperature, improving heat dissipation while maintaining the intelligence and automation level of the entire system.

[0058] Specifically, the enable pin of the LDO chip can be controlled through the GPIO port of the SOC chip to achieve on-off control of the fan power supply. In addition, other GPIO ports can output regulated voltage signals to control the on-off state of the switch conduction element, thereby achieving precise adjustment of the fan speed, ensuring that the heat dissipation demand can respond to the temperature changes of the equipment in real time, and further improving the intelligence and automation level of the system.

[0059] Further, such as Figure 2 As shown, the SOC chip is provided with a core temperature self-detection unit.

[0060] In this embodiment, the SOC chip's core temperature self-monitoring unit monitors the SOC chip's internal temperature in real time. This unit ensures that when the SOC temperature is too high, the fan speed is promptly controlled to accelerate heat dissipation and prevent device overheating. This feature not only enhances the intelligence of fan speed regulation but also further improves overall system reliability, preventing device damage or performance degradation caused by excessive temperatures.

[0061] Specifically, the core temperature self-test unit integrated on the SOC chip can monitor the internal temperature of the chip in real time, ensuring a quick response when the chip temperature rises, adjusting the fan speed or other heat dissipation measures, thereby improving the overall reliability and heat dissipation efficiency of the system and preventing performance degradation or damage to the device due to overheating.

[0062] Further, such as Figure 2 As shown, a capacitor is connected between the VOUT pin of the LDO chip and the ground.

[0063] In this embodiment, a capacitor is connected between the VOUT pin of the LDO chip and ground to stabilize the voltage and reduce fluctuations in the output voltage. This filtering design ensures a stable voltage during fan operation, effectively extending the fan's service life. It also improves the stability and reliability of the entire system and prevents the impact of voltage fluctuations on the fan.

[0064] Specifically, by connecting a capacitor between the VOUT pin of the LDO chip and the ground, the capacitor can act as a filter, reduce voltage fluctuations in the power supply output, and ensure that the fan operates under stable power supply voltage, thereby improving the fan's service life and system stability.

[0065] Further, such as Figure 2 As shown, the temperature detection module 2 includes at least one thermistor.

[0066] In this embodiment, the temperature of onboard electronic devices is precisely monitored using a thermistor in temperature detection module 2. The thermistor's resistance changes with temperature, accurately transmitting the temperature signal to control module 1. Based on temperature fluctuations, control module 1 can adjust the fan speed in real time, ensuring that the electronic devices maintain effective heat dissipation under varying temperature conditions. This design effectively prevents device overheating and improves system stability and safety.

[0067] Specifically, the temperature of the on-board electronic equipment can be monitored in real time through the thermistor in the temperature detection module 2. The resistance of the thermistor changes with the temperature, and the temperature signal can be accurately transmitted to the control module 1, thereby achieving precise control of the fan speed, avoiding overheating of the equipment, and improving the heat dissipation performance and safety of the system.

[0068] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A vehicle-mounted cooling fan speed control circuit, characterized in that: The invention comprises a control module (1), a temperature detection module (2), a voltage-stabilized power supply module (3) and a speed regulating module (4), wherein the power input end of the voltage-stabilized power supply module (3) is connected to a power supply, the power output end of the voltage-stabilized power supply module (3) is connected to a fan, the temperature detection module (2) is used to obtain the device temperature of the vehicle-mounted electronic device, the temperature signal output end of the temperature detection module (2) is connected to the temperature signal input end of the control module (1), the reference voltage signal output end of the control module (1) is connected to the enable signal input end of the voltage-stabilized power supply module (3), the adjustment voltage signal output end of the control module (1) is connected to the enable signal input end of the speed regulating module (4), and the signal output end of the speed regulating module (4) is connected to the feedback signal input end of the voltage-stabilized power supply module (3). When the temperature detection module (2) detects that the device temperature exceeds a preset threshold, the control module (1) changes the resistance value of the speed regulating module (4) so ​​that the voltage-stabilized power supply module (3) outputs a corresponding supply voltage, thereby regulating the speed of the fan.

2. The vehicle-mounted cooling fan speed control circuit according to claim 1, characterized in that: The voltage-stabilized power supply module (3) comprises an LDO chip, a VIN pin of the LDO chip is connected to a power source, a VOUT pin of the LDO chip is connected to a fan, and a speed regulating module (4) is connected between the VOUT pin of the LDO chip and the FB pin of the LDO chip.

3. The vehicle-mounted cooling fan speed control circuit according to claim 2, characterized in that: The speed regulating module (4) comprises a plurality of voltage dividing units and a resistor Ru arranged in parallel, wherein the first end of the resistor Ru is connected to the VOUT pin of the LDO chip, the second end of the resistor Ru is connected to the first end of the voltage dividing unit, the second end of the voltage dividing unit is grounded, and the third end of the voltage dividing unit is connected to the regulating voltage signal output end of the control module (1).

4. The vehicle-mounted cooling fan speed control circuit according to claim 3, characterized in that: The voltage dividing unit comprises at least a resistor Rd and a switch conduction element, wherein the first end of the resistor Rd is connected to the second end of the resistor Ru, the second end of the resistor Rd is connected to the first conduction end of the switch conduction element, the second conduction end of the switch conduction element is grounded, the controlled end of the switch conduction element is connected to the regulated voltage signal output end of the control module (1), and the common node between the first end of the resistor Rd and the resistor Ru is connected to the FB pin of the LDO chip.

5. The vehicle-mounted cooling fan speed control circuit according to claim 4, characterized in that: The switch conduction element is a MOS tube.

6. The vehicle-mounted cooling fan speed control circuit according to claim 5, characterized in that: The MOS tube is an NMOS tube.

7. The vehicle-mounted cooling fan speed control circuit according to claim 4, characterized in that: The control module (1) includes a SOC chip, and a plurality of GPIO ports are provided on the SOC chip, wherein one of the GPIO ports serves as a reference voltage signal output terminal of the control module (1) and is connected to an EN pin of the LDO chip, and the other GPIO ports serve as adjustment voltage signal output terminals of the control module (1) and are connected to the controlled terminals of the switch conduction element.

8. The vehicle-mounted cooling fan speed control circuit according to claim 7, characterized in that: The SOC chip is provided with a core temperature self-detection unit.

9. The vehicle-mounted cooling fan speed control circuit according to claim 2, characterized in that: A capacitor is connected between the VOUT pin of the LDO chip and the ground.

10. The vehicle-mounted cooling fan speed control circuit according to claim 1, characterized in that: The temperature detection module (2) comprises at least one thermistor.

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