CN216008986U

CN216008986U - Fan control circuit and electronic equipment

Info

Publication number: CN216008986U
Application number: CN202121150314.1U
Authority: CN
Inventors: 苏昭梦; 严飞燕; 陈肇元
Original assignee: Faurecia Clarion Electronics Xiamen Co Ltd
Current assignee: Faurecia Clarion Electronics Xiamen Co Ltd
Priority date: 2021-05-26
Filing date: 2021-05-26
Publication date: 2022-03-11
Anticipated expiration: 2031-05-26

Abstract

The application provides a fan control circuit and electronic equipment, relates to the technical field of vehicles, and can solve the problems of small voltage regulation range and low voltage regulation precision of the fan control circuit in the related art; the fan control circuit includes: the voltage conversion module and the voltage regulation module; the voltage conversion module is used for acquiring pulse signals with different duty ratios under the condition that the current temperature is higher than the preset temperature and converting the pulse signals into direct-current voltage; the duty ratio of the pulse signal is determined by the current temperature; the direct current voltages corresponding to the pulse signals with different duty ratios are different; the voltage adjusting module is electrically connected with the voltage conversion module and the fan respectively; the voltage adjusting module consists of a common emitter circuit and a divider resistor; the voltage adjusting module is used for adjusting the direct current voltage output by the voltage converting module into the input voltage of the fan so as to enable the fan to work according to the input voltage, and the direct current voltage is in direct proportion to the input voltage.

Description

Fan control circuit and electronic equipment

Technical Field

The utility model relates to the technical field of vehicles, in particular to a fan control circuit and electronic equipment.

Background

An in-vehicle infotainment (IVI) is a vehicle-mounted comprehensive information processing system formed by adopting a vehicle-mounted special central processing unit and based on a vehicle body bus system and internet service. The central processing unit in the vehicle-mounted comprehensive information processing system can convert part of electric energy into heat to be dissipated when the central processing unit works, and the working efficiency of the system can be influenced when the system is overheated.

In the prior art, the cooling fan is arranged, and the rotating speed of the cooling fan is controlled by adjusting the output voltage of the fan control circuit, so that the purpose of cooling the central processing unit is achieved. However, the fan control circuit in the related art has a small voltage regulation range and low voltage regulation precision, so that the cooling effect of the cooling fan on the central processing unit is not obvious.

SUMMERY OF THE UTILITY MODEL

The embodiment of the application provides a fan control circuit and electronic equipment, and the problems that the fan control circuit in the related art is small in voltage regulation range and low in voltage regulation precision can be solved.

In a first aspect, a fan control circuit is provided, which includes: the voltage conversion module and the voltage regulation module; the voltage conversion module is used for acquiring pulse signals with different duty ratios under the condition that the current temperature is higher than the preset temperature and converting the pulse signals into direct-current voltage; the duty ratio of the pulse signal is determined by the current temperature; the direct current voltages corresponding to the pulse signals with different duty ratios are different; the voltage adjusting module is electrically connected with the voltage conversion module and the fan respectively; the voltage adjusting module consists of a common emitter circuit and a divider resistor; the voltage adjusting module is used for adjusting the direct current voltage output by the voltage converting module into the input voltage of the fan so as to enable the fan to work according to the input voltage, and the direct current voltage is in direct proportion to the input voltage.

Optionally, the voltage conversion module includes a first resistor, a second resistor, a first capacitor, and a second capacitor; the first end of the first resistor is electrically connected with the pulse signal end, and the second end of the first resistor is respectively electrically connected with the first end of the second resistor and the first end of the first capacitor; the second end of the first capacitor is grounded; the second end of the second resistor is electrically connected with the voltage adjusting module and the first end of the second capacitor respectively, and the second end of the second capacitor is grounded.

Optionally, the voltage adjustment module includes a first transistor, a second transistor, a third resistor, a fourth resistor, and a fifth resistor; a first pole of the first transistor is electrically connected with the voltage conversion module, and a second pole of the first transistor is respectively electrically connected with a first end of the third resistor and a second pole of the second transistor; a third pole of the first transistor is electrically connected with the first voltage end; a first pole of the second transistor is electrically connected with a first end of the fourth resistor and a first end of the fifth resistor respectively, a second pole of the second transistor is electrically connected with a first end of the third resistor, and a third pole of the second transistor is electrically connected with the fan; the second end of the third resistor and the second end of the fourth resistor are grounded, and the second end of the fifth resistor is electrically connected with the fan.

Optionally, the fan control circuit further includes: a switch module; the switch module is electrically connected with the first voltage end, the voltage adjusting module and the fan respectively; the switch module is used for controlling the fan to be switched on or off under the action of the voltage of the first voltage end and the direct-current voltage

Optionally, the switch module includes a third transistor, a sixth resistor, and a third capacitor; the first pole of the third transistor is electrically connected with the first end of the sixth resistor, the first end of the third capacitor and the voltage adjusting module respectively, the second pole of the third transistor is electrically connected with the second end of the sixth resistor, the second end of the third capacitor and the first voltage end respectively, and the third pole of the third transistor is electrically connected with the fan.

Optionally, the fan control circuit further includes: an overcurrent protection module; the overcurrent protection module is electrically connected with the first voltage end and the switch module respectively; and under the condition that the current of the fan is greater than the preset current, the overcurrent protection module is used for controlling the switch module to be switched off under the action of the signal of the first voltage end.

Optionally, the overcurrent protection module includes a seventh resistor, an eighth resistor, and a fourth transistor; a second electrode of the fourth transistor is respectively and electrically connected with a first end of the seventh resistor and the first voltage end, and a first electrode of the fourth transistor is respectively and electrically connected with a second end of the seventh resistor and the switch module; a third pole of the fourth transistor is electrically connected to a first end of the eighth resistor, and a second end of the eighth resistor is electrically connected to the switch module.

Optionally, the overcurrent protection module further includes a ninth resistor and a tenth resistor; a first end of the ninth resistor is electrically connected to the first pole of the fourth transistor, a second end of the ninth resistor is electrically connected to a first end of the tenth resistor, and a second end of the tenth resistor is electrically connected to a second end of the seventh resistor and the switch module, respectively.

In a second aspect, an electronic device is provided, which includes a control unit, a temperature acquisition unit, a fan, and the fan control circuit as described in the first aspect or any optional manner of the first aspect; the control unit is respectively electrically connected with the temperature acquisition unit and the fan control circuit, and the fan control circuit is electrically connected with the fan; the temperature acquisition unit is used for acquiring the current temperature and sending the current temperature to the control unit; the control unit is used for outputting pulse signals with different duty ratios to the fan control circuit according to the current temperature.

Drawings

Fig. 1 is a schematic structural diagram of an electronic device according to an embodiment of the present disclosure;

fig. 2 is a schematic structural diagram of a fan control circuit according to an embodiment of the present disclosure;

fig. 3 is a schematic structural diagram of another fan control circuit according to an embodiment of the present disclosure;

fig. 4 is a schematic structural diagram of another fan control circuit according to an embodiment of the present disclosure;

fig. 5 is a schematic structural diagram of another fan control circuit according to an embodiment of the present disclosure;

fig. 6 is a schematic structural diagram of another fan control circuit according to an embodiment of the present disclosure;

fig. 7 is a schematic structural diagram of another fan control circuit according to an embodiment of the present disclosure.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the following, the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or indicating the number of technical features indicated. Thus, features defining "first", "second", may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, "a plurality" means two or more unless otherwise specified.

In describing some embodiments, expressions of "coupled" and "connected," along with their derivatives, may be used. For example, the term "connected" may be used in describing some embodiments to indicate that two or more elements are in direct physical or point contact with each other. As another example, some embodiments may be described using the term "coupled" to indicate that two or more elements are in direct physical or electrical contact. However, the terms "coupled" or "communicatively coupled" may also mean that two or more elements are not in direct contact with each other, but yet still co-operate or interact with each other. The embodiments disclosed herein are not necessarily limited to the contents herein.

Fig. 1 provides an electronic device, which may be applied to an IVI system, for an embodiment of the present application. As shown in fig. 1, the electronic apparatus 1 includes a control unit 10, a temperature acquisition unit 11, a fan control circuit 12, and a fan.

The control unit 10 is electrically connected with the temperature acquisition unit 11 and the fan control circuit 12, and the fan control circuit 12 is electrically connected with the fan.

Specifically, the temperature acquisition unit 11 is configured to acquire a current temperature of the electronic device 1, and send the acquired current temperature to the control unit 10.

For example, the temperature acquisition unit 11 may be a temperature sensor, or other suitable components capable of acquiring temperature, which is not limited in the embodiments of the present application.

The control unit 10 is used for receiving the current temperature collected by the temperature collecting unit 11. After the control unit 10 receives the current temperature, if the current temperature is higher than the preset temperature, the control unit 10 inputs a pulse signal with a certain duty ratio to the fan control circuit 12; at the same time, the fan control circuit 12 supplies a power supply voltage to the fan so that the fan rotates under the control of the power supply voltage and the pulse signal.

It should be noted that the preset temperature is a preset temperature, and may be set according to an actual situation, which is not limited in the embodiment of the present application.

In addition, the control unit 10 may input pulse signals with different duty ratios to the fan control circuit 12 according to the change of the current temperature. For example, if the current temperature is low, the duty ratio of the pulse signal input to the fan control circuit 12 by the control unit 10 is small; if the current temperature is high, the duty ratio of the pulse signal input to the fan control circuit 12 by the control unit 10 is large.

Illustratively, the control unit 10 may be, for example, a Micro Controller Unit (MCU).

The input voltage of the fan used in the IVI system is in the range of 7V to 13.5V, and thus the rotation speed of the fan can be adjusted by adjusting the input voltage of the fan. Based on this, the fan control circuit 12 included in the electronic device 1 provided in the embodiment of the present application may be configured to adjust the input voltage of the fan and change the rotation speed of the fan according to the input voltage of the fan.

Specifically, the fan control circuit 12 is configured to receive the pulse signal sent by the control unit 10, and determine an input voltage of the fan according to the pulse signal, so that the fan operates according to the input voltage.

For example, the duty ratios of the pulse signals received by the fan control unit 10 are different, and the determined input voltages of the fans are also different, so that the input voltages of the fans can be changed by adjusting the duty ratios of the pulse signals, the rotating speed of the fans can be adjusted, the duty ratios of the pulse signals can be adjusted according to the current temperature collected by the temperature collection unit 11, the input voltages of the fans can be adjusted according to the pulse signals with different duty ratios, the rotating speed of the fans can be changed according to the input voltages, and a good heat dissipation effect can be achieved.

Optionally, the electronic device 1 further comprises a feedback unit 13. Wherein the feedback unit 13 is electrically connected with the control unit 10 and the fan. The feedback unit 13 is configured to obtain operation information of the fan and send the operation information to the control unit 10, so that the control unit 10 determines an operation state of the fan according to the operation information.

For example, the operation information may be information on the rotation speed of the fan or information on the failure of the fan.

Taking the operation information as the rotation speed information of the fan as an example, specifically, the feedback unit 13 acquires a pulse signal output by the output end of the fan and sends the pulse signal to the control unit 10. After receiving the pulse signal sent by the feedback unit 14, the control unit 10 determines the rotation speed of the fan according to the frequency of the pulse signal; and if the frequency of the pulse signal is unstable, judging that the fan is locked.

In the embodiment of the present application, the control unit 10, the fan control circuit 12, and the feedback unit 13 may be integrated together, or may be separate devices, which is not limited in the embodiment of the present application. Fig. 1 illustrates an example in which the control unit 10, the fan control circuit 12, and the feedback unit 13 are independent devices.

Fig. 2 is a schematic structural diagram of a fan control circuit 12 according to an embodiment of the present disclosure; as shown in fig. 2, the fan control circuit 12 includes a voltage conversion module 120 and a voltage adjustment module 121.

Specifically, the voltage conversion module 120 is configured to obtain pulse signals with different duty ratios under the condition that the current temperature is greater than the preset temperature, and convert the pulse signals into a direct current voltage. The duty ratio of the pulse signals is determined by the current temperature, and the direct-current voltages corresponding to the pulse signals with different duty ratios are different.

The voltage adjusting module 121 is electrically connected to the voltage converting module 120 and the fan respectively; the voltage adjustment module 121 is composed of a common emitter circuit and a voltage dividing resistor; the voltage adjusting module 121 is configured to adjust the dc voltage output by the voltage converting module to an input voltage of the fan, so that the fan operates according to the input voltage; wherein the dc voltage is proportional to the input voltage.

With reference to the foregoing embodiment, the control unit 10 outputs pulse signals with different duty ratios according to the current temperature, and sends the pulse signals with different duty ratios to the fan control circuit 12, so that the voltage conversion module 120 included in the fan control circuit 12 obtains the pulse signals with different duty ratios.

It should be noted that the pulse signal in the embodiment of the present application may be a PWM (pulse width modulation) signal.

Illustratively, the voltage conversion module 120 may be an RC circuit (resistor-capacitor circuit). When a pulse signal with a certain frequency is input into the RC circuit, the RC circuit attenuates the ac voltage of the pulse signal, thereby achieving a filtering effect, so that the voltage conversion module 120 outputs a dc voltage.

After filtering the ac voltage of the pulse signal, the output dc voltage is smaller than the ac voltage of the pulse signal. For example, after a pulse signal with a voltage of 3.3V, a frequency of 100Hz, and a constant duty ratio passes through the voltage conversion module 120, the output dc voltage is less than 3.3V.

Illustratively, the duty cycle of the pulse signal is proportional to the dc voltage. For example, the direct-current voltage increases as the duty ratio of the pulse signal increases; alternatively, the direct-current voltage decreases as the duty ratio of the pulse signal decreases.

With reference to the above embodiments, the voltage conversion module 120 converts the pulse signal into a dc voltage, and then inputs the dc voltage to the voltage adjustment module 121; the voltage adjusting module 121 adjusts the dc voltage output by the voltage converting module to an input voltage of the fan, so that the fan operates according to the input voltage.

Illustratively, since the voltage adjustment module 121 is composed of a common transmitting circuit and a voltage dividing resistor, the voltage adjustment module 121 may linearly adjust the dc voltage to the input voltage, that is, the dc voltage and the input voltage have a linear relationship.

It should be noted that, the linear relationship between the dc voltage and the input voltage means: the dc voltage is proportional to the input voltage. For example, the input voltage increases with increasing dc voltage; alternatively, the input voltage decreases as the dc voltage decreases.

In summary, when the fan control circuit 12 provided in the embodiment of the present application is used, the voltage conversion module 120 can convert the obtained pulse signals with different duty ratios into different dc voltages, input the converted dc voltages into the voltage adjustment module 121, and then the voltage adjustment module 121 adjusts the dc voltages output by the voltage conversion module into the input voltages of the fan, so that the fan operates according to the input voltages; because the duty ratio of the pulse signal is determined by the current temperature, the duty ratio of the pulse signal can be adjusted according to the current temperature, the input voltage of the fan is further adjusted, the rotating speed of the fan is adjusted according to the input voltage of the fan, and the improvement of the heat dissipation effect of the fan is facilitated.

In addition, according to the embodiment of the application, the pulse signal is converted into the direct-current voltage, and then the direct-current voltage is adjusted to be the input voltage of the fan, so that the problems that in the related art, the voltage adjusting range is small and the voltage adjusting precision is low after the pulse signal is directly adjusted to be the input voltage of the fan are solved.

Optionally, with reference to fig. 2, as shown in fig. 3, the voltage conversion module 120 includes a first resistor R1, a second resistor R2, a first capacitor C1, and a second capacitor C2.

Specifically, a first end of the first resistor R1 is electrically connected to the pulse signal terminal PWM, and a second end of the first resistor R1 is electrically connected to a first end of the second resistor R2 and a first end of the first capacitor C1, respectively; the second end of the first capacitor C1 is grounded; a second terminal of the second resistor R2 is electrically connected to the voltage adjusting module 121 and a first terminal of the second capacitor C2, respectively, and a second terminal of the second capacitor is grounded.

Referring to fig. 3, the first capacitor C1 and the second capacitor C2 are two filter capacitors, the first resistor R1 and the second resistor R2 are two filter resistors, and the circuit may be referred to as a Π -type filter circuit because the first capacitor C1, the second resistor R2 and the second capacitor C2 are like the letter Π. As can be seen from fig. 3, the pi filter circuit is electrically connected to the output terminal of the pulse signal terminal PWM, so as to receive the pulse signal output by the pulse signal terminal PWM and convert the pulse signal into a dc voltage.

Illustratively, the pulse signal is first filtered by a first capacitor C1, and the first capacitor C1 filters out most of the ac voltage in the pulse signal. The pulse signal filtered by the first capacitor C1 passes through a filter circuit formed by a second resistor R2 and a second capacitor C2, the second capacitor C2 further filters the pulse signal, and a small amount of alternating voltage reaches the ground line through the second capacitor C2.

In summary, since the voltage conversion module 120 includes the first resistor R1, the second resistor R2, the first capacitor C1, and the second capacitor C2, the pulse signal output by the pulse signal terminal PWM can be filtered twice, so as to better filter the ac voltage in the pulse signal to obtain the dc voltage.

Optionally, referring to fig. 3, as shown in fig. 4, the voltage adjustment module 121 includes a first transistor Q1, a second transistor Q2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5.

Specifically, a first pole of the first transistor Q1 is electrically connected to the voltage converting module 120, and a second pole of the first transistor Q1 is electrically connected to a first terminal of the third resistor R3 and a second pole of the second transistor Q2, respectively; a third pole of the first transistor Q1 is electrically connected to the first voltage terminal VDD; a first pole of the second transistor Q2 is electrically connected to a first end of the fourth resistor R4 and a first end of the fifth resistor R5, respectively, a second pole of the second transistor Q2 is electrically connected to a first end of the third resistor R3, and a third pole of the second transistor Q2 is electrically connected to the fan; the second end of the third resistor R3 and the second end of the fourth resistor R4 are grounded, and the second end of the fifth resistor R5 is electrically connected with the fan.

Illustratively, the first transistor Q1 and the second transistor Q2 may be triodes. On this basis, the first poles of the first transistor Q1 and the second transistor Q2 may also be referred to as bases, the second poles of the first transistor Q1 and the second transistor Q2 may also be referred to as emitters, and the third poles of the first transistor Q1 and the second transistor Q2 may also be referred to as collectors.

In the case that the voltage conversion module 120 includes the first resistor R1, the second resistor R2, the first capacitor C1, and the second capacitor C2, the first pole of the first transistor Q1 is electrically connected to the second end of the second resistor R2 and the first end of the second capacitor C2.

As can be seen from fig. 4, the first transistor Q1 and the second transistor Q2 constitute a common emitter circuit that is symmetrical to each other, and thus the voltage V1 of the first pole of the first transistor Q1 and the voltage V2 of the first pole of the second transistor Q2 are equal.

It should be noted that, since the first transistor Q1 and the second transistor Q2 have internal resistances, the voltage V1 of the first pole of the first transistor Q1 and the voltage V2 of the first pole of the second transistor Q2 are not completely equal, and a certain error may exist. In a specific implementation, the error between the voltage V1 and the voltage V2 has no effect on the input voltage, and thus the error is negligible. In the embodiment of the present application, the voltage V1 and the voltage V2 are illustrated as being completely equal.

With the above embodiment, since the voltage V1 and the voltage V2 are equal, the voltage V2 of the first pole of the second transistor Q2 is equal to the dc voltage output by the voltage conversion module 120, so that the linear relationship between the voltage V2 of the first pole of the second transistor Q2 and the input voltage can be determined by the voltage dividing resistors (the third resistor R3, the fourth resistor R4, and the fifth resistor R5).

Specifically, the input voltage is equal to the sum of the voltage V2 of the first pole of the second transistor Q2 and the voltage across the fifth resistor R5.

Illustratively, the input voltage is labeled VFAN _ PWR and the voltage across the fifth resistor R5 is labeled V_R5(ii) a VFAN _ PWR ═ V₂+V_R5。

Wherein the content of the first and second substances,

then

Wherein, V₂Is the voltage of the first pole, R, of the second transistor Q2₅Is the resistance value, V, of the fifth resistor R5_xIs the voltage difference between the base and emitter of the second transistor Q2, R₃Is the resistance value of the third resistor R3₄Is the resistance of the fourth resistor R4.

In connection with the above embodiment, since the voltage V1 and the voltage V2 are equal, the input voltage of the fan can also be expressed as:

it can be understood that, for the same triode, the amplification factor β is fixed, so that, as can be seen from the above formula, the input voltage of the fan is linear (i.e. proportional) to the dc voltage (i.e. V1); therefore, the direct current voltage can be adjusted according to the duty ratio of the pulse signal, and the input voltage of the fan can be adjusted, that is, the input voltage of the fan can be adjusted by changing the duty ratio of the pulse signal, and the rotating speed of the fan can be adjusted through the input voltage.

It can be understood that the pulse signals with different duty ratios correspond to different direct current voltages, and thus different input voltages. Since the duty ratio of the pulse signal is proportional to the dc voltage, which is proportional to the input voltage, the duty ratio of the pulse signal is proportional to the input voltage. Table 1 shows dc voltages and input voltages corresponding to pulse signals with different duty ratios according to an exemplary embodiment.

PWM(％)	V1(V)	VFAN_PWR(V)
			40	1.19	4.55
50	1.49	5.89
			60	1.81	7.23
70	2.12	8.60
			80	2.44	9.97
90	2.76	11.3
			99	3.05	12.6

TABLE 1

As can be seen from table 1 above, the dc voltage and the input voltage increase as the duty ratio of the pulse signal increases.

In summary, the voltage adjustment module 121 includes a first transistor Q1, a second transistor Q2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5; the first transistor Q1 and the second transistor Q2 form a mutually symmetrical common emitter circuit, and the third resistor R3, the fourth resistor R4 and the fifth resistor R5 are voltage dividing resistors, so that a linear relation between an input voltage and a direct current voltage of the fan can be determined according to the common emitter circuit and the voltage dividing resistors, and the embodiment of the application can ensure that the input voltage of the fan can be adjusted by changing the duty ratio of the pulse signal.

Optionally, in conjunction with fig. 4, as shown in fig. 5, the fan control circuit 12 further includes a switch module 122; the switch module 122 is electrically connected to the first voltage terminal VDD, the voltage adjustment module 121 and the fan, respectively; the switch module 122 is used for controlling the fan to be turned on or off under the action of the voltage of the first voltage terminal VDD and the direct-current voltage.

Specifically, the switch module 122 is electrically connected to the input terminal of the voltage adjustment module 121. The voltage at the input end of the voltage adjustment module 121 is a dc voltage.

Illustratively, referring to fig. 5, the switch module 122 includes a third transistor Q3, a sixth resistor R6, and a third capacitor C3. A first pole of the third transistor Q3 is electrically connected to the first end of the sixth resistor R6, the first end of the third capacitor C3, and the voltage adjustment module 121, a second pole of the third transistor Q3 is electrically connected to the second end of the sixth resistor R6, the second end of the third capacitor C3, and the first voltage terminal VDD, and a third pole of the third transistor Q3 is electrically connected to the fan.

Illustratively, the third transistor Q3 may be a MOS transistor (field effect transistor). On this basis, the first pole of the third transistor Q3 may be a Gate (Gate), the second pole of the third transistor Q3 may be a Source (Source), and the third pole of the third transistor Q3 may be a Drain (Drain).

Note that the MOS transistor includes an NMOS transistor and a PMOS transistor, and in the embodiment of the present application, the third transistor Q3 is exemplified as a PMOS transistor.

Specifically, the voltage of the first voltage terminal VDD is input to the second pole (i.e., the source) of the third transistor Q3, and the dc voltage of the input terminal of the voltage adjustment module 121 is input to the third pole (i.e., the gate) of the third transistor Q3; when the gate voltage of the third transistor Q3 is less than the source voltage, the third transistor Q3 is turned on; since the third pole of the third transistor Q3 is electrically connected to the fan, the fan is controlled to start after the third transistor Q3 is turned on.

In addition, the sixth resistor R6 and the third capacitor C3 are connected in parallel between the gate and the source of the third transistor Q3, and the sixth resistor R6 plays a role of releasing charges to protect the third transistor Q3 from being easily damaged; the third capacitor C3 is used to improve the rapidity and stability of the switching of the third transistor Q3.

Illustratively, the voltage of the first voltage terminal VDD is 12V. When the voltage of the pulse signal is 3.3V and the frequency is 100Hz, the dc voltage is about 1.7V after the pulse signal is converted into the dc voltage.

Specifically, the resistance between the gate and the source of the MOS transistor is relatively large, so that a very high voltage can be generated across the equivalent capacitor of the gate and the source as long as a small amount of static charge exists, and if the small amount of static charge is not released in time, the voltages across the gate and the source are likely to cause the MOS transistor to be turned on by mistake, and even the gate and the source of the MOS transistor may be broken down, so that the static charge can be released by connecting a resistor in parallel between the gate and the source of the MOS transistor, thereby playing a role in protecting the MOS transistor.

Optionally, with reference to fig. 5, as shown in fig. 6, the fan control circuit 12 further includes: the overcurrent protection module 123, the overcurrent protection module 123 is electrically connected with the first voltage end VDD and the switch module 122 respectively; under the condition that the current of the fan is greater than the preset current, the over-current protection module is used for controlling the switch module 122 to be turned off under the action of the signal of the first voltage end VDD.

For example, referring to fig. 6, the overcurrent protection module 123 includes a seventh resistor R7, an eighth resistor R8, and a fourth transistor Q4. A second pole of the fourth transistor Q4 is electrically connected to the first terminal of the seventh resistor R7 and the first voltage terminal VDD, respectively, and a first pole of the fourth transistor Q4 is electrically connected to the second terminal of the seventh resistor R7 and the switch module 122, respectively; a third terminal of the fourth transistor Q4 is electrically connected to a first terminal of an eighth resistor R8, and a second terminal of the eighth resistor R8 is electrically connected to the switch module 122.

In the case that the switch module 122 includes the third transistor Q3, the sixth resistor R6 and the third capacitor C3, as shown in fig. 6, the first pole of the fourth transistor Q4 is electrically connected to the second end of the sixth resistor R6, and the second end of the eighth resistor R8 is electrically connected to the first end of the sixth resistor R6.

Specifically, when the current of the fan is larger than the predetermined current, i.e., the current flowing through the seventh resistor R7 is larger, the voltage difference across the seventh resistor R7 is larger. On the basis, if the voltage difference between the two ends of the seventh resistor R7 is greater than the voltage difference between the base and the emitter of the fourth transistor Q4, the fourth transistor Q4 is turned on, so the gate voltage of the third transistor Q3 is equal to the voltage of the first voltage terminal VDD, i.e., V3_G＝V_SThe third transistor Q3 is turned off so that the third transistor Q3 controls the fan to turn off.

In summary, when the current of the fan is greater than the preset current, the current flowing through the seventh resistor R7 is greater, which results in a greater voltage difference across the seventh resistor R7, and when the voltage difference across the seventh resistor R7 is greater than the voltage difference between the base and the emitter of the fourth transistor Q4, the fourth transistor Q4 is turned on, so that the gate voltage of the third transistor Q3 is equal to the voltage of the first voltage terminal VDD, and the third transistor Q3 is turned off, so that the third transistor Q3 controls the fan to be turned off, thereby solving the problem of fan damage caused by the excessive current.

Optionally, as shown in fig. 7, the overcurrent protection module 123 further includes a ninth resistor R9 and a tenth resistor R10; a first end of the ninth resistor R9 is electrically connected to the first pole of the fourth transistor Q4, a second end of the ninth resistor R9 is electrically connected to a first end of the tenth resistor R10, and second ends of the tenth resistor R10 are electrically connected to a second end of the seventh resistor R7 and the switch module 122, respectively.

In a case where the switch module 122 includes the third transistor Q3, the sixth resistor R6, and the third capacitor C3, the second terminal of the tenth resistor R10 is electrically connected to the second terminal of the sixth resistor R6.

Specifically, the ninth resistor R9 and the tenth resistor R10 are connected in series to the base of the fourth transistor Q4, and the ninth resistor R9 and the tenth resistor R10 can perform a voltage division function, so as to prevent the fourth transistor Q4 from being damaged when the voltage difference between the base and the emitter of the fourth transistor Q4 is large.

For example, in the case where the fan control circuit 12 and the feedback unit 13 are integrated together, as shown in fig. 7, the fan control circuit 12 further includes an eleventh resistor R11 and a twelfth resistor R12; a first end of the eleventh resistor R11 is electrically connected to the fan, and a second end of the eleventh resistor R11 is electrically connected to the control unit 10; a first end of the twelfth resistor R12 is electrically connected to the fan and a first end of the eleventh resistor R11, respectively, and a second end of the twelfth resistor R12 is electrically connected to the second voltage terminal VSS.

For example, the voltage of the second voltage terminal VSS is 3.3V, and the twelfth resistor R12 is used for pulling up the memory voltage of the fan to the second voltage terminal VSS.

Optionally, as shown in fig. 7, the fan control circuit 12 further includes a thirteenth resistor R13 and a fourteenth resistor R14, a first end of the thirteenth resistor R13 is electrically connected to the third pole of the second transistor Q2, and a second end of the thirteenth resistor R13 is electrically connected to the third pole of the third transistor Q3 and a second end of the fifth resistor R5; a first end of the fourteenth resistor R14 is electrically connected to the third pole of the first transistor Q1, and a second end of the fourteenth resistor R14 is electrically connected to the first pole of the third transistor Q3.

Specifically, the thirteenth resistor R13 and the fourteenth resistor R14 are pull-up resistors, and the thirteenth resistor R13 is used for pulling up the voltage of the third pole of the second transistor Q2; the fourteenth resistor R14 is used to pull up the voltage of the third pole of the first transistor Q1.

Optionally, as shown in fig. 7, the fan control circuit 12 further includes a diode D1, an anode of the diode D1 is electrically connected to the first voltage terminal VDD, and a cathode of the diode D1 is electrically connected to the first terminal of the seventh resistor R7 and the second terminal of the fourth transistor Q4.

Illustratively, when the first voltage terminal VDD is inputted with a voltage, the diode D1 is turned on such that the voltage of the first voltage terminal VDD is inputted to the second pole (i.e., the source) of the third transistor Q3.

The diode D1 may be a schottky diode, for example.

Optionally, as shown in fig. 7, the fan control circuit 12 further includes a fourth capacitor C4 and a fifth capacitor C5; a first end of the fourth capacitor C4 is electrically connected to the first voltage terminal VDD, and a second end of the fourth capacitor C4 is grounded; a first terminal of the fifth capacitor C5 is electrically connected to the input voltage terminal VFAN _ PWR of the fan, and a second terminal of the fifth capacitor C5 is grounded.

In particular, the fourth capacitor C4 and the fifth capacitor C5 function as charge storage and filtering.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A fan control circuit, comprising:

the voltage conversion module is used for acquiring pulse signals with different duty ratios under the condition that the current temperature is higher than the preset temperature and converting the pulse signals into direct-current voltage; the duty ratio of the pulse signal is determined by the current temperature; the direct current voltages corresponding to the pulse signals with different duty ratios are different;

the voltage adjusting module is electrically connected with the voltage conversion module and the fan respectively; the voltage adjusting module is composed of a common emitter circuit and a divider resistor; the voltage adjusting module is used for adjusting the direct current voltage output by the voltage converting module into the input voltage of the fan so as to enable the fan to work according to the input voltage, and the direct current voltage is in direct proportion to the input voltage.

2. The fan control circuit of claim 1, wherein the voltage conversion module comprises a first resistor, a second resistor, a first capacitor, and a second capacitor;

the first end of the first resistor is electrically connected with the pulse signal end, and the second end of the first resistor is respectively electrically connected with the first end of the second resistor and the first end of the first capacitor; the second end of the first capacitor is grounded;

the second end of the second resistor is electrically connected with the voltage adjusting module and the first end of the second capacitor respectively, and the second end of the second capacitor is grounded.

3. The fan control circuit of claim 1, wherein the voltage adjustment module comprises a first transistor, a second transistor, a third resistor, a fourth resistor, and a fifth resistor;

a first pole of the first transistor is electrically connected with the voltage conversion module, and a second pole of the first transistor is electrically connected with a first end of the third resistor and a second pole of the second transistor respectively; a third pole of the first transistor is electrically connected with a first voltage end;

a first pole of the second transistor is electrically connected with a first end of the fourth resistor and a first end of the fifth resistor respectively, a second pole of the second transistor is electrically connected with a first end of the third resistor, and a third pole of the second transistor is electrically connected with the fan;

the second ends of the third resistor and the fourth resistor are grounded, and the second end of the fifth resistor is electrically connected with the fan.

4. The fan control circuit of claim 1, further comprising: a switch module; the switch module is electrically connected with the first voltage end, the voltage adjusting module and the fan respectively; the switch module is used for controlling the fan to be switched on or switched off under the action of the voltage of the first voltage end and the direct-current voltage.

5. The fan control circuit of claim 4, wherein the switch module comprises a third transistor, a sixth resistor, and a third capacitor;

a first pole of the third transistor is electrically connected to the first end of the sixth resistor, the first end of the third capacitor, and the voltage adjustment module, a second pole of the third transistor is electrically connected to the second end of the sixth resistor, the second end of the third capacitor, and the first voltage terminal, and a third pole of the third transistor is electrically connected to the fan.

6. The fan control circuit of claim 4, further comprising: an overcurrent protection module; the overcurrent protection module is electrically connected with the first voltage end and the switch module respectively;

and under the condition that the current of the fan is greater than the preset current, the overcurrent protection module is used for controlling the switch module to be switched off under the action of the signal of the first voltage end.

7. The fan control circuit according to claim 6, wherein the over-current protection module comprises a seventh resistor, an eighth resistor and a fourth transistor;

a second electrode of the fourth transistor is electrically connected with the first end of the seventh resistor and the first voltage end respectively, and a first electrode of the fourth transistor is electrically connected with the second end of the seventh resistor and the switch module respectively; a third pole of the fourth transistor is electrically connected to a first end of the eighth resistor, and a second end of the eighth resistor is electrically connected to the switch module.

8. The fan control circuit of claim 6 wherein the over-current protection module further comprises a ninth resistor and a tenth resistor;

a first end of the ninth resistor is electrically connected to the first pole of the fourth transistor, a second end of the ninth resistor is electrically connected to a first end of the tenth resistor, and a second end of the tenth resistor is electrically connected to the second end of the seventh resistor and the switch module, respectively.

9. An electronic device comprising a control unit, a temperature acquisition unit, a fan, and a fan control circuit according to any one of claims 1-8;

the control unit is respectively electrically connected with the temperature acquisition unit and the fan control circuit, and the fan control circuit is electrically connected with the fan;

the temperature acquisition unit is used for acquiring the current temperature and sending the current temperature to the control unit; the control unit is used for outputting pulse signals with different duty ratios to the fan control circuit according to the current temperature.