Fan control circuit, fan and electronic equipment

Abstract

The present invention relates to a fan control circuit, a fan and an electronic device, wherein the fan control circuit comprises a first switch circuit and a second switch circuit, wherein when the electronic device is in a standby or shutdown state, the state signal of the electronic device is a low-level signal, which acts on the control end of the first switch circuit to make it in a cut-off state, thereby controlling the second switch circuit to be in a cut-off state, disconnecting the connection between the first DC power supply and the power supply circuit of the fan, and the fan cannot rotate due to power failure. Therefore, when the electronic device is in a standby or shutdown state, the fan control circuit can cut off the power supply of the fan, stop it from rotating, prevent its control from failing, and thereby control the fan more accurately.

Description

Technical Field

[0001] The present invention relates to the field of fan control, and in particular to a fan control circuit, a fan and an electronic device. Background Art

[0002] Electronic devices tend to generate a certain amount of heat during operation, and fans are needed to dissipate the heat. The fan drive signal is a PWM signal. Under normal circumstances, electronic devices control the rotation of the fan through the output of a PWM signal by an internal embedded controller (EC). However, when the electronic device is turned off, dormant, or sleeping, and the fan power supply is always on, the fan will continue to rotate and be uncontrolled, that is, the fan control fails. Summary of the invention

[0003] The embodiments of the present invention aim to provide a fan control circuit, a fan and an electronic device, which can more accurately control the fan and prevent control failure when the electronic device is in standby or shut down.

[0004] To solve the above technical problems, the embodiments of the present invention provide the following technical solutions:

[0005] In a first aspect, an embodiment of the present invention provides a fan control circuit, which is applied to a fan.

[0006] The fan is used to dissipate heat for the electronic equipment, and the fan control circuit includes: a first switch circuit and a second switch circuit;

[0007] The control end of the first switch circuit is used to access the state signal of the electronic device, the first end of the first switch circuit is connected to the control end of the second switch circuit, the second end of the first switch circuit is grounded, the third end of the first switch circuit is respectively connected to the first end of the second switch circuit and the first DC power supply, and the first switch circuit is used to control the working state of the second switch circuit;

[0008] The second end of the second switch circuit is connected to the power supply circuit of the fan, and the second switch circuit is used to control the connection state between the first DC power supply and the power supply circuit of the fan.

[0009] In some embodiments, the first switch circuit includes a first switch module and a voltage divider module;

[0010] The control end of the first switch module is used to access the state signal, the first end of the first switch module is connected to the first end of the voltage divider module, and the second end of the first switch module is grounded;

[0011] The second end of the voltage divider module is connected to the control end of the second switch circuit, and the third end of the voltage divider module is connected to the first DC power supply and the first end of the second switch circuit respectively.

[0012] In some embodiments, the first switch module includes a first MOS tube and a first resistor, the voltage divider module includes a second resistor and a third resistor, the drain of the first MOS tube is connected to the first end of the second resistor, the source of the first MOS tube is grounded, the gate of the first MOS tube is connected to one end of the first resistor, and the other end of the first resistor is used to access the state signal;

[0013] The second end of the second resistor is connected to the control end of the second switch circuit and the first end of the third resistor respectively, and the second end of the third resistor is connected to the first DC power supply and the first end of the second switch circuit respectively.

[0014] In some embodiments, the second switch circuit includes a second MOS transistor, a first capacitor and a second capacitor;

[0015] The source of the second MOS tube is respectively connected to the second end of the third resistor, the first DC power supply and one end of the first capacitor, the drain of the second MOS tube is connected to the power supply circuit of the fan, the gate of the second MOS tube is respectively connected to the other end of the first capacitor, one end of the second capacitor, the second end of the second resistor and the first end of the third resistor, and the other end of the second capacitor is grounded.

[0016] In some embodiments, the fan control circuit further includes a third switch circuit and a fourth switch circuit;

[0017] The control end of the third switch circuit is used to access the state signal, the first end of the third switch circuit is connected to the control end of the fourth switch circuit, the second end of the third switch circuit is grounded, the third end of the third switch circuit is connected to the second DC power supply, and the third switch circuit is used to control the working state of the fourth switch circuit;

[0018] The first end of the fourth switch circuit is connected to the PWM signal end, the PWM signal end is used to receive the PWM signal, the PWM signal is the driving signal of the fan, the second end of the fourth switch circuit is grounded, and the fourth switch circuit is used to control the PWM signal to drive the fan.

[0019] In some embodiments, the third switch circuit includes a third MOS transistor, a fourth resistor and a fifth resistor, and the fourth switch circuit includes a fourth MOS transistor;

[0020] One end of the fourth resistor is used to access the state signal, the other end of the fourth resistor is connected to the gate of the third MOS transistor, the source of the third MOS transistor is grounded, and the drain of the third MOS transistor is respectively connected to one end of the fifth resistor and the gate of the fourth MOS transistor;

[0021] The other end of the fifth resistor is connected to the second DC power supply, the source of the fourth MOS tube is grounded, and the drain of the fourth MOS tube is connected to the PWM signal end.

[0022] In some embodiments, a power selection circuit is also included, one end of the power selection circuit is connected to the power supply of the fan, and the other end of the power selection circuit is connected to the power supply circuit of the fan, and the power selection circuit is used to select a corresponding adaptation circuit according to the power supply of the fan.

[0023] In some embodiments, the power selection circuit includes a sixth resistor, a seventh resistor, a first switch, and a controller;

[0024] One end of the sixth resistor and one end of the seventh resistor are commonly connected to a power supply circuit of the fan;

[0025] The other end of the sixth resistor is connected to the first contact of the first switch, the other end of the seventh resistor is connected to the second contact of the first switch, the control end of the first switch is connected to the controller, the common end of the first switch is connected to the power supply of the fan, and the controller is used to control the working state of the first switch according to the power supply of the fan.

[0026] In a second aspect, an embodiment of the present invention provides a fan, the fan comprising the fan control circuit as described above, the fan being used to dissipate heat for an electronic device.

[0027] In a third aspect, an embodiment of the present invention provides an electronic device, wherein the electronic device includes the fan as described above.

[0028] In various embodiments of the present invention, the fan control circuit includes a first switch circuit and a second switch circuit, wherein when the electronic device is in standby or shutdown state, the state signal of the electronic device is a low-level signal, which acts on the control end of the first switch circuit to make it in a cut-off state, thereby controlling the second switch circuit to be in a cut-off state, disconnecting the connection between the first DC power supply and the power supply circuit of the fan, and the fan cannot rotate due to power failure. Therefore, when the electronic device is in standby or shutdown state, the fan control circuit can cut off the power supply of the fan, stop it from rotating, prevent its control from failing, and thus control the fan more accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0030] Figure 1 is a structural schematic diagram of a fan control circuit provided by an embodiment of the present invention;

[0031] Figure 2 is a structural schematic diagram of a fan control circuit provided by an embodiment of the present invention;

[0032] Figure 3 is a structural schematic diagram of a fan control circuit provided by an embodiment of the present invention;

[0033] Figure 4 is a circuit structure diagram of a fan control circuit provided by an embodiment of the present invention;

[0034] Figure 5 is a circuit structure diagram of a fan control circuit provided by an embodiment of the present invention;

[0035] Figure 6 It is a circuit structure diagram of one of the power selection circuits provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] See also Figure 1 , Figure 1 FIG. 1 is a schematic diagram of a circuit structure of a fan control circuit provided by an embodiment of the present invention. Figure 1 As shown, the fan control circuit is applied to a fan, wherein the fan is used to dissipate heat for electronic equipment. When the electronic equipment is working, each electronic component inside the electronic equipment will generate a certain amount of heat power, which increases the working temperature of the electronic components. The electronic components usually have a maximum working temperature specification requirement. Therefore, it is necessary to set a structural component for heat dissipation in the electronic equipment to achieve heat dissipation of each electronic component inside the electronic equipment, so that the electronic equipment can work stably for a long time.

[0038] Usually, a fan is arranged at the air outlet of the electronic device, so that the electronic device inhales air from the air inlet and blows it out from the air outlet through the fan to form an air flow channel, thereby ventilating and cooling the electronic components inside the electronic device.

[0039] It should be noted that electronic equipment includes but is not limited to computers, servers, boards, televisions, projection equipment, workstations and other equipment.

[0040] The fan drive signal is a PWM signal. Under normal circumstances, electronic devices control the rotation of the fan through the output of a PWM signal through an internal embedded controller (EC). When the electronic device is turned off, in sleep mode, or in dormancy mode, and the fan is powered on, the fan's internal circuit will pull up its PWM terminal to a high level, so that the PWM port always outputs a high-level signal, and the fan will keep rotating without being controlled.

[0041] Therefore, an embodiment of the present invention provides a fan control circuit to control the fan more accurately.

[0042] like Figure 1 As shown, the fan control circuit 100 includes a first switch circuit 10 and a second switch circuit 20, wherein the control end of the first switch circuit 10 is used to access the status signal of the electronic device, the first end of the first switch circuit 10 is respectively connected to the control end of the second switch circuit 20, the second end of the first switch circuit 10 is grounded, the third end of the first switch circuit 10 is respectively connected to the first end of the second switch circuit 20 and the first DC power supply 200, and the first switch circuit 10 is used to control the working state of the second switch circuit 20.

[0043] The second end of the second switch circuit 20 is connected to the power supply circuit 300 of the fan, and the second end of the second switch circuit 20 is used to output the power supply of the fan. The second switch circuit 20 is used to control the connection state between the first DC power supply 200 and the power supply circuit 300 of the fan.

[0044] The status signal of the electronic device is used to reflect the status of the electronic device. Different electronic devices have different status signals. If the electronic device is in normal operation, its status signal is a high level signal. If the electronic device is in shutdown, sleep or insomnia standby state, its status signal is a low level signal.

[0045] When the state signal is a high level signal, the first switch circuit 10 is in the on state, and when the state signal is a low level signal, the first switch circuit 10 is in the off state. The working state of the first switch circuit 10 can control the working state of the second switch circuit 20, control its on or off, and further control the connection state between the power supply of the fan and the power supply circuit 300 of the fan to control the rotation of the fan.

[0046] The first DC power supply 200 can be set as required, and can be a power supply size of a fan, such as 5 V or 12 V. The first DC power supply 200 can also be used as a power supply of a fan.

[0047] Combination Figure 1 , the working principle of the fan control circuit 100 can be described as follows:

[0048] If the electronic device is in the shutdown, sleep or hibernation state, the state signal of the electronic device is a low-level signal, and the low-level signal acts on the control end of the first switch circuit 10 to make it in the cut-off state, and then the control end of the second switch circuit 20 is low level, the second switch circuit 20 is cut off, the first DC power supply 200 is disconnected from the power supply circuit 300 of the fan, the fan has no power supply, and stops rotating due to power failure;

[0049] If the electronic device is in normal operation, the status signal of the electronic device is a high-level signal, which acts on the control end of the first switch circuit 10 to make it in a conducting state. The first DC power supply 200, the first end of the first switch circuit 10, the second end of the first switch circuit 10 and the ground form a closed loop. The first DC power supply 200 acts on the first end of the first switch circuit 10 and the control end of the second switch circuit 20, so that the control end of the second switch circuit 20 is high level, the second switch circuit 20 is turned on, and the first DC power supply 200 establishes a connection with the power supply circuit 300 of the fan through the second end of the second switch circuit 20 to supply power to the fan normally. The fan is controlled by the PWM signal sent by the EC of the electronic device and rotates normally.

[0050] In summary, when the electronic device is in standby or shutdown mode, the fan control circuit 100 can cut off the power supply of the fan to stop it from rotating, thereby preventing the control from failing, and thus being able to control the fan more accurately.

[0051] See also Figure 2 , Figure 2 is a schematic diagram of a fan control circuit provided by an embodiment of the present invention. Figure 2 As shown, the first switch circuit 10 includes a first switch module 11 and a voltage divider module 12. The control end of the first switch module 11 is used to access the state signal, the first end of the first switch module 11 is connected to the first end of the voltage divider module 12, the second end of the first switch module 11 is grounded, the second end of the voltage divider module 12 is connected to the control end of the second switch circuit 20, and the third end of the voltage divider module 12 is connected to the first end of the first DC power supply 200 and the first end of the second switch circuit 20, respectively.

[0052] When the status signal is a low level signal, the control end of the first switch module 11 is at a low level, the first switch module 11 is in the cut-off state, and then the second switch circuit 20 is also in the cut-off state, the first DC power supply 200 is disconnected from the power supply circuit 300 of the fan, and the fan stops rotating due to power failure, preventing it from rotating continuously and causing control failure.

[0053] When the status signal is a high level signal, the control end of the first switch module 11 is at a high level, the first switch module 11 is in a conducting state, the first DC power supply 200, the voltage divider module 12, the first end of the first switch module 11, the second end of the first switch module 11 and the ground form a loop, the voltage divider module 12 divides the first DC power supply 200, and the voltage divider signal acts on the control end of the second switch circuit 20, so that the second switch circuit 20 is turned on, the first DC power supply 200 establishes a connection with the power supply circuit 300 of the fan, and the first DC power supply 200 supplies power to the fan to enable it to work normally.

[0054] The voltage divider module 12 divides the voltage of the first DC power supply 200, and the voltage divider signal acts on the control end of the second switch circuit 20, which can prevent the voltage of the first DC power supply 200 from being too high and causing damage to the second switch circuit 20, thereby protecting it.

[0055] In some embodiments, please refer to Figure 2 The fan control circuit 100 further includes a power selection circuit 30. One end of the power selection circuit 30 is connected to the power supply 400 of the fan, and the other end of the power selection circuit 30 is connected to the power supply circuit 300 of the fan. The power selection circuit 30 is used to select a corresponding adapter circuit according to the power supply 400 of the fan.

[0056] Different models of fans may have different power supplies 400. Different power supplies 400 may have different adapter circuits between the power supplies 400 and the power supply circuit 300. By selecting different adapter circuits, the power supply 400 of the fan can be matched with the power supply circuit 300, so that different power supplies 400 can all power the fan.

[0057] Therefore, the fan control circuit 100 can make the fan compatible with different power supplies 400 by selecting a matching adapter circuit.

[0058] See also Figure 3 , Figure 3 is a schematic diagram of a fan control circuit provided by an embodiment of the present invention. Figure 3 As shown, the fan control circuit 100 further includes a third switch circuit 40 and a fourth switch circuit 50 .

[0059] The control end of the third switch circuit 40 is used to access the state signal, the first end of the third switch circuit 40 is connected to the control end of the fourth switch circuit 50, the second end of the third switch circuit 40 is grounded, the third end of the third switch circuit 40 is connected to the second DC power supply 500, and the third switch circuit 40 is used to control the working state of the fourth switch circuit 50. The first end of the fourth switch circuit 50 is connected to the PWM signal end, the PWM signal end is used to access the PWM signal, the PWM signal is the driving signal of the fan, the second end of the fourth switch circuit 50 is grounded, and the fourth switch circuit 50 is used to control the driving of the fan by the PWM signal.

[0060] When the electronic device is working normally, the electronic device outputs a PWM signal through the PWM signal terminal of the fan to drive the operation of the fan. When the electronic device is turned off or in standby mode, the PWM signal terminal of the fan will be pulled up to a high level by the circuit inside the fan, and the fan will keep rotating, and the control will fail.

[0061] Therefore, an embodiment of the present invention provides another solution to prevent fan control failure, that is, when the electronic device is turned off or in standby mode, the PWM signal end of the fan is pulled down to a low level to stop the fan from rotating, thereby preventing the fan from failing in control.

[0062] Specifically, combined Figure 3 , the working principle of the fan control circuit 100 can be described as follows:

[0063] When the electronic device is in shutdown or standby state, the state signal is a low-level signal, which acts on the control end of the third switch circuit 40 to make it in a cut-off state, and then the second DC power supply 500 acts on the control end of the fourth switch circuit 50 via the third end of the third switch circuit 40, and the fourth switch circuit 50 is turned on. The PWM signal end is pulled down to the ground via the first end of the fourth switch circuit 50 and the second end of the fourth switch circuit 50 to make it a low level, so the fan stops rotating because the driving signal is a low-level signal;

[0064] If the electronic device is in normal operation, the status signal is a high-level signal, which acts on the control end of the third switch circuit 40 to put it in a conducting state. The second DC power supply 500, the third end of the third switch circuit 40, the first end of the third switch circuit 40, the second end of the third switch circuit 40 and the ground form a closed loop, and the first end of the third switch circuit 40 is pulled down to a low level. Therefore, the control end of the fourth switch circuit 50 is also a low-level signal, and the fourth switch circuit 50 is turned off. The PWM signal end of the fan receives the PWM signal sent by the EC, and the fan is controlled by the PWM signal and rotates normally.

[0065] In summary, when the electronic device is in standby or shut down state, the fan control circuit can pull the PWM signal end of the fan down to a low level, so that the fan stops rotating, preventing its control failure, and thus being able to control the fan more accurately.

[0066] See also Figure 4 , Figure 4 is a circuit structure diagram of a fan control circuit provided by an embodiment of the present invention, such as Figure 4 As shown, the first switch module 11 includes a first MOS tube Q1 and a first resistor R1, the voltage divider module 12 includes a second resistor R2 and a third resistor R3, the drain of the first MOS tube Q1 is connected to the first end of the second resistor R2, the source of the first MOS tube Q1 is grounded, the gate of the first MOS tube Q1 is connected to one end of the first resistor R1, and the other end of the first resistor R1 is used to access the state signal SLP_S3#.

[0067] The second end of the second resistor R2 is connected to the control end of the second switch circuit 20 and the first end of the third resistor R3 respectively, and the second end of the third resistor R3 is connected to the first DC power supply 200 and the first end of the second switch circuit 20 respectively.

[0068] The second switch circuit 20 includes a second MOS transistor Q2, a first capacitor C1, and a second capacitor C2. The source of the second MOS transistor Q2 is respectively connected to the second end of the third resistor R3, the first DC power supply 200, and one end of the first capacitor C1, the drain of the second MOS transistor Q2 is connected to the power supply circuit 300 of the fan, the drain of the second MOS transistor Q2 is used to output the power supply 400 of the fan, the gate of the second MOS transistor Q2 is respectively connected to the other end of the first capacitor C1, one end of the second capacitor C2, the second end of the second resistor R2, and the first end of the third resistor R3, and the other end of the second capacitor C2 is grounded.

[0069] The first resistor R1 is used for current limiting and protecting the gate of the first MOS transistor Q1. The first capacitor C1 and the second capacitor C2 are used for protecting the second MOS transistor Q2 and preventing overshoot from burning the second MOS transistor Q2.

[0070] In some embodiments, the first switch circuit 10 further includes a first suppression capacitor C3 connected between the gate of the first MOS transistor Q1 and ground. The first suppression capacitor C3 is used to suppress the Miller effect of the first MOS transistor Q1.

[0071] In some embodiments, the fan control circuit 100 further includes a first filter capacitor C4, a second filter capacitor C5 and a third filter capacitor C6, wherein the first filter capacitor C4 is connected between the source of the second MOS tube Q2 and the ground, the second filter capacitor C5 is connected between the drain of the second MOS tube Q2 and the ground, the second filter capacitor C5 and the third filter capacitor C6 are connected in parallel, and the first filter capacitor C4, the second filter capacitor C5 and the third filter capacitor C6 are all used to achieve filtering.

[0072] The voltage of the first DC power supply 200 can be set as required, and can be the voltage of the power supply 400 of the fan. In the embodiment of the present invention, the voltage is 12V.

[0073] Combination Figure 4 , the working principle of the fan control circuit 100 can be described as follows:

[0074] When the electronic device is in shutdown or standby state, the state signal SLP_S3# of the electronic device is a low level signal, the first MOS transistor Q1 is turned off, the second MOS transistor Q2 is turned off, the first DC power supply 200 is disconnected from the power supply circuit 300 of the fan, and the fan stops rotating due to power failure to prevent its control failure;

[0075] When the electronic device is in normal working condition, the status signal SLP_S3# of the electronic device is a high-level signal, the first MOS tube Q1 is turned on, the second resistor R2 and the third resistor R3 divide the voltage of the first DC power supply 200, the divided voltage signal acts on the gate of the second MOS tube Q2, the second MOS tube Q2 is turned on, the first DC power supply 200 is connected to the power supply circuit 300 of the fan, and the fan is normally powered.

[0076] In summary, when the electronic device is in standby or shut down state, the fan control circuit can cut off the power supply of the fan to stop it from rotating, thereby preventing its control from failing, and thus being able to control the fan more accurately.

[0077] See also Figure 5 , Figure 5 is a circuit structure diagram of a fan control circuit provided by an embodiment of the present invention, such as Figure 5 As shown, the third switch circuit 40 includes a third MOS transistor Q3, a fourth resistor R4 and a fifth resistor R5, and the fourth switch circuit 50 includes a fourth MOS transistor Q4.

[0078] One end of the fourth resistor R4 is used to access the state signal SLP_S3#, the other end of the fourth resistor R4 is connected to the gate of the third MOS transistor Q3, the source of the third MOS transistor Q3 is grounded, and the drain of the third MOS transistor Q3 is respectively connected to one end of the fifth resistor R5 and the gate of the fourth MOS transistor Q4. The other end of the fifth resistor R5 is connected to the second DC power supply 500, the source of the fourth MOS transistor Q4 is grounded, and the drain of the fourth MOS transistor Q4 is connected to the PWM signal terminal.

[0079] The fourth resistor R4 and the fifth resistor R5 are both used for current limiting to prevent the third MOS transistor Q3 and the fourth MOS transistor Q4 from being damaged due to excessive current.

[0080] In some embodiments, the third switch circuit 40 further includes a third suppression capacitor C7, which is connected between the gate of the third MOS transistor Q3 and ground. The third suppression capacitor C7 is used to suppress the Miller effect of the third MOS transistor Q3.

[0081] The voltage of the second DC power supply 500 can be set as required, and can be the voltage of the power supply 400 of the fan. In the embodiment of the present invention, the voltage is 12V.

[0082] Combination Figure 5 , the working principle of the fan control circuit 100 can be described as follows:

[0083] When the electronic device is in shutdown or standby state, the state signal SLP_S3# of the electronic device is a low level signal, the third MOS tube Q3 is cut off, the second DC power supply 500 acts on the gate of the fourth MOS tube Q4, the fourth MOS tube Q4 is turned on, the PWM signal end is pulled down to the ground, the PWM signal is always at a low level, and the fan stops rotating because the driving signal is at a low level, thereby preventing its control failure;

[0084] When the electronic device is in normal working condition, the status signal SLP_S3# of the electronic device is a high level signal, the third MOS tube Q3 is turned on, the gate of the fourth MOS tube Q4 is pulled down to the ground, the fourth MOS tube Q4 is turned off, the PWM signal end normally receives the PWM signal sent by the EC of the electronic device, and the fan is controlled by the PWM signal and works normally.

[0085] In summary, when the electronic device is in standby or shut down state, the fan control circuit can pull the PWM signal end of the fan down to a low level, so that the fan stops rotating, preventing its control failure, and thus being able to control the fan more accurately.

[0086] See also Figure 6 , Figure 6is a schematic diagram of a circuit structure of a power selection circuit provided by an embodiment of the present invention, such as Figure 6 As shown, the power selection circuit 30 includes a sixth resistor R6, a seventh resistor R7, a first switch K1 and a controller U1. One end of the sixth resistor R6 and one end of the seventh resistor R7 are commonly connected to the power supply circuit 300 of the fan. The other end of the sixth resistor R6 is connected to the first contact of the first switch K1, the other end of the seventh resistor R7 is connected to the second contact of the first switch K1, the control end of the first switch K1 is connected to the controller U1, the common end of the first switch K1 is connected to the power supply 400 of the fan, and the controller U1 is used to control the working state of the first switch K1 according to the power supply 400 of the fan.

[0087] If the power supply 400 of the fan is the first power supply, the controller U1 controls the common end of the first switch K1 to be connected to the first contact, so that the other end of the sixth resistor R6 is connected to the power supply 400 of the fan, and controls the other end of the seventh resistor R7 to be disconnected from the power supply 400 of the fan, so that the first power supply supplies power to the fan via the power supply circuit 300 of the fan;

[0088] If the power supply 400 of the fan is the second power supply, the controller U1 controls the common end of the first switch K1 to be connected to the second contact, so that the other end of the sixth resistor R6 is disconnected from the power supply 400 of the fan, and controls the other end of the seventh resistor R7 to establish a connection with the power supply 400 of the fan, so that the second power supply supplies power to the fan via the power supply circuit 300 of the fan.

[0089] The first power supply and the second power supply are determined according to the model of the fan. In the embodiment of the present invention, the voltage of the first power supply may be 12V, and the voltage of the second power supply may be 5V.

[0090] The controller U1 can be implemented by a controller inside the fan or by an external controller. In some embodiments, the controller U1 can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a single-chip microcomputer, an ARM (Acorn RISC Machine) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination of these components. In addition, the controller U1 can also be any traditional processor, controller, microcontroller or state machine. The controller U1 can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP and / or any other such configuration.

[0091] In summary, when the electronic device is in standby or shut down state, the fan control circuit can cut off the power supply of the fan or make the driving signal of the fan to a low level, so that it stops rotating and prevents its control from failing, thereby being able to control the fan more accurately.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A fan control circuit, applied to a fan, characterized in that: The fan is used to dissipate heat for the electronic equipment, and the fan control circuit includes: a first switch circuit and a second switch circuit; The control end of the first switch circuit is used to access the state signal of the electronic device, the first end of the first switch circuit is connected to the control end of the second switch circuit, the second end of the first switch circuit is grounded, the third end of the first switch circuit is respectively connected to the first end of the second switch circuit and the first DC power supply, and the first switch circuit is used to control the working state of the second switch circuit; The second end of the second switch circuit is connected to the power supply circuit of the fan, and the second switch circuit is used to control the connection state between the first DC power supply and the power supply circuit of the fan; The fan control circuit further includes a third switch circuit and a fourth switch circuit; The control end of the third switch circuit is used to access the state signal, the first end of the third switch circuit is connected to the control end of the fourth switch circuit, the second end of the third switch circuit is grounded, the third end of the third switch circuit is connected to the second DC power supply, and the third switch circuit is used to control the working state of the fourth switch circuit; A first end of the fourth switch circuit is connected to a PWM signal end, the PWM signal end is used to receive a PWM signal, the PWM signal is a driving signal of the fan, a second end of the fourth switch circuit is grounded, and the fourth switch circuit is used to control the PWM signal to drive the fan; When the electronic device is in shutdown or standby state, the state signal controls the third switch circuit to be in an off state and the fourth switch circuit to be in an on state, so that the PWM signal end is pulled down to a low level, and then the fan stops rotating.

2. The fan control circuit according to claim 1, characterized in that: The first switch circuit includes a first switch module and a voltage divider module; The control end of the first switch module is used to access the state signal, the first end of the first switch module is connected to the first end of the voltage divider module, and the second end of the first switch module is grounded; The second end of the voltage divider module is connected to the control end of the second switch circuit, and the third end of the voltage divider module is connected to the first DC power supply and the first end of the second switch circuit respectively.

3. The fan control circuit according to claim 2, characterized in that: The first switch module includes a first MOS tube and a first resistor, the voltage divider module includes a second resistor and a third resistor, the drain of the first MOS tube is connected to the first end of the second resistor, the source of the first MOS tube is grounded, the gate of the first MOS tube is connected to one end of the first resistor, and the other end of the first resistor is used to access the state signal; The second end of the second resistor is connected to the control end of the second switch circuit and the first end of the third resistor respectively, and the second end of the third resistor is connected to the first DC power supply and the first end of the second switch circuit respectively.

4. The fan control circuit according to claim 3, characterized in that: The second switch circuit includes a second MOS tube, a first capacitor and a second capacitor; The source of the second MOS tube is respectively connected to the second end of the third resistor, the first DC power supply and one end of the first capacitor, the drain of the second MOS tube is connected to the power supply circuit of the fan, the gate of the second MOS tube is respectively connected to the other end of the first capacitor, one end of the second capacitor, the second end of the second resistor and the first end of the third resistor, and the other end of the second capacitor is grounded.

5. The fan control circuit according to claim 1, characterized in that: The third switch circuit includes a third MOS tube, a fourth resistor and a fifth resistor, and the fourth switch circuit includes a fourth MOS tube; One end of the fourth resistor is used to access the state signal, the other end of the fourth resistor is connected to the gate of the third MOS transistor, the source of the third MOS transistor is grounded, and the drain of the third MOS transistor is respectively connected to one end of the fifth resistor and the gate of the fourth MOS transistor; The other end of the fifth resistor is connected to the second DC power supply, the source of the fourth MOS tube is grounded, and the drain of the fourth MOS tube is connected to the PWM signal end.

6. The fan control circuit according to any one of claims 1 to 5, characterized in that: It also includes a power selection circuit, one end of which is connected to the power supply of the fan, and the other end of which is connected to the power supply circuit of the fan. The power selection circuit is used to select a corresponding adapter circuit according to the power supply of the fan.

7. The fan control circuit according to claim 6, characterized in that: The power selection circuit includes a sixth resistor, a seventh resistor, a first switch and a controller; One end of the sixth resistor and one end of the seventh resistor are commonly connected to a power supply circuit of the fan; The other end of the sixth resistor is connected to the first contact of the first switch, the other end of the seventh resistor is connected to the second contact of the first switch, the control end of the first switch is connected to the controller, the common end of the first switch is connected to the power supply of the fan, and the controller is used to control the working state of the first switch according to the power supply of the fan.

8. A fan, characterized in that: The fan comprises the fan control circuit as claimed in any one of claims 1 to 7, and the fan is used to dissipate heat for electronic equipment.

9. An electronic device, characterized in that: The electronic device comprises the fan according to claim 8.

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