Speed-adjustable fan control circuit

Abstract

The utility model provides a speed-adjustable fan control circuit which comprises a speed regulation controller and a fan speed regulation circuit, the speed regulation controller comprises a start-stop control pin, a power supply output pin, a speed regulation feedback pin and a speed regulation output pin, a start-stop control pin of the speed regulation controller is respectively connected to a fan start-stop signal input end and a power supply end of the fan, and a power supply output pin of the speed regulation controller is connected to a power supply end of a fan speed regulation circuit; a speed regulation output pin of the speed regulation controller is respectively connected to an input end of the fan speed regulation circuit and a speed regulation signal input end of the fan, and a speed regulation feedback pin of the speed regulation controller is connected to an output end of the fan speed regulation circuit. And the speed of the fan is automatically regulated and controlled through the speed regulation controller, so that the circuit stability is improved while the cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of fan speed regulation, and in particular to a speed-adjustable fan control circuit. Background Art

[0002] In power supply design, adjustable speed fans are commonly used heat dissipation components. However, in the prior art, the CPU is usually used to control the speed of the fan. If the ambient temperature of the fan is taken into consideration, complex control logic needs to be integrated into the CPU in advance, which not only requires certain professional skills from developers, but also increases the control cost. Utility Model Content

[0003] In view of this, the purpose of the present application is to at least provide an adjustable speed fan control circuit, which automatically controls the fan speed through a speed controller, thereby reducing costs and improving circuit stability.

[0004] This application mainly includes the following aspects:

[0005] In a first aspect, an embodiment of the present application provides an adjustable speed fan control circuit, which includes a speed controller and a fan speed control circuit, wherein the speed controller includes a start / stop control pin, a power output pin, a speed control feedback pin and a speed control output pin, wherein the start / stop control pin of the speed controller is respectively connected to the fan start / stop signal input terminal and the fan power supply terminal, and the power output pin of the speed controller is connected to the power supply terminal of the fan speed control circuit; the speed control output pin of the speed controller is respectively connected to the input terminal of the fan speed control circuit and the speed control signal input terminal of the fan, and the speed control feedback pin of the speed controller is connected to the output terminal of the fan speed control circuit.

[0006] In one possible implementation, the fan speed control circuit includes a temperature signal acquisition module, a duty cycle signal acquisition module and an adder module, wherein one end of the temperature signal acquisition module is connected to the power output pin of the speed controller, and the other end of the temperature signal acquisition module is connected to the input end of the adder module; one end of the duty cycle signal acquisition module is respectively connected to the speed control signal input end of the fan and the speed control output pin of the speed controller, and the other end of the duty cycle signal acquisition module is connected to the input end of the adder module; the output end of the adder module is connected to the speed control feedback pin of the speed controller.

[0007] In one possible implementation, the adder module includes a first follower, a first resistor and a second resistor, wherein the positive input end of the first follower is respectively connected to the other end of the temperature signal acquisition module and the other end of the duty cycle signal acquisition module, the negative input end of the first follower is respectively connected to one end of the first resistor and one end of the second resistor, the other end of the first resistor is connected to the output end of the first follower and then connected to the speed feedback pin of the speed controller, and the other end of the second resistor is grounded.

[0008] In one possible implementation, the temperature signal acquisition module includes a third resistor, a fourth resistor, a second follower and a fifth resistor, wherein one end of the third resistor is connected to the power output pin of the speed controller, the other end of the third resistor is respectively connected to the positive input end of the second follower and one end of the fourth resistor, the other end of the fourth resistor is grounded, the negative input end of the second follower is connected to the output end of the second follower and then connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the positive input end of the first follower, and the fourth resistor is a thermistor.

[0009] In one possible implementation, the duty cycle signal acquisition module includes a sixth resistor, a seventh resistor, an eighth resistor, a first capacitor and a third follower, wherein one end of the sixth resistor is respectively connected to the speed control output pin of the speed controller and the speed control signal input end of the fan, the other end of the sixth resistor is respectively connected to one end of the first capacitor, one end of the seventh resistor and the positive input end of the third follower, the first capacitor and the other end and the other end of the seventh resistor are grounded, the negative input end of the third follower is connected to the output end of the third follower and then connected to one end of the eighth resistor, and the other end of the eighth resistor is connected to the positive input end of the first follower.

[0010] In one possible implementation, the adjustable speed fan control circuit also includes a ninth resistor, a tenth resistor and an anti-reverse diode, wherein one end of the ninth resistor is connected to a speed control output pin of the speed control controller, the other end of the ninth resistor is respectively connected to one end of the tenth resistor, the cathode of the anti-reverse diode, one end of the sixth resistor and the speed control signal input end of the fan, and the anode of the anti-reverse diode and the other end of the tenth resistor are both grounded.

[0011] In one possible implementation, the adjustable speed fan control circuit also includes an eleventh resistor and a second capacitor, and the speed controller also includes a compensation pin, wherein one end of the eleventh resistor is connected to the output end of the first follower, the other end of the eleventh resistor is connected to one end of the second capacitor, and the other end of the second capacitor is connected to the compensation pin.

[0012] In one possible implementation, the adjustable speed fan control circuit also includes a fan start and stop control circuit and a fan fault detection circuit, and the speed controller also includes a fault detection pin, wherein the input end of the fan start and stop control circuit is connected to the fan start and stop signal input end, and the output end of the fan start and stop control circuit is respectively connected to the start and stop control pin of the speed controller and the power supply end of the fan; the first input end of the fan fault detection circuit is connected to the fault detection pin, the second input end of the fan fault detection circuit is connected to the fault signal output end of the fan, and the output end of the fan fault detection circuit is connected to the fault feedback signal end.

[0013] In one possible implementation, the fan start and stop control circuit includes a third capacitor, a twelfth resistor, a thirteenth resistor, a first control switch and a second control switch, wherein one end of the third capacitor is respectively connected to a power supply, one end of the twelfth resistor and a first connection end of the first control switch, the other end of the third capacitor is grounded, the other end of the twelfth resistor is respectively connected to the control end of the first control switch and the first connection end of the second control switch, the second connection end of the first control switch is respectively connected to the power supply end of the fan and the start and stop control pin of the speed controller; one end of the thirteenth resistor is connected to the fan start and stop signal input end, the other end of the thirteenth resistor is connected to the control end of the second control switch, and the second connection end of the second control switch is grounded.

[0014] In a possible implementation manner, the fan fault detection circuit includes a comparator, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a fourth capacitor and a third control switch, wherein one end of the fourteenth resistor is connected to the fault signal output end of the fan, the other end of the fourteenth resistor is connected to the control end of the third control switch, the first connection end of the third control switch is connected to one end of the fifteenth resistor, the second connection end of the third control switch is grounded, the other end of the fifteenth resistor is respectively connected to one end of the sixteenth resistor, one end of the fourth capacitor, one end of the seventeenth resistor, the positive input end of the comparator and the fault detection pin, the other end of the sixteenth resistor and the other end of the fourth capacitor are grounded, and the other end of the seventeenth resistor is connected to the power output pin of the speed controller; the negative input end of the comparator is respectively connected to one end of the eighteenth resistor, one end of the nineteenth resistor and one end of the twentieth resistor, the other end of the eighteenth resistor is connected to the power output pin of the speed controller, the other end of the nineteenth resistor is grounded, and the other end of the twentieth resistor is connected to the output end of the comparator and then connected to the fault feedback signal end.

[0015] In one possible implementation, the speed controller also includes an oscillation signal input pin and a ground pin, and the adjustable speed fan control circuit also includes a twenty-first resistor and a fifth capacitor, wherein one end of the twenty-first resistor is connected to the power output pin of the speed controller, the other end of the twenty-first resistor is respectively connected to the oscillation signal input pin and one end of the fifth capacitor, and the other end of the fifth capacitor is grounded; the ground pin of the speed controller is grounded.

[0016] The adjustable speed fan control circuit provided by the embodiment of the present application includes a speed controller and a fan speed control circuit, and the speed controller includes a start-stop control pin, a power output pin, a speed control feedback pin and a speed control output pin, wherein the start-stop control pin of the speed controller is respectively connected to the fan start-stop signal input terminal and the fan power supply terminal, and the power output pin of the speed controller is connected to the power supply terminal of the fan speed control circuit; the speed control output pin of the speed controller is respectively connected to the input terminal of the fan speed control circuit and the speed control signal input terminal of the fan, and the speed control feedback pin of the speed controller is connected to the output terminal of the fan speed control circuit. The speed controller is used to automatically control the fan speed, thereby reducing costs and improving circuit stability.

[0017] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 One of the structural schematic diagrams of an adjustable speed fan control circuit provided in an embodiment of the present application is shown;

[0020] Figure 2 A second structural schematic diagram of a speed-adjustable fan control circuit provided in an embodiment of the present application is shown;

[0021] Figure 3 A third structural schematic diagram of an adjustable speed fan control circuit provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0022] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of explanation and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn in real proportion. The flowchart used in this application shows the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowchart can be implemented out of sequence, and the steps without logical context can be reversed in order or implemented simultaneously. In addition, those skilled in the art, under the guidance of the content of the present application, can add one or more other operations to the flowchart, or remove one or more operations from the flowchart.

[0023] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0024] In power supply design, adjustable speed fans are commonly used heat dissipation components. However, in the prior art, the CPU is usually used to control the speed of the fan. If the ambient temperature of the fan is taken into consideration, complex control logic needs to be integrated into the CPU in advance, which not only requires certain professional skills from developers, but also increases the control cost.

[0025] Based on this, the embodiment of the present application provides an adjustable speed fan control circuit, which automatically controls the fan speed through a speed controller, thereby reducing costs and improving circuit stability, as follows:

[0026] See also Figure 1 , Figure 1 FIG. 1 shows one of the structural schematic diagrams of a speed-adjustable fan control circuit provided in an embodiment of the present application. Figure 1 As shown, the adjustable speed fan control circuit provided in the embodiment of the present application includes: a speed controller U1 and a fan speed control circuit 2, the speed controller includes a start-stop control pin VDD, a power output pin Vref, a speed feedback pin FB and a speed output pin OUT, specifically, the speed controller U1 can select a PWM speed control chip of the UCCx8C4x series, for example, a UCC28C42 chip can be selected, and the output voltage of the power output pin Vref is 5Vref.

[0027] In a preferred embodiment, the start / stop control pin VDD of the speed controller U1 is respectively connected to the fan start / stop signal input terminal J1-VIN and the fan power supply terminal J2-VIN, and the power output pin Vref of the speed controller U1 is connected to the power supply terminal VCC_IN of the fan speed control circuit 2.

[0028] The speed control output pin OUT of the speed control controller U1 is respectively connected to the input end of the fan speed control circuit 2 and the speed control signal input end J2-PWM of the fan, and the speed control feedback pin FB of the speed control controller U1 is connected to the output end of the fan speed control circuit 2.

[0029] Among them, the fan start and stop signal input terminal J1-VIN is integrated on the first socket J1, the fan power supply terminal J2-VIN and the fan speed control signal input terminal J2-PWM are integrated on the second socket J2, and the fan start and stop signal input terminal J1-VIN provides a power supply voltage VCC to the start and stop control pin VDD of the speed controller U1 and the power supply terminal VCC_IN of the fan speed control circuit 2.

[0030] See also Figure 2 , Figure 2 FIG2 shows a second structural diagram of a speed-adjustable fan control circuit provided in an embodiment of the present application. Figure 2 As shown, the fan speed regulation circuit 2 includes a temperature signal acquisition module 21 , a duty cycle signal acquisition module 22 and an adder module 23 .

[0031] In a preferred embodiment, one end of the temperature signal acquisition module 21 is connected to the power output pin Vref of the speed controller U1, the other end of the temperature signal acquisition module 21 is connected to the input end of the adder module 23, one end of the duty cycle signal acquisition module 22 is respectively connected to the speed control signal input end J2-PWM of the fan and the speed control output pin OUT of the speed controller U1, the other end of the duty cycle signal acquisition module 22 is connected to the input end of the adder module 23, and the output end of the adder module 23 is connected to the speed control feedback pin FB of the speed controller U1.

[0032] See also Figure 3 , Figure 3 FIG3 shows a third structural diagram of a speed-adjustable fan control circuit provided in an embodiment of the present application. Figure 3 As shown, the adder module 23 includes a first follower U2A, a first resistor R1 and a second resistor R2, the temperature signal acquisition module 21 includes a third resistor R3, a fourth resistor R4, a second follower U2B and a fifth resistor R5, and the duty cycle signal acquisition module 22 includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a first capacitor C1 and a third follower U2C.

[0033] The speed-adjustable fan control circuit further includes a ninth resistor R9, a tenth resistor R10 and an anti-reverse diode D1.

[0034] One end of the third resistor R3 is connected to the power output pin Vref of the speed controller U1, the other end of the third resistor R3 is respectively connected to the positive input end of the second follower U2B and one end of the fourth resistor R4, the other end of the fourth resistor R4 is grounded, the negative input end of the second follower U2B is connected to the output end of the second follower U2B and then connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is connected to the positive input end of the first follower U2A, and the fourth resistor R4 is a thermistor.

[0035] Among them, one end of the ninth resistor is connected to the speed control output pin OUT of the speed control controller U1, and the other end of the ninth resistor R9 is respectively connected to one end of the tenth resistor R10, the cathode of the anti-reverse diode D1, one end of the sixth resistor R6 and the speed control signal input terminal J2-PWM of the fan, and the anode of the anti-reverse diode D1 and the other end of the tenth resistor R10 are both grounded.

[0036] The other end of the sixth resistor R6 is respectively connected to one end of the first capacitor C1, one end of the seventh resistor R7 and the positive input end of the third follower U2C. The first capacitor C1 and the other end and the other end of the seventh resistor R7 are grounded. The negative input end of the third follower U2C is connected to the output end of the third follower U2C and then connected to one end of the eighth resistor R8. The other end of the eighth resistor R8 is connected to the positive input end of the first follower U2A.

[0037] A negative input terminal of the first follower U2A is connected to one end of the first resistor R1 and one end of the second resistor R2 respectively, and the other end of the second resistor R2 is grounded.

[0038] In another preferred embodiment, the adjustable speed fan control circuit further includes an eleventh resistor R11 and a second capacitor C2, and the speed controller U1 further includes a compensation pin COMP.

[0039] One end of the eleventh resistor R11 is connected to the output end of the first follower U2A, the other end of the eleventh resistor R11 is connected to one end of the second capacitor C2, and the other end of the second capacitor C2 is connected to the compensation pin COMP.

[0040] return Figure 2 In a preferred embodiment, the adjustable speed fan control circuit further includes a fan start / stop control circuit 3 and a fan fault detection circuit 4, and the speed controller U1 further includes a fault detection pin CS.

[0041] The input end of the fan start-stop control circuit 3 is connected to the fan start-stop signal input end J1-VIN, and the output end of the fan start-stop control circuit 3 is respectively connected to the start-stop control pin VDD of the speed controller U1 and the power supply end J2-VIN of the fan.

[0042] The first input end of the fan fault detection circuit 4 is connected to the fault detection pin CS, the second input end of the fan fault detection circuit 4 is connected to the fault signal output end J2-WB of the fan, the output end of the fan fault detection circuit 4 is connected to the fault feedback signal end FAULT, and the fault signal output end J2-WB is integrated on the second socket J2.

[0043] return Figure 3 The fan start / stop control circuit 3 includes a third capacitor C3, a twelfth resistor R12, a thirteenth resistor R13, a first control switch Q1 and a second control switch Q2.

[0044] Among them, one end of the third capacitor C3 is respectively connected to the power supply +12V, one end of the twelfth resistor R12 and the first connection end of the first control switch Q1, the other end of the third capacitor C3 is grounded, the other end of the twelfth resistor R12 is respectively connected to the control end of the first control switch Q1 and the first connection end of the second control switch Q2, and the second connection end of the first control switch Q1 is respectively connected to the power supply end J2-VIN of the fan and the start-stop control pin VDD of the speed controller U1.

[0045] One end of the thirteenth resistor R13 is connected to the fan start / stop signal input terminal J1 -VIN, the other end of the thirteenth resistor R13 is connected to the control end of the second control switch Q2, and the second connection end of the second control switch Q2 is grounded.

[0046] In another preferred embodiment, the fan fault detection circuit 4 includes a comparator U2D, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a twentieth resistor R20, a fourth capacitor C4 and a third control switch Q3.

[0047] Among them, one end of the fourteenth resistor R14 is connected to the fault signal output terminal J2-WB of the fan, the other end of the fourteenth resistor R14 is connected to the control end of the third control switch Q3, the first connection end of the third control switch Q3 is connected to one end of the fifteenth resistor R15, the second connection end of the third control switch Q3 is grounded, the other end of the fifteenth resistor R15 is respectively connected to one end of the sixteenth resistor R16, one end of the fourth capacitor C4, one end of the seventeenth resistor R17, the positive input end of the comparator U2D and the fault detection pin CS, the other end of the sixteenth resistor R16 and the other end of the fourth capacitor C4 are grounded, and the other end of the seventeenth resistor R17 is connected to the power output pin Vref of the speed controller U1.

[0048] The negative input terminal of the comparator U2D is respectively connected to one end of the eighteenth resistor R18, one end of the nineteenth resistor R19 and one end of the twentieth resistor R20, the other end of the eighteenth resistor R18 is connected to the power output pin Vref of the speed controller U1, the other end of the nineteenth resistor R19 is grounded, the other end of the twentieth resistor R20 is connected to the output terminal of the comparator U2D and then connected to the fault feedback signal terminal FAULT, and the fault feedback signal terminal FAULT is integrated in the first socket.

[0049] In a preferred embodiment, the speed controller U1 also includes an oscillation signal input pin RTCT and a ground pin GND, and the adjustable speed fan control circuit also includes a twenty-first resistor R21 and a fifth capacitor C5, wherein one end of the twenty-first resistor R21 is connected to the power output pin RTCT of the speed controller U1, and the other end of the twenty-first resistor R21 is respectively connected to the oscillation signal input pin RTCT and one end of the fifth capacitor C5, the other end of the fifth capacitor C5 is grounded, and the ground pin GND of the speed controller is grounded.

[0050] In a specific embodiment, R1, R2, R5, R8 and R3 can be selected from 10K, the first controller Q1 can be selected from a PNP transistor or a PMOS, and the second controller Q2 and the third controller Q3 can be selected from NMOS. When the first controller Q1 is selected from a PNP transistor, the control end of the first controller Q1 is the base of the PNP transistor, the first connection end of the first controller Q1 is the emitter of the PNP transistor, and the second connection end of the first controller Q1 is the collector of the PNP transistor. When the second controller Q1 is selected from an NMOS, the control end of the second controller Q2 is the gate of the NMOS, the first connection end of the second controller Q2 is the drain of the NMOS, and the second connection end of the second controller Q2 is the source of the NMOS. When the third controller Q3 is selected from an NMOS, the control end of the third controller Q3 is the gate of the NMOS, the first connection end of the third controller Q3 is the drain of the NMOS, and the second connection end of the third controller Q3 is the source of the NMOS.

[0051] In the present application, the first socket J1 is an input signal socket, the second socket J2 is an output signal socket, the second socket J2 is connected to an adjustable speed fan, and U2A, U2B, U2C and U2D are operational amplifiers.

[0052] The first socket J1 includes a power line connection terminal (connected to a +12V power supply), a ground terminal GND, a fan start / stop signal input terminal J1-VIN and a fault feedback signal terminal FAULT.

[0053] The second socket J2 includes a power supply terminal J2-VIN connected to the fan, a ground terminal GND, a speed regulation signal input terminal J2-PWM, and a fault signal output terminal J2-WB.

[0054] Before the adjustable speed fan control circuit is operated, the parameter values ​​of the twenty-first resistor R21 and the fifth capacitor C4 connected to the RTCT pin of the speed controller U1 are configured first, and the oscillation period is set to the PWM frequency 25KHz required for fan speed regulation.

[0055] The adjustable speed fan control circuit provided in this application has the following working process:

[0056] A1. When the fan is in the normal shutdown state, the fan start / stop signal input terminal J1-VIN = 0V. At this time, the state of the entire adjustable speed fan control circuit is as follows:

[0057] The first control switch Q1 and the second control switch Q2 both remain in the off state, the fan start-stop control circuit provides a power supply voltage VCC=0V to U1 and the fan, the speed controller U1 remains in the off state, the input signal corresponding to the speed control signal input terminal J2-PWM in the second socket J2 is 0, and the fan will not start.

[0058] A2. Apply a high level (≥5V) to the fan start / stop signal input terminal J1-VIN to start the fan. At this time, the status of the entire adjustable speed fan control circuit is as follows:

[0059] ① The driving voltage corresponding to the fan start-stop signal input terminal J1-VIN passes through the thirteenth resistor R13 to the G pole of the second control switch Q2, the second control switch Q2 is turned on, and the first control switch Q1 is then turned on, and the fan start-stop control circuit provides a power supply voltage VCC=12V to U1 and the fan;

[0060] ② The start / stop control pin VDD of the speed controller U1 receives the power supply 12V, the speed controller U1 starts, and the power output pin Vref outputs a voltage of 5Vref=5.0V;

[0061] ③ The fourth resistor R4 (10KΩ at 25°C) and the third resistor R3 are connected in series, and under the power supply of 5Vref (5V), a voltage division value is formed, and the voltage division value is sent to the positive input terminal of the first follower U2A through the second follower U2B as one of the positive inputs of the first follower U2A;

[0062] ④ The speed control output pin OUT of the speed control controller U1 generates an output pulse with a certain duty cycle, and the pulse amplitude is 12V. The pulse is divided to 5V by the ninth resistor R9 and the tenth resistor R10. The anti-reverse diode D1 (TVS tube) further prevents the output corresponding to the speed control output pin OUT of the speed control controller U1 from exceeding 5V. When the speed control output pin OUT outputs a pulse to the speed control signal input terminal J2-PWM in the second socket J2, the output pulse is also filtered to a voltage range of 0-2.5V by the sixth resistor R6, the seventh resistor R7 and the first capacitor C1, and then sent to the positive input terminal of the first follower U2A through the third follower U2C as the second positive input of the first follower U2A;

[0063] ⑤ The output voltage Uadd of the first follower U2A is equal to the sum of the voltage value Ut output by the temperature signal acquisition module and the voltage value Upwm output by the duty cycle signal acquisition module, that is, Uadd=Ut+Upwm;

[0064] ⑥ Look up the temperature resistance table and get Ut_25°=2.5V, Ut_45°=1.666V, Ut_60°=1.121V, Ut_70°=0.872V, Ut_80°=0.678V, Ut_90°=0.529V. Taking Ut_25° as an example, Ut_25°=2.5V, which means that when the corresponding acquisition value of the fourth resistor is 25°, the voltage value Ut output by the temperature signal acquisition module;

[0065] ⑦After the voltage signal output from the speed control output pin OUT is divided by the sixth resistor R6 and the seventh resistor R7, the obtained Upwm is 0.32 times of 5V, that is, when Ut_70°=0.872V, the PWM output is set at a temperature of 70℃ and the full waveform is 100%, then Upwm=5.0V×0.32=1.62V, Uadd=0.872V+1.62V, that is, Uadd=2.5V, which is exactly the feedback point setting voltage of the speed control controller U1. At this time, the PWM duty cycle output by the speed control controller U1 is 100%, that is, the fan runs at full speed;

[0066] ⑧ When the temperature does not reach 70℃, the Ut voltage gradually decreases from 2.5V, accompanied by the gradual increase of Upwm from 0V, that is, the duty cycle gradually increases, and the fan speed also gradually increases with the increase of temperature.

[0067] A3. Fault detection:

[0068] When the CS pin voltage of the controller U1 is higher than 1V, the speed controller U1 will block the pulse output of the OUT pin. Using this feature, the fan fault detection circuit in this application detects faults as follows:

[0069] ① When the speed controller U1 is initially powered on, when the fan rotates normally, because the capacitance of the fourth capacitor C4 is relatively large, 5Vref charges the fourth capacitor C4 through the seventeenth resistor R17, and the charging time is relatively long. When the pulse output PWM signal of the speed controller U1 is generated, the fault signal output terminal J2-WB of the fan has a feedback pulse with an amplitude of 5V and a duty cycle of 50%, causing the third control switch Q3 to be turned on during the high level period of the PWM pulse, so that the voltage on the fourth capacitor C4 will be released by the third control switch Q3. The fifteenth resistor R15 is a discharge limiting current resistor. In this way, when the speed controller U1 has a normal pulse output, the voltage on the fourth capacitor C4 cannot be greater than 1V, so the CS signal cannot cause pulse blocking. The voltage divider ratio formed by R18 and R19 sets the negative input terminal of the comparator U2D to 1V. When the fault does not occur, the comparator U2D outputs a low level signal because the CS voltage does not exceed 1V, indicating that the fan has not failed.

[0070] ② When the fan is blocked or encounters other faults, there is no pulse output from the fault signal output terminal J2-WB of the fan, and the third control switch Q3 cannot receive pulses. The voltage on the fourth capacitor C4 gradually increases. After exceeding 1V, the output pulse of the speed controller U1 is blocked. When a fault occurs, the comparator U2D flips because the CS voltage exceeds 1V, and the output signal FAULT becomes a high level, indicating a fan fault.

[0071] The adjustable speed fan control circuit provided in the present application can autonomously control the operation and feedback of the fan in a closed loop, and the speed and temperature detection are linked to automatically adjust the fan speed and automatically protect when a fault occurs. Therefore, the adjustable speed fan control circuit provided in the present application is very practical.

[0072] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. In the several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0073] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0074] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0075] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., various media that can store program codes.

[0076] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A speed-adjustable fan control circuit, characterized in that: The adjustable speed fan control circuit includes a speed controller and a fan speed control circuit, wherein the speed controller includes a start / stop control pin, a power output pin, a speed feedback pin and a speed output pin. The start / stop control pins of the speed controller are respectively connected to the fan start / stop signal input terminal and the fan power supply terminal, and the power supply output pin of the speed controller is connected to the power supply terminal of the fan speed control circuit; The speed control output pin of the speed control controller is respectively connected to the input end of the fan speed control circuit and the speed control signal input end of the fan, and the speed control feedback pin of the speed control controller is connected to the output end of the fan speed control circuit.

2. The adjustable speed fan control circuit according to claim 1, characterized in that: The fan speed control circuit includes a temperature signal acquisition module, a duty cycle signal acquisition module and an adder module. Wherein, one end of the temperature signal acquisition module is connected to the power output pin of the speed controller, and the other end of the temperature signal acquisition module is connected to the input end of the adder module; One end of the duty cycle signal acquisition module is connected to the speed control signal input end of the fan and the speed control output pin of the speed control controller, and the other end of the duty cycle signal acquisition module is connected to the input end of the adder module; The output end of the adder module is connected to the speed feedback pin of the speed controller.

3. The adjustable speed fan control circuit according to claim 2, characterized in that: The adder module includes a first follower, a first resistor and a second resistor. Among them, the positive input end of the first follower is respectively connected to the other end of the temperature signal acquisition module and the other end of the duty cycle signal acquisition module, the negative input end of the first follower is respectively connected to one end of the first resistor and one end of the second resistor, the other end of the first resistor is connected to the output end of the first follower and then connected to the speed feedback pin of the speed controller, and the other end of the second resistor is grounded.

4. The adjustable speed fan control circuit according to claim 3, characterized in that: The temperature signal acquisition module includes a third resistor, a fourth resistor, a second follower and a fifth resistor. Among them, one end of the third resistor is connected to the power output pin of the speed controller, the other end of the third resistor is respectively connected to the positive input end of the second follower and one end of the fourth resistor, the other end of the fourth resistor is grounded, the negative input end of the second follower is connected to the output end of the second follower and then connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the positive input end of the first follower, and the fourth resistor is a thermistor.

5. The adjustable speed fan control circuit according to claim 3, characterized in that: The duty cycle signal acquisition module includes a sixth resistor, a seventh resistor, an eighth resistor, a first capacitor and a third follower. Among them, one end of the sixth resistor is respectively connected to the speed control output pin of the speed controller and the speed control signal input end of the fan, the other end of the sixth resistor is respectively connected to one end of the first capacitor, one end of the seventh resistor and the positive input end of the third follower, the first capacitor and the other end and the other end of the seventh resistor are grounded, the negative input end of the third follower is connected to the output end of the third follower and then connected to one end of the eighth resistor, and the other end of the eighth resistor is connected to the positive input end of the first follower.

6. The adjustable speed fan control circuit according to claim 5, characterized in that: The adjustable speed fan control circuit also includes a ninth resistor, a tenth resistor and an anti-reverse diode. Among them, one end of the ninth resistor is connected to the speed control output pin of the speed control controller, and the other end of the ninth resistor is respectively connected to one end of the tenth resistor, the cathode of the anti-reverse diode, one end of the sixth resistor and the speed control signal input end of the fan, and the anode of the anti-reverse diode and the other end of the tenth resistor are both grounded.

7. The adjustable speed fan control circuit according to claim 3, characterized in that: The adjustable speed fan control circuit further includes an eleventh resistor and a second capacitor, and the speed controller further includes a compensation pin. One end of the eleventh resistor is connected to the output end of the first follower, the other end of the eleventh resistor is connected to one end of the second capacitor, and the other end of the second capacitor is connected to the compensation pin.

8. The adjustable speed fan control circuit according to claim 1, characterized in that: The adjustable speed fan control circuit also includes a fan start and stop control circuit and a fan fault detection circuit, and the speed controller also includes a fault detection pin. Wherein, the input end of the fan start-stop control circuit is connected to the fan start-stop signal input end, and the output end of the fan start-stop control circuit is respectively connected to the start-stop control pin of the speed controller and the power supply end of the fan; The first input end of the fan fault detection circuit is connected to the fault detection pin, the second input end of the fan fault detection circuit is connected to the fault signal output end of the fan, and the output end of the fan fault detection circuit is connected to the fault feedback signal end.

9. The adjustable speed fan control circuit according to claim 8, characterized in that: The fan start-stop control circuit includes a third capacitor, a twelfth resistor, a thirteenth resistor, a first control switch and a second control switch. Wherein, one end of the third capacitor is respectively connected to the power supply, one end of the twelfth resistor and the first connection end of the first control switch, the other end of the third capacitor is grounded, the other end of the twelfth resistor is respectively connected to the control end of the first control switch and the first connection end of the second control switch, and the second connection end of the first control switch is respectively connected to the power supply end of the fan and the start / stop control pin of the speed controller; One end of the thirteenth resistor is connected to the fan start / stop signal input end, the other end of the thirteenth resistor is connected to the control end of the second control switch, and the second connection end of the second control switch is grounded.

10. The speed-adjustable fan control circuit according to claim 8, characterized in that: The fan fault detection circuit includes a comparator, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a fourth capacitor and a third control switch. Wherein, one end of the fourteenth resistor is connected to the fault signal output end of the fan, the other end of the fourteenth resistor is connected to the control end of the third control switch, the first connection end of the third control switch is connected to one end of the fifteenth resistor, the second connection end of the third control switch is grounded, the other end of the fifteenth resistor is respectively connected to one end of the sixteenth resistor, one end of the fourth capacitor, one end of the seventeenth resistor, the positive input end of the comparator and the fault detection pin, the other end of the sixteenth resistor and the other end of the fourth capacitor are grounded, and the other end of the seventeenth resistor is connected to the power output pin of the speed controller; The negative input terminal of the comparator is respectively connected to one end of the eighteenth resistor, one end of the nineteenth resistor and one end of the twentieth resistor, the other end of the eighteenth resistor is connected to the power output pin of the speed controller, the other end of the nineteenth resistor is grounded, and the other end of the twentieth resistor is connected to the output terminal of the comparator and then connected to the fault feedback signal terminal.

11. The speed-adjustable fan control circuit according to claim 1, characterized in that: The speed controller further includes an oscillation signal input pin and a ground pin, and the adjustable speed fan control circuit further includes a twenty-first resistor and a fifth capacitor. Wherein, one end of the twenty-first resistor is connected to the power output pin of the speed controller, the other end of the twenty-first resistor is respectively connected to the oscillation signal input pin and one end of the fifth capacitor, and the other end of the fifth capacitor is grounded; The ground pin of the speed controller is grounded.

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