CN214945188U

CN214945188U - Fan rotating speed control circuit, heat dissipation equipment and electronic equipment

Info

Publication number: CN214945188U
Application number: CN202022266310.1U
Authority: CN
Inventors: 谢东桂; 张正德
Original assignee: SHENZHEN ORIENTECH CO Ltd
Current assignee: SHENZHEN ORIENTECH CO Ltd
Priority date: 2020-10-13
Filing date: 2020-10-13
Publication date: 2021-11-30
Anticipated expiration: 2030-10-13

Abstract

The present application relates to a fan speed control circuit, heat dissipation device and electronic device, wherein, this fan includes at speed control circuit: a driving circuit for receiving the fan configuration rotating speed instruction of the main controller and the feedback rotating speed of the fan and outputting a driving voltage; and the amplifying circuit receives and amplifies the driving voltage and outputs an amplified voltage signal to the fan. The drive circuit is connected with the main controller and the fan, and the amplifying circuit is connected with the drive circuit and the fan. The fan rotating speed control circuit receives the fan configuration rotating speed instruction of the main controller and the feedback rotating speed of the fan through the driving circuit, outputs the driving voltage to the amplifying circuit according to the fan configuration rotating speed instruction and the feedback rotating speed of the fan, outputs the amplified driving signal to the fan through the amplifying circuit, controls the rotating speed of the fan, can adjust the rotating speed of the fan according to actual needs, and improves the heat dissipation effect.

Description

Fan rotating speed control circuit, heat dissipation equipment and electronic equipment

Technical Field

The present application relates to the field of control technologies, and in particular, to a fan speed control circuit, a heat dissipation device, and an electronic device.

Background

As is well known, electronic devices generate a certain amount of heat during operation, and heat dissipation is usually required to increase the service life of the electronic devices.

In a conventional method for dissipating heat of an electronic device by using fans, a plurality of fans are disposed inside the electronic device, and fixed dc voltages are respectively set to drive the fans according to the different positions of the fans. However, as the dust is gradually accumulated and the mechanical wear of the fan is increased, the rotation speed of the fan under the condition of the set voltage will be greatly changed, and the expected heat dissipation effect cannot be achieved.

Therefore, the conventional heat dissipation device using a fan to dissipate heat of an electronic device has a disadvantage of poor heat dissipation effect.

SUMMERY OF THE UTILITY MODEL

Accordingly, there is a need for a fan speed control circuit, a heat dissipation device and an electronic device, which can improve the heat dissipation effect.

In a first aspect, a fan speed control circuit is provided, including:

a fan speed control circuit comprising:

a driving circuit for receiving the fan configuration rotating speed instruction of the main controller and the feedback rotating speed of the fan and outputting a driving voltage;

the amplifying circuit receives and amplifies the driving voltage and outputs the amplified driving signal to the fan;

the drive circuit is connected with the main controller and the fan, and the amplifying circuit is connected with the drive circuit and the fan.

In one embodiment, the driving circuit is an IIC control circuit.

In one embodiment, the IIC control circuit includes a control chip, and the control chip is connected to the main controller, the fan, and the amplifying circuit.

In one embodiment, the number of the fans is more than two, and the number of the amplifying circuits is the same as that of the fans; the feedback input end of the control chip is connected with the corresponding fan, and the driving output end of the control chip is connected with the corresponding fan through each amplifying circuit.

In one embodiment, the amplifying circuit comprises an integrating circuit, a voltage amplifying circuit and a current amplifying circuit; the integrating circuit is connected with the driving circuit and the voltage amplifying circuit; the voltage amplifying circuit is connected with the current amplifying circuit and the fan; the current amplifying circuit is connected with a power supply.

In one embodiment, the integration circuit comprises an integration resistor and an integration capacitor;

one end of the integrating resistor is connected with the driving circuit, and the other end of the integrating resistor is connected with the voltage amplifying circuit and is grounded through the integrating capacitor.

In one embodiment, the voltage amplifying circuit comprises a first triode, a second resistor and a third resistor;

the base electrode of the first triode is connected with the integrating circuit, the collector electrode of the first triode is connected with the current amplifying circuit, and the emitter electrode of the first triode is grounded through the second resistor and is connected with the fan and the current amplifying circuit through the third resistor.

In one embodiment, the current amplifying circuit comprises a second triode and a fourth resistor;

the base electrode of the second triode is connected with the collector electrode of the first triode and is connected with the power supply through the fourth resistor, the collector electrode of the second triode is connected with the third resistor and the common end of the fan, and the emitting electrode of the second triode is connected with the power supply.

In a second aspect, a heat dissipation apparatus is provided, which includes a main controller, a fan, and the fan speed control circuit according to any of the above embodiments, wherein the fan speed control circuit is connected to the main controller and the fan.

In a third aspect, an electronic device is provided, which comprises the heat dissipation device as described above.

The fan rotating speed control circuit receives the fan configuration rotating speed instruction of the main controller and the feedback rotating speed of the fan through the driving circuit, outputs the driving voltage to the amplifying circuit according to the fan configuration rotating speed instruction and the feedback rotating speed of the fan, outputs the amplified driving signal to the fan through the amplifying circuit, controls the rotating speed of the fan, can adjust the rotating speed of the fan according to actual needs, and improves the heat dissipation effect.

Drawings

FIG. 1 is a block diagram of a fan speed control circuit according to an embodiment;

FIG. 2 is a diagram illustrating a structure of a control chip for controlling the rotational speeds of three fans in an embodiment;

FIG. 3 is a block diagram of an embodiment of an amplifier circuit;

fig. 4 is a schematic diagram of an embodiment of an amplifier circuit.

Description of reference numerals: 100-driving circuit, 200-amplifying circuit, 201-integrating circuit, 202-voltage amplifying circuit and 203-current amplifying circuit.

Detailed Description

To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, the integrating resistance may be referred to as a second resistance, and similarly, the second resistance may be referred to as an integrating resistance, without departing from the scope of the present application. The integrating resistance and the second resistance are both resistances, but they are not the same resistance.

It is to be understood that "connection" in the following embodiments is to be understood as "electrical connection", "communication connection", and the like if the connected circuits, modules, units, and the like have communication of electrical signals or data with each other.

As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

In one embodiment, referring to fig. 1, a fan rotation speed control circuit is provided, which includes a driving circuit 100 and an amplifying circuit 200. The driving circuit 100 is connected to the main controller and the fan, and the amplifying circuit 200 is connected to the driving circuit 100 and the fan. The driving circuit 100 is configured to receive a fan configuration rotation speed instruction of the main controller and a feedback rotation speed of the fan, and output a driving voltage; the amplifying circuit 200 is configured to receive and amplify the driving voltage, and output the amplified driving signal to the fan.

The fan configuration rotating speed instruction of the main controller is determined by the main controller according to the current operation state of the electronic product and the heating condition of the device in the area where the fan is located. It can be understood that when the device generates heat seriously, the rotating speed of the fan needs to be increased to increase the effect of convection cooling, and the service life of the device is prolonged; otherwise, the rotation speed of the fan can be reduced to save energy. The configuration rotational speed command may be a rotational speed or a signal corresponding to the rotational speed, and in short, the specific content of the configuration rotational speed command is not limited in this embodiment.

The feedback rotating speed of the fan is calculated by the feedback signal of the fan. The feedback signal of the fan is a signal corresponding to the rotating speed of the fan and sent by the internal device of the fan. The feedback signal of the fan can be a pulse signal generated based on Hall effect: the magnetic element is installed at the rotating part of the fan, and in the rotating process of the fan, the magnetic element forms a Hall sensing switch, generates a pulse signal, and sends the pulse signal to the driving circuit after shaping and protection. Besides, the actual rotating speed of the fan can be measured based on the photoelectric effect. In short, the embodiment does not limit the manner of obtaining the feedback rotation speed of the fan.

Specifically, after receiving the fan configuration rotation speed command of the main controller and the feedback rotation speed of the fan, the driving circuit 100 configures the driving voltage of the fan according to the configuration rotation speed and the actual rotation speed of the fan, and outputs the driving voltage to the amplifying circuit 100. The amplifying circuit 200 receives the driving voltage, amplifies the driving voltage, and outputs the amplified driving signal to the fan. Thus, the rotational speed control of the primary fan is completed. For the same fan, the rotation speed is proportional to the driving voltage. It is understood that in the present embodiment, the voltage range applied to the fan is not unique, and different driving circuits 100 and amplifying circuits 200 can be designed to match the requirements of different fans according to the parameters of the actual fan. Optionally, the driving voltage output by the driving circuit 100 is 2.2V to 3.6V, and the driving voltage applied to the fan after being amplified by the amplifying circuit 200 is 5V to 12V. Furthermore, the driving circuits and the amplifying circuits which correspond to the fans can be arranged, and the rotation speed control of the fans can be realized at the same time.

In one embodiment, the driving circuit is an IIC control circuit.

The IIC control circuit is a control circuit based on a serial communication bus structure and supports a multi-master-slave architecture. By using the IIC control circuit, each device can be directly connected by a lead, the control of a plurality of devices is completed simultaneously, the number of connecting wires is small, and the structure is simple. Specifically, the integrated control mode may be implemented by the IIC Slave.

Further, the feedback rotating speed of the fan, that is, the current actual rotating speed of the fan, can be calculated according to the feedback signal of the fan. As described above, the feedback signal of the fan is not unique, and therefore, the calculation process of the fan feedback rotation speed is also not unique, and the present embodiment does not limit the calculation method of the fan feedback rotation speed. After the IIC control circuit completes the comparison between the fan configuration rotation speed and the fan feedback rotation speed, it outputs the driving voltage to the amplifying circuit 200 according to the comparison result. When the configured rotating speed of the fan is greater than the feedback rotating speed of the fan, the IIC control circuit reduces the driving voltage and outputs the reduced driving voltage to the amplifying circuit 200; when the configured rotating speed of the fan is less than the feedback rotating speed of the fan, the IIC control circuit increases the driving voltage and outputs the increased driving voltage to the amplifying circuit 200; when the configured rotation speed of the fan is equal to the feedback rotation speed of the fan, the IIC control circuit keeps the driving voltage unchanged and outputs the driving voltage to the amplifying circuit 200. Optionally, a threshold may be preset, when the difference between the feedback rotation speed and the configured rotation speed is within a preset threshold range, the driving voltage is kept unchanged, otherwise, the driving voltage is adjusted according to the feedback rotation speed and the configured rotation speed, and the rotation speed of the fan is adjusted.

In the above embodiment, the IIC control circuit is used to compare the feedback rotation speed of the fan with the configured rotation speed, and output the driving voltage according to the comparison result, so that the circuit structure can be simplified, the system resources can be reduced, and the cost can be reduced. In one embodiment, the IIC control circuit includes a control chip. The control chip is connected to the main controller, the fan and the amplifying circuit 200. After receiving a fan configuration rotating speed instruction sent by the main controller, the control chip calculates the feedback rotating speed of the fan according to a feedback signal of the fan, compares the feedback rotating speed of the fan with the configuration rotating speed, and outputs a driving voltage to the amplifying circuit 200 according to a comparison result.

Further, the fan configuration rotation speed command of the main controller may include configuration rotation speeds of a plurality of fans, and the feedback rotation speed of a fan refers to the feedback rotation speed of a certain fan. Therefore, a plurality of signal input channels for receiving the feedback rotating speed of the fan can be arranged, and correspondingly, a plurality of signal output channels corresponding to the number of the signal input channels can be arranged for outputting corresponding driving signals to different fans. Thus, the rotation speed of the plurality of fans can be controlled.

In the above embodiment, the control chip is arranged, the feedback rotation speed of the fan is calculated according to the feedback signal of the fan, the feedback rotation speed of the fan is compared with the configuration rotation speed sent by the main controller, and the driving voltage is output to the amplifying circuit 200 according to the comparison result, so that the operation speed of the fan rotation speed control circuit can be increased.

In one embodiment, the number of the fans is more than two, and the number of the amplifying circuits is the same as that of the fans. The feedback input end of the control chip is connected with the corresponding fan, and the drive output end of the control chip is connected with the corresponding fan through each amplifying circuit.

Referring to fig. 2, a schematic diagram of a control chip capable of controlling the rotation speeds of three fans is provided. The signal input end ERROUT of the control chip is connected with the main controller and used for receiving a fan configuration rotating speed instruction of the main controller. The fan configuration rotating speed instruction of the main controller can comprise configuration rotating speeds of a plurality of fans, the configuration rotating speeds of different fans can be the same or different, and the main controller determines the fan configuration rotating speed instruction according to the current operation state of the electronic product and the heating condition of devices in the area where the fans are located. The first feedback input end FP1 of the control chip is used for receiving the feedback rotating speed of the first fan, the corresponding second feedback input end FP2 is used for receiving the feedback rotating speed of the second fan, and the third feedback input end FP3 is used for receiving the feedback rotating speed of the third fan. The first driving output end FCOUT1 of the control chip is used for outputting a driving voltage to the first fan, the corresponding second driving output end FCOUT2 is used for outputting a driving voltage to the second fan, and the third driving output end FCOUT3 is used for outputting a driving voltage to the third fan. In addition, the power supply terminal VCC of the control chip is used for connecting a power supply, and the ground terminal GND is used for grounding. Further, more than three feedback input ends and more than three driving output ends can be designed according to actual needs to control the rotating speed of more than three fans, and the number of the specifically controlled fans is not limited in the embodiment.

Specifically, the IIC Slave needs to be initialized before the fan rotation speed control. When the control chip receives a fan configuration rotating speed instruction of the main controller, the configuration rotating speed of the fan is compared with the feedback rotating speed, the driving voltage of the fan is adjusted according to the comparison result, the adjusted driving voltage is output to the amplifying circuit through the driving output end, and the driving signal is output to the corresponding fan after the amplifying circuit amplifies the driving voltage. When the configuration rotating speed of the fan is greater than the feedback rotating speed of the fan, the driving voltage is reduced; when the configured rotating speed of the fan is less than the feedback rotating speed of the fan, the driving voltage is increased; when the configured speed of the fan is equal to the feedback speed of the fan, the driving voltage will be kept constant. Further, a threshold value can be preset, when the difference value between the feedback rotating speed and the configuration rotating speed is within the range of the preset threshold value, the driving voltage is kept unchanged, otherwise, the driving voltage is adjusted according to the feedback rotating speed and the configuration rotating speed, and the rotating speed of the fan is adjusted.

In the above embodiment, the control chip is used, and the plurality of feedback input ends and the plurality of drive output ends are arranged on the control chip, so that the rotation speed control of the plurality of fans can be realized simultaneously, the circuit is simple and reliable, the system resources can be reduced, the cost is reduced, and the operation speed is increased.

In one embodiment, referring to fig. 3, the amplifying circuit 200 includes an integrating circuit 201, a voltage amplifying circuit 202 and a current amplifying circuit 203. The integrating circuit 201 is connected with the driving circuit 100 and the voltage amplifying circuit 202, and the voltage amplifying circuit 202 is connected with the current amplifying circuit 203 and the fan; the current amplification circuit 203 is also connected to a power supply.

The integration circuit is a circuit that makes the output voltage proportional to the time integral value of the input voltage. An integration circuit is used before power amplification, so that a tiny deviation signal can be accumulated, and errors can be eliminated. The voltage amplifying circuit is used for obtaining an output voltage signal stronger than the input voltage signal. . For weak voltage signals, multi-stage voltage amplification is commonly used, and the cascade mode comprises direct coupling, resistance-capacitance coupling, transformer coupling and the like, and the requirements are high amplification factor, flat frequency response and small distortion. The current amplifying circuit is used for obtaining an output current signal stronger than the input current signal. Generally, the waveforms of the output signals of the voltage amplifying circuit and the current amplifying circuit are consistent with the frequency of the input signals, but have larger amplitudes.

Specifically, after receiving the driving voltage signal sent by the driving circuit 100, the amplifying circuit 200 firstly performs integration processing on the signal through the integrating circuit 201 to eliminate an error, and then performs power amplification through the voltage amplifying circuit 202 and the current amplifying circuit 203 to obtain an electric signal required by fan rotation speed control, and sends the driving signal to the fan to complete the fan rotation speed control. As described above, since the parameters of the fans are not unique, the driving voltages required by the corresponding fans are also not unique, but the ranges of the driving voltages output by the same driving circuit are fixed. At the moment, power amplification can be carried out by designing different voltage amplification circuits and current amplification circuits, the range of the driving signals output to the fan is changed, and the rotating speed control of the fan with different parameters is realized.

In the above embodiment, the error can be eliminated by setting the integrating circuit, and the received driving voltage can be amplified by setting the voltage amplifying circuit and the current amplifying circuit, so as to meet the use requirements of different fans, reduce the limitation on the parameters of the driving circuit, and improve the flexibility of the fan rotating speed control circuit.

In one embodiment, referring to fig. 4, the integrating circuit 201 includes an integrating resistor R1 and an integrating capacitor C1. One end of the integrating resistor R1 is connected to the driving circuit 100, and the other end is connected to the voltage amplifying circuit 202; and to ground through integrating capacitor C1.

Specifically, the driving voltage signal output from the driving circuit 100 has a certain value and can be approximated to a square wave signal. When receiving the driving voltage signal, the integrating circuit 201 divides the voltage by the integrating resistor R1, and then starts charging the integrating capacitor C1. After the integrating capacitor C1 has charged to the maximum voltage, it begins to discharge slowly through the integrating resistor R1. Therefore, the square wave signal input into the integrating circuit 201 is converted into a sawtooth wave signal after passing through the integrating resistor R1 and the integrating capacitor C1, so that the direct current and slowly varying components of the input signal are highlighted, the variation of the input signal is reduced, and the error is eliminated.

In the above embodiment, by using the RC integrating circuit, the integrating operation can be performed on the input driving signal, so as to reduce the interference, facilitate the elimination of the error, and improve the accuracy of the fan rotation speed control.

In one embodiment, with continued reference to fig. 4, the voltage amplifying circuit 202 includes a first transistor Q1, a second resistor R2, and a third resistor R3. The base of the first triode Q1 is connected with the integrating circuit 201, the collector of the first triode Q1 is connected with the current amplifying circuit 203, and the emitter of the first triode Q1 is grounded through the second resistor R2 and connected with the fan and the current amplifying circuit 203 through the third resistor R3.

Specifically, the voltage signal input from the integrating circuit 201 is output to the fan by the amplifying action of the first triode Q1 in the voltage amplifying circuit 202, and the fan adjusts the rotation speed according to the received driving signal.

In the above embodiment, through setting up first triode Q1, second resistance R2 and third resistance R3, enlarge drive voltage, can carry out the model selection of first triode Q1, second resistance R2 and third resistance R3 according to actual need, satisfy the drive requirement of different parameter fans, can improve the flexibility that improves fan rotational speed control circuit, still be favorable to improving fan rotational speed control circuit's output, improve energy utilization.

In one embodiment, with continued reference to fig. 4, the current amplifying circuit 203 includes a second transistor Q2 and a fourth resistor R4. The base electrode of the second triode Q2 is connected with the collector electrode of the first triode Q1 and is connected with the power supply through the fourth resistor R4, the collector electrode of the second triode Q2 is connected with the common end of the third resistor R3 and the fan, and the emitter electrode of the second triode Q2 is connected with the power supply.

Specifically, the current signal output by the power supply is amplified by the second transistor Q2 in the current amplifying circuit 203, and then output to the fan together with the amplified voltage signal output by the voltage amplifying circuit 202. And then the fan adjusts the rotating speed according to the received driving signal.

In the above embodiment, the second triode Q2 is arranged to amplify the driving current, so as to meet the driving requirements of fans with different parameters, improve the flexibility of the fan speed control circuit, improve the output power of the fan speed control circuit, and improve the energy utilization rate.

In one embodiment, a heat dissipation apparatus is provided, which includes a main controller, a fan, and the fan speed control circuit of any of the above embodiments, wherein the fan speed control circuit is connected to the main controller and the fan.

Wherein, the fan includes structures such as motor, control panel, flabellum. The control board controls the motor to drive the fan blades to rotate according to the received driving signal, and sends the feedback rotating speed of the fan to the fan rotating speed control circuit. Furthermore, the fan comprises an air draft fan and a blast fan, wherein the air draft fan is suitable for electronic equipment with small wind resistance and uniform heat source distribution; the blower fan is suitable for electronic equipment with large wind resistance and concentrated heat sources. When necessary, the fans can be connected in series, in parallel or in series-parallel to improve the wind pressure and the wind volume and improve the heat dissipation effect.

Specifically, the main controller sends a fan configuration rotating speed instruction to the fan rotating speed control circuit according to the current operation state of the electronic product and the heating condition of the device in the area where the fan is located. The fan rotating speed control circuit outputs a driving signal to the corresponding fan according to the configured rotating speed and the feedback rotating speed of the fan, and the fan performs rotating speed control according to the driving signal to improve the heat dissipation effect.

According to the heat dissipation device, the fan configuration rotating speed instruction of the main controller and the feedback rotating speed of the fan are received through the fan rotating speed control circuit, the driving signal is output to the corresponding fan according to the fan configuration rotating speed instruction and the feedback rotating speed of the fan, the rotating speed of the fan is controlled, the rotating speed of the fan can be adjusted according to actual needs, and the heat dissipation effect is improved.

In one embodiment, an electronic device is provided, comprising the heat dissipation device of any of the above embodiments.

Specifically, the electronic device is a device that is composed of electronic components such as an integrated circuit, a transistor, and an electron tube, and that implements a certain function by applying an electronic technology. Electronic devices include projectors, printers, facsimile machines, electronic computers, and robots controlled by electronic computers, numerical control or program control systems, and the like. The heat dissipation device is arranged in the electronic device to perform heat dissipation treatment on the electronic device, so that the electronic device and components thereof can be ensured to normally work within a specified temperature range, the service life of the electronic device is prolonged,

the technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the utility model. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A fan speed control circuit, comprising:

the driving circuit comprises a control chip, the control chip is provided with a driving output end for outputting the driving voltage, a signal input end for receiving the fan configuration rotating speed instruction and a feedback input end for receiving the feedback rotating speed of the fan, and the control chip is configured to compare the fan configuration rotating speed with the fan feedback rotating speed and adjust the driving voltage according to the comparison result;

2. The fan speed control circuit of claim 1 wherein the driver circuit is an IIC control circuit.

3. The fan speed control circuit of claim 2 wherein the IIC control circuit comprises a control chip, the control chip being connected to the main controller, the fan, and the amplification circuit.

4. The fan speed control circuit according to claim 3, wherein the number of the fans is two or more, and the number of the amplifying circuits is the same as the number of the fans; the feedback input end of the control chip is connected with the corresponding fan, and the driving output end of the control chip is connected with the corresponding fan through each amplifying circuit.

5. The fan speed control circuit of claim 1 wherein the amplification circuit comprises an integration circuit, a voltage amplification circuit, and a current amplification circuit; the integrating circuit is connected with the driving circuit and the voltage amplifying circuit; the voltage amplifying circuit is connected with the current amplifying circuit and the fan; the current amplifying circuit is connected with a power supply.

6. The fan speed control circuit of claim 5 wherein the integrating circuit comprises an integrating resistor and an integrating capacitor;

7. The fan speed control circuit of claim 5 wherein the voltage amplification circuit comprises a first transistor, a second resistor, and a third resistor;

8. The fan speed control circuit of claim 7 wherein the current amplification circuit comprises a second transistor and a fourth resistor;

9. A heat sink apparatus comprising a main controller, a fan, and the fan speed control circuit according to any one of claims 1 to 8, wherein the fan speed control circuit connects the main controller and the fan.

10. An electronic device comprising the heat dissipating device of claim 9.