Fan control circuit and computer mainboard with same

Abstract

The utility model provides a fan control circuit and a computer mainboard with the fan control circuit. The fan control circuit comprises a fan connector used for being connected with a fan, a control unit and a first protection circuit. The control unit comprises a first pin. A power pin of the fan connector is connected to a first power supply, and a grounding pin is grounded. The first protection circuit is connected between a rotating speed control pin of the fan connector and a first pin and comprises a first resistor, a second resistor, a third resistor and a diode. The first end of the first resistor is connected with the first pin, and the second end of the first resistor is connected with the rotating speed control pin. The second resistor is connected between the first end of the first resistor and the ground. The third resistor is connected between the second end of the first resistor and the second power supply. The anode of the diode is connected to the rotating speed control pin, and the cathode is connected to the second power supply. According to the utility model, the control unit can be protected when the fan is hot-plugged, the circuit structure is simple, and the cost is saved.

Description

Technical Field

[0001] The utility model relates to the technical field of electronics, in particular to a fan control circuit and a computer mainboard with the fan control circuit. Background Art

[0002] The operating temperature of electronic devices, such as computers, directly determines their service life and operational stability. Furthermore, electronic devices generate a significant amount of heat during operation. Therefore, maintaining the operating temperature of each component within a reasonable range requires not only ensuring the operating environment temperature is within a reasonable range, but also timely heat dissipation. Heat dissipation technology is used to transfer the heat generated within the device to the external environment, ensuring the internal temperature of the device remains within a safe range.

[0003] Electronic equipment heat dissipation methods primarily include natural cooling and forced cooling. Natural cooling utilizes the device's natural convection and radiation to dissipate heat, while forced cooling requires auxiliary means to transfer heat from the heat-generating component to the surrounding environment. These methods, such as air cooling, water cooling, and liquid cooling, are more suitable for high-power devices like computers. While liquid cooling and water cooling already exist for computer motherboards, and other cooling methods may emerge in the future, air cooling currently offers the most cost-effective cooling options.

[0004] Air cooling inevitably requires the use of a cooling fan. When a computer motherboard or the cooling fan on it malfunctions and requires repair, the fan often needs to be removed from the motherboard. Users and repairers often remove the fan directly by hot-swapping it. However, when hot-swapping a fan, the voltage on the fan pins drops rapidly, generating a large current pulse. This current, when transferred to the fan's control chip, could potentially damage it. Therefore, hot-swapping protection is necessary for cooling fans.

[0005] Currently, hot-swap protection is generally achieved by adding ESD (Electro-Staticdischarge) or TVS (Transient Voltage Suppressor) protection to prevent static electricity. However, ESD and TVS are relatively expensive, which will increase costs. Summary of the Invention

[0006] The purpose of the utility model is to provide a fan control circuit and a computer motherboard with the fan control circuit, which can protect the control unit when the fan is hot-plugged, and has a simple circuit structure and saves costs.

[0007] To achieve the above-mentioned purpose, the utility model provides a fan control circuit, comprising a fan connector for connecting a fan, a control unit and a first protection circuit, wherein the control unit includes a first pin; the fan connector includes a power pin, a speed control pin and a ground pin, the power pin is connected to a first power supply, and the ground pin is grounded; the first protection circuit is connected between the speed control pin and the first pin, and the first protection circuit includes a first resistor, a second resistor, a third resistor and a diode, the first end of the first resistor is connected to the first pin of the control unit, the second end of the first resistor is connected to the speed control pin, the second resistor is connected between the first end of the first resistor and ground, the third resistor is connected between the second end of the first resistor and a second power supply, the anode of the diode is connected to the speed control pin, and the cathode of the diode is connected to the second power supply; when the first pin of the control unit outputs a high-level signal, the voltage across the second resistor is consistent with the operating voltage of the control unit.

[0008] Preferably, the first protection circuit further includes a first capacitor, one end of the first capacitor is connected to the first pin of the control unit, and the other end is grounded.

[0009] Preferably, the fan connector also includes a speed feedback pin, the control unit also includes a second pin, the fan control circuit also includes a second protection circuit, the second protection circuit includes a switch unit, the switch unit includes a control end and an output end, the control end of the switch unit is connected to the speed feedback pin, the output end is connected to the second pin of the control unit, and the second pin is also connected to a third power supply via a fourth resistor, wherein when the speed feedback pin outputs a first level signal to the control end of the switch unit, the switch unit is turned on and outputs a low level signal to the second pin via its output end, and when the speed feedback pin outputs a second level signal to the control end of the switch unit, the switch unit is turned off.

[0010] Preferably, the speed feedback pin is further connected to the first power supply via a fifth resistor.

[0011] Preferably, the output voltage of the third power supply is 3.3V, and the control unit is an embedded controller.

[0012] Preferably, the switching unit includes an NMOS tube, the gate of the NMOS tube is the control end of the switching unit, connected to the speed feedback pin; the drain of the NMOS tube is the output end of the switching unit, connected to the second pin of the control unit, and connected to the third power supply via the fourth resistor; the source of the NMOS tube is grounded; the first level signal is a high level signal, and the second level signal is a low level signal.

[0013] Preferably, the fan control circuit further includes a second capacitor and a third capacitor, and the second capacitor and the third capacitor are connected in parallel between the first power supply and ground.

[0014] Preferably, the output voltage of the first power supply is 12V, and the output voltage of the second power supply is 12V.

[0015] Preferably, the control unit is an embedded controller.

[0016] The utility model also provides a computer mainboard, comprising the above-mentioned fan control circuit.

[0017] The beneficial effects of the present invention are as follows: the fan control circuit and the computer motherboard having the fan control circuit of the present invention, by providing a first protection circuit composed of a resistor and a diode between the first pin of the control unit and the speed control pin of the fan connector, can protect the control unit from being damaged by the influence of the large voltage and current generated on the speed control pin when the fan is hot-plugged, and can also effectively protect the fan when the PWM of the fan is too high, and the circuit structure of the first protection circuit is simple, and no components such as ESD and TVS are required, which is more cost-effective; moreover, the fan control circuit and the computer motherboard having the fan control circuit of the present invention, by providing a second protection circuit between the second pin of the control unit and the speed feedback pin of the fan connector, can protect the control unit from being damaged by the influence of the large voltage and current generated on the speed feedback pin when the fan is hot-plugged, and the circuit structure of the second protection circuit is simple, and no components such as ESD and TVS are required, which is more cost-effective; thus, it can be seen that the present invention can protect the control unit of the fan when the fan is hot-plugged, so that the control unit is not affected by the hot-plugging of the fan, and can also effectively protect the fan when the PWM of the fan is too high, and the circuit structure is simple, which is cost-effective. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings are only provided for reference and explanation and are not intended to limit the present invention.

[0019] Figure 1This is a circuit wiring diagram of the fan control circuit of the present invention. DETAILED DESCRIPTION

[0020] In order to further illustrate the technical means and effects adopted by the present invention, the following is a detailed description of the preferred embodiments of the present invention and the accompanying drawings.

[0021] The utility model provides a fan control circuit and a computer mainboard with the fan control circuit, which can realize hot plug protection of the fan and prevent the hot plug of the fan from damaging the control unit, and has a simple circuit structure and saves costs.

[0022] like Figure 1 As shown, the fan control circuit of the present invention includes a fan connector FAN1 for connecting a fan, a control unit U1 and a first protection circuit 10 .

[0023] The control unit U1 includes a first pin P1 for outputting a PWM (Pulse Width Modulation) signal. The fan connector FAN1 includes a power pin VCC, a speed control pin PWM, and a ground pin GND. The power pin VCC is connected to the first power supply PS1, and the ground pin GND is connected to ground. The first protection circuit 10 is connected between the speed control pin PWM and the first pin P1 and includes a first resistor R1, a second resistor R2, a third resistor R3, and a diode D1. The first end of the first resistor R1 is connected to the first pin P1 of the control unit U1, and the second end of the first resistor R1 is connected to the speed control pin PWM. The second resistor R2 is connected between the first end of the first resistor R1 and ground. The third resistor R3 is connected between the second end of the first resistor R1 and the second power supply PS2. The anode of the diode D1 is connected to the speed control pin PWM, and the cathode of the diode D1 is connected to the second power supply PS2. When the first pin P1 of the control unit U1 outputs a high-level signal, the voltage across the second resistor R2 is consistent with the operating voltage of the control unit U1.

[0024] Specifically, the fan control circuit of the present invention includes a first protection circuit 10 between the first pin P1 of the control unit U1 and the speed control pin PWM of the fan connector FAN1. The first pin P1 of the control unit U1 is configured to output a PWM signal to the fan connector FAN1. The first protection circuit 10 includes a first resistor R1, a second resistor R2, and a third resistor R3. When the first pin P1 of the control unit U1 outputs a high-level signal, the first resistor R1, the second resistor R2, the third resistor R3, and the second power supply PS2 form a voltage divider circuit. The voltage divided by the second resistor R2 is consistent with the operating voltage of the control unit U1, thereby stabilizing the voltage of the first pin P1 of the control unit U1 at the operating voltage.

[0025] The voltage across the second resistor R2 must be consistent with the operating voltage of the control unit U1. This can be achieved by adjusting the resistance values of the first resistor R1, the second resistor R2, and the third resistor R3 according to the operating voltage of the control unit U1. For example, using the embedded chip model IT8528, the voltage across the second resistor R2 should be approximately 3.3V.

[0026] At the same time, the resistors R1, R2, and R3 also play a role in current limiting.

[0027] When the first pin P1 of the control unit U1 outputs a low-level signal, the speed control pin PWM also receives a low-level signal.

[0028] With such a configuration, the first protection circuit 10 of the present invention can protect the fan by limiting the current of the resistor when the fan's PWM is too high. Compared with the use of MOS tubes, since the PWM frequencies of different fan models are different and the switching frequency of the MOS tube has a certain upper limit, when the fan's PWM is too high, the MOS tube will cause signal distortion or frequency reduction due to insufficient switching. The first protection circuit 10 of the present invention avoids this problem and can effectively protect the fan when the fan's PWM is too high.

[0029] Furthermore, the first protection circuit 10 also includes a diode D1 connected to the second power supply PS2. When hot-plugging the fan on the fan connector FAN1, the high voltage and high current generated by the speed control pin PWM of the fan connector FAN1 is first conducted through the diode D1 to the power copper foil of the second power supply PS2 (once the pulse voltage generated by the speed control pin PWM exceeds the output voltage of the second power supply PS2). Then, when passing through the first resistor R1, the current is limited to a very small amplitude due to the current limiting effect of the first resistor R1, thereby protecting the control unit U1 from damage due to the high current on the speed control pin PWM.

[0030] It can be seen that the first protection circuit 10 of the fan control circuit of the present invention can realize the connection between the first pin P1 of the control unit U1 and the speed control pin PWM of the fan connector FAN1, ensuring the normal and stable operation of the two, and can also realize the protection of the control unit U1 when the fan is hot-plugged, and the circuit structure is simple, saving costs.

[0031] It can be seen from this that the first resistor R1 can be selected to have a larger resistance.

[0032] Furthermore, the first protection circuit 10 further includes a first capacitor C1, one end of which is connected to the first pin P1 of the control unit U1, and the other end is grounded. The first capacitor C1 can play a role in filtering and reducing interference.

[0033] Furthermore, the fan connector FAN1 also includes a speed feedback pin TACH for outputting speed information of the fan connected to the fan connector FAN1. The control unit U1 also includes a second pin P2. The fan control circuit also includes a second protection circuit 20, which is disposed between the speed feedback pin TACH of the fan connector FAN1 and the second pin P2 of the control unit U1. The second protection circuit 20 includes a switch unit 21, which includes a control end and an output end. The control end of the switch unit 21 is connected to the speed feedback pin TACH, and the output end is connected to the second pin P2 of the control unit U1. The second pin P2 is also connected to a third power supply PS3 via a fourth resistor R4. When the speed feedback pin TACH outputs a first-level signal to the control end of the switch unit 21, the switch unit 21 turns on and outputs a low-level signal to the second pin P2 via its output end. When the speed feedback pin TACH outputs a second-level signal to the control end of the switch unit 21, the switch unit 21 turns off. When the switch unit 21 is turned off, the second pin P2 receives a high level signal due to the fourth resistor R4 and the third power source PS3.

[0034] In this way, the speed feedback pin TACH of the fan connector FAN1 is isolated from the control unit U1 by the switch unit 21, which can prevent the high voltage generated on the speed feedback pin TACH of the fan connector FAN1 from being loaded onto the control unit U1 when the fan on the fan connector FAN1 is hot plugged.

[0035] Furthermore, the speed feedback pin TACH is connected to the first power supply PS1 via a fifth resistor R5. This configuration allows the high current generated by the speed feedback pin TACH of the fan connector FAN1 during hot-plugging of a fan on the fan connector FAN1 to flow into the power copper foil of the first power supply PS1 via the fifth resistor R5.

[0036] Preferably, in one embodiment, the switch unit 21 includes an NMOS transistor Q1. The gate of the NMOS transistor Q1 serves as the control terminal of the switch unit 21 and is connected to the speed feedback pin TACH. The drain of the NMOS transistor Q1 serves as the output terminal of the switch unit 21 and is connected to the second pin P2 of the control unit U1 and to the third power supply PS3 via the fourth resistor R4. The source of the NMOS transistor Q1 is grounded. The first level signal is a high level signal, and the second level signal is a low level signal.

[0037] When the speed feedback pin TACH outputs a first level signal, the NMOS tube Q1 is turned on, that is, the switch unit 21 is turned on, and the drain of the NMOS tube Q1 outputs a low level signal to the second pin P2 of the control unit U1; when the speed feedback pin TACH outputs a second level signal, the NMOS tube Q1 is turned off, that is, the switch unit 21 is closed, and the second pin P2 receives a high level signal.

[0038] Since the withstand voltage of the NMOS tube Q1 can reach 50V, it can effectively prevent the high voltage generated by the speed feedback pin TACH when the fan is hot-plugged, and form isolation between the fan connector FAN1 and the control unit U1; when the fan is hot-plugged, the pulse current generated by the speed feedback pin TACH then flows into the power copper foil of the first power supply PS1 through the fifth resistor R5.

[0039] Of course, the structure of the switch unit 21 is not limited thereto, and other switch structures that can achieve the same function may also be used.

[0040] It can be seen that the second protection circuit 20 of the fan control circuit of the present invention can realize the connection between the second pin P2 of the control unit U1 and the speed feedback pin TACH of the fan connector FAN1, ensuring the normal and stable operation of the two, and can also realize the protection of the control unit U1 when the fan is hot-plugged, and the circuit structure is simple, saving costs.

[0041] Furthermore, the fan control circuit may further include a second capacitor C2 and a third capacitor C3, wherein the second capacitor C2 and the third capacitor C3 are connected in parallel between the first power supply PS1 and the ground.

[0042] In a preferred embodiment, the control unit U1 is an embedded controller.

[0043] Next, the working principle of the fan control circuit of the present invention will be described with reference to a specific embodiment of the fan control circuit of the present invention.

[0044] Still see Figure 1 The circuit wiring diagram of the fan control circuit shown in FIG. 1 shows that when the fan control circuit is set on a computer motherboard, that is, when the fan control circuit is a fan control circuit on the computer motherboard, the first power supply PS1 and the second power supply PS2 are the P12V power supplies of the computer motherboard, and the output voltages are both 12V.

[0045] The control unit U1 can adopt an embedded controller, whose operating voltage is 3.3V (but not limited to this), then the third power supply PS3 can be the P3V3 power supply of the computer motherboard, and the output voltage is 3.3V; the voltage obtained by the second resistor R2 when the first pin P1 of the control unit U1 outputs a high-level signal is approximately 3.3V. As shown in the figure, the resistance values of the first resistor R1, the second resistor R2, and the third resistor R3 can be 10K ohms, 5.6K ohms, and 4.7K ohms, respectively. Among them, the resistance value of the first resistor R1 is relatively large, which can play a good current limiting role.

[0046] When the fan provided at the fan connector FAN1 is operating normally, in the first protection circuit 10, when the first pin P1 of the control unit U1 outputs a high-level signal, the voltage on the second resistor R2 is 3.3V, so that the voltage of the first pin P1 of the control unit U1 is stabilized at 3.3V; when the first pin P1 of the control unit U1 outputs a low-level signal, the speed control pin PWM also receives a low-level signal. In the second protection circuit 20, when the speed feedback pin TACH outputs a first-level signal, the NMOS transistor Q1 is turned on, that is, the switch unit 21 is turned on, and the drain of the NMOS transistor Q1 outputs a low-level signal to the second pin P2 of the control unit U1; when the speed feedback pin TACH outputs a second-level signal, the NMOS transistor Q1 is turned off, that is, the switch unit 21 is turned off, and the second pin P2 receives a high-level signal.

[0047] Once a fan hot-swap occurs, in the first protection circuit 10, if the high voltage generated on the speed control pin PWM of the fan connector FAN1 exceeds 12V, it will first be conducted to the power copper foil of the second power supply PS2 through the diode D1. Then, when passing through the first resistor R1, the current will be limited to a very small amplitude under the current limiting effect of the first resistor R1, thereby protecting the control unit U1 from being damaged by the large current on the speed control pin PWM; in the second protection circuit 20, the high voltage generated on the speed feedback pin TACH of the fan connector FAN1 will not be loaded onto the control unit U1 due to the isolation effect of the NMOS tube Q1, and the corresponding pulse current can flow into the power copper foil of the first power supply PS1 through the fifth resistor R5, thereby protecting the control unit U1 from being damaged by the large current on the speed feedback pin TACH.

[0048] Here, since the first power supply PS1 and the second power supply PS2 are 12V power supplies, their power supply copper foils are larger and can withstand higher voltages. In addition, the P12V power supply on the computer motherboard itself is directly output by the ATX power supply, so it has high ESD protection and better tolerance.

[0049] Therefore, the fan control circuit of the present invention can implement hot-swap protection for the fan, thereby preventing the hot-swap of the fan from damaging the control unit.

[0050] The utility model also provides a computer mainboard, comprising the above-mentioned fan control circuit.

[0051] In one embodiment, the NMOS transistor Q1 can be a MOS transistor with a model number of L2N7002WT1G. In one embodiment, the control unit U1 can be an embedded controller, such as an embedded controller from the IT8528 series. In one embodiment, the fan connector FAN1 can be a connector for connecting a fan with a model number of SWF-251004C, but this is not limiting.

[0052] In summary, the fan control circuit of the present invention and the computer motherboard having the fan control circuit, by setting a first protection circuit composed of a resistor and a diode between the first pin of the control unit and the speed control pin of the fan connector, can protect the control unit from being damaged by the influence of the large voltage and current generated on the speed control pin when the fan is hot plugged, and can also effectively protect the fan when the PWM of the fan is too high, and the circuit structure of the first protection circuit is simple, without the need for components such as ESD and TVS, which is more cost-effective; and the fan control circuit of the present invention and the computer motherboard having the fan control circuit, by setting a second protection circuit between the second pin of the control unit and the speed feedback pin of the fan connector, can protect the control unit from being damaged by the influence of the large voltage and current generated on the speed feedback pin when the fan is hot plugged, and the circuit structure of the second protection circuit is simple, without the need for components such as ESD and TVS, which is more cost-effective. It can be seen from this that the utility model can protect the control unit of the fan when it is hot plugged, so that the control unit is not affected by the hot plugging of the fan, and can also effectively protect the fan when the PWM of the fan is too high, and the circuit structure is simple, which is cost-effective.

[0053] As described above, for ordinary technicians in this field, various other corresponding changes and modifications can be made according to the technical solution and technical concept of the utility model, and all these changes and modifications should fall within the scope of protection of the claims of the utility model.

Claims

1. A fan control circuit, characterized in that: It includes a fan connector for connecting a fan, a control unit and a first protection circuit, wherein the control unit includes a first pin; the fan connector includes a power pin, a speed control pin and a ground pin, the power pin is connected to a first power supply, and the ground pin is grounded; the first protection circuit is connected between the speed control pin and the first pin, and the first protection circuit includes a first resistor, a second resistor, a third resistor and a diode, the first end of the first resistor is connected to the first pin of the control unit, the second end of the first resistor is connected to the speed control pin, the second resistor is connected between the first end of the first resistor and the ground, the third resistor is connected between the second end of the first resistor and the second power supply, the anode of the diode is connected to the speed control pin, and the cathode of the diode is connected to the second power supply; when the first pin of the control unit outputs a high-level signal, the voltage across the second resistor is consistent with the operating voltage of the control unit.

2. The fan control circuit according to claim 1, wherein: The first protection circuit further includes a first capacitor, one end of the first capacitor is connected to the first pin of the control unit, and the other end is grounded.

3. The fan control circuit according to claim 1, wherein: The fan connector also includes a speed feedback pin, the control unit also includes a second pin, the fan control circuit also includes a second protection circuit, the second protection circuit includes a switch unit, the switch unit includes a control end and an output end, the control end of the switch unit is connected to the speed feedback pin, the output end is connected to the second pin of the control unit, and the second pin is also connected to a third power supply via a fourth resistor, wherein when the speed feedback pin outputs a first level signal to the control end of the switch unit, the switch unit is turned on and outputs a low level signal to the second pin via its output end, and when the speed feedback pin outputs a second level signal to the control end of the switch unit, the switch unit is turned off.

4. The fan control circuit according to claim 3, wherein: The speed feedback pin is also connected to the first power supply via a fifth resistor.

5. The fan control circuit according to claim 3, wherein: The output voltage of the third power supply is 3.3V, and the control unit is an embedded controller.

6. The fan control circuit according to claim 3, 4 or 5, characterized in that: The switching unit includes an NMOS tube, the gate of the NMOS tube is the control end of the switching unit, and is connected to the speed feedback pin; the drain of the NMOS tube is the output end of the switching unit, and is connected to the second pin of the control unit and is connected to the third power supply via the fourth resistor; the source of the NMOS tube is grounded; the first level signal is a high level signal, and the second level signal is a low level signal.

7. The fan control circuit according to claim 1, wherein: The fan control circuit further includes a second capacitor and a third capacitor, and the second capacitor and the third capacitor are connected in parallel between the first power supply and ground.

8. The fan control circuit according to claim 1, wherein: The output voltage of the first power supply is 12V, and the output voltage of the second power supply is 12V.

9. The fan control circuit according to claim 1, wherein: The control unit is an embedded controller.

10. A computer motherboard, characterized in that: The fan control circuit comprises the fan control circuit according to any one of claims 1 to 9.

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