Automatic temperature control and speed regulation circuit of direct-current fan

Abstract

The utility model relates to an automatic temperature control speed regulation circuit of a direct current fan, which comprises a first comparator, a first voltage division circuit, a third resistor, a first capacitor, a second comparator, a fourth resistor, a thermistor, a first MOS (Metal Oxide Semiconductor) tube, a diode, a second capacitor, a PWM (Pulse Width Modulation) output pin, a direct current anode output pin and a direct current cathode output pin, the input end of the PWM output pin is connected to the output end of the second comparator, the grid electrode of the first MOS tube is connected to the output end of the second comparator, one of the source electrode and the drain electrode is grounded, and the other one is connected to one end of the second capacitor, the positive electrode of the diode and the direct current negative electrode output pin. The other end of the second capacitor is connected with the cathode of the diode, the DC anode output pin and the anode of the first DC power supply. Compared with the prior art, the utility model has the advantages of wide application range, small volume and the like.

Description

Technical Field

[0001] The utility model relates to a fan control circuit, in particular to an automatic temperature control and speed regulation circuit for a DC fan. Background Art

[0002] DC speed regulation is currently widely used in fan control and typically consists of a triangle wave generation module, a comparator module, and a current amplifier module. For example, Chinese patent CN104265670A discloses a DC voltage feedback PWM temperature-controlled speed regulation circuit, which belongs to the field of DC fan control technology, particularly PWM temperature-controlled speed regulation technology for DC fans. The circuit comprises a temperature detection amplifier circuit consisting of an op amp, an op amp bias circuit, a temperature detection circuit, and a capacitor. The output of the temperature detection amplifier circuit is connected to a voltage comparator, the other input of which receives a triangle wave voltage generated by a triangle wave generator. The voltage comparator outputs a PWM signal to a power boost circuit, the output of which is connected to the DC fan.

[0003] However, DC speed control circuits, including the aforementioned DC voltage feedback PWM temperature control speed control circuit, generally have at least one of the following disadvantages:

[0004] 1) It needs to be matched one by one with the DC fan. The DC speed regulation of different DC fans cannot be used together, and the versatility is poor.

[0005] 2) For DC fans without PWM speed control lines, the failure rate is high or the size is large, and the requirements of small size and durability are met at the same time.

[0006] 3) It is impossible to take into account both fans with PWM speed control lines and fans without PWM speed control lines. Utility Model Content

[0007] The purpose of the utility model is to provide an automatic temperature control and speed regulation circuit for a DC fan.

[0008] The purpose of the utility model can be achieved through the following technical solutions:

[0009] A DC fan automatic temperature control and speed regulation circuit, comprising:

[0010] A first comparator, a first voltage divider circuit, a third resistor and a first capacitor, wherein the inverting input terminal of the first comparator is connected to the host computer through the third resistor, the non-inverting input terminal is connected to the voltage divider output terminal of the first voltage divider circuit, one end of the first voltage divider circuit is connected to the positive electrode of the first DC power supply, and the other end is grounded, one end of the first capacitor is connected to the inverting input terminal of the first comparator, and the other end is connected to the output terminal of the first comparator;

[0011] a second comparator, a fourth resistor, and a thermistor, wherein the fourth resistor and the thermistor are connected in series to form a second voltage divider circuit, one input end of the second comparator is connected to the output end of the first comparator, the other input end of the second comparator is connected to the voltage divider output end of the second voltage divider resistor, one end of the second voltage divider resistor is connected to the positive electrode of the first DC power supply, and the other end of the second voltage divider resistor is grounded;

[0012] A first MOS transistor, a diode, a second capacitor, a PWM output pin, a DC positive output pin, and a DC negative output pin, wherein the input end of the PWM output pin is connected to the output end of the second comparator, the gate of the first MOS transistor is connected to the output end of the second comparator, one of the source and the drain is grounded, and the other is respectively connected to one end of the second capacitor, the positive electrode of the diode, and the DC negative output pin; the other end of the second capacitor is respectively connected to the negative electrode of the diode, the DC positive output pin, and the positive electrode of the first DC power supply.

[0013] The first voltage divider circuit includes a first resistor and a second resistor, and the first resistor and the second resistor are connected in series.

[0014] The first resistor and the second resistor have equal resistance values.

[0015] The thermistor is a positive temperature coefficient resistor. In the second voltage divider circuit formed by the fourth resistor and the thermistor, the end connected to the positive electrode of the first DC power supply is the fourth resistor.

[0016] A fifth resistor is provided between the second comparator and the first MOS tube.

[0017] The first MOS transistor is an N-channel MOS transistor.

[0018] The first comparator and the second comparator are integrated on the same integrated circuit.

[0019] The output voltage of the first DC power supply is 12V.

[0020] The capacitance of the second capacitor is 1000 microfarads.

[0021] The capacitance of the first capacitor is 100 microfarads.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. By designing the first comparator and the second comparator, combining the second capacitor and the diode, and three output pins, the device is applicable to both DC fans with a PWM speed regulation line and DC fans without a PWM speed regulation line. The voltage stability of the first MOS tube pin can be improved, thereby effectively protecting the first MOS tube. The device has the advantages of durability and wide application range, while taking into account the overall volume.

[0024] 2. The first voltage divider circuit consists of two resistors connected in series, which can provide a more stable voltage.

[0025] 3. The first comparator and the second comparator are integrated on the same integrated circuit, further reducing the size.

[0026] 4. The host computer signal is used as the input of the inverting input terminal, and the two ends of the first capacitor are connected to the output terminal and the inverting input terminal of the first comparator respectively, so that it is applicable to control signals of different frequencies, further broadening the scope of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural diagram of the utility model;

[0028] Figure 2 The output signal of the first comparator when the host computer signal frequency is 25kHz;

[0029] Figure 3 The output signal of the first comparator when the host computer signal frequency is 20kHz;

[0030] Figure 4 The output signal of the first comparator when the host computer signal frequency is 15kHz;

[0031] Among them: R1, the first resistor, R2, the second resistor, R3, the third resistor, R4, the fourth resistor, R5, the fifth resistor, C1, the first capacitor, C2, the second capacitor, U1A, the first comparator, U1B, the second comparator, Q1, the first MOS tube, FAN1, the first DC fan, FAN2, the second DC fan, D1, the diode, NTC1, the thermistor, PWMout, the PWM output pin, FAN+, the DC positive output pin, FAN-, the DC negative output pin, CLKin, the host computer signal. DETAILED DESCRIPTION

[0032] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0033] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition or explanation in subsequent drawings.

[0034] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention. In addition, the terms "proximal", "distal", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. Physical quantities in formulas, unless separately marked, should be understood as basic quantities of the International System of Units, or derived quantities derived from basic quantities through mathematical operations such as multiplication, division, differentiation, or integration.

[0035] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0036] A DC fan automatic temperature control and speed regulation circuit, such as Figure 1 Shown, including:

[0037] A first comparator U1A, a first voltage divider circuit, a third resistor R3, and a first capacitor C1, wherein the inverting input terminal of the first comparator U1A is connected to the host computer through the third resistor R3, the non-inverting input terminal is connected to the voltage divider output terminal of the first voltage divider circuit, one end of the first voltage divider circuit is connected to the positive electrode of the first DC power supply, and the other end is grounded, one end of the first capacitor C1 is connected to the inverting input terminal of the first comparator U1A, and the other end is connected to the output terminal of the first comparator U1A;

[0038] A second comparator U1B, a fourth resistor R4, and a thermistor NTC1 are connected in series to form a second voltage divider circuit, one input end of the second comparator U1B is connected to the output end of the first comparator U1A, and the other input end is connected to the voltage divider output end of the second voltage divider resistor. One end of the second voltage divider resistor is connected to the positive electrode of the first DC power supply, and the other end is grounded;

[0039] A first MOS transistor Q1, a diode D1, a second capacitor C2, a PWM output pin PWMOUT, a DC positive output pin FAN+, and a DC negative output pin FAN- are provided. The input end of the PWM output pin PWMOUT is connected to the output end of the second comparator U1B. The gate of the first MOS transistor Q1 is connected to the output end of the second comparator U1B. One of the source and drain of the first MOS transistor Q1 is grounded, and the other is respectively connected to one end of the second capacitor C2, the positive electrode of the diode D1, and the DC negative output pin FAN-. The other end of the second capacitor C2 is respectively connected to the negative electrode of the diode D1, the DC positive output pin FAN+, and the positive electrode of the first DC power supply.

[0040] By designing the first comparator U1A and the second comparator U1B, in combination with the second capacitor C2 and the diode D1, and three output pins, the device is applicable to both DC fans with a PWM speed regulation line and DC fans without a PWM speed regulation line. The voltage stability of the pin of the first MOS tube Q1 can be improved, thereby effectively protecting the first MOS tube Q1. The device has the advantages of being durable and having a wide range of applications, while also taking into account the overall volume.

[0041] In addition, since the host computer signal CLKin is used as the input of the inverting input terminal in this embodiment, the output terminal and the inverting input terminal of the first comparator U1A are connected to each other through the two ends of the first capacitor C1, thereby being applicable to control signals of different frequencies, further broadening the scope of application. Of course, in other embodiments, this part can also adopt a method similar to that in Chinese patent CN104265670A, that is, replacing the first comparator U1A, the first voltage divider circuit, the third resistor R3 and the first capacitor C1 with a structure that can independently generate a triangular wave, but this will narrow its scope of application to a certain extent.

[0042] The host computer signal CLKin provided by the host computer is specifically a square wave with a duty cycle of 50%, such as Figures 2 to 4 As shown in the image above, the host computer signal CLKin is a square wave of 25kHz, 20kHz and 15kHz, and the corresponding signals output by the first comparator U1A are as follows: Figures 2 to 4 As shown in the image below.

[0043] Generally, in most embodiments, the first voltage divider circuit includes a first resistor R1 and a second resistor R2, and the first resistor R1 and the second resistor R2 are connected in series. The first voltage divider circuit consists of two resistors in series, so that a more stable voltage can be provided. In this embodiment, the resistance values ​​of the first resistor R1 and the second resistor R2 are equal. Specifically, in all embodiments, the voltage ratio of the first resistor R1 and the second resistor R2 determines the voltage level of the voltage divider output end of the first voltage divider circuit, and therefore can be adjusted according to actual conditions.

[0044] In addition, in the present application, the thermistor NTC1 is a positive temperature coefficient resistor. In the second voltage divider circuit formed by the fourth resistor R4 and the thermistor NTC1, one end connected to the positive pole of the first DC power supply is the fourth resistor R4. In this way, on the one hand, the cost is lower, and on the other hand, it has more stable working conditions while having multiple outputs and a wider range of applications.

[0045] In addition, in this embodiment, a fifth resistor R5 is provided between the second comparator U1B and the first MOS transistor Q1 , and the first MOS transistor Q1 is an N-channel MOS transistor.

[0046] In addition, in this embodiment, the first comparator U1A and the second comparator U1B are integrated on the same integrated circuit, further reducing the size. The output voltage of the first DC power supply is 12V, the capacitance of the second capacitor C2 is 1000 microfarads, and the capacitance of the first capacitor C1 is 100 microfarads.

[0047] A square wave with a set frequency and a duty cycle of 50% is provided through the host computer signal CLKin. Based on the energy storage of the first capacitor C1, a triangle wave with the same frequency can be output from the first comparator U1A, which can be applied to fans of different specifications. Since the resistance of the thermistor NTC1 decreases as the temperature increases, for the second voltage divider circuit, the temperature increase will cause the voltage at the voltage divider output end of the second voltage divider resistor to decrease, thereby increasing the duty cycle of the PWM signal output by the second comparator U1B and increasing the second DC fan FAN2 connected to the PWM output pin PWMOUT. The power is increased, thereby improving the heat dissipation effect. Similarly, for the first fan, the conduction time can be adjusted through the first MOS tube Q1. Unlike the MOS tube in the prior art that is in the amplification working area, the function of the first MOS tube Q1 in the present application is chopping. At this time, combined with the second capacitor C2 and the diode D1, the operating voltage of the first MOS tube Q1 can be made more stable, thereby making the overall circuit function more durable and reducing losses, with the advantage of low energy consumption. The input end of the first DC fan FAN1 is respectively connected to the DC positive output pin FAN+ and the DC negative output pin FAN-.

[0048] If the above functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, 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. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

Claims

1. A DC fan automatic temperature control and speed regulation circuit, characterized in that: include: A first comparator, a first voltage divider circuit, a third resistor and a first capacitor, wherein the inverting input terminal of the first comparator is connected to the host computer through the third resistor, the non-inverting input terminal is connected to the voltage divider output terminal of the first voltage divider circuit, one end of the first voltage divider circuit is connected to the positive electrode of the first DC power supply, and the other end is grounded, one end of the first capacitor is connected to the inverting input terminal of the first comparator, and the other end is connected to the output terminal of the first comparator; a second comparator, a fourth resistor, and a thermistor, wherein the fourth resistor and the thermistor are connected in series to form a second voltage divider circuit, one input end of the second comparator is connected to the output end of the first comparator, the other input end of the second comparator is connected to the voltage divider output end of the second voltage divider resistor, one end of the second voltage divider resistor is connected to the positive electrode of the first DC power supply, and the other end of the second voltage divider resistor is grounded; A first MOS transistor, a diode, a second capacitor, a PWM output pin, a DC positive output pin, and a DC negative output pin, wherein the input end of the PWM output pin is connected to the output end of the second comparator, the gate of the first MOS transistor is connected to the output end of the second comparator, one of the source and the drain is grounded, and the other is respectively connected to one end of the second capacitor, the positive electrode of the diode, and the DC negative output pin; the other end of the second capacitor is respectively connected to the negative electrode of the diode, the DC positive output pin, and the positive electrode of the first DC power supply.

2. The DC fan automatic temperature control and speed regulation circuit according to claim 1, characterized in that: The first voltage divider circuit includes a first resistor and a second resistor, and the first resistor and the second resistor are connected in series.

3. The DC fan automatic temperature control and speed regulation circuit according to claim 2, characterized in that: The first resistor and the second resistor have equal resistance values.

4. The DC fan automatic temperature control and speed regulation circuit according to claim 1, characterized in that: The thermistor is a positive temperature coefficient resistor. In the second voltage divider circuit formed by the fourth resistor and the thermistor, the end connected to the positive electrode of the first DC power supply is the fourth resistor.

5. The DC fan automatic temperature control and speed regulation circuit according to claim 1, characterized in that: A fifth resistor is provided between the second comparator and the first MOS tube.

6. The DC fan automatic temperature control and speed regulation circuit according to claim 1, characterized in that: The first MOS transistor is an N-channel MOS transistor.

7. The DC fan automatic temperature control and speed regulation circuit according to claim 1, characterized in that: The first comparator and the second comparator are integrated on the same integrated circuit.

8. The DC fan automatic temperature control and speed regulation circuit according to claim 1, characterized in that: The output voltage of the first DC power supply is 12V.

9. The DC fan automatic temperature control and speed regulation circuit according to claim 1, characterized in that: The capacitance of the second capacitor is 1000 microfarads.

10. The DC fan automatic temperature control and speed regulation circuit according to claim 1, characterized in that: The capacitance of the first capacitor is 100 microfarads.

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