A PWM signal input circuit for low-side drive

Abstract

This utility model relates to the field of PWM signal input technology for brushless electronic fans, and discloses a PWM signal input circuit for low-side drive, including a reference voltage generation unit, a comparison unit, a filtering unit, a current limiting unit, a pull-up resistor R1, and a low-pass filter. In actual use, the PWM signal is filtered by the filtering unit and current limited by the current limiting unit before being input to one input terminal of the comparison unit. The comparison unit compares the signals input to its two input terminals and outputs the signal, which is then filtered by the low-pass filter before being output. This replaces the traditional integrated circuit for inputting the PWM signal to the control unit. The entire circuit has a simple structure, low cost, and uses common components, eliminating procurement cycle limitations.

Description

Technical Field

[0001] This utility model relates to the field of PWM signal input technology for brushless electronic fans, specifically to a PWM signal input circuit for low-side drive. Background Technology

[0002] Brushless electronic fans are widely used in automobiles, data centers, and smart homes due to their advantages such as high efficiency and energy saving, intelligent control, long lifespan and low maintenance costs, low noise and quiet operation, wide environmental adaptability, reliability and electromagnetic compatibility. Among them, brushless electronic fans are driven by high-side drive and low-side drive.

[0003] To achieve precise speed control of a brushless electric fan, a PWM speed control signal needs to be input to the control unit, which then controls the fan's speed based on the PWM signal. For existing low-side drives, the PWM speed control signal needs to be processed by a dedicated integrated circuit before being input to the control unit. For example, a commonly used integrated circuit is the UL2003 driver chip. However, using a dedicated integrated circuit for PWM speed control signal input is costly and subject to long procurement cycles. Utility Model Content

[0004] In view of the shortcomings of the background technology, the present invention provides a PWM signal input circuit for low-side drive. The technical problem to be solved is that when driving a brushless electronic fan, the PWM speed regulation signal is input to the main control unit through a dedicated integrated circuit, which has high cost and is subject to procurement cycle limitations.

[0005] To solve the above technical problems, this utility model provides the following technical solution: a PWM signal input circuit for low-side driving, including a reference voltage generation unit, a comparison unit, a filtering unit, a current limiting unit, a pull-up resistor R1, and a low-pass filter;

[0006] The filtering unit is used to filter the PWM signal. The output of the filtering unit is electrically connected to one end of the pull-up resistor R1 and one input of the comparator unit through the current limiting unit. The other end of the pull-up resistor R1 is used to connect to the power supply VCC.

[0007] The reference voltage generating unit is used to provide a reference voltage to another input terminal of the comparison unit, and the output terminal of the comparison unit is connected to the low-pass filter.

[0008] In one embodiment, the filtering unit includes an inductor L1, one end of which is used to input the PWM signal, and the other end of which is the output terminal of the filtering unit.

[0009] In one embodiment, the current limiting unit includes a current limiting resistor R2, one end of which is electrically connected to the output terminal of the filter unit, and the other end of which is electrically connected to one end of the pull-up resistor R1 and one input terminal of the comparator unit.

[0010] In one embodiment, the comparison unit includes transistors Q1 and Q2. The emitters of transistors Q1 and Q2 are electrically connected to one end of resistor R4, and the other end of resistor R4 is used to connect to the driving voltage V1. The base of transistor Q1 is electrically connected to one end of resistor R3, and the other end of resistor R3 is one input terminal of the comparison unit. The collector of transistor Q1 is grounded through resistor R6. The base of transistor Q2 is electrically connected to one end of resistor R5, and the other end of resistor R5 is another input terminal of the comparison unit. The collector of transistor Q2 is the output terminal of the comparison unit and is grounded through resistor R7.

[0011] In one embodiment, the reference voltage generating unit includes resistors R8 and R9. One end of resistor R8 is used to connect to the driving voltage V1, and the other end of resistor R8 is electrically connected to another input terminal of the comparison unit and one end of resistor R9, while the other end of resistor R9 is grounded.

[0012] In one embodiment, the resistors R8 and R9 have the same resistance value.

[0013] In one embodiment, the output terminal of the comparator is electrically connected to one end of the resistor R10, and the other end of the resistor R10 is electrically connected to the voltage regulator unit and the low-pass filter, respectively.

[0014] In one embodiment, the voltage regulator unit includes a Zener diode Z1, the cathode of which is electrically connected to the other end of the resistor R10, and the anode of which is grounded.

[0015] In one embodiment, the low-pass filter includes a resistor R11 and a capacitor C1, one end of the resistor R11 is electrically connected to one end of the resistor R10, and the other end of the resistor R11 is grounded through the resistor C1.

[0016] In one embodiment, the input terminal of the filter unit is also grounded via a TVS diode, TVS1.

[0017] Compared with the prior art, the advantages of this utility model are as follows: In actual use, the PWM signal is filtered by the filtering unit and the current limiting unit in sequence before being input to one input terminal of the comparison unit. The comparison unit compares the signals input to its two input terminals and outputs them, and outputs them after being filtered by the low-pass filter. This replaces the traditional integrated circuit in inputting the PWM signal to the control unit. The entire circuit structure is simple, the cost is low, and the components are all commonly used components, so there is no procurement cycle limitation. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention in the embodiments. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention, and therefore only show the components relevant to the present invention.

[0020] like Figure 1 As shown, the PWM signal input circuit for low-side driving provided in this embodiment includes a reference voltage generation unit 1, a comparison unit 2, a filtering unit 3, a current limiting unit 4, a pull-up resistor R1, and a low-pass filter.

[0021] The filter unit 3 is used to filter the PWM signal. The output of the filter unit 3 is electrically connected to one end of the pull-up resistor R1 and one input of the comparator unit through the current limiting unit 4. The other end of the pull-up resistor R1 is used to connect to the power supply VCC.

[0022] The reference voltage generation unit 1 is used to provide a reference voltage to the other input terminal of the comparison unit 2, and the output terminal of the comparison unit 2 is connected to a low-pass filter.

[0023] In practical use, the PWM signal is filtered by the filter unit 3 and current limited by the current limiting unit 4 before being input to one input terminal of the comparison unit 2. The comparison unit 2 compares the signals input to its two input terminals and outputs the signal, which is then filtered by a low-pass filter before being output. This replaces the traditional integrated circuit in inputting the PWM signal to the control unit. The entire circuit structure is simple, low in cost, and the components are all commonly used components, so there are no procurement cycle restrictions.

[0024] Specifically, in this embodiment, as Figure 1 As shown, the filter unit 3 includes an inductor L1. One end of the inductor L1 is used to input the PWM signal, and the other end of the inductor L1 is the output terminal of the filter unit 3. In practical use, high-frequency filtering can be performed through the inductor L1. For example, the inductance value of the inductor L1 can be 10uH.

[0025] Specifically, in this embodiment, as Figure 1 As shown, the current limiting unit 4 includes a current limiting resistor R2. One end of the current limiting resistor R2 is electrically connected to the output terminal of the filter unit 3, and the other end of the current limiting resistor R2 is electrically connected to one end of the pull-up resistor R1 and one input terminal of the comparator unit 2.

[0026] In actual use, the value of the current-limiting resistor R2 is set according to the current-limiting requirements, and there is no restriction here.

[0027] Specifically, in this embodiment, as Figure 1 As shown, the comparator unit 2 includes transistors Q1 and Q2. The emitters of transistors Q1 and Q2 are electrically connected to one end of resistor R4, and the other end of resistor R4 is used to connect the driving voltage V1. The base of transistor Q1 is electrically connected to one end of resistor R3, and the other end of resistor R3 is one input terminal of comparator unit 2. The collector of transistor Q1 is grounded through resistor R6. The base of transistor Q2 is electrically connected to one end of resistor R5, and the other end of resistor R5 is the other input terminal of comparator unit 2. The collector of transistor Q2 is the output terminal of comparator unit 2 and is grounded through resistor R7.

[0028] In addition, in this embodiment, both transistors Q1 and Q2 are PNP type transistors.

[0029] Specifically, in this embodiment, as Figure 1 As shown, the reference voltage generation unit 1 includes resistor R8 and resistor R9. One end of resistor R8 is used to connect to the driving voltage V1, and the other end of resistor R8 is electrically connected to another input terminal of the comparison unit and one end of resistor R9, respectively. The other end of resistor R9 is grounded.

[0030] In actual use, the driving voltage V1 is divided by resistors R8 and R9 and then input to the other input terminal of the comparator unit 2.

[0031] In this embodiment, resistors R8 and R9 have the same resistance value, so the voltage input to the other input terminal of comparator unit 2 is 0.5V1. For example, the resistance value of resistor R8 can be 5.1K.

[0032] Specifically, in this embodiment, as Figure 1 As shown, the output terminal of comparator unit 2 is electrically connected to one end of resistor R10, and the other end of resistor R10 is electrically connected to the voltage regulator unit and the low-pass filter. The voltage regulator unit includes a Zener diode Z1, the cathode of which is electrically connected to the other end of resistor R10, and the anode of Zener diode Z1 is grounded. In actual use, the voltage regulator unit can ensure the stability of the output voltage.

[0033] Specifically, in this embodiment, as Figure 1As shown, the low-pass filter includes a resistor R11 and a capacitor C1. One end of resistor R11 is electrically connected to one end of resistor R10, and the other end of resistor R11 is grounded through resistor C1. In practical applications, filtering with a low-pass filter can ensure the stability of the signal input to the control unit and improve circuit stability.

[0034] Specifically, in this embodiment, as Figure 1 As shown, the input terminal of filter unit 3 is also grounded through TVS diode TVS1. In practical use, surge protection can be provided through TVS diode TVS1.

[0035] Based on the above description and inspired by this utility model, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A PWM signal input circuit for low-side driving, characterized by, It includes a reference voltage generation unit, a comparison unit, a filtering unit, a current limiting unit, a pull-up resistor R1, and a low-pass filter; The filtering unit is used to filter the PWM signal. The output of the filtering unit is electrically connected to one end of the pull-up resistor R1 and one input of the comparator unit through the current limiting unit. The other end of the pull-up resistor R1 is used to connect to the power supply VCC. The reference voltage generating unit is used to provide a reference voltage to another input terminal of the comparison unit, and the output terminal of the comparison unit is connected to the low-pass filter.

2. The PWM signal input circuit for low-side driving according to claim 1, wherein The filtering unit includes an inductor L1, one end of which is used to input the PWM signal, and the other end of which is the output terminal of the filtering unit.

3. The PWM signal input circuit for low-side driving according to claim 1, wherein The current limiting unit includes a current limiting resistor R2. One end of the current limiting resistor R2 is electrically connected to the output terminal of the filter unit, and the other end of the current limiting resistor R2 is electrically connected to one end of the pull-up resistor R1 and one input terminal of the comparator unit.

4. The PWM signal input circuit for low-side driving according to claim 1, wherein The comparison unit includes transistors Q1 and Q2. The emitters of transistors Q1 and Q2 are electrically connected to one end of resistor R4, and the other end of resistor R4 is used to connect the driving voltage V1. The base of transistor Q1 is electrically connected to one end of resistor R3, and the other end of resistor R3 is one input terminal of the comparison unit. The collector of transistor Q1 is grounded through resistor R6. The base of transistor Q2 is electrically connected to one end of resistor R5, and the other end of resistor R5 is another input terminal of the comparison unit. The collector of transistor Q2 is the output terminal of the comparison unit and is grounded through resistor R7.

5. The PWM signal input circuit for low-side driving according to claim 4, wherein The reference voltage generating unit includes resistors R8 and R9. One end of resistor R8 is used to connect to the driving voltage V1, and the other end of resistor R8 is electrically connected to another input terminal of the comparison unit and one end of resistor R9. The other end of resistor R9 is grounded.

6. The PWM signal input circuit for low-side driving according to claim 5, wherein The resistors R8 and R9 have the same resistance value.

7. The PWM signal input circuit for low-side driving according to claim 1, characterized in that, The output terminal of the comparator is electrically connected to one end of the resistor R10, and the other end of the resistor R10 is electrically connected to the voltage regulator unit and the low-pass filter, respectively.

8. A PWM signal input circuit for low-side driving according to claim 7, characterized in that, The voltage regulator unit includes a Zener diode Z1, the cathode of which is electrically connected to the other end of the resistor R10, and the anode of which is grounded.

9. A PWM signal input circuit for low-side driving according to claim 8, characterized in that, The low-pass filter includes a resistor R11 and a capacitor C1. One end of the resistor R11 is electrically connected to one end of the resistor R10, and the other end of the resistor R11 is grounded through the resistor C1.

10. A PWM signal input circuit for low-side driving according to claim 1, characterized in that, The input terminal of the filter unit is also grounded through a TVS diode, TVS1.

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